from for candidature milestone review submissions

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SET Portfolio SAS-001

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School of Applied Science

From for candidature milestone review submissions – Research by thesis

Confirmation of Candidature Review

All Higher Degree by Research candidates are required to make presentations/submissions of their research to a Milestone Review Panel at a School.

This is the formal process whereby the Panel reviews and provides advice on your progress and approves your continuation to the next stage of your research.

Assessment Criteria

Confirmation of candidature milestone assessment criteria – panels are looking for:

a) A clear summary explication of the candidate’s aims and the significance of the research. b) Evidence that the candidate has begun to adequately reflect on their research framework, and its

relationship to the existing body of knowledge. c) Evidence that the candidate understands the proposed methodology and has the skills needed to

undertake the research. d) An indication that the research is original and will produce new knowledge (PhD candidates) or

appropriate to the level of a Masters by research degree. e) A clear and viable schema for completing the degree, including a detailed timeline of the research

program from confirmation to completion.

Candidates must submit a research proposal comprising of approximately 5,000 words for PhD candidates and 2,500 for Master by Research Candidates

SAS-HDR Committee Panel Members - contacts for milestone reviews

Prof Gary Bryant Director of Graduate Research

Dr Lisa Dias Academic Administration Officer (HDR)

Dr James Tardio Chemistry and Environmental Science Disciplines (DR229 and MR229)

A/Prof Andrew Greentree Physics Discipline (DR230 and MR230)

A/Prof Rick Franich Physics Discipline (MR233)

Dr Gregory Nugent Bioscience Discipline (DR231 and MR231)

A/Prof Benu Adhikari Food Science Discipline (DR232 and MR232)

Copies of the documentation should be sent to your senior supervisor, HDR Committee Nominee and [email protected] at least 10 days in advance of the date on which the Review Panel is convened to meet (Date of your oral presentation)

Please also send a copy to Lisa Dias via [email protected] to enable the documents to be forwarded to panel members in time for them to properly consider the material.



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Candidates details

Candidates Name Tai Nyok Ling

Student ID S3517869

School Applied Sciences

Program Code/Name DR232

Senior Supervisor A/Prof. Benu Adhikari

Associate Supervisor Prof. Robert Shanks

Associate Supervisor Dr. Raju Adhikari

A1. Research Proposal for Confirmation of Candidature Reviews

Title of study:

Development and characterization of polysaccharide-polyurethane composite films for food packaging

application

Rationale – Research Abstract

Summarise and articulate what your research is about, what the research aims and research questions are and how the

research is significant.

The most common polymers used today in the packaging application are made from fossil fuel (petroleum). These synthetic polymers display apparent advantages such as good mechanical, barrier and optical properties, heat-sealability, high water resistance and are relatively low in price. However, the petroleum based polymers are non-bio-degradable, come from non-renewable source and exert negative cumulative effect on the environment. The non-biodegradable nature of these polymers and non-renewable nature of their source have been the driving forces behind the drive for developing environmental friendly polymers for food packaging applications [1-3].

Biopolymers such as starch, cellulose, alginates, chitosan and proteins are suitable alternatives for replacing conventional synthetic polymers as they are non-toxic and biodegradable in nature and are derived from renewable sources. Natural polymers can be degraded into basic elements by naturally occurring microorganisms and enzymes [4-6]. However, the above mentioned naturally occurring biopolymers have not gained due attention from industries due to their inherently low mechanical and water vapor barrier properties.

Among the above mentioned polymers starch is the most promising candidate because of its abundance and ease with which it can be converted into packaging films. Conversion of starch into a bioplastic material requires a disruption of the starch granules and their crystalline structure to produce a flowable thermoplastic starch (TPS) [7, 8]. TPS can be easily produced by adding plasticizers (water, glycerol, or polyols), and apply suitable degree of thermal and mechanical (shear) energy. TPS behaves like a synthetic polymer and hence, it is possible to adapt conventional synthetic film processing technique to produce starch films [9].

However, the properties of currently available TPS are far from meeting the target properties, especially the surface hydrophobicity, water vapour barrier and mechanical properties [10-12]. Starch is very sensitive to relative humidity of environment and its high sensitivity to water makes it unsuitable as stand-alone packaging material. Hence, physicochemical properties of starch have to be modified to make it suitable for packaging. The structure of starch have to be altered so that its mechanical and barrier properties become comparable to synthetic polymers. The presence of several hydroxyl groups on starch molecules allows easy alteration of its physicochemical properties through chemical derivatization [13].

TPS was introduced with various chemical or physical interventions such as: blending with another synthetic or natural



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polymer, chemical modification or graft copolymerization with biopolymer, addition of compatibilizers to increase the miscibility of polymers blends [14-19]. Polymers like poly(vinyl alcohol), Poly(hydroxyl alkanoate)s, poly(caprolactone), polyester, polyesteramide, and polyurethane have been reported as the choice of materials to blend with starch. Recently, interest in blending of starch with water dispersible polyurethane (WDPU) has also been increased considerably [20-23] .

Polyurethane (PU) are segmented copolymers consisting of alternating ‘hard’ and ‘soft’ segment blocks. This structure gives rise to two phase morphology in PU. Due to thermodynamic incompatibility between soft segments (SS) and hard segments (HS), polyurethanes exhibit two-phase morphology. Each segment can form its own domain and microdomain. HS domains form ordered structures while the SS domains are generally amorphous. The relative compatibility of the two segments dictates the morphology and resultant properties of polyurethanes. PU has strong mechanical properties; hence, it has been used various applications, such as thermoformable polymers, resins, coatings, adhesives and sealants. Combinations of PU and biopolymer have also been the subject of recent studies. This is because the yield stress of a composite material is higher than its individual components. Synergistic effects between biopolymer and PU have been utilized to create innovative packaging materials, foams, absorbents and textile finishes [21, 24, 25].

The conventional PU is being replaced by waterborne polyurethanes as the former releases toxic volatile organic compounds (VOCs)[14, 26]. Conventional PU itself is insoluble or non-dispersible in aqueous media. Hence, hydrophilic groups, or emulsifiers non-ionic and ionic (anionic, cationic and zwitterionomer) are incorporated into the side chain or back-bone of PU forming polyurethane ionomers (PUI) [27-29]. The molecular weight of ionic PU is usually low, and it contains pendant carboxylate or sulphonate groups, or quaternary ammonium salts. Whereas nonionic PU is an agglomerate of polyol that contains a hydrophilic group such as polyethylene oxide [30, 31]. During dispersion, the ionomer separates into small sphere consisting hydrophobic core and hydrophilic ionic group at the surface and makes the PU water dispersible [32].

WDPU and starch are two incompatible polymers as can be seen from two distinct glass transition temperatures (Tg) of the composite. A large number of research studies have been undertaken to develop procedures to produce compatible starch-PU composites aiming to improve the properties of both PU and starch. These starch-PU composites can be used for producing biodegradable packaging. Despite some success in increasing compatibility between starch

and PU, majority of previous studies were largely focussed in modifying the chemical structure of the polyurethanes. The majority of the studies on PUs have been focussed on developing anionic polyurethane dispersions [20-22, 24]. There are relatively few studies on the cationic PUs [6, 33]. Compounds such as dimethylol propionic acid (DMPA) and N-methyldiethanolamine (MDEA) have been mostly used as emulsifiers for preparation of anionic and cationic polyurethane ionomers. In the above context, the aim of this research is stated as follows.

Research Aim:

This study aims to develop a flexible starch-functionalised polyurethane (starch-FPU) films with improved

hydrophobicity and physical properties.

Research Questions:

1. Can functionalised polyurethane (FPU) improve structural compatibility between starch and polyurethane?

2. How does the functionalization of PU (composition of hard and soft segments) improve the morphology,

hydrophobicity, mechanical and barrier properties of starch-FPU films?

3. Can the nature and concentration of Ionic emulsifier affect the properties of FPU as desired in question 2?

4. How does the isocyanate crosslinkers affect the morphology, hydrophobicity, mechanical and barrier

properties of starch-FPU films?

5. What is the biodegradability of these starch-FPU films?

6. What is the antimicrobial properties of these starch-FPU films?

To address these research questions, the following objectives have been set for this study.



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Objectives:

1. Synthesise series of FPU with different hard and soft segment composition and with various ionic emulsifier

concentration.

2. Synthesise crosslinkers with different molecular weight of polyol.

3. Prepare starch-FPU films from objective 1 and 2 and characterise their structural compatibility, hydrophobicity

/ water barrier and mechanical properties.

4. Determine the biodegradability of starch-FPU films.

5. Determine the antimicrobial properties of starch-FPU films.

Broader research context – situating the research in your discipline

1. Explain how the research program is framed in light of existing work, what existing theories or concepts are

involved and whether it has potential to contribute to an existing or an emergent area.

2. Outline the methodology. If you are a Doctoral candidate discuss how the research is original and likely to

produce new knowledge.

3. Provide a summary of what the final outcome will be.

Abbreviations

The following abbreviations are used in this report.

TPS - thermoplastic starch PU - polyurethane WDPU - water dispersible polyurethane FPU - functionalised polyurethane

PUI - polyurethane ionomers APU - Anionic polyurethane CPU - Cationic polyurethane-starch SS - soft segments HS – hard segments IPNs - Interpenetrating polymer networks PEG iso - PEG isocyanate

HAG-PEG-PU - HAG-PEG isocyanate crosslink films

HA - high amylose HAG - plasticized high amylose starch (HAG) DBTDL - dibutyltin dilaurate HDI - Hexamethylene diisocyanate

PCL - polycaprolactone

PDMS - polydimethyl siloxane

PEG – poly(ethylene glycol) DMPA - dimethylol propionic acid MDEA - N-methyldiethanolamine FTIR - Fourier transform infrared spectroscopy ATR - attenuated total reflectance NMR - Nuclear magnetic resonance spectroscopy GPC - gel permeation chromatography XRD - X-ray diffraction DSC - Differential scanning calorimetry DMTA - Dynamic mechanical analysis TGA - Thermogravimetric analysis SEM - Scanning electron microscopy FESEM - Field emission scanning electron microscopy AFM - Atomic-force microscopy Tg - glass transition temperatures Tm - melting temperature



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Tc - crystallization temperature ΔHm - heat of fusion ΔHc - heat of crystallization

Research approach:

Siloxane is well known for their its high hydrophobicity, low moisture permeability, thermal and oxidative stability,

unique flexibility, low glass transition temperature (Tg), high hydrolytic stability, good biocompatibility and emulsifying

property [34, 35]. The low torsional force constant of the Si-O-Si-O linkage results into exceptionally flexible molecular

structure. The high hydrophobicity of the gem-dimethyl groups and relatively high ionic characteristic of the Si-O

linkage give rise to exceptional surface properties for silicone polymers. The methyl groups of siloxane extend into the

air at the interface generating very low-energy surfaces [36]. Introducing siloxane segment to polyurethane

prepolymer-ionomer chain has proven to be a plausible alternative to improve water resistance of resulting WDPU due

to its hydrophobic structure [37, 38]. To our knowledge, water dispersible siloxane FPU has never been used in starch.

This is the first attempt to incorporate siloxane FPU and develop a hydrophobic starch-FPU composite films.

Most of research to date in developing starch-PU composite materials has used starch as a filler material to provide

reinforcement to composite. Well dispersed starch-PU composite contains up to 20 % w/w starch, above which phase

separation occurs which leads to poor mechanical properties [21, 39]. It is possible to mix WDPU with starch to enhance

the performance the thermoplastic starch. This is because both WDPU and starch contain hydrophilic groups (anionic/

cationic urethane and hydroxyl group). The hydrophilic groups in both starch and PU show potential miscibility which

makes it possible to incorporate WDPU into TPS. Ionic functionalised polyurethanes have reported to have improved

compatible systems, due to coulombic forces between ionic PUI create more entanglements between the polymeric

chains of the ionomers and the blending materials [28, 33]. Incorporating certain optimal concentration of WDPU into

TPS matrix enhances the performance of the said WDPU/TPS composite in terms of mechanical properties (higher

tensile strength and higher elongation at break) and improves hydrophobicity of the resultant starch-PU composite

films. This study will develop starch-FPU films with improved mechanical, water and gas barrier and hydrophobic

characteristics by optimising the NCO/OH molar ratio, selecting better emulsifier and chain extenders.

The effectiveness of blending or chemical cross-linking of two different polymers continue to be a subject of

investigation to obtain a well-mixed new materials. Physical blending or mixing methods attract more attention due to

their operational simplicity compared to Interpenetrating polymer networks (IPNs). It has been reported that

modification of starch-polyurethane through direct blending method show a synergistic effects between those two

material due to the strong hydrogen bonding between the starch and polyurethane [20, 21, 24]. Besides physical

mixing, IPNs have gained much attention due to their enhanced miscibility brought up by interlocking of polymer

chains. IPN structure is obtained when two or more polymer blends are held together by permanent entanglement,

with at least one polymer crosslinked independently in the immediate presence of the other [40, 41]. In this study both

direct mixing and in-situ reaction by forming IPNs will be studied. The extent of formation of IPNs will be investigated by

introduction of unreacted isocyanate (NCO) or NCO terminated prepolymer by covalently attaching with starch. The

IPNs are expected to enhance miscibility between starch and PU by interlocking their polymeric chains. The

introduction of urea linkages is another strategy to improve the intermolecular hydrogen bonding among starch and

urethane linkages which could improve the overall mechanical performance and hydrophobicity of starch films.

Chemical structure, thermal and mechanical properties, and hydrophobicity of the siloxane-rich PU and starch PU

composite films will be studied using Fourier transform infrared spectroscopy (FTIR), 1H and 13C Nuclear magnetic

resonance spectroscopy (NMR), gel permeation chromatography (GPC), X-ray diffraction (XRD), Differential scanning

calorimetry (DSC), Dynamic mechanical analysis (DMTA) and Thermogravimetric analysis (TGA). Surface analysis

techniques such as Scanning electron microscopy (SEM) and Atomic-force microscopy (AFM) will be used to determine

the surface and bulk properties to understand molecular level interaction between starch-FPU and starch.



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Methodology:

The overview of the experimental plan is presented in Figure 1.

Stage 1

Starch + PlasticizerGelatinization optimization

Heating temperature

Heating time

Plasticizer content

Part 1

Plasticized starch (HAG)CSIRO developed

Anionic / Cationic PU+

Film drying and conditioning

Film Characterization

Moisture content

Mechanical test

Contact angle

Part 2

Solution mixing

Stage 4

Selected starch-FPU films

Antimicrobial studyIn-vitro hydrolitic degradation study

Minimum bactericidal concentration (MBC) test

Zone inhibition method

Disk diffusion method Alkali hydrolysis

Enzymatic hydrolysis

Soil burial test

Stage 2

HAGCoupling with

isocyanate crosslinker+



Moisture content

Mechanical test

Contact angle

In-situ reaction

Water vapour permeability (WVP) & Oxygen permeability

Thermal anlaysis (DSC/DMTA/TGA)

Amorphous/ crystalline nature (XRD)

Surface morphology (SEM)

FTIR Microscope

HydrophilicPEG crosslinker

HydrophobicSiloxane crosslinker

Crosslinker Caracterization

FTIR

NMR

GPC

Solution mixing

In-situ reaction

Characterization

HAGSelected formulation

Cationic PU+


Stage 3


Moisture content

Mechanical test

Contact angle

NCO/OH molar ratio

Different Mw siloxane polyol

Mol % emulsifierReaction

Water vapour permeability (WVP) & Oxygen permeability

Thermal anlaysis (DSC/DMTA/TGA)

Amorphous/ crystalline nature (XRD)

Surface morphology (SEM)

FTIR Microscope

FTIR

NMR

GPC

Figure 1. Overview of the experimental design



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1. Materials

All analytical grade chemicals used in synthesises will be commercially sourced wherever possible, for example from

Sigma-Aldrich and other reputable chemical suppliers. Quality of the raw material will be assessed using supplier’s

product specification as well as established analytical methods. All chemical will be used or applied with necessary

purification. All polyol will be dried at 80 or 100˚C under vacuum for at least 12 h before experiment to ensure the total

removal of moisture that may interfere with the isocyanate reactions. Starch powder will be used as received and the

moisture content of the raw materials will be measured and compensated for while preparing the mixed slurry before

gelatinization.

2. Preparation of starch suspension

Stage 1: Part 1

High amylose (HA) corn starch (containing 70-80% amylose) will be used to prepare gelatinized starch. Suspension of

the gelatinized starch will be prepared following Muscat [42] work with slightly modification, as shown in Figure 2

below. HA corn starch and glycerol will be added to distilled water maintaining a total solid concentration of 5% (w/w).

The HA starch: glycerol dry solid ratio will be maintained at 80:20. Gelatinisation of starch-glycerol dispersion will be

carried out using a pressurized microwave reactor, at temperature of 140˚C and pressure of 7 - 8 bars. The suspension

will be held at 140˚C for 15 minutes before cooling down. 140 ˚C for 15 minutes was chosen because the temperature-

time parameters are optimum for complete the starch gelatinization. The progress and the completion of starch

gelatinization will be monitored via a polarized light microscope. A microwave Biotage microwave reactor will be used

to gelatinise starch and starch-polyol mixtures. This is reliable and efficient compared to Parr reactor. This instrument

generates heat using microwave energy which is used for gelatinisation. This process is not constrained by poor thermal

conductivity of the heat exchanging system. However, localized over heating can occur. Mechanical stirrer is used to

distribute the heat and minimise localized overheating. This equipment consists of a cooling unit to cool down the

gelatinized mass or reaction products immediately.

Figure 2. Starch gelatinization process. 3. Starch film casting and conditioning

Film will be cast by syringing 10ml of the suspension into polystyrene petri dishes with 90mm diameter. The film will

then be dried in at air conditioned room for 24 h and then followed by drying in oven at 30˚C for 12 h. Film will be

stored in desiccators containing magnesium nitrate (52.9% RH at room temperature) for at least 48 hours for

conditioning before analysis. Triplicate experiments will be carried out for all variables.

4. Polyurethane (Approach 1) Stage 1: Part 2 4.1 Polyurethane-starch direct mixing Method for preparing water dispersible siloxane functionalized polyurethanes ionomers has been developed at CSIRO. The starch-FPU will be prepared by direct blending of anionic / cationic FPU with starch suspension as shown in Figure 3, below.

Starch powder + plasticizer

• 5 % (w/w) solution.

Gelatinization using microwave reactor

• Gelatinization process is monitored by polarized light microscope.

Optimization of gelatinization condition

• Gelatinisation temperature

• Gelatinisaiton time

Optimization of plasticizer content

• Plasticizer content



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Figure 3. Ionic polyurethane-starch mixing. Stage 3 4.2 Synthesise of starch-FPU The best formulation will be selected from stage 1: part 2 and the best FPU will be synthesised and characterised. This FPU will be mixed with starch by both direct mixing and in-situ during polyurethane synthesis.

4.2.1 Synthesis of FPU and mixing with starch A two-step method, as shown in Figure 4, will be used to synthesise the cationic water dispersible siloxane FPU. Polyurethane prepolymer will be synthesized in a round bottom glass reactor equipped with mechanical stirrer, temperature sensor and its controller, and nitrogen inlet. The reaction will be carried out in nitrogen atmosphere. Firstly, diisocyanate and polyol will be charged into the reactor and the mixture will be heated at 80˚C for 2 h. Secondly, ionic emulsifier and catalyst will be added into the reactor and the reaction will be allowed to proceed at the same temperature until the amount of residual NCO groups reached at a theoretical value, determined by di-n-butylamine back-titration method. The prepolymer will be quaternized and emulsified in deionised water at room temperature. Finally, chain extension process of prepolymer will be carried out immediately at low temperature 5 - 10˚C to avoid reaction between NCO groups and water to yield cationic siloxane FPU [43, 44].

Figure 4. FPU synthesise process and mixing with starch. Mixing of starch and PU The synthesised aqueous cationic siloxane FPU will be slowly added into gelatinized starch at 70˚C and will be stirred for 30min. The reaction mixture will be poured into a Teflon mould and allowed to dry at ambient temperature for 24 h. This mixture will be further dried in an oven at 30˚C for 12 h to prepare film. Films prepared in this way will be conditioned in desiccators containing magnesium nitrate (52.9% RH at room temperature) for at least 48 hours before analysis.

4.2.2 FPU and starch in-situ mixing

For in-situ mixing of starch in polyurethane, as shown in Figure 5, NCO-terminated prepolymers will be prepared as described in 4.2.1. A stock solution of starch will be prepared separately and added to emulsified pre-polymer at temperature 5 - 10˚C to obtain a homogenous solution. Finally, the chain-extension of prepolymer will be carried out using diamines. The starch-FPU dispersion will be poured on a Teflon mould and dried and conditioned according as described in 4.2.1 to prepare the film.

Figure 5. FPU synthesise process and in-situ reaction with starch,

Anionic / cationic FPU

• Develop by CSIRO

Anionic / cationic FPU + Starch

• Mixing with starch

Film casting and drying

• Drying at ambient temperature and oven.

Film conditioning

• Store in desiccator.

• 52.9% RH at room temperature.

starch-FPU film characterization

• Mechanical, moisture content, contact angle

Polyol + Isocynate

• NCO-terminated Polyurethane prepolymer.

Ionic emulsifier + Chain extender

• Incorporate ionic emulsifier and Chain extension step.

Quaternisation

• Formation of cationic groups.

Emulisfication

• Preparing cationic FPU.

Chain extension reaction

• FPU synthesis.

FPU + Starch

mixing

• Preparing starch-FPU by direct mixing.

Polyol + Isocynate

• NCO-terminated Polyurethane prepolymer.

Ionic emulsifier

• Incorporate ionic emulsifier.

Add in Acid

• Formation of cationic groups.

Add in starch subambinet temp

• In-situ reaction.

Chain extension reaction

• FPU synthesis.

starch-FPU suspension

• Casting and drying.



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5. Crosslinker (Approach 2) Stage 2 The hydrophilic / and hydrophobic linker will be prepared by polyaddition reaction [45, 46]. Hydrophilic polyol (polyethylene glycol) or hydrophobic polyol (siloxane polyol) will be used as polyol to react with Hexamethylene diisocyanate (HDI) at NCO/OH=2.0. The linker will be prepared as below as shown in Figure 6.

Figure 6. Crosslinker preparation process. For preparation of PEG linker, HDI will be placed in a two-necked round bottom glass reactor; the solution will be stirred and heated on an oil bath at 70˚C for 10 min. Then, PEG will be added slowly into the reactor. For preparation of Siloxane linker, both Siloxane polyol and HDI will be charged into the reactor and the mixture will be heat at 80˚C for 20 min. Then, 0.2% of dibutyltin dilaurate (DBTDL) catalyst will be added into the reactor and the reaction will be allowed to proceed at the same temperature for 2 h. The completion of the reaction will be monitored by the disappearance of OH peak of polyol at 3000cm

-1, by assuming

that all OH groups of polyol are consumed by NCO groups. The linker obtained in this way will be stored in an air tight container at -5˚C. The starch-linker films will be prepared by mixing the gelatinized starch and linker at room temperature and 80˚C for PEG isocyanate linker and siloxane isocyanate linker respectively. The completion of reaction will be monitored by the disappearance of NCO groups. After mixing the solution will be cast onto a Teflon mould, and will be dried in an air conditioned room for 48 h follow by drying in oven at 30˚C for 24 h. Films will be conditioned in a desiccator containing magnesium nitrate (52.9% RH) for at least 48 h prior analysis. 6. Analytical methods and instruments The measurement/analysis methods to be used in this thesis are listed below.

6.1 Determination of moisture content Moisture content of starch will be determined by drying the starch powder in oven at temperature 105˚C for 12 hours. Dried samples will be stored in desiccators with silica gel until they are equilibrated to24±2

oC before weighing.

6.2 Determination of interaction of HAG and PEG isocyanate crosslinker (PEG iso)

The specific spectral “signatures” of the HAG and PEG iso will be studied by a attenuated total reflectance (ATR) FTIR spectrometer Nicolet 6700 (Thermo Scientific, USA) with a diamond coated zinc selenide crystal plate (reflection plate with pressure arm). The spectra in range of 650-400 cm

-1 with automatic signal gain will be collected in 16 scans at a

resolution of 4 cm-1

and is ratio against a background spectrum.

6.3 Field emission scanning electron microscopy (FESEM)

Microstructure of the test materials and films will be visualized using a field emission scanning electron microsope (FESEM) (FESEM) (Philip XL30). To investigate the cross section, specimens will be immersed in liquid nitrogen for 5 min and randomly fractured. Prior to observation, the specimens will be mounted on the specimen stub and sputtered with a thin layer of Iridium in order to make the sample conductive. Then, the images will be taken at an accelerating voltage of 5kV, spot size 2.0, with magnification of 5000.

6.4 Mechanical properties

The mechanical properties of the films including, tensile strength, Young’s modulus, elongation at break will be measured using an Instron universal tester (Instron 5565, USA). Tests will be carried out at ambient temperature under

Hydrophilic / hydrophobic polyol+ Isocynate

•NCO prepolymer

Intermediate polyol-iso linker

•contains urethane and -NCO reactive groups

Polyol-iso linker + Starch

•Starch-PU



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relative humidity of 50 ± 5 % . The width and grip distance of the specimen will be 5 ± 0.5 mm and 22 ± 0.05 mm respectively and the cross-head speed of 10 mm/min will be used. Tensile specimens will be prepared and tests will be carried out in accordance with ASTM D1708. At least five runs will be made to report the average.

6.5 Differential scanning calorimetry (DSC) The thermal properties of HAG-PEG-PU films will be determined by DSC 3 (Metler Toledo, New Castle, USA), equipped

with a quench cooling accessory. The system will be calibrated using melting temperature (156.6C) and enthalpy of

fusion of (3.28 kJmol-1

) of indium. The samples (about 5 mg) is weighed into aluminium pans and hermetically sealed

and an empty pan is used as the reference. The specimens will be scanned at the heating rate of 10˚C/min over the

temperature range of -50 – 90˚C, to remove the thermal history of the films; the specimen will then be heated two

consecutive runs at the specified temperature range.

6.6 Dynamic mechanical analysis (DMA)

The dynamic mechanical behaviour of the HAG-PEG-PU films will be determined using a dynamic mechanical analyser (PYRIS Diamond DMA, 115V, Perkin-Elmer, Japan) with employing tension mode at oscillation frequency of 1 Hz and a heating rate of 5˚C/min at the temperature range of -100 to 150 ˚C. The sample film (10mm length x 10 mm width) will be set on a twin grip clamp. In order to minimize the moisture loss during measurement, a thin layer of petroleum jelly grease will be applied in the film prior to test. The storage modulus (E’), loss modulus (E’’) and loss angle tangent (tan 𝛿 = E’/E’’) will be determined. The temperature of the peak of the tan 𝛿 curve (Ttan 𝛿) is defined as the glass transition temperatures of the samples [47].

6.7 Contact angle The contact angle will be measured by using a tensiometer (CAM 200, KSV instruments LTD, Finland) using a sessile drop method. Water drops will be deposited on the sample surface and the droplet shape will berecorded. A CCD video camera and image analysis software will be used to measure the contact angle. The enrgy of adhesion or work of adhesion will be determined using the contact angle and the surface tension of water as per...

6.8 NMR Proton nuclear magnetic resonance spectroscopy (1H NMR) will be used to determine the structure and monitor the synthesis process of anionic / cationic polyurethane and crosslinker. The 1H NMR will be performed by using Bruker Av400 NMR (Germany), with deuterated dimethyl sulfoxide (DMSO)-d6 solution as the solvent. Chemical shifts (d) will be given in ppm with tetramethylsilane as a standard.

6.9 X-ray diffraction (XRD) XRD will be used to determine the crystalline/amorphous nature of the materials and films. The crystallinity of starch-PU films will be measured. When analysing a crystalline material, the XRD diffractogram shows the typical crystallinity peaks of each component separately, whereas no peaks are observed for an amorphous material. Wide-angle X-ray diffraction patterns will be recorded on an X-ray diffraction instrument (Siemens D4, Endeavor, Bruker AXS GmbH, Karlsruhe, Germany), using Co-Kα radiation (λ = 0.154 nm) at 40 kV and 30 mA with a scan rate of 4°/min. The diffraction angle will be taken from 4° to 40°.

6.10 Gel permeation chromatography (GPC) The molecular weight and molecular distribution of the polyurethane and crosslinker will be determined using this method.

6.11 Statistical data analysis All statistical analyses will be performed using Minitab statistical version 17. Unless otherwise stated, all experiments will be carried at least in triplicate, and data will be expressed as the mean ± standard deviation (SD) where feasible.

Preliminary results:

Stage 1: Part 1

This section of the report documents some preliminary results achieved during the first year of research.

1. Optimization of starch gelatinization using microwave reactor.

In order to gelatinize high amylose starch, it had to be performed at high temperature (>130˚C) and in constantly



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agitating conditions. In this study, the high amylose starch was gelatinized using Initiator™ - Biotage microwave reactor

is fast and energy efficient compared to conventional Parr reactor. Polarized light microscope was used to ensure

complete gelatinisation of starch. Optimum gelatinisation conditions were determined as shown in Table 1.

Table 1. Experimental condition for starch gelatinization and observations.

Formulations

(Film

sequence)

Reaction

Temp (˚C)

Reaction

Time

(min)

Glycerol

content (%)

Observation

(Light Microscope)

Observations 2

(Sedimentation)

Observation 3

(Solidify) Film Observation

130C-15m-

25G (A) 130 15 25

Starch granules and

starch remnants still

observed No sediment

Forming gel

(retrogradation)

very fast.

Uneven, curvy, crack & hard

130C-30m-

25G (B) 130 30 25

Only starch remnants is

observed Uneven & Curvy

140C-15m-

25G (C) 140 15 25 Fully gelatinized

Slightly pale yellow

sediment. Normal Smooth & flat

140C-30m-

25G (D) 140 30 25 Fully gelatinized

Yellowish sediment

observed Normal Curvy

140C-60m-

25G (E) 140 60 25 Fully gelatinized

Yellowish sediment

severe

Take longer time

to solidify Cracking

150C-60m-

25G (F) 150 30 25 Fully gelatinized

Yellowish sediment

severe

Take much longer

time to solidify Fragmented

Under polarized light, starch granules displayed birefringence, as shown in figure 1 A & B, this property indicates the

radial order centred at the hilum (the growth center of granule), is correlated with the crystallinity of starch molecules.

130C-15m-25G showed that some of the starch granules did not rupture completely and remnant granules (ghost

granules) are still clearly visible (Figure 1C & D). In this temperature, even cooking for 30 min (130-30m-25G), did not

fully gelatinise the starch sample (Figure 1E & F). Cooking time of 15 min at 140˚C seems to be the best cooking time

and cooking temperature to gelatinize high amylose starch because almost no ungelatinised granules were observed

(Figure 1 G & H).



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Figure 7. Light and polarized light microscopic images of starch granules (A), 130C-15m-25G (C), 130C-30m-25G (E),

140C-15m-25G (G); B,D,F & G are the polarized microscopy image of A, C, E & G respectively.

1.1 Effect of heating temperature and time on the properties of films

The quality of the produced films was found to be influence by heating temperature and time and plasticizer content,

as shown in Figure 8.

Heating at low temperature (130˚C) resulted in uneven, wavy and cracking films, which could be due to the presence of

incompletely ruptured granules (film A & B). While heating at 140˚C, for 15- min produced cohesive film (film C). This

observation showed that the absence of incompletely or partially gelatinised granules produces a smooth and even

film. However, longer heating times at this temperature degradation of starch or glycerol or both which produce



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pigmented films or fragile films. As shown in the film D, E & F, it was also observed that the heating time of 30- min or

more resulted into yellowish sediments, as shown in film. Film F, was cooked at 150˚C for 30- min and it produced a

fragmented film.The formation of fragmented film can be attributed to the degradation of starch chains and formation

of small molecular weight compounds.

Figure 8. Images of solution-cast starch films prepared under different experimental conditions: film 130C-15m-25G (A),

130C-30m-25G (B), 140C-15m-25G (C), 140C-30m-25G (D), 140C-60m-25G (E), and 150C-60m-25G (F).

1.2 Effect of plasticizer on film properties

Plasticiser such as glycerol plays an important role in film formation. It slows down the retrogradation of gelatinized

starch at the same time provides flexibility to the produced film.

Starch slurry containing glycerol slowed down the retrogradation of starch compared to the formulation without

glycerol. The formulation without glycerol became a solid gel solid gel right after the mixture was cooling down. It was

also observed that formulation with high amount of glycerol content (30 %) showed considerable amount of yellowish

sediment accumulated at the bottom of the vial and also that the resultant film was much stickier.

It is reported that a good film of glycerol plasticized starch film requires at least 20 % of plasticiser. Starch films

plasticized with 25 % glycerol showed a good plasticizing effect and gave optimum mechanical performance [48-50]. In

contrary, anti-plasticizating behaviour occurs when plasticizer is introduced at low or excess amount, under a critical

level, generally when it is less than 15 %, or greater than 30 % [49, 51-54].

Starch film with 15 % glycerol content yield a cracking (Figure 9 A), due to anti-plasticizing behaviour as reported in

previous studies. The films containing 20 % and 25 % (w/w) (Figure B & C) produced smooth and even films. Film with

30 % glycerol content produced a curled up edges but a very flexible film.



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Figure 9. Images of solution-cast starch films prepared under same experimental conditions with different glycerol

content: 15 % (A), 20 % (B), 25 % (C) and 30 % (D) glycerol content.

In conclusion: the optimum gelatinisation temperature and time for to gelatinisation of starch slurry containing 20-25%

of starch were 140˚C and 15 min, respectively. These two formulations could produce even and smooth film.

2. Effect of conventional hydrothermal gelatinisation and microwave-assisted hydrothermal gelatinisation on

starch films

The mechanical performance of starch films produced by Parr Reactor and microwave were compared. In both

condition, the gelatinisation temperature and time were kept identical (Table 2).

Films prepared by microwave generally produced a softer film with improved elongation compared the films produced

by the conventional hydrothermal treatment using Parr reactor. The latter produced stiffer films (Table 3).

Table 2. Comparison properties of films produced by conventional and microwave-assisted gelatinisation methods.

Starch film Tensile strength

(MPa) Elongation (%) Modulus (MPa) Thickness (mm)

Moisture content

(%)

Starch - xG (Parr reactor) 34.32 ± 9.75 1.41 ± 0.50 1685.57 ± 88.40 0.065 ± 0.001 14.160

Starch - xG (Microwave) 42.69 ± 2.91 7.12 ± 2.26 1614 ± 104 0.077 ± 0.005 13.932

Starch – 20G (Parr reactor) 30.65 ± 2.49 4.60 ± 0.11 1079.67 ± 92.64 0.056 ± 0.005 12.330

Starch - 20G (Microwave) 12.73 ± 0.77 15.82 ± 2.69 561 ± 180 0.070 ± 0.002 10.804

Starch – 30G (Parr reactor) 12.16 ± 1.37 21.81 ± 4.18 323.06 ± 35.11 0.065 ± 0.004 24.080

Starch - 30G (Microwave) 4.39 ± 0.46 27.91 ± 1.01 159 ± 30 0.073 ± 0.002 19.989

3. Effect of plasticizer on the mechanical properties of starch films

The tensile strength and modulus decreased and the elongation increased with the increase of plasticizer up to 30 % of

glycerol (as shown in Table 3). A proper length of drying in oven was necessary to produce better films.

Table 3. Mechanical properties of starch films with different glycerol content.



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Starch film Tensile

strengh (MPa) Elongation (%) Modulus (MPa) Thickness (mm)

Moisture content

(%)

140C-15m-xG 38.45 ± 3.6 6.12 ± 2.52 1425 ± 115 0.076 ± 0.004 9..561

140C-15m-15G 20.24 ± 0.93 9.77 ± 0.09 999 ± 5.22 0.069 ± 0.001 10.848

140C-15m-20G 13.33 ± 0.12 15.19 ± 1.15 447 ± 53 0.070 ± 0.003 12.450

140C-15m-25G 8.34 ± 0.62 21.60 ± 3.08 283 ± 32 0.067 ± 0.004 13.814

140C-15m-20G (Oven dry) 17.11 ± 0.84 19.59 ± 1.54 683 ± 59 0.065 ± 0.001 11.077

140C-15m-25G (Oven dry) 11.21 ± 1.11 30.83 ± 3.80 393 ± 32 0.064 ± 0.002 13.444

140C-15m-30G 4.80 ± 0.44 25.91 ± 1.21 147 ± 24 0.071 ± 0.002 21.504

Stage 1: Part 2

1. Mixing of ioninc PU and starch

1.1 Hydrophobic Anionic polyurethane- starch (APU-starch): 3RA1 (High soft segment: 60% Siloxane content)

As shown in Table 4, APU shows an exceptional elongation property (2899%). It does not break easily and is hydrophobic. Starch possesses good tensile strength and hydrophilic characteristics. The elongation of the APU-starch composite material did not improve when it contained10-20% of APU at the same

time both tensile strength and modulus dropped significantly. Although the APU and starch suspension appeared to mix

well physically, the lack of improvement in elongation means this formulation is not suitable for making APU-starch

films. The contact angle of these formulation increased with the increasing of APU content due to inherent

hydrophobicity of APU.

Table 4. Mechanical properties of hydrophobic APU –starch. The siloxane polyol forms the (high) soft segment of APU.

Starch film Tensile

strength (MPa) Elongation

(%) Modulus

(MPa)

Contact Angle at 10

sec (˚)

Thickness (mm)

Moisture content (%)

Starch (St) 25.19 ± 1.52 9.06 ± 1.54 1160 ± 92.99 39.48 ± 0.25 0.064 ± 0.002 8.857

St-3RA1 (90-10) 18.45 ± 1.71 10.25 ± 1.54 828 ± 36.21 53.57 ± 5.31 0.101 ± 0.002 12.998

St-3RA1 (80-20) 13.80 ± 0.72 11.37 ± 2.20 659 ± 33.69 62.14 ± 2.35 0.105 ± 0.002 13.000

St-3RA1 (60-40) 5.10 ± 0.98 14.50 ± 3.80 420 ± 45.00 75.80 ± 4.20 0.108 ± 0.002 11.850

St-3RA1 (50-50) 4.01 ± 0.65 19.55 ± 4.10 229 ± 53.14 102.61 ± 2.98 0.119 ± 0.030 10.760

3RA1 100% 0.52 ± 0.31 2899.50 ± 1.55 1.11 ± 0.66 97.99 ± 2.59 0.105 ± 0.0 0.677

1.2 Hydrophobic APU-starch: 3RA13 (Low soft segment: 30% Siloxane content)

Based on film physical observation, an increase of hard segment content by decreasing of soft segment content (30%

Siloxane) shows a better miscibility between starch and APU; as compared to high soft segment (60% Siloxane). The

APU-starch film also showed a better contact angle result (as shown in Table 5).The increase of urethane groups

increases the chance of hydrogen bond forming between urethane groups and starch. However, the drawback of high

hard segment content is that it lead to brittle films.



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Table 5. Mechanical properties of hydrophobic APU –starch with low soft segment siloxane polyol.

Sample Name Tensile

strength (Mpa)

Elongation (% ) Modulus (Mpa) Contact Angle

at 10 sec (˚) Thickness

(mm) Moisture

content (%)

Starch (St) 15.47 ± 2.95 17.34 ± 3.84 484.36 ± 152.40 43.72 ± 0.88 0.095 ± 0.003 11.642

St-3RA13 (80-20) 13.35 ± 3.74 3.52 ± 1.47 869.23 ± 70.84 70.27 ± 1.20 0.096 ± 0.003 9.335

St-3RA13 (60-40) 12.83 ± 3.13 3.41 ± 1.39 605.83 ± 31.18 76.48 ± 0.92 0.128 ± 0.009 9.524

St-3RA13 (50-50) 15.59 ± 3.22 3.77 ± 1.16 654.75 ± 100.93 92.37 ± 1.34 0.129 ± 0.004 9.573

St-3RA13 (20-80) 10.61 ± 3.53 6.54 ± 1.30 328.97± 47.61 86.08 ± 0.21 0.144 ± 0.014 7.003

3RA13 100% 20.21 ± 1.34 47.86 ± 9.60 275.49 ± 8.22 92.03 ± 0.32 0.14 ± 0.020 5.959

2 Hydrophilic APU-starch: 3RA90-6

Table 6 shown that hydrophilic APU displayed a better miscibility between starch and APU with improve elongation due

to more hydrophilic groups from APU and better hydrogen interaction among the urethane linkage from and starch.

However, contact angle did not improve show any improvement as APU itself is hydrophilic.

Table 6. Mechanical properties of hydrophilic APU –starch.

Sample Name Tensile

strength (Mpa)

Elongation (% ) Modulus (Mpa) Contact Angle at 10 sec (˚) Thickness (mm)

Moisture content (%)

Starch (St) 19.00 ± 3.01 17.80 ± 1.86 613.42 ± 95.56 40.12 ± 2.85 0.070 ± 0.001 12.011

St-3RA90-6 (80-20) 10.41 ± 0.05 20.84 ± 2.95 382.96 ± 0.03 41.38 ± 4.75 0.061 ± 0.001 9.141

St-3RA90-6 (60-40) 4.37 ± 0.66 48.79 ± 0.17 164.07 ± 4.90 52.25 ± 2.80 0.116 ± 0.004 9.441

St-3RA90-6 (50-50) 3.90 ± 0.34 197.23 ± 18.80 148.56 ± 12.88 43.85 ± 0.56 0.120 ± 0.003 9.923

St-3RA90-6 (20-80) 3.38 ± 0.08 1056.11 ± 11.38 20.15 ± 2.02 50.43 ± 0.43 0.099 ± 0.016 7.590

3RA90-6 100% 6.41 ± 0.97 1254.21 ± 129.50 0.76 ± 0.008 44.47 ± 4.64 0.172 ± 0.004 3.877

3 Cationic polyurethane-starch (CPU-starch): 1RA65

Table 7 shown that Hydrophobic CPU displays a good miscibility with starch, with elongation and contact angle showing

good improvement.

Table 7. Mechanical properties of CPU –starch.

Sample Name Tensile

strength (Mpa) Elongation (% ) Modulus (Mpa) Contact Angle at

10 sec (˚) Thickness (mm)

Starch (St) 15.19 ± 0.29 12.11 ± 5.10 575.71 ± 56.82 43.92 ± 2.90 0.107 ± 0.001

St-1RA65 (80-20) 9.63 ± 4.53 39.43 ± 9.16 363.12 ± 89.66 102.92 ± 3.76 0.110 ± 0.003

St-1RA65 (60-40) 6.18 ± 1.00 67.21 ± 8.21 207.08 ± 29.75 110.86 ± 1.10 0.129 ± 0.003

St-1RA65 (50-50) 2.80 ± 0.53 89.22 ± 6.12 186.42 ± 23.35 110.87 ± 0.89 0.120 ± 0.003

St-1RA65 (20-80) 0.45 ± 0.06 89.18 ± 25.07 15.17 ± 4.99 - 0.1067 ± 0.006

Stage 2

Insitu mixing of crosslinker and starch

1. Hydrophobic crosslinker (Siloxane)

Siloxane isocyanate crosslinker with molecular weight (Mw) of 1000, 3500, 5100 g/mol were prepared; however, it

showed poor compatibility and was immiscible with starch due to its hydrophobic nature.

2. Hydrophilic crosslinker (PEG)

PEG isocyanate (PEG iso) crosslinker was more compatible with starch and it reacted with starch much better than the

siloxane isocyanate. The resultant films showed contact angle of >110° and elongation at break of > 1000 % without

compromising tensile properties. A research paper will be drafted incorporating these findings.



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2.1 SEM Figure 10 illustrates the FESEM images of cross-section of plasticized high amylose starch (HAG) and the synthesized

blend of HAG-PEG isocyanate crosslink films (HAG-PEG-PU). As shown in the Figure 10 (a), the microstructure of HAG

give a coarse and pores surface, demonstrated a weak bonding among the starch chains. The increasing of PEG

isocyanate crosslinker (PEG iso), it helps to fill up the pores and turning it into a cohesive structure.

The cohesive film observed with 10-20% PEG iso content (Figure 10 (e) & (f)), revealed the existence of two phases in

the films which corresponding to one mainly composed of starch-rich phase and the second one mainly composed of

PEG-PU-rich phase. With increase of PEG iso crosslinker loading, the PEG-PU phase is become domain and the images

shown the improved compatibility between starch and PEG-PU with excellent adhesion between starch and PEG iso

crosslinker. This can be ascribed to the covalent bond formation between the NCOs & Hydroxyl groups and the co-

crystallization event that occur between the grafted starch and PEG-PU matrix (as shown in Figure 10 (d-f)). Such good

compatibility of starch and PEG iso crosslinker in the matrix is anticipated to play an important role in the improvement

of the performance of the resulting films.

Figure 10. SEM images of HAG (a), HAG-2PEG-PU (b), HAG-5PEG-PU (c), HAG-10PEG-PU (d), HAG-15PEG-PU (e), and

HAG-20PEG-PU (f).

2.2 Mechanical properties The mechanical behaviour of starch HAG and grafted HAG-PEG-PU films was investigated by tensile test at room temperature, the results are presented in Figure 11. Starch film showed a rigid properties with high tensile strength of 17.86 MPa, a high Young’s modulus of 843.23 MPa and a low elongation at break of 17.08%. This behaviour is considered to be inferior for packaging, as material with high flexibility and increase toughness is necessary for wrapping.

The PEG iso has a profound effect on the tensile properties of HAG films, it is evident that with a small amount of PEG iso linker can greatly improve the tensile properties. As compared to HAG, the elongation at break increase with the PEG iso linker loading level, reaching the highest value of 1090% at 20 wt-% PEG iso linker, approximately 64-fold higher than for the HAG film. However, due to the semicrystalline nature of PEG-PU, HAG-PEG-PU films change its property from rigid behaviour to elastic behaviour and possess a low tensile strength and Young’s modulus.

The values of tensile strength of HAG decrease significantly with an increase of PEG iso linker in the range of 2-5 wt-%, reaching a minimum value at 3.27 MPa for HAG-5PEGiso. It increase again with further increase of PEG iso loading level to 6.69 MPa for HAG-20PEGiso, this result can be explain by the strong interaction between starch and PEG-PU and the

a b

d e f

c a



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co-continuous phase created in large amount of co-crystallization of grafted PEG urethane linkage in the matrix as shown in SEM images, therefore it enhance the tensile strength.

On the other hand, Yong’s modulus dropped from 843 to 3.49 MPa with increasing of linker content, it indicating the elastomeric behaviour of these HAG-PEG-PU films.

Figure 11. Mechanical properties of HAG-PEG-PU films.

2.3 Contact angle

The results of contact angle measurements are presented in Figure 12. The hydrophobicity of starch film increase as

increasing of PEG iso crosslinker increases, with contact angle increase from of 50˚ up to 111˚ at 20% crosslinker

content. The incorporation of PEG iso crosslinker shown great influence on HAG-PEG-PU films, the covalent boding

formed between urethane linkage and starch leading to good interaction among the starch chain. Where the urethane

linkage sealed up the vacant space among the starch molecular chain and restricted the movement of the molecular

chain. Therefore, the vacant space for water passage was then limited and resulting in increased of contact angle as

increasing of crosslinker.

17.86

5.11

3.27 3.89

6.92 6.61

17 25

463

876

1047 1092

843

302

105

22 10 3 0

200

400

600

800

1000

1200

0.00

5.00

10.00

15.00

20.00

25.00

Starch 2% PEG iso 5% PEG iso 10% PEG iso 15% PEG iso 20% PEG iso

Mo

du

lus

(MP

a) &

Elo

nga

tio

n (

%)

Ten

sile

str

engt

h (

MP

a)

Mechanical Properties

Tensile strength (MPa) Elongation (% ) Modulus (MPa)



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Figure 12. Contact angle of HAG-PEG-PU films.

2.4 DSC

To further understand the structure and interaction between the two components, DSC studies of the HAG and HAG-PEG-PU films were conducted. Table 8 shows the DSC thermal properties of HAG, PEG 1000 and HAG-PEG-PU with varying amount of Linker. In all curves, the grafted HAG-PEG-PU films show a well-defined melting endotherm peaks around 19 to 27˚C and a crystallization endotherm around -19 to 0˚C. However, these peaks are not present in HAG film, indicating that the PEG soft segment of PU polymeric chains is likely to form a crystalline structure with starch. As pure PEG 1000 shows a melting and crystallization peaks at 40 ˚C and 25 ˚C respectively, It observed that the melting and crystallization temperature of PEG 1000 is depressed by the presence of isocyanate. By increase the crosslinker content, the melting peak and crystallization peak of HA-PEG-PU films thermograms show changes of broad peak to a sharp peak and shift from 19 to 27˚C and -19 to 0˚C respectively. The heat of fusion (ΔHm) and the corresponding heat of crystallization (ΔHm) of HAG-PEG-PU also increase from 2.7 to 30.5 Jg

-1 and 2.0 to 28.3 Jg

-1 respectively. This shifts of

temperature and increase of heat changes are attributed to the increase of PEG soft segment rich phase in the matrix.

Table 8. Thermal properties of HAG-PEG-PU films. Tm = melting temperature, Tc =crystallization temperature, ΔHm = heat of fusion, ΔHc =heat of crystallization.

Formulation Tm (˚C) ΔHm (Jg-1

) Tc (˚C) ΔHc (Jg-1

)

Starch - - - - PEG 1000 40.01 138.86 25.61 131.79 HAG-2PEGiso 18.79 2.69 -19.31 2.03 HAG-5PEGiso 20.08 11.13 -14.45 9.25 HAG-10PEGiso 23.39 21.38 -0.06 19.05 HAG-15PEGiso 23.33 23.78 -0.05 22.96 HAG-20PEGiso 27.03 30.53 0.3 28.34

0

20

40

60

80

100

120

Starch 2 5 10 15 20

Co

nta

ct a

ngl

e (

˚)

PEG iso linker content (%)

Contact Angle



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Expected Outcomes:

1. Experimentally validated procedures to synthesize a series of starch-FPU based flexible films. In-depth

understanding the effect of polyurethanes composition and mixing approach, and PU effect on the structure

and properties of starch-FPU films.

2. The physicochemical interaction and structure property of FPU and starch will be quantified and the

underlying mechanism will be explained. Understanding the molecular level interaction between FPU and

starch, characterise and evaluate thermal properties, mechanical properties and surface properties of the

starch-FPU films.

3. Understanding the effect of FPU on the antimicrobial and hydrolytic degradation properties of starch-FPU

films.

Initial review of literature and references

Include a concisely selected preliminary list of readings and references of importance to the research

Literature review 1. Starch selection

Starch is commonly available biomaterial from renewable source. It easily undergoes chemical modification and allows formation of functioning packaging films[55]. It is available as semi-crystalline granules in plants, and consists of linear amylose and highly branched amylopectin [56]. The property of starch can have significant impact on the material

properties of starch-based films. Starches with different amylose content have very different thermal, rheological, and processing properties. The amylose content of starch can significantly influence its functional properties including water solubility, swelling and gelatinization [57, 58]. When comparing starch with high and low amylose content; high amylose content contribute to good film forming ability and functional properties of starch films due to its linear long chains which have high a tendency to interact by hydrogen bonds to from a flexible and stiffer films. As for amylopectin, the branch structure of such starch film typically possessed low mechanical properties [51, 59, 60]. In this study, high amylose starch is selected because of its unique functional properties and ability to form a strong film. Because of the good film forming behavior of high amylose starch it is most frequently used for making packaging films.

2. Developing methodology for starch gelatinization.

In order to gelatinize high amylose starch, it has to be performed under high temperature (>130˚C) and constantly

agitating conditions. Various methods have been reported to gelatinize high amylose starch using Parr reactor [51, 62],

autoclave [63, 64], other hydrothermal modules [65], gamma irradiator [66], minijet cooker [61], Infrared heat-

moisture treatment, and plasma treatment [67]. There are only a handful studies citing the use of microwave oven. The

microwave-assisted gelatinization is mostly used in gelatinizing low amylose starch that gelatinise below 100˚C [68, 69].

In this study, high amylose starch will be gelatinized using Initiator™ - Biotage microwave reactor. It comes with

intelligent features such as rapid heating, cooling system, vortex mixing, pressurized system and fully automated

system. Microwave energy has long been used in synthesising monomers as well as polymers. It has been proven to

reduce side reactions, shorten overall reaction time, and produces a better overall polymer yield.



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3. Starch gelatinisation and drying of films

Methods or procedures used to gelatinise the starch and drying of the cast solution affect the physical properties of the

films [70, 71]. The parameters used for gelatinisation and film drying depend on the nature of starch and the plasticizer

used. The temperature and time of heating, extent of shear mixing and drying conditions affect the quality of the films.

Longer gelatinization time and slow drying rates will resulted in a more solid network, higher degree of crystallinity and

lower water vapor permeability. When starch is gelatinized using a fast heating rate and slow drying, the films exhibited

lower elastic characteristics and slightly higher permeability [72]. It was also known that fast water evaporation

produced a less organized and more amorphous matrix with poorer water barrier property [72]. Drying process alone

has demonstrated a different degrees of crystallinity and alter the microstructure network which affected the

mechanical properties of the film [59]. Therefore, the process of preparation of starch film needs to be optimized in

order to obtain films with and desired properties.

4. Polyurethane and starch I have drafted a review paper covering material properties, film forming process and properties of starch-PU films. Overall, PU-starch polymer blend has shown some promising results. The prospect of PU-starch ionomers are different approaches to further improve their properties and will be covered in the review as well. 5. Synthesis of ionomer polyurethane and the properties of corresponding films. Recent studies demonstrated that the ionic group content, the structure of diisocyanate, mol. wt of polyol, the hard/soft segment ratio, neutralizing agents and chain extenders used for preparation of PU determined the properties of PU [73, 74]. Although starch based PU have been studied by several groups, the relationship between its structure and function is not yet adequately understood [21-23]. There are no studies that are devoted to establish structure-function relationships of water dispersible siloxane PU-starch composites and their potential application in packaging application has yet to be explored. In order to rationally design PU-starch composite materials, an in-depth understanding interaction between starch and PU and the chemical composition and topology of PU is necessary. This fundamental understanding of structure-morphology-property relationships enables synthesis of starch-PU composite materials with predictable morphological features and mechanical properties.

5.1 Effect of Hard and soft segments Hard segment (HS) typically consists of disocyanate, chain extender, ioninc groups, and end-capping agents. In contrast to the soft segment (SS), the HS typically has a high glass transition temperature as it is semicrystalline or highly ordered [74]. The restricted movement imposed by HS domains at phase boundaries alter the Tg of the SS [75]. The physical and mechanical properties can be tailored by altering the HS content [76] The Increase in HS content changes the morphological by interconnecting to the isolated hard domain, which lead to high strength and low elongation material [77]. Chattopadhyay et al. (2007) claimed that the presence of three-dimensional hydrogen bonding within HS domains aids to the cohesion or strength of the hard domain. The crystallites and the hydrogen bonded ordered structure between urethane/urethane groups and urethane/ ester groups are responsible for the water resistance properties of the polyurethane material [78]. SS occupies large proportion of WDPU chains and contribute to its properties performance [74]. Polyester SS is hydrolytically labile; however, it possesses excellent mechanical properties [79]. These properties are derived from the ability of the polyol to crystallize or undergo strain-induced crystallization [80]. Thus, polyester SS is a material of choice for biodegradable application. Polyether SS are often used to improve flexibility or hydrophilicity of PU. Polyethers are more hydrolytically stable than polyesters, and they can be used in combination with polyester to tailor the biodegradable properties [81]. Polyether urethanes typically have lower moduli than those of polyester urethanes and are often selected when high flexibility and extensibility are needed [74]. One of the most studied polyesters SS is polycaprolactone (PCL). The hydrophobicity and crystallinity of PCL allow for a slower degradation rate compared to other polyesters. With the exception of very low molecular weight diols, polyester polyols form semicrystalline soft segment that can strongly influence both mechanical properties and degradation rate [74]. When molecular weight of PCL soft segment is increased, the degree of crystallinity increases accordingly. This increase in crystallinity leads to the formation of elastomeric polyurethanes with increased modulus and tensile strength [82, 83]. Zhang et al. (2012) reported that increasing the molecular weight of SS increased the



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hdrophobicity and contact angle of PU-starch films [84]. Similar findings were reported by Rahman (2012), where the water resistance of the PU film was improved by increasing Mw of polydimethyl siloxane (PDMS) SS with fixed mole % of PDMS content [85]. Introducing siloxane segment to polyurethane prepolymer-ionomer chain has proven to be a plausible alternative to improve water resistance of resulting WDPU due to its hydrophobic structure. In the literature PDMS based polyurethane have been reported to have high contact angle and dependent upon the weight percentage siloxane in PU composition [37]. It was also shown that, water resistance of films synthesized from polyol mixtures containing higher percentage of PDMS was significantly better than that observed in films with lower percentage of PDMS soft segment [38].

5.2 Effect of hydrophilic dispersing agent The ability of polyurethane ionomers to readily disperse in water and form stable dispersions is due to the presence of ionic centers in the macrochain. The presence of sufficient amount of hydrophilic agents in WDPU polymer chain means that additional surfactant is not required to produce its stable dispersion in water. However, it is necessary to optimize the amount needed. Dimethylol propionic acid (DMPA) is commonly used as internal emulsifier and a chain extender when reacting isocyanates with anionic WDPU. The ionic form of carboxylic acid group in DMPA provides surface charge to PU particle thus stabilizing the PU in aqueous environment [86]. It was shown that the electrolytic stability of the synthesized dispersion increases when the proportion of pendant COO

- groups in DMPA increases. At the same time, the resistance

of the film to thermal degradation was found to diminish with increase in the percentage of ionic group due to decrease in the percentage of hard segment [32, 87]. Yoon Jang et al. (2002) also showed that increase in the proportion of ionic groups also affected the particle size of dispersion, mechanical properties as well as the Tg of WDPU [43].

References

1. Siracusa, V., et al., Biodegradable polymers for food packaging: a review. Trends in Food Science & Technology, 2008. 19(12): p. 634-643.

2. Cooper, T.A., 4 - Developments in plastic materials and recycling systems for packaging food, beverages and other fast-moving consumer goods, in Trends in Packaging of Food, Beverages and Other Fast-Moving Consumer Goods (FMCG), N. Farmer, Editor. 2013, Woodhead Publishing. p. 58-107.

3. Gourmelon, G. Global Plastic Production Rises, Recycling Lags. New Worldwatch Institute analysis explores trends in global plastic consumption and recycling, 2015.

4. Yoon, B.S., et al., Studies on the degradable polyethylenes: Use of coated photodegradants with biopolymers. Journal of Applied Polymer Science, 1996. 60(10): p. 1677-1685.

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A2. Mandatory Research Course Requirements Have you completed/enrolled in, or have you requested an exemption from, the mandatory research strategy/method course?

1. BIOL1070 has been completed in first semester 2016 2. ONPS2489 is will be enrolled in this semester.



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Outline of progress: summary of the research progress against a detailed research plan/ timeline Provide your research plan/timeline; it should be realistic and viable and demonstrate how you are on a path to complete within the standard duration of candidature.

Consult your supervisor for advice on the appropriate format for the plan/timeline (such as a Gantt chart, Word document etc).

Research Plan

Step

No. Title of Activity Activity Description & Relation to Research Questions

1

Literature review and experiment

design

The available literature on starch, polyurethane and their

composite was thoroughly reviewed. The science and procedure

of developing water dispersible polyurethane were also

thoroughly reviewed. A draft of a review paper has been

prepared and submitted to supervisors.

A concrete experiment design has been planned to conduct the

research. Firstly to successfully synthesize the water dispersible

siloxane polyurethane-starch by direct mixing or in-situ reaction

by forming interpenetrating network between polyurethane and

starch. Secondly, experiment plans are to select the right

diisocyanate structures and molecular weight of polyols, optimize

composition of NCO/OH and ionic emulsifier concentration for

synthesise polyurethane-starch to achieve a bioplastic film well

suited for usage in food packaging industry. In order to achieve

the experimental objective, a series of test will be subjected to

synthesized film to assess the properties and performances. The

test includes: morphology, hydrophobicity, mechanical

properties, barrier properties, antimicrobial properties and finally

in-vitro hydrolytic degradation study.

2

Analytical method/ Instrument

training

Considerable time was spent to familiarise with the working

principle and experimental protocols of relevant

instruments/tests including FTIR, DMA, DSC, SEM, NMR, GPC,

tensile packaging (Instron) and Contact angle measuring

instrument. Hands-on experience was gained through

exploratory experiments listed before.

3

Preliminary trial experiments and

characterization:

Starch gelatinization (Stage 1:

Part 1)

Starch gelatinization was carried out using different methods

such as hot plate heater, Parr reactor and microwave reactor to

select most efficient method. Gelatinised conditions were

optimised in terms of temperature, time and starch to plasticiser

(glycerol) ratio.

4

Preliminary trial experiments and

characterization:

Starch and anionic and cationic

polyurethane blending (Stage 1:

Part 2)

Experiments were carried out to blend anionic and cationic FPU

with starch. The extent of miscibility between starch and siloxane

FPU was been determined through these trials. Experience was

gained in preparing siloxane FPU with different percentage of

hard and soft segments.

5 Preliminary trial experiments and A number of hydrophobic and hydrophilic crosslinkers were



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characterization:

Insitu reaction between starch

and isocyanate crosslinker (Stage

2)

synthesised. The ease or difficulty of reaction between starch and

isocyanate crosslinker was determined through trials.

Crosslinkers with different molecular weight of polyol will be

synthesised in the future. Experience gained to date will help in

future work.

6

Experiment to synthesise cationic

FPU and starch (Stage 3)

Experiments will be carried out to synthesise cationic FPU and

starch-cationic FPU blends/composites by direct mixing and in-

situ reaction methods. The effect of NCO/OH molar ratio,

molecular weight of ionic siloxane polyol, and percentage of ionic

emulsifier on morphology, hydrophobicity, mechanical and

barrier properties of starch film were investigated to gain

experience.

7

Antimicrobial and In-vitro

hydrolytic degradation tests on

starch-FPU composite films

(Stage 4)

Antimicrobial characteristic and hydrolytic degradation (in vitro)

tests will be carried out in selected formulations of starch-FPU

and starch-crosslinker composite films.

8

Progress report / Presentation Progress reports were submitted and presentations were made

to the panel of supervisors in regular basis. Technical issues were

discussed during the meetings with supervisors.

9

Documentation: Publication and

thesis writing

The data, interpretation of the data are being recorded as regular

reports. Time and efforts are now devoted to compile research

papers.



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Research Timeline

Gantt Chart showing shaded time lines. If transferring from Masters to PhD please indicate the time lines already achieved. (Each number box = 3 months)

Activity description

Milestone 1

Confirmation of Candidature

Milestone 2

Mid candidature Review

Milestone 3

Completion Seminar

4th

Year

maximum submission

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

1. Literature Review

2. Preliminary experimentation

3. Preliminary instrument training

4. Preliminary analysis &

performance characterization of

PU-starch films.

5. Experiment Design

6. Experimentation

7. Analysis

8. Progress report / presentation to

supervisors.

9. Documentation: Publication &

thesis writing

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A3. Needs Analysis Form

Please ensure that you and your supervisors have completed the SGR-140 Needs Analysis Form

A4. List any particular issues that you need advice about

Insert text (box will expand)

from for candidature milestone review submissions

Documents