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Natural Materials for Low Cost Plastic DevelopmentNatural Materials for Low Cost Plastic Development
Alan K.T. LauFIMechE FHKIE FIMMM FIoM FIEAust
Professor and Director
Product Testing and Analysis CentreDepartment of Mechanical EngineeringThe Hong Kong Polytechnic UniversityKowloon Hong Kong
Natural Materials and their Composites
•Product Development
•Biomedical Applications
• Type of Natural Fibre
• Mechanical Properties
• Preprocessing Treatment
• Recycled Fibre Composites
• Industrial Applications
Focus
Fibres
Natural fibres Man‐made fibres
Plant‐based fibres(Cellulose or lignocellulose fibres)
Animal‐based fibres(Protein)
Wood Cane, grass & reed
Stalk Leaf Bast(Stem)
Seed Fruit
Hard Wood(Oak)
Soft Wood (Pine)
Bamboo
Phragmites Communis
Elephant grass
Wheat
Maize
Barley
Rye
Oat
Rice
Sisal leaf
Abaca leaf
Henequen
Pineapple leaf
Palm leaf
Flax
Hemp
Jute
Ramie
Kenaf
Cotton
Kapok
Coir
Mineral
Wool &Hair
Lambswool
Goat hair
Angora wool
Cashmere
Yak hair
Horse hair
Flight feather
Down feather
Silk
Tussah silk
Fibrous brucite
Asbestos
Wollastonite
Inorganic whiskers
Human hair
Rice husk
Milkweed seed
Mulberry silk
Spider silk
Bagasse
Esparto
Canary grass
Natural FibersStrength
(Mpa)Elongation at Break
(%)E (GPa)
Kenaf 295-1191 3.5 2.86
Coir 106-175 14.21-49 4-6Bamboo (*) 100 - 600 ---- 3 - 15
Sisal 80-840 2-25 9-38
Palm (*) 248 3.2 25
Banana 529-914 3 27-32
Hemp 310-900 1.6-6 30-70
Pineapple 170-1627 2.4 60-82
Spider silk 875-972 17-18 11-13
Cocoon silk (*) 610-690 4-16 15-17
Wool 120-174 25-35 2.3-3.4
Human Hair(Nikifordis et al 1992)
--- --- 3.43 (elderly)4.46 (Young)
Mechanical Properties
P. Wambua et al. Comp. Sci. Tech. 2003; 63: 125--1264
Vf = 30%, E-glass/PP (Vf=30%) = 32 MPa
Plant-based fibre E-glass Hemp Jute Coir (Coconut)
Sisal Banana Bamboo
Density (g/cm3) 2.55 1.48 1.46 1.25 1.33 1.35 0.89
Tensile Strength (MPa) 2400 550-900 400-800 220 600-700 600 341 - 381
E-Modulus (GPa) 73 70 10-30 6 38 17.85 19.67
Elongation at Failure (%) 3 1.6 1.8 15-25 2-3 3.36 1.73 - 5.2
Moisture Absorption (%) --- 8 12 10 11 10.71 10.14
Hemp
Jute
Coir
Sisial
Banana
Bamboo
Ultimate Tensile Strength of PP = 19 MPa
Pineapple leaf fibre (PALF) in soy-based biothermoplastic.
Liu et al .“Green” composites form soy based plastic and pineapple leaf fiber: fabrication and properties evaluation. Polymer. 2005;46:2710-2721
PALF bundle in 100m(with compatibilizer (PEA-g-GMA)
Bamboo fibre• Low water absorption• Low cost• High strength• Biodegradable• 6-8 months to grow up
Pre-treatment
Polar surface of the natural fibre • Hydrophilic fibre
– Water absorption and diffusion
• Hydrophobic plastic
– Incompatible
– Poor interfacial adhesion1. Expansion of wet fibre (grey region indicating
stress in the matrix
2. Wet composite after stress has been released by molecular relaxation processes
3. Contraction of the fibre during drying
Results
• Decrease the mechanical properties
• Accelerate the degradation
Biopolymer• Starch type
• Cellulose
• Chitin and Chitosan
• Bacterial polymer
Biodegradation Modes• Microorganism
• Fungi
• Bacteria (aerobic activity)
• Enzymes
• Catalytic activities
http://www.devicelink.com/mpb/archive/98/03/002.html
Polymer Melting Point (°C)
Glass-Transition Temp, Tg (°C)
Modulus (GPa)a Degradation Time (months)b
PGA 225—230 35—40 7.0 6 to 12
LPLA 173—178 60—65 2.7 >24
DLPLA Amorphous 55—60 1.9 12 to 16
PCL 58—63 (—65)— (—60) 0.4 >24
PDO N/A (—10)— 0 1.5 6 to 12
PGA-TMC N/A N/A 2.4 6 to 12
85/15 DLPLG Amorphous 50—55 2.0 5 to 6
75/25 DLPLG Amorphous 50—55 2.0 4 to 5
65/35 DLPLG Amorphous 45—50 2.0 3 to 4
50/50 DLPLG Amorphous 45—50 2.0 1 to 2
Polyester 260 175 1.2 to 4.5 Recyclable
Epoxy --- 182 to 206 3.1 Reusebale #
LDPE 98 to 115 -90 to -25 200 – 400 MPa Recyclable
PP 160-180 - 25 to -20 1 to 1.4 Recyclable
a Tensile or flexural modulus.
b Time to complete mass loss. Rate also depends on part geometry.
Silks (from cocoons and spiders) are kinds of animal‐based nature fibres which are high strength, bio‐degradable, commercially‐available and low cost.
Silk Fiber
This outer layer, silk sericin is a natural macromolecular protein derived from cocoon Bombyx mori, and used to ensure the cohesion of the cocoon by gluing silk threads together. The protein resists oxidation, is antibacterial, ultra‐violet (UV) resistant, and absorbs and releases moisture easily.
The cocoon shells subjected to increasing heat treatments. (starting from left to right): untreated; at 190C; 250C; 350C; 450C and 550C for over 0.5 hr.(Zhang et al. J. Appl. Poly. Sci. 2002; 86: 1817‐1820)
Animal‐based Biocomposites
Materials UTS (MPa) Young’s Modulus (GPa) % Strain at break
B. mori silk 610-690 15-17 4-16
Spider dragline silk 2000 30 17-18
Collagen 0.9-7.4 0.0018-0.046 24-68
Collagen X-linked 47-72 0.4-0.8 12-16
PLA 28-50 1.2-3.0 2-6
Tendon (compose mainly of collagen) 150 1.5 12
Bone 160 20 3
Kevlar (49 fibers) 2000 100 2.7
Synthetic Rubber 50 0.001 850
Mechanical properties of silks (silkworm and spider dragline), biomaterial fibers and tissues
Mechanical Property Tests for Silk/PLA Composites
02468
101214161820
Young's Modulus (GPa) Hardness (Hv) Flexural Modulus (GPa)
Pure PLA
PLA (5mm 5% w t.% silk)
Tensile strength and modulus of PBS and five silk/PBS biocomposites(Lee et al. Comp. Sci. Tech. 2005; 65:647‐657)
Chicken FeatherFiber
Samples Modulus of Elasticity (MPa)
Pure PLA 3819
CFF/PLA (fiber from upper (flight) portion of feather)
3492
CFF/PLA (fiber from lower (down) portion of feather)
4184
SamplesFailure Extension
(mm)Flexural Modulus
E (Gpa)
Percentage Increase
(%)
PLA 3.85 3.96 0
HEMP 19.19 4.32 10.3
CFF 2.73 4.06 4.22
Silk 15.67 4.35 11.1
Bamboo 2.67 4.32 10.4
Interfacial Bonding Properties
Basically, the mechanical and thermal properties of natural fibre composites are governed by their interfacial bonding properties. Up to date, many studies have been conducted going along this direction to determine or improve their bonding strength.
• Nanoindentation ‐‐ ??• Microdroplet test• Single fibre pullout test• Microbond test
• Silane treatment (chemical coupling) • Oxidization• Surface cleaned by methanol and benzene• Natural fibre surface layer (enhancement of the bonding strength with PE – coconut (waxy layer))
Manufacturing Processes
• Injection moulding (pellets)
• Compression moulding (mat and fabrics)
• Resin transfer moulding (mat and fabrics)
• Hand lay‐up (chops, mat and fabrics)
• Spray lay‐up (mat and fabrics)
• Infusion and vacuum bagging (mat and fabrics)
Tradition shear‐lag models
• Surface Configuration– Chemical bonding
– Mechanical interlocking
– Polar Hydroxyl (OH) groups
• Hydrophilic – Natural Fibre
• Hydrophobic ‐ Polymer Matrix
• Wettability – Natural Fibre (from filaments to a fibre)
• Degradation at adjacent region of the fibre
• Manufacturing processes
Interfacial Bonding PropertiesDuigou et al. Comp. sci. tech. 2010; 70: 231‐239
Surface of coconut fibre with and without removing waxy layer(Brahmakumar et al. 2005; 65: 563‐569)
Li et al. Comp. Pt A. 2008; 39: 570‐578
• Advantages– Low‐cost and light weight (reduction of the cost of products)
– Non‐abrasive nature (less impact to the environment)
– High specific properties and biodegradability
• Limitations– Moisture absorption
– Poor wettability
– Large scattering in mechanical properties
– Not sufficient understanding of mechanisms controlling their mechanical behaviour and failure modes
– Difficulties in modelling (FEM and theoretical analysis)
– Damage detectability• Acoustic emission
• Embedded sensor technologies
• Thermo‐graphical technologies Sisal fibre (#)
# F.d.A. Silva et al. / Composites Science and Technology 68 (2008) 3438–3443
Industrial Collaboration
• The use of recycled plastics for product development– Design competition with University’s students;
• Design competition
• Factory Visit
• Seminars
• Consultation
– Establishment of “Standard” for quality control of materials;
• Collaboration
– Investigation on the basic properties of natural filler reinforced recyclable plastics
• Research Projects
Recyclable Plastics and their Composites Provide Lightweight andRecyclable Plastics and their Composites Provide Lightweight andEco Solutions for Product, Building, Construction, TransportatiEco Solutions for Product, Building, Construction, Transportation on
and Automobile Engineering Industriesand Automobile Engineering Industries