research article preparation and characteristic of pc/pla

Research ArticlePreparation and Characteristic of PCPLATPUBlends by Reactive Extrusion

Yueyun Zhou1 Lifa Luo2 Wenyong Liu3 Guangsheng Zeng3 and Yi Chen3

1 Institute of Architecture and Urban Planning Hunan University of Technology Zhuzhou 412007 China2ZhengYe Packaging Limited Company of Zhongshan Zhongshan China3Key Laboratory of Advanced Materials and Technology for Packaging Hunan University of Technology Zhuzhou 412007 China

Correspondence should be addressed to Yi Chen yiyue514aliyuncom

Received 3 August 2015 Revised 12 October 2015 Accepted 26 October 2015

Academic Editor Hossein Moayedi

Copyright copy 2015 Yueyun Zhou et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

To overcome the poor toughness of PCPLAblends due to the intrinsic properties ofmaterials and poor compatibility thermoplasticurethane (TPU) was added to PCPLA blends as a toughener meantime catalyst di-n-butyltin oxide (DBTO) was also addedfor catalyzing transesterification of components in order to modify the compatibility of blends The mechanical thermal andrheological properties of blends were investigated systematically The results showed that the addition of TPU improves thetoughness of PCPLA blends significantly with the increase of TPU the elongation at break increases considerably and the impactstrength increases firstly and then falls while the tensile strength decreases significantly and the blends exhibit a typical plasticfracture behavior Meantime TPU is conducive to the crystallinity of PLA in blends which is inhibited seriously by PC and damagesthe thermal stability of blends slightly Moreover the increased TPUmakes the apparent viscosity of blendsmelt decrease due to thewellmelt fluidity of TPU themelt is closer to the pseudoplasticitymelt Remarkably the transesterification between the componentsimproves the compatibility of blends significantly andmore uniform structure results in a higher crystallinity and bettermechanicalproperties

1 Introduction

In recent years considerable attention has been paid tobiodegradable polymers mainly owing to increasing inter-est for preservation of environment and substitution forpetrochemical polymers Poly(lactic acid) (PLA) as one ofthe typical biodegradable polymers has been studied andapplied in many fields including tissue engineering [1 2]drug delivery [3] and packing materials [4 5] PLA hasbecome a great alternative to traditional plastics as an envi-ronmentally friendly polymer due to its superior propertiessuch as high strength high stiffness and resistance to fatsand oil However significant brittleness low viscosity lowthermal stability high moisture sensitivity and low solventsresistance are often insufficient for the applications a lot ofregions [6] Many researches have focused on the design andpreparation of new materials with excellent properties typ-ically blending biodegradable polymers with conventional

polymers is considered a convenient and effective methodA lot of blends with PLA such as PLAstarch [7ndash9] PLApoly(vinyl alcohol) (PVA) [10] PLApolycaprolactone (PCL)[11] PLAmontmorillonite [12] PLApoly (butylene adipate-co-terephthalate) (PBAT) [13] and PLArubber [14] haveobtained in-depth research

Recently there is activity in blending PLA bioresinswith engineering polymers to prepare alloy materials forusing in durable products such as laptops cellphones andautoparts which brings the biodegradablity character to thematerials meanwhile keeps the excellent mechanical proper-ties belonged to the engineering polymers Some interestingsystems were exploited for example Zhang et al reporteda PAPLA blend with excellent toughness resulting fromtoughening by polyamide elastomer and the shape memoryeffect was also found [15] Polycarbonate (PC) is a typicalengineering polymer which is commonly used in automotivesheet glazingmedical appliance packing and some electrical

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2015 Article ID 393582 9 pageshttpdxdoiorg1011552015393582

2 Advances in Materials Science and Engineering

O C O C

O

+

O C O C

O

OHC C

O

OHC C O

O

HC C

O

O

(a) Reaction between PC and PLA

O C O C

O

+

+

DBTO

DBTO

(b) Reaction between PC and TPU

C

OHNRC

O

O C

O

C O

OHNRHN

HN

C

O

(TPU)

(TPU)

(TPU)

(TPU)

C O

(PC)n(PC)n

(PC)n(PC)n

(PC)n(PC)n

(PC)n

CH3

CH3

CH3

CH3 CH3

CH3

CH3

CH3

CH3

CH3

CH3

OR998400

(PLA)nn n

(PLA)n(PLA)n

OR998400O

Scheme 1 The reaction equation of transesterification in blends (a) Reaction between PC and PLA (b) Reaction between PC and TPU

applications because of its high tensile strength good electri-cal properties low coefficient of thermal expansion claritydimensional stability and high-heat deflection temperatureHowever the PC resin as a synthetic plastic is hard to berapidly decomposed which is considered as the main reasonto cause the environmental pollution Considering compre-hensively incorporating PLA into PC is an effective methodfor preparing the alloy with excellent mechanical proper-ties and biodegradability Nevertheless PCPLA blends stillexhibit significant brittleness just like the character of thepure PC and PLA resin meantime the deteriorated pro-cessability appearance and mechanical properties are alsothe great drawbacks of blends due to the poor compatibilitybetween PC and PLA [15] Finding a method to improvethe compatibility and the toughness of PCPLA blends is thekey to the application of this kind of blends In previousresearches different kinds of resins were incorporated intoPC resin as flexibilizer for improving its notched impactresistance and rheological properties such as acrylonitrile-butadiene-styrene (ABS) [16] ethylene vinyl acetate (EVA)[17] and thermoplastic urethane elastomers (TPU) [18] thatwere all proved effective Among all of flexibilizers TPU hasattracted wide attention in many fields due to its excellentmechanical properties of high elasticity great flexibilityand toughness and high resistance to tear oxidation andhumidity and it has been usually used instead of old polymersand other elastomers Moreover TPU has also been provedas an effective flexibilizer to improve the toughness of PLA[19] Therefore it is reasonable to believe that TPU wouldbe an available flexibilizer in improving the performance

of PCPLA blends Meantime except for the choice of rawmaterials for guaranteeing the excellent properties of blendswith biopolymers many factors need to be considered andcontrolled and many methods revolved in various aspect ofmaterials preparation were used for example designing aneffective and controllable processing to adjust the molecularstructure and properties of blends [20ndash22] adding nucleantagents or othermaterials in process to induce the crystallinity[23] forming chain extension-branching of biopolymers inprocessing through in situ reaction [24] and introducing thereaction between biopolymers and other functional polymersin processing [25] In the systems with several componentsthe most important factor affecting the properties of blendsis the compatibility of different components in blends Tosolve this problem themolecular structure of all componentsshould be considered carefully If the ester groups exist in allcomponents such as PLA PC and TPU which could happenin the transesterification catalyzed by special catalyst there isno doubt that the transesterification that happened betweenthe components could make the blend tend to be wholethereby resulting in the improved compatibility of blendssignificantly

In this study PCPLATPU blends with various ratio ofraw materials were prepared by melt blending an effectivecatalyst di-n-butyltin oxide (DBTO) was also added to theblends for catalyzing the transesterification between PCTPU and PLA in order to improve the compatibility ofblends and the mechanism was shown in Scheme 1 Theeffect of blends composition and transesterification on thestructure and morphology and thermal rheological and

Advances in Materials Science and Engineering 3

mechanical properties of blendswas investigated comprehen-sively

2 Materials and Methods

21 Materials PLA (PLA711 heat-resistant type) was pur-chased fromHangzhou Ximao Technology Co Ltd (China)the temperature for processing can arrive at 210∘C PC(PC2407 low viscosity and high impact resistant type)was purchased from Bayer Material Technology Co Ltd(German) TPU (85E95W polyester type) was purchasedfrom Bangtai Chemistry Co Ltd (German) di-n-butyltinoxide (DBTO) was purchased from Development of BeijingChemical Technology Co Ltd (China)

22 Sample Preparation The raw materials of PC PLA andTPU were dried and the equipment is dewatered beforeprocessing in order to avoid the PLA degradation duringmelt blending The process of sample preparation is shownas follows PC PLA and TPU were dried in a vacuumoven at 60∘C for 6 hours and then PC PLA TPU andDBTOwith a certain ratio were put into twin-screw extruder(CTE-35 type provided by Ningbo Haitian Stock Co Ltd)which had been fully dehumidified to melt extrusion andthen pelletized the temperature and screw speed of theextruder were set at 210∘Cndash230∘C and 120 rpm and theextrusion process should be under vacuum As has beenproved by viscosity and GPC measure the molecular weightof PLA after extrusion in actual processing temperaturedecreased within 8 After being pelletized the blends wereput into the injection molding machine (HTF90WE typeprovided byNingboHaitian StockCo Ltd) for preparing thesamples

23 Characterization Morphology of blends was observedby scanning electron microscope (SEM) (S-3000N providedby Hitachi Co Ltd) and the samples for observationwere the surface and the cross section slices of impactbroken blends respectively Thermal properties were rep-resented by differential scanning calorimetry instrument(Q20 type provided by TA Instruments in United States)and its analytical method was as follows heat from 20∘Cto 200∘C at the heating rate of 10∘Cmin keep 3min toeliminate thermal history and then cool it down to roomtemperature at the rate of 10∘Cmin and heat it to 200∘Cat the rate of 10∘Cmin for the second time the heatingprocess was in nitrogen atmosphere Thermal stability wasrepresented by thermal gravimetric analyzer (Q50 providedby TA Instruments Company of America) and its analyticalmethod was as follows heat from 25∘C to 700∘C at the rateof 10∘Cmin in nitrogen atmosphere Rheological behaviorwas represented by the capillary rheometer (RH7-D typeprovided by Malvern UK with die 119871119863 = 16) Tensilestrength and elongation at break were tested by the universalmechanical tester (provided by SUNS Company Shenzhen)Notched impact strength was tested by impact tester (CJ-J provided by Zuoji Instruments and Equipment Co LtdShanghai)

4000 3500 3000 2500 2000 1500 1000 500

Wavenumber (cmminus1)

A

B

C

C=O

Figure 1 Spectrums of PCPLATPU blends (A PCPLATPU(703010) B PCPLATPU (703030) C PCPLATPUDBTO(70303008))

3 Result and Discussions

31 Structure and Morphology of Blends For confirming theoccurrence of transesterification FTIR spectra of PCPLAEVA blends and PCPLAEVA blends with catalyst DBTOwere presented in Figure 1 As shown in Figure 1 the absorp-tion peaks of both PCPLATPU and PCPLATPUDBTOblends are similar basically However the peaks around1700 cmminus1 corresponding to the C=O bond in blend exhibitobvious distinguishing The multiple peaks are observed inspectra of PCPLATPU blends with different ratios of rawmaterials and the separated peaks belong to theC=Ogroup ofPC PLA and TPU in blends respectively while in the spec-trum of blend with catalyst DBTO the corresponding peakchanges to be a single peak revealing the homogenizationof these three kinds of C=O groups due to the occurrence oftransesterification between them

For analyzing the compatibility of the blends the surfacemorphology of blends was shown in Figure 2 for comparisonSEM images (a) (b) (c) and (d) are the surface of blendsrespectively From the images it could be seen clearly thatdifferent sizes of split-phases exist obviously in the surfaceof PCPLA blends (image (a)) revealing the obvious poorcompatibility After incorporating TPU the separated phasesstill exist attributed to the unsolved problem related to thecompatibility between three components in blends Howeverthe interface between different phases in blend becomesindistinct and the addition of TPU may play a function incontacting PLA and PC in some degree Comparably the sur-face of blends added catalyst becomes more smooth withoutobvious split-phases indicating that the transesterificationindeed improved the compatibility of blend effectively

32 Thermal Properties of Blends The DSC curves of PLAPCPLA PCPLATPU and PCPLATPUDBTO blendswere shown in Figure 3 As can be seen in Figure 3 theDSC curve of PLA owns obvious crystallization exothermicpeak when the temperature is around 100∘C and a melting


(a) (b)

(c) (d)

Figure 2 SEM images of the surface of blends ((a) PCPLA (7030) (b) PCPLATPU (703020) (c) PCPLATPU (703040) (d)PCPLATPUDBTO (70303006))

0 40 80 120 160 200

Temperature (∘C)

Endo

PCPLATPUDBTO = 70303006

PCPLATPU = 703030

PCPLA = 7030

Pure PLA

Crystallization peak

17234∘C

16812∘C

14985∘C

17463∘C

9471 Jg

3378 Jg

4723 Jg

Figure 3 The DSC curves of PLA PCPLA and PCPLATPUblends

endothermic peak also appears around 170∘C as a symbolof the crystallization of PLA In the DSC curve of PCPLAblend the glass-transition of PC appears at 14983∘C butthere is no obvious melting peak that could be found Theresult indicates that the existence of PC in blends impededthe movement and rearrangement of PLA macromoleculeschain so as to influence its crystallization In curves ofPCPLATPU and PCPLATPUDBTO the melting peaks

that appear at 172∘C and 168∘C prove the existence of thecrystallization of PLA in blends This may be explained bythe idea that the increase of the ldquosoftrdquo chain from TPUdecreased the intramolecular and intermolecular force andenhanced the activity and flexibility of PLA molecular chainwhich all beneficially affected crystallization of PLA Wecan also see that the blend with DBTO shows better abilityof crystallizing due to the improvement of compatibilityFor displaying the effect of adding TPU and catalyst to thethermal properties of blends more directly the crystallinityof blends calculated by normalizing the composition ofblends is shown in Table 1 The melting enthalpy of PLAwith complete crystal is considered 493 Jg From the datashown in Table 1 it could be seen that the crystallization ofPLA almost disappears in PLAPC blends and this may beascribed to the idea that the molecular chain of PC is sorigid that is hard to move which limits the activity andarrangement of PLA chains Meantime with the increase ofTPU the crystallization of PLA appears again and increasesThe molecular chains of elastomer TPU own better activitywhich is conducive to the move of PLA thereby resulting inthe increase of crystallization Moreover it could also be seenthat the addition of DBTO could increase the crystallizationfurther The transesterification integrates the materials inblend and improves the compatibility and homogeneity ofblends all of this is helpful to the crystallization of PLA

Figure 4 showed the thermal weight loss curvesand derivative curves of PCPLA PCPLATPU and


Table 1 DSC data of PLA and PLA composites

Sample 119879119888119888 (∘C) Δ119867119888 (Jg) 119883119888 ()PLA 1564 9471 1921PCPLA = 70 30 mdash mdashPCPLA = 70 40 mdash mdashPCPLATPU = 70 30 10 1571 3152 431PCPLATPU = 70 30 20 1587 3341 498PCPLATPU = 70 30 30 1591 3378 545PCPLATPU = 70 30 40 1598 3381 588PCPLATPUDBTO = 70 30 30 04 1612 4178 571PCPLATPUDBTO = 70 30 30 06 1636 4723 704PCPLATPUDBTO = 70 30 30 08 1645 4892 790PCPLATPUDBTO = 70 30 30 10 1663 4792 833

PCPLATPUDBTOPCPLATPUPCPLA

Temperature (∘C)0 100 200 300 400 500 600 700

0

20

40

60

80

100

Wei

ght (

)

Figure 4 The TGA curves of PCPLA (7030) PCPLATPU(703030) and PCPLATPUDBTO (70303008) blends Thefull line thermogravimetric curve dash line derivative thermo-gravimetry curve

PCPLATPUDBTO blends it is noted that the starttemperature for losing weight of PCPLA is lower than thatof PCPLATPU blends which may be attributed to thereason that TPU chain adsorbed more energy to prohibit thedecomposition of PLA relatively and the derivative curveof PCPLATPU shifts to low temperature compared to thatof PCPLA blend indicating that the TPU is against thethermal stability of blends due to the low decompositiontemperature of TPU Moreover for PCPLATPUDBTOblends the curve is similar to that of PCPLATPU curvewhile the curve becomes more smooth corresponding to themore homogeneous loss weight behavior which also provesthe more homogeneous structure of blends

33 Mechanical Properties of Blends The main purpose ofadding elastomer TPU to PCPLA blends was to improve thetoughness of blends Figure 5 showed the tensile and impact

properties of PCPLA PCPLATPU and PCPLATPUDBTO blends It can be seen clearly from Figure 5 (A BC and D series) that the mechanical properties of PCPLAblends including tensile strength elongation at break andimpact strength all exhibit a significant deterioration trendwith the increase of PLA content the mechanical data ofproperties belonging to PCPLA (7040) blends is only halfof that of pure PC plastic (the impact strength and tensilestrength of PC2407 are 75KJm2 and 66MPa) and the resultscan be attributed to the low strength of PLA as well as theincompatible phase separation due to the poor compatibilitybetween PLA and PC After adding TPU the elongation atbreak of blends increases significantly with the increase ofTPU content while the tensile strength decreases obviouslyrevealing that the soft TPU chain is not conducive to thestrength but still plays a connection role for PC and PLAthereby resulting in the improvement of toughness due tothe more effective dispersion of energy Moreover the impactstrength exhibits a first rise and then fall trend when thecontent of TPU exceeds 25 copies the impact strengthof blend decreases rapidly Although the TPU owns goodflexibility and could modify the compatibility of blends itsintrinsic strength is not high and high content should causethe occurrence of split phase More importantly comparingE curves with D curves in the figure it could be found thatthe addition of catalyst improves the mechanical propertiessignificantly the tensile and impact strength and elongationat break increases considerably due to the improvement of thecompatibility of blends Meantime the properties still showdirect dependency on the content of TPU and the rule isconsistent with that of PCPLATPU blends without DBTO

In order to illuminate the mechanism of property changeof blend the morphology of cross section of blends afterimpact fracture was observed In Figure 6 the SEM imagesof cross section show different breakmorphologies revealingthe different break behavior Apparently the cross section ofPCPLA blends is multilayer with smooth surface withoutplastic deformation which is the characteristic belongingto brittle fracture After incorporating TPU into blendsthe fracture-surface displays complex surface morphologyinstead of obvious multilayer structure and clear substratedeformation and many plastic deformations appear Thisphenomenon may be reasonably explained by the idea thatthe rubber phases were pulled out from the substrate andabsorbed a lot of energy when suffering the impact Thefracture-surface of blend with catalyst exhibits more complexand rough morphology there are lot of slippages corru-gations and deformations appears in the edge of fracturesection

34 Rheological Properties of Blends Rheological proper-ties of the blends play a guiding role and make a greateffect on processing which should be paid the attention inpreparation of blends The influence of TPU and catalyston the rheological properties of PCPLATPU blends wasstudied Figure 7 shows the shear rate-apparent viscositycurves and shear rate-shear stress curves of PCPLATPUblends respectively As shown in Figure 7(a) the addition of


0 10 20 30 40

TPU content

0

4

8

12

16

20

Elon

gatio

n at

bre

ak (

)

ABC

DE

(a)

0 10 20 30 40

TPU content

18

24

30

36

42

48

Tens

ile st

reng

th (M

Pa)

ABC

DE

(b)

ABC

DE

0 10 20 30 40

TPU content

Impa

ct st

reng

th (k

Jm2)

56

48

40

32

24

(c)

Figure 5Mechanical properties of PCPLATPUblends (A PCPLA= 5050 B PCPLA= 6040 C PCPLA= 6535 D PCPLA= 7030 EPCPLADBTO = 703008 TPU content is the ratio of copies eg in image (a) TPU content = 30 corresponds to PCPLATPU = 505030(mass ratio))

TPU increases the viscosity of blends which may be ascribedto the higher viscosity of TPU than that of PLA under theprocessing temperature However the range of increase isstill limited At the same time the addition of catalyst hasno obvious influence on the apparent viscosity of blendsCorrespondingly the shear stress of blends increases withincreasing TPU contentThe non-Newtonian index of blendsfitted by shear rate-shear stress curves of blends (Figure 7(b))was shown in Table 2 and the non-Newtonian index 119899 ofblends comes down with the increase of TPU indicatingthat the characteristic of pseudoplasticity of melts becomesmore obvious These phenomena state that the addition of

TPU makes the blends more sensitive to high shear speedTherefore increasing the rotate speed of screw is helpful tothe processing

4 Conclusion

For developing new materials with high performance andbiodegradability blending engineering plastics PC withbiodegradable PLA is an effectivemethodThough the blendsshow a higher strength the significant brittleness is still anobvious defect attributed to the inherent character of bothPC and PLA resin and the poor compatibility between them


(a) (b)

(c)

Figure 6 SEM images of the impact break section of blends (a) PCPLA (7030) (b) PCPLATPU (703030) (c) PCPLATPUDBTO(70303008)

ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102

Shear rate (sminus1)

(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)

Figure 7 The shear rates-shear viscosity and shear rates-shear stress curves of blends (A PCPLA = 7030 B PCPLATPU = 703010 CPCPLATPU = 703020 D PCPLATPU = 703030 E PCPLATPUDBTO = 70303008)

in blends For solving this problem TPU as a tougheningmodifier was incorporated into the PCPLA blends by meltcoextrusion In order to improve the compatibility of blendsfurther catalyst DBTO was also added to blends to catalyze

the transesterification of the components in blends Throughinvestigating the mechanical thermal and rheological prop-erties of blends systematically the several main results wereobtained


Table 2 The non-Newtonian index of blends in Figure 7

Blends119899 index A B C D ESamples in Figure 7 06768 06492 06167 05674 05562

Firstly the addition of TPU improves the toughness ofPCPLA blends significantly with the increase of TPU theelongation at break increases considerably and the impactstrength increases firstly and then falls while the tensilestrength decreases significantly From the observation bySEM the break section of PCPLATPU blends exhibitstypical plastic fracture characteristic Obviously the additionof soft TPU chains provides the blends with more flexibilitywhile greater flexibility caused by high content of TPUdamages the strength of blends drastically

Secondly with the increase of TPU the crystallinity ofPLA in blends increases gradually and the soft TPU chainsdecrease the intramolecular and intermolecular force andenhance the activity and flexibility of PLA molecular chainswhich is conducive to the arrangement of molecular chainsthereby resulting in a higher crystallinity Nevertheless thethermal stability of blends deteriorates slightly

Thirdly the apparent viscosity of blends melt decreaseswith the increase of TPU due to the well melt fluidity of TPUand the melt is closer to the pseudoplasticity melt which ismore sensitive to high shear speed

Finally DBTO could catalyze the transesterification ofthe components in blends effectively and the structure ofPCPLATPU blends becomes more homogeneous after thereaction revealing the better compatibility When addingDBTO the mechanical properties including tensile impactstrength and elongation at break of blends all increaseand the crystallinity of PLA and thermal stability of blendsimproves In conclusion the transesterification catalyzed byDBTO is conducive to the properties of blends Consideringthe properties of blends comprehensively the optimal ratio ofPCPLATPUDBTO is 70 30 30 08

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors acknowledge the financial support of NationalScience-Technology Support Plan Projects (2014BAD02B062013BAJ10B14) Hunan Province Natural Science Foun-dation (2015JJ4021 13JJ1024) Production-Study-ResearchCooperation Project of Zhongshan (2013C2FC0022) Sci-ence and Technology Planning Project of Guangdong(2013B090600120) and Outstanding Youth Fund of HunanProvince Department of Education (15B064)

References

[1] H Zhou A H Touny and S B Bhaduri ldquoFabrication of novelPLACDHA bionanocomposite fibers for tissue engineering

applications via electrospinningrdquo Journal of Materials ScienceMaterials in Medicine vol 22 no 5 pp 1183ndash1193 2011

[2] S Sheng F Wang Q Ma and X Hu ldquoImpact of foaming airon melting and crystallization behaviors of microporous PLAscaffoldsrdquo Journal of Thermal Analysis and Calorimetry pp 1ndash12 2015

[3] J-Y Park and I-H Lee ldquoControlled release of ketoprofen fromelectrospun porous polylactic acid (PLA) nanofibersrdquo Journal ofPolymer Research vol 18 no 6 pp 1287ndash1291 2011

[4] G Colomines S Domenek V Ducruet and A GuinaultldquoInfluences of the crystallisation rate on thermal and barrierproperties of polylactide acid (PLA) food packaging filmsrdquoInternational Journal of Material Forming vol 1 supplement 1pp 607ndash610 2008

[5] D Gonzalez A R Campos C A M Cunha V Santosand J C Parajo ldquoManufacture of fibrous reinforcements forbiodegradable biocomposites fromCitysus scopariusrdquo Journal ofChemical Technology and Biotechnology vol 86 no 4 pp 575ndash583 2011

[6] H Li and M A Huneault ldquoEffect of nucleation and plasticiza-tion on the crystallization of poly(lactic acid)rdquo Polymer vol 48no 23 pp 6855ndash6866 2007

[7] H Wang X Z Sun and P Seib ldquoMechanical propertiesof poly(lactic acid) and wheat starch blends withmethylenediphenyl diisocyanaterdquo Journal of Applied PolymerScience vol 84 no 6 pp 1257ndash1262 2002

[8] N Wang J G Yu P R Chang and X Ma ldquoInfluenceof formamide and water on the properties of thermoplasticstarchpoly(lactic acid) blendsrdquo Carbohydrate Polymers vol 71no 1 pp 109ndash118 2008

[9] C-S Wu ldquoImproving polylactidestarch biocomposites bygrafting polylactide with acrylic acidmdashcharacterization andbiodegradability assessmentrdquoMacromolecular Bioscience vol 5no 4 pp 352ndash361 2005

[10] T K Ke and X S Sun ldquoStarch Poly(lactic acid) and Poly(vinylalcohol) Blendsrdquo Journal of Polymers and the Environment vol11 no 1 pp 7ndash14 2003

[11] T Takayama and M Todo ldquoImprovement of impact fractureproperties of PLAPCL polymer blend due to LTI additionrdquoJournal ofMaterials Science vol 41 no 15 pp 4989ndash4992 2006

[12] W S Chow and S K Lok ldquoThermal properties of poly(lacticacid)organo-montmorillonite nanocompositesrdquo Journal ofThermal Analysis and Calorimetry vol 95 no 2 pp 627ndash6322009

[13] N W Zhang Q F Wang J Ren and L Wang ldquoPreparationand properties of biodegradable poly(lactic acid)poly(butyleneadipate-co-terephthalate) blend with glycidyl methacrylate asreactive processing agentrdquo Journal of Materials Science vol 44no 1 pp 250ndash256 2009

[14] B Suksut and C Deeprasertkul ldquoEffect of nucleating agentson physical properties of poly(lactic acid) and its blend withnatural rubberrdquo Journal of Polymers and the Environment vol19 no 1 pp 288ndash296 2011

[15] W Zhang L Chen and Y Zhang ldquoSurprising shape-memoryeffect of polylactide resulted from toughening by polyamideelastomerrdquo Polymer vol 50 no 5 pp 1311ndash1315 2009

[16] T Seelig and E Van der Giessen ldquoEffects of microstructureon crack tip fields and fracture toughness in PCABS polymerblendsrdquo International Journal of Fracture vol 145 no 3 pp 205ndash222 2007


[17] Y Zhao Y-X Liao B Yin and M-B Yang ldquoStudy on thereaction of PC andEVAduring processingrdquoPolymericMaterialsScience and Engineering vol 21 no 6 pp 201ndash208 2005

[18] Q Sun C R Zheng S Wu S Cheng and X C Dai ldquoThestudy of PC modified by TPUrdquo Polymer Materials Science ampEngineering vol 15 pp 140ndash144 1999

[19] R-L Yu L-S Zhang Y-H Feng R-Y Zhang and J ZhuldquoImprovement in toughness of polylactide by melt blendingwith bio-based poly(ester)urethanerdquoChinese Journal of PolymerScience vol 32 no 8 pp 1099ndash1110 2014

[20] R Al-Itry K Lamnawar A Maazouz N Billon and CCombeaud ldquoEffect of the simultaneous biaxial stretching on thestructural and mechanical properties of PLA PBAT and theirblends at rubbery staterdquo European Polymer Journal vol 68 pp288ndash301 2015

[21] R Al-Itry K Lamnawar and A Maazouz ldquoBiopolymer blendsbased on poly (lactic acid) shear and elongation rheol-ogystructureblowing process relationshipsrdquo Polymers vol 7no 5 pp 939ndash962 2015

[22] B Mallet K Lamnawar and A Maazouz ldquoImprovement ofblown film extrusion of poly (lactic acid) structure-processing-properties relationshipsrdquo Polymer Engineering amp Science vol54 pp 840ndash857 2014

[23] R Al-Itry K Lamnawar and A Maazouz ldquoRheologicalmorphological and interfacial properties of compatibilizedPLAPBAT blendsrdquo Rheologica Acta vol 53 no 7 pp 501ndash5172014

[24] R Al-Itry K Lamnawar and A Maazouz ldquoReactive extru-sion of PLA PBAT with a multi-functional epoxide physico-chemical and rheological propertiesrdquo European Polymer Jour-nal vol 58 pp 90ndash102 2014

[25] R Al-Itry K Lamnawar and A Maazouz ldquoImprovementof thermal stability rheological and mechanical propertiesof PLA PBAT and their blends by reactive extrusion withfunctionalized epoxyrdquo Polymer Degradation and Stability vol97 no 10 pp 1898ndash1914 2012

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O C O C

O

+

O C O C

O

OHC C

O

OHC C O

O

HC C

O

O

(a) Reaction between PC and PLA

O C O C

O

+

+

DBTO

DBTO

(b) Reaction between PC and TPU

C

OHNRC

O

O C

O

C O

OHNRHN

HN

C

O

(TPU)

(TPU)

(TPU)

(TPU)

C O

(PC)n(PC)n

(PC)n(PC)n

(PC)n(PC)n

(PC)n

CH3

CH3

CH3

CH3 CH3

CH3

CH3

CH3

CH3

CH3

CH3

OR998400

(PLA)nn n

(PLA)n(PLA)n

OR998400O

Scheme 1 The reaction equation of transesterification in blends (a) Reaction between PC and PLA (b) Reaction between PC and TPU

applications because of its high tensile strength good electri-cal properties low coefficient of thermal expansion claritydimensional stability and high-heat deflection temperatureHowever the PC resin as a synthetic plastic is hard to berapidly decomposed which is considered as the main reasonto cause the environmental pollution Considering compre-hensively incorporating PLA into PC is an effective methodfor preparing the alloy with excellent mechanical proper-ties and biodegradability Nevertheless PCPLA blends stillexhibit significant brittleness just like the character of thepure PC and PLA resin meantime the deteriorated pro-cessability appearance and mechanical properties are alsothe great drawbacks of blends due to the poor compatibilitybetween PC and PLA [15] Finding a method to improvethe compatibility and the toughness of PCPLA blends is thekey to the application of this kind of blends In previousresearches different kinds of resins were incorporated intoPC resin as flexibilizer for improving its notched impactresistance and rheological properties such as acrylonitrile-butadiene-styrene (ABS) [16] ethylene vinyl acetate (EVA)[17] and thermoplastic urethane elastomers (TPU) [18] thatwere all proved effective Among all of flexibilizers TPU hasattracted wide attention in many fields due to its excellentmechanical properties of high elasticity great flexibilityand toughness and high resistance to tear oxidation andhumidity and it has been usually used instead of old polymersand other elastomers Moreover TPU has also been provedas an effective flexibilizer to improve the toughness of PLA[19] Therefore it is reasonable to believe that TPU wouldbe an available flexibilizer in improving the performance

of PCPLA blends Meantime except for the choice of rawmaterials for guaranteeing the excellent properties of blendswith biopolymers many factors need to be considered andcontrolled and many methods revolved in various aspect ofmaterials preparation were used for example designing aneffective and controllable processing to adjust the molecularstructure and properties of blends [20ndash22] adding nucleantagents or othermaterials in process to induce the crystallinity[23] forming chain extension-branching of biopolymers inprocessing through in situ reaction [24] and introducing thereaction between biopolymers and other functional polymersin processing [25] In the systems with several componentsthe most important factor affecting the properties of blendsis the compatibility of different components in blends Tosolve this problem themolecular structure of all componentsshould be considered carefully If the ester groups exist in allcomponents such as PLA PC and TPU which could happenin the transesterification catalyzed by special catalyst there isno doubt that the transesterification that happened betweenthe components could make the blend tend to be wholethereby resulting in the improved compatibility of blendssignificantly

In this study PCPLATPU blends with various ratio ofraw materials were prepared by melt blending an effectivecatalyst di-n-butyltin oxide (DBTO) was also added to theblends for catalyzing the transesterification between PCTPU and PLA in order to improve the compatibility ofblends and the mechanism was shown in Scheme 1 Theeffect of blends composition and transesterification on thestructure and morphology and thermal rheological and







4000 3500 3000 2500 2000 1500 1000 500


A

B

C

C=O







(a) (b)

(c) (d)


0 40 80 120 160 200

Temperature (∘C)

Endo


PCPLATPU = 703030

PCPLA = 7030

Pure PLA


17234∘C

16812∘C

14985∘C

17463∘C

9471 Jg

3378 Jg

4723 Jg









Temperature (∘C)0 100 200 300 400 500 600 700

0

20

40

60

80

100

Wei

ght (

)








0 10 20 30 40

TPU content

0

4

8

12

16

20

Elon

gatio

n at

bre

ak (

)

ABC

DE

(a)

0 10 20 30 40

TPU content

18

24

30

36

42

48

Tens

ile st

reng

th (M

Pa)

ABC

DE

(b)

ABC

DE

0 10 20 30 40

TPU content

Impa

ct st

reng

th (k

Jm2)

56

48

40

32

24

(c)




4 Conclusion



(a) (b)

(c)


ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102


(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)













Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials









4000 3500 3000 2500 2000 1500 1000 500


A

B

C

C=O







(a) (b)

(c) (d)


0 40 80 120 160 200

Temperature (∘C)

Endo


PCPLATPU = 703030

PCPLA = 7030

Pure PLA


17234∘C

16812∘C

14985∘C

17463∘C

9471 Jg

3378 Jg

4723 Jg









Temperature (∘C)0 100 200 300 400 500 600 700

0

20

40

60

80

100

Wei

ght (

)








0 10 20 30 40

TPU content

0

4

8

12

16

20

Elon

gatio

n at

bre

ak (

)

ABC

DE

(a)

0 10 20 30 40

TPU content

18

24

30

36

42

48

Tens

ile st

reng

th (M

Pa)

ABC

DE

(b)

ABC

DE

0 10 20 30 40

TPU content

Impa

ct st

reng

th (k

Jm2)

56

48

40

32

24

(c)




4 Conclusion



(a) (b)

(c)


ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102


(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)













Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)


0 40 80 120 160 200

Temperature (∘C)

Endo


PCPLATPU = 703030

PCPLA = 7030

Pure PLA


17234∘C

16812∘C

14985∘C

17463∘C

9471 Jg

3378 Jg

4723 Jg









Temperature (∘C)0 100 200 300 400 500 600 700

0

20

40

60

80

100

Wei

ght (

)








0 10 20 30 40

TPU content

0

4

8

12

16

20

Elon

gatio

n at

bre

ak (

)

ABC

DE

(a)

0 10 20 30 40

TPU content

18

24

30

36

42

48

Tens

ile st

reng

th (M

Pa)

ABC

DE

(b)

ABC

DE

0 10 20 30 40

TPU content

Impa

ct st

reng

th (k

Jm2)

56

48

40

32

24

(c)




4 Conclusion



(a) (b)

(c)


ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102


(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)













Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







Temperature (∘C)0 100 200 300 400 500 600 700

0

20

40

60

80

100

Wei

ght (

)








0 10 20 30 40

TPU content

0

4

8

12

16

20

Elon

gatio

n at

bre

ak (

)

ABC

DE

(a)

0 10 20 30 40

TPU content

18

24

30

36

42

48

Tens

ile st

reng

th (M

Pa)

ABC

DE

(b)

ABC

DE

0 10 20 30 40

TPU content

Impa

ct st

reng

th (k

Jm2)

56

48

40

32

24

(c)




4 Conclusion



(a) (b)

(c)


ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102


(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)













Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 10 20 30 40

TPU content

0

4

8

12

16

20

Elon

gatio

n at

bre

ak (

)

ABC

DE

(a)

0 10 20 30 40

TPU content

18

24

30

36

42

48

Tens

ile st

reng

th (M

Pa)

ABC

DE

(b)

ABC

DE

0 10 20 30 40

TPU content

Impa

ct st

reng

th (k

Jm2)

56

48

40

32

24

(c)




4 Conclusion



(a) (b)

(c)


ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102


(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)













Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c)


ABC

DE

Shea

r visc

osity

(Pamiddot

s)

103

102

103

102


(a)

Shea

r stre

ss (k

Pa) 10

2

101

100

ABC

DE

103

102


(b)













Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












Acknowledgments


References



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



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