PLA/PVA复合材料的制备与性能

以聚乳酸(PLA)、热塑性聚乙烯醇(PVA)为原料,采用熔融共混法制备了热塑性PLA/PVA复合材料。通过万能试验机、冲击试验机、熔体流动速率测试仪及扫描电子显微镜对复合材料的拉伸性能、冲击性能、流动性能及微观形貌进行了表征。结果表明:随着热塑性PVA含量的增加,复合材料的拉伸强度及断裂伸长率呈下降趋势;冲击强度及熔体流动速率呈先增加后下降趋势。     

聚乳酸与高分子弹性体共混体系的研究

研究了聚乳酸（PLA）与高分子弹性体共混体系的微观结构、力学性能和结晶性能。结果表明,PLA/弹性体共混体系亚微观不相容;弹性体含量为40 %（质量分数,下同）时与PLA的相容性较好;加入弹性体后,PLA在升温过程中,当温度到达110 ℃时发生了诱导结晶;随着弹性体含量的增加,PLA/弹性体共混体系的塑化时间减小,熔体流动速率增加,断裂伸长率大大增加但同时拉伸强度下降。     

丙烯酸酯增韧聚乳酸的制备与性能

采用1,6-己二醇二丙烯酸酯(HDDA)和聚乳酸(PLA)为原料,通过反应共混法制备了PLA/HDDA共混物,并利用拉力试验机、冲击试验机、扫描电子显微镜、差式扫描量热仪和偏光显微镜研究了HDDA含量对共混物力学性能、断面形貌、热性能和结晶性能的影响。结果表明,HDDA对PLA具有良好的增韧效果,随着HDDA含量的增加,共混物的断裂伸长率和冲击强度显著提高;当HDDA含量为20%时,冲击强度达到8. 2 kJ/m~2,断裂伸长率为62. 8%,而拉伸强度仍保持在较高水平(39. 8 MPa)。HDDA的加入使共混物的冲击断面变粗糙,断裂形态为韧性断裂;随着HDDA含量的增加,共混物中PLA相的玻璃化转变温度逐渐降低,冷结晶温度先升高后降低,结晶度则先减小后增大。     

ABS高胶粉增韧PLA合金材料的研究

研究了不同配方体系的丙烯腈-丁二烯-苯乙烯共聚物(ABS)高胶粉/聚乳酸(PLA)共混合金的力学性能、熔体流动性、注塑加工性,并通过SEM、DMA对ABS高胶粉/PLA共混合金的微观结构、相容性进行了表征。结果表明:ABS高胶粉大大提高了PLA的冲击强度和断裂伸长率,但拉伸强度和模量有所降低;增加ABS高胶粉含量,合金熔体流动性能、注塑加工性能均呈下降趋势;当ABS高胶粉质量分数为10%时,合金的熔体质量流动速率与纯PLA相当,熔体流动性较好,tanδ谱图和SEM照片也表征:此配方体系下的合金相容效果最佳。     

丙烯酸酯接枝改性天然橡胶增韧聚乳酸

通过在天然橡胶(NR)分子链上接枝甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA),制备了三种丙烯酸酯接枝改性NR:NR-g-PMMA,NR-g-PBA和NR-g-(PMMA,PBA)。采用核磁共振氢谱对三种接枝物进行了化学结构鉴定。将接枝改性后的NR和未改性的NR与PLA采用哈克密炼机熔融共混,分别制备了PLA/NR,PLA/NR-gPMMA,PLA/NR-g-PBA和PLA/NR-g-(PMMA,PBA)共混物,研究了接枝改性NR和未改性NR含量对共混物力学性能和热性能的影响。各共混物的拉伸弹性模量和拉伸强度均随接枝改性NR和未改性NR含量的增加而降低,断裂伸长率和缺口冲击强度随接枝改性NR和未改性NR含量的增加而提高。其中,PLA/NR-g-PBA共混物的断裂伸长率和缺口冲击强度比其它共混物提高的幅度大,当NR-g-PBA的质量分数为5%时,PLA/NR-g-PBA共混物的断裂伸长率达到78%,缺口冲击强度为5.2 k J/m2,而纯PLA的断裂伸长率仅为7.7%,缺口冲击强度为2.5 k J/m2,说明NR接枝分子柔顺性较高的BA更有利于促进其与PLA共混物的韧性提高。热分析结果表明,PLA/NR-gPBA共混物的热稳定性相比于纯PLA也有所提高。     

等温冷结晶对PLA/PBAT共混物冲击韧性和耐热性能的影响

通过熔融共混法制备了聚乳酸/聚己二酸-对苯二甲酸丁二醇酯(PLA/PBAT)共混物,并对其微观形貌、热性能、冲击性能和耐热性能进行了研究。结果表明,随着PLA/PBAT共混物中PBAT含量的增加,共混材料的无缺口冲击强度逐渐增大,其中当PBAT含量为30%时,共混材料的无缺口冲击强度达到最大值。再通过等温冷结晶提高PLA/PBAT材料的结晶度,以改善材料的耐热性能。结果表明,等温冷结晶样品的维卡软化温度(VST)明显高于急冷样品,且结晶度越高,VST值则越大;此外,90℃等温冷结晶20 min的样条无缺口冲击强度高于急冷样条,但当等温冷结晶温度提高至130℃时,样条的无缺口冲击强度下降,且低于急冷样条。因此,较低冷结晶温度有利于得到兼具良好耐热性能和冲击性能的PLA/PBAT材料。     

高韧性聚乳酸/弹性体共混材料结构与性能研究

通过熔融挤出-热拉伸-淬冷方法制备了不同马来酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯(SEBS-g-MAH)含量的聚乳酸(PLA)/SEBS-g-MAH共混材料。通过熔体流动速率测定仪、扫描电镜、转矩流变仪等研究SEBSg-MAH含量对共混材料加工稳定性、相容性、流变行为及力学性能的影响。研究结果表明:PLA中加入热塑性弹性体SEBS-g-MAH时,两相具有一定的相容性;共混材料流动性增大,加工稳定性得到提升。力学性能测试结果表明:随着SEBS-g-MAH含量的增加,共混材料的缺口冲击强度和断裂伸长率都呈现先增大后减小的趋势,SEBS-g-MAH加入量为15%时,共混材料缺口冲击强度和断裂伸长率分别达到最大值5.67k J/m2和20.51%,较纯PLA分别增加了78%和137%。     

PLA/PBAT质量配比对PLA/PBAT/CaCO_3共混体系的影响

通过熔融共混制备了 PLA/PBAT/CaCO_3共混体系,研究了不同PLA/PBAT质量配比对共混体系力学性能、流变学性能和熔融、结晶性能的影响。结果表明:随着PBAT用量的增加,共混体系拉伸强度、弯曲强度、弯曲模量和密度下降,断裂伸长率、冲击强度增加,并在PLA/PBAT质量配比为35/35左右时冲击强度大幅度增加;共混体系黏度随PBAT用量增加呈现先下降后上升趋势,并在PLA/PBAT质量配比为56/14时黏度达到最低;DSC显示,随PBAT用量增加,熔融温度逐渐降低,结晶温度逐渐增高,且在PLA/PBAT质量配比不超过56/14时无结晶出现。     

原位反应法制备聚乳酸/聚氨酯共混物及性能

以聚乳酸（PLA）、聚四氢呋喃醚二醇（PTMG）和液化4,4′-二苯基甲烷二异氰酸酯（L-MDI）为原料,通过原位反应法制备了PLA/聚氨酯（PU）共混物,研究了PLA/PU共混物的反应原理、力学性能、断面形貌、动态流变性能以及结晶性能。结果表明,在原位反应中有微交联结构PU生成,且伴随着PLA的扩链和枝化反应;PLA/PU共混物的韧性得到显著提高,当PU含量为30 %（质量分数,下同）时,共混物的断裂伸长率、断裂韧性和缺口冲击强度分别达到230 %、134.13 MJ/m3和34.19 kJ/m2,较纯PLA分别增加了16.6、8.1和11.1倍,此时拉伸强度仍保持在较高水平（49.7 MPa）;纯PLA和PLA/PU共混物熔体均为假塑性流体,共混物具有更高的储能模量和复数黏度;PLA/PU共混物比纯PLA的结晶速率高,晶体完善程度高。     

聚乳酸增塑体系熔体流动性及力学性能研究

通过熔融共混法,分别以乙酰柠檬酸三丁酯(ATBC)、己二酸二丁基二甘酯(增塑剂A)、异山梨醇硬脂酸酯(增塑剂B)、癸二酸二丁酯(DBS)为增塑剂,以丙烯酸型抗冲改性剂为增韧剂,制备了增塑聚乳酸(PLA)和复配增塑增韧PLA,研究了复配改性PLA的熔体流动性和力学性能,考察了增韧剂对PLA增塑体系的影响。结果表明:增塑剂A增塑PLA的综合性能较好;增韧剂可有效降低材料的熔体流动速率,提高材料的缺口冲击强度和断裂伸长率,但其拉伸强度有所降低。     

Effect of glycidyl methacrylate-grafted natural rubber on physical properties of polylactic acid and natural rubber blends

Natural rubber (NR) was melt blended with polylactic acid (PLA) at various ratios using an internal mixer. The impact strength and elongation at break of PLA/NR blend dramatically increased with increasing NR content up to 10% (w/w). Glycidyl methacrylate-grafted natural rubber (NR-g-GMA) was used as a compatibilizer for PLA/NR blend. The effects of content and %grafting of NR-g-GMA on mechanical properties of PLA/NR blend were studied. The experimental result showed that the addition of NR-g-GMA in PLA/NR blend significantly improved impact strength and elongation at break of PLA/NR blend when compared with that of neat PLA and PLA/NR blend without NR-g-GMA. The impact strength and elongation at break of PLA/NR blend increased with increasing NR-g-GMA content up to 1% (w/w). Moreover, with increasing % grafting of NR-g-GMA in PLA/NR blend up to 4.35, the impact strength and elongation at break of the blend increased. Morphological and thermal property of PLA, PLA/NR, and PLA/NR/NR-g-GMA were elucidated as well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical and rheological properties of epoxidized soybean oil plasticized poly(lactic acid)

Poly(lactic acid) (PLA) is a well known biodegradable thermoplastic with excellent mechanical properties that is a product from renewable resources. However, the brittleness of PLA limits its general applications. Using epoxidized soybean oil (ESO) as a novel plasticizer of poly(lactic acid), the composite blend with the twin‐screw plastic extruder at five concentrations, 3, 6, 9, 12, and 15 wt %, respectively. Compared with pure PLA, all sets of blends show certain improvement of toughness to different extents. The concentration with 9 wt % ESO increases the elongation at break about 63%. The melt flow rates of these blends with respect to different ESO ratio have been examined using a melt flow indexer. Rheological behaviors about shear viscosity and melt strength analysis are discussed based on capillary rheology measurements. The tensile strength and melt strength of the blends with 6 wt % ESO simultaneity reach the maximums; whereas the elongation at break of the blends is the second highest level. ESO exhibits positive effect on both the elongation at break and melt strength. The results indicate that the blend obtained better rheological performance and melt strength. The content of 6 wt % ESO in PLA has been considered as a better balance of performance. The results have also demonstrated that there is a certain correlation between the performance in mechanical properties and melt rheological characterization for the PLA/ESO blends.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

苹果酸对聚乳酸/热塑性淀粉共混物结构与性能的影响

将天然淀粉用甘油改性后制得了热塑性淀粉(TPS),再通过熔融共混法制备了聚乳酸(PLA)/TPS共混物。通过SEM、TG、DSC分析和拉伸性能、吸水性能、流变性能测试,研究了苹果酸对TPS和PLA/TPS共混物结构和性能的影响。结果表明:苹果酸能促进淀粉酸解,使TPS分散相尺寸减小,在PLA基体中的分布更加均匀;苹果酸能提高PLA/TPS共混物的拉伸性能;苹果酸对PLA/TPS共混物的玻璃化转变温度、熔融温度及冷结晶温度影响较小;少量的苹果酸可降低PLA/TPS共混物的吸水率。     

完全生物降解塑料PLA/PPC合金的结构与性能研究

利用机械共混法,将聚乳酸(PLA)与聚丙撑碳酸亚丙酯(PPC)熔融共混,制备了完全生物降解塑料PLA/PPC合金,并用FTIR、流变仪等手段研究了其结构、力学性能和流变性能。结果表明该共混体系具有良好的相容性、力学性能和熔体流动性,PLA与PPC之间存在着较强的相互作用,PPC的加入使体系拉伸强度下降幅度不大,断裂伸长率升高到23.8%,比纯PLA提高近20倍。共混体系的黏度亦随着PPC的加入逐渐增大,PLA/PPC(50/50)体系的黏流活化能为37.1kJ/mol,同时在一定的温度范围内,提高切应力也会使体系黏度下降。     

Poly(lactic acid)/ethylene vinyl acetate copolymer blend composites with wood flour and wollastonite: Physical properties,morphology, and biodegradability

In the present study, poly(lactic acid) (PLA), a biodegradable plastic, was melt‐blended with five weight percentages (10–50 wt%) of ethylene vinyl acetate (EVA) copolymer, a non‐biodegradable plastic, having a vinyl acetate content of 19 wt% and a melt flow index of 530 g/10 min, on a twin screw extruder, followed by an injection molding. The blends at 10 and 20 wt% EVA revealed a noticeably increased impact strength and strain at break over the pure PLA, and the blend at 10 wt% EVA exhibited the highest impact strength and strain at break. The 90/10 (wt%/wt%) PLA/EVA blend was then selected for preparing either single or hybrid composite with wood flour (WF) and wollastonite (WT). The filler loading was fixed at 30 parts by weight per hundred of resin throughout the experiment, and the WF/WT weight ratios were 30/0, 20/10, 15/15, 10/20, and 0/30. The prepared composites were examined for their mechanical and thermal properties, melt flow index, flammability, water uptake, and biodegradability as a function of composition. All the composites showed a filler‐dose‐dependent decrease in the impact strength and strain at break, but an increase in the tensile and flexural modulus (optimal at 0/30 WF/WT) and tensile and flexural strength (optimal at 30/0 WF/WT) as compared with the neat 90/10 (wt%/wt%) PLA/EVA blend. In addition, the melt flow index, char residue, anti‐dripping ability, water uptake, and biodegradability of the composites were also higher than those of the neat blend. J. VINYL ADDIT. TECHNOL., 25:313–327, 2019. © 2019 Society of Plastics Engineers     

Poly (vinyl alcohol)/polylactic acid blend film with enhanced processability,compatibility, and mechanical property fabricated via melt processing

Poly (vinyl alcohol)/polylactic acid (PVA/PLA) blend film, which is environment friendly and has potential applications in food and electronic packaging fields, was fabricated by melt extrusion casting. Fourier transform infrared spectroscopy analysis confirmed the formation of the hydrogen bonding between PLA and PVA, which improved the compatibility of PLA with PVA, making PLA uniformly dispersed in PVA matrix as small spheres, even when PLA content increase to 15 wt%. In this way, the original hydrogen bond network among PVA was disturbed and the chain mobility of PVA was activated, endowing PVA/PLA blends with lower melt viscosity than bot modified PVA and PLA, and the blend films with the increased crystallinity, mechanical property, and water resistance. Compared with PVA film, the crystallinity, tensile strength and Young's modulus of the blend film with 15 wt% PLA, respectively, increased by 15.1%, 9 and 51 MPa, and the water contact angle enlarged from 23° to 60°.     

Morphology and properties of the biosourced poly(lactic acid)/poly(ethylene oxide‐b‐amide‐12) blends

Biosourced poly(lactic acid) (PLA) blends with different content of poly(ethylene oxide‐b‐amide‐12) (PEBA) were prepared by melt compounding. The miscibility, phase structure, crystallization behavior, mechanical properties, and toughening mechanism were investigated. The blend was an immiscible system with the PEBA domains evenly dispersed in the PLA matrix. The PEBA component suppressed the nonisothermal melt crystallization of PLA. With the addition of PEBA, marked improvement in toughness of PLA was achieved. The maximum for elongation at break and impact strength of the blend reached the level of 346% and 60.5 kJ/m², respectively. The phase morphology evolution in the PLA/PEBA blends after tensile and impact tests was investigated, and the corresponding toughening mechanism was discussed. It was found that the PLA matrix demonstrates obvious shear yielding in the blend during the tensile and impact tests, which induced energy dissipation and therefore lead to improvement in toughness of the PLA/PEBA blends. POLYM. COMPOS., 2013. © 2012 Society of Plastics Engineers     

Effects of thermoplastic poly(ether-ester) elastomer and bentonite nanoclay on properties of poly(lactic acid)

This work presented the influence of thermoplastic poly(ether-ester) elastomer (TPEE) and bentonite (BTN) on improving the mechanical and thermal properties of poly(lactic acid) (PLA). PLA was initially melt mixed with TPEE at six different loadings (5–30 wt%) on a twin screw extruder and then injection molded. The mechanical tests revealed an increasing impact strength and elongation at break with increasing TPEE loading, but a diminishing Young's modulus and tensile strength with respect to pure PLA. The blend at 30 wt% TPEE provided the optimum improvement in toughness, exhibiting an increase in the impact strength and elongation at break by 3.21- and 10.62-fold over those of the pure PLA, respectively. Scanning electron microscopy analysis illustrated a ductile fractured surface of the blends with the small dispersed TPEE domains in PLA matrix, indicating their immiscibility. The 70/30 (wt/wt) PLA/TPEE blend was subsequently filled with three loadings of BTN (1, 3, and 5 parts by weight per hundred of blend resin [phr]), where the impact strength, Young's modulus, tensile strength and thermal stability of all the blends were improved, while the elongation at break was deteriorated. Among the three nanocomposites, that with 1 phr BTN formed exfoliated structure and so exhibited the highest impact strength, elongation at break, and tensile strength compared to the other intercalated nanocomposites. Moreover, the addition of BTN was found to increase the thermal stability of the neat PLA/TPEE blend due to the barrier properties and high thermal stability of BTN.     

Graphene Nanoplatelets as Novel Reinforcement Filler in Poly(lactic acid)/Epoxidized Palm Oil Green Nanocomposites: Mechanical Properties

Graphene nanoplatelet (xGnP) was investigated as a novel reinforcement filler in mechanical properties for poly(lactic acid) (PLA)/epoxidized palm oil (EPO) blend. PLA/EPO/xGnP green nanocomposites were successfully prepared by melt blending method. PLA/EPO reinforced with xGnP resulted in an increase of up to 26.5% and 60.6% in the tensile strength and elongation at break of the nanocomposites respectively, compared to PLA/EPO blend. XRD pattern showed the presence of peak around 26.5° in PLA/EPO nanocomposites which corresponds to characteristic peak of graphene nanoplatelets. However, incorporation of xGnP has no effect on the flexural strength and modulus. Impact strength of PLA/5 wt% EPO improved by 73.6% with the presence of 0.5 wt% xGnP loading. Mechanical properties of PLA were greatly improved by the addition of a small amount of graphene nanoplatelets (<1 wt%).