聚乳酸/环氧大豆油共混物的性能

聚乳酸（PLA）与环氧大豆油（ESO）经熔融共混制得具有高韧性的PLA/ESO共混物,并研究了ESO含量对PLA微观形态、力学和流变性能的影响规律。结果表明：ESO可显著降低PLA的熔体黏度,提高PLA的韧性;PLA/ESO共混物在低ESO含量（10%）时为部分相容,而在高ESO含量（20%和30%）时发生了相分离,从而使共混物的断裂伸长率和冲击强度随ESO含量增加先增大后减小,且分别在ESO含量为20%和15%时达到最大值,约为PLA的17倍和2.9倍,而拉伸强度则随之减小。     

SEBS-g-MAH增韧聚乳酸的性能研究

采用哈克密炼机制备了聚乳酸(PLA)与马来酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚弹性体(SEBS-g-MAH)的共混物,并对共混物的力学性能、流变性能和微观结构进行了分析。结果表明,共混物的拉伸强度随着SEBS-g-MAH含量的增加而下降,断裂伸长率随着SEBS-g-MAH含量的增加而增大。当SEBS-g-MAH的含量为30 %时,共混物的冲击强度提高了2.5倍,共混物的韧性得到提高。随着SEBS-g-MAH含量的增加,PLA熔体黏度的变化趋势与SEBS-g-MAH越来越相似,即熔体黏度随着频率的增大而下降。扫描电镜分析表明,MAH基团改善了两相间的界面作用,增韧作用明显。     

不同分子量PCL增韧PLA的结构与性能

采用两种不同分子量的聚(ε-己内酯)(PCL)(粘均分子量60 000和3 000)与聚乳酸(PLA)在175℃下共混10 min制备PLA/PCL共混物。通过动态流变、扫描电子显微镜(SEM)和力学性能等研究了PLA/PCL共混物的结构和性能。动态流变显示,在PCL低含量(质量分数小于15%)时,PCL与PLA是相容的,质量分数为15%时PCL与PLA表现出明显的相分离行为。SEM显示,随着PCL含量的增加,PCL相的尺寸变大;低分子量PCL(L-PCL)的相尺寸明显大于高分子量PCL(H-PCL),而且相形态不是规则的球状。随着PCL含量的增加,共混物的拉伸强度下降,而断裂伸长率增加。当H-PCL质量分数为8.3%时,PLA/H-PCL共混物的断裂伸长率为137.32%。当H-PCL质量分数为15%时,其断裂伸长率高达232.76%。在添加相同含量PCL时,PLA/H-PCL共混物的拉伸强度高于PLA/L-PCL;而PCL质量分数8%时,共混物的断裂伸长率相差不多,当PCL质量分数大于8%时,PLA/H-PCL共混物的断裂伸长率明显比PLA/L-PCL共混物的高。     

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.     

茶粉/聚乳酸复合材料的增韧改性

为高值化利用茶产业剩余物资源,以茶粉（TD）为生物质填料,聚乳酸（PLA）为基体,以甘油（GL）、聚乙二醇400（PEG400）、环氧大豆油（ESO）和乙酰柠檬酸丁酯（ATBC）为增塑剂,制备了可降解TD/PLA增韧复合材料,并采用红外吸收光谱、热重分析、转矩流变仪、扫描电镜及力学性能测试等考察了增塑剂对TD/PLA复合材料结构与性能的影响。结果表明：4种增塑剂都可改善TD/PLA复合材料的加工流变性,GL的添加不利于复合材料韧性,PEG、ATBC及ESO的添加提高了复合材料韧性,其中ESO增韧效果最佳,其添加制备的复合材料断裂伸长率及缺口冲击强度分别提高了154.23%和65.53%,GL增韧效果最差,ATBC增韧后复合材料力学强度和模量最高。FTIR分析表明,ATBC和ESO可与PLA发生一定相互作用,使C-O键红外吸收峰位增大,其增韧后复合材料吸水率下降。ESO添加提高了TD/PLA复合材料的维卡软化点和热稳定性。SEM图片显示,TD/PLA/ESO复合材料断面粗糙,ESO分散较均匀,与PLA部分相容,而TD/PLA/GL复合材料断面出现严重相分离结构。该研究结果可为进一步探索聚乳酸基茶塑复合材料制备及应用提供试验数据和理论参考。     

Thermal,mechanical and rheological properties of poly (lactic acid)/epoxidized soybean oil blends

Summary  Poly(lactic acid) (PLA) was melt blended with epoxidized soybean oil (ESO) in an internal mixer and thermal, mechanical and rheological properties of the blends were investigated by means of differential scanning calorimetry, dynamic mechanical analysis, tensile test and small amplitude oscillatory shear rheometry. ESO lowered glass transition temperature and increased the ability of PLA to cold crystallization. The blend exhibited improved elongation-at-break along with a plastic deformation. The plasticization effect by ESO was also manifested by the lowering of dynamic storage modulus and viscosity in the melt state of the blends compared with neat PLA.     

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。     

Plasticizing effect of coconut oil on morphological,mechanical, thermal,rheological, barrier,and optical properties of poly(lactic acid): A promising candidate for food packaging

This study explores the plasticizing effect of coconut oil (CO) on PLA for evaluating its suitability for flexible packaging. Changes in morphological, mechanical, thermal, rheological, barrier and optical properties of melt compounded Poly(lactic acid)–Coconut oil (PLA–CO) blend were investigated by varying the mixing ratio. Water vapor permeability of blends decreased by 58% at 7 wt % plasticizer content. The tensile strength showed a decreasing trend with increasing plasticizer percentage while the % elongation showed an increasing trend. At 7 wt % plasticizer content tensile strength decreased from 60 to 41 MPa and % elongation increased from 12% to 54%. Molecular weight (M_n) and onset of degradation (T_onset), upon 1 wt % plasticizer addition showed a reduction of 6% and 0.6%, respectively, which were well within permissible limits required for polymer processing. The melt flow properties of the blends were slightly improved (～16%) upon 5 wt % addition of CO. Transparency of the PLA films was improved by addition of plasticizer. FTIR spectra of PLA‐CO sample confirmed the interaction between PLA and coconut oil via hydrogen bonding. At higher loading, coconut oil shows very limited compatibility with PLA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45390.     

EVA熔体流动速率对PLA/EVA共混物性能的影响

通过熔融共混法制备了聚乳酸（PLA）/乙烯-乙酸乙烯酯共聚物（EVA）共混物,采用SEM、DSC、旋转流变仪等研究了VA质量分数为28%,熔体流动速率（MFR）不同的EVA对PLA/EVA共混物性能的影响。结果表明,EVA熔体流动速率越小,其在PLA基体中分散越均匀,EVA颗粒粒径也越小。共混物的结晶度随EVA熔体流动速率的增大而增大,但PLA的玻璃化转变温度（Tg）基本不受EVA的影响。PLA/EVA共混物的复数黏度和储能模量均随EVA的熔体流动速率的增高而减小。力学性能测试结果表明,当EVA的质量分数为15%时,PLA的断裂伸长率明显升高,冲击强度约是纯PLA的2倍。     

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。     

PLA/PPC/OMMT纳米复合材料的结构与性能研究

采用双螺杆挤出机制备了聚乳酸（PLA）/聚碳酸亚丙酯（PPC）共混物和PLA/PPC/有机改性蒙脱土（OMMT）纳米复合材料,采用偏光显微镜、差示扫描量热仪和力学性能试验机等对共混物和纳米复合材料的相态结构、熔融与结晶行为和力学性能等进行了研究。结果表明,在PPC含量低于30 %时,随着PPC含量的增加,PLA/PPC和PLA/PPC/OMMT体系中PLA的玻璃化转变温度（Tg）均降低,在PPC含量为50 %时出现了明显的相分离;随着PPC含量的增加,PLA/PPC的冲击强度增大;OMMT的含量小于1.5 %时,PLA/PPC/OMMT体系的结晶度、拉伸强度、断裂伸长率和冲击强度均随OMMT含量的增加而增大。     

Mechanical properties of poly(lactic acid) and wheat starch blends with methylenediphenyl diisocyanate

Poly(lactic acid) (PLA) and wheat starch are biodegradable polymers derived from renewable sources. A previous study showed that thermally blending starch and PLA in the presence of methylenediphenyl diisocyanate (MDI) enhanced the mechanical properties of the blends. In this work, blends of PLA with various levels of wheat starch and MDI were hot mixed at 180°C then hot‐pressure molded at 175°C to form test specimens. The blends were characterized for mechanical properties, fracture microstructure, and water absorption. Pure PLA had a tensile strength of 62.7 MPa and elongation of 6.5%. The blend with 45% wheat starch and 0.5 wt % MDI gave the highest tensile strength of about 68 MPa with about 5.1% elongation. The blend with 20% starch and 0.5 wt % MDI had the lowest tensile strength of about 58 MPa with about 5.6% elongation. Dynamic mechanical analysis showed that storage modulus increased and tan δ decreased as starch level increased, but almost leveled off when starch level reached 45% or higher. Water absorption of the blends increased significantly with starch content. Yet the blend, if water proofed on its surface, has potential for short‐term disposable applications. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1257–1262, 2002; DOI 10.1002/app.10457     

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     

聚乳酸/尼龙11/氯醚弹性体三元共混体系结构与性能研究

以生物基尼龙11(PA11)和氯醚橡胶(ECO)作为聚乳酸(PLA)的增韧和耐热改性剂,通过熔融共混的方法制备了PLA/PA11/ECO三元共混体系,并系统表征了体系的相容性、形貌结构、热行为及物理性能.PA11的存在改善了共混体系组分之间相容性.连续相PA11能有效提高PLA基体的维卡软化温度至160 ℃以上.PLA...     

环氧类增容剂反应增容PLA/PBAT共混体系的研究

以环氧类增容剂(REC)为增容剂,采用双螺杆挤出机熔融共混制备聚乳酸(PLA)/聚对苯二甲酸己二酸丁二醇酯(PBAT)共混物。研究了增容剂对共混体系微观结构、力学性能和热性能的影响。结果表明,添加适量REC可以提高PLA与PBAT的相容性,改善PLA/PBAT共混体系的综合力学性能;REC用量为1.4份时共混体系呈现出良好的相容性,此时共混物冲击强度由268 kJ/m2增加到621 kJ/m2、断裂伸长率提高由222 %增加到357 %。     

The effect of MBS on the heat resistant,mechanical properties,thermal behavior and rheological properties of PLA/EVOH blend

This work focuses on improve the mechanical properties of poly(lactic acid)/poly(ethylene-co-vinyl alcohol) (PLA/EVOH) blend and simultaneously remained a high Vicat softening temperature (VST) using appropriate contents of methyl methacrylate–butadiene–styrene copolymer (MBS) via simple melt blending. The effects of MBS on the heat resistant, mechanical properties, thermal properties and rheological behavior were examined in detail with various techniques. The VST of neat PLA significantly increased to 159 °C from 66.8 °C after blending with 50 wt% EVOH. However, the VST was gradually decreased with increasing MBS content but were still much higher than that of neat PLA. On the basis of the tensile and impact tests results, PLA/EVOH/MBS blends showed a considerably higher elongation at break and impact strength. For all PLA/EVOH/MBS blends, the thermal stability was increased compared than that of PLA/EVOH blend without MBS. With increasing MBS content, the complex viscosity and storage modulus of PLA/EVOH blend increased, especially at low frequencies, indicating that MBS enhanced the chain entanglement in the PLA/EVOH matrix. In addition, the results Han curves and Cole–Cole plots indicated that the relaxation time was increased when MBS was added.     

Rheological and mechanical characterization of poly(lactic acid)/polypropylene polymer blends

Poly(lactic acid) (PLA) was melt blended with polypropylene (PP) with the aim of replacing commodity polymers in future applications. Since cost of PLA is quite high, it is not economically feasible to use it alone for day to day use as a packaging material without blending. This paper reports the preparation of poly(lactic acid)/polypropylene polymer blends (PLA/PP) using a laboratory scale single screw extruder. Rheological and mechanical properties of the prepared blends were determined. The rheological experiments were carried out on a capillary rheometer, the effect of shear rate, temperature and PLA content on the flow activation energy and true viscosity of the blends were described. Mechanical properties of the blends were investigated on dog bone-shaped samples obtained by injection molding; tensile tests were performed using Testometric M350-10KN. The effect of PLA content on Young’s modulus, strain at break and stress at break of the blends were described. The rheological results showed that the true viscosity of the blends is between that of the pure polymers, whereas the flow activation energy of the blends is less than that of the pure polymers. The mechanical results showed incompatibility between PLA and PP in the blend.     

PBAT/PLA薄膜的制备及性能研究

将聚乳酸（PLA）和聚对苯二甲酸-己二酸-丁二醇酯（PBAT）共混制备成共混材料,探讨了不同PLA含量对材料性能的影响。结果表明,PBAT/PLA共混材料中,随着PLA含量的增加,拉伸强度先降低后升高,当PLA含量为90 %时,拉伸强度达到60.12 MPa,而其断裂伸长率从703 %降低至8 %,由韧性材料逐渐转变为脆性材料;PLA含量为30 %时,性能变化出现拐点;PLA含量为50 %时出现明显相分离,且PLA的加入可以加速PBAT材料的结晶,使结晶温度由38 ℃提高至82 ℃;PBAT/PLA共混材料在PLA含量低于70 %时,都可以实现较好的吹膜过程,且薄膜材料的拉伸强度为39.59 MPa,断裂伸长率不低于137 %。     

Poly (ethylene oxide) (PEO) influence on mechanical,thermal, and degradation properties of PLA/PBSeT blends

Poly (lactic acid) (PLA) is an important biodegradable plastic with unique properties. However, its widespread application is hindered by its low miscibility and suboptimal degradation properties. To overcome these limitations, we investigated the mechanical, thermal, and degradation properties of PLA and poly (butylene sebacate-co-terephthalate) (PBSeT) blends in the presence of poly (ethylene oxide) (PEO). Specifically, this study aimed to identify the effects of PEO as a compatibilizer and hydrolysis accelerator in PLA/PBSeT blends. PLA (80%) and PBSeT (20%) were melt blended with various PEO contents (2–10 phr), and their mechanical, thermal, and hydrolytic properties were analyzed. All PEO-treated blends exhibited a higher elongation at break than that of the control sample, and the tensile strength was slightly reduced. In the PEO 10% sample, the elongation at break increased to 800% of that of the control sample. Differential scanning chromatography (DSC) analysis confirmed that when PEO was added to the PLA/PBSeT blends, the two glass transition temperatures (T_g) narrowed, resulting in improved miscibility of PLA and PBSeT. In addition, the hydrolytic degradation of the PLA/PBSeT/PEO blend accelerated as the PEO content increased. It was confirmed that PEO can act as a compatibilizer and hydrolysis-accelerating agent for PLA/PBSeT blends.     

异氰酸酯对聚乳酸/热塑性聚氨酯共混物性能的影响

以4,4^′-二苯基甲烷二异氰酸酯（MDI）为反应增容剂，采用熔融共混法制备了不同MDI含量的聚乳酸/热塑性聚氨酯（PLA/TPU）共混物，采用傅里叶变换红外光谱仪（FTIR）、万能试验机、冲击试验机、扫描电子显微镜（SEM）、差示扫描量热仪（DSC）和旋转流变仪对共混物力学性能、微观形态、热性能和流变性能进行了研究。结果表明：MDI可以有效改善共混物的力学性能，当MDI质量分数为1%时，共混物力学性能最佳，缺口冲击强度为40.0kJ/m²，断裂伸长率为214.1%，与未加MDI的共混物相比，分别增加了4.3倍和5.8倍，拉伸强度稍有下降（47.6MPa）；SEM表明，MDI的加入提高了共混物的相容性，加入MDI后，共混物的断面由海-岛结构变为核-壳包覆结构，相界面作用力增强；DSC测试表明，共混物的玻璃化转变温度、冷结晶温度和熔融温度随着MDI含量的增加而升高；流变测试表明，MDI质量分数的增加，共混物呈现更显著的剪切变稀行为，推测共混反应机理为：MDI质量分数的增加，体系内依次发生PLA的扩链、支化和TPU的交联。