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首页> 外文OA文献 >Mechanical, thermal and morphological properties of montmorillonite filled linear low density polyethylene-toughened polylactic acid nanocomposites
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Mechanical, thermal and morphological properties of montmorillonite filled linear low density polyethylene-toughened polylactic acid nanocomposites

机译：蒙脱土填充的线性低密度聚乙烯增韧聚乳酸纳米复合材料的力学，热学和形态学性能

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摘要

Linear low density polyethylene (LLDPE) toughened polylactic acid (PLA) nanocomposites containing organophilic modified montmorillonite (MMT) were prepared by melt extrusion using a counter-rotating twin-screw extruder followed by injection molding in order to examine the mechanical, morphological and thermal properties of the nanocomposites. The mechanical properties of PLA/LLDPE nanocomposites were studied through tensile, flexural and impact tests. Scanning electron microscopy (SEM) was used to investigate the phase morphology and LLDPE particle’s size in PLA/LLDPE blends and nanocomposites. X-ray diffraction (XRD) was employed to characterize the formation of nanocomposites while the thermal properties were determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dynamic mechanical properties were examined via dynamic mechanical analysis (DMA) while moisture permeability properties of the PLA/LLDPE nanocomposites were assessed through water absorption and hygrothermal aging. Subsequently, for PLA/LLPDE blends, the loadings of LLPDE were varied from 5-15 wt% and PLA/LLDPE nanocomposites with 2 phr and 4 phr loadings of MMT were prepared only for the optimum formulation (10 wt% of LLDPE). The results showed that the blending of LLDPE significantly increased the toughness but at the expense of stiffness and strength. Conversely, the incorporation of the MMT increased the stiffness, while the toughness and strength decreased. The PLA/LLDPE nanocomposites containing 2 phr of MMT and 10 wt% of LLDPE had the best balance of stiffness, strength and toughness. The impact strength results also proved that PLA nanocomposites were successfully toughened with LLDPE. XRD established that MMT were well dispersed and preferentially embedded in the PLA phase. SEM revealed that blend ratio and the presence of MMT were found to influence the morphology (e.g. LLDPE particle size and distribution) of the system. Finer particles’ size and better distribution of LLDPE has been observed in higher MMT loadings in the system. The SEM micrographs also revealed that increasing content of LLDPE has increased the particle size of LLDPE in PLA. DMA analysis discovered that the storage modulus at 30ºC increased with the presence of MMT for PLA nanocomposites. The DSC results showed that the crystallization temperature (Tc) dropped gradually with increasing content of MMT for both PLA and PLA/LLDPE nanocomposites while the glass transition (Tg) and melting temperature (Tm) remained unchanged. TGA also exhibited an increase in T10% decomposition temperature for PLA and PLA/LLDPE nanocomposites. Water absorption curves obeyed the Fick’s law with rapid moisture absorption to maximum saturation level (Mm) and the value of Mm of PLA increased with addition of LLDPE and 2 phr of MMT. Hygrothermal aging revealed that the Mm increased significantly at elevated temperatures (60ºC and 90ºC) and addition of LLDPE and MMT improved the hygrothermal stability of PLA.
机译：通过使用反向旋转双螺杆挤出机进行熔体挤出，然后注塑成型，来制备含有亲有机改性蒙脱土（MMT）的线性低密度聚乙烯（LLDPE）增韧聚乳酸（PLA）纳米复合材料，以检查其机械，形态和热性能纳米复合材料。通过拉伸，弯曲和冲击试验研究了PLA / LLDPE纳米复合材料的力学性能。扫描电子显微镜（SEM）用于研究PLA / LLDPE共混物和纳米复合材料中的相形态和LLDPE粒径。 X射线衍射（XRD）用于表征纳米复合材料的形成，同时使用热重分析（TGA）和差示扫描量热法（DSC）确定热性能。通过动态力学分析（DMA）检查了动态力学性能，同时通过吸水和湿热老化评估了PLA / LLDPE纳米复合材料的透湿性。随后，对于PLA / LLPDE共混物，LLPDE的负载量为5-15 wt％，并且仅针对最佳配方（10 wt％的LLDPE）制备了具有2 phr和4 phr MMT负载的PLA / LLDPE纳米复合材料。结果表明，LLDPE的共混可以显着提高韧性，但会牺牲刚度和强度。相反，MMT的加入增加了刚度，而韧性和强度却降低了。包含2 phr的MMT和10 wt％的LLDPE的PLA / LLDPE纳米复合材料在刚度，强度和韧性方面达到最佳平衡。冲击强度结果还证明，LLDPE成功地增韧了PLA纳米复合材料。 XRD确定MMT分散良好，并优先嵌入PLA阶段。 SEM显示，发现混合比例和MMT的存在会影响体系的形态（例如LLDPE粒径和分布）。在系统中较高的MMT负载下，可以观察到更细的颗粒尺寸和LLDPE更好的分布。 SEM显微照片还显示，增加LLDPE的含量增加了PLA中LLDPE的粒径。 DMA分析发现，对于PLA纳米复合材料，MMT的存在会增加30ºC时的储能模量。 DSC结果表明，随着PLA和PLA / LLDPE纳米复合材料MMT含量的增加，结晶温度（Tc）逐渐降低，而玻璃化转变温度（Tg）和熔融温度（Tm）保持不变。对于PLA和PLA / LLDPE纳米复合材料，TGA还显示出T10％分解温度的升高。吸水曲线符合菲克定律，吸水迅速，达到最大饱和水平（Mm），并且当添加LLDPE和2 phr MMT时，PLA的Mm值增加。湿热老化表明，在高温（60ºC和90ºC）下Mm显着增加，并且添加LLDPE和MMT改善了PLA的湿热稳定性。

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  • 作者

    Balakrishnan Harintharavimal;

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  • 年度 2010
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  • 原文格式 PDF
  • 正文语种 {"code":"en","name":"English","id":9}
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