Agüero Ángel, Garcia-Sanoguera David, Lascano Diego, Rojas-Lema Sandra, Ivorra-Martinez Juan, Fenollar Octavio, Torres-Giner Sergio
Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV), Plaza Ferrándiz y Carbonell 1, 03801 Alcoy, Spain.
Escuela Politécnica Nacional, 17-01-2759 Quito, Ecuador.
Polymers (Basel). 2020 Apr 4;12(4):821. doi: 10.3390/polym12040821.
Green composites made of polylactide (PLA) and short flaxseed fibers (FFs) at 20 wt % were successfully compounded by twin-screw extrusion (TSE) and subsequently shaped into pieces by injection molding. The linen waste derived FFs were subjected to an alkalization pretreatment to remove impurities, improve the fiber surface quality, and make the fibers more hydrophobic. The alkali-pretreated FFs successfully reinforced PLA, leading to green composite pieces with higher mechanical strength. However, the pieces also showed lower ductility and toughness and the lignocellulosic fibers easily detached during fracture due to the absence or low interfacial adhesion with the biopolyester matrix. Therefore, four different compatibilization strategies were carried out to enhance the fiber-matrix interfacial adhesion. These routes consisted on the silanization of the alkalized FFs with a glycidyl silane, namely (3-glycidyloxypropyl) trimethoxysilane (GPTMS), and the reactive extrusion (REX) with three compatibilizers, namely a multi-functional epoxy-based styrene-acrylic oligomer (ESAO), a random copolymer of poly(styrene--glycidyl methacrylate) (PS--GMA), and maleinized linseed oil (MLO). The results showed that all the here-tested compatibilizers improved mechanical strength, ductility, and toughness as well as the thermal stability and thermomechanical properties of the green composite pieces. The highest interfacial adhesion was observed in the green composite pieces containing the silanized fibers. Interestingly, PS--GMA and, more intensely, ESAO yielded the pieces with the highest mechanical performance due to the higher reactivity of these additives with both composite components and their chain-extension action, whereas MLO led to the most ductile pieces due to its secondary role as plasticizer for PLA.
由聚乳酸（PLA）和20重量%的短亚麻籽纤维（FFs）制成的绿色复合材料通过双螺杆挤出（TSE）成功复合，随后通过注塑成型制成片材。将亚麻废料衍生的FFs进行碱化预处理，以去除杂质、改善纤维表面质量并使纤维更具疏水性。碱预处理的FFs成功增强了PLA，从而得到具有更高机械强度的绿色复合材料片材。然而，这些片材的延展性和韧性也较低，并且由于与生物聚酯基体缺乏或界面粘合力低，木质纤维素纤维在断裂时容易分离。因此，采用了四种不同的增容策略来增强纤维-基体界面粘合力。这些方法包括用缩水甘油基硅烷，即（3-缩水甘油氧基丙基）三甲氧基硅烷（GPTMS）对碱化的FFs进行硅烷化处理，以及用三种增容剂进行反应挤出（REX），这三种增容剂分别是多功能环氧基苯乙烯-丙烯酸低聚物（ESAO）、聚（苯乙烯-甲基丙烯酸缩水甘油酯）（PS-GMA）无规共聚物和马来酸化亚麻籽油（MLO）。结果表明，所有在此测试的增容剂都改善了绿色复合材料片材的机械强度、延展性和韧性以及热稳定性和热机械性能。在含有硅烷化纤维的绿色复合材料片材中观察到最高的界面粘合力。有趣的是，PS-GMA以及更显著的ESAO由于这些添加剂与两种复合材料组分的更高反应性及其扩链作用，使片材具有最高的机械性能，而MLO由于其作为PLA增塑剂的次要作用，使片材具有最大的延展性。
