【作者】 岑兰；

【导师】 曹有名；

【作者基本信息】 广东工业大学 ， 材料学， 2014， 博士

【摘要】 木塑复合材料相较普通木材而言有价格低廉、易成型、耐腐蚀等优点,近年来己被广泛应用于家居、板材等领域,但由于高填料填充的复合体系,在加工、成型、相容剂的选择上仍然存在较多问题。本文以BPO为引发剂,通过马来酸酐(MAH)与腰果酚缩水甘油醚(GPPE)反应,制备马来酸酐-腰果酚缩水甘油醚共聚物(MGPPE),将其作为高密度聚乙烯基木塑复合材料(WF/HDPE)的增容剂,并与GPPE和常见增容剂如马来酸酐化聚乙烯(MPE)、马来酸酐化C5石油树脂(MC5)和马来酸酐接枝聚乙烯丙烯共聚物(MPOE)作为对比。文中用1H NMRr间接测定M-GPPE中MAH的转化率,进行正交实验考察各反应因素对MAH转化率的影响,得到MAH转化率最高的优化反应工艺和各反应因素对反应影响的大小顺序。同时通过FT-IR, GPC.和1H NMR证实了GPPE与MAH发生了接枝共聚反应,并推断其反应机理,得到M-GPPE的可能结构式；通过热重分析仪证明了GPPE与MAH进行接枝共聚反应有利于提高其热稳定性。通过制备MGPPE改性WF/HDPE木塑复合材料,研究不同用量的MGPPE对复合材料力学性能的影响,采用红外分析、接触角和界面微观形态分析测试手段,深入研究木塑复合材料的界面特性和探讨MGPPE对木塑复合材料的改性机理。并与常用的相容剂和GPPE的改性效果进行对比研究,以评价MGPPE对HDPE基木塑材料的增容效果。结果表明：WF/HDPE木塑复合材料中加入MGPPE,其力学性能、接触角和界面相容性均得到一定程度提高和改善,改性效果与MPE相当,但优于MC5,其中WF/HDPE木塑复合材料中加入4wt%MGPPE时增容效果最佳,力学性能提高最大。采用平板流变仪和哈克流变仪对HDPE基木塑复合材料的粘弹性和加工性能进行研究。通过小振幅振荡实验研究不同木粉含量和不同相容剂对WPCs界面结合和流变特性的影响,借助Carreau模型得到木粉用量和相容剂对牛顿指数和松弛特性影响规律,从松弛时间反映WPCs体系的多尺度松弛特性和材料结构之间的关系。结果表明：MGPPE和HDPE具有一定相容性,加入MGPPE前后WPCs的模量随应变和频率变化的规律相似；随木粉用量提高,Carreau模型n值减小,复合材料的剪切变稀行为加强,而加入相容剂对n值影响不大。WPCs样品的松弛时间均高于纯HDPE,木粉用量越高,WPCs的松弛时间越长；加入MGPPE或MPE后,相应复合材料的松弛时间均有所缩短。加入MGPPE使复合材料的应力松弛时间延长,试样长时承载能力有所提高,同时最大扭矩和平衡扭矩均有所降低,有利于提高加工性能。此外通过DSC并结合XRD,进一步研究了WPCs的结晶行为,并通过Avrami方程,分析了木粉含量、相容剂及木粉网络结构对HDPE基体的结晶动力学参数及热力学参数的影响,并讨论了WPCs体系中影响HDPE结晶行为和结晶过程的主要因素。结果表明：木粉和相容剂的加入没有改变HDPE的结晶行为,但在结晶过程促进晶粒细化；WPCs样品具有比HDPE更高的Tc和Xc,更低的Tm,说明木粉粒子具有异相成核作用,并对HDPE晶体生长有一定限制作用；添加相容剂后复合材料的结晶温度和结晶度有所提高,熔点有所降低,当木粉用量和MGPPE用量分别为40wt%和6wt%时,复合材料熔点的降低程度变小,说明在高木粉填充量下,MGPPE能改善PE/木粉两相界面粘合,促进晶体完善。加入相容剂后复合材料的Avrami指数n值有所降低,t1/2变长,K值相对较小,说明相容剂通过促进木粉分散,加强了木粉异相成核程度。最后研究木粉用量、浸泡温度和改性剂对复合材料吸湿特性的影响。从水分输送动力学方面,考察WPCs吸水率、水分扩散速率和扩散系数的变化情况,从水分输送热力学方面考察WPCs的扩散活化能特征,通过研究复合材料的吸水膨胀变化率,提出径向吸湿膨胀系数β,模型,描绘复合材料的吸水率和尺寸稳定性的关联,并定量考察化学改性效果。结果表明：WPCs中入MGPPE后,相比同等木粉用量和等温环境的WF/HDPE,其水分扩散速率、平衡吸水率和扩散系数均有所降低,有助于降低复合材料的吸水程度,从而减少试样的吸湿膨胀,提高材料的尺寸稳定性,当MGPPE用量增加时更为明显。更多还原

【Abstract】 Wood plastic composites (WPCs) is cheap, easily molding and anticorrosion compared to normal wood, and is widely used in field of furniture and plates. However, WPCs with high filler loading has some problems about processing, molding and selecting compatibilizer.Maleic anhydride/cardanol glycidyl ether copolymers (MGPPE) was synthesized from glycidyl3-pentadecenyl phenyl ether (GPPE) and maleic anhydride (MAH) initiated by BPO. And then the MGPPE was applied as a reactive comparabilizer to prepare HDPE/WF composite. Meanwhile, composites with GPPE and common comparabilizer such as MAH-g-PE (MPE) and mealted petroleum resin (C5) were also prepared for comparison purpose.The conversion rate of MAH in MGPPE was indirectly determined by1H NMR. An orthogonal experiment was used to investigate the impact of each factor on the MAH reaction conversion rate. And the optimum reaction processing for the highest conversion rate of MAH and the sequence of every influence factor were obtained. Meanwhile, Fourier infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and1H NMR results suggest that graft copolymerization had taken place successfully. The inferring reaction mechanism and the structure of MGPPE were proposed. Thermal gravimetric analysis (TGA) domesticated that graft copolymerization of GPPE and MAH was favor for improving thermal stability.The mechanical properties of WPCs with different MGPPE loading was studied by FTIR, contact angle measurement and interface morphological analysis. Furthermore, the interfacial property of WPCs and the modified mechanism of MGPPE were investigated. Composites with GPPE and common compatibilizer were also prepared for evaluating the compatibility of MGPPE. The results showed that the mechanical property and interface compatibility of composite improved with the addition of MGPPE, which modified effect is equal to MPE and higher than MCs. When the loading of MGPPE was4wt%, the compatibility was optimum for WPCs which showed the best mechanical property.The viscoelastic property and processing performance were studied by plate rheomter and Huck rheomter. A small amplitude oscillation experiment was applied to determine the impact of different WF loading and different compatibilizer on rheological properties of interfacial adhesion of WPCs. Furthermore, carreau model was applied to investigate the effect of WF loading and compatibilizer types on Newtonian index and relaxation properties. The results showed that the relaxation time could reflect the relationship between multi-scale structure and structure of WPCs. MGPPE was compatible with HDPE. Composite filled with MGPPE showed similar rules of modulus varying with strain and frequency, as composite without MGPPE. The presence of MGPPE prolonged the stress relaxation time, which lead to increased long carrying capacity of composite samples.In addition, property of isothermal crystallization for HDPE in high filled WPCs was further studied by combining DSC and XRD. And the impact of WF loading, compatibilizer types and the network structure of wood flour particles on crystallization kinetics parameters and thermodynamic parameters of HDPE matrix were analyzed. The major factors affecting crystallization behavior and crystallization process of HDPE matrix were summarized. The results suggested that WF and compatibilizer had little effect on the crystallization behavior of HDPE, but influenced the grain size of HDPE during crystallization process. Composite with compatibilizer exhibited a higher Avrami index than the one without, which meant that compatibilizer could promote the perfection of crystal growth.Finally, the impact of WF loading, temperature and compatibilizer types on hygroscopic property of composite was studied. In terms of water transport dynamics, variation for water absorption, moisture diffusion rate and the diffusion coefficient of WPCs was discussed. Meanwhile the characteristics of diffusion activation energy of WPCs were investigated from the thermodynamic aspects of water transport. Furthermore by means of the examination of the swelling rate of the composite, a pr model was proposed, which depicted the association of the water absorption and dimensional stability of the composite, to investigate the chemical modification effect quantitatively. The results depicted that moisture diffusion rate, balance water absorption and diffusion coefficients of the composite with MGPPE lower than the composite without MGPPE in the same WF loading and temperature condition. It is concluded that MGPPE was helpful for reducing the moisture expansion of the sample and improved the dimensional stability of the composite. And the effect was significant when the MGPPE content was higher.更多还原