改性介孔硅-ESO/聚丙烯三元体系复合材料增强增韧机制

以改性介孔硅为主要补强剂,聚丙烯(PP)为基体树脂,环氧大豆油(ESO)为增塑剂和稳定剂,通过熔融挤出注塑方法制备了改性介孔硅-ESO/PP体系复合材料。通过XRD、SEM、光学显微镜(OM)、偏光显微镜(PLM)及力学性能测试对介孔硅与ESO增强增韧PP的机制进行分析。结果表明:改性介孔硅、ESO二者同时填充PP制备改性介孔硅-ESO/PP复合材料时,三者界面以物理交联或化学接枝的结合方式形成了空间网状结构,改性介孔硅均匀分散在PP基体中;改性介孔硅添加量一定时,随ESO用量增加,改性介孔硅-ESO/PP复合材料弯曲强度稍微下降,但抗冲击强度、硬度都得到提高,当改性介孔硅用量为20%(与PP的质量比)、ESO用量为2.5%(与PP的质量比)时,综合性能较好。改性介孔硅本身的高模量及粒子在聚合物熔体中的异向成核促进了基体树脂结晶,以及良好的界面结合及分散性,这是增强的主要原因。ESO分子插入聚合物分子链间,削弱了聚合物分子链间的移动性,一定程度降低了基体结晶度等是增韧的主要原因。改性介孔硅使α晶型PP转变为具有更高冲击强度β晶型PP,与ESO二者协同作用,能增强增韧,但是过多的ESO使介孔硅粒子集中在材料的表面,导致其表面硬度增大。

Reinforcing and toughening mechanisms of modified diatomite-epoxy soybean oil/polypropylene composites

The modified diatomite was used as the main filler,polypropylene(PP) resin as the matrix,epoxidized soybean oil (ESO) as the plasticizer and heat stabilizer,the modified diatomite-ESO/PP composites were prepared by melting blending method.The factors of influence and strengthen toughening mechanism was analyzed by XRD,SEM,optical microscope (OM),polarizing microscope (PLM) and mechanical properties test.The results show the space grid structure of the modified diatomite-ESO/PP can be formed through the combination of physical crosslinking or chemical grafting among the interface of diatomite,ESO and PP,and diatomite can disperse in PP matrix uniformly.When modified diatomite mass ratio remains invariability,with the increase of ESO content,the flexural strength of the modified diatomite-ESO/PP decreases slightly,but the impact strength and hardness increase.With 20％ mass ratio to PP of modified diatomite and 2.5％ mass ratio to PP of ESO,the modified diatomite-ESO/PP composite with optimal mechanical properties can be obtained.The reinforcement of the modified diatomite-ESO/PP is mainly beacause that the modified diatomite has some characteristics such as a high modulus,the heterodromous nucleation in the polymer melt promoting the crystal of PP,a better interfacial adhesion with matrix,and a good dispersibility.ESO can insert into polymer molecular chains,weak the mobility among the polymer molecular chains,and to a certain extent reduce the crystallization of the matrix,which lead to improve the toughness of PP matrix.Due to the modified diatomite adding to the PP matrix,α crystal of PP transferms into β crystal of PP with higher impact strength,thus the modified diatomite and ESO can work cooperatively and achieve reinforcing and toughening of the modified diatomite-ESO/PP composite.However,more adding of ESO makes the modified diatomite focus on the surface of composites,and results in the increase of the surface hardness of the modified diatomite-ESO/PP composite.