Interfacial adhesion and the potential degradation are critical to service life and performances of plant fiber polymer composites. In this paper, the interfacial ultraviolet (UV) aging was studied by silane modification of hemp fiber on UV aging of the reinforced polypropylene (PP) composites. Three silane agents of 3‐(Trimethoxysilyl)propyl methacrylate (MPS), N‐[3‐(Trimethoxysilyl)propyl]aniline (PAPS), and (3‐Aminopropyl)‐triethoxysilane (APS) were selected to obtain different interfacial adhesion. The composite degradation was characterized by surface observations, surface degradations, and tensile tests. The results show that functional group of silane agent has considerable effects on UV aging of the polymer composites. For APS, the composites have higher interfacial adhesion and exhibit slower surface whitening, cracking, degradation, and less mechanical properties deteriorations than others. After 8 weeks aging, its fracture stress and fracture strain decreased of 5.3% and 8.0%, respectively. Because aniline of PAPS is incompatible with PP matrix, the composites have a relative weak interfacial adhesion and shows faster surface whitening, cracking, and degradation. While aniline absorbs UV radiation strongly and may retard the interfacial degradation, thus its fracture stress hardly decreased after 8 weeks. However, ester group in MPS absorbs UV radiation and may get degraded leading to the decline of interfacial chain slips. Thus, fracture strains of the composites decrease greatest of 35.2%. It is concluded that interfacial adhesion and potential degradation are critical in UV aging. A “suitable” modifier improves not only initial mechanical properties but also the weathering resistance of plant fiber polymer composites.

中文翻译：

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大麻纤维增强聚丙烯复合材料的硅烷改性和界面紫外线老化研究

界面粘合和潜在的降解对于植物纤维聚合物复合材料的使用寿命和性能至关重要。本文研究了大麻纤维的硅烷改性对增强聚丙烯（PP）复合材料的紫外线老化的影响，研究了界面紫外线（UV）的老化情况。选择了三种甲基丙烯酸3-（三甲氧基甲硅烷基）丙酯（MPS），N- [3-（三甲氧基甲硅烷基）丙基]苯胺（PAPS）和（3-氨基丙基）-三乙氧基硅烷（APS）的硅烷试剂以获得不同的界面粘合力。通过表面观察，表面降解和拉伸试验来表征复合材料的降解。结果表明，硅烷试剂的官能团对聚合物复合材料的紫外线老化具有相当大的影响。对于APS，复合材料具有较高的界面粘合力，并且表面变白，开裂，降解，并且机械性能的劣化比其他的要少。老化8周后，其断裂应力和断裂应变分别降低了5.3％和8.0％。由于PAPS的苯胺与PP基体不相容，因此复合材料的界面附着力相对较弱，并且表面增白，开裂和降解的速度更快。苯胺会强烈吸收紫外线并可能延迟界面降解，因此其断裂应力在8周后几乎不会降低。但是，MPS中的酯基会吸收UV辐射，并可能降解，从而导致界面滑移率下降。因此，复合材料的断裂应变最大降低了35.2％。结论是，界面粘合和潜在的降解对于紫外线老化至关重要。