The article experimentally investigates the interface strength of glass fibers in polypropylene (PP) with two different levels of crystallinity. The different degrees of crystallinity, 46.6% and 52.5%, were achieved using fast (quenching, ~4500°C/min) and slow (~2°C/min) cooling, respectively, during production of the PP film. The degree of crystallinity was measured using the differential scanning calorimetry. The mechanical properties of the films were characterized with the dynamic mechanical analysis and with a tensile test on Deben micro‐tester. Interfacial shear strength (IFSS) of glass fiber/PP was determined using fiber fragmentation test. Interfacial normal strength (IFNS) was determined using inverse identification based on finite‐element modeling of transverse tensile loading of a single fiber (Deben micro‐tester with digital image correlation‐based observation of the debonding). The measurements have confirmed the expected trend in mechanical properties of the film: increase of the storage and Young's moduli (room temperature) with the increase of degree of crystallinity, accompanied by the decrease in the loss modulus and tan δ. Interfacial strength followed the trend of the PP stiffness: both the IFSS and IFNS values for the PP with high crystallinity (slow cooling) are three (IFSS) and four (IFNS) times higher than those for the low crystallinity (fast cooling) case.

中文翻译：

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聚丙烯中玻璃纤维的界面强度：取决于冷却速率和结晶度

该文章通过实验研究了两种不同结晶度的聚丙烯（PP）中玻璃纤维的界面强度。在PP膜的生产过程中，分别使用快速（淬火，〜4500°C / min）和慢速（〜2°C / min）冷却，分别获得了46.6％和52.5％的不同结晶度。使用差示扫描量热法测量结晶度。通过动态力学分析和在Deben微型测试仪上的拉伸测试来表征薄膜的力学性能。玻璃纤维/ PP的界面剪切强度（IFSS）使用纤维断裂试验测定。界面法向强度（IFNS）是通过基于单根纤维横向拉伸载荷的有限元建模（基于数字图像相关性观察的Deben微型测试仪，基于剥离的观察）的逆向识别确定的。这些测量已经证实了薄膜机械性能的预期趋势：随着结晶度的增加，储能和杨氏模量（室温）的增加，同时损耗模量和tanδ的降低。界面强度遵循PP刚度的趋势：高结晶度（缓慢冷却）的PP的IFSS和IFNS值分别比低结晶度（快速冷却）的IFSS和IFNS值高三倍（IFSS）和四倍（IFNS）。这些测量已经证实了薄膜机械性能的预期趋势：随着结晶度的增加，储能和杨氏模量（室温）的增加，同时损耗模量和tanδ的降低。界面强度遵循PP刚度的趋势：高结晶度（缓慢冷却）的PP的IFSS和IFNS值分别比低结晶度（快速冷却）的IFSS和IFNS值高三倍（IFSS）和四倍（IFNS）。这些测量已经证实了薄膜机械性能的预期趋势：随着结晶度的增加，储能和杨氏模量（室温）的增加，同时损耗模量和tanδ的降低。界面强度遵循PP刚度的趋势：高结晶度（缓慢冷却）的PP的IFSS和IFNS值分别比低结晶度（快速冷却）的IFSS和IFNS值高三倍（IFSS）和四倍（IFNS）。