A polypropylene (PP) film photodegradation test was performed in water at 60 °C with a specific photocatalyst under visible light irradiation to identify its fragmentation mechanism. The photodegradation degree reached a maximum at the 144 h photodegradation time and showed the decreases at the 288 h. The surface being uneven was observed at the 288 h in the SEM photograph. These results showed that the surface exfoliation was provoked by the test. The spherulite structure contributed to the surface microcrack location and growth. The microcrack allowed entrance of water into the inner amorphous part. The water caused an internal stress by expanding itself due to radiant heat from the visible light irradiation and induced a microcraze in the interlamellar amorphous region. The microcraze developed into an internal microcrack, and surface microcracks finally coalesced together, producing a planar exfoliation. The major long side length of the exfoliation part was below 100 μm at both the 144 h and 288 h. The weight change ratio and rate of the photodegraded PP film showed multi-stages with the increase of photodegradation time. The increment of positive rate was small, showing that the exfoliation caused suppression of the autoxidation rate. The negative rate was due to the exfoliation behavior and was nonlinear to the photodegradation time.

在可见光照射下，使用特定的光催化剂在60°C的水中于水中进行聚丙烯（PP）膜的光降解测试，以确定其断裂机理。光降解度在144 h时达到最大值，而在288 h时下降。在SEM照片中在288小时观察到表面不平坦。这些结果表明该测试引起了表面剥落。球晶结构有助于表面微裂纹的定位和生长。微裂纹允许水进入内部非晶态部分。水由于来自可见光辐射的辐射热而自身膨胀，从而引起内部应力，并在层间非晶区域中引起微裂纹。微裂纹发展成内部微裂纹，最终，表面微裂纹合并在一起，产生平面剥落。在144h和288h处，剥落部分的主要长边长度均低于100μm。随着光降解时间的增加，光降解PP薄膜的重量变化率和速率呈现多阶段变化。阳性率的增加很小，表明脱落导致自氧化率的抑制。负速率归因于剥离行为，并且与光降解时间无关。表明剥落会抑制自氧化率。负速率归因于剥离行为，并且与光降解时间无关。表明剥落会抑制自氧化率。负速率归因于剥离行为，并且与光降解时间无关。