To solve the problem of uncontrollable degradation cycle of polylactic acid(PLA)films,prepraed phosphotungstic acid/PLA composite photodegradable films with polylactic acid as substrate and phosphotungstic acid as photocatalyst by tape casting method.In which,phosphotungstic acid content was 0.1,0.2,0.3 and 0.4 g,respectively.The experimental results showed that the thermal stability of the phosphotungstic acid/PLA composite film increased with the increase of phosphotungstic acid content.The thermal decomposition temperature of the pure PLA film was 285.54 ℃.When the content of phosphotungstic acid was 0.1 g,the maximum thermal decomposition temperature of the composite film increased to 371.61℃;As the content of phosphotungstic acid increased,the degradation rate of phosphotungstic acid/PLA photocatalytic films accelerated.When the content of phosphotungstic acid increased to 0.3 g,the degradation rate was the highest,the weight loss rate reached 22.3％after 31 h of exposure to sunlight;SEM testing results showed that when the content of phosphotungstic acid was 0.1,0.2 and 0.3 g,phosphotungstic acid was evenly distributed in the PLA film and the film was dense;When the content of phosphotungstic acid was greater than 0.4 g,phosphotungstic acid aggregated in the film.By added free radical scavengers,it was shown that·O2-was the photocatalytic active center in the photodegradation process of phosphotungstic acid/PLA composite film.
维普
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