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通过对力学性能、红外光谱、粘均分子量及扫描电镜的分析,研究了煤/聚乙烯塑料在室内加速老化实验中的降解性能,并运用降解机理对实验过程进行解析及验证。结果表明,煤降解剂引发的交联和降解反应控制了薄膜的强度,使其柔韧性一直降低,且在整个120h光照过程中,断裂伸长率一直呈下降趋势;72h前是聚合物的氧化诱导期及衰变期,之后进入完全降解期。煤在改性塑料光照过程中引发自由基反应,引入羰基,导致聚乙烯大分子断链降解;共聚物的粘均分子量整体呈降低趋势,说明光照促进聚合物的降解,降解和交联交替控制着反应。煤/聚乙烯的光降解过程遵循链引发、链增长、链终止反应机理,在煤大分子光催化作用下,改变了聚乙烯常规光降解过程,加速了聚乙烯大分子断链和分子量降低。运用煤/聚乙烯塑料降解机理,能够解释样品力学性能变化、化学结构中羰基指数变化、分子量降低及降解过程中的现象和规律。
Through the analysis of mechanical properties, infrared spectra, viscosity average molecular weight and scanning electron microscopy, the degradation performance of coal / polyethylene plastic in accelerated aging experiment was studied, and the degradation mechanism was used to analyze and verify the experimental process. The results showed that the crosslinking and degradation reaction induced by the coal degrading agent controlled the strength of the film and decreased the flexibility of the film all the time, and the elongation at break showed a downward trend during the whole 120 h light irradiation. Induction and decay period, then enter the complete degradation period. Coal in the modified plastic light induced by free radical reaction, the introduction of carbonyl, polyethylene macromolecules led to chain scission; viscosity average molecular weight of the copolymer overall showed a downward trend, indicating that light to promote the degradation of polymers, degradation and cross-linked alternating control Reaction. The photodegradation of coal / polyethylene follows the mechanism of chain initiation, chain growth and chain termination. Under the photocatalysis of coal macromolecule, the conventional photodegradation process of polyethylene is changed and the chain scission and molecular weight of polyethylene macromolecule are accelerated. The use of coal / polyethylene plastic degradation mechanism can explain changes in the mechanical properties of samples, changes in the carbonyl index of the chemical structure, molecular weight reduction and degradation phenomena and laws.