可降解塑料在不同土壤填埋下热性能变化及碳元素组成分析

Changes of Thermal Properties and Carbon Composition of Biodegradable Plastics Under Different Soils Landfill

为探究可降解塑料聚乳酸(PLA)、聚对苯二甲酸-己二酸丁二醇酯(PBAT)及其共混塑料(PBAT/PLA)以及不可降解塑料聚乙烯(PE)在红壤、小粉土和青粉泥中的降解行为,采用失重分析、差示扫描量热仪(DSC)和元素分析-稳定同位素比率质谱仪(EA-IRMS)评估上述4种塑料在土壤填埋下的特征变化。结果表明,不同塑料在土壤中的降解性能存在差异。随着降解程度的增加,可降解塑料的玻璃化转变温度(T_(g))、冷结晶温度(T_(c))以及熔融温度(T_(m))向低温方向偏移,δ^(13)C值有升高的趋势,%C有降低的趋势。其中,PBAT/PLA在青粉泥中填埋180 d后的失重率最大,为95.1%,其T_(g)由61℃降至58℃,T_(c)由113℃降至104℃,δ^(13)C值从-24.1‰增加到-21.8‰,%C从54.9%降低至40.5%。表明DSC和EA-IEMS或可用于定性监测塑料在环境中的降解行为。本研究结果为可降解塑料在环境中的降解行为研究提供了新思路。

In order to investigate the degradation behavior of biodegradable plastics polylactic acid(PLA),polybutylene adipate-co-terephthalate(PBAT),blend plastic(PBAT/PLA)and non-degradable plastics polyethylene(PE)in red soil,small silt and green silt,the characteristics of the above four kinds of plastics in soil was evaluated by weight loss analysis,differential scanning calorimetry(DSC)and elemental analyzer-isotope ratio mass spectrometry(EA-IRMS).The results showed that the degradation performance of different plastics in soils was different.With the increase of degradation degree,the glass transition temperature(T_(g)),cold crystallization temperature(T_(c))and melting temperature(T_(m))of biodegradable plastics shifted to the low temperature direction,theδ^(13)C value increased and the%C decreased.Among them,the weight loss of PBAT/PLA after 180 days of landfill in green silt was the largest,95.1%,T_(g) decreased from 61℃to 58℃,T_(c) decreased from 113℃to 104℃,δ^(13)C value increased from-24.1‰to-21.8‰,%C decreased from 54.9%to 40.5%.DSC and EA-IEMS could be used to qualitatively monitor the degradation behavior of plastics in the environment.Results of this study provided a new way to study the degradation behavior of biodegradable plastics in the environment.