聚合物共混物的回收

Recycling of Polymer Blends

过去几十年内,对具有定制性能的多功能材料不断增长的需求促成了全新商用聚合物共混物的开发。它们相对于传统基体而言具有优异的物理性能,而且在新型塑料合成方面表现出经济优势。由于塑料废物治理方面的环境问题逐渐增多,分选技术中存在难题,而且绝大部分成对聚合物之间的化学相容性有限,因此聚合物共混物在回收方面的技术潜力往往没有得到挖掘。在某些情形下,在回收共混物中添加增容剂也无法令人满意地保持和/或定制其性能。该综述的目的是对聚合物共混物回收的可能性进行批判性分析。在关于塑料回收问题和定义的前导章节之后,介绍了关于聚合物共混物物理特性的一些基本概念。该综述第三章重点分析了聚合物共混物的机械回收方法,以及运用于相容和不相容聚合物共混物的回收方法之间的总体区别。这一章还分析了源于未分类废物的掺合塑料的回收潜力,以及再次热处理对聚合物共混物形态和热力学性能的影响。考虑到生物塑料在现代社会中与日俱增的重要性,该综述第四章主要介绍了含有生物塑料的共混物的机械和化学回收,尤其关注基于聚乳酸(PLA)和热塑性淀粉(TPS)的共混物。运用于聚合物共混物的回收技术的关键方面和未来展望将在该综述最后一章总结。

The growing need of multifunctional materials with tailor made properties led in the last decades to the development of novel commercial polymer blends,possessing superior physical properties with respect to traditional matrices and showing economical advantages with respect to the synthesis of new plastics.Due to the progressive increase of the environmental concerns on the management of plastic wastes,the difficulties in the sorting technologies and the limited chemical compatibility between the greatest part of polymer pairs,the technical potential of polymer blends often remains unexploited when the recycling stage is considered.In some cases,also the addition of compatibilizers to recycled blends does not represent a satisfactory solution to retain and/or tailor their properties.The aim of this review is that to perform a critical analysis of the potentialities of polymer blends recycling.After an introductive section on the problems and the definitions of plastics recycling,some basic concepts about the physical behaviour of polymer blends are reported.The third section of the review is focused on the analysis of the mechanical recycling of polymer blends,and a general distinction between recycling techniques applied to compatible and un-compatible polymer blends is performed.In this chapter,also the analysis of the recycling potential of commingled plastics deriving from unsorted wastes and of the effect of the thermal reprocessing on the morphological and thermo-mechanical behaviour of polymer blends is reported.Considering the increasing importance of bioplastics in the modern society,the fourth chapter of this review is focused on the mechanical and chemical recycling of blends containing bioplastics,with particular attention to polylactic acid(PLA)and thermoplastic starch(TPS)based blends.The key aspects of the recycling technologies applied to polymer blends and the future perspectives are summarized in the last section of the review.