塑料瓶的主要材料一般是PP（聚丙烯）及少量的PET（聚对苯二甲酸乙二醇酯）。利用废旧塑料瓶为原料制作衣服需要经历一个复杂的物理化学过程。据中国科学院兰州分院化学物理研究所博士简令奇介绍，PET的回收分为物理回收和化学回收。物理回收是指用粉粹机或破碎机进行物理法切碎，把塑料瓶轧成细碎片，再通过加热熔化后去除杂质，再经过抽纱即可纺成线。化学分解是指废弃塑料的水解或醇解（乙醇解、甲醇解及乙二醇解等）过程，通过分解反应，可使塑料变成单体或低相对分子质量物质，可重新成为高分子合成的原料。化学分解产物均匀控制，不需进行分离和纯化，生产设备投资少。
【正确答案】：Plastic bottles are made chiefly from PP (polypropylene), with a small amount of PET (polyethylene glycol terephthalate). And the use of waste plastic bottles as textile material to make clothes is a complicated physical and chemical process. According to Dr. Jian Lingqi, a scientist from the Chemistry and Physics Research Institute, Lanzhou Branch of the Chinese Academy of Science, the reclamation of PET can be classified into two categories: physical and chemical. The former refers to the physical process of firstly breaking the bottles into fine scraps with a grinder or crusher, then melting the scraps to remove impurities, and lastly drawing yarn so as to spin knitting wool. The latter is called chemical decomposition, which refers to the hydrolysis or alcoholysis (ethyl, methyl or ether) process of waste plastics. By way of decomposition, plastics are made into monomers or substances with relatively low-molecular mass that can be turned back into high-molecular synthetic materials. The products of chemical decomposition are uniform and easily controlled, without any need of separation or purification. And, what’s more, the production equipment costs less.
