Process for producing polyesters of multiple molecular weights

In one aspect, a method of reducing the molecular weight of a polyester includes mixing a composition comprising a polyester oligomer and a polyester in a molten state to form a modified polyester; wherein the mixing is carried out at a temperature of 230 to 330 DEG C; wherein the polyester oligomer is present in an amount of 0.1 to 50 wt% based on the total weight of the composition; wherein the polyester comprises a C2-12 alkyl phthalate polyester having a weight average molecular weight Mwi of from 15,000 to 100,000 g/mol as determined based on a polystyrene standard using gel permeation chromatography; and wherein the modified polyester has a weight average molecular weight Mwf that is at least 5% lower than the weight average molecular weight of the polyester. 在一个方面中，降低聚酯的分子量的方法包括混合包含聚酯低聚物和处于熔融态的聚酯的组合物以形成改性聚酯；其中混合在230至330℃的温度进行；其中聚酯低聚物以基于组合物总重量的0.1至50重量％的量存在；其中聚酯包含使用凝胶渗透色谱基于聚苯乙烯标准品测定的重均分子量Mwi为15,000至100,000g/mol的邻苯二甲酸C2-12烷基酯聚酯；和其中改性聚酯的重均分子量Mwf比聚酯的重均分子量低至少5％。