Fundació Privada ASCAMM, Parc Tecnològic del Vallès, Av. Universitat Autònoma 23, E-08290, Cerdanyola del Vallès Barcelona, Spain; Ultrasion S.L., Parc Tecnològic del Vallès, Av. Universitat Autònoma 23, E-08290, Cerdanyola del Vallès Barcelona, Spain.
Ultrason Sonochem. 2014 Jan;21(1):376-86. doi: 10.1016/j.ultsonch.2013.07.007. Epub 2013 Jul 25.
A new ultrasonic micro-molding system was used to process polylactide (PLA) and fabricate reduced dimension specimens. Plasticization and molding of PLA were achieved by applying ultrasonic waves after feeding the polymer into a plasticizing chamber. Chemical and physical characteristics of processed PLA varied depending on the processing window (i.e. changes in ultrasonic wave amplitude between 14.2 and 48.1 μm and molding pressure between 0.5 in 6 bars). In terms of chemical effects, the application of ultrasound can lead to lower molecular weights (e.g. decreases of more than 45% in the weight average molecular weight), revealing partial degradation of the material. Also, the processed materials exhibited slightly higher thermal degradability than pure PLA because ultrasonic vibrations break molecular linkages and worsen the polymer structure. Finally, the processing conditions for the preparation of PLA specimens could be optimized without causing degradation and preserving structural characteristics and mechanical properties. Specifically, the use of an amplitude of 48.1 μm and a pressure of 3 bars gave samples with the same molecular weight as the raw material (i.e. 117,500 g/mol as opposed to 117,300 g/mol for Mw).
采用新型超声微成型系统对聚乳酸（PLA）进行加工并制备缩尺试件。将聚合物送入塑化腔后施加超声波，实现 PLA 的塑化和成型。加工 PLA 的化学和物理特性取决于加工窗口（即超声波幅度在 14.2 和 48.1 μm 之间变化，成型压力在 0.5 到 6 巴之间变化）。就化学效应而言，超声的应用会导致分子量降低（例如重均分子量降低超过 45%），表明材料发生了部分降解。此外，由于超声振动会破坏分子键并恶化聚合物结构，因此加工材料的热降解性略高于纯 PLA。最后，可以在不引起降解且保持结构特性和机械性能的情况下优化制备 PLA 试件的加工条件。具体来说，使用 48.1 μm 的振幅和 3 巴的压力可获得与原材料相同分子量的样品（即 117,500 g/mol，而 Mw 为 117,300 g/mol）。
