Chemical and morphological alterations effected by methylamine reactions on polyesters

Abstract

Etching agents, including methylamine (MA) and several others, are used in many studies for exposing the crystal assembly in contrast to amorphous domains in polymer samples, for better morphology contrast. The selection of etching agents must be careful, so as not to alter the original chemical and crystal nature; otherwise misinterpretation may be a consequence. Apparently, the MA-vapor treatment does not simply just induce physical etching through peeling off a covered layer from the polymer samples as many investigators so believed, but also causes severe chemical changes in many aliphatic and aromatic polymers. The chemical reactions between MA and the polyesters ultimately lead to different chemical structures, alteration in spherulites and lamellae, and sometimes completely different lamellar structures with a different melting peak, with -C(=O)O- in the polymers being replaced with -C(=O)NH- bonding. This study uses three examples of polyesters to amply exemplify the necessity of due care in avoiding chemical etching. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.