Aminolysis of polyesters for cracking and structure clarifying: A review

Abstract

Cracking of polyester bottles and recycling the waste, which is of concern in the current research works have their roots in the environmental stress cracking and the physical structural analysis, which has been the subject of a huge number of research reports, that are collected in the present review. Polyesters are polymers of high importance in industry and academia, and amines are versatile chemicals that are used for different purposes. The reaction of polyester with amines has been used to reveal structure, improve the properties of products, convert polyesters waste into benign materials, enhance biocompatibility, and so on. The research works reported on the aminolysis of polyesters (PET, PCL, PLA, PTT, PBT, PHB, PEN, PEA) for structure and morphological determination, etching, and stress cracking are critically reviewed. The chemistry and mechanism of the reactions of aminolysis of an ester or a polyester are well documented, and a vast amount of useful information is available. There is a need for further research to answer the remaining questions on the intermediates. Solutions of amines act as environmental stress‐cracking agents, may induce crystallization, and probably it can dissolve and remove a certain amount of disordered regions as well. In the subject of stress cracking that can help the elucidation of the process of aging, it is not yet clear how cracks patterns and sizes (from nano up to micro size) observed on the surface of polyester products depend on the thermal and mechanical history of the samples, and it is not known how to produce cracked patterns according to a pre‐planned design on the surfaces of polyester articles. To make polyesters more useful and safe the structure must be revealed in order to get benefit from the structure–property relations.

Modification of poly(ethylene terephthalate) fibers, fabrics, and films by amination reactions—A review

“…13,14 The evolution of the physical structure of PET, clarified by aminolysis, has been reviewed recently. 17 There are several occasions when PET copolymers, often less than 5 mol%, are produced and used for different applications. The introduction of monomers, adipate, and poly(ethylene glycol) (PEG) improves dyeability, and copolymerization of sodium 5-sulfoisophthalate can bind cationic dyestuffs.…”

“…27 Clarification of the physical structure of PET by aminolysis was described by a number of authors and was reviewed in another publication. 17 The products of the reaction of PET fibers with hydrazine, benzylamine, ethylenediamine, hexamethylenediamine, piperidine, and aniline were determined. Amides of terephthalic acid and oligomeric diamine were obtained.…”

“…The process of stress-cracking, which may be related to the shape and the physical structure has been reviewed recently. 17 The subject of the present review is limited to the fabrics, fibers, and films. The properties of fabrics depend on the properties of fibers.…”

“…Being partly crystalline, different models have been proposed for the physical structure of PET products, including the two‐phase fringed micelle, and the three‐phase model, with characteristic dimensions of microfibrils, the extent of chain folding, crystalline, and related orientation index that are the results of several research works 13,14 . The evolution of the physical structure of PET, clarified by aminolysis, has been reviewed recently 17 …”

Catalytic Steam-Assisted Pyrolysis of PET for the Upgrading of TPA

“…In contrast to the unsustainability of thermoplasticity, degradation is a reliable way to achieve the closed-loop recycling of waste PET. There are many studies on the degradation of PET, including bioremediation [ 7 , 8 ], glycolysis [ 9 , 10 ], aminolysis [ 11 , 12 ], and hydrolysis [ 13 , 14 ]. However, with these degradation methods, issues regarding product quality or production costs cannot be effectively addressed, which makes them difficult to be scaled up.…”