Alkaline‐solution‐induced crystallization in poly(butylene terephthalate)

Abstract

Subtle crystalline structure changes of poly(butylene terephthalate) (PBT) specimens treated with an alkali solution at room temperature were investigated with the grazing incidence X‐ray diffraction (GIXRD) analysis method. A new phenomenon was found: the aqueous alkali solution induced the crystallization of the PBT polymer. Under the GIXRD analysis condition of an incidence angle of 1°, the penetration depth of the X‐ray in PBT was less than 80 μm, and this agreed well with the rough theoretical estimation. The alkali solution adopted in this study was an aqueous sodium hydroxide solution, which had a concentration of 2.5 N. Dissolved quantities of the surface layers during the alkaline treatment were found to be small. No appreciable intrinsic viscosity change due to the alkaline treatment was detected. Possible factors that might contribute to the crystallization, such as water absorption and a chemical reagent effect, were examined, and a plausible explanation for the phenomenon was developed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1938–1948, 2004

Toughening of in situ polymerized cyclic butylene terephthalate by addition of tetrahydrofuran

“…The THF apparently acts like a nucleating agent, providing heterogeneous nucleation sites for the crystallization of the pCBT as well as increased chain mobility. Moreover, polyesters are known to undergo chemical‐induced crystallization 25–30. Therefore this increase in crystallinity is likely to be due to a solvent‐induced crystallization phenomenon.…”

Aminolysis of polyesters for cracking and structure clarifying: A review

“…Having polyester products brought into contact with liquid amines has to allow for the interaction of solvents on the increase of free volume and subsequent lowering glass‐transition temperature, its plasticizing effects, and inducing crystallization. The process of solvent‐induced crystallization of polyesters has been studied since 1949 43–56 . At first, it was found that several liquids initiate crystallization of PET at room temperature, well below the glass transition temperature 43 .…”

“…By exposure of PLA to 50% and 95% ethanol solutions α‐form crystals was detected 54 . Grazing incidence X‐ray diffraction analysis shows at room temperature an aqueous sodium hydroxide solution (2.5 N) induces crystallization on the surface layers of PBT polymer film 55 …”

“…PBT is commercially produced by the reaction of an aliphatic glycol (diol) with an aromatic di‐ester or diacid in the presence of a polyesterification catalyst, which is like the production of PET. The resins have advantages to be used in injection moldings 10,55,84,154 …”

“…The process of solvent-induced crystallization of polyesters has been studied since 1949. [43][44][45][46][47][48][49][50][51][52][53][54][55][56] At first, it was found that several liquids initiate crystallization of PET at room temperature, well below the glass transition temperature. 43 The rate of development of crystallinity varies markedly with the liquid used.…”