Thermal behavior and crystallization kinetics of random poly(ethylene‐Co‐2,2‐Bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) copolyesters

Abstract

The thermal behavior of poly(ethylene-co-2,2-bis[4-(ethylenoxy)-1,4-phenylene]propane terephthalate) (PET/BHEEBT) copolymers was investigated by thermogravimetric analysis and differential scanning calorimetry. A good thermal stability was found for all the samples. The thermal analysis carried out using DSC technique showed that the T m of the copolymers decreased with increasing BHEEBT unit content, differently from T g , which on the contrary increased. Wide-angle X-ray diffraction measurements permitted identifying the kind of crystalline structure of PET in all the semicrystalline samples. The multiple endotherms similar to PET were also evidenced in the PET/BHEEBT samples, due to melting and recrystallization processes. By applying the Hoffman-Weeks' method, the T m 8 of PET and its copolymers was derived. The isothermal crystallization kinetics was analyzed according to Avrami's treatment and values of the exponent n close to 3 were obtained, independently of T c and composition. Moreover, the introduction of BHEEBT units was found to decrease PET crystallization rate. Lastly, the presence of a crystal-amorphous interphase was evidenced.

Poly(propylene isophthalate), poly(propylene succinate), and their random copolymers: Synthesis and thermal properties

“…Less attention has been paid to random copolymeric systems based on semicrystalline polyesters to clarify if and how the noncrystallizable comonomeric unit affects the formation and the amount of interphase. Several reports published by some of us demonstrated that the presence of the counits causes an increment of the interphase fraction 19–22. This result was explained on the basis of the formation in the copolymers of small and imperfect crystallites, which gives rise to a very dispersed crystalline phase with high crystal surface, exerting more extensive constraints on the amorphous phase.…”

Poly(ethylene terephthalate), modified with bisphenol S units, with increased glass transition temperature

“…For this reason, BPA has to be modified in order to be inserted in the polyester backbone during a standard polycondensation process 1. We have reported14–17 that the insertion of BPA units inside a terephthalate polyester can be achieved by derivatization of BPA via ethoxylation and the functionalized BPA was used directly in melt mixing with terephthalate polyesters. Bis(hydroxyethyl ether) of bisphenol A (BHEEB), can be prepared by several routes,18–22 such as for example by reaction between ethylene carbonate (ETC) and BPA.…”

Poly(propylene terephthalate) Modified with 2,2‐Bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) Units: Thermal Behaviour, Crystallisation Kinetics and Morphology

“…It must be stressed that the PBT/BHEEBT and PET/BHEEBT copolymers previously investigated showed a different behaviour, the thermal stability of PBT or PET being improved by the introduction of a minor amount of 2,2-bis[4-(ethylenoxy)-1,4-phenylene]propane terephthalate comonomeric units in the polymeric chain. [20,21] In order to investigate this trend more deeply, further experiments are currently being carried out and the results will be reported elsewhere.…”

“…[19] The thermal properties and crystallisation kinetics of PET/ BHEEBT and PBT/BHEEBT were previously investigated, paying attention to the effects of introducing the BHEEBT comonomeric units to the RAP fraction present both in PET and PBT. [20,21] The aim of this paper is to establish, for the PPT/ BHEEBT copolymeric system, any correlation between the thermal properties and kinetic parameters, as characterised by calorimetric and optical microscopy techniques, and copolymer composition, as determined by 1 H NMR spectroscopy. Moreover, attention has been paid to the effects which the introduction of the BHEEBT comonomeric units have on the PPT rigid-amorphous fraction.…”