Sequential reordering in condensation copolymers, 2. Melting‐ and crystallization‐induced sequential reordering in miscible poly(butylene terephthalate)/polyarylate blends

Abstract

A 50/50 (weight ratio (38/62 mole ratio referred to repeating units)) blend of poly(butylene terephthalate) (PBT) and polyarylate (PAr), was studied by means of thermal, solubility, X-ray and nuclear magnetic resonance techniques after annealing procedures that enable transesterification. Prolonged thermal treatment at 290 "C gives rise to a copolymer that no longer reveals melting or crystallization. In accordance with previous reports, this effect is attributed to the formation of a random copolymer. Additional annealing of such samples at the relatively low temperature of 140°C results in the reappearance of melting endotherms in the differential scanning calorimetry curves. This effect is explained by crystallization-induced sequential reordering from random to block copolymer by means of transreactions. In that way a PBTPAr blend was shown to be another polymer system, along with poly(ethy1ene terephthalate) (PET)/polycarbonate (PC) and PETPAr blends, in which the entire cycle is realized, from two homopolymers via a block-and random copolymer to a block copolymer. The unusually low temperature at which the crystallization-induced sequential reordering to block polymers takes place is explained by the miscibility of PBT and PAr which enables transreactions to take place in the bulk.

Sequential Reordering in Condensation Copolymers, 6. Average Block Lengths in Poly(ethylene terephthalate) - Polyamide 6 Copolymers As Revealed by NMR Spectroscopy

“…[2,3,5,6,10] Blends of two or more different polyamides [8,11,12] or polyesters [7,9,13] have also been investigated. As yet, the polyamide-polyester blends have been Full Paper: An equimolar physical blend comprising poly(ethylene terephthalate) (PET), polyamide 6 (PA6) and catalytic amounts of p-toluene sulfonic acid (pTSA) was studied by differential scanning calorimetry (DSC) and 13 C NMR spectroscopy before and after reactive blending for various times at 280 8C that enables interchange reactions.…”

Sequence length determination in poly(ethylene terephthalate)-bisphenol-A polycarbonate random copolymers by application of selective degradation

“…1), the sample still displays some crysa T g being significantly higher than that of a similar copolymer obtained by simple annealing of a tallinity that completely disappears after 180 min annealing time (Fig. 1, curve d 4 2, curve b). The effect of the effective mixing upon the formation of amorphous PET-PC copolymers were introduced into the mechanical blend (the respective curve is not displayed).…”

“…3,4 Another important observation is ymer obtained by annealing of an equimolar mechanical blend directly in the DSC apparatus. 3 that the DSC traces of a PET-PC amorphous copolymer prepared by melt mixing at 280ЊC reveal After 45 min of such annealing at 280ЊC (curve c in Fig.…”

“…In some of these blends, transreactions can easily proven in numerous homopolymer blends. [3][4][5][6][7][8] Inrole of effective mass transfer in the molten homopolymer blend for the obtaining of amorphous cotensive research in this area has shown that the control of transreactions can provide a new polymers with a more or less random sequence distribution. method for preparation of copolymers within the processing equipment.…”

“…In lation of the lengths of the PET sequences based on NMR data, and size exclusion chromatography some samples, 0.5% by weight (based on both blend components) of tetrabutyl titanate [Ti-(SEC) of the selectively degraded PET-PC copolymer. By means of polarizing light microscopy (OBu) 4 ] were introduced as a transesterification catalyst, leaving out of account the trace amounts (PLM) an attempt is also made to evaluate the 5118 / 8E2B$$5118 02-06-98 07:39:02 polaas W: Poly Applied of the PET polymerization catalytic system possibly contained in this homopolymer that also promotes transesterification. Samples were taken from the reaction mixture at different stages of copolymer formation and further subjected to DSC.…”