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

Abstract

A new method of toughening polymerized cyclic butylene terephthalate (pCBT) with tetrahydrofuran (THF) is proposed. The\ud pCBT was prepared by in situ ring-opening polymerization of a commercial cyclic butylene terephthalate, a cyclic form of\ud poly(butylene terephthalate), in the presence of THF. In comparison to conventionally polymerized pCBT, the resultant material\ud was found to be ductile, showing a strain at break of well above 100% in tensile tests. Other matrix properties, such as tensile\ud modulus, tensile strength and glass transition temperature, were not significantly altered by the addition of THF. It was found\ud that the presence of THF enhanced the polymerization reaction, resulting in an increased molecular weight and a narrowed\ud molecularweightdistribution. Moreover, remaining oligomers after polymerization were extractedby the THF anda toughened\ud oligomer-free pCBT was obtained. The influence of time and temperature on the long-time toughening action of THF was\ud studied. The results showed that samples became brittle after 3months when subjected to a temperature of 80 ◦C, resulting in\ud a reduction of the toughening action.\ud c 2010 Society of Chemical IndustryPeer ReviewedPostprint (published version

Simultaneous binding and toughening concept for textile reinforced pCBT composites: Manufacturing and flexural properties

“…However, the stiffness and strength were found to be decreased in these co-polyesters due to the properties of the co-polymers used. In the case of THF [33] and low molecular weight bi-functional epoxy resin [34], the resulted pCBT shows an increased ductility, with other important properties such as tensile strength, tensile modulus and glass transition temperature were not significantly altered. In a further attempt, physical modification was also done by adding carbon nanotubes (CNT) with content up to 0.1 wt.% [36].…”

“…Therefore, toughening of pCBT matrix has been attracted considerable attention, due to the increasing demand of high performance engineering thermoplastic composites [31][32][33][34][35][36]. There are usually two toughening approaches for pCBT matrix during isothermal production, including chemical modification by co-polymerization with soft polymers [32,34], organic solvent [33] and physical modification by addition of nanoparticles [36].…”

“…For co-polymerization of CBT with soft polymers, investigations have been performed with polycaprolactone [36], polytetrahydrofuran [36], poly(viny butyral) [37], e-caprolactone [38], poly[ethylene-co-(vinyl acetate)] [39], tetrahydrofuran (THF) [33] and low molecular weight bi-functional epoxy resin [34]. The resulting co-polyesters showed increased toughness in the case of polycaprolactone [36], e-caprolactone [38] and poly[ethylene-co-(vinyl acetate)] [39].…”

Isocyanate toughening of pCBT/organoclay nanocomposites with exfoliated structure and enhanced mechanical properties

“…THF may have partially remained in the CBT blends after solvent blending, which can be explained by the fact that its chemical structure is similar to the one of the diol-derived portion in pCBT. It was shown that THF can lead to a pCBT with increased ductility but decreased stiffness and strength [38]. Finally, the sample pCBT100/PMDI/Cl30B 96/1/3-MB showed a stiffness and strength increase of ca.…”

A Review of the Recent Advances in Cyclic Butylene Terephthalate Technology and its Composites

“…It has been reported that pCBT can be effectively toughened by the addition of tetrahydrofuran (THF) prior to polymerization. 91 The resultant pCBT was found to be tough, showing a strain at break of well above 100% in tensile tests.…”