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Recent regulation IEC 60335-1 ed.4 (2008) was introduced for materials used in electric appliance, establishing new limits in Glow Wire Ignition Temperature (GWIT) performance for materials used for electric connectors. Development of new products with high GWIT is possible, but the main issue is to keep good mechanical properties and processability, as well as tracking resistance (Comparative Tracking Index-CTI). Only a few patents and scientific publications exist about glow wire test performance of polymers. In this work we report GWIT and CTI properties for three engineering thermoplastic polymers (PBT, PET and PC). We have also studied the phenomena involved in this test, treating the phenomena with the parameterisation approach already used in the studies of the fire behaviour of polymers. PC, PBT and PET filled with 30% w/w glass fibres have been tested, and material properties that can be related to GWIT and CTI performance have been measured by TGA, Laser Flash Thermal Diffusivity (LFTD), Pyrolysis-GC/MS. CTI seems to be correlated with the char formation tendency of the materials, so PBT show a higher tracking resistance than PET and PC. Polycarbonate was the only material that passed the glow wire test (GWIT higher than 775 °C) but generally GWIT performance is not directly related with degradation temperature, since PET is thermally more stable compared with PBT, but less stable in glow wire test. The ignition process, together with the unsteady heat and mass transfer process characteristic of glow wire testing, are affected by many parameters at the same time. That’s why it is not easy to relate results of TGA, Laser flash, Pyrolysis-GC/MS with the glow wire ignition temperature of the materials tested, but the whole of these properties can give useful indication.

Poly(butylene terephthalate) nanocomposites with organically modified montmorillonites have been prepared by in-situ ring opening polymerization of PBT cyclic oligomers. High molecular weight polymers can be obtained by choosing the proper polymerization conditions and catalyst in very short polymerization time (10 min) and low temperature (205°C). A better dispersion of the clay and a consistently higher Mw have been obtained by this method respect to the standard melt intercalation approach, leading to improved thermo-mechanical properties of the nanocomposite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A new method for the insertion of aliphatic moieties into bisphenol A (BPA) polycarbonate (PC) by reactive blending with ethylene carbonate (ETC) has been developed. By this route, new polymeric materials with modified thermal and rheological properties have been synthesized; the structure of the poly(ether-co-carbonate)s prepared can be controlled using different ETC/PC molar ratios. Using model compounds and selective degradation reactions, the different chemical structures of the aliphatic units inserted into PC backbone were identified. ETC/PC molar ratios below 1 afforded both aliphatic–aromatic carbonate and ether groups, while higher ETC/PC molar ratios afforded aliphatic–aromatic ether and aliphatic–aliphatic carbonate groups. The co-polymers prepared by the new process were clear without discoloration or opacity. The thermal analyses of the co-polymers showed that, by the insertion of aliphatic moieties, it is possible to modulate the glass transition temperature (Tg) in a 30°C range. A decreased melt viscosity of the co-polymers was also observed and therefore an improved processability should be expected with respect to standard PC. The reaction with aliphatic carbonates can be also considered as a promising chemical recycling process for PC scraps, through the synthesis of monomers such as bis(hydroxyethyl)ether of BPA. This monomer has already been used for the preparation of co-polyesters of terephthalic acid with high Tg and thermal stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39820.

Novel copolyesters have been prepared by melt mixing poly(ethylene terephthalate) (PET) with an ethoxylated bisphenol S, with the aim to prepare new polyesters with increased Tg, to be used in a wider range of temperatures with respect to neat PET. No side reactions occur during the synthesis of the samples, as proved by NMR analysis. The insertion of the bisphenol S (sulfonyldiphenol) groups does not significantly alter the thermal stability of PET. The thermal analysis showed that Tm and crystallization rate of the copolymers decreased with incasing co-unit content. The Tg of the copolyesters can be increased by bisphenol S insertion, up to 40°C higher with respect to neat PET, that allows the use of amorphous PET in a wider range of applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Telechelic poly(butylene terephthalate) (PBT) ionomers have been prepared by melt synthesis using a new polycondensation process that involves a pre-reaction of sulfobenzoic acid sodium salt with butanediol. No side reaction occurs and the incorporation of the ionic groups is quantitative. The addition of a buffer agent, such as Na 3 PO 4 , to the catalyst reduces the THF formation and improves the polycondensation rate. The comparison of the thermo-mechanical and physical properties between random and telechelic ionomers is also reported. The ionic groups act as chain-extension reversible electrostatic links for telechelic ionomers while act as cross-links in random ionomers. Therefore, random ionomers present a consistently higher melt viscosity compared to telechelic ionomers and to PBT and for this reason high molecular weight random ionomers cannot be obtained by melt polycondensation. Thermal and hydrolytic stabilities of telechelic ionomers are comparable with those of commercial PBT and consistently higher respect to those of random ionomers. The presence of ionic groups decreases the translation mobility of the polymer chains thus lowering the crystallization rate.

Telechelic ionomeric poly(butylene terephthalate) nanocomposites with organically modified clays have been prepared by the melt intercalation technique both in Brabender mixer and in twin screw-extruder. The presence of ionic groups tethered at the end of the polymer chains permits electrostatic interaction between the polymer and the surface of an organically modified clays providing a thermodynamic driving force for the dispersion of the clay platelets in the polymer matrix. The improved dispersion has been verified by TEM and XRD analyses. Nanocomposites with telechelic polymers present therefore consistently higher thermo-mechanical properties and improved thermal and hydrolytic stability respect to nanocomposites with standard PBT. Nanocomposite obtained using PBT with 3% telechelic ionic groups and with 5% of clay present a heat deflection temperature that is 48 °C higher compared to that of the commercial material. The presence of the clay also slightly increases the thermal and hydrolytic stability respect to standard PBT.

In this paper we present the main technologies developed over the last decades on chemical recycle of PET from a practical and economical point of view. We show details of plants used to carry out solvolitic reactions emphasising steps of purification, which are sometimes not considered when discussing chemical, recycle but which, in fact, are the key feasibility factors. The recycling or modification of PET to obtain monomers and other useful chemicals as intermediates and additives is carefully considered.

Les polythioesters obtenus par polycondensation interfaciale du 4,4'-dimercapto biphenyle avec les dichlorures de diacide ClCO-(CH 2 ) n -COCl (n=10, 10, 13) sont caracterises par FTIR RMN 1 H, GPC et DSC. Les 3 polymeres presentent 2 transitions thermiques, quasi-confondues pour n=13; la premiere transition de phase observee pour n=13 est la fusion; un liquide anisotrope dont la morphologie est caracteristique d'un cristal liquide nematique est obtenu