Improvements on Flame Retardant Properties of PET/Montmorillonite Nanocomposite Caused by Polyborosiloxane
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1007-S12-33
Improvements on Flame Retardant Properties of PET/Montmorillonite Nanocomposite Caused by Polyborosiloxane Yue Huo1, Qinguo Fan1, Nicholas A Dembsey2, and Prabir K Patra1 1 Materials and Textiles, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA, 02747 2 Fire Protection Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, 01609-2280 ABSTRACT A phenyl-containing highly cross linked polyborosiloxane (PBSiO) was synthesized as a flame retardant for polyethylene terephthalate (PET). We coated montmorillonite (MMT) clay, a very high aspect ratio and high specific surface area layered silicate with synthesized PBSiO to introduce synergism in flame retardation to the PET nanocomposite film that retained thermal and mechanical properties. This PBSiO has high thermal stability at the processing temperature (270-285º C) of PET and acts as a compatibilizer between PET and clay that are otherwise incompatible. During burning, the flame retardant PET containing PBSiO and MMT forms a protective borosilicatecarbonaceous intumescent char on the surface. Cone calorimeter tests were performed to evaluate key fire properties of the PET/PBSiO/MMT. The peak heat release rate (PHRR) of PET that contains 5 wt% PBSiO and 2.5 wt% MMT was reduced by 60% and similar trend in the reduction of mass loss rate of the nanocomposite was observed. INTRODUCTION PET, as one of the most common thermoplastic polymer, has found wide applications in many fields such as engineering plastics and fibers because of its high performance, excellent dimensional stability, good thermal stability, good dyeability, chemical resistance, recycling ability and low cost. However, flame retardation of PET is demanded in many applications. Traditionally, PET is flame retarded with brominecontaining compounds, alone or coupled with antimony source [1]. The halogencontaining additives are very effective to reduce the fire risk but may produce large amounts of smoke and highly toxic and potentially carcinogenic halogenated furans and dioxins during burning and incineration [2]. Non-halogen phosphorus-based additive, surface finish or co reactant systems have been used for a long time in PET textiles [3]. However, the moisture absorption of phosphorus-based additive adversely affects the performance of PET on dimensional stability and the catalyzing action of phosphoric acids to PET deteriorates the thermal stabilities, these limit the applications of phosphorus-based flame retardant additives in PET to some extent. The demands on flame retardants for PET are stringent due to the high processing temperatures at 270285ºC and the need for long-term dimensional stability. Many additives tend to cause deterioration in the mechanical and thermal properties of the PET resin. Tensile elongation and notched impact (Izod) resistance are particularly sensitive to the amount, particle size, and dispersion of the additives in the resin. All these requirements have excluded most of the known commercially available
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