Synergistic effects of β‐cyclodextrin containing silicone oligomer on intumescent flame retardant polypropylene system

Abstract

AbstractThe effects of β‐cyclodextrin containing silicone oligomer(CDS), as a synergistic agent, on the flame retardancy and mechanical properties of intumescent flame retardant polypropylene composites were studied by adding different amounts of CDS in intumescent flame retardants. The limiting oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were utilized to evaluate the synergistic effects of CDS in the composites. It was found that after a little amount of CDS partially replaced a charring‐foaming agent (CFA) in IFR, LOI values of the composites were enhanced and they obtained a UL‐94 V‐0 rating. IFR system containing 6.25wt% CDS presented the best flame retardancy in PP. The experimental results obtained from LOI and UL‐94, TGA, SEM, and mechanical properties indicated that the combination of CDS and CFA presents synergistic effects in flame retardancy, char formation, and mechanical properties of the composites. This is probably due to different structures of polyhydroxyl macromolecules (CDS and CFA), the existence of dimethyl silicone group in CDS, and the toughness of epoxy silicon chain in CDS. SEM results proved that the interfacial compatibility between IFR and PP was improved by CDS. Copyright © 2009 John Wiley & Sons, Ltd.