Poly(Ethylene Vinyl Acetate) (EVA)/Low Density Polyethylene (LDPE)/Ammonium Polyphosphate (APP) Composites Cross-linked by Dicumyl Peroxide for Wire and Cable Applications

Abstract

Formulations of chemically cross-linked poly(ethylene vinyl acetate) (EVA) and low density polyethylene (LDPE) blends containing intumescent flame retardant such as ammonium polyphosphate (APP) were prepared. Influence of polyethylene grafted with maleic anhydride (PEgMA), boric acid or combinations of them as well as various EVA/LDPE ratios on flammability, mechanical, thermal and electrical properties was investigated. Flame retardancy was found to be improved after addition of boric acid to APP formulations. On the other hand, mechanical properties decreased for formulations containing boric acid. Combination of boric acid with PEgMA gives formulations with good mechanical and thermal properties as well as good flame retardancy. Good thermal properties based on retention of mechanical properties after thermal aging were observed for all formulations due to introduction of cross-linking. All formulations show also good electrical properties.KEY WORDS: Mechanical Properties / Flame Retardance / Ammonium Polyphosphate / Talc / Crosslinking / Polyolefins due to their good mechanical properties, good resistance to chemicals and easy processing is used in many applications. However, they have some disadvantages such as low melting temperature, low thermal stability, high flammability as well as poor compatibility with additives. Compatibility of additives with polyolefins can be improved by addition of some compatibilizers or coupling agents.1 Thermal properties of polyolefins can be improved by small addition of stabilizers. A small quantity of processing stabilizers is usually added to prevent oxidative degradation of polyolefins caused by combined action of shear, heat and oxygen during their melt processing. Phenolic antioxidants are widely used as processing stabilizers for polyolefins.2,3 They act as scavengers of oxygen-centered alkoxy and peroxy radicals, but they are not able to provide long term heat stability. 4 The flame retardancy of polyolefins on the other hand can be improved using flame retardants. There are several types of flame retardants which are used to improve flame retardancy of polyolefins. Recently, there is a trend to avoid use of halogenated flame retardants due to environmental and safety concerns. Thus, as main non-halogenated flame retardants, mainly metal hydroxides 1,5-8 or intumescent flame retardant (IFR) systems 9-16 are used. Very good efficiency in flame retardancy of polyolefins can be achieved using IFR systems. However a higher loading of IFR additive is needed than that of some halogen-containing flame retardants. This results in lowered mechanical properties of the flame-retardant materials. Thus, the flame retardant efficiency of IFR should be further improved. To improve the performance of IFR in polyolefins, synergistic agents such as boroxo siloxanes (products of reaction of poly siloxanes with boric acid), 9,10 clays and nanoclays 13,14 or some metal-containing compouds 15,16 which can enhance the flame-retardant action of IFR can be used.In recent work, 17 current a...

The Thermal and Mechanical Properties of Poly(ethylene-co-vinyl acetate) Random Copolymers (PEVA) and its Covalently Crosslinked Analogues (cPEVA)

“…Yao et al [18] have also suggested that the thermal stability can be enhanced considerable by the crosslinking of PEVA. Crosslinked PEVA materials have been used for various fields such as photovoltaic modules, insulation materials, cables, damping mattress for railroad crossties, and shoe soles [26,27,28,29,30,31]. To improve its mechanical strength and thermal resistance properties, PEVA is generally cured by peroxide [32,33,34,35], such as dicumyl peroxide (DCP).…”

Development and characterization of new XLPE compounds for high performance cables in the automotive industry

“…The flammability of all the prepared formulations was tested by LOI. This test is widely used to evaluate flame retardancy of materials, especially for screening flame retarded formulations of polymers [2].…”

“…Regarding the enhancement of the mechanical performance of the system, that can be assured by blends of EVA/LDPE, as referred by Mosnacek et al, [2]. In this case, formulations of chemically crosslinked ethylene vinyl acetate (EVA) and low-density polyethylene (LDPE) blends were prepared.…”

Kinetic Study on Surface Modification of Ammonium Polyphosphate with Melamine

“…Ammonium polyphosphate (APP) and melamine (MEL) are typical components of intumescent halogen-free flame retardants. APP-based intumescent halogen-free flame retardants have been widely used in coatings (unsaturated polyester/epoxy resin, acrylate resin , ), fibers [polypropylene (PP) , ], plastics [PP, − polyethylene (PE), , polyurethane (PU), , polystyrene (PS), , epoxy resin (EP), , acrylonitrile–butadiene–styrene (ABS), , poly(butylene succinate) (PBS), poly(butylene terephthalate) (PBT), polyamide, styrene–acrylonitrile copolymer (SAN), biodegradable poly(vinyl alcohol) (PVA)/glycerol–plasticized thermoplastic starch (TPS), poly(lactic acid)/starch (PLA/starch)], and elastomers [styrene butadiene rubber (SBR), ethylene–propylene–diene terpolymer (EPDM)].…”