The Retardant Properties Of Novel Intumescent Flame Retardant Low-density Polyethylene (LDPE) Composites

Low-density polyethylene (LDPE) has problem of poor water resistance and easily flammable, so it is necessary to improve the flame retardancy and poor water resistance.This paper researchs the synergistic effect between CFA and Si-APP and the intumescent flame retardant system mechanism. We have also prepared some semi-biodegradable flame retardant LDPE composites. The main research works are as follows:1. In order to overcome the poor water resistant property of traditional intumescent flame retardant meterial, we develop a new water resistant halogen free intumescent flame retardant LDPE composite which combine macromolecule into carbon technology and microencapsulated technology that based on a novel char forming agent (CFA) while dehydration agent and foaming agent choose silical gel parcel ammonium polyphosphate (Si-APP). The new LDPE composite not only has high thermal stability and flame retardant property but also overcome the difficulty of poor water resistance. In this work, we have summarized the flame retardant, mechanical and thermal properties, warter resistance ability of a novel intumescent flame retardant low-density-polyethylene (LDPE) composites, then found out the best flame retardant system. The tests results that only CFA and Si-APP are mixed at a suitable ratio, the coherent and dense char layer can be formed.When the mass ratio of CFA to Si-APP is1:3, The LOI value of LDPE/CFA/Si-APP reaches to the maximum29, which raise67.63percent compared with pure LDPE, while the maximum heat release rate decreased from1479.6kw/m2to273.5kw/m2and total heat release decreased from108.0MJ/m2to80.5MJ/m2, at the same time the LDPE composite has excellent water resistance property, which after168h the sample can still obtain a UL-94V-0.In the other hand, we also make the contrast experiment in order to certify the advantage of the above flame retardant system.we use Microencapsulated ammonium polyphosphate takes the place of silical gel microencapsulated APP (Si-APP). A novel intumescent flame retardant low-density polyethylene (LDPE) composites are formed by Microencapsulated ammonium polyphosphate(MCAPP) and a char forming agent (CFA), then studied the thermal, flame retardant, mechanical properties and hydrolytic resistance of low-density polyethylene (LDPE) by the influence of the intumescent flame retardant. The maximum of LOI value of LDPE composites is27. As a result, silical-gel microencapsulated APP (Si-APP) has a better advantage.2. In the second part we have perpared some semi-biodegradable flame retardant LDPE composites with melted blend method, in which the bamboo fiber is not only play a role in degradation, but also acts as a carbon source, while Si-APP acts as acid and air source. Through the limited oxygen index (LOI), UL94test and cone calorimeter test, we have investigated the flame retardant properties of the flame retardant LDPE/CFA/Si-APP composites. The results show that flame retardant properites of LDPE/CFA/Si-APP improve substantially compared with the pure LDPE. When the mass ratio of BF to Si-APP is1:1, The LOI value reaches to the maximum28, which raises62percent compared with pure LDPE, while the maximum heat release rate decreased from1479.6kw/m2to383kw/m2and total heat release decreased from108.0MJ/m2to69.95MJ/m2.