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Study On Structure And Performance Of PP Holagen-free Flame Retardant Composites

Posted on:2011-03-23Degree:MasterType:Thesis
Country:ChinaCandidate:C S LiuFull Text:PDF
GTID:2251330425982766Subject:Materials science
Abstract/Summary:PDF Full Text Request
Selecting two kinds of flame retardants including magnesium hydroxide(MTH) andmicro-encapsulation red phosphorus(MRP), and four kinds of toughening agents includingPolyolyaltha Olfin(POE), Ethylene-propylene-diene monomer(EPDM), SEBS,Ethylene-propylene (EP), as subject investigated for comparison of those five tougheningagents on properties of polypropylene(PP) in this paper. Using PP as the carrier, maleicanhydride (MAH) as a grafting monomer and dicumyl peroxide(DCP)as an initiator, thecompatibilizer PP-g-M was prepared by adopting the method of melt grafting. The influenceof compatibilizers on mechanical properties, processability, flame retardant performance andmicrostructure was studied. The mechanical properties of PP halogen-free flame retardantcomposites were improved through mixing matrices, using PP-g-MAH and the elastomers,repsectively. The experimental results showed that the flame retardance of PP/MTHcomposites enhanced but mechanical properties declined when the MTH dosage increased.And when the MTH used with the MRP,the MRP could reduce the MTH dosage. ComparedPP/MTH/MRP composites (100:100:12) with PP/MTH composites (100:150),the impactstrength,elongation,tensile strength increased23.73%,38.52%and189%showed that therewas a good synergistic flame retardant effect between MRP and MTH. When the elastomerPOE amount was20phr, the impact strength of the material improved obviously, it couldreach3.68kJ/m2,102.2%more than the impact strength of PP/MTH/MRP. Adding8phrPP-g-MAH to the PP halogen-free flame retardant composites, the impact strength and tensilestrength increased to4.23kJ/m2and25.6Mpa respectively, which had a good flame-retardantand processing performance at the same time. The thermal behaviors,crystalline structure andmicro structure were texted and the result showed that the POE, as a nucleation agent,declined domains upgrading the crystal temperature and nucleation rate. Adding MTH madethe decomposition temperature to be ahead of time obviously. POE was concentrated aroundthe PP spherulites,hindered the crystal grain growth, thus causing the PP/MTH/POEcomposites crystallinity reduction. Adding PP-g-MAH could improve the compatibility of PPand MTH and further refined the grain. Taking42phr PP(1),40phr PP(2) and8phr PP(3) as resin matrix, the impact strength of PP/MTH/MRP/POE/PP-g-MAH(80/100/12/20/8)composites was7.98kJ/m2, the tensile strength was23.82MPa, LOI was27.28%, the meltindex was4.62g/10min, and the vertical combustion grade still reached FV-0.
Keywords/Search Tags:Polypropylene, Halogen-free flame-retardant, Elastomer, Synergistic flame retardant, Crystallization
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