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Preparation, Structure And Property Of Styrene-N-Phenyl Maleimide-Acrylonitrile/Montmorillonite Nanocomposites

Posted on:2004-10-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:G D LiuFull Text:PDF
GTID:1101360125969764Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
In recent years, with the fast developing of polymer materials, the thermal properties of polymer materials become more and more important. Incorporating rigid N-substituted maleimide into the chain or compounding with clay are both effective ways to improve the thermal properties of polymers.Firstly, the affection of montmonllonite on bulk polymerization of styrene (St) was studied dilatometrically in this paper. The results show that the bulk polymerization rates increase with the increasing montmonllonite content and the affection become greater when the initiator concentration decrease. Montmorillonite participates the radical initiation reaction of the chain and the reaction order to montmorillonite (Cloisite 6A) is about 1.0, to initiator benzoyl peroxide (BPO) is about 0.5. The structure of the obtained PS/montmorillonite nanocomposites was affected by the change of the kinetics of bulk polymerization of styrene. Lower BPO concentration, larger interlayer distance, higher extent of delamination of clay and higher thermal decomposition resistance temperature were observed in the nanocomposite.The copolymerization of St with N-phenyl maleimide (PMI) in presence of montmorillonite was then investigated. It was found that the bulk and solution copolymerization rates increase to different extent and the intensity of alternating copolymerization was enhanced. But the emulsion copolymerization rate decreases and no obvious change of the intensity of alternating copolymerization was observed. X-ray diffraction (XRD) studies showed that emulsion intercalation polymerization is more favor for the preparation of St-PMI/montmorillonite nanocomposites.Polystyrene (PS)/montmorillonite, St-PMI/montmorillonite and St-PMI-AN(acrylonitrile)/montmorillonite nanocomposites were prepared by emulsion intercalation polymerization. The dispersibility of montmorillonite in the nanocomposites, solvent extract resistance property, thermal property, mechanical property and the modification effect as thermal property modifier for PVC of the nanocomposites were investigated.XRD and transmission electron microscope (TEM) study showed that the obtained polymer/ organo-montmorillonite(OMMT) nanocomposites have exfoliated structure while polymer/MMT(untreated montmorillonite) nanocomposites have partial exfoliated structure. Glass transition temperatures and heat decomposition resistance temperatures of the nanocomposites increase after intercalation compounded with montmorillonite. The melt apparent viscosities of the nanocomposites increase greatly under lower shear rates but with decreased non-Newton indexes. PS/OMMT nanocomposite has much higher mechanical property than PS/MMT because the interface interaction of polystyrene with OMMT is much higher than that with MMT. The dispersibility of montmorillonite in polymer matrix and the interaction between the montmorillonite layers with copolymer was greatly improved with the incorporation of polar unit PMI. And the difference between the properties of nanocomposites prepared by OMMT and untreated MMT becomes smaller. The dispersibility of montmorillonite in polymer matrix decreases with the further incorporation of polar unit AN. But the interaction between the MMT layer with copolymer improved more greatly and even the St-PMI-AN/MMT has higher property than St-PMI-AN/OMMT.Thermal property of PVC was improved after blended with the above nanocomposites. Mechanical properties, especially tensile property of the blends were improved under proper montmorillonite content.
Keywords/Search Tags:styrene, N-phenyl maleimide, acrylonitrile, montmorillonite, nanocomposites, polymerization kinetics, polyvinyl chloride
PDF Full Text Request
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