EFFECT OF MOLECULAR ARCHITECTURE OF PEON STRUCTURAL CHANGES OF PVC IN PVC/PE MELT-BLENDC. Thongpin, O. SantaviteeMaterials Science & Engineering, Faculty of Engineering and Industrial Technology,Silpakorn University, Sanamchandra Palace Campus,Nakornpathom, 73000, THAILANDEmail: firstname.lastname@example.orgN. SombatsompopPolymer Processing and Flow (P-PROF) GroupSchool of Energy & MaterialsKing Mongkut’s University of Technology Thonburi (KMUTT)Bangmod, Bangkok 10140, THAILANDEmail: email@example.comAbstractThis paper studied the effect of molecular architectureof PE on structural changes of PVC in PVC/PE blends.The thermal property results indicated that PE in the blendbetween PVC and PE affected the degradation mechanismof PVC. This was explained in terms of a macro-radicalcross-recombination reaction between PVC and PEmolecules which was confirmed by considering thechemical shift in Carbon-13 Nuclear Magnetic Resonance.The changes in decomposition and glass-transitiontemperature of PVC in PVC/PE blends were also affectedby types and melt flow indexes of the polyethylene.IntroductionPoly(vinyl chloride) PVC, is one of the most widelyused plastics that can be processed to be both flexible andrigid finished articles. The production of PVC articles inmost processes (such as injection moulding and extrusion)generates substantial quantities of scraps which would belikely be re-used or recycled. One of the major problemswhen recycling or re-using the PVC scraps is thermaldegradation. The degradation of PVC is usually proceededby a dehydrochlorination process which results in theformation of long conjugated double bonds or polyenesequences (-CH=CH-) n , thereby causing a color change.The dehydrochorination process becomes even more rapidin the presence of oxygen, which then results in theformation of carbonyl groups . The polyene sequencesformed during the degradation can then lead to crosslinkingand chain scissions. The properties of the recycledPVC have been widely studied in literatures [2-4].Sombatsompop et al [5-6] studied the recyclingpossibilities of various PVC products (pipes and bottles,and cables) in terms of process-abilities, mechanical andthermal properties, and morphological properties as afunction of recycled PVC content and types of recyclates.Overall results indicated that the addition of PVCrecyclates strongly affected the rheological, mechanicaland thermal properties of PVC products, the optimumcontent to be added being dependent on the types (whichwere associated with the initial chemical compositions ofPVC compound) and the loading level of PVC recyclates,and UV light .It is widely known that PVC is mostly used inpackaging applications such as bottles and blisteredproducts. It is likely used with other types of plastics suchas polyethylene. This then makes the recycling moredifficult and interesting. Although there have been manyresearches investigating the structural changes of PVCduring the recycling process, only a few studies havereported on the structural change of PVC in PVC/PEblends. It has been confirmed that the presence of PE inPVC affected the structural changes and the degredationmechanism of PVC . Arnold and Mound  reportedthat PVC could degrade faster with the presence of 2%MDPE due to the PE radicals occurring from thermomechanicaldegradation of PE which then consumedthermal stabilizer in PVC.This paper studied the thermal property changes ofPVC in PVC/PE melt blends by considering the effects ofPE molecular architecture and content. The blends werecharacterized using TGA, DMA and 13 C-NMR techniques.Raw materialsExperimentalThe polymer matrix used in this study was PVCcompound supplied by Thai Plastics and Chemicals Co.,Ltd. (Bangkok, Thailand), having a MFI of 5 g/min and aK value of 58. Various grades and MFI values ofpolyethylenes used, including their suppliers, were listed inTable 1.