Abstract:
Properties of polyethylene terephthalate (PET) and polypropylene (PP) can be enhanced by blending both in a specific proportion to get combined superior properties. To make a homogeneous blend, functionalization of PP can be done by grafting a required functional group on the main chain. Grafting of PP was done at varied concentration of MAH and BPO and its effect on the viscosity during and after the reaction was studied by torque rheometer and melt flow index. Functionalization of PP by free radical polymerization influenced its molecular weight owing to its chains breakage which was analysed by viscosity decrease during the reaction. At high percentage of grafting, lower molecular weight product was produced which was analysed by torque evolution. Alteration in PP structure also effected the crystallinity and melting temperature that was studied by thermal analysis. However, percentage crystallinity was enhanced by grafting due to the increase of chain’s packing and reduced chain entanglements. MAH-g-PP was used as compatibilizer in 60% PET blends. In all blends, PET’s percentage crystallinity was reduced compare to pure PET due to the hindrances of chains packing. Thermal properties of blends were improved as the first melting temperature was observed at 170oC and complete melting of blend occurred on 260 oC. Compatibilizer in PET/PP blend enhanced interactions in the blend resulted in homogeneous blend with less voids. 1% MAH-g-PP was the optimum value of compatibilizer in PET/PP blend that showed maximum uniformity in blend microstructure. Decrease in free space inside the blend hindered water molecules passage through films. Owing to this, water vapour permeability of blend was less compare to pure PET. Nonpolar nature of PP also influenced the water transmittance through the blended films. Blending of PET with PP in the presence of MAH-g-PP improved the processing of PET for film forming. All these properties of this blend make it suitable for packaging application.
