Dynamic mechanical and thermal properties of a chemically modified polypropylene/natural rubber thermoplastic elastomer blend

Thermoplastic elastomers from blends of maleic anhydride-grafted natural rubber (NR-g-MAH) and maleic anhydride-grafted polypropylene (PP-g-MAH) have been prepared by melt mixing in a Brabender plasticorder. Grafting of each polymer was achieved in the molten state using dicumyl peroxide as the initiator. The effects on the dynamic mechanical and thermal properties were investigated over a wide range of temperatures. DMA analysis showed an increase of the glass transition temperature by 5 °C and a disappearance of the β transition peak for NR-g-MAH/PP-g-MAH with respect to the unmodified NR/PP blend. The DSC analysis showed a slight increase of the fractional crystallinity of polypropylene for the dynamically vulcanized and grafted blends. These effects were attributed to the enhancement of the interactions that developed between the two polymers as a result of the grafting.