Melt grafting of a long-chain unsaturated carboxylic acid onto polypropylene

The melt grafting of a long-chain unsaturated carboxylic acid such as oleic acid (OA) and undecylenic acid (UA) onto polypropylene (PP) in a Haake Rheocord RC90 mixer was studied. The influence of initiator concentration, monomer concentration and reaction temperature on grafting was investigated. The experimental results show that a higher degree of grafting was obtained using mixed initiators (DCP/BPO=1:1). Increasing the monomer concentration leads to an initial rapid increase in the degree of grafting. The addition of styrene reduced the degradation of PP as well as the degree of grafting. The monomer chain length influenced grafting significantly, the degree of grafting decreasing with increasing chain length of the grafting monomer. The results of differential scanning calorimetry (DSC) indicated that the crystalline properties of PP grafted with OA and UA were different from those of PP grafted with acrylic acid (AA), which may be attributed to the nucleation effect of the grafted long chain of OA and UA.