Application of the SSA calorimetric technique to characterize LLDPE grafted with diethyl maleate

a linear low density polyethylene (LLDPE) was functionalized with diethyl m aleate (DEM) using different amounts of a peroxide as initiator. The modifi ed polymers were characterised by means of FTIR and H-1 NMR spectroscopy an d the percentage of grafted DEM was determined, When the initiator concentr ation is increased from 0.44 to 0.88 g per 100 g of polymer, the degree of functionalization also increases from 0.47 to 0.8 mol-% of grafted DEM per ethylene unit. The results gathered here indicate that in this case, the gr afting reaction preferentially occurs on the secondary carbons of LLDPE. Su ch a result was inferred by the use of the DSC based successive self-nuclea tion and annealing technique (SSA). The ability of SSA to induce molecular segregation during crystallisation and annealing proved to be very useful t o characterise the functionalized polyolefins prepared here. When the amoun t of initiator wne further increased to 1.76 wt.-%. the degree of functiona lization only increased marginally to 0.83 mol-%. Combined results by SSA, capillary rheometry and FTIR indicated that secondary reactions occur when only part of the initiator is used in the grafting reactions. Such secondar y reactions most probably produce long chain branching in the grafted polym er as indicated by the alterations in the melt now behaviour of this sample and the modifications of its FTIR spectrum.