A simplified moment model for prediction of long-chain branching during peroxide modification of HDPE

A simplified moment model was developed and applied in prediction of long chain branching during peroxide modification of HDPE. Moments modeling with two different approaches were performed at different initiator concentrations. In the second developed simplified model, in addition to the prediction of average molecular weights (M-n and M-w) and concentration of vinyl groups, the prediction of long-chain branching (tetra-functional and tri-functional branches) and also determination of gel point are all possible. In the new model, there exist differences between the chains with or without vinyl and backbone and terminal macro radicals and the type of probable terminations. The results of the new simplified moment model, based on zero or one vinyl per molecule assumption, is very close to those of models based on two-dimensional distribution which allows for unlimited number of vinyl groups on a molecule. The modeling results via moment methods were in good agreement with the experimental results.