Influence of the method of mixing on homogeneity and crystallization kinetics of blends of linear and branched polyethylene

The influence of mixing method—solution and melt mixing—on the homogeneity and crystallization kinetics of a series of blends of single‐site materials of linear polyethylene and ethyl‐branched polyethylene was studied by differential scanning calorimetry. Data obtained for heats of melting and crystallization, melting and crystallization peak temperatures, and melting and crystallization temperature profiles were essentially the same for the samples obtained by the two mixing methods. The results obtained can be interpreted as indicating that melt mixing is capable of producing homogeneous melts of these relatively low molar mass polymers, given that solution mixing is considered to give perfectly homogeneous blends. The heat associated with the high temperature melting peak after crystallization at 125°C of the blend samples, obtained by the two preparation methods, was higher than that of the linear polyethylene included in the blends, suggesting that a part of the branched polyethylene crystallized at 125°C. The unblended branched polyethylene showed no crystallization at 125°C. Samples obtained by powder mixing showed independent crystallization and melting of the linear and branched polyethylene components.