A rapid quantitative method for determination of short chain branching content and branching distribution index in LLDPEs by DSC

A new method for rapid quantitative determination of short chain branching content (SCB) and branching distribution index (BDI) of ethylene/1-butene copolymers based on DSC is presented. Simple DSC thermograms of the samples are divided into small narrow slices with 1 °C width. The slice area is calculated with a program written with Mathlab software. Using the moment equations for branching distribution, the number and weight average short chain branching contents (Cn and Cw) are calculated. The values of Cw agreed well with the SCB contents obtained by 13C NMR (or TREF). The branching distribution index (BDI), which is equal to Cw/Cn, is an indicator of the broadness of SCB distribution. This parameter can be a good and rapid criterion for predicting the heterogeneity of branching structure of a sample.