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 ( C n and C w) are calculated. The values of C w agreed well with the SCB contents obtained by 13C NMR (or TREF). The branching distribution index (BDI), which is equal to C w/ C n , 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.