A new turbidimetric approach to measuring polyethylene short chain branching distributions

A new instrument to analyze the short chain branching distribution of polyethylenes has been described. Turbidity analysis of ethylene/α-olefin copolymers by turbidity fractionation analysis can provide short chain branching distribution information that is similar to CRYSTAF and TREF. In these experiments, the turbidity of a polymer solution is monitored while changing its temperature at a controlled rate. The turbidimetric response is to the precipitation or dissolution of the crystallized polymer at a given temperature. With an approach similar to CRYSTAF, the differential of the turbidity profile provides valuable SCBD information for polymers with broad and narrow compositions such as Ziegler-Natta LLDPE and homogeneous polymers catalyzed by single-site catalysts.