Dynamics of Poly (butyl acrylate) and Poly (ethyl acrylate) with internal double bonds

In this paper, the changes in dynamics of Poly (butyl acrylate) (PBA) and Poly (ethyl acrylate) (PEA) after introducing internal double bonds (through copolymerizing with isoprene (IP)) were studied through sight of fragility theory. The dynamic fragility was determined. And the result shows that dynamic fragility indexes of PBA-co-IP and PEA-co-IP are smaller than PBA and PEA. Furthermore, the scaled dynamic mechanical spectra show that PBA-co-IP and PEA-co-IP have longer length of glass–rubber transition region. In one side, our work is well fitted to the universal theory that smaller fragility leads to longer soft dispersing in glass–rubber transition region. In the other side, adding internal double bonds is an effective way to weak fragility of polymers, which results in a broader transition region.