In situ Raman spectroscopic investigation of olefin multiblock copolymers during melting and crystallization

The crystallization behaviors of olefin multiblock copolymers were investigated by Raman spectroscopy. A new approach was proposed to fulfill the Raman three phase analysis. The crystallinity obtained from such approach is well consistent with the method using melt Raman spectrum as a reference. It is found that both the Raman total crystalline fraction and the Raman orthorhombic crystalline fraction are affected by the hard block content of OBCs. Non-isothermal experiments on melting and crystallization illustrate that Raman spectrum and DSC can give identical transition temperatures. However, Raman spectrum analysis shows two distinct features during crystallization and melting of OBCs, namely the disappearance of all-trans noncrystalline phase at temperature much higher than the melting point and the dynamic balance of the interfacial phase fraction.