Polypropylene (PP) blends with various molecular weight and isotacticity were prepared through Solution blending and Subjected to rapid melt quenching. Structural changes in the PP matrix during mesomorphic phase formation were measured by FTIR spectroscopy and wide-angle X-ray diffraction measurements. The blends with different molecular weight and isotacticity provided the pathway to understand their influence oil mesomorphic phase formation. It is observed that low molecular weight PP with low isotacticity forms mesomorphic phase, whereas high molecular weight and low isotactic PP does not lead to the formation of mesomorphic phase. (C) 2009 Wiley Periodicals, Inc. I Appl Polym Sci 113: 3181-3186, 2009