Off-campus UMass Amherst users: To download campus access theses, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users: Please talk to your librarian about requesting this thesis through interlibrary loan.
Theses that have an embargo placed on them will not be available to anyone until the embargo expires.
Master of Science in Chemical Engineering (M.S.Ch.E.)
Year Degree Awarded
Month Degree Awarded
Polypropylene, crystallization, physical gel point, gel stiffness
Long chain branched polypropylene (LCBPP) crystallizes rapidly and with high nucleation density. The origin of this fast crystallization process is not well understood. It has been attributed to its complicated molecular architecture. In this research, we explore isothermal crystallization of LCBPP, 5%LCBPP and linear polypropylene (LPP) through rheological, thermal, microscopy and optical measurements at different experimental temperatures. The time resolved mechanical spectroscopy technique was used to predict the liquid-to-solid transition (gel point) at different crystallization temperatures (supercooling rates) in order to understand the structure during the crystallization process.
The crystallization process of LCBPP was completed in time scale less than that of 5%LCBPP and LPP at different supercooling rates. This has been observed in all crystallization experiments using DSC, SALS and Rheometery. LCBPP exhibit stiff behavior at gel point compared to 5%LCBPP and LPP which imply that the small spherulites observed under polarized microscopy are stiff. Understanding of the rheological behavior during crystallization process will help to develop polymer with different processing conditions and applications.
Horst H Winter