Supercritical Carbon Dioxide Assisted Solid-State Grafting Process of Maleic Anhydride onto Polypropylene
作者：Tao Liu,? Guo-Hua Hu,*,?,§ Gang-sheng Tong,? Ling Zhao,? Gui-ping Cao,? and Wei-kang Yuan*,?
關鍵字：無
論文來源：期刊
發(fā)表時間：2005年
The work reported in this paper aimed at exploring the advantages of using supercritical carbon
dioxide (scCO2) as an environmentally benign solvent and swelling agent for carrying out the
grafting process of maleic anhydride onto polypropylene in the solid state. The effects of scCO2
on the melting temperature and melting enthalpy of an isotactic polypropylene (iPP) were
investigated first in order to define the upper reaction temperature and CO2 pressure limits.
The effects of various factors on the grafted anhydride content and on changes in the molecularscale
and microscale structures of the resulting iPP were then investigated. Those factors included
the reaction time, monomer and initiator concentrations, reaction temperature, CO2 pressure,
and size of the iPP particles. Results showed that the scCO2-assisted solid-state grafting process
of maleic anhydride onto iPP did have some scientifically interesting and industrially relevant
advantages over the classical solid-state or melt process. Among them, it is worth pointing out
that the CO2 pressure itself constituted an additional and sensitive process parameter capable
of significantly modifying the overall reaction pathway and the product quality. For example,
without CO2, the solid-state grafting process was diffusion-controlled. Under scCO2, it became
reaction-controlled. The CO2 pressure could also regulate the anhydride content with ease. On
the other hand, the degree of iPP chain scission was not reduced under scCO2 compared to that
of the classical melt process.