Kinetic Study on Extraction of Red Pepper Seed Oil with Supercritical CO_2

A mathematical model for extraction of red pepper seed oil with supercritical CO2was proposed.Some factors influencing the process were investigated,including operation pressure,temperature and extraction yield Xe(%).The model was solved by the method of weighted residuals and used to simulate the process numerically.The kinetic equation is expressed as Xe16.8606exp(t/9.98177)16.95457 and the simulation results are in excellent agreement with the experimental data.The optimal operating parameters are 30 MPa,318 K and 60 min.

Towards High Molecular Weight Poly(bisphenol A carbonate) with Excellent Thermal Stability and Mechanical Properties by Solid-State Polymerization

Poly（bisphenol A carbonate） （BPA-PC） was post-polymerized by solid-state polymerization （SSP） after supercritical CO2-induced crystallization in low molecular weight particles prepolymerized via melt transesterification reaction. The effects of the crystallization conditions on melting behavior and SSP of BPA-PC were investigated with differential scanning calorimetry （DSC）, Ubbelohde viscosity method and gel permeation chromatography （GPC）. The reaction kinetics of the SSP of crystallized prepolymers was studied as a function of reaction temperatures for various reaction periods. As a result, the viscosity average molecular weight of BPA-PC particles （2 mm） increased from 1.9 × 10^4 g/mol to 2.8 × 10^4 g/mol after SSP. More importantly, the significantly enhanced thermal stability and mechanical properties of solid-state polymerized BPA-PC, compared with those of melt transesterification polymerized BPA-PC with the same molecular weight, can be ascribed to the substantial avoidance of undergoing high temperature during polymerization. Our work provides a useful method to obtain practical product of BPA-PC with high quality and high molecular weight.