Yu Zhai

Effect of Carbon Black on the Properties of Polyimide Foams

Polyimide foams (PIF) contained carbon black were prepared from polyimide precursors by inflation process. The structure, compressive strength and heat-resistance of the PIF were studied. The FT-IR results confirmed the successful synthesis of PIF. Tgvalue of PIF with different content carbon black was over 255°C.With the increasing of carbon black content, Tgof PIF decreased. PIF decomposition temperature (Td 5%) was higher than 540°C,while the compression strength of PIF about 0.12MPa with low content carbon black.

Properties of High Solid Content UV Curable Waterborne Polyurethane Dispersions with Different C=C Content

Ultraviolet (UV) curable waterborne polyurethane(WPU) dispersions based on isophorone diisocyanate(IPDI), polypropylene glycol(PPG), dimethylolproprionic acid(DMPA) and pentaerythritol triacrylate(PETA) were prepared by the conventional method of anionic aqueous polyurethane dispersions. The structure of the ultraviolet (UV) curable WPU dispersions was studied by FT-IR. Stability, dispersion particle size and zeta-potential of the WPU dispersions were characterized. Effect of temperature on viscosity of the dispersions with different C=C content was also investigated. Results showed that all UV curable WPU dispersions had high solid content (48wt%) and showed remarkable mechanical stability. The viscosity of the dispersions decreased with temperature increasing from 20°C to 60°C. When C=C content varied from 0 to 1.05meq/g, the dispersion particle size was under 300nm, zeta potentials were less than -48.9mV.

Gas Separation Properties of Polyimide Membranes Based on 2,2-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane

A series of polyimides (PIs) by thermal imidization of polyamic acid (PAA) were prepared in order to investigate the gas separation property. The single gas permeability of He, H2, CO2, O2, N2 and CH4 were measured and compared in order to determine the effect of the reaction content and thermal imidization temperature on the gas separation properties. The results showed that the higher the thermal imidization temperature is, the more beneficial for the gas separation properties of the PI membranes. The optimum polycondensation reaction content on preparing PI was 25 wt%. The highest ideal selectivity of He/CH4, H2/CH4, CO2/CH4 and H2/N2 is 2814.88, 1652.38, 216.63 and 191.58, respectively.

Properties of Waterborne Polyurethanes: Effect of NCO/OH Ratio

Waterborne polyurethanes(WPUs) based on isophorone diisocyanate(IPDI), Polybutylene adipate (PBA) and dimethylolproprionic acid(DMPA) were synthesized by prepolymer mixing process. Effect of NCO/OH ratio on the properties of the dispersions was studied. The structure of the WPUs was studied by FT-IR. Besides the mechanical properties and water swelling of the films, the number average diameters of the dispersions and the viscosity of WPUs were characterized, results showed that all WPUs had higher solid content (over 45%). With higher NCO/OH ratio, WPUs had bigger dispersion size and lower dispersion viscosity; the casting film had higher water swelling, lower tensile strength, and more water-soluble substance.