Zhen Ge

Preparation and properties of waterborne siloxane-containing polyurethane for moisture permeable textile coating

Abstract Waterborne siloxane-containing polyurethanes (WSPU) were prepared by polyaddition reaction using poly(tetramethylene oxide)glycol (PTMG), polyethylene glycol (PEG), and α,ω-aminopropyl polydimethylsiloxane (APDMS) as mixing soft segments; 2,2-di(hydroxymethyl)propionic acid, as a hydrophilic chain extender; 1,4-butanediol and isophorone diisocyanate as hard segment; triethylamine as a neutralization agent. The thermal properties of WSPU films were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermal gravimetric analysis (TGA). The mechanical properties of WSPU film were also investigated. Water vapor permeability (WVP) was examined according to GB_T 12704-1991. The DSC and DMA results indicated that there is a micro-phase separation in the WSPU film. The incorporation of APDMS into PU made the thermal stability of hard segment worse while that of soft segment better. The elasticity of WSPU was improved when the APDMS content was not more than 10%, the vapor permeability of coated fabric increased firstly and then decreased as the APDMS content increased, which was resulted from the hydrophilicity change and microstructure change of membrane. When 10% APDMS was incorporated into the WSPU, the WVP of coated fabric was 2130.15 g/(m2·24h), equal to one coated with a widely used solvent-based PU sample (UECCOAT), and the water resistance (WR) reached 30.0 KPa.

Study on Epoxy Resin Toughened by Epoxidized Hydroxy-Terminated Polybutadiene

Epoxy resin (EP) was toughened by epoxidized hydroxy-terminated polybutadiene (EHTPB), with the corresponding modified epoxy resin being prepared. In this paper, the microstructure of EHTPB-modified epoxy resin was characterized, while the influence of different contents of EHTPB on curing kinetics, mechanical properties, morphology, thermal properties, dynamic thermomechanical (DMA) properties and crosslink density of the modified epoxy resin were also discussed. The results showed that the EHTPB-modified epoxy resin was successfully prepared and cured completely. The activation energy (Ea) of the modified epoxy resin decreased after the addition of EHTPB. With an increase in the EHTPB content, the tensile strength (σm) of the modified epoxy resin decreased and the breaking elongation (εb) increased gradually. The initial decomposition temperature (T5%) and glass transition temperature (Tg) of the modified epoxy resin decreased with an increase in the EHTPB content. The modified epoxy resin had a rough fractured surface and the interface was blurred, presenting a ductile fracture.