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This article was focused on the effects of the NCO/OH molar ratio and 2,2-bis(hydroxyl methyl) propionic acid (DMPA) content during prepolymerization on the physical properties of synthesized waterborne polyurethane (WBPU) by using the polycaprolactone-poly(ethyl glycol) -polycaprolactone triblock copolydiol (PCL-PEG-PCL) as the soft segment. The results showed that the particle size of the WBPUs' dispersion decreased with a decreasing NCO/OH molar ratio or increasing DMPA content. Regarding thermal and mechanical properties, the WBPUs had a higher T g 's and lower T m 's and a higher breaking stress and a lower breaking strain of film with the NCO/OH molar ratio or DMPA content increase. The increasing NCO/OH molar ratio was advantageous to the water vapor permeability (WVP)-breaking stress balance, but the effect of the DMPA content on the WVP was not significant. The WBPU with PCL-PEG-PCL as the soft segment had a smaller particle size in dispersion and a better WVPbreaking stress balance than those of WBPU with the blending PCL and PEG as the soft segment.

ABSTRACT:The surface structure and physical properties of polyethylene glycol series polyurethane (PEG-PU) membranes, in which were introduced hydrophobic polydimethylsiloxane (PDMS) component by the procedure of PU blending or of soft-segment copolymerization, were studied in this investigation. In the case of the blending process, the synthesized waterborne polyurethanes (WBPUs) of PEG-PU and of polydimethylsiloxane series polyurethane (PDMS-PU) were combined, whereas in the copolymerization process PEG and PDMS were taken as mixed soft segments to polymerize the WBPU. For the blending method, glass-transition and melting temperatures increased rapidly when a small amount of PDMS-PU was added to PEG-PU and reached a maximum with 5% PDM-S-PU mixed in. However, in the case of the copolymer method, thermal properties closely followed predicted values. From dynamic mechanical analysis studies it was found that a low PDMS-PU content ratio could increase the rubbery elasticity of PEG-PU membrane and improve its strength simultaneously in the blending method, and the copolymer method only caused PU to gain some natural complementary strength and elasticity. Electron spectroscopy for chemical analysis studies indicated that PDMS migrated to the surface much more easily in the blending method than in the copolymer method. The SEM studies also found that, in the blending method, the numbers of pores were less than those in the copolymer method.

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This study deals with the synthesis of some nonionic waterborne polyurethanes (PUs), using ethyldiamines of different chain length, such as ethylenediamine (EDA) and diethyltriamine (DETA), as the chain extender in the reaction, and examines the thermal properties, mechanical properties, and dyeing properties of the PU products and their blends. As far as each PU by itself is concerned, we found that the T g of the one made with DETA is the highest, followed by that with EDA, and the one with 1,4-butanediol (1,4-BD) is the lowest. The PU made with 1,4-BD as the chain extender has no T m , while the two others, using diamines as chain extenders, have a clear T m , the one with DETA being higher than that with EDA. However, the enthalpy data are just the opposite. The tensile strengths of the two PUs, made with diamines as the chain extender, are larger than that made with 1,4-BD, but their respective elongation properties are just the opposite. A comparison within PUs made with diamines showed that the one made with EDA is greater in both strength and elongation categories than that made with DETA. However, the one made with DETA is far superior to both of those made with 1,4-BD and EDA in their dyeexhaustion ratio, color yield (K/S), fixation rate, and color fastness. In respect to the various PU mixtures that we examined, we found that both PUs synthesized with EDA or DETA as the chain extender would have their T g 's greatly increased by blending in some PU made using 1,4-BD as the chain extender. Among them, in particular, a blend of PU, made separately with DETA and 1, 4-BD as the chain extender, showed great improvements in both tensile strength and elongation and also demonstrated better dyeability.