A novel waterhorne polyurethane (WPU) was prepared using sodium N, N-bls ( hydroxyethyl) -2-aminoethane sulfonate(BES-Na) as chain extender. Characterizations with FT-IR and DSC were carried out in oi-der to investigate the influence of BES-Na content and NCO/OH ratio on the properties of WPU emulsions and films. The results indicated that with increasing BES-Na content, the average particle size of WPU emulsions decreased from 237.3nm to 61.2nm and the size distribution narrowed down. Meanwhile, the mechanical properties of the films were improved. For examples, the tensile strength of WPU. films was enhanced from 16.07 MPa to 24.67 MPa, elongation at break was changed from 478.73% to 724.07%, and the water absorption was increased from 6.82% to 13. 030%. Under the same experimental conditions but increasing NCO/OH ratio, the average particle sizes of WPU emulsions were increased from 77.6nm to 335.7nm but the distribution widened out. Also with increasing NCO/OH ratio the tensile strength was increased from 11.46 MPa to 22.28 MPa, while the elongation at break was decreased from 555.61% to 22.9% and the water absorption was decreased from 12.19% to 10.27%.%制备了以N，N-（2-羟乙基）-2-氨基乙磺酸钠（BES—Na）为亲水扩链剂的磺酸型水性聚氨酯，采用FT—IR、DSC对水性聚氨酯的结构进行表征，并研究了BES—Na含量和NCO／OH值对水性聚氨酯乳液和薄膜性能的影响。研究表明：随着BES—Na含量的增加，乳液粒径分布区间变窄，平均粒径由237．3nm减小至61．2nm，薄膜的力学性能有较大提高，拉伸强度由16．07MPa增至24．67MPa，断裂伸长率由478．73％增至724．07％，硬度增大，吸水率由6．82％增至13．03％；随着NCO／OH值的增大，乳液粒径分布变宽，平均粒径由77．6nm增至335．7nm，薄膜拉伸强度由11．46MPa增至22．28MPa，而断裂伸长率由555．61％降至22．9％，薄膜逐渐变得脆硬，硬度增大，吸水率由12．19％降至10．27％。
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