| Intelligent waterproof breathable fabric has become a research hotspot for its "smart" aspect in waterproof and breathable.It is suitable for a variety of harsh climate and environment and more comfort in wear.In this paper,firstly,three types of temperature-sensitive polyurethane waterproof and moisture permeable materials were synthesized using PBA,PTMG and modified castor oil as soft segments,PEG as hydrophilic component and MDI and BDO as hard segments.The relationships between the performances and compositions of polyurethane were studied.Secondly,the impacts of process conditions on the coatings and polyurethane coated fabrics were explored using the laboratory-made polyurethane solutions,through designing parallel experiments and orthogonal experiments with the coating fabric’s hydrostatic pressure and moisture permeability as the standard.Optimized process conditions were determined.Finally,under the optimum conditions,application properties of polyurethane waterproof and breathable finishing agent was investigated.The results showed that,with the reaction proceeded,the absorption peak of NCO group gradually decreased,until completely disappeared in IR spectrum.The DSC study found that the polyester polyurethanes’ thermal melting temperature were at 35 ℃ ~40 ℃,the polyether polyurethanes’ thermal melting temperature were at 12~20 ℃and 40 ℃ ~45 ℃,while polyester polyether polyurethanes’ thermal melting temperature were around 40 ℃.X wide angle diffraction results showed that the crystallinity of the prepared polyurethanes was greatly influenced by its compositions.The crystallization peak increased with the increase of the content of PEG 2000 and PEG molecular weight and decreased with the increase of hard segment content.Study on coating process showed that the water repellent finishing process can improve thewaterproof performance of the fabric under the high moisture permeability of the fabric.The optimized process conditions are as follows: coating thickness 0.10 mm,baking temperature140 ℃,baking time 2min.The results showed that the moisture permeability of the finished fabrics increased with the increase of PEG molecular weight and PEG2000 content,and decreased with the increase of hard segment content.The moisture permeability increased with the increase of temperature,and had a sharp increase at about 32℃.Which proved that the synthesized polyurethanes were more sensitive to temperature changes and had a certain "smart" property.The results of several washing experiments showed that the synthesized polyurethane has a certain durability.SEM photographs showed that the prepared polyurethane can form a dense nonporous film,hard phase distribution in the soft phase,and the fabric was covered by a layer of polyurethane film on the surface after coating. |
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