| The technologies and history about producing the waterproof and breathable fabric were reviewed on the basis of a great number of references. Then the status in quo and developing tendency of it were summarized too. Meanwhile, the theoretic principle, advantages and limitations of every kind of technology were discussed at length.Further more, a recountal about shape memory polyurethane (SPU) on the aspects of its characteristics, development history, current situation and the application to the field of textile was given. Again, the mechanism concerning that how can the SPU be utilized to make an "intelligent" waterproof and breathable fabric was specially discussed, of course, the structure, characteristics and pertinent synthesis reactions of the SPU were introduced also.The two-steps technique was adopted in this research to prepare a lot of SPUs with different soft segment ingredient and average molecular weight, different rigid segment concentration, different molecular structure (linear or cross-linked) and different microcosmic structure (amorphous or crystallized) etc. These SPUs were prepared from 4,4'- diphenylmethane diisocyanate (pure MDI), polytetramethylene ether glycol (PTMG), polyethylene glycol (PEG) and polyoxyethylenetriol (PMG) plus 1,4-butanediol (BDO) as chain extender.In addition, many advanced analysis methods, such as scanning electron microscope (SEM), differential scanning calorimetry (DSC), gel phase chromatogram (GPC), wide angle X-ray diffraction (WAXD), dynamic mechanical thermal analyzer (DMA) and spectroscopic analysis (FT-IR) etc. were utilized to test the structure and properties of the SPUs, and the in-depth explanation was given also. At the same time, the performances of the fabric coated with these SPUs were studied by the aid of a hydrostatic water pressure test apparatus for textile and an installation used to test the water vapor transmission rate (WVT).Through the foregoing research, the various factors that would influence the properties of SPU and coated fabric (such as critical change temperature T_c, WVT,moisture permeability, the response precision and sensitivity to environmental temperature etc.) were clarified. Accordingly, the soft segment ingredient and average molecular weight, rigid segment concentration and the density of the hydrophilic aether bonds that the "intelligent" SPU waterproof and breathable coating agent should have were maken sure. Subsequently, a hydrophilic crystallized and cross-linked SPU with a Tc about of 20~26°C, witch is close to the optimum air temperature to human of 15.6~21.0°C was prepared. The SPU material has a definite water repellent ability, eminent moisture permeability and a good response precision and sensitivity to environmental temperature.Whereafter, the coating technics for the SPU material was studied preliminarily, involving coating procedure, processing conditions and so on. Several of dressing properties, suchlike the strength, handle and washability of the fabric coated with the SPU were appraised too.Finally, the moisture permeation behavior of "intelligent" waterproof and breathable finishing agent was demonstrated in detail.The study shows that the resistance to hydrostatic water pressure of the fabric coated with the SPU approaches to 8kPa;WVT will be increased from no more than 500g/m2.24hr to upwards of 2500g/m2.24hr within a range of 15~~18°C when environmental temperature is wormed from 10°C to 30°C. That is to say, the WVT and moisture permeability of the coated fabric have been respectively enhanced by 5~6 and 1.5~2.0 times, comporting a good response sensitivity and precision. Another deserved to be mentioned is that the response range of the coated fabric to environmental temperature is round about 18.0~27.0°C. So, the coated fabric can meets our desire for comfort at furthest.
|
PDF Full Text Request