Study On Modification Of Polyacrylonitrile Fiber By Blending With Soy Protein Isolated And Polyurethane

Soy protein isolated (SPI) has been considered recently as an alternative to petroleum polymer in the manufacture of adhesives, plastics, textiles et al. Soy protein is available from renewable resources and biodegradable. Utilizing soy protein for materials will help to solve environmental and petroleum resource problems and add value for agricultural by-products.Polyacrylonitrile (PAN) and polyurethane (PU) are general polymer material, and they have excellent performance, respectively. Blending is an important method in polymer manufacture, which may combine the advantages of both components. In this paper, the dispersion states and rheological properties of SPI in dimethylsulphoxide/urea, miscibility, interactions and rheological properties of PAN/SPI/PU system in DMSO, structure-property relationships of PAN/SPI/PU fiber were studied.Dimethylsulfoxide(DMSO)/urea was chosen as a mixture solvent system to dissolve soy protein. The dispersion status and properties of SPI in DMSO/urea were studied. The result showed that SPI has relatively high solubility in DMSO/urea mixture solvent and urea served as a key factor of dissolving SPI in the system. The solubility properties and gelation phenomenon of SPI were studied in DMSO/Urea. The effects, such as heating time, temperature and concentration of urea were discussed. SPI in the DMSO/urea mixture system exhibited different dispersion statuses with increasing of SPI content.Miscibility and interaction properties of PAN/SPI blend systems were studied by using methods of fourier transform infrared(FTIR), heat of mixing, dilute solution viscometry, phase contrast microscope. It was found that SPI/PU was partly miscilbility system and PAN/SPI, PAN/PU was immiscible system respectively, however there existed attractive interaction. In order to promote the compatibility, the main products of graft copolymerization of acrylonitrile and SPI (AN-g-SPI) and the alkaline hydrolysis polyacrylonitrile (HPAN) were used as the compatibilizers, and the mechanical properties of blends were improved observably.The SPI dispersed system in DMSO/Urea was shear-thinning fluid and flow behavior was different with increasing content of SPI because the change of dispersed state. The effects of SPI and PU on the rheological properties of PAN solutions were opposite. The Non-Newtonian index of PAN/SPI solutions decreased and corresponding structure viscosity index of that increased with increasing of SPI content on the whole. The fluid properties of PAN solution was worsened with the addition of SPI. The rheological properties of PAN/SPI/PU solutions were affected by the contents of SPI and PU. In any case, the increase of temperature contributed to the improvement of the fluid properties of blend solutions.The effect of temperature and concentration of coagulation bath, the multiple and corresponding distributive proportion of multiple drawing, temperature and time of drying, the type and concentration of crosslink agent on the properties of blend fiber were investigated. The result shown it was better to get good performance fibres when the concentration of coagulating agent was 60%, and the temperature of coagulation bath was 22℃, the drawing multiple in washing bath was 1.5-2 and the drying time was 15-20 minutes at 120℃.The effect of glutaraldehyde and glyoxal as cross-linking agent at coagulation bath on PAN/SPI fiber were studied. It was found that the mechanical properties of fibres used by glyoxal were improved.The methods of fourier transform infrared(FTIR), enzymatic hydrolysis, scanning electron microscopy(SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), mechanical property, dye adsorption, contact angle and moisture regain measurements were employed to investigate the structure and properties of PAN/SPI/PU fiber. The results show that the concentration of SPI in PAN/SPI/PU fibers determinately increased with increasing of addition SPI by using enzymatic hydrolysis though there was loss of SPI content compared with addition of SPI weight. The PAN/SPI/PU fibers were partly biodegrability system. The thermo degraded temperature slightly decreased with increasing of content of SPI in the PAN/SPI fiber. The dye adsorption for acidic dye and moisture regain of PAN/SPI fibers increased and the contact angle of that decreased with increasing of SPI ratio as well as compared with a referenced PAN fiber prepared via the same method.