Studies On PVA-based Water-absorptive Sponge Material, Process Improvement

So far, low viscous PVA are often used to curing with aldehydes in the crosslinking system of PVAformaldehyde, and usually foaming with a chemical foaming agent--sodium hydrogen carbonate,which maycause the problems of bubble coupling and too large pore size. In this paper, in order to improve the problemmentioned above, different kinds of PVA were tried to be used with formaldehyde as a crosslinking system andchemical foaming agent took the place of physical foaming agent.Besides, aiming at the problem of harm tohuman body and environment pollution cause by formaldehyde’s toxicity, this paper also attempted to usepolyurethane prepolymer instead of formaldehyde, which helped to prepare a new kind of absorbent sponge.The results of the research on PVA formaldehyde absorbent sponge showed that，using30g of PVAsolution (PVA particles and water mass ratio=1:7) and5mL of formaldehyde as a crosslinking system，whileadding1.5mL of pentane，5.0mL of sulfuric acid and6.0g of starch in order to assisting foaming，and puttinginto40℃oven to react for1h after mixing evenly at room temperature，the absorbent performance of theabsorbent sponge was the best． The SEM test results showed that the bubble hole connecting with each otherwith moderate size; the density and water retention rate test showed that sponge had excellent apparentcharacteristics，hydrophilic，water holding capacity．In this study, we synthesized a series of sponge by adding different matters into the PVA, polyurethanewhich as the main material. Here, we synthesized a new type of environmental-benign PVA-polyurethaneabsorbent sponge by step foaming process, we studied the effect of each model of polyurethane, regulation ofthe catalytic system, ratio of each component, and each technological parameter. Through the way of using theenvironmental-benign way, appropriate technology route and improving technological parameter, we believethat we can produce environmental-benign PVA-polyurethane absorbent sponge.PVA-polyurethane absorbent sponge combined with the advantages of the PVA and polyurethane by wayof using the crosslinking curing method. The water absorption rate rasied from6～8g/g to20～25g/g whichwas about15g/g higher than the traditional PVA formaldehyde sponge, the rate of absorbing water rasied from2-3g/min.g to8-10g/min.g, It was found that the water-retention rate increased obviously by using thecrosslinking curing method. It can be seen that the PVA-polyurethane absorbent sponge can be widly used inprocessing of aquatic products, food, clinical medicine and water treatment, etc. We believe that the PVA-polyurethane absorbent sponge can change the status that low degree of curing of aldehydes, high content offree aldehydes and weak low temperature stability. The lower free aldehydes have a positive effect on theenvironment and the toxicity of this product. Furthermore, bubble hole can be smaller by incorporating theauxiliary blowing agent, which can improve the bubble hole, making it more uniform and fine.