Preparation And Properties Of Retarding Dilatation Water Swelling Natural Rubber Research

Water swelling rubber (WSR) is a new type functional polymer. It has unique properties by elastic sealing water and water swelling. WSR can reach swelling saturation in short period; because of it can swell immediately when soak in water. It cannot satisfy delayed plugging. Therefore, water absorption rate of WSR has been a wide question concerned by people all the time. This paper is aimed to prepare a new kind WSR, and the water absorbing ability of WSR is studied.We used chemical grafting method to prepare a new kind of WSNR. Initiator system, reaction condition and raw material ratio were discussed in the process of natural rubber grafted acrylamide reaction. Experimental results indicate that in this reaction we chose KPS/SHS system to prepare NR-g-PAM. With the increasing of acrylamide amount the grafting ratio and grafting efficiency were increased. When the initiator amount was added the grafting ratio and grafting efficiency were increased as well. The grafting ratio and grafting efficiency were increased first and then decreased when improved the reaction temperature, prolongation of reaction time and improved the latex concentration. When the monomer amount is75phr, initiator dosage is0.75%of monomer mass fraction, temperature is40℃, latex concentration is40%and reacts4hours the grafting ratio and grafting efficiency are34.5%and76.4%respectively.WSNR-Bt was prepared with bentonite suspension by using latex co-solidification method. The influences of bentonite for water absorption ratio and water absorption rate were discussed. Repeat water absorption, water retention capacity, salt resistant behavior and microstructure were analyzed. Experimental results show that with the increasing of bentonite dosage the water absorption ratio was reduced and water absoiption rate was slow down. When the dosage of bentonite is20phr, the water absorption ratio is14.6g/g in24hours and water absorption rate constant is8.995×102g/g/h. Water absorption rate was rapid and can keep stable when WSNR-Bt was soaked72hours in salt water. Thermogravimetric analysis indicated that the binding force of water with WSNR-Bt was enhanced. The combined water content increased12%. The water retaining capacity of WSNR-Bt under natural circumstance and hot circumstance are improved. Scanning election microscope analysis indicated that bentonite clay particle was dispersed uniformly in WSNR-Bt internal.WSNR-v was prepared with vulcanizing ingredient by using latex vulcanization method. The cross-linking density of WSNR-v and swelling index were analyzed in vulcanization. The influences of cross-linking density for water absorption ratio and mechanical property were discussed. Experimental results show that with the increasing of sulfur amount the cross-linking density of WSNR-v was gradually increased and the water absorption ratio is reduced. When the dosage of sulfur is0.75phr the swelling index and the cross-linking density are4.793and12.3×10-5mol/cm3respectively. The water absorption ratio is7.9g/g. WSNR-v has high elasticity modulus because of sulfur make the network structure become compact in vulcanization. The elasticity modulus can be more than5000Pa. DSC and TG analyzed found that water has three kinds of existing states in WSNR-v, respectively are Bound State, Free State and Combined State.