Preparation And Properties Of The Salt-resistance Water-swellable Rubber

In this thesis, there is a new experimental program that polyurethane(PU) resin was gradually replaced by the sodium polyacrylate resin(SAP) which was commonly used now on the market. Polyurethane resin was grafted with the nitrile rubber(NBR)and hydrogenated nitrile rubber(HNBR) by chemical grafting instead of physical blending method. The overall performance, salt and water absorption properties of the salt-resistance water-swellable rubber(WSR) were improved. The elasticity and strength and expansion properties in the salinity of the water of WSR were improved which can withstand the soak cycle, and the precipitation was very low. The thesis includes the following parts.In the first part, the water-swellable polyurethane resin was successfully synthesized. The influence of the molecular weight of polyethylene glycol(PEG) and the type of isocyanate to the hardness, water absorption, and expansion properties in different media salinity water was discussed. The results showed that the hardness and water absorption of PU resin which was synthesized by PEG-6000 were better than PEG-4000, but it was more brittle after expansion. The synthesis of PU resin With toluene diisocyanate(TDI) was better than the isophorone diisocyanate(IPDI) and has a better salt-resistance and water absorption. However, the hardness was high and the transparency of the test piece was not good. Compared with the WSR based on the PEG-4000, the WSR based on the PEG-6000 which was reacted with TDI has the best overall performance, and the salt-resistance water-swellable rubber was prepared.Water-absorbing polyurethane(PU) macromolecular reactive resin was synthesized by step-reaction polymerization reaction with polyethylene glycol, toluene diisocyanate and hydroxyethyl methacrylate as raw materials. The salt-resistance water-swellable rubbers were processed by water-absorbing polyurethane(PU) macromolecular reactive resin grafted by radical reaction with the double bond of nitrile butadiene rubber. The influence of the relative content of PU resin among the mixture of PU and SAP on the mechanical properties and the maximum mass swelling ratio(ΔWe) of the WSR were both studied. The results showed that with an increase of PU content in the mixture of PU and SAP, both the mechanical properties and the maximal weight swelling ratio(ΔWe) of WSR increased. When the pure PU reactive resin of 150 phr in the recipe used to compose NBR, The ΔWe of the prepared WSR was stabilized ataround 3.6 times, no precipitation phenomenon of water absorbing agent from WSR was also observed, and the WSR showed the better the salt resistance.In the second part, the PU/NBR chemical-grafted water swelling rubber was prepared and the recycling capacity for the WSR was mainly studied. Water-absorbing polyurethane(PU) reactive macromolecular resin was synthesized by step-reaction polymerization reaction with polyethylene glycol, toluene diisocyanate and hydroxyethyl methacrylate as raw materials. The salt-resistance water-swellable NBR rubbers were processed by graft radical reaction of PU resin with the double bond of nitrile butadiene rubber. The influence of the relative content of PU resin among the mixture of PU with SAP and DCP on the mechanical properties and the maximum mass swelling ratio(ΔWe) of the WSR were studied, respectively, the repeat water swellable efficiency was also studied. The results showed that with an increase of PU content in the mixture of PU and SAP, both the mechanical properties and the maximal mass swelling ratio(ΔWe) of WSR increased. When SAP resin was replaced by PU,the higher content of DCP in WSR, the overall properties was lower. When the content of DCP was 2 phr, the ΔWe keep above 2.04. The repeatable water swellable efficiency kept above 98 %.In the third part, the PU/HNBR chemical-grafted water swelling rubber was prepared. With the nitrile rubber was replaced by hydrogenated nitrile butadiene rubber,a new kind of WSR was prepared by polyurethane resin which was grafted with hydrogenated nitrile butadiene rubber, it was found that the comprehensive performance of the rubber especially the mechanical properties of the WSR which was synthesized by the resin with the molecular weight of polyethylene glycol 6000 which was added to the rubber was superior to that of the molecular weight of 4000. Water absorption performance gap has little difference.