Preparation And Properties Of Natural Macromolecules Based Superabsorbent Polymers

Superabsorbent polymers are a kind of functional polymers, which can absorb hundreds or thousand times its own weight of water and retain them even under pressure. Cellulose, as common natural polymer, is readily available and inexpensive. Humic acid series can increase the soil fertilizer and stimulate plant growth. The current superabsorbent products exhibit good water absorption capacity, but the repeated absorption water ability is weak, causing high production costs, which is not conducive to large scale application. The introduction of natural macromolecules into the preparation of superabsorbent polymers, then applied to agriculture means a lot. To meet the special requirements of superabsorbent polymers used in agriculture and forestry, developping the novel superabsorbent polymers with high water absorption property and good reused property under practical drought conditions are significant.Firstly, we prepared the sodium humate-based superabsorbent polymers and cellulose-sodium humate double-based superabsorbent polymers in solution polymerization based on our previous research. Experiments of processing sodium humate-based superabsorbent polymers in solution polymerization showed that when the initiator concentration was 2.0%, sodium humate and ratio reached 1:5, the product in distilled water, tap water and 5wt% urea solution got a good performance on the whole. The swollen behavior of the products in distilled water was more aligned with first-order kinetic model. Practical application showed that the best water retention ratio (47.52%) was achieved when the content of humate sodium-based superabsorbent was 1%, while, the optimal effect on plant growth was achieved when the content was 0.5%. At the same time, the polymer also exhibited certain biodegradability. Compared to the preliminary results of cellulose-based superabsorbent polymers, the absorbent and retention water properties of cellulose-based superabsorbent polymers were superior to sodium humate-based superabsorbent polymers.Experiments of processing cellulose-sodium humate double-based superabsorbent polymers in solution polymerization showed that the mass ratio of cellulose and sodium humate had a greater impact on product performance. When mass ratio was 1:3, the absorbent properties of the product was excellent(401.93g/g), two natural molecules in reaction systems exhibited synergistic effect; and when mass ratio was 1:5, the performance of the absorbent product was poor, two natural macromolecules in reaction systems exhibited competitive behavior. Water retention tests and plant experiments results showed that cellulose-sodium humate double-based superabsorbent polymers were better than sodium humate-based superabsorbent polymers.In order to reduce energy dissipation, improve production efficiency, a new microwave irradiation method was followed to synthesis cellulose-based superabsorbent polymers and cellulose-sodium humate double-based superabsorbent polymers. The optimal reaction parameters of microwave irradiation prepared cellulose-based superabsorbent polymers were Microwave power 350w and reaction time 3min. In the meanwhile, the optimum reaction parameters of sodium humate-based superabsorbent polymers were microwave power 560w and reaction time 5min. The performances of cellulose-based superabsorbent polymer prepared by microwave irradiation method are superior to the resulting product prepared by conventional solution polymerization method. The optimal cellulose-based superabsorbent polymer exhibits higher water absorbency ratio, water retention ratio and better reuse property. Comparison of the two materials shows that cellulose-sodium humate double-based superabsorbent polymers and the cellulose-based superabsorbent exhibit different micro-structures, resulting in absorption(665.3g/g) is higher than the cellulose-based superabsorbent polymer(629.51g/g), but its repeat performance and water-retention ratio are inferior to cellulose based superabsorbent polymers.