The Synthesis Of Environmental Functional Hydrogel Material And Its Performance Of Water Retention And Controlled Release

Superabsorbent polymer is a kind of materials with superpower of absorbing water. Hydrogel, the product of superabsorbent after absorbing water and swelling, has the capability of keeping the water and slow release performance. This capability of superabsorbent has been widely applied in many fields including sorbent for heavy metals wastewater treatment, resistance to drought and holding moisture for agriculture, forestry and animial husbandry, lost circulation material for the oil field and structural engineering, drug delivery carrier for medical, etc. However, there still remain the problems in the application fundamental research of superabsorbent polymer, such as the inadequate objective performance assessment of the product, lack of unification theory on water retention mechanism. The settlement of these problems would provide guiding theory significance on manufacture, application and development of superabsorbent polymer hydrogel material.A superabsorbent polymer was prepared with potassium as initiator, N, N'-methylene-bis-acrylamide–like as crosslinking agent, acrylic acid as start materials, by solution radical polymerization. And the effects of types of crosslinking agent, concentrations of crosslinker and initiator, degree of neutralization of acrylic acid on swelling rate and solubility rate of the product was studied. Based on the experimental results, the best reaction condition to achieve higher swelling ratio and lower solubility is as follows: the reation temperation was 45℃, concentration of crosslinker is 0.08%, concentration of initiator is 0.10%, the degree of neutralization of acrylic acid is 60%, and the time of reaction is 10h.It is brought forward in the dissertation that the enthalpy of vaporization of superabsorbent polymer hydrogel was used to be the evaluating indicator for water retention performance of superabsorbent hydrogel. And a detection method was also established by measuring the enthalpy of vaporization of superabsorbent polymer hydrogel. Based on these, a research was conducted on the relationships between the water retention performance and its contributory factors, such as the hydrogel size, structural composition of hydrogel (crosslinking density, degree of neutralization of acrylic acid) and swelling ratio.The dissertation reveals that the superabsorbent hydrogel can be used as a matrix for urea releasing. And the effect of supersorbent polymer contributory factors, such as crosslink density, degree of neutralization on the release rate of urea in hydrogel is studied. Based on the experimental results, the slow releasing model of urea absorbed in supersorbent polymer hydrogel is established and provides theoretical support for controlling urea releasing rate.