水解对SL-g-P(AA-AM)/PVP半互穿高吸水树脂结构与性能的影响

Effects of hydrolysis on structures and properties of SL-g-P(AA-AM)/PVP semi-IPN superabsorbent polymer

摘要:

以木质素磺酸钠(SL)、丙烯酸(AA)、丙烯酰胺(AM)和聚乙烯吡咯烷酮(PVP)为原料,过硫酸钾(KPS)为引发剂,N, N′-亚甲基双丙烯酰胺(MBA)为交联剂合成了SL-g-P(AA-AM)/PVP半互穿网络高吸水树脂。将SL-g-P(AA-AM)/PVP在NaOH溶液中进一步水解得到H-SL-g-P(AA-AM)/PVP。通过单因素优化实验考察了水解时间、水解浓度、水解温度以及搅拌速率对树脂吸水倍率的影响。利用FTIR、LNMR、XRD、TG和SEM对水解前后样品的结构、热稳定性和表面形貌进行了研究；测试了水解前后样品的溶胀性能、保水性能及重复使用性能。结果表明,在NaOH浓度为0.0125 mol/L,水解温度为75 °C,搅拌速率为400 r/min的条件下水解2 h得到的树脂吸水倍率可达2011.12 g/g,远高于未水解树脂的吸水倍率(1292.11 g/g),且水解前后树脂的溶胀行为均符合一阶与二阶溶胀动力学模型。H-SL-g-P(AA-AM)/PVP在质量分数为0.9%的NaCl溶液中的溶胀能力(123.65 g/g)高于SL-g-P(AA-AM)/PVP(97.41 g/g),但由于水解后-COO_^-增多,树脂在MgCl₂和FeCl₃溶液中的溶胀能力并未提升,且H-SL-g-P(AA-AM)/PVP的溶胀能力受溶液pH影响较大。此外,水解后树脂的保水性能优于未水解的树脂,且具有一定的重复使用性能。

Abstract:

A semi-interpenetration (semi-IPN) superabsorbent polymer (SL-g-P(AA-AM)/PVP) was synthesized by using sodium lignosulfonate (SL), acrylic acid (AA), acrylamide (AM) and polyvinylpyrrolidone (PVP) as raw materials, potassium persulfate (KPS) as initiator and N, N′-methylene bisacrylamide (MBA) as cross-linking agent. The effects of hydrolysis time, hydrolysis concentration, hydrolysis temperature and stirring rate on water absorption of resin were investigated by single factor optimization experiment. The structure, thermal stability and surface morphology of samples before and after hydrolysis were investigated by FTIR, LNMR, XRD, TG and SEM. The swelling, water retention and reusability of samples before and after hydrolysis were evaluated. The results showed that the resin obtained by hydrolysis under the condition of NaOH concentration of 0.0125 mol/L, hydrolysis temperature of 75 °C and stirring rate of 400 r/min for 2 h had a water absorption rate of 2011.12 g/g, which was substantially higher than that of the unhydrolyzed resin (1292.11 g/g). The swelling behavior of the resin before and after hydrolysis was complied with the first-order and second-order swelling kinetic models. The swelling ability of H-SL-g-P(AA-AM)/PVP in NaCl solution with a mass fraction of 0.9% (123.65 g/g) was higher than that of SL-g-P(AA-AM)/PVP (97.41 g/g), but the swelling ability in MgCl₂ and FeCl₃ solutions was not improved due to the increase of -COO^_- after hydrolysis. The swelling ability of H-SL-g-P(AA-AM)/PVP was greatly affected by the pH of solutions. Furthermore, the water retention performance of hydrolyzed resin was superior to that of unhydrolyzed resin, and it exhibited certain reusability.