Preparation And Properties Analysis Of Straw Composite Hydroxypropyl Methylcellulose Degradable Water-absorbing Material

The cellulose-based water absorbing material has a lightly crosslinked network structure,and has strong hydrophilic groups such as a hydroxyl group,a carboxyl group,an amide group and the like on the molecular chain.It can absorb water quickly and has good water absorption capacity.It is widely used in agriculture,industry,food and medical supplies.Hydroxypropyl methylcellulose is a derivative of cellulose with strong salt tolerance,water retention and pH stability.At present,hydroxypropyl methylcellulose is mostly prepared by graft copolymerization of acrylic monomers,but the biodegradability is not good.In this paper,hydroxypropyl methylcellulose(HPMC)or HPMC and straw were used as raw materials,respectively,and dissolved in NaOH/urea solution.Neopentyl glycol diglycidyl ether(NGDE)was added and reacted,purified by centrifugal washing,and then freeze-dried to obtain a water-absorbing material.The reaction factors(the amount of hydroxypropyl methylcellulose,the amount of NGDE,the amount of NaOH,the amount of urea,the amount of straw,the particle size of the straw,the temperature of the reaction)were studied.Excellent solution.The effects of the type,pH and temperature of the water-absorbing material on the liquid absorption were investigated.The liquid absorption rate,water retention performance(normal temperature conditions,pressurization conditions,and soil coating)and repeated water absorption properties were measured.The chemical structures were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and thermogravimetric analysis(TGA).The degradation properties of the materials were analyzed.4 g of HPMC was dissolved in 100 g of NaOH/urea/water solution(mass ratio 4:6:90),and the amount of NGDE was 13 ml,which was reacted at 55 ° C for 1 h.The obtained hydroxypropyl methylcellulose water absorbing material has the best water absorption ratio.The tap water rate was 17.3 g/g.The magnification of the 0.9% NaCl solution was 7.4 g/g.The rate of absorption of artificial urine was 8.5 g/g.2.5 g of HPMC and 80~100 mesh straw powder were dissolved in 100 g of NaOH/urea/water solution(mass ratio 7:12:81),and the amount of NGDE was 13 ml,which was reacted at 55 ° C for 1 h.The obtained straw powder composite hydroxypropyl methylcellulose water-absorbing material has the best water absorption ratio.The tap water rate was 22.4 g/g.The suction distilled water ratio was 32.8 g/g.The magnification of the 0.9% NaCl solution was 8.5 g/g.The magnification of the artificial urine was 10.6 g/g.Both water absorbing materials have good water retention and repeated water absorption properties.FTIR analysis indicated that HPMC and NGDE cross-linked,and the straw powder was partially dissolved in NaOH/urea/water solution and involved in the cross-linking reaction.XRD analysis showed that the diffraction amplitude decreased,the crystallization region was destroyed,and the material developed in an amorphous structure.SEM has characterized that the surface of the material has dense and continuous pore structure,the pore structure is evenly distributed,and it has good water absorption and water retention capacity.TGA analysis showed that the water absorbing material had good thermal stability and high temperature loss onset temperature.The degradability of two water-absorbing materials in soil was preliminarily studied.The degradation rate in different soil layers is forest land > street soil > farm soil,and the colony population of forest land is better than street soil and farm soil.HPMC water-absorbing material can degrade more than 30% in farmland soil for 90 days,about 42% in street soil for 90 days,and about 50% in forest soil for 90 days.The straw composite HPMC water-absorbing material can degrade about 40% in 90 d in farmland soil,about 50% in 90 d in street soil,and about 56% in 90 d in forest soil.Because the straw contains unreacted sugar,inorganic salts and crude protein,the decomposition rate of these substances is faster.The TGA test shows that the thermal stability of the material as a whole is good,and it tends to decrease with the increase of degradation time.