| Organic moisture absorbent is a new type of functional hygroscopic material due to their excellent moisture absorption and retention property. The resins, modified by chemical and physical modification, have a water-absorbent property by hydrophilic groups. In this paper, Polyacrylamide, Poly [acrylate-co-acrylamide], Poly [methacrylate-co-acrylate-co-acrylamide] and their composite materials with urea were be made with acrylamide, acrylate and methacrylate as monomers. The factors relating to the properties of moisture absorption, such as monomer concentration, dosage of initiator, reaction temperature and so on, were investigated systematically. The best reaction condition and the sequence of the factors influencing on hygroscopicity were based on the orthogonal experiment design. The mathematical correlation on various factors and moisture absorbency was obtained based on the multiple regression analysis. The composition and microstructure of polymer were described by means of infrared spectrum analysis and SEM analysis.Polyacrylamide and Polyacrylamide /Urea were synthesized with acrylamide as monomer by means of aqueous solution polymerization. The factors relating to the properties of moisture absorption, such as monomer concentration, dosage of initiator, crossing-linking agent concentration, reaction temperature and dosage of urea, were investigated systematically. The optimal synthesis conditions were as following: the monomer concentration, the crossing-linking agent concentration and the reaction temperature were respectively 26%, 0.12% and 50℃. Besides, the optimal dosage of urea was 30%.The result showed that the moisture absorption capacity of PAM is higher than the molecular sieve's and silica gel's under the condition of 25℃and RH=90%. Besides the moisture absorption capacity and the moisture absorption rate of PAM/U were higher than PAM cause of the urea attending. The reason was urea wrinkled surface area of polymer, which increased the effective surface area and then improved the moisture absorption rate. But the extra dosage of urea would lower the molecular weight of polymer.Poly [acrylate-co-acrylamide] and Poly [acrylate-co-acrylamide]/Urea were synthesized with acrylamide and acrylate as monomer by means of aqueous solution polymerization. The factors relating to the properties of moisture absorption, such as monomer concentration, dosage of initiator, crossing-linking agent concentration, monomer ratio, reaction temperature and dosage of urea, were investigated systematically. The max moisture absorbency of polymer reached 1.05g/g under the condition of 25℃and RH=90%. Also the results showed that the moisture-absorbing rate was very slow under low humidity. The moisture absorbency under relative humidity of 90% was ten times of that under relative humidity of 40%. And also the Infrared Spectroscopy confirmed the existence of the copolymer.The moisture content intuitive analysis table indicated the sequence of the factors influencing on hygroscopicity was shown as follows: monomer concentration> reaction temperature>AM concentration> crossing-linking agent concentration> dosage of urea> dosage of initiator.When the AM concentration was 100%, monomer concentration was18%, crossing-linking agent concentration was 0.22%, initiator agent concentration was 0.15%, urea concentration was 20% and the reaction temperature was 45oC, the max moisture absorbency was 1.05%.The mathematical correlation on various factors and moisture absorbency was obtained based on the multiple regression analysis: Y=a0+a1[N]2+a2[M]+a3[C]3+a4ln[I]+a5[U]+a6[T]3In which a0=1.351,a1=0.00000783,a2=-0.0259, a3=9.065, a4=0.0825, a5=0.00252, a6=0.0000007.The results of SEM showed that P(AA-AM)/U had a lot of micropore structure, which was produced by decomposition of urea. NH3 and CO2 were originated from the decomposed urea, played a role in pore making agent. And the result showed the dosage of urea and drying temperature impacted the moisture absorbing ability. The optimal conditions were the urea concentration was 20%-30% and the drying temperature was 120oC. There were two main reasons of moisture absorption property of P(AA-AM)/U better than P(AA-AM). Firstly, decomposition of urea produced pores, which increased the effective surface area and improved the moisture absorption rate. Secondly, urea was not only the pore agent, but also participated in reaction. A new hydrophilic group -N=C=O was generated.Poly [methacrylate-co-acrylate-co-acrylamide] and Poly [methacrylate-co-acrylate-co-acrylamide]/Urea were synthesized with methacrylate, acrylamide and acrylate as monomer by means of aqueous solution polymerization. The factors relating to the properties of moisture absorption, such as monomer concentration, dosage of initiator, crossing-linking agent concentration, monomer ratio and dosage of urea, were investigated systematically. The max moisture absorbency of polymer reached 0.885g/g under the condition of 25℃and RH=90%. Also the optimal monomer ratio was R(mMAA:mAA:mAM)=2:1:1. And the optimal urea concentration was 30%.
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