Preparation of superabsorbent by graft copolymerization of acrylic acid onto corn starch using K_2S_2O_8 and rare earths as initiators

K2S2O8 and rare earths(RE)were used as initiators to prepare superabsorbents by graft copolymerization of acrylic acid(AA)onto corn starch.The effects of monomer concentration,initiator K2S2O8 concentration,cross-linker concentration,reaction temperature and the concentration ratio of RE and K2S2O8 on the graft copolymerization were studied in terms of the water absorption capacity of superabsorbents.Results indicate that the optimum conditions obtained for the grafting of AA onto 5g starch are as follows:AA of 75.773 g/L,K2S2O8 of 0.437 g/L,RE of 0.874 g/L,cross-linker of 0.381 g/L and temperature of 70 ℃.The maximum water absorption capacity obtained is 740 g/g.The new method of graft polymerization is easily proceeded and controlled.The graft copolymers were characterized by infra-red spectroscopy,scanning electron microscopy and TG.Results characterized by IR and SEM give strong evidence for grafting of AA onto corn starch,and those characterized by TG reveal that the grafting of AA improves the thermostability of corn starch.

Radiation Induced Grafting of Acrylic Acid onto Viscose Rayon Fabrics and Its After-Effects

Radiation induced grafting of various polymers with different monomers proved to be an attractive means to modify the physical or chemical properties of polymeric materials or textile fabrics. In the present work, radiation induced grafting of viscose rayon fabrics, consisting mainly of cellulose fibers, with acrylic acid monomer has been carried out. The grafting yields have been thoroughly studied as a function of different applied experimental parameters. The impact of the graft yield on the physical properties of the fabrics such as tensile strength, elongation, swelling, moisture absorption, crease recovery angle and also the dyeing properties of the fabrics has been studied. The effect of increasing the contact time of the fabric and monomer solution, at room temperature, after stopping irradiation has been studied in detail as well as the effect of temperature on the irradiated samples also after stopping irradiation. The best grafting yield was obtained on irradiating viscose rayon fabric in methanol-water solvent containing acrylic acid monomer, at a dose 20 kGys, then heating for 7 hours at 80℃ and finally keeping the samples at room temperature for about 20 hours. That treatment significantly increased the final graft yield.

Radiation Induced Grafting of Viscose Rayon Fabrics with Some Acrylic Acid Derivatives and Styrene

Radiation induced grafting of viscose rayon fabrics, consisting mainly of cellulose fibers, with some acrylic acid derivatives, namely methyl acrylate, acrylamide and acrylonitrile, and also styrene, has been studied. The resultant graft yields have been determined as a function of the applied different experimental parameters. The impact of the graft yields on the physicochemical properties of viscose rayon fabrics such as swelling, moisture absorption, tensile strength, elongation at break, crease recovery angle and also dyeing ability of the grafted fabrics, has been also studied.

Studies on Graft Copolymerization of Acrylic Acid onto Ramie Fibers with Chromic Acid Initiation System

The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).

STUDY ON THE REACTION MECHANISM OF RADIATION GRAFTING OF ACRYLIC ACID ONTO POLYSTYRENE

It is difficult to find a solvent of grafting copolymer of acrylic acid onto polystyrene, thus it is not easy to analyse its structure by ordinary methods. Until now, many scientists considered that grafting reaction occurs on the main chain of polystyrene. In this work, the radiation grafting mechanism is studied with solid NMR and infrared. We have found that the grafting position is on the meso position of phenyl ring of polystyrene when the solvent is methanol and the matrix is polystyrene and a preirradiation method is used. It

接枝型天然橡胶基吸水膨胀橡胶的制备及吸水膨胀性能

以脱蛋白天然橡胶(DPNR)胶乳作为改性橡胶的基材,在氧化还原引发体系作用下,基于橡胶大分子链中烯丙基与乙烯基单体的自由基乳液接枝共聚反应实现丙烯酸(AA)在DPNR链上的接枝共聚,从而制备了一种亲水性AA接枝改性DPNR共聚物(DPNR-g-PAA),通过傅里叶变换红外光谱、核磁共振氢谱、扫描电子显微镜和称重法表征了DPNR-g-PAA的分子结构、断面形貌和吸水膨胀性能。结果表明,DPNR-g-PAA作为吸水膨胀橡胶,其薄膜吸水率可达85.06%,DPNR的表面透湿性显著提高;与传统物理共混或溶液接枝共聚反应制备吸水膨胀橡胶工艺相比,由自由基乳液接枝共聚制得的DPNR-g-PAA具有一定的优势。

Comparison of selective flocculation of low grade goethitic iron ore fines using natural and synthetic polymers and a graft copolymer

This study aims to beneficiate low grade goethitic iron ore fines using a selective flocculation process. Selective flocculation studies were conducted using different polymers such as starch amylopectin(AP), poly acrylic acid(PAA), and a graft copolymer(AP-g-PAA). The obtained results were analyzed; they indicate the enhancement of the iron ore grade from 58.49% to 67.52% using AP-g-PAA with a recovery of 95.08%. In addition, 64.45% Fe with a recovery of 88.79% was obtained using AP. Similarly, using PAA, the grade increased to 63.46% Fe with a recovery of 82.10%. The findings are also supported by characterizing concentrates using X-ray diffraction(XRD) and electron probe microanalysis(EPMA) techniques.

The Optimization of Synthesizing Graft Copolymer of Starch with Vinyl Monomers

The graft copolymerization of acrylamide （ AM ） / acrylic acid （ AA ） onto starch （ St- g-pAA and St-g-p（AA-co-AM） ） was carried out using an orthngonal test method. The combined effects of different reaction conditions on the water absorbency of the graft copolymers were optimized through mathematical statistical methods of range and square variance analysis. The maximum water absorbency was obtained when the ratio of dried starch to distilled water was 1 ： 8 （ w/w ）, the ratio of starch to monomer 1 ： 6 （ w/w ）, the initiator concentration 4.40 × 10^-3 mol/L, the crosslinker concentration 10.86 × 10^-2 mol/L, and the basicity to AA 0. 70（ mol/mol ）. Both the graft copolymers have an excellent water absorption capacity in distilled water aact in 0. 9wt% NaCl solution. It was also found that in distilled water the water absorbency of St-g-pAA was higher than that of St-g-p（ AA-co-AM） , while in 0.9wt% NaCl solution, the situation was just the reverse. The correlation between the water absorbeacy anct the nature of the solution anct the properties of the copolymers, which is related to the properties of the monomers, was discussed. The grafting of AA ancl AM onto starch was confirmed by the IR spectra of St-g-pAA and St-g-p（ AA-co-AM）.

用丙烯腈接枝改性脱蛋白天然胶乳及其自修复性能

采用乳液接枝共聚法,以脱蛋白天然橡胶(DPNR)为基体,丙烯腈(AN)和丙烯酸(AA)为单体,在叔丁基过氧化氢/四乙烯五胺引发体系下,合成了DPNR接枝AN和AA共聚物[DPNR-g-P(AN-coAA)]。通过红外光谱、核磁共振波谱等验证了AN及AA单体的接枝,研究了单体总量及m(AN)/m(AA)对改性DPNR力学性能的影响,以及修复条件对其自修复性能的影响。结果表明,在单体总量为10份(以干胶质量计)、m(AN)/m(AA)为10/1的条件下,DPNR-g-P(AN-co-AA)的最大拉伸强度和扯断伸长率分别为9.22 MPa和1365%,分别是初始DPNR的376%和133%。此外,体系中聚丙烯酸链段间的氢键相互作用使得DPNR-g-P(AN-co-AA)兼具优异的自修复性能,在50℃时愈合2 h可达到75.3%的自修复效率。

Dyes adsorption using a synthetic carboxymethyl cellulose-acrylic acid adsorbent

Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universaiity for removal of dyes through the chemical adsorption mechanism.

羧甲基纤维素接枝丙烯酸钠高吸水性树脂的合成与性能

根据自由基聚合和接枝共聚的机理 ,以过硫酸铵为引发剂 ,用羧甲基纤维素接枝丙烯酸钠制得高吸水性树脂 ,并且详细考察了原料配比和引发剂用量对接枝共聚物性能的影响 .实验结果表明 ,该接枝聚合物是一种较好的超强吸水材料 ,它吸自来水和盐水的量都远远大于其它吸水材料 .其吸去离子水为 1 0 0 0 g/g,吸 0 .9%的盐水为 1 4 0～ 1 6 0 g/g,且保水性能好 .

改性淀粉与丙烯酸接枝共聚物的合成及应用性能

研究经过热处理的改性淀粉与丙烯酸的接枝共聚反应。接枝共聚产物在 790cm-1、85 0cm-1(物理改性淀粉的特征吸收峰 )和 172 0cm-1(聚丙烯酸的特征吸收峰 )处的红外光谱验证了接枝共聚反应的发生。探讨了引发剂过硫酸铵浓度、丙烯酸浓度、反应温度和反应时间等因素对接枝率和接枝效率的影响。当 ρ(淀粉 ) =70 g/L、t =6 0℃、反应时间为 3h、c〔(NH4) 2 S2 O8〕 =3 0× 10 -3 mol/L、c(丙烯酸 ) =0 4 2mol/L时 ,合成胶粘剂的初粘力为 10 0 % ,吸水率为 15 0 14 % ,吸油率为 2 0 6 % ,其压制的纸板冲击强度为 3 2 5kN/m ,拉伸强度为 3 75MPa ,与纯淀粉粘接剂相比较 ,所压制纸板的应用性能得到较大的改善。

纤维素在离子液体中的均相接枝共聚

以离子液体为反应介质,过硫酸铵为引发剂,研究了纤维素与丙烯酸在离子液体中的均相接枝共聚,通过正交实验与单因素实验考察了单体用量、引发剂用量、反应温度和反应时间对接枝效果的影响。实验结果表明,接枝反应的最佳条件为:单体与纤维素质量比为4:1,引发剂与纤维素质量比为1:10,反应温度60℃,反应时间2h,在此条件下,接枝率可达96.7%。通过红外光谱进一步表明了接枝共聚物的生成。

淀粉-丙烯酸接枝共聚物的合成及产物结构表征

以木薯淀粉为主要原料,采用反相乳液聚合方法合成淀粉-丙烯酸接枝共聚物,通过正交设计对主要影响因素及反应条件进行研究,并用红外光谱、X射线衍射、热重分析等方法表征产物结构。实验结果显示,最佳合成工艺条件为丙烯酸:淀粉=3.5,丙烯酸中和度=83.3%,过硫酸钾和N,N-亚甲基双丙烯酰胺分别为淀粉用量的3.0%和0.3%,反应温度70℃,反应时间3 h,产物吸水率>800g/g。聚合过程中淀粉与丙烯酸发生了接枝共聚反应,并且接枝反应破坏了淀粉颗粒结晶结构,接枝产物趋于无定型结构。

富含纤维素类农作物秆与丙烯酸接枝共聚制备高倍率吸水树脂

用棉花秆、麦秆和玉米秆等富含纤维素类农作物秆与丙烯酸接枝共聚制备了高倍率的吸水树脂.研究了不同水质(去离子水、自来水及雨水)对接枝产物吸水性能的影响.采用棉花秆、麦秆、玉米秆与丙烯酸的接枝产物对去离子水的吸水倍率分别为930,790和630g/g,对自来水的吸水倍率分别为670,350和250g/g,用玉米秆/地瓜淀粉混合物制备的接枝产物对雨水的吸水倍率为540g/g.为棉花秆、麦秆及玉米秆等富含纤维素的农作物秆的深加工与应用开辟了一条途径.

高吸水性树脂的辐射接枝制备和结构表征

以天然多羟基淀粉和预先中和的水溶性单体丙烯酸为原料，采用γ射线辐射引发接枝共聚，制备高吸水性树脂，得到了吸蒸馏水为２３００倍，吸０．９％ＮａＣｌ为１４０倍的高吸水性树脂，在此基础上，用红外光谱、扫描电镜等分析手段对树脂结构进行了表征。

超细纤维素与丙烯酸接枝共聚反应规律的研究

用过硫酸盐氧化法使超细纤维素与丙烯酸接枝共聚。当反应温度 88℃ ,反应时间 5h ,单体用量 3 .75mol/L ,引发剂浓度 3 .5mmol/L ,接枝率可达 70 %以上。文章同时对其接枝反应的机理进行了探讨。

纤维素接枝丙烯酸制备高吸水树脂及树脂保水性能的研究

采用再生纸浆纤维素为分子骨架 ,接枝丙烯酸及其钠盐制备高吸水树脂。研究了再生纸浆种类及纸浆含量对产物吸水性能的影响 ,在确定了再生纸浆用量为 2 2 %的基础上 ,对引发时间、中和度、反应时间等工艺条件进行了研究优化。在以K2 S2 O8为引发剂 ,丙烯酸中和度为 70 % ,引发 30min ,反应 16h ,制备出吸水率达 10 5 0g/g ,6 0℃时水凝胶的水份散失通量为纯水的 5 5 %的高吸水树脂。本文还对高吸水树脂的保水性能进行了较为深入的研究 ,提出采用水份散失通量来评价高吸水树脂保水性能。

魔芋粉接枝丙烯酸(钠)超强吸水剂的制备

以过硫酸钾为引发剂 ,N ,N′ -亚甲基双丙烯酰胺为交联剂 ,魔芋粉与丙烯酸 (钠 )进行接枝共聚反应制备超强吸水剂。探讨了丙烯酸与魔芋粉配比、引发剂用量等因素对吸水性能的影响。结果表明 :在丙烯酸 魔芋粉 (质量比 )为 10 1,引发剂用量为 0 .15 0g ,丙烯酸中和度为 80 % ,反应温度为 6 0℃ ,交联剂用量为 0 .0 5 0g条件下制得的SAP吸纯净水倍率达 75 0倍 ,吸自来水倍率 2 79倍 ,且凝胶强度好。

悬浮法合成聚丙烯接枝丙烯酸

用过氧化二苯甲酰作引发剂以水相悬浮法合成聚丙烯接枝丙烯酸。通过反应条件、组分等因素对PP的接枝率和接枝效率的影响研究 ,确定较佳配比工艺条件 :溶胀时间 80min;反应温度 90℃ ;反应时间90min ;在氮气气氛中 ,丙烯酸 7% ;过氧化二苯甲酰 3 .3 % ;二甲苯 2 5% ;水和聚丙烯的重量比为 3∶1 ;若加入适量催化剂 ( 1 -1 .7% )异氰尿酸三烯丙酯能显著提高接枝率。用此PP -g-AA作PP/CaCO3 、PP/PA6复合物的相容剂 ,材料的力学性能有很大的提高。