Starch Graft Copolymers for Water Treatment

Graft polymers produced by the reaction of starch with cationic, anionic and nonionic acrylic monomers show considerable potential as flocculating agents for treatment of industrial and municipal wastewaters, for beneficiation of mineral ores and for retention of clay in filled paper. Performance of the polymers depends on the nature of the system being treated and on the structure of the starch grafts. Percent add-on, grafting frequency, molecular weight of grafted chains and ionic charge are important variables in starch graft polymer structure that influence performance. Effectiveness of the polymers as flocculants has been demonstrated in laboratory tests and in on-site trials. Methods of preparation have been developed and the various polymers characterized.     

淀粉来源及预处理方式对淀粉接枝共聚反应的影响

以[Mn(H2P2O7)3]3-为引发剂,对不同来源淀粉与丙烯腈的接枝共聚反应进行了研究,考察了淀粉预处理方式对淀粉接枝共聚反应的影响.结果显示:用颗粒淀粉进行接枝共聚反应时,接枝效果受到淀粉颗粒大小的影响;用糊化后的淀粉进行接枝共聚反应时,最终制得产物的吸水率较高,并部分地依赖淀粉中直链和支链淀粉的含量.淀粉的预处理如糊化、氧化、酸解对接枝效果都有一定的影响.     

淀粉接枝共聚物高吸水性树脂工艺技术研究

研究淀粉接枝共聚物高吸水性树脂工艺技术。以玉米淀粉为原料，丙烯酸为单体，热分解型自由基为引发剂，建立高效的接枝共聚反应系统，研发“一步法”工艺生产高吸水性树脂。     

经纱上浆用淀粉接枝共聚物的开发与展望

接枝淀粉是经纱上浆中最有可能大批量取代PVA的环保型浆料，国内外在淀粉接枝共聚技术方面的大量研究表明，化学引发方法存在接枝物与均聚物分离提纯的难题；物理引发方法因辐射能量高，反应不易控制，会影响淀粉的本体性能；应用微波辐射技术对淀粉进行改性，使大分子链裂解，降低分子量具有提高反应速率和显著降低化学反应产生的废弃物对环境造成危害的优点。     

Synthesis of Poly(Methacrylic Acid-)Starch Graft Copolymers Using Mn-IV-Acid System

When starch was treated with KMnO₄ solution, MnO₂ was deposited overall the starch. The amount of MnO₂ deposited relied on the KMnO₄ concentration. Subjecting the MnO₂-containing starch to a solution consisting of monomer (methacrylic acid, MAA) and acid (citric, tartaric, oxalic or sulphuric acid) resulted in formation of poly(MAA)-starch graft copolymer. The magnitude of grafting, expressed as meq. -COOH/100 g starch, was determined by amount of MnO₂ deposited, MAA concentration, temperature and duration of polymerization as well as kind and concentration of the acid. Incorporation of cations such as Fe⁺³, Cu⁺² and Li⁺¹ had a significant effect on grafting. The highest extent and rate of grafting were obtained with citric acid and the least with sulphuric acid; tartaric acid stood in-mid-way position. The magnitude of grafting increased as the acid concentration increased till a certain concentration beyond which grafting levelled off. Similar trend was observed when the magnitude of grafting was related to the amount of MnO₂ deposited. The extent and rate of grafting increased by raising the polymerization temperature from 30° to 50°C then decreased by raising the temperature further from 60° to 70°C. On the other hand, grafting enhanced significantly by addition of Fe⁺³, Cu⁺² or Li⁺¹ and followed the order Fe⁺³ > Cu⁺² > Li⁺¹. A tentative mechanism for grafting of starch with MAA using MnO₂-acid system was elucidated.     

Synthesis of Starch Copolymers by Silicon Tetrachloride Plasma‐Induced Graft Polymerization

Corn starch was surface‐functionalized by 13.56 MHz RF SiCl₄‐plasma, in situ reacted with ethylenediamine for stabilization, and subsequently graft‐polymerized using dichlorodimethylsilane as monomer. SiCl₄‐plasma treatment was studied and discharge parameters were optimized. X‐ray photoelectron spectroscopy (XPS/ESCA), Fourier transformed infrared spectroscopy (FTIR), scanning electron spectroscopy (SEM), gas chromatography/mass spectroscopy (GC‐MS), and differential thermal analysis/thermal gravimetry (DTA/TG) proved the presence of a polydimethylsiloxane (PDMS) graft‐copolymer layer on the modified starch‐granule surfaces. These analyses show that the surface morphology of starch granules, the thermal properties, the swelling characteristic, and the hydrophilicity of starch were all changed due to the existence of a protective hydrophobic PDMS layer. It is suggested that the starch graft‐copolymer might find its applications as reinforcing component in silicone‐rubber materials for starch‐based composites.     

影响接枝氧化淀粉浆料性能的因素分析

研究影响接枝氧化淀粉浆料性能的因素。以过硫酸铵为引发剂,乙酸乙烯酯和丙烯酸丁酯为单体,氧化玉米淀粉为原料进行接枝共聚反应,测试了不同引发剂用量、单体用量、反应时间、反应温度条件下,接枝反应生成的接枝淀粉浆料浆液的黏度和对涤棉纱的黏着力。试验结果表明:过硫酸铵用量为单体总量的5.0%(单体总量为淀粉的20%)、乙酸乙烯酯∶丙烯酸丁酯为4∶6、反应时间为3.5 h、反应温度为55℃时所制得的接枝氧化淀粉浆料稳定性好,黏度适中,对涤棉纱的黏附性好。     

Preparation and Application of Starch Graft Poly(vinyl) Copolymers as Paper Coating Adhesives

A series of starch graft copolymers were prepared from commercial cornstarch products and vinyl monomers and were evaluated as adhesives in pigmented paper coatings. Hypochlorite oxidized (HO), acid modified (AM), and hydroxyethlated acid modified (HEAM) starches were reacted separately with acrylamide (AAm), acrylic acid (AAc), and acrilonitrile (AN) using ceric ammonium nitrate as the polymerization initiator to yield copolymers containing 2–45% synthetic polymer. Pigmented coating mixtures with 6–14 parts co-polymer/100 parts clay and 40–50% total solids were prepared and applied on one side of the paper stock using a hand-drawn doctor blade. Viscosities, adhesive strength, and wet-rub resistance of the coating adhesives and mixtures were determined. Adhesive strength of starch graft polyacrylamide (S-g-PAAm) copolymers containing as little as 12% PAAm was considerably superior to the commercial starches as paper coating adhesives. Adhesive strength of S-g-PAAc copolymers was similar to that of the HO and HEAM commercial starches, whereas adhesive strength of the S-g-PAN copolymers was poor. Copolymers that were prepared from the HO starch were slightly superior to those prepared from the AM and HEAM starches. Wet-rub resistance of the pigmented copolymer coatings was not improved over that of the coatings containing the commercial starches.     

Adsorption of Cu2+ by Crosslinked Graft Copolymers of Starch

With the use of acrylic acid(AA)as a monomer,humic acid(HA)and starch as raw materials,potassium persulfate(KPS)as initiator,and N,Ndimethylacrylamide(MBA)as a cross-linking agent,AA/HA/Starch graft copolymer was prepared and characterized by SEM and FT-IR.The effects of temperature,adsorption time,adsorbent dosage,pH value and Cu²⁺initial concentration of the solution on the adsorption performance of the crosslinked graft copolymer were also investigated.The results showed that the Cu²⁺adsorption capacity of the AA/HA/Starch graft copolymer increased firstly and then decreased with increasing adsorbent dosage and the initial pH value of Cu²⁺solution.With the increase of Cu²⁺initial concentration and the extension of adsorption time,the adsorption amount of Cu²⁺increased rapidly and then stabilized.And it decreased slightly with the increase of temperature.At pH value of 5.5,temperature of 298 K,adsorbent dosage of 50 mg,adsorption time of 125 min,and 100 mL Cu²⁺solution with Cu²⁺initial concentration of 100 mg/L,the Cu²⁺adsorption capacity of the crosslinked graft copolymer was 238 mg/g.The adsorption of Cu²⁺by the adsorbent followed the pseudo-second-order kinetic equation and Langmuir isothermal adsorption model,and the adsorption was attached to monolayer chemical adsorption.This study proved that AA/HA/Starch graft copolymer could be used as an efficient adsorbent for the removal of harmful and toxic metal cations such as Cu²⁺from industrial wastewater.     

Preparation and Characterization of Copolymers of Modified Starches and Polyacrylonitrile

Starch graft polyacrylonitrile (S-g-PAN) copolymers were prepared from a commercial unmodified cornstarch and from three chemically modified commercial cornstarch products including Amaizo 395 (highly acid modified, HAM), Amaizo 590 (highly hypochlorite oxidized, HHO) and Amaizo 791D (hydroxyethyl, highly acid modified, HEHAM). Using similar reaction conditions and ratio of monomer to starch (1:1), the percentages of PAN in the copolymers ranged from 39% for the unmodified starch to 48% for the modified starches. Only 5% of the PAN of the copolymer prepared from unmodified starch could be extracted by dimethylformamide (DMF) treatments compared to 22–28% for copolymers prepared from the modified starches. However, copolymers from the modified starches apparently contained relatively high proportions of low-molecular-weight copolymer along with homopolymer. Acid hydrolysis treatment of the DMF insoluble and DMF soluble fractions to remove starch from the various copolymers gave essentially quantitative yields of PAN. However, these PAN samples exhibited large differences in DMF solubility. The copolymer from the HHO starch was by far more soluble in DMF, had the lowest number average molecular weight, and had a grafting frequency of 2.5–3 times greater than those of the other copolymers. This study indicated that hypochlorite modified starch substrates may be particularly suitable for obtaining copolymers with widely different properties than copolymers having the acid modified starch substrates.     

Synthesis and Properties of Polyacrylamide-Starch Graft Copolymers

Graft polymerization of acrylamide onto rice starch was investigated under different conditions using potassium persulphate, benzoyl peroxide or potassium permanganate as initiator. This has led to establishment of the most appropriate grafting conditions for each of these initiators. Under these conditions grafting was characterized by two rates regardless of the initiator used. The first rate occurred during the initial stages of polymerization while the second during the later stages. The first rates of grafting for the three initiators were very close indicating the insignificant effect of the nature of the initiator on grafting during the initial stages of the reaction. On the other hand, the second rates of grafting exhibited the order: potassium persulphate < benzoyl peroxide < potassium permanganate, reflecting the role played by the nature of initiator during the later stages of the reaction. Substantial differences in solubility were observed between polyacrylamide-starch graft copolymers and unmodified starch as well as among copolymers prepared using the three initiators. Although the copolymers acquired higher solubility percent than the unmodified starch, yet nature of initiator, graft yield, structural changes in the copolymer occuring during grafting and the temperature of solubility measurement determined the solubility percent. Copolymers prepared using benzoyl peroxide or potassium persulphate showed lower viscosity than the unmodified starch. The opposite was the case with respect to copolymer prepared using potassium permanganate.     

S—g—PEMA接枝淀粉的合成

研究了以玉米淀粉和甲基丙烯酸乙酯为原料，以ＫＭｎＯ４／Ｈ２Ｃ２Ｏ４引发体系合成Ｓ－ｇ－ＰＥＭＡ。ＳＥＭ和ＩＲ证明了产物的正确性，产物的接枝效率可达８０％以上。     

接枝氧化淀粉工艺条件的优化

探讨能替代PVA的接枝变性淀粉的生产工艺条件。以氧化玉米淀粉为原料、过硫酸铵为引发剂、乙酸乙烯酯和丙烯酸丁酯为单体进行接枝共聚反应,并将所制得的接枝变性淀粉用于T/C 65/35 13 tex纱的上浆,用正交试验法探讨了引发剂用量、单体用量、反应时间、反应温度对浆纱耐磨性能、断裂强力、毛羽的影响试验得出最优工艺条件为过硫酸铵用量为单体总量5.5%,乙酸乙烯酯:丙烯酸丁酯为4:6,反应温度为55℃,反应时间为3.00h。认为在优化条件下制得的接枝变性淀粉浆料具有较好的上浆性能,可替代PVA用于涤棉混纺纱的上浆。     

阳离子改性接枝淀粉的合成及应用

在通氮的条件下，以氧化－还原引发体系引发淀粉，丙烯酰胺与阳离子单体（甲基丙烯酰氧乙基三甲基氧化铵）共聚，得到阳离子改性接枝淀粉，将改性接枝淀粉用作助留助滤剂，取得了满意的效果。     

壳聚糖与阳离子淀粉接枝共聚物作为造纸助剂的研究

研究了壳聚糖和阳离子淀粉接技共聚反应。共聚物作为造纸增强剂加入浆中，其应用效果在用量相同时，增强效果优于复配物，达到相同的使用效果时，用量少于复配物。共聚物在纤维间产生了离子键结合，增加形成氢键的能力，是提高纸页强度的主要机理。     

淀粉系列高吸水树脂的研究概况

高吸水性树脂是一种新型的功能高分子材料,由含强亲水性基团的单体经过适度交联使其能够吸收上百倍甚至上千倍的水。本文从吸水机理、聚合方法、影响因素及树脂的性能等方面综述了淀粉系列高吸水树脂的研究概况,并且介绍了淀粉接枝共聚高吸水树脂在生理卫生、医疗器械、土木建筑、农业、食品等方面的应用。     

淀粉糊化对接枝共聚反应的影响

以硝酸铈铵为引发剂将丙烯酸丁酯(BA)与淀粉(S)接枝共聚,考察了淀粉糊化对接枝反应的影响.结果表明:接枝特征参数(接枝率、接枝效率、接枝频率和支链的平均分子量)在淀粉糊化后都有所降低.可能是由于BA的疏水性,在水反应体系中有吸附到水/淀粉界面的趋势,淀粉糊化后这一界面将消失,使得BA与亲水性淀粉分子接触的机会减少.实验表明,在糊化淀粉接枝的情况下,加入适量的尿素有利于淀粉接枝共聚反应.     

淀粉接枝共聚物研究进展

鉴于淀粉接枝改性在生产生活中日趋重要的地位和相关研究的日新月异,从接枝物的接枝参数,引发方式,物化性能,表征手段等方面综述了近年来淀粉接枝改性方面的相关研究及其发展趋势。     

Cationisation of Starch Granules by Graft Copolymerisation

A method is presented to cationize granular starch by heterogeneous graft copolymerisation by using a redox-initiator. The graft content that can be reached depends on the kind of starch used and on the nature of the chosen monomer. Among the monomers tested a cationic methacrylic ester with acrylamide as co-monomer was most effective to reach a high degree of ionicity. The modification fosters swelling, but hydration proceeds without impairing the morphology and the gelatinization temperature of the starch. Cationically grafted starch shows less retrogradation. The aim to modify exclusively the surface of the starch granules to obtain optimal accessibility of the cationic charges was not fully reached. Basically the cationic monomers are grafted within the peripheral layers of a starch granule but at increasing graft contents an increasing part of grafting takes place mainly at the surface of the granule.     

淀粉系列高吸水树脂的研究概况

高吸水性树脂是一种新型的功能高分子材料,由含强亲水性基团的单体经过适度交联使其能够吸收上百倍甚至上千倍的水.本文从吸水机理、聚合方法、影响因素及树脂的性能等方面综述了淀粉系列高吸水树脂的研究概况,并且介绍了淀粉接枝共聚高吸水树脂在生理卫生、医疗器械、土木建筑、农业、食品等方面的应用.