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1.
Amal A. Aly 《Starch - St?rke》2006,58(8):391-400
Anionic starch derivatives bearing carboxyl groups were prepared by reacting maize starch and hydrolyzed maize starch with a previously synthesized citric acid adduct (2‐hydroxy‐3‐chloropropylcitric acid) using the dry process. Different factors affecting the preparation, i.e. catalyst concentration, citric acid adduct concentration, duration and temperature have been studied. The modified starch was characterized by IR spectroscopy, X‐ray diffraction analysis and scanning electronic microscopy. The anionic starch derivatives were evaluated as flocculants. Different factors affecting the flocculation efficiency of the prepared flocculants were studied. These factors include effect of dose, acid content, pH of the flocculation medium and molar mass. The anionic starch samples were chelated with different metal cations such as Cu2+, Co2+, Mg2+, and Hg2+, in the form of acetates, chlorides and sulfates. 相似文献
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A novel starch graft copolymer containing sulfobetaine moieties in the side chains was synthesized by grafting the sulfobetaine zwitterionic monomer 3‐dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (DMAPS) onto potato starch in the presence of the ceric ammonium nitrate (CAN) / acid initiation system. The effects of the concentrations of CAN and DMAPS, the pH of the reaction medium and the polymerization temperature on the grafting reactions were investigated in terms of the grafting percentage (GP) and grafting efficiency (GE). When the CAN concentration, the pH of the reaction medium or the reaction temperature increased, GP and GE were found to first increase and then to decrease. The increase of DMAPS concentration resulted in a significant enhancement of GP and GE. Furthermore, the thermal degradation of such graft copolymer was studied under air atmosphere at various heating rates, and the corresponding activation energy of the degradation was determined by Ozawa's method. 相似文献
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Cationic acetylated starch‐g‐poly(styrene‐butyl acrylate) surfactant‐free emulsion (CAS‐g‐poly(St‐BA)) was synthesized by graft copolymerization of styrene (St) and butyl acrylate (BA) onto CAS using FeSO4–H2O2 redox initiator. The maximum graft of 55.68% was derived when H2O2 concentration, monomer concentration, and St/BA ratio were 9%, 130%, and 1:1, respectively. The results obtained from FTIR, NMR (H1 NMR and C13 NMR), XRD, SEM, and thermogravimetric analysis (TGA‐DTG) confirmed graft copolymerization of St and BA onto CAS. And it was demonstrated that film‐forming properties of starch were greatly improved via grafting St and BA onto starch. It was also found that paper sized with CAS‐g‐poly(St‐BA) exhibited higher ring crush index and bursting strength than paper sized with cationic potato starch (CS) and CAS, as well as much lower water absorption, which is further verified by contact angles results. 相似文献
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羟丙基化对木薯淀粉糊性质的影响 总被引：8，自引：0，他引：8
羟丙基化对改善木薯淀粉糊的性质具有重要作用。作者用不同醚化程度的羟丙基木薯淀粉进行试验，测定其Ｂｒａｂｅｎｄｅｒ粘度性质、冻融稳定性和糊透明度。结果表明，羟丙基化能大大提高淀粉糊的热粘、冷粘稳定性和抗剪切性能，使糊的透明度和冻融稳定性增加，当分子取代度大于０．１时，冻融稳定性高达３５次以上。作者还发现，深度羟丙基化木薯淀粉具有特殊的絮凝性质，能溶于冷水，当水溶液加热到一定温度时，溶液发生浑浊，进而絮凝成为胶状物质。胶状物质可从热水中取出，并复溶于冷水，在热水中再絮凝成胶，重复多次。 相似文献
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Graft copolymerization of 2‐(dimethylamino)ethyl methacrylate onto potato starch was carried out in an aqueous medium using a potassium permanganate/sulfuric acid initiation system. The grafting percentage and grafting efficiency were determined as functions of the concentrations of potassium permanganate, sulfuric acid and the monomer, and also polymerization temperature and time. The IR spectrum of the graft copolymer showed the peaks characteristic of the grafted chains. The grafting percentage and grafting efficiency increased and then decreased with increasing the concentrations of potassium permanganate, sulfuric acid, and the monomer, as well as polymerization temperature. The grafting reaction was characterized by an initial fast rate followed a lower rate which leveled off after a certain time. The overall activation energy for the grafting was estimated to be 66.9 kJ/mol. 相似文献
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Alummoottil N. Jyothi Janardhanan Sreekumar Subramoney N. Moorthy Moothandaserry S. Sajeev 《Starch - St?rke》2010,62(1):18-27
Response surface methodology (RSM) was employed for the synthesis of cassava starch‐graft‐poly(acrylamide) using ceric ammonium nitrate as free radical initiator. Concentration of acrylamide, concentration of ceric ammonium nitrate, reaction temperature and duration of reaction were optimized using a 4‐factor 3‐level Box‐Behnken design. The dependent variables were percentage grafting (%G) and grafting efficiency (GE). Second order polynomial relationships were obtained for %G and GE, which explained the main, quadratic and interaction effects of factors. The highest%G and GE obtained were 174.8% and 90.7%, respectively. The optimum values of parameters predicted through RSM were 20 g acrylamide/10 g dry starch, 3.3 g/L ceric ammonium nitrate, 180 min reaction duration and 45ºC temperature with a %G of 190.0. For GE, the predicted levels of factors for the optimum value of 90.8% were 17.5 g acrylamide/10 g dry starch, 4.1 g/L ceric ammonium nitrate, 180 min reaction duration and 55ºC temperature. The graft reaction was confirmed by FTIR analysis, where the absorption bands corresponding to the C=O stretching and N‐H bending of the –CONH2 group were observed. Scanning electron microscopic studies on grafted starches revealed that the granular structure of the starch was affected by the reaction. X‐ray diffraction analysis showed that the crystallinity of starch was decreased as a result of grafting and the reduction was higher for the grafted starches with higher percentage grafting. 相似文献
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Six types of cationic starch derivatives bearing different types of amino groups, i.e., primary, secondary and tertiary or quaternary ammonium salt, were prepared and evaluated as flocculants. Native and hydrolyzed maize starches were used as parent materials for these derivatives. The different factors affecting flocculation were studied. These factors include (a) flocculant dose, (b) pH of the flocculation medium, (c) chemical formula of the flocculant and (d) type of cationic starch, its molecular weight and nitrogen content. 相似文献
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Three types of starch derivatives namely poly(acrylamide)‐starch graft copolymer, carbamoylethylated starch, and starch carbamate were prepared and evaluated as flocculants. Native and hydrolyzed maize starches were used as parent materials for these derivatives. The flocculation was followed by monitoring transmission % and weight removal %. The different factors affecting flocculation were studied. These factors include: (a) flocculant dose, (b) pH of the flocculation medium and (c) starch derivatives type, molar mass and nitrogen content. The flocculation efficiency of the three starch derivatives follows the order: poIy(acryIamide)‐starch graft copoIymer > carbamoylethylated starch > starch carbamate. The flocculation efficiency increases on increasing the nitrogen content and/or decreasing the molar mass of the flocculant. The flocculation efficiency of various flocculants at pH 6 is higher than at pH 8. The poIy(acryIamide)‐ starch graft copoIymer based on H3‐starch has a higher flocculation efficiency than polyacryIamide. 相似文献
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真丝织物阳离子接枝共聚 总被引：7，自引：1，他引：6
研究了阳离子化合物DMC和DMDAAC对真丝织物的接枝共聚。选用过硫酸钾作引发剂,采用轧烘焙的工艺,对影响接枝反应的影响进行了探讨,从而寻求出适宜的工艺条件,并以处理后的织物性能进行了考察。 相似文献
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研究了Mn3 引发下 ,各工艺参数对淀粉丙烯腈接枝共聚反应的影响 .结果表明 :Mn3 配制中 ,Mn2 与Mn7 的摩尔比 (r)对接枝百分率 (G)和单体转化率 (CE)影响最显著 ,反应体系 pH值对接枝效率 (GE)影响最明显 ,而反应温度对它们的影响相对较小 .三者对G、CE和GE的影响均呈二次项关系 ,且它们相互间交互作用不大 .它们的最佳范围分别为 :Mn2 与Mn7 摩尔比为 4左右 ,pH为 1 .4左右 ,温度为 3 8℃左右 .另外 ,与原淀粉相比 ,氧化淀粉和酸解淀粉更易与丙烯腈起接枝共聚反应 ,而可溶性淀粉与丙烯腈反应效果最好 . 相似文献
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以芭蕉芋淀粉为原料,三偏磷酸钠为交联剂,对芭蕉芋淀粉进行交联以制备芭蕉芋交联淀粉。以沉降积为指标,碱性硫酸钠用量、反应时间、反应温度和三偏磷酸钠用量为因素,采用正交实验设计进行交联反应的工艺优化,并对交联淀粉的理化性质和结构进行分析。结果表明:当硫酸钠加入的质量分数为15%,温度35℃,反应时间5 h,三偏磷酸钠添加的质量分数为0.5%时,淀粉的交联度最好;芭蕉芋交联淀粉在拉曼光谱中有明显的磷酸基团吸收峰,具有良好的冻融稳定性、抗老化性、凝胶质构特性和假塑性,可提高体系的弹性与剪切稳定性,为其在食品中应用提供借鉴。 相似文献
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In this study, graft copolymerization of N‐vinylpyrrolidone (N‐VP) onto starch was carried out in an aqueous medium using azobisisobutyronitrile (AIBN) as initiator. The variables affecting the graft copolymerization, such as monomer and initiator concentrations, reaction time and temperature, were thoroughly examined. In general, grafting of N‐vinylpyrrolidone onto starch increased with the increase in time and monomer concentration up to a certain value and then leveled off. Similarly, increase both in initiator concentration and temperature first favored and than impeded the grafting reaction. Optimum conditions established for grafting were as follows: N‐VP = 0.7 M, AIBN = 1.5×10‐3 M, T = 70°C and t = 5 h. Structural changes of the grafted starch were followed by FTIR, intrinsic viscosity and water absorption capacity studies. 相似文献
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Native potato starch has been modified with allylglycidyl ether (AGE) under various reaction conditions including different sodium hydroxide and AGE concentrations, reaction temperatures and times. 1H‐NMR and FT‐IR were used to analyze the products. AGE‐modified starch, with two degrees of substitution (DS), namely DS = 1.3 and DS = 2.3, was synthesized and used for preparation of a new family of crosslinked composites reinforced with various amounts of bleached softwood fibres. Composite premixes of modified starch, wood fibres and ethylene glycol dimethacrylate (EGDA) were cured in a hot press using 2% (w/w) of benzoyl peroxide at 150°C under high pressure for 10 min. The matrix with high degree of substitution exhibited good processability and was easily processed even for the highest fibre contents, up to 70% (w/w). In addition, scanning electron micrographs showed good dispersion and adhesion between the starch matrix with high degree of substitution and fibre. The original poor mechanical properties of the cured modified starch were markedly improved by the addition of wood fibres. In the extractions tests cured high‐DS and low‐DS composite samples showed weight losses in the range of 1 and 15% (w/w), respectively. No unreacted crosslinker ethylene glycol dimethacrylate was detected in the solutes as determined by NMR. 相似文献
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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. 相似文献
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淀粉-丙烯酰胺接枝共聚物具有价廉、无毒、易生物降解等优点,受到研究者的广泛重视.我国在淀粉接枝聚丙烯酰胺的研究方面比较深入,对引发剂影响如硝酸铈铵、过硫酸盐、锰盐、辐射法等进行对比研究,选用不同的接枝共聚工艺方式,优化反应工艺条件,制备了具有不同特性的淀粉接枝聚丙烯酰胺,并把接枝的淀粉应用在废水处理、造纸湿部、吸水剂等多方面.就我国目前几大类引发体系对淀粉接枝聚丙烯酰胺的制备与应用方面进行综述. 相似文献
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Graft polymerization of vinyl acetate (VAc) onto gelatinized and dissolved granular potato starch has been carried out using an initiation system of ceric ammonium nitrate (CAN)/nitric acid (HNO3) at 50°C. The granular starch was dissolved in an aqueous alkaline solution (0.25 M NaOH) for 24 h before graft reaction. The effects of reaction variables, such as the concentrations of acid, monomer, and initiator, on the grafting parameters of prepared starch/VAc copolymers have been investigated in both grafting methods for comparison. Although the scanning electron microscopy (SEM) images showed a rather similar homogeneous structure for dissolved and gelatinized starch, a higher grafting level, especially at lower monomer concentrations, was obtained for the copolymers prepared using the dissolved starch. A larger number of reactive sites uniformly created on the starch molecules led to greater accessibility of the monomer and improved considerably the grafting efficiency in the grafting conditions using the dissolved starch. The effects of the grafting methods on the microstructure, morphology, and thermal stability of the resulting copolymers have been studied by Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy, and thermogravimetric analysis (TGA), respectively. The TGA results showed that the grafting of VAc onto dissolved starch led to the formation of more thermally stable graft copolymers. 相似文献