马铃薯淀粉与醋酸乙烯酯接枝聚合影响因素的研究

以马铃薯淀粉为接枝骨架,过硫酸铵为引发剂,醋酸乙烯酯(VAc)为接枝单体进行接枝共聚。考察了不同引发剂浓度、反应温度、反应时间、单体配比、淀粉浓度对单体转化率、接枝率及接枝效率的影响,确定最佳工艺条件为:引发剂浓度18 mmol/L,反应温度60℃,反应时间3.5 h,单体配比2.5:1,淀粉浓度5%。并通过扫描电镜,X射线衍射,傅里叶红外光谱对淀粉接枝共聚物进行分析,结果表明:淀粉接枝共聚后,淀粉的微观形貌已经改变,结晶度降低且醋酸乙烯酯成功接枝在马铃薯淀粉上。     

乳液聚合法和微波法制备淀粉与苯乙烯接枝共聚物比较

分别采用乳液聚合法和微波法制备淀粉与苯乙烯接枝共聚物,对其接枝参数进行比较,并利用红外光谱、扫描电子显微镜等测试手段对接枝共聚物微观结构进行分析比较,确定乳液聚合法和微波法制备淀粉与苯乙烯接枝共聚物为同一物质;通过比较得出乳液聚合法接枝百分率和接枝效率高于微波法,而微波法节约时间和能源。     

Gamma Radiation-Induced Graft Copolymerization of Acrylonitrile Onto Sodium Salt of Partially Carboxymethylated Amylose

The graft copolymerization of acrylonitrile onto Sodium salt of Partially Carboxymethylated Amylose (Na-PCMA, DA=0.313) in aqueous and in water: methanol mixed solvents system has been studied using gamma rays from Co⁶⁰ source as a means of initiation by the mutual method. The optimum condition for affording maximum percentage of grafting of acrylonitrile onto Na-PCMA has been obtained by varying different reaction parameters such as total dose, monomer concentration, amount of water and composition of solvents system. The mechanism of grafting has been postulated. The resulting graft copolymer has been characterized by chemical, spectroscopic, thermogravimetric and scanning electron microscopic methods.     

Response Surface Methodology for the Optimization and Characterization of Cassava Starch‐graft‐Poly(acrylamide)

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.     

Graft Copolymerization Onto Starch. 3: Grafting of Acrylamide Using Ceric Ion Initiation and Preparation of Its Hydrogels

The grafting of acrylamide (AM) onto maize starch in aqueous medium initiated by ceric ammonium nitrate (CAN) has been studied gravimetrically under nitrogen atmosphere. The effect of concentration of monomer and initiator, polymerization time and reaction temperature has been studied in terms of efficiency of grafting (%GE) and percentage Add-on (%Add-on). The %GE was found to decrease with increase in monomer concentration, but the reverse trend was obtained on increasing the polymerization time and temperature. The maximum %GE was obtained at 45°C when polymerization was carried out for 180 min using [CAN] = 0.004 mol/L and [AM] = 0.141 mol/L in 100 mL of distilled water with 2 g of starch. These graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. The graft copolymers showed enhanced thermal stability than pure starch. Hydrogels were prepared by grafting AM onto gelatinized maize starch followed by saponification of these graft copolymers with NaOH. The maximum water absorption obtained was 170 g/g.     

Pasting,swelling and solubility properties of UV initiated starch-graft-poly(AA)

UV-initiated graft copolymerization of sago starch with acrylic acid (AA) at low level (2.5%, 5%, 7.5% and 10% w/w) was investigated. The UV curing technique and procedure was found to successfully produce starch-graft-poly(acrylic acid) [S-g-poly(AA)]. The carboxyl group content was found to increase with increasing % of monomer. Rapid visco-analyzer (RVA) pasting profile, swelling and solubility of the samples were studied. UV irradiation of sago starch (control) results in high pasting temperature, high peak viscosity and high setback, besides retarding swelling and solubility as compared to the native untreated starch (p<0.05). Pasting temperature was decreased after grafting as compared to the control. S-g-poly(AA) showed higher peak viscosity, peak time and setback than native untreated starch (p<0.05). Breakdown was retarded at 2.5% S-g-poly(AA) but increased at 10%. S-g-poly(AA) exhibited lower swelling power and solubility than the native sample (p<0.05).     

Microwave assisted synthesis and characterization of Sago starch‐g‐acrylamide

In the present investigation, sago starch was modified through microwave assisted chemical synthesis using acrylamide as grafting monomer. Grafted copolymer was characterized by fourier transform infra red spectroscopy (FTIR), scanning electron microscopy (SEM), X‐ray powder diffractometer (XRD) and thermo gravimetric analysis (TGA). Swelling study was also performed at various temperatures to access its suitability in diverse industrial application. The optimum reaction conditions were found as follows: starch, 1 g; acrylamide (AMD), 5 g; microwave power, 600 W, reaction time, 3 h. Grafting on the starch backbone confirmed by FTIR spectral analysis, while XRD confirmed formation of more crystalline structure after AMD grafting. TGA analysis showed formation of more thermostable copolymer after grafting, while swelling study proved its suitability for various industrial applications due to its extensive swelling at higher temperatures.     

Synthesis,characterization and swelling behaviour of superabsorbent polymers from cassava starch‐graft‐poly(acrylamide)

Superabsorbent polymers (SAPs) were prepared from cassava starch by graft copolymerization of acrylamide on to starch using ceric ammonium nitrate (CAN) as free radical initiator, followed by alkali saponification. The reaction parameters such as concentration of acrylamide, concentration of CAN, temperature, and duration of polymerization reaction were optimized for maximum water absorbency using a 4‐factor 3‐level Box‐Behnken design. The highest values of percentage grafting and absorbency obtained were 174.8% and 425.2 g/g, respectively. The polymers were characterized by determination of grafting efficiency, N‐content, acrylamide content, FTIR analysis, SEM and XRD analyses. Thermogravimetric analysis (TG) showed that the SAP has higher thermal stability. The rate of water absorbency and the swelling behaviour of the SAP under different conditions of pH, and different salts were determined. The de‐swelling pattern of the hydrogels over different time durations was also determined.     

研究淀粉与丙烯酸甲酯在微波加热时的接枝共聚反应

淀粉与乙烯基单体接枝共聚物是淀粉化学改性的重要方法,该聚合物具有合成和天然高分子的优良性能,在生物降解塑料中有很好应用。以玉米淀粉为原料、丙烯酸甲酯为单体、硝酸铈铵为引发剂,引发接枝共聚反应,探讨了引发剂浓度、单体浓度、反应温度、反应时间对接枝共聚反应的影响规律,用红外光谱来测定反应产物的结构。实验结果表明:丙烯酸甲酯的浓度为1.16mol/L、引发剂硝酸铈铵的浓度为3.10mmol/L、反应时间在6min,接枝百分率、接枝效率达到最佳。     

低温等离子体引发聚丙烯薄膜气相接枝丙烯酸

利用等离子体处理聚丙烯(PP)薄膜后在气相环境中引发丙烯酸在其表面接枝聚合.实验结果表明,接枝处理15 min即可使PP薄膜的接触角从97°降至32°,说明亲水性大幅提高.红外光谱和扫描电镜分析表明,丙烯酸已接枝在PP薄膜表面,生成了众多l～2 μm的凸起物.经l0 min沸水处理后,接枝PP薄膜的水接触角无明显增加,...     

Mn^3＋引发制得的淀粉与丙烯腈接枝共聚物中的交联键

通过淀粉丙烯腈接枝共聚物（ＳＰＡＮ）在二甲亚砜（ＤＭＳＯ）溶剂中溶解度变化情况推断，Ｍｎ＾３＋引发下，淀粉与丙烯腈接枝共聚反应生成的ＳＰＡＮ分子中存在有交联键，且这种交联键是由接枝共聚反应过程中共聚物自由基偶合反应形成的。     

季铵—磺酸型淀粉基高分子聚合物的合成及应用

研究了以淀粉为基材,以丙烯酰胺(AM)、丙烯酰氧乙基三甲基氯化铵(AAC)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为聚合单体,采用溶液聚合技术合成两性接枝共聚物的方法。考察了引发剂用量、反应温度、反应时间、溶解助剂用量、络合剂用量等因素对单体转化率、接枝率、产物特性粘数及溶解性的影响。最佳反应工艺条件为:引发剂质量浓度为0.1%,m(单体)∶m(淀粉)=7∶3,反应温度50℃,反应时间4h。所得产物的接枝率达217.92%、转化率达93.74%、特性粘数达543.31ml/g。该聚合物用于处理油田污水效果好于聚丙烯酰胺类絮凝剂。     

淀粉接枝共聚物生物降解塑料的研究

以玉米淀粉为原料，进行了淀粉化学改性，偶联，淀粉接枝共聚反应动力学的研究和生物降解塑料的工艺，配方及产品应用研究，并对淀粉接枝共聚物进行ＳＥＭ观察，显微熔点测定，生物降解试验和ＡＳＴＭ试验。建立了淀粉接枝共聚反应系统，研制成功的淀粉接枝共聚物生物降解塑料综合性能达到国际同类产品水平。     

Effect of acid–methanol treatment on the molecular structure and physicochemical properties of lentil (Lens culinaris Medik) starch

The effect of acid–methanol treatment using 0.36% HCl in methanol at 25 °C for 4–216 h on molecular structure and physicochemical properties of lentil starch was investigated. The recoveries for modified starch granules were quite high (91.9–95.6%). Upon modification, the starch granules showed formation of cavities, surface roughness and development of protuberances. The solubility of lentil starch increased, while swelling power, pasting viscosity and gel strength decreased with increase in treatment duration. These changes were found to be due to preferential degradation of amylose and amylopectin long chains in acid–alcohol treatment, which was confirmed by studies conducted on high-performance size-exclusion chromatography (HPSEC). Data obtained from HPSEC was also used to develop an exponential model to illustrate the degradation kinetics of acid–methanol-treated lentil starch.     

Cotton Yarn Sizing by Acrylamide Grafted Starch Copolymer

Synthesis and characterization of copolymer obtained by grafting acrylamide onto hydrolyzed potato starch and its application in cotton yarn sizing were presented in this work. Some process parameters of starch hydrolysis and grafting, like as hydrolysis yield, grafting yield, grafting percentage, graft efficiency, and monomer to polymer conversion were determinated. Molar mass values of hydrolyzed starch and copolymer samples are located in a narrow range of 1 × 10⁵ to 1 × 10⁷ and 1 × 10² to 1 × 10⁴. Grafted hydrolyzed starch, as a sizing agent, gives better results than nongrafted, particularly in terms of sizing uniformity, yarn mechanical parameters, and easier removal in subsequent desizing process.     

Grafting of 2‐(Dimethylamino)ethyl Methacrylate onto Potato Starch Using Potassium Permanganate/Sulfuric Acid Initiation System

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.     

Synthesis and Thermal Degradation of a Novel Starch Graft Copolymer Incorporating a Sulfobetaine Zwitterionic Monomer

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.     

接枝淀粉理化特性对其上浆性能的影响

为研究接枝淀粉理化特性与其浆用性能的关联,通过微波辅助法将阳离子淀粉与丙烯酰胺、甲基丙烯酸-β-羟乙酯和丙烯酸丁酯接枝共聚,制备出不同接枝率（GR）的接枝阳离子淀粉（GCS）,通过FT-IR和XRD表征产物结构。研究了GCS的理化特性与浆纱性能。结果表明,在一定接枝率范围内,GCS的理化性能改善,表现为水合能力、流变性能增强,抗老化性、透明度提高,而过高的接枝率会导致淀粉理化性能恶化。GCS浆纱性能随接枝率增大而提高,当接枝率为13.58%时,浆纱断裂强力、减伸率和耐磨性达到最优值,随着接枝率进一步增大,浆纱性能指标下降。研究结果还表明接枝淀粉理化特性的改善与其浆用性能的提高密切相关。     

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.     

低取代度阳离子淀粉-丙烯酰胺接枝共聚物的制备及应用

以低取代度的阳离子淀粉为原料,硝酸铈铵为引发剂,制备了低取代度阳离子淀粉-丙烯酰胺接枝共聚物。研究了丙烯酰胺与阳离子淀粉质量比、反应温度、反应时间和引发剂浓度对接枝率和接枝效率的影响。结果表明:接枝率和接枝效率最高的条件为:m(丙烯酰胺)∶m(阳离子淀粉)=2.5∶1,反应温度为55℃,反应时间为3 h,c(引发剂)=2 mmol/L。将合成的聚合物用于纸张增强,当低取代度阳离子淀粉-丙烯酰胺接枝共聚物的用量为1.0%时,对纸张的增强效果最好,可使纸张抗张指数增加23.0%,撕裂指数增加12.7%,耐破指数增加63.7%,耐折度增加115.1%。