CAN - KPS体系引发淀粉接枝共聚为絮凝剂的工艺研究

为克服引发剂铈盐较昂贵,工业应用难的缺点,实验采用CAN-KPS复合引发体系引发丙烯腈接枝改性淀粉,采用接枝率和接枝效率作为评价接枝效果的指标,详细研究了接枝工艺及其引发剂浓度、丙烯腈单体的用量和接枝温度对接枝率和接枝效率的影响,结果表明:接枝率达130%以上,接枝效率达90%以上,可较好地代替铈盐引发剂。接枝后对接枝淀粉的结构分析表明:淀粉大分子上已接枝上丙烯腈单体;接枝反应不仅发生在淀粉的无定形区也发生在结晶区,且接枝后接枝淀粉的结晶度有所提高。     

淀粉接枝丙烯酰胺絮凝剂的合成及影响因素

以玉米淀粉和丙烯酰胺为原料,过硫酸铵为引发剂,用水溶液聚合法合成了淀粉接枝丙烯酰胺絮凝剂。研究了反应温度、反应时间和引发剂用量等反应条件对单体转化率、接枝率、接枝效率、絮凝性能的影响。结果表明:在淀粉与丙烯酰胺单体的质量比为1∶2,反应温度为45℃,反应时间为3h,引发剂用量为单体的1.25%时,产物接枝效率、单体转化率、接枝率最高,絮凝性能较优。     

机械活化淀粉与丙烯酰胺反相乳液接枝共聚反应的研究

淀粉接枝共聚物是一种新型功能性材料.研究了经机械活化预处理后的玉米淀粉与丙烯酰胺在反相乳液体系中的接枝共聚反应规律,分别考察了机械活化时间、反应时间、反应温度、油水比、引发剂浓度和淀粉单体比对单体转化率、接枝率和接枝效率的影响.实验结果表明,在本实验考察范围内的最佳反应条件是淀粉活化30 min、反应温度50℃、反应时间2 h、m(单体):m(淀粉)=1.6:1、V(油):V(水)=1.2:1、引发剂浓度1.46 mmol·L-1;在该反应条件下,单体转化率96%,接枝率56.7%,接枝效率85.3%.而原淀粉在类似条件下,单体转化率为72.5%,接枝率和接枝效率分别为46.9%和66.5%.机械活化作用破坏玉米淀粉的结晶区,与丙烯酰胺反应几率增大,有效地提高了玉米淀粉的化学反应活性.     

丙烯腈接枝交联淀粉的制备及应用研究

以玉米交联淀粉为原料,环氧氯丙烷为交联剂,制备了交联接枝玉米淀粉;再以FeSO4-H2O2为引发剂,研究了丙烯腈接枝交联淀粉的制备工艺及其在处理生活污水方面的应用。结果表明,10g玉米交联淀粉、丙烯腈用量10mL、引发剂用量4mL、接枝时间1.5h、反应温度40℃,此条件下接枝率可达83.7%,接枝效率为116.3%,丙烯腈接枝交联淀粉处理过的污水透光率达96.5%。     

丙烯腈接枝淀粉高吸水树脂的制备

以硝酸铈铵为引发剂,在玉米淀粉上接枝丙烯腈制得高吸水树脂,并采用正交实验找出最佳配比和最佳反应条件。最佳配比为:m(淀粉):m(单体)=1:1,m(引发剂):m(单体)=3:100;最佳反应条件为:接枝温度为30℃,接枝时间为90min。     

荻草表面接枝处理对荻草/PE复合材料力学性能的影响

将碱处理过的荻草与丙烯腈单体进行接枝共聚,研究了反应条件对荻草接枝率的影响。采用挤出和注塑工艺制备了荻草/聚乙烯复合材料,并对比分析了荻草的接枝处理对复合材料拉伸性能和弯曲性能的影响。结果表明:在一定条件下,以硝酸铈铵为引发剂,可以有效引发荻草与丙烯腈间的接枝共聚反应,并取得较高的单体转化率和接枝效率;采用接枝后的荻草所制备的木塑复合材料,其力学性能明显改善。     

淀粉接枝共聚动力学研究

以硝酸铈铵为引发剂,研究了MMA、BA、AA和MMA-BA混合单体在木薯淀粉上的接技共聚反应;考察了聚合温度、单体的浓度、种类和配比、引发剂用量等因素对转化率、聚合速率、接枝率和接枝效率的影响。结果表明,随着聚合温度和引发剂用量的上升,接枝效率均上升;单体浓度上升,接枝率、初始聚合速率和最终转化率也上升,但接枝效率则下降;接枝率和接枝效率依MMA>BA>AA的顺序递降,使用MMA—BA混合单体则介于二者之间。     

马铃薯淀粉接枝丙烯腈系涂料的制备及性能研究

以丙烯腈为接枝单体,过硫酸钾为引发剂,对马铃薯进行了接枝改性,并以共聚物乳液为成膜物,与颜填料混合制备成涂料,对各项性能进行测试。并且考察了温度、反应时间、单体配比和引发剂用量对接枝率和接枝效率的影响。     

淀粉接枝丙烯酸聚合型絮凝剂的合成及絮凝性能研究

以可溶性淀粉为主要原料,以丙烯酸为接枝单体,硝酸铈铵和过硫酸钾为复合引发剂,采用溶液聚合的方法对糊化处理后的淀粉进行接枝聚合,合成出环保型淀粉衍生物水处理絮凝剂。通过对接枝聚合反应温度、反应时间、引发剂用量以及丙烯酸单体用量等因素对接枝率影响的研究,确定较佳的接枝产物合成条件：淀粉10g,单体丙烯酸用量10mL,硝酸铈铵和过硫酸钾（摩尔比1：1）复合引发体系用量2mmol,接枝反应温度50℃,接枝反应时间3h,接枝率达到43．2％。利用选煤后的废水对其产品絮凝性能进行实验研究,确定较佳的废水絮凝处理条件。     

以Fe~(2+)-H_2O_2氧化还原体系引发木薯淀粉与醋酸乙烯酯接枝共聚反应研究

研究了以Fe2+-H2O2为引发剂的木薯淀粉与醋酸乙烯酯的接枝共聚反应,并对重要的反应条件进行了讨论。结果表明:当单体与淀粉的质量配比为1.0~2.0,引发剂浓度为1.0 mmol/L,H2O2与Fe2+的摩尔比为2,反应温度为40°C,反应时间为3 h,采用Fe2+→单体→H2O2的加料顺序时,可以得到较高的转化率、接枝率、接枝效率,分别为86.47%、55.30%及31.98%,并探讨Fe2+-H2O2的引发机理。通过Srectrum One红外光谱及电镜对接枝物的结构进行了分析。     

淀粉接枝丙烯腈制备絮凝剂的工艺优化及应用研究

研究了淀粉接枝丙烯腈的各种因素对接枝率和接枝效率的影响。结果表明,接枝改性淀粉絮凝剂的最佳工艺条件:可溶性淀粉与丙烯腈的质量比为1∶3,硝酸铈铵的浓度为6 mg/L,接枝温度为35℃,接枝时间为2 h。在此条件下,接枝率可达172%,接枝效率92%。所制得高分子絮凝剂较无机絮凝剂对较高浓度的有机废水有较好的浊度、COD去除率及沉降速度。     

焦磷酸锰络阴离子引发淀粉与苯乙烯及其二元单体接枝共聚的研究

采用廉价无毒的焦磷酸锰（Ｍｎ＾３＋）络离子作为引发剂，以十二烷基硫酸钠为乳化剂，对淀粉与苯乙烯及二元单体接枝共聚进行了初步探索，研究了单体浓度，引发剂浓度，反应温度及反应时间对接枝反应的影响趋势，发现Ｍｎ＾３＋具有良好的引发效果，接枝效率在６５％～９０％，接枝率可达２００％，对淀粉与Ｓｔ／ＡＮ，Ｓｔ／ＥＡ二元单体接枝共聚的研究表明接枝效率不高。     

Modification of sago starch by graft copolymerization. Effect of reaction conditions on grafting parameters

Graft copolymerization of acrylonitrile onto sago starch was carried out by a free radical initiating process in which the ceric ion (Ce 4+ ) was used as an initiator. The reaction conditions significantly influence the graft copolymerization. The percentage of grafting, grafting efficiency and rate of grafting were all dependent on the concentration of ceric ammonium nitrate (CAN), acrylonitrile (AN), sago starch (AGU, anhydro glucose unit), mineral acid (H 2 SO 4 ) and the reaction temperature and period. The optimum yield was obtained when the concentrations of CAN, AN, AGU and H 2 SO 4 were used at 9.61×10 ?3 , 0.653, 0.152 and 0.187 mol L ?1 , respectively. The optimum temperature and reaction period were 50°C and 90 min, respectively. The rate of graft copolymerization was examined using the experimental results and the reaction mechanism. The polya1crylonitrile grafted sago starch was characterized by using FT-IR spectroscopy, DSC and SEM analysis.     

微波辐射制备淀粉接枝共聚高吸水树脂研究进展？

综述了微波辐射下五种淀粉接枝共聚高吸水树脂的制备研究进展,包括淀粉接枝丙烯腈类高吸水树脂、淀粉接枝丙烯酸类高吸水树脂、淀粉接枝多元单体类高吸水树脂、淀粉系列互穿网络高吸水树脂、无机复合淀粉接枝高吸水树脂等;指出了微波辐射制备淀粉接枝共聚高吸水树脂的研究中,几个需要加强的研究方向：加强理论研究与实践研究的相互促进,开发新型无机矿物复合淀粉接枝共聚高吸水树脂等。     

淀粉接枝共聚高吸水性树脂的研究进展

分别以化学引发法和辐射引发法阐述了淀粉接枝高吸水树脂的研究进展和生产情况。介绍了化学引发接枝聚合淀粉接枝丙烯腈类树脂、淀粉接枝丙烯酸类树脂、淀粉接枝多元单体类树脂、复合型淀粉接枝脂类树脂的研究现状,对化学引发的主要影响因素进行了评述。讨论了辐射引发淀粉接枝高吸水树脂中所应用的微波辐射引发、紫外光辐射引发和γ射线辐射引发的技术优势和应用现状。指出今后淀粉类高吸水性树脂的研究应该向多元接枝共聚、制备复合型树脂和抗盐性树脂、微波固相合成、简单工艺、高效引发剂和加强理论基础研究方向发展。     

Graft copolymers of starch–polyacrylonitrile prepared by ferrous ion–hydrogen peroxide initiation

The effect of concentration, reactant ratios, temperature, and starch pretreatment on grafting of acrylonitrile onto starch were studied. Grafting was efficient at high concentrations (8–12% starch) when granular starch was used. The molecular weights for grafted polyacrylonitrile (PAN) were higher when gelatinized starch was used, but grafting efficiencies (grafted PAN/total PAN) were much lower. The molecular weight of the grafted side chain increased with increased concentration of reactants. The grafting frequency was highest when the reaction mixture was kept at 5°C and decreased with increased swelling of the starch. The starch–polyacrylonitrile graft copolymers were saponified and dried to give products which absorbed 75–440 ml H₂O per gram and 20–70 ml synthetic urine per gram.     

Optimization of synthesis and characterization of cassava starch‐graft‐poly(acrylonitrile) using response surface methodology

Graft copolymerization of poly(acrylonitrile) onto cassava starch was carried out with potassium persulphate (PPS) as the free radical initiator using a response surface Box–Behnken design. Different levels of monomer concentration, initiator concentration, and temperature were used, and regression models were generated in terms of these factors, which can be used to predict the grafting level and efficiency at a given level of the factors. The grafted starches were characterized by FTIR, XRD, and SEM analyses and determination of %grafting (%G), N‐content, thermal properties, water and saline solution retention, and rheological properties. Under the conditions used, %G was found to depend only on the temperature used for the reaction. The maximum %G of 120.1 was obtained for the sample synthesized under the following conditions: weight of AN = 0.753 mol/10 g starch, weight of PPS = 0.284 g and temperature = 55°C, and the grafting efficiency was 30.03%. The absorption bands at 2243 cm^?1 for the nitrile group (? CN) in the FTIR spectra of the products confirmed the grafting reaction. There was a decrease in crystallinity and disappearance of the granular structure after grafting of the starch. The melting temperatures of the graft copolymers determined by differential scanning calorimetry analysis were higher than that of the native starch. The grafted starches exhibited very high thermal stability as observed from the thermogravimetric analysis. The superabsorbent polymer prepared from the grafted starch by alkali saponification exhibited a maximum water absorbency of 636 g/g. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

双氧水引发下淀粉／丙烯腈接枝聚合物的制备与分析

以淀粉为原料,在双氧水的引发下,与丙烯腈进行接枝反应制备淀粉接枝聚合物。考察了温度、时间、引发剂浓度、接枝剂浓度等单因素对接枝率的影响。对影响接枝反应的各种因素,如反应物的用量、反应时间、引发剂浓度等进行了深入细致的分析探讨,由正交试验确定出双氧水为引发剂,进行淀粉接枝反应的最佳工艺条件为：反应温度85℃,反应时间3h,料液比1：100,引发剂浓度17．143mmoL／L,丙烯腈浓度0．114mmol／L。     

Carboxyl-containing starch graft polymer: Preparation and use in heavy metal removal

Water-insoluble carboxyl-containing starches were prepared by grafting acrylonitrile onto a highly crosslinked starch followed by base saponification to convert nitrile groups into a mixture of carboxamide and carboxylate groups. Ceric ammonium nitrate or ferrous sulfate–hydrogen peroxide was used to initiate graft polymerization of acrylonitrile. The isolated products were evaluated for the removal of Cd²⁺, Cu²⁺, and Pb²⁺ from aqueous solution.