两性淀粉接枝共聚物的就地制备和性质

糊化淀粉经阳离子试剂醚化后再直接与丙烯酸钠(AA-Na)/丙烯酰胺(AM)接枝共聚,制得具有两性的淀粉接枝共聚物。并对淀粉的阳离子试剂醚化、淀粉与AA-Na/AM接枝共聚的接枝率、单体转化率、接枝效率及淀粉的糊化方式对产物性能的影响进行了研究。为工厂就地生产和应用两性淀粉接枝共聚物提供技术依据。     

阳离子淀粉-壳聚糖-丙烯酰胺的接枝共聚研究

以硝酸铈铵为引发剂,合成阳离子淀粉(CS)-壳聚糖(CTS)-丙烯酰胺(AM)接枝共聚物,讨论了反应温度、引发剂浓度、单体用量、反应时间以及壳聚糖用量对接枝共聚反应的影响。结果表明:淀粉中葡萄糖环浓度(cAGU)为0.20 mol/L,mCTS/mCS=1/6,cAM=1.0mol/L,cCe4 =5 mmol/L,反应温度60℃,反应时间3 h时,转化率和接枝效率可分别达到88%和92%以上;转化率随mCTS/mCS增大而增大,接枝效率则随着CTS用量增大降低,CTS的存在使AM均聚的几率增大。     

淀粉基阳离子絮凝剂的研制及性能测试

用可溶性淀粉为原料,通过接枝改性合成了一种淀粉基阳离子絮凝剂(MSF),其最佳制备工艺条件为:淀粉与丙烯酰胺的质量比为1:2,引发剂用量为0.6 g,反应温度为50 ℃,接枝时间为3.5 h;阳离子化条件为:甲醛和二甲胺摩尔比为1.0:1.4,反应时间2.5 h,反应温度50 ℃.产物结构经FTIR证实.用其处理番茄废水后,废水的透光率提高了78.2%、TOC下降了22.5%、COD下降了37.25%,结果表明该产品对高浓度有机废水的絮凝性能优于聚丙烯酰胺高分子絮凝剂(PAM).     

淀粉接枝聚丙烯酰胺阳离子絮凝剂的合成及应用——推荐一个高分子化学综合实验

介绍一个综合化学实验。实验通过淀粉与丙烯酰胺的接枝聚合反应和阳离子化改性,合成了一种新型淀粉接枝聚丙烯酰胺阳离子高分子絮凝剂,进行了结构表征,以人工模拟染料废水和重金属离子废水为实验对象,探究了合成的聚丙烯酰胺、淀粉接枝聚丙烯酰胺和淀粉接枝聚丙烯酰胺阳离子絮凝剂在废水净化中的应用。本实验理论与实践相结合,有助于激发学生的学习兴趣,培养学生的学科交叉融合思维和分析解决问题的能力。     

CAN引发S—DMDAAC—AM接枝共聚的研究

以硝酸铈铵(CAN)为引发剂,以淀粉(S)、二甲基二烯丙基氯化铵(DMDAAC)和丙烯酰胺(AM)为原料,通过反相乳液聚合,合成接枝共聚物。研究了加料顺序、引发剂浓度、单体与淀粉配比、油水体积比、乳化剂用量等因素对产品性能的影响。并用IR和1H-NMR对接枝产物进行了分析表征。     

氧化锌催化淀粉/乳酸接枝共聚物的制备与表征

以氧化锌为催化剂,采用原位聚合法制备了淀粉/乳酸接枝共聚物。由FT-IR、1H NMR、XRD和SEM对接枝产物进行了表征,且讨论了反应温度、淀粉与乳酸质量比、催化剂用量和反应时间对淀粉接枝率的影响,结果表明,当反应温度为95℃,淀粉与乳酸质量比为1∶5,催化剂用量为乳酸质量的1.0%,反应时间11 h时,产物的接枝率可达到14.20%。     

阳离子聚丙烯酸酯乳液的制备及其在造纸中的应用

以缩水甘油醚三甲基氯化铵(GTA)和丙烯酸为原料,合成了阳离子丙烯酸酯单体,研究了反应物配比、温度、时间、及催化剂用量对产物酯化率的影响,确定了产物最优合成工艺为:异丙醇作反应溶剂,n(丙烯酸)∶n(GTA)=1.1∶1,反应温度70℃,反应时间6h,此条件下酯化率78%,产物收率86%.产物结构通过红外光谱得以证实.该单体经种子乳液聚合得到阳离子聚丙烯酸酯乳液,与氧化淀粉复配后制备的阳离子表面施胶剂对提高纸张的强度具有明显作用.     

双变性淀粉吸附剂的合成及吸附性能研究

以环氧氯丙烷、交联化淀粉和丙烯腈为原料,水为溶剂,硝酸铈铵为引发剂,通过接枝反应合成了双变性淀粉吸附剂。其最佳制备工艺条件是交联化淀粉2g,硝酸铈铵浓度0.004mol/L,丙烯腈浓度0.3774mol/L,接枝温度35℃,接枝时间240min,料液比1:10(W/V)。对制得的双变性淀粉进行金属离子吸附性能评价,发现Cr6 吸附时使溶液处于中性或微酸性环境下,Cu2 吸附时使溶液处于弱碱性环境下,Cu2 的吸附率达到86.3%,Cr6 吸附率达78.2%,Cu2 吸附效果大于Cr6 。     

淀粉-磺甲基化聚丙烯酰胺接枝共聚物的合成及性能

用淀粉-聚丙烯酰胺接枝共聚物(S-g-PAM)同多聚甲醛及亚硫酸钠反应,合成了淀粉-磺甲基化聚丙烯酰胺接枝共聚物(S-g-SPAM)。该磺化物的水溶液在试验浓度范围内(0.1～1.0％),为假塑性流体,对高岭土悬浮液的絮凝,由沉降速度,上层清液相对吸光度可知,S-g-SPAM(接枝链分子量为1.03×10⁵,磺甲基化度30％)的絮凝能力优于相应的未磺化的S-g-PAM,也比聚丙烯酰胺(分子量2.5×10⁶)强。     

复合淀粉-丙烯酰胺聚合物在秦始皇帝陵和汉阳陵土遗址脱盐中的应用

制备了一种复合淀粉接枝丙烯酰胺高分子聚合物(St-PAM).经红外光谱、扫描电子显微镜等方法表征发现,淀粉与丙烯酰胺接枝共聚形成具有多层片状、尖锐断面及多重孔道的大比表面积的聚合物.同时,吸水性能测试表明其具有良好的吸水耐盐性能.将材料应用于秦始皇帝陵K9901陪葬坑及汉阳陵地下遗址进行脱盐示范,结果表明,吸水脱盐材料对试验区域表面土层主要成盐离子Ca^(2+)和SO_4^(2-)的移除率分别达到70%和90%左右,对含量较少的其他盐类离子,如Na^+、NO_3^-等也有明显效果.     

Application of a new family of amphoteric cellulose-based graft copolymers as drilling-mud additives

A new family of amphoteric cellulose-based graft copolymers (CGADs), which were prepared by grafting acrylamide and dimethylaminoethyl methacrylate onto sodium carboxymethyl cellulose, have been investigated for their properties as multifunctional drilling-mud additives with respect to shale inhibition, rheological control and filtrate-loss control. For the CGADs investigated, the shale-inhibition ability improves but the filtration-control ability weakens with increasing content of cationic groups. An increase in the concentration of CGADs results in better inhibition and viscosity-building as well as lower fluid loss. The pH of the medium has an effect on the inhibitive property. A comparative study among CGADs and some commercial polymeric drilling-mud additives was also carried out. Received: 24 February 1999 Accepted in revised form: 10 May 1999     

MANGANESE (IV)-INITIATED GRAFTING OF TRIMETHYLALLYLAMMONIUM CHLORIDE ONTO CARBOXYMETHYLCELLULOSE

Graft copolymerization of cationic monomer trimethylallylammonium chloride onto anionic carboxymethylcellulose has been investigated in aqueous medium using potassium permanganate/sulphuric acid redox system as initiator, involving the identification of grafting, the mechanism for grafting and various factors affecting grafting. The prepared cellulosic copolymers with amphoteric functional groups have been found to be effective to retard the hydration of clay minerals, showing a potential use as new clay-hydration suppressant for oilfields.     

The adsorption of cationic and amphoteric copolymers on glass surfaces: zeta potential measurements,adsorption isotherm determination,and FT Raman characterization

The adsorption of cationic and amphoteric copolymers onto controlled pore glass (CPG) powders has been studied by measurement of the powder particle zeta (zeta) potential, by determination of the adsorption isotherm, and by FT Raman measurements of the polymer-coated powder. The cationic polymers consisted chiefly of homopolymers of dimethyldiallylammonium chloride (DMDAAC) or copolymers of DMDAAC and acrylamide. The amphoteric polymers studied included copolymers of DMDAAC and acrylic acid. The comonomer ratio was varied to explore the dependence of cationic charge density on the extent and effect of adsorption. Both types of polymers adsorb onto the anionic glass surface via an ion-exchange mechanism. Consequently, a correspondingly higher mass of a low-charge-density copolymer adsorbs than of a cationic homopolymer. The presence of the anionic portion in the amphoteric polymers does not significantly alter this picture. The zeta potential, however, reflects the overall nature of the polymer. Cationic polymers effectively neutralize the glass surface, while amphoteric polymers leave the zeta potential net negative. Adsorption isotherms, determined via the depletion technique using colloidal titration, were used to "calibrate" a FT Raman method. The latter was used to determined the amount of adsorbed polymer under solution conditions in which colloidal titration could not be performed.     

A study of cationic glucomannan as a paper strength agent

In this paper, konjac glucomannan was cationized by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (a kind of cationic reagent) as a paper strength agent. The effects of dosage of cationic reagent, cationization time, cationization temperature and the pH of papermaking on paper properties were analyzed. The results showed that when 1% cationic glucomannan (the cationization temperature was 70°C, dosage of cationic reagent was 20% and cationization time was 5 h) was added, tensile index, burst index and folding endurance of the paper were improved by 11.0%, 13.2%, 72.0%, respectively, compared with the control. The results of SEM analysis, FTIR analysis, and elemental analysis illustrated that the addition of paper strengthening agent make fibers combined more closely, and further lead to the increase of paper strength properties.     

Synthesis of Amphiphilic Graft Copolymers with Poly(2‐methyl‐2‐oxazoline) Side Chains and a Backbone Containing Chloromethylstyrene and Methyl Methacrylate

New amphiphilic graft copolymers were synthesized by means of a cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline initiated with a statistical copolymer of methyl methacrylate and chloromethylstyrene. The synthesis was carried out in benzonitrile at 110°C. The grafting reaction was quantitative and the yield of grafting was more than 90%percent;. The graft copolymers were characterized by means of NMR, FT‐IR, and UV‐VIS spectroscopy, as well as elemental analysis and viscosity measurements of their aqueous solutions. The graft copolymers revealed amphiphilic properties and evidence for the formation of micelles and molecular aggregates in aqueous solution. Graft copolymers with relatively short lateral chains are soluble in methanol but insoluble in water, while the copolymers with longer lateral chains are soluble in both methanol and water.     

Effect of microfibrillated cellulose and fines on the drainage of kraft pulp suspension and paper strength

Different types of microfibrillated cellulose (MFC) and fines suspensions were produced, characterized, and then added to a papermaking pulp suspension. High and medium molar mass cationic polyelectrolytes were used as fixatives. The drainage behavior of the pulp suspensions with additives were evaluated against the strength properties of hand sheets made thereof. The effects of salt concentration, pH, fixative type, dosage and type of fibrillar material on drainage were examined. All the MFC and fines samples produced had clearly different properties due to their dissimilar production methods, and they also introduced specific responses on the measured drainage and paper strength. Generally, the addition of MFC decreased the drainage rate of pulp suspension and increased the strength of paper. However, it was shown that by optimum selection of materials and process conditions an enhancement of the strength properties could be achieved without simultaneously deteriorating the drainage.     

Target grafting of poly(2-(dimethylamino)ethyl methacrylate) to biodegradable block copolymers

A series of copolymers composed of methoxy poly(ethylene glycol) and a hydrophobic block of poly(ɛ-caprolactone-co-propargyl carbonate) grafted with poly(2-[dimethylamino]ethyl methacrylate) was synthesized by combining ring opening polymerization, azide-alkyne click reaction, and atom transfer radical polymerization (ATRP). Well-defined copolymers with a target composition and a tailored structure were achieved via the grafting from approach by using a single catalytic system for both click reaction and ATRP. Kinetic studies demonstrated the controlled/living character of the employed polymerization methods. The thermal properties and self-assembly in aqueous medium of the graft copolymers were dependent on their composition. The resulting polymeric materials showed low cytotoxicity toward L929 cells, demonstrating their potential for biomedical applications. This type of materials containing cationic side chains tethered to biocompatible and biodegradable segments could be the basis for promising candidates as drug and gene delivery systems.     

Interactions between cellulose nanofibers and retention systems in flocculation of recycled fibers

Although the positive effect that cellulose nanofibers (CNF) can have on paper strength is known, their effect on flocculation during papermaking is not well understood, and most relevant studies have been carried out in presence of only cationic starch. Flocculation is the key to ensuring retention of fibers, fines, and fillers, and furthermore floc properties have a great influence on paper quality. The aim of this research is to study the interactions between CNF and flocculants by assessing the effect of two types of CNF, from eucalyptus and corn, on the flocculation process induced by three different retention systems [a dual system, polyvinylamine (PVA), and cationic starch as reference]. The results showed that CNF interacted with the flocculants in different ways, affecting flocculation efficiency and floc properties. In general, addition of CNF increased floc stability and minimized overdosing effects. Moreover, presence of CNF increased floc size for given PVA dose; therefore, CNF addition could contribute to improve the wet end in the paper machine if combined with the optimal flocculant and dose.     

Preparation and Characterization of Poly(Lactic Acid)-g-Maleic Anhydride + Starch Blends

Poly(lactic acid) (PLA) and starch copolymers are obtained by reactive blending - varying the starch compositions from 0 to 60%. PLA is functionalized with maleic anhydride (MA), obtaining PLA-g-MA copolymers using dicumyl peroxide as an initiator of grafting in order to improve the compatibility and interfacial adhesion between the constituents. PLA + starch blends without a compatibilizer do not have sufficient interfacial adhesion. Decomposition temperature of PLA is not affected by grafting. Glass transition temperatures and dynamic mechanical properties are affected since MA has a plasticizing effect. Along with an increasing starch content friction decreases while wear loss volume in pin-on-disk tribometry has a minimum at nominal 15% wt. starch but increases at higher starch concentrations. The residual depth in scratching and sliding wear testing has a maximum at 15% starch; there is a minimum of storage modulus E′ determined in dynamic mechanical testing at the same concentration. Microhardness results also reflect the plasticization by MA.     

紫外分光光度法测定含吡啶盐型共聚物的阳离子度

报道了用紫外分光光度法在268nm处定量测定含吡啶环的高分子共聚物中吡啶环的含量,据此计算出该共聚物的阳离子度。实验结果表明:共聚物的阳离子度随着疏水碳链的增长而逐渐减小;同时与高聚物的阳离子度测定的经典方法———AgNO3法进行了比较,结果表明:对于含有吡啶环的高聚物的阳离子度测定,对于含有共轭体系的高聚物的分析如阳离子度的测定和对具有特征紫外吸收体系的含量测定等,紫外分光光度法是一种简便、快速、准确而有效的实验方法。