Preparation of superabsorbent by graft copolymerization of acrylic acid onto corn starch using K_2S_2O_8 and rare earths as initiators

K2 S2 O8 and rare earths （RE） were used as initiators to prepare superabsorbents by graft copolymerization of acrylic acid （ AA ） onto corn starch. The effects of monomer concentration, initiator K2 S2 O8 concentration, cross-linker concentration, reaction temperature and the concentration ratio of RE and K2 S2O8 on the graft copolymerization were studied in terms of the water absorption capacity of superabsorbents. Results indicate that the optimum conditions obtained for the grafting of AA onto 5g starch are as follows： AA of 75. 773 g/L, K2S20s of 0. 437 g/L, RE of 0. 874 g/L, cross-linker of 0. 381 g/L and temperature of 70 ℃. The maximum water absorption capacity obtained is 740 g/g. The new method of graft polymerization is easily proceeded and controlled. The graft copolymers were characterized by infra-red spectroscopy, scanning electron microscopy and TG. Results characterized by IR and SEM give strong evidence for grafting of AA onto corn starch, and those characterized by TG reveal that the grafting of AA improves the theimostability of corn starch.

Effect of Starch/Polylactic Acid Ratio on the Interdependence of Two-Phase and the Properties of Composites

Starch/polylactic acid(PLA) composites were prepared by melt extrusion, with corn starch and PLA as raw materials, glycerol as the plasticizer. Effects of starch/PLA ratio on the interdependence of two-phase and other properties of the composites were studied. The combination of results of TGA with SEM indicated that the interdependence between starch and PLA was increased gradually as the starch/PLA ratio reduced. DSC results showed that the glass transition temperature(Tg), melting temperature(Tm) and degree of crystallinity of PLA in composites were increased gradually, whereas the cold crystallization temperature(Tc) was gradually decreased as the starch/PLA ratio reduced. The rheological properties of composites were closely related with the interdependence of two-phase, with reducing starch/PLA proportion, the interdependence was increased, and then the strain for storage modulus was firstl reduced and then gradually increased. Frequency scanning showed that the storage modulus and complex viscosity were decreased with reducing starch content. As the starch/PLA ratio reduced, the matrix phase PLA was increased, so that the strength of composites was increased gradually, whereas water absorption rate was decreased gradually.

The Optimized Synthesis of Starch-g-Lactic Acid Copolymer with High Grafting Degree Catalyzed by Sulfuric Acid

The starch-g-lactic acid copolymer was synthesized with catalysis of sulfuric acid by onestep process, and the structure of starch-g-lactic acid copolymer was characterized by means of IR, 13C-NMR, HMBC, XRD, and SEM. The experimental results show that the maximum grafting degree of starch can reach 75% when the starch-g-lactic acid copolymer is activated at 80 ℃ for 2 h and reacted with lactic acid at 90 ℃ for 4 h in vacuum.

聚乳酸改性糯玉米淀粉的制备及表征

以糯玉米淀粉为原料、异辛酸亚锡为催化剂,在丙交酯熔融体系中制备了聚乳酸改性糯玉米淀粉。建立了聚乳酸改性糯玉米淀粉取代度的^(1)HNMR测试方法,以取代度为响应值,反应时间、反应温度、丙交酯添加量为考察因素,通过单因素和响应面实验优化了聚乳酸改性糯玉米淀粉的合成工艺,得到最优工艺为:反应时间12.46 h,反应温度111.75℃,丙交酯添加量为淀粉质量的258%,预测最大取代度为0.0253,通过实际操作条件调整后实际取代度为0.0238。对最优条件下制备的聚乳酸改性淀粉进行了系列表征,证实聚乳酸改性糯玉米淀粉的颗粒结构没有被完全破坏,晶型、相对分子质量等性能优于溶剂法传统技术制备的聚乳酸改性糯玉米淀粉。

制备工艺对高直链玉米淀粉—硬脂酸复合物性质的影响

[目的]优化高抗性淀粉(RS)含量的淀粉—脂质复合物制备工艺,探究工艺参数对复合物抗消化性的影响。[方法]采用单因素试验和正交设计研究了高直链玉米淀粉(HA)预处理及其与硬脂酸(SA)络合过程中温度和时间参数对复合物RS含量的影响,分析最优工艺制备的HA-SA复合物的理化性质、抗消化性及水合特性。[结果]在糊化温区继续升高预处理温度、延长预处理时间、络合温度高于75℃均导致RS含量显著降低(P<0.05);HA-SA复合物最优制备工艺为:HA经85℃的退火温度预处理12 h后,在75℃与SA络合90 min;所制备的HA-SA具有V型晶体特征、完整的淀粉颗粒,为Ⅰ型淀粉—脂质复合物;与HA相比,其热稳定性、抗消化性显著升高,但膨胀力显著降低(P<0.05)。[结论]退火温度预处理和适宜的络合温度有利于HA-SA中RS组分的形成;预处理过程中加热强度的增加使淀粉过度糊化,阻碍了直链淀粉与脂质的络合,络合过程中过高的温度也导致复合物中RS组分的解离,使RS含量降低;退火预处理使HA保留了完整的颗粒结构,是HA-SA抗消化性高的原因之一。

聚乳酸改性糯玉米淀粉酶解产物的结构解析

该文通过考察不同淀粉酶对聚乳酸改性糯玉米淀粉还原糖含量的影响,得到最优组合酶解方法:异淀粉酶酶解10 h+普鲁兰酶酶解10 h+α-淀粉酶酶解10 h+β-淀粉酶酶解12 h。将组合酶解产物以环己烷提取,核磁共振氢谱结果表明,含有乳酸基团的碳水化合物能被有效提取富集,且与未取代的碳水化合物实现分离;质谱分析证明,聚乳酸改性糯玉米淀粉主要由乳酸酯和二聚乳酸酯所构成。该研究探索建立了有效的分离和解析方法,促进了对淀粉酯精细结构的科学认识。

水热处理温度对玉米淀粉-绿原酸复合物结构及消化性能的影响

分别在不同水热处理温度(60℃、70℃、80℃和90℃)下制备玉米淀粉-绿原酸复合物,并通过其绿原酸含量、复合指数(CI)、晶体结构、体外消化性能等探究水热处理温度对玉米淀粉-绿原酸复合物结构及消化性能的影响。结果表明:随着水热处理温度的升高,玉米淀粉-绿原酸复合物中的CI逐渐由4.27%增加至10.65%,绿原酸含量先增加后减少,80℃下制备的玉米淀粉-绿原酸复合物所结合的绿原酸含量最多(6.13 mg/g),而过多的绿原酸虽能促进玉米淀粉双螺旋的形成,但会阻碍玉米淀粉重新形成有序的晶体结构;玉米淀粉-绿原酸复合物结构随水热处理温度升高而发生的变化会导致其糊化稳定性升高和抗消化性能增强,抗消化淀粉(RS)含量由20.49%增加到30.69%。因此,通过控制水热处理温度,可调节玉米淀粉与绿原酸之间的相互作用,进而调控玉米淀粉的消化性能。

The Optimization of Synthesizing Graft Copolymer of Starch with Vinyl Monomers

The graft copolymerization of acrylamide （ AM ） / acrylic acid （ AA ） onto starch （ St- g-pAA and St-g-p（AA-co-AM） ） was carried out using an orthngonal test method. The combined effects of different reaction conditions on the water absorbency of the graft copolymers were optimized through mathematical statistical methods of range and square variance analysis. The maximum water absorbency was obtained when the ratio of dried starch to distilled water was 1 ： 8 （ w/w ）, the ratio of starch to monomer 1 ： 6 （ w/w ）, the initiator concentration 4.40 × 10^-3 mol/L, the crosslinker concentration 10.86 × 10^-2 mol/L, and the basicity to AA 0. 70（ mol/mol ）. Both the graft copolymers have an excellent water absorption capacity in distilled water aact in 0. 9wt% NaCl solution. It was also found that in distilled water the water absorbency of St-g-pAA was higher than that of St-g-p（ AA-co-AM） , while in 0.9wt% NaCl solution, the situation was just the reverse. The correlation between the water absorbeacy anct the nature of the solution anct the properties of the copolymers, which is related to the properties of the monomers, was discussed. The grafting of AA ancl AM onto starch was confirmed by the IR spectra of St-g-pAA and St-g-p（ AA-co-AM）.

刺梨渣中脂肪酸与玉米淀粉包合工艺及在染料吸附中的应用

以刺梨酒厂残渣为原料,对其进行脂肪酸提取纯化后,利用Zabar法制备玉米淀粉-脂肪酸包合物,以吸收率为指标,采用响应面法对包合工艺条件进行优化。实验结果表明,经过纯化,脂肪酸中亚油酸和亚麻酸的含量由74.70%提高到99.06%。包合的最佳工艺条件为:玉米淀粉∶脂肪酸投料比为8.2∶1,包合时间83.6 min,包合温度51.8℃,在此工艺条件下吸附率为94.27%,因素影响次序为包合温度>包合时间>投料比。IR、SEM对包合物表征结果显示包合物已经形成。

Adsorption of Cu^(2+)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 Cu^(2+)initial concentration of the solution on the adsorption performance of the crosslinked graft copolymer were also investigated.The results showed that the Cu^(2+)adsorption capacity of the AA/HA/Starch graft copolymer increased firstly and then decreased with increasing adsorbent dosage and the initial pH value of Cu^(2+)solution.With the increase of Cu^(2+)initial concentration and the extension of adsorption time,the adsorption amount of Cu^(2+)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 Cu^(2+)solution with Cu^(2+)initial concentration of 100 mg/L,the Cu^(2+)adsorption capacity of the crosslinked graft copolymer was 238 mg/g.The adsorption of Cu^(2+)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 Cu^(2+)from industrial wastewater.

壳聚糖/玉米淀粉交联膜的制备及性能研究

以壳聚糖(CS)和玉米淀粉(St)为原料、柠檬酸(CA)为交联剂,采用流延法制备了CS/St/CA交联膜。研究了CS与St的质量比以及CA的含量对CS/St/CA膜热稳定性、水溶性、阻湿性以及力学性能的影响。结果表明,CA的加入对CS/St膜的性能有明显影响,且当CS/St的质量比为2/1,CA在溶液中的质量分数为2%时,所制备的CS/St/CA交联膜的综合性能最优。此时,薄膜的最大热分解温度为366.3℃,质量保留率为28.29%,含水量为8.16%,水溶性为28.48%,溶胀度为18.72%,薄膜表面的水接触角为101.5°,薄膜的水蒸气透过量为8 g/(m^(2)·24 h),降低了12.25倍,水蒸气透过系数为0.488×10^(-13)g•cm/(cm^(2)·s·Pa),拉伸强度从3.7 MPa提高到了12.5 MPa,断裂伸长率从85.3%提高到了113.2%。

新型两性淀粉基絮凝剂的制备

以过硫酸铵为引发剂,在可溶性淀粉上同时接枝丙烯酰胺、甲基丙烯酰氧乙基三甲基氯化铵和丙烯酸,制备了一种新型两性淀粉基絮凝剂。采用红外光谱对接枝共聚物的结构进行表征,证明3种单体成功接枝到淀粉上。为制备高电荷密度、阴阳离子相互匹配的淀粉接枝聚合产品,固定3种单体摩尔比为1∶1∶1,淀粉与单体质量比1∶2.47,通过正交试验对合成条件进行优化,确定接枝共聚反应的最佳反应条件:淀粉与过硫酸铵质量比25∶1,引发时间22 min,反应温度63℃,pH 4~5,聚合体系有效物质量分数17%。最佳反应条件下单体总转化率为99.15%,接枝物的接枝率达到225%,接枝效率达到97.72%。研究提高了在水介质中制备淀粉基改性类高分子絮凝剂的有效物浓度,有利于节约储运成本。

淀粉接枝丙烯酸高吸水性树脂的制备及重金属离子吸附研究

以水解淀粉为骨架,丙烯酸(AA)、过硫酸铵(APS)、N,N'-亚甲基双丙烯酰胺(MBA)为原料,通过接枝聚合法合成淀粉基丙烯酸系高吸水性树脂(SAP),并对其结构进行表征与分析,研究该树脂在不同吸附条件下对重金属离子Ni^(2+)、Co^(2+)和Cr^(6+)的吸附性能。结果表明:所制备的高吸水性树脂是一种多孔网络结构的高分子聚合材料,它对金属离子的吸附属于离子交换机制;SAP对Ni^(2+)、Co^(2+)和Cr^(6+)的吸附量随溶液pH、吸附时间、初始质量浓度增大而提高;对Ni^(2+)、Co^(2+)和Cr^(6+)的吸附行为符合准二级动力学模型和Langmuir等温吸附模型;SAP循环再生4次后仍具备显著的吸附效果。

Directional Breeding of High Itaconic Acid Yielding Strain of <i>Aspergillus terreus</i>with a New Plate Technique

Itaconic acid is commercially produced by the cultivation of Aspergillus terreus using starch hydrolysate as carbon source. The degree of hydrolysis had a great influence on itaconic acid production which was suitable when corn starch was saccharified at 35 DE. The α-amylase was sufficient to drive the starch hydrolysis to the degree. The agar plate assay with LiCl treatment provided a rapid, simple and unequivocal method for screening large numbers of colonies for itaconic acid producing strains. It was learned by experience that the strains on the plates with thick hyphae and light-colored spores often accompanied high itaconic acid production. A strain, designated Ast165, producing itaconic acid with a high yield, was successfully obtained by directional breeding of metabolic end products resistant strains. The itaconic acid concentration produced by Ast165 was 53.8 g/l from 100 g/l of starch hydrolysate in shake flasks. The conversion rate was 61.3%, which was the highest value found in tests.

Preparation and swelling properties of a starch-g-poly（acrylic acid）/organo-mordenite hydrogel composite

A novel hydrogel composite was prepared via inverse suspension polymerization using starch, acrylic acid and organo-mordenite micropowder with the cross- linker, N,N＇-methylenebisacrylamide and the initiator, potassium persulfate. Fourier transform infrared spectro- scopy, X-ray diffraction spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy confirmed that the acrylic acid was grafted onto the backbone of the corn starch, that the organo-mordenite participated in the polymerization, and that the addition of organo-mordenite improved the surface morphology of the hydrogel composite. The swelling capacity of the hydrogel compo- site was evaluated in distilled water, and solutions with different pH values, and various salt solutions. It was found that the incorporation of 10wt-% organo-mordenite enhanced the water absorbency by 144% （from 268 to 655 g-gl） and swelling was extremely sensitive to the pH values, the concentration of the salt solution and cation type. Swelling kinetics and water diffusion mechanism of the hydrogel composite in distilled water were also discussed. Moreover, the hydrogel composite showed excellent reversibility of water absorption even after five repetitive cycles and the hydrogel composite exhibited significant environmental-responsiveness by changing the swelling medium from distilled water to 0.1 mol. L-1 NaC1 solution. In addition, the loading and release of urea by the hydrogel composite were tested and the nutrient-slow- release capability of this material was found to be suitable for many potential applications.

辐射法制备淀粉基超级吸水材料及其性能

本文以淀粉与丙烯酸单体为主要原料,采用钴-60γ射线共辐射法制得淀粉基超级吸水材料(Super absorbent polymer,SAP)。通过傅里叶变换红外光谱对SAP进行化学结构表征。扫描电镜图显示,SAP颗粒表面含有大量中孔结构。热重分析测试结果表明,SAP较原始淀粉样品的热稳定性有明显提升。吸收剂量、丙烯酸与淀粉的投料比显著影响SAP的吸水性能。通过筛选反应条件,SAP的吸水(去离子水)倍率可达到532 g/g(吸收剂量:20 kGy;交联剂:80 mg/L;淀粉与丙烯酸投料比:1/2)。将SAP负载硝酸钾和磷酸钠,结果表明,SAP能够高效释放负载的离子,磷酸根离子释放率为80%,钾离子为82%。

高静水压处理对玉米淀粉/阿魏酸复合体系理化及结构特性的影响

本实验探讨了高静水压(high hydrostatic pressure,HHP)处理对CS玉米淀粉(corn starch,CS)/阿魏酸(ferulic acid,FA)复合体系理化及结构特性的影响。利用差示扫描量热仪、流变仪、傅里叶变换红外光谱仪、X射线衍射仪等技术手段,对HHP处理所构建的CS/FA复合体系的理化性质和结构特性进行研究。结果表明,HHP处理增强了CS/FA复合体系的峰值黏度、弹性模量G′和黏性模量G″,降低了复合体系的溶解度和膨胀度(75~95℃)、糊化焓及回生值;此外,HHP处理提高了CS/FA复合体系的粒径,傅里叶红外光谱和X射线衍射光谱分析结果表明,HHP处理后复合体系短程有序和双螺旋结构程度降低,淀粉颗粒仍为A型而相对结晶度下降。综上所述,HHP处理促进了复合体系中CS与FA的相互作用,改善了CS的理化特性,使其结构有序程度降低。

两种共聚单体对淀粉/聚丙烯酸钠超级吸水材料耐盐性能的影响

利用γ射线共辐照法,制备了由两种共聚单体接枝交联而成的淀粉基超级吸水材料(Super absorbent polymer,SAP)。傅里叶变换红外光谱证明了丙烯酰胺(AM)和2-丙烯酰氨基-2-甲基-1-丙烷磺酸(AMPS)分别被引入到淀粉/聚丙烯酸钠(Starch-g-PAA)SAP中。采用热重分析法研究了SAP的热分解行为。通过引入AM和AMPS单体,SAP的耐盐性得到显著提升,引入AMPS的SAP在生理盐水中的吸液倍率从46 g/g(未添加AMPS)提高至81 g/g(AA∶AMPS=3∶1)。

辛烯基琥珀酸玉米淀粉酯的盐酸水解及其Pickering乳液的稳定性

为探究辛烯基琥珀酸淀粉酯疏水基团和淀粉粒径对Pickering乳液稳定性的影响,使用1 mol/L盐酸对辛烯基琥珀酸玉米淀粉酯(octenyl succinate anhydride corn starch, OSACS)进行水解处理,得到不同水解程度的样品并将其制成Pickering乳液,利用扫描电子显微镜、激光粒度仪、傅里叶红外光谱分析仪、差示扫描量热仪、显微镜、流变仪等分析盐酸水解前后淀粉颗粒的理化性质及乳液的性质。结果表明:随着酸水解时间的增加,OSACS的取代度由0.020 3减小至检测不出,糊化温度逐渐降低,平均粒径由18.09μm减小至6.22μm,结晶度从19.98%增加至25.91%;取代度为0.020 3的OSACS能够形成液滴尺寸较小的稳定乳液,乳液的流变学特性表明所有乳液均具有剪切稀化的性质,未经盐酸水解的OSACS颗粒形成乳液的储能模量高于盐酸水解处理后的淀粉颗粒所形成乳液的。微米级粒径的变化范围内,粒度的减小并未对Pickering乳液的稳定性产生显著影响,辛烯基琥珀酸基团在Pickering乳液的稳定性中起到了主导作用。

多壁碳纳米管分散剂的制备及分散性能研究

由于碳纳米管(CNTs)自身较大的比表面积及碳管间强的作用力,使其在溶剂中不易分散,因此应用前需要进行分散处理,使其能够满足更多应用的需求。利用在淀粉上接枝丙烯酸(AA)或苯乙烯(St),分别制备了淀粉接枝丙烯酸聚合物(SAa)、苯乙烯聚合物(SSty)、丙烯酸-苯乙烯聚合物(SSA)新型分散剂,并研究在水中对多壁碳纳米管(MWCNTs)的分散性。结果表明:改性淀粉的分子量(Mw)由4.25×105减小到3.92×10^(5)、分子量分布系数(M_(w)/M_(n))由3.01减小到了2.88,分子量分布较窄,聚合物的结构更加稳定;改性淀粉颗粒溶胀崩解,原有形貌发生改变,晶型受到破坏,尺寸变小更有利于分散;此外,对于0.10 g∙L^(−1)的MWCNTs,使用SSA的MWCNTs分散效果最好,SSA分散MWCNTs在20 d时的沉降率为30.6%。通过机理研究发现,SSA利用结构中接枝聚合的苯环与MWCNTs的p―p非共价键吸附在MWCNTs表面,通过静电斥力和空间位阻效应的协同作用对MWCNTs进行分散,因而SSA比SAa和SSty更能有效地降低水中MWCNTs的聚集趋势。