Carboxymethylation of γ‐irradiated starch

Low viscosity carboxymethyl corn starch was prepared by the reaction of γ‐irradiated starch with monochloroacetic acid in the presence of alkali. It was found that irradiation dose influences the product viscosity remarkably. The viscosity decreases as the irradiation dose level increases; however, the viscosity increases with the increasing dose rate and the degree of substitution (DS). γ‐Irradiation can activate the starch to react with monochloroacetic acid, and the more of the irradiation dose, the higher of the DS and the reaction efficiency. The product has the character of low viscosity at high concentration, and the more of the irradiation dose, the more similar of the rheological behavior to a Newtonian liquid. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2210–2215, 2006     

高交联非晶颗粒态玉米淀粉制备方法研究

报道了高交联、水分散体系高温溶胀、高交联碱糊化协同作用非晶颗粒态玉米淀粉的制备方法 ,采用偏光显微镜对其由多晶态向非晶态的变化进行了确认 ,提出在一定条件下 ,高交联玉米淀粉可以由原淀粉多晶颗粒态制备成只含无定形结构的非晶颗粒态淀粉     

Chemical modification of starch. II. Cyanoethylation

Rice starch was cyanoethylated by reacting it with acrylonitrile in presence of sodium hydroxide at different concentrations of acrylonitrile and various reaction temperatures. The effect of cyanoethylation on the rheological and solubility properties of starch was examined. It was found that the extent of the cyanoethylation reaction [expressed as %N and degree of substitution (DS)] increased by increasing acrylonitrile concentration provided that the latter was not less than 8 ml acrylonitrile per 10 g starch. A temperature of 50°C constituted the optimal temperature for the cyanoethylation of starch under the conditions studied. Examination of the rheological properties of the modified starch revealed that regardless of the DS, cyanoethylated starches are characterized by pseudoplastic behavior of particular interest were the results of the viscosity. Cyanoethylated starch having smaller amounts of cyanoethyl groups had higher viscosity than those of relatively larger amounts. On the other hand, the cyanoethylated starches were soluble in water regardless of the extent of cyanoethylation.     

Microwave-assisted reaction of gelatin with tannic acid: non-thermal effect on the crosslinking process

The reaction of gelatin with tannic acid using microwave heating with simultaneous cooling (MHSC) in comparison with water bath heating was investigated to get some hints on the non-thermal effect of microwave. MHSC showed a better ability to accelerate the reaction rate. It also increased the turbidity, crosslinking degree, and viscosity of the crosslinked gelatin by 91 FTU, 6.8%, and 0.08 respectively, indicating that microwave could improve the properties of the product. Moreover, sodium dodecyl sulfate polyacrylamide gel electrophoresis patterns reflected that the crosslinked gelatin (MHSC) had a higher molecular weight as the gray levels decreased by 9.2% (235–245?kDa), 2.3% (135–145?kDa), and 9.3% (122–132?kDa). More homogeneous aggregations were identified at the crosslinked gelatin by atomic force microscopy. These results proved that microwave has a non-thermal effect in the gelatin crosslinking process, accelerating the crosslinking reaction, and improving the performance of the gelatin product, which may have a good use in industry.     

Hydrogels of starch/carboxymethyl cellulose crosslinked with sodium trimetaphosphate via reactive extrusion

Hydrogels are materials with advantages in specific applications, such as, retention of food active compounds. This work aims to develop starch (S)/carboxymethyl cellulose (CMC) hydrogels with porous structure, using reactive extrusion to promote crosslinking with sodium trimetaphosphate (STMP). The expansion, porosity, degree of substitution, gel fraction, swelling properties, and FTIR are studied, comparing S, S/CMC, S/STMP, and S/CMC/STMP formulations. Samples containing STMP present the same degree of substitution (0.050 ± 0.001). Higher porosity and percentage of open pores are observed in the mixed hydrogel (S/CMC/STMP). Crosslinking increase the swelling capacity at pH 7, and this property, just like the gel fraction, are sensitive to pH variations. The hydrogel S/CMC present the highest swelling rate compared with the other samples, suggesting strong interaction between components. The reactive extrusion process is efficient to produce starch and starch/CMC hydrogels crosslinked with STMP and the overall results demonstrate the advantages of the mixed hydrogel.     

Physicochemical studies of crosslinked thiolated polyvinyl alcohol hydrogels

This study is related to the post-crosslinking of thiolated polyvinyl alcohol (TPVA) hydrogels using three crosslinkers, sodium trimetaphosphate (STMP), boric acid (BA) and glyoxal (GLY) under alkaline conditions. The crosslinking reaction was carried out under different conditions: crosslinker nature, crosslinker content and crosslinking time. The influence of different crosslinkers on the physicochemical and structural characteristics of TPVA was evaluated. The three reagents used for crosslinking presented different action mode on hydrogels. The optimized crosslinking conditions were the crosslinker content is 0.1 % (w/v) at crosslinking time of 30 min. The results showed that the STMP-crosslinked TPVA had the maximum thiol content and swelling ability. All crosslinked TPVA samples were stable in different pH media. The involvement of thiol and other relevant groups after crosslinking in the different crosslinked TPVA samples was confirmed by attenuated total reflectance-infrared spectra. The microanalysis of elements present in the crosslinked samples were analyzed by energy-dispersive X-ray microanalysis.     

Characterization and physiochemical studies of crosslinked thiolated polyvinyl alcohol hydrogels

Modification and crosslinking of polyvinyl alcohol (PVA) by thiolation using thioglycolic acid (TGlA) and various crosslinkers were carried out. The crosslinked thiolated PVA (TPVA) hydrogels were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infra red spectroscopy coupled with thermal analysis (TG-FTIR) techniques. The crosslinking of the resultant material was carried out using three crosslinker sodium trimetaphosphate (STMP), glyoxal and boric acid. The influence of esterification and crosslinking on the physical and chemical properties of the material was studied. XRD showed that after crosslinking the crystallinity of TPVA hydrogels decreased. These results were further substantiated by DSC observations. The thermal stability of the TPVA hydrogels is enhanced. A significant variation in the initial decomposition temperature was observed with respect to different STMP crosslinked samples having varying TGlA concentration and different crosslinkers. The coupled TG-FTIR studies of crosslinked samples at different temperatures show that the evolution of sulfur-containing gases (carbon disulfide and carbon monosulfide) is being prominent for this material.     

微波辅助复合氧化法合成氧化玉米淀粉

以玉米淀粉为原料、以过氧化氢和过硫酸钾为复合氧化剂、以Fe2＋为催化剂,在酸性条件下采用微波辅助复合氧化法合成氧化玉米淀粉。以反应温度、微波催化合成/萃取仪功率、催化剂质量分数（占干淀粉总量,下同）、复合氧化剂质量分数（占干淀粉总量,下同）、淀粉乳浓度、体系pH值、反应时间等因素为变量,以氧化度为衡量指标,采用单因素实验和正交实验确定微波辅助复合氧化法合成氧化玉米淀粉的最佳工艺条件为：反应温度55℃、微波催化合成/萃取仪功率400 W、催化剂质量分数0.3%、复合氧化剂质量分数8%、淀粉乳浓度45%、体系pH值4.00、反应时间21min,在此条件下,可以制得氧化度为0.140%的氧化玉米淀粉。     

Hydrogel of biodegradable cellulose derivatives. I. Radiation‐induced crosslinking of CMC

Radiation crosslinking of carboxymethylcellulose (CMC) with a degree of substitution (DS) from 0.7 to 2.2 was the subject of the current investigation. CMC was irradiated in solid‐state and aqueous solutions at various irradiation doses. The DS and the concentration of the aqueous solution had a remarkable affect on the crosslinking of CMC. Irradiation of CMC, even with a high DS, 2.2 in solid state, and a low DS, 0.7 in 10% aqueous solution, resulted in degradation. However, it was found that irradiation of CMC with a relatively high DS, 1.32, led to crosslinking in a 5% aqueous solution, and 20% CMC gave the highest gel fraction. CMC with a DS of 2.2 induced higher crosslinking than that with a DS of 1.32 at lower doses with the same concentration. Hence, it was apparent that a high DS and a high concentration in an aqueous solution were favorable for high crosslinking of CMC. It is assumed that high radiation crosslinking of CMC was induced by the increased mobility of its molecules in water and by the formation of CMC radicals from the abstraction of H atoms from macromolecules in the intermediate products of water radiolysis. A preliminary biodegradation study confirmed that crosslinked CMC hydrogel can be digested by a cellulase enzyme. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 278–283, 2000     

微波辐射下双酶催化淀粉水解的动力学研究

以玉米淀粉为反应底物,研究了α-淀粉酶和糖化酶分别在微波辐射和水浴加热条件下水解玉米淀粉的动力学特性。考察了pH、温度、底物质量浓度、酶用量对玉米淀粉水解反应速率的影响。结果表明,微波辐射条件下的平均反应速率比水浴加热提高了20%以上。以米氏方程为基础,研究了两种加热方式下的米氏常数Km、最大反应速率νm和抑制常数Ki。结果表明,微波辐射下α-淀粉酶的Km=3 922.76 g/L,νm=1.72×10-3mol/(mL.min),糖化酶的Km=173.31 g/L,νm=3.289×10-5mol/(mL.min);水浴加热条件下α-淀粉酶的Km=312.03g/L,νm=1.21×10-4mol/(mL.min),糖化酶的Km=16.14 g/L,νm=3.89×10-6mol/(mL.min);微波辐射下糖化酶的抑制常数(Ki)低于水浴加热的抑制常数。     

碱溶解玉米淀粉制备高吸水性树脂

以玉米淀粉、丙烯酸为原料,过硫酸铵(APS)为引发剂,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,将中和丙烯酸的NaOH提前加入体系溶解淀粉,一步法制备出淀粉基高吸水性树脂(SSAP1)。通过单因素实验探究了丙烯酸与玉米淀粉质量比、丙烯酸中和度、引发剂APS用量、交联剂MBA用量对产物吸水倍率的影响,获得最优制备参数。通过FTIR、XRD、SEM分析了SSAP1微观结构,对比了SSAP1和高温糊化淀粉制备出淀粉基高吸水性树脂(SSAP)的接枝率和应用性能。结果表明,碱溶解玉米淀粉成功接枝聚丙烯酸分子链并发生交联反应形成高吸水性树脂,该方法能更有效地破坏淀粉分子内氢键并提高反应效率;SSAP1吸水速率与重复吸水性能优于SSAP;SSAP1在蒸馏水和盐水(0.1 mol/L NaCl溶液)中的吸收倍率分别为464和34 g/g,相比SSAP的吸水倍率(428 g/g)和吸盐水倍率(26 g/g)有明显提升。     

Pullulan–STMP hydrogels: a way to correlate crosslinking mechanism,structure and physicochemical properties

Rheological and swelling properties of hydrogels based on pullulan crosslinked with sodium trimetaphosphate (STMP) are explained according to various polymer and crosslinking agent concentrations using ³¹P-nuclear magnetic resonance study. This method has allowed determining the amount of all the species present in the medium when varying both pullulan and STMP concentrations. We have clearly demonstrated with a good agreement by both ³¹P-NMR and rheology that a critical STMP concentration occurs which is function of pullulan concentration. This typical crosslinking agent concentration delimitates the maximum of gel structure together with the minimum of swelling.     

Properties of starch‐based blend films using citric acid as additive. II

Starch/polyvinyl alcohol (PVA) blend films were prepared by using corn starch, polyvinyl alcohol (PVA), glycerol (GL), and citric acid (CA) as additives and glutaraldehyde (GLU) as crosslinking agent for the mixing process. The additives, drying temperature, and the influence of crosslinker of films on the properties of the films were investigated. The mechanical properties, tensile strength (TS), elongation at break (% E), degree of swelling (DS), and solubility (S) of starch/PVA blend film were examined adding GL and CA as additives. At all measurement results, except for DS, the film adding CA was better than GL because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA, and additives. CA improves the properties of starch/PVA blend film compared with GL. TS, % E, DS, and S of film adding GLU as crosslinking agent were examined. With increasing GLU contents, TS increases but % E, DS, and S value of GL‐added and CA‐added films decrease. When the film was dried at low temperature, the physical properties of the films were clearly improved because the hydrogen bonding was activated at low temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2554–2560, 2006     

The graft copolymerization of corn starch by microwave irradiation with rheological phase reaction

The corn starch was grafted by microwave irradiation with rheological phase reaction, to meet the sizing requirements of polyester/cotton blended yarn and avoid the disadvantages of corn starch size including brittle, hard, and size shedding. On the basis of the damping characteristics of corn starch film and the polarity of grafting monomer, the grafting effect of grafted corn starch was researched by using infrared spectroscopy, SEM, rotary viscometer, and thermomechanical analyzer. The results showed that both hydrophilic groups and hydrophobic groups were introduced in the molecular chains of grafted corn starch. The storage modulus of grafted corn starch film reached 285–315 MPa, being four times higher than that of nongrafted corn starch film. Compared with corn starch sizing, the viscosity of grafted corn starch sizing decreased 62.5%. Furthermore, through analyzing grafting law and establishing regression equation, it was indicated that the irradiation time and initiator content influenced the grafting ratio of grafted starch significantly. The grafting ratio could reach 19.57%, when the irradiation time and initiator content were selected with 3.5 min and 4.55%, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

歧化松香缩水甘油木薯淀粉酯的微波合成及表征

在微波辐照下,以DMAc/L iC l为溶剂体系,歧化松香缩水甘油酯和木薯淀粉亲核开环反应得到歧化松香缩水甘油木薯淀粉酯(DGCSE),探讨了各反应因素对产物取代度的影响。目标产物的最佳合成条件:反应温度110℃,反应时间1.5 h,NaOH用量1.2 g,摩尔比3∶1(歧化松香缩水甘油酯∶葡萄糖单元中羟基数)及微波功率700 W。元素分析,IR,UV,SEM,TG-DTA和XRD分析表明,与原料木薯淀粉相比,DGCSE表面形态由有序变得杂乱,结晶度大幅度下降,热稳定性能得到改善。     

阳离子改性淀粉絮凝剂的制备及应用

以糯玉米淀粉为原料,3-氯-2-羟丙基三甲基氯化铵为阳离子醚化剂,采用预干燥干法制备高取代度季铵型阳离子淀粉絮凝剂.考察了醚化剂用量、氢氧化钠与醚化剂摩尔比、反应温度及反应时间对取代度的影响,优化出制备高取代度阳离子淀粉的最佳工艺条件为:醚化剂的加入量为绝干淀粉量的52.5%,氢氧化钠与醚化剂摩尔比为1.2,反应温度80℃,反应时间5 h.将阳离子淀粉对玫瑰花色素酒精废液进行絮凝脱色性能测定,结果表明当阳离子淀粉量浓度为1250 mg·L-1、取代度为0.3342时,脱色率达78.42%.     

Hydrogels Based on Pullulan Crosslinked with sodium trimetaphosphate (STMP): Rheological study

Summary Hydrogels from pullulan crosslinked with sodium trimetaphosphate (STMP) under alkaline condition have been investigated by rheological measurements. The influence of reagents concentration (pullulan, STMP, NaOH) on kinetics of reaction and rheological properties is reported. Increasing concentrations of any reagents lead to an increase of the crosslinking kinetics. Increasing the polymer concentration leads to a stronger gel whereas an increase of crosslinking reagent (STMP) evidences a critical concentration above which the rheological properties of the gel do not change anymore. This may be explained by the specificity of the system for which the polymer concentration is high and negative charges appear.     

Effect of unmodified and modified sago starch on properties of (sago starch)/silica/PVA plastic films

Sago starch was modified by crosslinking with sodium trimetaphosphate (STMP). Different formulations of films were prepared by a blending process and a casting method. A suitable plasticizer was added to the blend. Mechanical properties of plastic films with unmodified and modified sago starch were compared. From the results obtained, films with modified sago starch had better compatibility and interaction with polyvinyl alcohol than unmodified sago starch films. Thus, the tensile strength of modified films was higher, but lower in elongation at break than unmodified sago starch plastic films. Films with modified sago starch also showed lower water absorption, water vapor transmission, and degradation than unmodified sago starch plastic films. Chosen were 1 wt% and 2 wt% of silica as the optimum formulation that produced the best tensile properties for modified and unmodified sago starch plastic films. J. VINYL ADDIT. TECHNOL., 20:185–192, 2014. © 2014 Society of Plastics Engineers     

多孔性交联淀粉絮凝剂的制备研究

以玉米淀粉为原料,先用a-耐高温淀粉酶处理,制备多孔玉米淀粉,然后以环氧氯丙烷(ECH)为交联剂,合成具有多孔结构的颗粒态交联淀粉絮凝剂,并对交联工艺进行了初步优化。制备多孔交联淀粉的最佳条件为:25 g多孔淀粉,碱性硫酸钠溶液用量50 mL,环氧氯丙烷用量0.75mL,反应温度25℃,反应时间18 h。     

Influence of crosslinking methods toward poly(vinyl alcohol) properties: Microwave irradiation and conventional heating

In this study, crosslinking of poly(vinyl alcohol) (PVA) with tartaric acid, as crosslinker, is performed using microwave irradiation. A comparison between the properties of PVA crosslinked using microwave irradiation and conventional heating methods is also discussed. While the water absorption, tensile and thermal properties of PVA crosslinked by either of the methods are comparable, microwave irradiation took only one‐eighth (14 min) of the time compared to conventional heating. In comparison with PVA (42 MPa), the strength of PVA crosslinked with 35% TA increased to 145 and 153 MPa for conventional heating and microwave irradiation, respectively. Water absorption of crosslinked PVA film is successively reduced to less than 30% in comparison with PVA (～200%). Moreover, the crosslinked films are stable at higher temperatures in comparison with PVA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46125.