水分对微波变性木薯淀粉晶体颗粒态的影响

利用偏光显微镜研究了不同水分质量分数对微波变性木薯淀粉的影响,发现微波处理造成颗粒偏光十字的消失始于脐点,经过微波变性绝大多数颗粒偏光十字的亮度有所下降,偏光消失的程度与微波变性时原淀粉的水分质量分数成正比。当水分质量分数达到35.1%时,绝大多数颗粒的偏光消失,微波变性时原淀粉的水分临界点为30%。     

马来酸酐淀粉酯-丙烯酸共聚物的合成及吸水性能的研究

通过马来酸酐淀粉酯与丙烯酸共聚来合成吸水材料,研究了温度、时间、交联剂用量、引发剂用量、马来酸酐淀粉酯用量和蒙脱土用量等对材料吸水倍率的影响。结果表明当反应温度为60℃、反应时间为4h、N,N-二甲基丙烯酰胺为0．02％、过硫酸钾为0．47％、马来酸酐淀粉酯用量为13．6％和蒙脱土用量为13．5％时,得到材料的吸水倍率为：746g／g。     

改性淀粉油田废水处理剂应用可行性分析

针对我国油田废水处理过程中普遍存在着的费用偏高,处理效果不够理想以及处理后的二次污染问题,采用改性淀粉分别对四种典型油田废水的处理效果,药剂的毒性及其经济可行性进行了系统的考察和分析。研究结果表明,此类化合物的综合评估效果优于聚丙烯酰胺类水处理剂,将其用于石油工业废水的净化处理是可行的。     

Fabrication and properties of thermoplastic starch/montmorillonite composite using dialdehyde starch as a crosslinker

The poor mechanical properties and high water solubility of biodegradable thermoplastic starch (TPS) represent the main disadvantages of TPS in many applications. In this work, TPS film was prepared from a water solution of corn starch modified by 5 wt% dialdehyde starch (DAS) as crosslinking agent and 3 wt% montmorillonite (MMT) as reinforcing additive. Interactions occurring in the TPS films were investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, XRD, DSC, dynamic mechanical thermal analysis (DMTA) and TGA. The results obtained fom FTIR spectroscopy and DSC suggest the formation of hydrogen bond interactions between the hydroxyl group of starch, DAS, the MMT layers and glycerol. DMTA indicated that the relaxation of films with DAS and MMT appears in a higher and broader temperature range due to the starch backbone stiffness; the extreme increase in the storage modulus confirmed the suggested interactions. The determination of the weight loss of the films in water indicated a significant increase of the water resistance of TPS due to incorporation of DAS and MMT. Changes in mechanical properties of the films containing DAS and clay were determined, showing a substantial increase in tensile strength from 2.7 to 6.7 MPa, while Young's modulus increased by 15 times for TPS modified with 5% DAS and 3% MMT. Therefore, the outcomes of this study confirmed that DAS is a suitable biomacromolecule crosslinker for starch and can significantly enhance TPS and TPS/MMT properties. © 2019 Society of Chemical Industry     

The synthesis and incorporation of a star-shaped bio-based modifier in the acrylic acid based superabsorbent: a strategy to enhance the absorbency under load

ABSTRACT

The mechanical strength of superabsorbents is an important practical factor that can be characterized by measuring the absorbency of the superabsorbent under load. In the last decades, many efforts have been devoted to enhancing the mechanical strength of superabsorbents. Herein, as an attempt to increase the superabsorbent mechanical strength, two types of star-shaped bio-based modifiers were designed and synthesized via condensation reaction between acids and alcohols. The chemical structures of the bio-based modifiers were characterized via FT-IR and ¹H NMR analysis. Glycerin, lactic acid, succinic acid, and itaconic acid used for the synthesis of the star-shaped modifier, which further used in different ratios in the bulk of the superabsorbent. Moreover, another modifier was synthesized from glycerin, lactic acid, and methacrylic anhydride, and successfully used as a surface modifier for superabsorbents in different ratios. The absorption analysis showed that the employment of the optimum amount of the bulk modifier (4.75 wt.%) increases the AUL almost 4 units, without significant impacts on the water and NaCl solution absorbencies. Also, the incorporation of the optimum amount of the surface modifier increases the AUL about 3 units. As a result, the AUL value of the acrylic acid- sodium acrylate superabsorbent enhanced ~7 units by the incorporation of these bio-based modifiers-from 17.3 for the pristine superabsorbent to 24.2.     

Epoxidized natural rubber as a reinforcement modifier for silica‐filled nitrile rubber

Hydrated silicas impart better physical properties to polar rubbers, compared to those of hydrocarbon rubbers. However, to achieve optimum properties silane coupling agents are crucial in such formulations. Epoxidized natural rubber (ENR) in small proportions is used as a reinforcement modifier for silica‐filled nitrile rubber (NBR). Two systems of cure were used: N‐cyclohexyl‐ 2‐benzthiazyl sulfenamide (CBS) alone and in combination with diphenyl guanidine (DPG). In the CBS accelerated system, incorporation of an optimum concentration of about 15% of ENR on total rubber was found to improve technological properties. Addition of a secondary accelerator further improves these properties. Comparable results are obtained with those containing coupling agent and NBR–ISAF. High bound rubber and volume fraction values indicate a high polymer–filler interaction and gel content resulting from the NBR–ENR interaction. Results of this study reveal that ENR could be used as a reinforcement modifier for the NBR–silica system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 292–306, 2002     

Use of maleic anhydride–grafted polyethylene as compatibilizer for HDPE–tapioca starch blends: Effects on mechanical properties

Tapioca starch in both glycerol‐plasticized and in unplasticized states was blended with high‐density polyethylene (HDPE) using HDPE‐g‐maleic anhydride as the compatibilizer. The impact and tensile properties of the blends were measured according to ASTM methods. The results reveal that blends containing plasticized starch have better mechanical properties than those containing unplasticized starch. High values of elongation at break at par with those of virgin HDPE could be obtained for blends, even with high loading of plasticized starch. Morphological studies by SEM microscopy of impact‐fractured specimens of such blends revealed a ductile fracture, unlike blends with unplasticized starch at such high loadings, which showed brittle fracture, even with the addition of compatibilizer. In general, blends of HDPE and plasticized starch with added compatibilizer show better mechanical properties than similar blends containing unplasticized starch. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 863–872, 2001     

Using SBS/terpene-styrene resin blends as a novel high-viscosity asphalt modifier

To improve the inferior stability in high-viscosity asphalt prepared using styrene-butadiene-styrene block copolymer (SBS) and to simplify the preparation process, a novel high-viscosity modifier (STP) was prepared with SBS, terpene-styrene resin (TSR) and plasticizer. Its inherent properties, optimal dosage, and modification effect were investigated. The results show that STP has lower component melting temperature and stronger polarity, combined with good thermal stability, ensuring that STP possesses a better modification effect on asphalt. 14.5–17.6 wt% was determined as the appropriate content of STP. The incorporation of STP improved the rutting resistance and elasticity percentage of the asphalt. The zero shear viscosity (ZSV) of asphalt fitted by the Carreau model showed that STP increased the cohesion of the asphalt system and improved the high-temperature deformation resistance. The small non-recoverable creep compliance value proves that the STP high-viscosity asphalt (STP-HVA) exhibits excellent resistance to permanent deformation at high-temperatures while displaying low-stress sensitivity and achieving an extremely heavy traffic rating. STP confers greater flexibility to asphalt to eliminate low-temperature cracking phenomenon. Smaller CMAI and PAAI values demonstrate that STP-HVA exhibits outstanding aging resistance. TSR effectively improves the compatibility of SBS and base asphalt, and STP particles are finely dispersed and uniform. The preparation process is mainly physical modification, accompanied by chemical reactions.     

淀粉疏水改性技术的研究进展

综述了淀粉疏水改性技术的应用情况及淀粉基降解塑料的国内外研究现状,着重介绍了应用较为广泛的几种淀粉疏水改性技术的优缺点及其发展动向。     

Urea and formamide as a mixed plasticizer for thermoplastic starch

Mixtures of urea and formamide were tested as plasticizers for thermoplastic starch (TPS). The hydrogen bonding interactions between urea/formamide and starch were investigated by using Fourier‐transform infrared spectroscopy (FT‐IR). The thermal stability, mechanical properties and starch retrogradation behavior were also studied by thermogravimetric analysis (TGA), tensile testing and X‐ray diffraction (XRD), respectively. TPS plasticized by urea (20 wt%) and formamide (10 wt%) showed better thermal stability and water resistance than conventional TPS plasticized by glycerol. Moreover, the tensile stress, strain and energy at break, respectively, reached 4.83 MPa, 104.6 % and 2.17 N m after storing in an atmosphere of relative humidity (RH) of 33 % for one week. At the same time, this mixed plasticizer could effectively restrain the retrogradation of starch. Copyright © 2004 Society of Chemical Industry     

Synthesis of SBS thermoplastic block copolymers in cyclohexane in the presence of diethylether used as a structure modifier

Diethylether (DEE) was used as a structure modifier during the synthesis of linear styrene-butadiene block copolymers of poly A-block-polyB-block-polyA type (SBS). The microstructures of synthesized polymers were analyzed, and the effect of DEE on polymerization kinetics was studied. Addition of DEE at 2 wt% concentration results in the highest styrene polymerization rate, while addition at 6 wt% concentration gives the highest butadiene polymerization rate. The vinyl content of the polybutadiene portion increases from 14 to 47% with an increase in the DEE concentration from 500 ppm to 10 wt% while thetrans- l,4 andcis-1,4 isomers decrease. For SBS polymer synthesized via a sequential method, the addition of DEE as a structure modifier minimizes the crossover deficiency which would otherwise result in a skewed molecular weight distribution with a higher polydispersity. For SBS polymers made via a coupling method, the coupling efficiency appears to be constant in a range of DEE concentration from 500 ppm to 1 wt% before declining with a further increase in DEE.     

真空一锅法合成丙烯酸类超吸水树脂

以丙烯酸与木薯淀粉为主要原料,采用一锅法,在真空条件下合成了木薯淀粉矿丙烯酸超吸水树脂（CS＆心）和聚丙烯酸超吸水树脂（PAA）。接枝反应树脂结构经红外光谱（Fr取）、X－射线衍射（XRD）,热重一差热扫描（TGⅨ℃）和扫描电镜（SEM）表征,考察了真空度对CB-SAP吸水能力与接枝效率的影响,结果表明,真空度加大,树脂吸水能力上升,接枝效率升高;在相同工艺条件下,P从的吸水能力远低于CSsAP,该工艺配方更适合制备CB-SAP。     

淀粉发酵体系中威兰胶产品的含量测定与分析

在鞘氨醇单胞菌发酵生产威兰胶的实验中,为去除残余淀粉并准确测定发酵液中威兰胶的产量,比较了吸附法、酸解法、酶解法对威兰胶溶液和淀粉溶液的影响,并采用单因素实验和正交实验优化实验条件。结果表明,酸解法最优,最优条件为:p H=1.0,温度为95℃,时间为180 min,在此条件下,淀粉的去除率达到99.19%,威兰胶的保留率为87.51%。经碘量法验证:威兰胶-淀粉混合溶液在最优条件下酸解,淀粉的去除率和威兰胶的保留率与正交实验所得结果相符;该方法能准确测定含淀粉的发酵液中威兰胶的含量,误差在5%以内。     

反相乳液五元体系淀粉接枝共聚反应动力学

研究了在淀粉/单体/乳化剂/油/水五元反相乳液体系中引发淀粉和丙烯酰胺接枝共聚反应的动力学,考察了引发剂和乳化剂浓度、单体和淀粉浓度、反应温度等因素对表观聚合速率的影响.结果表明：在本实验考察范围内单体浓度和淀粉浓度对聚合速率影响明显,聚合过程中快速链终止和慢速链终止反应同时存在,动力学关系式为：R_p∝［I］^0.93［M］^1.28［St］^1.47［E］^0.61,聚合速率随体系温度的升高而加快,在35～55℃范围内,聚合反应的表观活化能为82.01 kJ•mol^-1.     

Melt rheology and die swell of PA6/LDPE blends by using lithium ionomer as a compatibilizer

Rheological behavior and die swell in blends of polyamide 6/low-density polyethylene with and without compatibilizers were investigated. The compatibilizers used were copolymers of ethylene and methacrylic acid with and without partial lithium neutralization. The results showed that the apparent viscosity, non-Newtonian index, flow activation energy and die swell of the blend are affected by the compatibilizer identity and content. In general, the effects were more significant at low shear rates and lithium-neutralized materials tended to show greater effects than the hydrogen form of the copolymer.     

Synthesis and characterization of a new acrylic adhesive mixture for use in ocular strabismus surgery

A new series of acrylic adhesive mixtures was specifically designed for use in strabismus surgery, more precisely to join the rectus muscles to the sclera. These two-part adhesives consisted of a mixture of ethyl cyanoacrylate (CN) and ethyl carboxyacrylate (ECA). ECA acted as a plasticizer imparting flexibility to the CN, and also as a nonreactive diluent, serving to reduce the exotherm in the reaction between CN and eye tissues. In this article, the synthesis of the ethyl carboxyacrylate is described, and the properties of different ethyl cyanoacrylate + ethyl carboxyacrylate mixtures were studied. The curing reaction of the adhesive mixtures was monitored using Fourier transform infrared (FTIR) spectroscopy and scanning differential calorimetry (DSC). The rheological properties of the cured CN-ECA adhesive films were studied using plate-plate rheometer experiments. To quantify the adhesion, single lap-shear tests produced between a rubber and the adhesive mixtures were performed and, to evaluate the adhesion to eye tissues, tensile strength measurements of superior rectus muscle/adhesive mixture/sclera joints were carried out. The 70CN-30ECA (v/v) adhesive mixture provided the most adequate balance between adhesion and mechanical properties in the joining of the superior rectus muscle to the sclera. The glass transition temperature of the CN-ECA adhesive mixtures linearly decreased with increase in the ECA content, and a lower degree of conversion during polymerization was obtained by increasing the ECA content. As a consequence, the CN-ECA mixtures were less stiff than CN, giving better performance in the joining of the rectus muscles to the sclera. Finally, the adhesion of CN was sufficiently decreased in CN-ECA mixtures, and the locus of failure was directed to the adhesive film in the joint between the rectus muscles and the sclera.     

Synthesis of random or tapered solution styrene–butadiene copolymers in the presence of sodium dodecylbenzene sulfonate as a polar modifier

Random or tapered solution styrene–butadiene copolymer (SSBR) is very difficult to prepare in an isothermal batch process without the use of polar modifiers because of the diverse reactivity ratios of the styrene and the butadiene in hydrocarbon solvents. In the presence of polar modifiers, the random SSBR can be synthesized by anionic living polymerization with the variety of microstructures, which results in the change of glass transition temperature (T_g). This article will discuss the use of sodium dodecylbenzene sulfonate as a polar modifier in isothermal batch process that controls the microstructure of the SSBR resulting in a random as well as tapered SSBR with low T_g (?67°C to ?80°C). The T_g of SSBR was controlled by the styrene content rather than the microstructure of polybutadiene. Physical properties of SSBR compounding were discussed for tire tread applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Graft copolymerization of acrylic acid onto cocoyam starch by ceric ion in the presence of N,N′‐dimethylacetamide

Grafting of acrylic acid onto cocoyam starch, Xanthosoma sagittitolium was initiated by ceric ion—N,N′‐dimethylacetamide redox pair in aqueous media. The reaction was characterized by high graft yields of up to 676%, and infrared spectroscopy affirmed the presence of grafted polymer. Graft yield was enhanced by N,N′‐dimethylacetamide (DMAc) in the concentration range, 9.0–36.0 × 10^?4M but lower concentrations were more favorable with the ratio of percentage graft, P_g/P_g0, in the presence and absence of DMAc respectively, of up to 1.34 at 9.0 × 10^?4M of the latter. Ceric ion was nonterminating of the graft reaction and a 10‐fold increase in its concentration of 4.16 × 10^?3M resulted in high efficiency of graft of 50.2% in monomer conversion to grafted polymer. Enhanced homopolymer formation and low efficiency of graft were observed at monomer concentration greater than 0.69M. Long reaction time, greater than 30 min, was unfavorable to the graft reaction and the latter showed negative dependence on temperature in the range, 30–50°C. At 30‐min reaction time, the graft yield at 50°C was not more than 70% of the corresponding value at 30°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Temperature and crystallinity profiles generated in a polycaprolactone/starch blend under different cooling conditions

This work concerns the numerical simulation of the temperature profiles and the degree of crystallinity through the thickness of a part made from a commercial biodegradable material based on caprolactone and starch (Mater‐Bi Z), as a function of the cooling conditions from the melt. The crystallization kinetics during cooling conditions was evaluated experimentally by calorimetry and the Kamal–Chu equation was used to describe the degree of crystallinity developed during constant cooling rate experiments. This equation coupled with the thermal energy equation, through a heat source term, described the heat generated during crystallization of the polymer. The numerical solution of the system of differential equations was obtained using an implicit finite‐difference method. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3275–3283, 2001