高粘度羧甲基淀粉醚的研制

介绍了由玉米淀粉作为原料制取羧甲基淀粉醚的方法。着重讨论了该产品的配方设计，并对产品的各项性能进行了检验。     

Margarines: A rheological study

Time-dependent flow properties of both commercial and pilot plant-made margarines were characterized under steady shear. Flow curves were fitted to the kinetic expression τ = τ _i +a e ^−k1t +b e ^−k2t . A first-order kinetic model did not describe the observed destruction process of the margarine structure in an adequate manner. In the proposed model, two structures with different destruction rates are postulated. Each structure contributes to a part of the shear stress necessary to deform the margarine sample. The parameters τ _i a andb are temperature-dependent. Decreasing temperatures produce an exponential increase of τ _i , a linear increase ofb and an increase ofa up to a point beyond which it remains constant. A physical interpretation of the model is proposed. The role of the aqueous phase was also studied. Greater hardness was detected at higher water content. Parameter τ _i increased, at any selected temperature, with increasing aqueous phase content of the sample. Parametera increased with decreasing temperatures and higher water content. On the other hand, parameterb was not affected by the amount of aqueous phase. This kinetic model could be employed to perform studies on the influence of different parameters of margarine formulation on its rheologic behavior.     

Carboxymethyl sago pulp/carboxymethyl sago starch hydrogel: Effect of polymer mixing ratio and study of controlled drug release

Carboxymethyl sag o pulp (CMSP)/carboxymethyl sago starch (CMSS) hydrogel was synthesized by electron beam irradiation. In the series of hydrogels prepared, 40%/20% CMSP/CMSS hydrogel had the highest gel fraction. The swelling capacity of CMSP/CMSS hydrogel was found to be highest in distilled water, followed by pH 11, pH 7.4, and pH 1.2. Scanning Electron Microscope photographs revealed that the drug‐loaded hydrogel had a smoother surface than unloaded hydrogel. Fourier Transform Infrared and Differential Scanning Calorimetry analysis showed the absence of interaction between the hydrogels and the drug. All drug‐loaded hydrogels had drug encapsulation efficiency between 63% and 69%. CMSP/CMSS hydrogel swelled and allowed the release of drug at pH 7.4. These properties qualify the hydrogel as a potential candidate for controlled drug release at the ocular and colonic regions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43652.     

A rheological study of aqueous separan solutions

The concentration dependence of the rheological response of aqueous Separan solutions was measured. The shear and primary normal stress response in steady shearing flow, and the relaxation of shear stress following cessation of steady shear flow, were measured with four different polymer solution concentrations. Two different nonlinear constitutive equations, Bird-Carreau and Meister, were used to analyse the data. The Bird-Carreau model fit the steady shear data very well and the parameters obtained from steady shear data allow reasonable estimates of the stress relaxation of these systems. The Meister model provided a fit of the transient stress relaxation data and could be used to estimate the steady shear response. No quantitative molecular theory was developed in this work. However, the nature of the concentration dependence of the Bird-Carreau parameters suggests that as the polymer concentration of aqueous Separan solutions decreases from 2.0 to 0.05 weight percent the solutions should be modeled less by an entangled network theory and more as slightly overlapping hydrodynamic units. The concentration where this behavior seems to be changing appears to be about 0.25 percent by weight of polymer.     

Chemical modification of starch (III). Improved rheological properties of starch through aqueous cyanoethylation

Cyanoethylated starch containing 4.53 wt.-% nitrogen was prepared by reacting starch with acrylonitrile in aqueous medium under the catalytic influence of sodium hydroxide. Rheological properties of cyanoethylated starch were examined and compared with those of alkali treated starch before and after storing for varying lengths of time. Cyanoethylated starch offered advantages in terms of higher stability to storage, higher apparent viscosity and improved film-forming properties as compared with alkali treated starch.     

Structure/rheological properties relations of crosslinked potato starch suspensions

Some rheological properties of aqueous suspensions of crosslinked hydroxypropylated potato starches were investigated. The crosslinking was performed at a temperature above the gelatinization temperature and the degree of crosslinking varied between 0.05 and 0.75% wt. The samples were characterized by the swelling power Q and the average particle size D and observed by light microscopy and low‐temperature SEM. The swelling power decreases with the extent of crosslinking, whereas the average particle size increases. From these observations, the starch samples can be described as suspensions of deformable particles suspended in a continuous suspending medium constituted of polymer chains plus water. The rheological properties allow us to define different concentration regimes depending on the close packing of swollen particles at a concentration C*, which is close to 1/Q. In dilute conditions, that is, for C < C*, the viscosity is little influenced by the degree of crosslinking and, hence, by the particle size. Two domains can be defined: a “true dilute” one for C < 0.6C* and a semidilute one for C > 0.6C*, in which the viscosity rapidly increases with the concentration. Moreover, an apparent yield stress and elastic properties are observed in the concentrated regime, for C > C*. Two domains can be also defined: a first one for C < 2C*, in which the rheological characteristics sharply increase with the concentration, and a second one, a quasi‐plateau domain, for C > 2C*. The variations of these rheological properties suggest that the rigidity of the swollen particles can be considered, contrary to the viscosity in the true dilute regime. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2480–2489, 2001     

Dynamic rheological properties of Yam starch/hectorite composite gels

The rheological properties of composite gels of starch extracted from Yam roots (Discorea sp) and hectorite (a mineral clay belonging to the smectite group) were studied in aqueous solutions as a function of hectorite concentration. The elastic (G′) and viscous (G″) moduli of the composite gels were dependent on the clay content, and for all samples G′ was greater than G″. Composite gels with clay contents of <30% presented higher G′, G″ and viscosities |η*| when compared with pure starch gel, while those with a content of 50 % showed lower values. The addition of hectorite significantly inhibited the creeping properties in relation to pure starch at 25 °C but, after heating/cooling cycles between 25 and 85 °C, this effect was not observed and the composite gel showed similar behavior to that of pure starch. Copyright © 2005 Society of Chemical Industry     

A rheological and morphological study of treated PVC

This article reports a rheological and morphological study of poly(vinyl chloride) (PVC) that was subjected to a treatment capable of decreasing the simultaneous mass transfers occurring between liquid food (or simulant) and PVC packaging. The storage modulus (G′), loss modulus (G″), and the loss angle (tan δ), have been used to determine the glass transition temperature using a Rheometric Scientific Dynamic Analyzer. Young's modulus was measured on a dynamometer, and a morphological characterization was carried out with an optical microscope. The obtained results show that treated PVC behaves like a composite material, which is in agreement with a previously established model. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3497–3502, 2003     

A rheological study of concentrated aqueous nanotube dispersions

The rheological behaviour of aqueously dispersed oxidised nanotubes has been studied at concentrations at which the nanotubes interacted with each other. The dispersed nanotubes represented a high aspect ratio system with a ratio of 80. Dynamic and steady shear tests were applied to the dispersions using a cone and plate rheometer. The system was found to behave as a reversibly flocculated dispersion. The structure of the dispersions was highly strain-sensitive with the linear viscoelastic region (LVR) extending to strains of 1%. The moduli within the LVR were independent of frequency and scaled with concentration by a power law. Under steady shear the dispersions rapidly shear thinned up to a Peclet number of 1 to 10. At higher Peclet numbers the shear thinning behaviour followed the Ostwald–de Waele power law. The dispersions were thixotropic and recovered their structure, and hence viscosity, upon standing.     

PVA/淀粉共混物的动态流变行为和相转变

用复合增塑剂在哈克流变仪上制备了热塑性聚乙烯醇(PVA)/淀粉共混物,研究了共混体系的动态流变行为,观察了共混物的微观结构.结果表明: PVA/淀粉共混物熔体的动态流动行为与其组分的熔体类似,都表现为类固态行为,显示出假塑性流体的流动特征; PVA/淀粉熔体随着组成的变化存在一次相逆转,其复数黏度、储能模量和损耗模量均随着淀粉含量的变化出现了正-负偏差,这说明共混体系出现了相转变,转变点在淀粉质量分数为80% 处.     

Effects of sucrose on the rheological behavior of wheat starch pastes

The rheological properties of starch–water–sucrose pastes have been determined under steady and oscillatory shear conditions. The results show that the effect of sucrose at concentrations of less than about 20% w/w is to increase the apparent viscosity, yield stress, dynamic viscosity, and dynamic rigidity. At higher surose concentrations the yield stress and dynamic rigidity tend to zero while values of the dynamic viscosity and apparent viscosity are reduced compared with controls. Sucrose causes the dispersed gel particles in pastes to change volume, and it is suggested that this is one of the factors responsible for the observed effects of sucrose on rheological behavior.     

Intumescent flame retardant polyurethane/starch composites: Thermal,mechanical, and rheological properties

Intumescent flame retardant polyurethane/starch (IFRPU/starch) composites were prepared by means of melt blending. Microencapsulated ammonium polyphosphate (MCAPP) was added to improve its compatibility with matrix, retardation of reaction between acid and carbon source, and its water resistancy. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of hydrogen bonding and entangled network between IFR system and PU matrix. Further, scanning electron microscopy (SEM) illustrated homogeneity of starch in matrix. By addition of 10 wt % of starch and 20 wt % of IFR, limiting oxygen index (LOI) increased from 22.0 to 40.0 and UL94 V0 rating was achieved. Differential scanning calorimetry (DSC) detected three endothermic transitions and one glass transition (T_g). The temperature of transition III and T_g increased with starch due to crosslinking between PU and starch. The improved thermal stability in the presence of starch was confirmed by thermogravimetric analysis (TGA). Beside the fact that starch was used as a carbonization agent to improve flame retardancy, it also effectively led to enhanced mechanical and viscoelastic properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41158.     

A structure rheological study with poly (oxyethylene)

Four samples of poly(oxyethylene) dissolved in water have been studied rheologically. Flow curves have been obtained for different molecular mass and concentration. From no the mass of network strand, the apparent chain element and the penetration hindrance have been obtained. The polymer turns out to form in water entanglement network solutions with somewhat hindered penetration.     

A rheological study of the gelling of UF polycondensates

The gelling process of urea–formaldehyde resins has been investigated by rheological methods. The gel point values were determined by three methods, and compared with those obtained by low resolution impulsional ¹H‐nuclear magnetic resonance. The activation energy of the curing process was determined and the effect of the molar ratio was investigated. In addition, the critical power exponents were calculated and the parameters of the relaxation modulus function were also determined. Equations describing the gel time as a function of degree of conversion and reactants molar ratio are presented. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1296–1302, 2000     

ABA low molar mass triblock copolymers in reverse emulsions: A rheological study

The effect of blocks length and molar mass of ABA triblock copolymers on the rheological behavior of water in oil (w/o) emulsions was investigated. Emulsion parameters such as water droplet concentration (and droplet size) of a series of inverted emulsion systems were evaluated. All copolymer/emulsion systems studied showed a non-Newtonian behavior, and the presence of the copolymer in the emulsion system led to an increase of the low shear viscosity when the size of the midblock of the copolymer was in a specific size range. This suggests the formation of a transient network through the interconnection, by the copolymer, of the smaller water droplets present in the emulsion. Consequently, the systems behave as w/o emulsions containing reversibly crosslinked oil-soluble polymers in the continuous phase, resulting in a pronounced shear thinning behavior. For the different emulsions studied, the relative viscosity increased, with few exceptions, with increasing droplet concentration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

羧甲基纤维素的制备研究

本文报告了由纤维素——麻毛为原料制备羧甲基纤维素(CMC)的方法,得到了制备羧甲基纤维素的最佳条件,并讨论了各项因素对结果的影响。     

Carboxymethyl inulin: A new inhibitor for calcium carbonate precipitation

A new polysaccharide-based polycarboxylate, carboxymethyl inulin (CMI), was synthesized recently. The influence of small amounts (0.1–200 ppm) of this material on the crystallization of calcium carbonate, an important scale-forming salt, is studied. The effects of CMI are compared to those of a commercial inhibitor (a copolymer of acrylate and maleate) and of other carboxymethylated saccharides. It is shown that CMI is a good calcium carbonate precipitation inhibitor. CMI influences the spontaneous precipitation of calcium carbonate, the morphology of the formed crystals (vaterite and calcite), and the growth rate of calcium carbonate seed crystals. The effect is related to the carboxylate content, the chainlength, and the concentration of the additive. For the application of CMI as crystallization inhibitor, products with a high degree of substitution (degree of substitution>1) and a high degree of polymerization (average degree of polymerization = 30) are the most effective. Also, other carboxymethylated polysaccharides (dextrins, cellulose) show good crystallization-inhibition properties, although the performance of the copolymer of acrylate and maleate is not met. A great advantage of CMI, as compared to carboxymethyl cellulose (CMC), is that aqueous solutions of CMI display, contrary to those of CMC, a very low viscosity. A carboxymethylated disaccharide (carboxymethyl sucrose) has no influence on the calcium carbonate crystallization which shows that the long-chain character is essential for a polycarboxylate inhibitor.     

应用光相关谱方法研究在电解质溶液中羧甲基淀粉和聚丙烯酸共聚物分子的构象

本文应用光相关谱（PCS）的方法研究了在不同的电解质溶液中羧甲基淀粉（CMS）,交联聚丙烯酸钠盐（PAS）和交联聚丙烯酸-聚丙烯酸胺（PAA）共聚物铵盐构象的变化。实验结果表明,在氢氧化钠水溶液和氯化钠水溶液中,随着电解质浓度的增加,溶液的电导率也有较大幅度的增加,聚合物PAS和PAA的水力半径则呈下降趋势,而CMS的变化是不同的。在氯化钠溶液中,CMS的水力半径基本上无大的变化。在氢氧化钠溶液中当氢氧化钠浓度达到0.5％时,水力半径开始下降。在醋酸溶液中,三种聚合物的水力半径,不受电解质浓度变化的影响。同时发现,在表观粘度相同时,在相同的电解质浓度下,CMS的水力半径均大于PAS和PAA,只有在高氢氧化钠浓度时除外。     

A structure rheological study of cellulose trinitrate in ethyl acetate

A structure rheological analysis was undertaken with cellulose trinitrates dissolved in ethyl acetate. Empirical scaling laws with molecular mass and concentration were found for the zero shear viscosity η_o and the critical shear rate $ \dot \gamma _C $ at the onset of shear thinning. Values for the apparent chain element A' were calculated from the concentration dependent network strand M_e and extrapolated to zero concentration. They were compared with dilute solution data. From the concentration dependence of the mass of network strand M_e a network with hindered penetration was inferred.     

A study on the rheological properties and processability of polycarbonate

The transport theory for the solids conveying zone in a single‐screw extruder was applied to calculate the pressure distributions along the screw channel for several bisphenol A polycarbonate resins based on the screw revolution speed and the flow rate. The pressure distributions and the flow rates of the resins were related to the structural and rheological properties. When polymers have the same chemical structure and number‐average molecular weight and the same mechanical properties, the polymer having a broader molecular weight distribution showed a lower glass transition temperature. For the polymer with broader MWD a relatively low pressure was developed along the screw channel, and an increased flow rate was observed. A relatively short melting length was also observed for this polymer and, accordingly, it was concluded that the polymer with a broader MWD has a better processability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2921–2929, 2002