Preparation and properties of partially hydrolyzed cross-linked guar gum

There has been a growing interest in the modification of guar gum to improve its properties and enlarge its application. The aim of this study was to prepare partially hydrolyzed cross-linked guar gum with a composite modification method, based on guar gum, hydrochloric acid, epichlorohydrin and solvent. To obtain a product with suitable properties for other fields, the effects of various factors such as reaction time, reaction temperature, pH, the amount of ethanol and cross-linking agent on the cross-linking degree of partially hydrolyzed cross-linked guar gum were studied. The stability of the hot paste viscosity, cold paste viscosity, acid resistance, alkali resistance, retrogradation, freeze–thaw stability and swelling power were determined. The product was characterized by differential scanning calorimetry. The sedimentation volume method was selected to determine the cross-linking degree of the product. The best conditions for preparing partially hydrolyzed cross-linked guar gum were: reaction temperature 50 °C, reaction time 4 h, the amount of ethanol 58 %, pH 10.5. After guar gum was modified by acid, or cross-linked by epichlorohydrin, its freeze–thaw stability and expansion capability decreased, but its acid resistance, alkali resistance, cold paste stability and hot paste viscosity stability were improved.     

Shear-thinning and viscosity synergism in mixed solution of guar gum and its etherified derivatives

The flow properties of mixed solution of guar gum and carboxymethyl guar gum, including shear-thinning and viscosity synergism, have been studied at different mixed ratios, shear rates and temperatures using rheometer. The results show that addition of carboxymethyl guar gum enhances shear-thinning behavior and increases viscosity in guar gum solution at a given range of mixed ratios. The temperature-dependence of the mixed solution is markedly different from a single solution. The activation energy of blends with 50 and 75% of guar gum were determined to be 11.02 and 10.39 kJ mol⁻¹, respectively, lower than that of a single solution. These results indicate that the network structure of viscous solution has been changed because carboxymethyl groups branched in galactomannans had changed the interaction among macromolecular chains.     

Morphology and rheological properties of polypropylene-linear low density polyethylene blends

The dynamic shear viscosity and the morphology of polypropylene homopolymer and copolymer blended with linear low density polyethylene are studied. A maximum in the dynamic shear viscosity vs. blend composition is reported for the polypropylene copolymer, linear low density polyethylene system. The increasing dynamic shear viscosity is in accordance with the occurrence of a morphology of polyethylene inclusions in rubber surrounded by a polypropylene matrix. Comparing calculations of the dynamic shear viscosities—based on a shell model with interlayer—and experimental results supports this view.     

水泥助磨剂助磨效果的研究

试验选用常用的助磨剂A(丙三醇)、B、D三种不同的助磨剂,从水泥的45μm筛筛余、比表面积、均匀性系数n、标准稠度用水量4个指标分别来评价三种助磨剂的助磨效果。结果表明,助磨剂的助磨效果可以通过水泥的45μm筛筛余、比表面积、均匀性系数n进行表征,而用标准稠度用水量来评定效果不理想。     

Pan‐milling to prepare ultrafine high‐density polyethylene powder with sodium chloride serving as grinding aid

In this article, our self‐designed pan mill equipment was used to pulverize high‐density polyethylene (HDPE) to prepare its powder product. This pan mill based on three‐dimensional shear forces shows much better pulverization effects on ductile polymer materials when compared with conventional pulverizing equipment based on impact force, and it can mill original HDPE pellets (particle size: 3–4 mm) into fine powder (particle size: 75 μm) at ambient temperature. To further improve the pulverization efficiency to obtain ultrafine HDPE powder, sodium chloride (NaCl), serving as a grinding aid, was comilled with HDPE. Taking the advantages of the cutting and isolating effects of NaCl crystals, HDPE can be pulverized into ultrafine powder with the particle size below 10 μm. Another advantage of NaCl as a grinding aid lies in an easy removal process through water wash, thus conveniently separating from hydrophobic HDPE powder. This technology provides a novel and efficient method to prepare the ultrafine powder of those polymers with high ductility and low melt point, and shows a promise in future commercial application. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Expansion-contraction behavior of dilute polymer solutions

Expansion-contraction behavior of capillary jets of dilute polymer solutions has been studied by using small diameter capillary tubes. The test liquids were water, glycerine solution and dilute solutions of polyethylene oxide and guar gum. It has been found that polyethylene oxide molecules degraded considerably at high shear rates; however the molecular degradation had little effect on the observed expansion-contraction behavior of capillary jets. On the other hand, the solvent viscosity had an appreciable effect on the issuing jets and on the final magnitude of the evaluated normal stresses     

Dietary Guar Gum Reduces Lymph Flow and Diminishes Lipid Transport in Thoracic Duct-Cannulated Rats

Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV), and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid transport by means of its physicochemical properties related to water behavior in the intestine.     

Research on the viscosity-increasing mechanism and performance analysis of modified polysaccharide natural polymer fracturing fluid gel

In this paper, a guar gum-based hydraulic fracturing fluid suitable for low permeability oil and gas reservoirs was prepared using alkylamine guar gum (J580) as a thickening agent. The viscosification mechanism and comprehensive properties were analyzed to provide theoretical support for improving the fracturing fluid utilization rate and oil and gas field development in Changqing Oilfield. In this experiment, the properties and microstructure of thickener J580 were analyzed by infrared spectroscopy (FT-IR), nuclear magnetic resonance (¹H-NMR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The rheometer, dynamic filtration device, and acid erosion fracture conductive ability device were used to study the temperature and shear resistance performance, viscoelastic properties, dynamic filtration performance, and fracture conductive ability damage of the system. the gel breaking performance, formation water compatibility, and anti-swelling performance of the system were measured according to the standard. The results show that J580 is an amine modified product of guar gum, and its viscosity increasing mechanism is similar to that of guar gum. The breaking time of the system is 375 s, the residue content is 413 mg/L, and the surface tension is 26.49 mN/m. At 90°C, the viscosity of the solution can be maintained at 180 mPa · s, loss modulus G" dominates, the anti-swelling rate is 82.5%, the damage rate of the conductive ability is 22.40%, and the dynamic filtration coefficient is 1.3 × 10⁻⁵ m/s^1/2. The fracturing fluid system has good dynamic filtration performance, conductive ability, temperature and shear resistance, good structural strength, can easily break glue and return, and less residue content.     

Highly toughened polylactide by renewable Eucommia ulmoides gum

Polylactide (PLA) derived from natural sources has attracted increasing interest and has provided a promising alternative to traditional plastics derived from petroleum sources. With no loss of environmental friendly features, PLA was highly toughened by Eucommia ulmoides gum (EUG) derived from Eucommia ulmoides oliv. The dynamic mechanical analysis, scanning electron microscopy (SEM), and differential scanning calorimetry results show that the PLA–EUG blends were immiscible systems. SEM micrographs revealed that EUG particles were well dispersed in the PLA matrix with number‐average particle diameters of 2–4 μm. The mechanical properties indicated that the tensile strength decreased with increasing EUG contents, but the elongation at break and the impact strength were enhanced. The notched impact strength of the blends improved by 5.9‐fold compared to that of neat PLA. The PLA–EUG blends exhibited distinct shear‐thinning behavior; this indicated good processability, and the storage modulus and loss modulus of the PLA–EUG blends increased with EUG content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46017.     

Mechanical properties,crystallization characteristics,and foaming behavior of polytetrafluoroethylene‐reinforced poly(lactic acid) composites

In this study, poly(lactic acid) (PLA)/polytetrafluoroethylene (PTFE) composites containing different amounts of PTFE were prepared by melt blending. The mechanical, crystallization, and foaming properties of the prepared composites were investigated. Tensile test results indicated that the mechanical properties of the composite with PTFE showed significant reinforcement and toughening effects. The average elongation‐at‐break of the composite increased by 72% compared with pure PLA. Scanning electron microscopy (SEM) showed that the PTFE elongated into fibrils during blending and formed a physical network of entanglements in the melt. Differential scanning calorimetry (DSC) also showed that PTFE had a significant nucleation effect on polymer crystals and greatly increased the crystallinity of the PLA matrix. Moreover, PTFE dramatically enhanced the melt viscosity of PLA, which was investigated by rheological tests. The injection molding foaming experiments revealed that adding 1 wt% PTFE had the most notable heterogeneous nucleation effect on foamed cells, with the cell size decreasing from 81.5 μm for neat PLA to 25.2 μm, and the cell density increasing from 1.34 × 10⁸ cells/cm³ to 2.53 × 10⁹ cells/cm³. POLYM. ENG. SCI., 57:570–580, 2017. © 2016 Society of Plastics Engineers     

Intensive grinding of powders in an electro-magneto-mechanical mill

The paper presents the results of high-energy grinding in the electro-magneto-mechanical (EMM) mill. Ground powder is treated in a very specific and intensive way owing to several field forces operating simultaneously in the EMM mill. The grinding power in the centre of the mill's working chamber is in the order of 2 MW/m³, which is much more than in ordinary mills. Therefore, the grinding time is very short, i.e., several tens of seconds. The self-disintegrated Fe–Al–Si powders of 155 μm on average undergo size reduction to 8 μm after 120 s. Over 25% of the total weight get the size of less than 1.3 μm. Very hard materials, such as SiC and B₄C reduce their grain size over 30 times after 120 s of grinding in the EMM mill. The results of the grinding of Fe₂O₃ powder are even better. In ball mills, vibration and planetary mills, similar results can be achieved after a period several hundreds times longer. The treatment of Fe–Al–Si powder presented here is intended as the preparation procedure for sintering, plasma spraying or laser surface alloying.     

瓜尔胶的化学改性

简要介绍了瓜尔胶的结构及其化学改性的原理和方法；综述了国内外瓜尔胶化学改性的研究工作；详细介绍了非离子瓜尔胶、阳离子瓜尔胶、阴离子瓜尔胶、羟烷基阴离子瓜尔胶和羟烷基阳离子瓜尔胶以及两性瓜尔胶的合成方法。瓜尔胶通过改性改善了水溶性、大大降低了水不溶物的含量、提高了电解质的兼容性、增加了黏度的稳定性、从而扩大了瓜尔胶的应用领域，使得改性瓜尔胶广泛应用于化妆品、个人护理品、造纸、油田和增稠剂等众多领域。     

A novel route for synthesis of cross-linked polystyrene copolymer beads with tunable porosity using guar and xanthan gums from bioresources as alternative synthetic suspension stabilizers

Cross-linked polymer beads with different cross-linking agent loading were prepared by carrying out cross-linking suspension copolymerization of styrene-divinylbenzene (St- DVB) monomers using guar gum (GG) and xanthan gum (XG) from bioresources as eco-friendly suspension biopolymer stabilizers in the presence of non reactive diluents. The effects of GG and XG as suspension biostabilizers on the characteristics of the styrene copolymer beads were investigated regarding thermal properties, porosity characteristics, solvent swelling ratio, and surface morphologies using TGA, DSC, XRD, SEM, BET analyses. Spherical and regular beads with smooth surface were produced and the average particle size was in the range 170–290 μm (50–80 mesh size). The porosity characteristics of the produced beads including surface area and pore volume were in range 0.45 m²/g and 32–45 ml/g, respectively. Overall, the present article provided a novel route to prepare cross-linked polystyrene copolymer beads with tunable porosity suitable for catalyst support.     

Synthesis and characterization of acryloyloxy guar gum

Guar gum is a galactomannan commonly used as a viscosity modifier in the food, pharmaceutical, and cosmetics industry. The aim of this study was to synthesize acryloyloxy guar gum via a Schotten‐Bauman reaction in aqueous media. The reaction products were characterized using FTIR, C¹³‐NMR, wide angle X‐ray diffraction techniques to ascertain the effect of acrylation on the structure of guar gum. The acrylation of guar gum was found to be limited to the primary hydroxyl groups on the guar gum molecule. The maximum degree of substitution (DS) was found to be 0.56, which was observed after 3 h of reaction. Since the reaction was carried out in an aqueous medium after 3 h of reaction the DS of the derivatised guar gum was found to decrease, because of hydrolysis of the formed ester linkages. The ester content and intrinsic viscosity of the derivatised guar gums were also evaluated. Thermal analysis showed that a higher DS resulted in products with lower thermal stability and there was no evidence of reaction via the acrylate groups on heating. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

微生物含量对瓜尔胶水溶液黏度的影响研究

对(不同微生物含量)瓜尔胶粉水溶液的黏度随时间而降低的规律、杀菌剂的种类和用量对抑制胶液黏度降低的效果进行了研究。结果表明:瓜尔胶中含有的微生物会导致其水溶液久置后黏度降低,瓜尔胶水溶液放置时间越长(或微生物含量越高),黏度降低幅度越大;当w(D581杀菌剂)=0.3%时(相对于瓜尔胶粉质量而言),其抑制微生物生长的效果较好,表现为48 h内胶液(微生物含量为6×104 CFU/g)黏度降幅较低(仅为0.5%)。     

阳离子羟乙基瓜尔胶的合成及其造纸湿部应用

对一步泥浆法合成新型助留助滤剂———阳离子羟乙基瓜尔胶(CEG),及将其用于废新闻纸浆的抄造过程进行了探讨。悬浮于醇/水体系中的瓜尔胶,先与阳离子单体发生醚化反应,然后与氯乙醇在微过量碱催化剂存在下进行羟乙基化反应,阳离子中间产物不必分离。重点研究了阳离子醚化产物的黏度及氮质量分数的影响因素,确定了阳离子化反应优化条件为:m(阳离子单体)∶m(瓜尔胶)=0.4∶1,m(NaOH)∶m(瓜尔胶)=0.25∶1,反应温度60℃,反应时间2.5 h。经红外光谱分析,证实了接枝产物中季铵阳离子基团的存在。由于CEG分子结构同时含有季铵阳离子和非离子的活性羟基,CEG常温水合作用进一步强化,w(CEG)=1%的水溶液的透光率增加到80%。当以w(CEG)=0.2%(以绝干浆计)的用量添加到废新闻纸浆中,细小组分的单程留着率提高了40%,打浆度减少了37%。     

Three‐dimensionally printed bioinspired superhydrophobic PLA membrane for oil‐water separation

A novel lotus‐leaf‐inspired superhydrophobic poly(lactic acid) (PLA) porous membrane was fabricated for oil‐water separation based on fused deposition modeling three‐dimensional printing and subsequent chemical etching and the decoration of polystyrene nanospheres. A superhydrophobic PLA fractal surface with a water contact angle of 151.7° and low water adhesion force of 21.8 μN was achieved. The membrane pore size could be easily adjusted from 40 to 600 μm via a computer‐aided design program to optimize separation performance. The maximal oil‐water separation efficiency of 99.4% was achieved with a pore size of 250 μm, which also exhibited a high flux of 60 kL m^?2 h^?1. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3700–3708, 2018     

水性多彩涂料的研发及应用

采用天然高分子瓜尔胶为凝胶物质,制备了水性多彩涂料.通过实验发现,高黏度瓜尔胶形成的有色凝胶粒子比低黏度瓜尔胶形成的有色凝胶粒子稳定性好;玻璃化转变温度低的树脂乳液有利于本体系凝胶粒子对色浆的包裹.通过对比,筛选出了3种牌号瓜尔胶和乳液,制得具有良好装饰效果的水性多彩涂料.     

Carboxymethyl guar: Its synthesis and macromolecular characterization

Guar gum was partially carboxymethylated by the reaction of the base polysaccharide with the sodium salt of monochloroacetic acid in presence of sodium hydroxide. The resulting products (carboxymethyl guar with different degrees of substitution) were characterized by a variety of material characterization techniques, such as intrinsic viscosity measurement, determination of molecular weight, elemental analysis, thermal analysis, ¹³C‐NMR spectra, and Fourier transform infrared analysis. Various grades of carboxymethyl guar gum, which were synthesized in the laboratory, were studied for their suitability as flocculants and viscosifiers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of graft copolymer (guar gum–g–N‐vinyl‐2‐pyrrolidone) and investigation of metal ion sorption and swelling behavior

Graft copolymer of N‐vinyl‐2‐pyrrolidone with guar gum was synthesized and its reaction conditions were optimized for better yield using potassium peroxymonosulfate (PMS) and glycolic acid (GA) as a redox initiator. The effect of PMS, GA, hydrogen ions, guar gum, and N‐vinyl‐2‐pyrrolidone (NVP) along with reaction time and temperature were studied by determining the grafting parameters: grafting ratio, efficiency, conversion, add‐on, homopolymer, and rate of grafting. It was observed that the maximum yield occurred at with a time of 120 min at a temperature of 45°C and a guar gum concentration of 0.4 g/L concentration. The graft copolymer was characterized by infrared spectroscopy and thermal analysis. The activation energy for the grafted and ungrafted gum was calculated. It was observed that the graft copolymer was thermally more stable than the pure gum. The swelling and metal ion sorption behavior of guar gum and guar gum‐g‐N‐vinyl‐2‐pyrrolidone also were studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2480–2489, 2006