可得然胶凝胶特性改变的研究

研究了添加两种盐类（PS、NS）对可得然胶凝胶强度的影响。结果表明,PS能够显著增强可得然胶在高温状态时的凝胶强度;NS能够显著降低可得然胶的凝胶初始温度;NS与PS复配,其协同作用可大幅提高可得然胶的凝胶强度、降低可得然胶的使用浓度和凝胶初始温度,从而拓展其应用范围。一     

可得然胶凝胶高温稳定性的改进

为了扩展可得然胶在三次采油等领域的应用,通过单因素实验与正交实验研究了提高可得然胶凝胶高温稳定性的方法。结果表明:添加适量的韦兰胶(0.15%)、小核菌多糖(0.15%)、四硼酸钠(2.00%)及Na_2SO_3(0.3%)能够显著提高可得然胶凝胶(2%含量)在高温(100℃)条件下的稳定性,保温60 d,凝胶强度保留率达到75%以上,凝胶脱水率低于15%,提高稳定性效果理想,为可得然胶后续深入拓展开发提供了实验数据。     

可得然胶功能特性及在肉及肉制品中的应用进展

可得然胶是一种微生物胞外多糖,因其良好的增稠、持水、凝胶以及成膜等性能,近些年在肉类加工及保鲜领域得到了广泛的应用。该文综述了可得然胶的功能特性,重点阐述了可得然胶对肉及肉制品品质特性的影响及其对肉品的品质提升机制,最后总结了由可得然胶制备的不同类型可食性复合膜在肉类保鲜中的应用效果,以期为可得然胶在肉类加工和保鲜领域的广泛应用提供理论参考。     

耐高温凝胶调剖体系成胶性能影响因素研究

通过优化聚合物及交联剂类型及比例，研究对凝胶体系成胶性能及耐温耐盐性能的影响，研制出了适用于高温高盐油藏的凝胶调剖体系，并获得了主要性能指标。实验结果表明，所研究的高温凝胶体系在温度140℃、矿化度50 000 mg·L^-1条件下，成胶强度高、稳定性好且脱水率低，满足海上油田调剖技术的应用需求。     

腐植酸-水玻璃复合凝胶制备及性能评价

针对塔河油田油藏储层深且高温、高盐的储藏条件,目前无机硅酸盐水玻璃凝胶易高温老化脱水,使得封堵效果变差。鉴于此,亟需研发一种在高温、高矿化度条件下具有老化稳定性好、强度高和封堵性能好的凝胶堵剂。制备了有机-无机复合凝胶,采用成本低廉的工业腐植酸与水玻璃复合,尿素做延迟交联剂,制备了腐植酸-水玻璃复合凝胶,以基液粘度、pH、成胶时间、成胶强度和高温老化稳定性为依据优选最优配方,以注入性能和封堵性能评价凝胶封堵效果。结果表明,最佳配方3%腐植酸+3%尿素+20%水玻璃,基液粘度14.2 mPa·s, pH为11.68,在130℃条件下,成胶时间90～120 min,成胶强度为0.07 MPa, 30 d内不脱水,具有较好的注入性和封堵性。在单管填砂管中注入0.5 PV该体系后,1 100 mD渗透率填砂管的封堵率大于90%。     

高温养护对炉底灰胶凝体系强度及水化产物的影响

为实现炉底灰在大体积混凝土工程中的资源化利用,结合净浆强度测定、X射线衍射、红外光谱及扫描电镜等手段,研究了高温养护对不同龄期炉底灰胶凝体系强度及水化产物的影响,结果表明:炉底灰胶凝体系水化产物主要为羟钙石,红辉沸石,文石以及C-S-H凝胶,高温养护促进了胶凝体系中硅酸钙的水化,生成更多的羟钙石和C-S-H凝胶,提高了试样早期强度;养护后期,胶凝体系水化速率及强度增长速率减小,羟钙石参与碱激发反应被消耗,C-S-H凝胶聚合度降低.高温养护下,胶凝试样的早期微观形貌以密实的网状C-S-H凝胶为主,随着龄期的增长,C-S-H凝胶结构更加致密,包裹于凝胶中的羟钙石在高温作用下产生微裂隙,阻碍了试样强度的发展.     

甘蔗渣微晶纤维素特性及其对可得然胶溶液流变特性的影响

为丰富甘蔗渣的综合利用,提高综合产业价值,采用酸解法制备甘蔗渣微晶纤维素,分析甘蔗渣微晶纤维素理化性质及结构,构建甘蔗渣微晶纤维素/可得然胶混合液体系,研究甘蔗渣微晶纤维素对可得然胶溶液流变特性的影响。结果表明,甘蔗渣微晶纤维素聚合度为143,持水力7.55,直径约为10μm,熔融温度为169.5℃,FTIR、XRD分析表明其保留了纤维素基本化学结构。甘蔗渣微晶纤维素能增强可得然胶溶液,在扫描范围内,G′>G″,其流变表现为典型的弱凝胶特性,表明甘蔗渣微晶纤维素在可得然胶溶液中分散性良好,有助于增强溶液体系网络结构,溶液稳定性良好。     

腐植酸-有机凝胶的制备及性能评价

针对塔河油田油藏储层深且高温、高盐的储藏条件,目前普通聚丙酰胺易高温老化脱水,使得封堵效果变差。鉴于此,亟需研发一种在高温、高矿化度条件下具有老化稳定性好、强度高和封堵性能好的凝胶堵剂。采用成本低廉的工业腐植酸为增强剂和稳定剂,耐温耐盐的含有磺酸基团的聚丙烯酰胺为主剂,六亚甲基四胺、对苯二酚作延迟交联剂,制备了腐植酸-有机凝胶,以成胶时间、成胶强度和高温老化稳定性为依据优选最优配方,以对填砂管凝胶固化后突破压力作为封堵性能评价凝胶封堵效果。结果表明,最佳配方2%腐植酸+0.6%六亚甲基四胺+0.6%对苯二酚+0.5%SV-2+0.8%SV-5,在130℃条件下,成胶时间4 h,成胶强度为16 Pa, 30 d内脱水低于10%。在单管填砂管中注入35 mL凝胶基液后,该体系固化后,突破压力达0.86 MPa,突破后经过4倍于凝胶基液的水冲刷,依然具有0.12 MPa压力,表明该凝胶具有较好的封堵效果和较好粘壁性。     

江蓠漂白液清洗方法对提取琼胶的影响研究

针对江蓠琼胶加工过程中漂白液清洗不当造成的质量不稳定问题,探讨了清洗方式与江蓠、提胶率和凝胶强度的因应关系,提出了反冲和喷淋相结合的清洗方法,研究结果表明,采用这一方法,在其他工艺条件相同的情况下,可以显著提高提胶率和产品凝胶强度。     

γ-聚谷氨酸/可得然胶共混膜的制备研究

本研究的目的是制备一种可以生物医用的新型材料。以可得然胶和γ-聚谷氨酸为原料,通过溶液共混法制备可得然胶/γ-聚谷氨酸共混吸水膜材料。产物用吸水率测试和力学性能测试等方法对共混膜进行了表征。结果显示,当可得然胶与γ-PGA质量比为2∶1,反应温度为50℃,交联剂为季戊四醇时,共混膜的各项性能达到最佳,其吸水率为1200,透气性为152.625 g/（h.m2）,力学强度为10.6 MPa。     

Physicochemical properties of binder gel in alkali-activated fly ash/slag exposed to high temperatures

The present study investigated the physicochemical properties of binder gel in alkali-activated fly ash/slag exposed to high temperatures. Strength test results showed that the strength increased until exposure to 400 °C and thereafter started to decrease. The strength increase below 400 °C was attributed to the binder gel which formed after exposure, decreasing the porosity. The dehydration of C-A-S-H and the formation of N-A-S-H simultaneously occurred, inducing the transformation of pore structure from microporous to mesoporous state. The crystallization of the binder gel resulted in an increase in the porosity, thereby inducing a decrease in the strength above 400 °C and is responsible for the transformation of the pore structure from mesoporous to macroporous state. The porosity under high temperatures had an inverse relationship with the strength, and was significantly altered as the binder gel underwent additional formation, dehydration and crystallization.     

Microstructure and properties of aluminum nitride ceramics prepared by aqueous gelcasting method with nontoxic curdlan as gelling agent

Aluminum nitride ceramics were prepared by aqueous gelcasting method and pressureless sintering technique in N₂ atmosphere using Y₂O₃ as sintering additives with nontoxic curdlan as gel system. The solidification mechanism of curdlan was studied. The effects of curdlan content and solid content on the microstructure, relative density and flexural strength of green bodies were investigated. The influences of Y₂O₃ content and sintering soaking time on the microstructure and properties of sintered bodies were also studied. The results show that, as the temperature increases to 80 °C, the ceramic powders solidify through three-dimensional gel networks of curdlan during gelling process. The green bodies can be successfully fabricated through aqueous gelcasting method with modified powder as original materials. Suitable curdlan content and solid content contribute to fabricating green body with uniform microstructures and high flexural strength. The relative density and flexural strength of sintered bodies enhance as the Y₂O₃ content and soaking time increase. The flexural strength and thermal conductivity are about 107.5∼172.3 MPa and 75.2∼112.5 W/(m·K), respectively. The sintered body with 4 wt% Y₂O₃ soaking for 3 h exhibits the highest thermal conductivity because of appropriate relative density, uniform microstructure and reasonable intergranular phase distribution. The mechanical property and thermal conductivity of sintered bodies can be improved by optimizing the gelcasting process parameter, Y₂O₃ content, and soaking time. The nontoxic gelling system will have wide application for aqueous gelcasting ceramic with complex shape.     

可德胶膜的制备及其性能分析

可德胶是一种新型的微生物多糖。由于可德胶独特的凝胶特性和生理功能,使其有较好的应用前景。本文主要研究不同温度和增塑剂对可德胶膜强度和韧性的影响。改变温度和增塑剂种类及用量制备一系列可德胶膜。对可德胶膜进行差示扫描量热分析（DSC）,研究DSC升温速率对可德胶膜热转变的影响。     

Thermo-sensitive swelling behavior in crosslinked N-isopropylacrylamide networks: Cationic,anionic, and ampholytic hydrogels

Crosslinked polymer networks of N-isopropylacrylamide (NiPAAm) containing small amounts of either anionic or cationic comonomers, or mixtures of both were fabricated and characterized in terms of their aqueous swelling and critical behavior. These gels demonstrate critical transition temperatures in aqueous media between a highly solvated, swollen gel state and a collapsed, dehydrated network over temperature ranges comparable to that of pure NiPAAm, with modifications of gel critical points and respective temperature ranges dependent upon comonomer type and content. Copolymer gel swelling ratios are significantly larger than those reported for pure homopolymer NiPAAm gels, even when only 0.5 mol % of comonomer is incorporated. At temperatures exceeding the collapse transition point, all copolymer gels collapse to a state of nearly complete dehydration, demonstrating short-time collapsed-state swelling ratios far lower than those of pure NiPAAm networks. Collapse kinetics for the ionomeric gels are much more rapid than those of pure NiPAAm, achieving collapse state equilibrium on time scales of seconds. Swelling behavior as a function of pH, buffer type, ionic strength, crosslinking, and temperature is detailed over a range of copolymer compositions. © 1993 John Wiley & Sons, Inc.     

蒸汽渗透法脱除丙烯中微量水分的研究

采用涂敷法制备了CS/PS,PVA/PS,PVA-CS/PS中空纤维复合膜并用于气相丙烯中微量水分的脱除.研究了PS基膜、原料气湿含量、流速及吹扫气流速等因素对蒸汽渗透分离性能的影响.结果表明,这些复合膜均具有良好的分离性能,其中CS-PVA/PS中空纤维复合膜具有最优的蒸汽渗透性能.     

Effects of different catalysts on the structure and properties of polyurethane/water glass grouting materials

Polyurethane/water glass (PU/WG) grouting materials were prepared in presence of different proportions of catalyst. The effects of catalyst on the mechanical properties, thermal properties, and chemical cross‐sectional morphologies of the grouting materials were also investigated. Catalyst addition can significantly increase the chemical reaction rate, reduce the gel time and curing time, and improve the thermal stability of PU/WG grouting materials. It was found that the grouting material containing 0.1 wt % BDMA + 0.1 wt % DBTDL demonstrated high fluidity, short curing time, and high early‐stage and late‐stage (up to 66.1 MPa) compression strengths. However, when the content of the added catalyst was equal to 0.5 wt %, fine cracks were formed in the material structure accompanied by the detachment of spherical particles from the PU matrix, which significantly deteriorated its mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46460.     

Particle‐size‐dependent properties of sulfonated polystyrene nanoparticles

The influence of sulfonation reaction time, temperature and the parent polystyrene (PS) particle size on the degree of sulfonation (DS), ion exchange capacity (IEC), morphology and glass transition temperature (T_g) of sulfonated polystyrene (SPS) particles was investigated. A longer reaction time (ca 2 h) at 40 °C and a smaller particle size resulted in SPS particles with a high DS. It was found that a larger PS particle size did not readily yield SPS particles with a high DS even with a longer reaction time. Contrary to the popular belief in the literature that a higher DS ensures a high IEC, we observed that the proportionality of IEC to DS is primarily controlled by the SPS particle size. Larger IEC values were obtained for larger particles rather than smaller ones despite their similar DS, owing to the presence of strong interactions between ? SO₃H groups within the particles in the latter case which restricts the availability of free H⁺ for ion exchange. The SPS particles displayed a core‐shell morphology in which the outer shell appeared because of sulfonation on the PS. The DS value and the SPS particle size significantly influenced the shell thickness and thereby the morphology of the SPS particles. Copyright © 2012 Society of Chemical Industry     

Morphology and mechanical properties of styrene-butadiene-styrene/polystyrene semi-interpenetrating polymer networks and their blends

SBS/PS semi-interpenetrating polymer networks (semi-IPNS) were synthesized by swelling a linear styrene-butadiene-styrene (SBS) triblock copolymer (SBS, Kraton 1102) with styrene monomer plus benzoin as photoinitiator and divinylbenzene as cross-linking agent. Polyblends were prepared by solution casting of SBS and polystyrene (PS) in their ideal solvents. Measurements were made for viscoelastic properties and mechanical properties of phase-separated polymer alloy (including SBS copolymers Kraton 4122), semi-IPNs and polyblends of several SBS and PS, with the same total PS content (48% PS). The dynamic mechanical behaviour shows distinct transitions for each polymer, in agreement with electron microscopy results that SBS/PS polymer alloy forms two phases; however, the phase domains were finer in the semi-IPNs than in SBS triblock copolymer and in polyblends of the corresponding polymers. Stress-strain data show that semi-IPNs exhibit higher tensile strength and modulus than the other two corresponding polymer alloys. A master curve was plotted to illustrate the stress relaxation behaviour of samples at higher temperatures. Our results also reveal that semi-IPNs have much better high-temperature mechanical strength.     

Synthesis and physical properties of Curdlan branched Ester derivatives

Curdlan is a high-molecular-weight linear β-1,3-glucan synthesized by microorganisms. A series of curdlan branched esters with a degree of substitution of three were synthesized and their physical properties and structures were compared with those of curdlan linear esters. Thermal degradation temperatures of all the curdlan branched esters were ca. 360 °C; almost the same as those of curdlan linear esters. The curdlan branched esters had melting temperatures (T _m ) higher than those of the corresponding curdlan linear ester with the same side-chain carbon number. In particular, comparing T _m of curdlan propionate, curdlan isobutyrate, and curdlan pivalate, the latter two had high T _m of over 335 °C, suggesting that the degree of branching of the side chain affects the stability of molecular chains with helix structure in their crystals. Highly transparent films were prepared from the curdlan branched esters. These films exhibited higher Young’s modulus and tensile strength compared with those of films composed of the linear equivalents with the same side-chain carbon numbers. These results indicate that curdlan branched esters are promising thermoplastics with favorable thermal and mechanical properties because of the closer packing structure of their molecular chains than that of the corresponding curdlan linear esters.