Gelling behavior of MgAl2O4 slurries with a common dispersant

MgAl₂O₄ transparent ceramics were shaped by a commonly used polyacrylic acid (PAA), which acted as both dispersant and gelling agent. The spinel slurries were prepared by ball-milling MgAl₂O₄ powder, PAA, and water in an attrition mill. The gelling of slurries happened at room temperature in air atmosphere without any other organic additive. The gelling mechanism was the formation of chelates between Mg²⁺ and carboxyl groups (-COO⁻) of PAA. The frequency-based testing method was applied to investigate the gelling process of the as-prepared slurry. In addition, a novel in situ characterization method based on a modified indentation testing was invented to better understand the strengthening of the wet green body with time and to guide when demolding could be carried out. After sintering, transparent MgAl₂O₄ ceramics with high in-line transmittance were resulted.     

Influence of carboxymethylation on the gelling capacity,rheological properties,and antioxidant activity of feruloylated arabinoxylans from different sources

Feruloylated arabinoxylans (FAX) are gelling polysaccharides presenting antioxidant activity (AC) and potential application as delivery systems. The influence of carboxymethylation on the gelling capacity, rheological properties, and AC of FAX from wheat flour (FAX1) and maize distillers grains (FAX2) was analyzed. The degree of substitution of carboxymethyl groups was 0.27 and 1.77 for carboxymethylated FAX1 (CFAX1) and FAX2 (CFAX2), which presented a change in M _n from 446 to 362 kDa and from 120 to 180 kDa, and a loss in FA content from 1.05 to traces and from 10.13 to 0.12, respectively, after carboxymethylation. G′ value at the end of rheological tests for FAX1 (71 Pa) and FAX2 (726 Pa) was higher than the corresponding G″ value. In contrast, G″ value for CFAX1 (0.35 Pa) and CFAX2 (0.03 Pa) was higher than the respective G′ value, indicating that they do no form gels. The AC increased in CFAX1 in relation to FAX1 from 4.49 to 8.30 mmol Trolox equivalent antioxidant capacity (TEAC) kg⁻¹, respectively, while it decreased in CFAX2 with regard to FAX2 from 11.31 to 9.43 mmol TEAC kg⁻¹, respectively. Carboxymethylation could be a path to design FAX derivatives offering alternative potential applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48325.     

磷酸酯胶凝剂的合成及油基压裂液性能评价

探讨了油基压裂液胶凝剂磷酸酯的合成条件 ,进而对配制的压裂液性能进行了评价。实验结果表明 ,用所合成的磷酸酯胶凝剂配制的柴油基压裂液具有较快的交联速度、良好的耐温性能和耐温耐剪切性能以及快速破胶等综合性能 ,可用于强水敏性、低压低渗透地层的压裂改造。     

偶联剂KH-560对CE/纳米-SiO_2复合材料凝胶性的影响

采用高速均质剪切法制备CE/纳米-SiO2复合材料,通过测试凝胶化时间和粘度变化,考察了偶联剂KH-560表面处理纳米-SiO2对复合材料凝胶性的影响。结果表明,KH-560能够有效提高复合材料的凝胶特性;在90℃时,相对未处理的CE/纳米-SiO2复合材料,经KH-560表面处理后的CE/纳米-SiO2复合材料粘度提高率为15.99%,凝胶化时间缩短率为11.34%。     

海藻酸钠-高甲氧基果胶复合体系凝胶特性的研究--蔗糖、Ca2+、葡萄糖酸-δ-内酯对复合体系凝胶特性的影响

研究了蔗糖、Ca2+、葡萄糖酸-d-内酯对海藻酸钠—高甲氧基果胶复合体系凝胶特性的影响。结果表明:蔗糖、Ca2+对该体系的凝胶特性影响很大,适量蔗糖的添加不仅可增加体系的凝胶强度和持水性,还可增加凝胶的融点;Ca2+的添加可使体系的凝胶类型从热可逆变成热不可逆,且对体系凝胶强度的影响与其对海藻酸钠的影响类似;在海藻酸钠、高甲氧基果胶单独不能形成凝胶的条件下,葡萄糖酸-d-内酯的添加可诱导两种胶的混合物形成凝胶,且该复合物的凝胶强度与葡萄糖酸-d-内酯的浓度、胶体总浓度有关。     

制备聚合物冻胶用有机铬和有机铬铝交联剂组成研究

为了改善制备聚合物冻胶堵水调剂剂用的延缓作用有机铬交联剂的性能，合成了多种有机铬和有机铬铝交联剂，讨论了配方因素和操作条件的影响，考察了这些交联剂与HPAM（日本三菱公司的MO4000）形成冻胶的过程和冻胶强度（粘度）。成胶溶液中HAPM浓度4000mg/L,Cr^3 或Cr^3 Al^3 浓度1.5mmol/L,NaCl浓度8000mg/L,pH＝6,室温成胶。实验研究结果如下：（1）在单配体体系中，乳酸铬的延缓交联效果优于丙酸铬；（2）在双配体体系中，乳酸／丙二酸铬的延缓交联成于乳酸／丙酸铬；（3）加入乙二醇的三配体体系乳酸／丙酸／乙酸铬可使交联时间延迟48小时以上；（4）Cr^3 ,Al^3 摩尔比范围适当的乳酸／丙二酸／乙酸铬铝具有良好的延迟交联作用，可在很宽的pH范围使用；（5）亚硝酸钠作为重铬酸钾还原剂的使用效果优于硫脲和亚硫酸钠，使用应过量；（6）有机酸，Cr理论摩尔比为3：1，实际摩尔比至少为4：1，计入调节pH的廉价酸如乙酸时至少为11：1；（7）加入草酸盐离子可防止生成的HPAM／Cr^3 冻胶发生失水收缩。     

水平井化学堵水配套药剂研究

针对水平井化学堵水需要,研发了3种化学剂.一是化学环空封隔材料,由可溶性淀粉、丙烯酸、交联剂、淀粉酶、引发剂等在水溶液中聚合而成,讨论了合成条件.35%、45%的反应混合物1 PV注入填砂管,在60℃聚合48或24小时,水测突破压力梯度＞30 Mpa/m.聚合产物有弹性,在水中发生溶胀、降解和溶解,最终产物包括未溶解、部分溶解的淀粉、多糖、短链聚丙烯酸等,固体物粒径＜100μm,降解96小时后黏度4 mpa·s,降解时间随温度升高(35～85℃)而减小(从约100小时到约20小时).二是聚合物铬凝胶,聚合物为北京恒聚的耐温抗盐聚合物,无机铬交联剂中的还原剂亚硫酸盐为工业副产物,加有0.01%无机强还原剂.三是无机强造壁封堵剂,由G级油井水泥、硅灰、超细水泥、聚丙烯纤维组成,凝固时间3～8小时,抗压强度＞12 Mpa.     

过氧化脂质对分离蛋白凝胶性质的影响

以大豆为原料,通过常温下正己烷浸提去油,得到高脂肪氧合酶活力的豆粕,采用不同干热程度处理得到酶活不同的豆粕,进而以碱溶酸沉法制备分离蛋白。发现不同脂质过氧化程度的豆粕提取出的分离蛋白性质差异比较显著。不同蛋白氯仿-甲醇提取液的荧光测定证实了过氧化脂质的存在。浊度反映了蛋白中不溶性聚集体的含量。凝胶的流变、质构和渗透性测定表明了不同程度蛋白聚集的凝胶性质的变化,而凝胶的扫描电镜图也显示了凝胶微观结构随灭酶程度的变化。     

变性淀粉对烘焙果酱品质的影响

探讨了6种蜡质玉米变性淀粉对烘焙果酱保水胜、耐烘焙性、凝胶特性、外观品质和口感的影响,结果表明,两种低交联度磷酸盐交联羟丙基化蜡质玉米变性淀粉,由于其耐烘焙性较差,不宜在烘焙果酱中应用.另外两种磷酸盐交联羟丙基化蜡质玉米变性淀粉和两种己二酸交联醋酸酯化蜡质玉米变性淀粉都能显著改善烘焙果酱的耐烘焙性和持水性,赋予产品良好的组织状态和口感,其中,高交联度磷酸盐交联羟丙基化蜡质玉米变性淀粉CR3010还具有良好的热稳定性和耐酸性能,尤其适合应用于烘焙果酱中.     

Synthesis of pure zeolite Y using soluble silicate, a two-level factorial experimental design

Four methods were used for the synthesis of pure zeolite Y using soluble silicate as a silica source: (1) the gelling of soluble silicate to silica–alumina gel, by aluminate (or aluminium sulphate), (2) the precipitation of soluble silicate to precipitated silica–alumina gel, by aluminate (or aluminium sulphate), (3) the gelling of soluble silicate by sulphuric acid plus alumina impregnation, and (4) the precipitation of soluble silicate by sulphuric acid plus alumina impregnation. A 2⁴ two-level factorial design was used to study the influence of four different variables on the purity of zeolite Y (expressed in terms of degree of crystallinity). The ageing time turned out to be the most significant variable. Synthesis time, alkalinity and mixing rate were also found to be statistically significant. X-ray diffraction patterns were used to characterize the samples, which ranged from well-crystallized faujasite structures to amorphous materials. The highest purity achieved in method (1) was 38%. The best synthesis condition derived from method (1) was applied to the other three methods. Only method (4) yielded the pure zeolite Y. Therefore, the effect of silica–alumina precursor preparation on producing the pure zeolite Y is extremely important.