阳离子纤维素醚的合成及流变性能研究

在自制碱催化剂存在下,工业羟乙基纤维素与N-(2,3-环氧丙基)三甲基氯化铵(GTA)阳离子化试剂反应,干法制备高取代度季铵盐型阳离子纤维素醚(CHEC)。用均匀实验方案考察了GTA与羟乙基纤维素(HEC)用量比、NaOH与HEC用量比、反应温度、反应时间对反应效率的影响,并通过蒙特卡洛蒙特卡罗模拟得到优化工艺条件,并通过实验验证得到阳离子醚化试剂的反应效率达到95%。同时探讨了其的流变性能。结果表明,CHEC的溶液呈现非牛顿流体特征,随着溶液质量浓度增大其表观粘度增大;在一定浓度的盐溶液中,CHEC表观粘度随着外加盐浓度的增大而减小。同一剪切速率下,CaCl2溶液体系中CHEC的表观粘度比NaCl溶液体系中CHEC的表观粘度大。     

阳离子化羟乙基纤维素醚的合成与溶液性质

以工业羟乙基纤维素(HEC)和N-(2,3-环氧丙基)三甲基氯化铵(GTA)为原料,在碱催化剂下干法制备不同取代度季铵盐型阳离子羟乙基纤维素醚。用均匀设计法优化合成条件,并通过蒙特卡罗模拟得到优化工艺条件,通过实验验证得到阳离子醚化试剂的反应效率达到85%以上,取代度达到0.49。同时探讨了阳离子羟乙基纤维素醚(QHEC)在不同介质中的黏性行为。结果表明,阳离子羟乙基纤维素醚在纯水中具有典型的聚电解质黏性行为,随着QHEC浓度减小,比浓黏度增大。同一QHEC质量浓度下,NaCl溶液中QHEC的比浓黏度总大于KCl溶液中QHEC的比浓黏度;随着外加盐NaCl溶液浓度的增大,其比浓黏度减小。     

新型阳离子羟乙基纤维素醚的合成

以羟乙基纤维素为原料、2-氯-4,6-二（N,N-二甲基-N-苄基-1,3-丙二胺）-1,3,5-均三嗪（BT）为改性剂,合成新型季铵盐阳离子羟乙基纤维素醚,讨论了影响产物取代度的主要因素。结果表明：在异丙醇稀释剂中,NaOH和改性剂的物料量比为1．2：1,改性剂和羟乙基纤维素的物料量比为1．5：1,反应温度为95℃、反应时间为5h时,产物的取代度最高达0．24。     

表面活性剂对十六烷基羟乙基纤维素溶液黏度的影响

通过流变仪研究了几种表面活性剂对十六烷基羟乙基纤维素(CHEC)溶液黏度的影响.结果表明,CHEC溶液的黏度随表面活性剂质量分数的增加先升高,达到最大值后逐渐下降;温度对表面活性剂和CHEC混合溶液黏度的影响与表面活性剂和CHEC形成的复合物有关;表面活性剂与CHEC的疏水缔合作用强弱顺序是AES>6501>CAB.     

热缔合型阳离子纤维素的制备及性能

以羟乙基纤维素(HEC)、正丁基缩水甘油醚(BGE)和2,3-环氧丙基三甲基氯化铵(GTA)为原料,通过改变纤维素衍生物亲水基和疏水基的比例调控亲水-亲油平衡的方法制备了热缔合型阳离子纤维素(TACC)。首先,HEC与BGE反应制备了疏水化纤维素(HBPEC);然后,HBPEC与不同质量的GTA反应制备了4种不同GTA取代度的热缔合型阳离子纤维素(TACC)。采用FTIR、~1HNMR、元素分析对TACC进行了表征,证实TACC上已成功接枝了BGE和GTA。考察了GTA取代度、TACC质量浓度、NaCl浓度及剪切速率对TACC温敏增稠性能的影响。结果表明:40℃下,当GTA的取代度从0.12增加到0.32时,15 g/L的TACC水溶液的最大黏度(η_(max))从13 mPa·s增大到54 mPa·s,最大与最小黏度比(η_(max)/η_(min))从1.5增加到7.0,与最大黏度对应的温度(T_(max))从25℃升高到40℃;TACC浓度的增大使水溶液黏度及温敏增稠性能提高;相反地,NaCl浓度的增加会使TACC水溶液的黏度和温敏增稠性能降低,且会使T_(max)减小。     

无稳定剂体系下的双水相聚合相分离

以丙烯酰胺（AM）、季铵类阳离子甲基丙酰氧乙基三甲基氯化铵（DMC）和丙烯酰氧乙基二甲基苄基氯化铵（AODBAC）为单体，以2，2'-偶氮双[2-（5-甲基-2-咪唑啉-2-基）丙烷]二盐酸化物（VA044）为引发剂，在水溶液中进行无稳定剂体系下的双水相共聚。利用紫外分光光度仪在线观察体系的分相过程并测定体系的临界分相点。通过改进的溴化法测定临界转化率（X_c）。利用黏度法测定临界分子量（M_c）。并对各个因素对于X_c和M_c的影响进行研究。结果表明具有表面活性的阳离子单体AODBAC对体系的相分离具有较好的促进作用。引发剂的用量和AODBAC的摩尔分数（f_AODBAC）对于X_c的影响较小，反应温度升高会使X_c增大。总单体浓度和f_AM的升高会使X_c减小。引发剂用量的增加、反应温度和f_AODBAC的升高都会使M_c减小。f_AM和单体浓度的增加会使M_c显著增加。     

改性羟乙基纤维素水溶液流变性能的研究进展

综述了经疏水化改性和阳离子化改性的羟乙基纤维素水溶液的流变学性能及其影响因素,如改性羟乙基纤维素的相对分子质量、溶液浓度、温度、侧链的种类、侧链链长、物质的量分数及其分布等;评述了表面活性剂与改性羟乙基纤维素形成复合体系溶液的流变性能。分析了由于改性羟乙基纤维素分子结构的改变而使其溶液体系增黏的机理。     

碱溶性羟乙基纤维素在复合溶剂体系中的流变性能

使用平行板流变仪,以氢氧化钠/硫脲/尿素/水溶液作为碱溶性羟乙基纤维素(HEC)的复合溶剂,研究了HEC在该溶剂体系中的流变性能,并考察了剪切速率、温度及溶液浓度对溶液的非牛顿指数、结构黏度指数及黏流活化能的影响。结果表明:溶液属于切力变稀型假塑性流体,随溶液温度下降及浓度增加,溶液的表观黏度和结构黏度指数增大,非牛顿性增强;该溶液的黏流活化能随着剪切速率的增加而下降。     

[Bmim]Cl中CrCl3-AlCl3催化纤维素降解制取5-羟甲基糠醛

5-羟甲基糠醛是一种具有很高利用价值的化学平台化合物。以离子液体1-丁基-3-甲基咪唑氯盐（[Bmim]Cl）为溶剂,以CrCl₃和AlCl₃为复合催化剂,在油浴加热条件下催化纤维素降解制取5-羟甲基糠醛,研究了催化剂种类、催化剂量、温度、纤维素浓度、气氛、纤维素聚合度、反应规模等不同因素对纤维素降解制取5-羟甲基糠醛的影响。结果表明,[Bmim]Cl用量为10 g,棉花添加量为0.5 g,x（CrCl₃）=25%（mol）,x（AlCl₃）=2.5%（mol）,反应温度为120℃,反应气氛为N₂（dry）气氛,反应时间为4 h时,HMF产率最高,达到59%。此外,反应过程中水的作用机理也被给予了相应解释。     

低黏二氰胺类离子液体乙烯汽液相平衡研究

从工业废气中回收分离乙烯（C₂H₄）具有重要意义,选用了三种低黏度二氰胺类离子液体,分别测定了293.15~333.15 K下其密度、黏度等物化性质,研究了其对乙烯（C₂H₄）吸收性能。采用非随机（局部）双液体模型（NRTL）关联了三种二元体系溶解度数据,实验值与计算值的平均相对偏差均小于3%。结果表明,低黏度二氰胺类离子液体对C₂H₄气体吸收性能良好,其中阳离子侧链长度增加和羟基功能团引入可增强对C₂H₄溶解度。同时,离子液体1-丁基-3-甲基咪唑二氰胺盐（[Bmim][DCN]）经过3次的吸收解吸循环,仍可以保持较好的C₂H₄吸收性能,表明该离子液体循环稳定性好,而1-丁基-3-甲基咪唑二氰胺盐（[Bmim][DCN]）对乙烯吸收量较高,具有作为C₂H₄吸收剂的潜力。     

疏水缔合羟乙基纤维素的合成及性能表征

为改进羟乙基纤维素的溶液性能,通过羟乙基纤维素与长链溴代烷烃的大分子反应,制得疏水缔合羟乙基纤维素(BD-HAHEC);经由正交实验确定最优化工艺参数为:醚化剂∶羟乙基纤维素(质量比)=3∶10,活化剂浓度为4%,在80℃条件下反应5 h。用傅立叶红外光谱仪、粘度计和剪切流变仪对产品进行结构表征和性能测定,结果表明,与普通羟乙基纤维素相比,疏水改性羟乙基纤维素水溶液在增稠性、耐温耐盐性、抗剪切性等性能上均有明显提高;在相同反应条件下,由溴代十四烷改性的羟乙基纤维素具有比溴代十二烷改性更强的增稠性能。     

Study of rheological behavior of hydrophobically modified hydroxyethyl cellulose

Hydrophobically modified hydroxyethyl cellulose (BD‐HAHEC) was synthesized by the macromolecular reaction of hydroxyethyl cellulose (HEC) with bromododecane (BD). Study of the effects of polymer concentration, shear rate, temperature, and electrolytes on the rheological behavior of BD‐HAHEC indicated that the polymers had high viscosity, excellent viscosity retention in brine water, good thermal stability, and surface activity. Furthermore, investigation of the micromorphology of BD‐HAHEC solutions revealed the close relationship of rheological behavior and a hydrophobically associating effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3346–3352, 2006     

Structure and Property of Cationic Hydroxyethyl Cellulose

Through the macromolecule reaction, hydroxyethyl cellulose (HEC) was modified by quaternary ammonium monomer (GTAC) and the cationic HEC(C-HEC) with optimized viscosity was synthesized successfully. The structure of C-HEC was characterized by FTIR and Kjeldahl nitrogen content measurement. The introduction of cationic group onto the molecules of HEC resulted in the increase of the hydrophilicity of HEC. The dependence of the aqueous solution properties of C-HEC on the polymer concentration, GTAC dosage, additional electrolyte, temperature and shear rate were studied comprehensively.     

Effect of Compound Surface Treatment on the Performance of Poly(butylene succinate)/Chemithermomechanical Pulp Fiber Composites

Chemithermomechanical pulp fiber was pretreated by alkali solution to alter the surface characteristics of fibers. The untreated and treated fibers were used to prepare poly(butylene succinate)/chemithermomechanical pulp fiber composites with or without the incorporation of cellulose fatty acid ester (hydroxyethyl cellulose lauric acid ester). X-ray photoelectron spectrum analysis shows that the O/C ratio on the fiber surface increased after alkali treatment, indicating that part of lignin was removed during alkali treatment process. Scanning electron microcopy images indicate that the fiber surface was changed to rough after alkali treatment. The modification effect of hydroxyethyl cellulose lauric acid ester reflects as the improvement of fiber order in matrix, together with the enhancement of interfacial bonding, whereas, the modification effect of alkali treatment is mainly due to the enhancement of interfacial bonding. The integrated mechanical properties of composite prepared by alkali-treated fibers are superior to those of composite prepared by hydroxyethyl cellulose lauric acid ester-treated fibers. The combination of these two modification methods favors the enhancement of tensile and impact strengths of composite. However, in comparison with the composite prepared only by alkali treatment, the flexural strength and modulus would be despaired in a certain degree. When fibers were alkali treated, the shear viscosity of composite exhibited a larger increase, whereas the shear viscosity of composite prepared fibers with hydroxyethyl cellulose lauric acid ester treatment exhibits a slight decrease.     

Investigation of local viscosity in polymer solutions by means of electrolytic conductivity

The local viscosity in aqueous solutions of polymers (dextran and hydroxyethl cellulose) and low-molecular weight viscogenic compounds (glycerol and d-glucose) has been studied by measuring the electrolytic conductivity of probe electrolytes. For low-molecular weight viscogenic compounds the local viscosities determined were close to the macroscopic viscosities of the solutions, whereas pronounced differences exist for polymer solutions. Of particular interest was the finding that the local viscosity for dextran was only marginally higher than the local viscosity for the corresponding monomer, d-glucose. The local viscosity for hydroxyethyl cellulose was somewhat higher than the local viscosity for dextran, indicating greater flexibility of the dextran chain.     

Dilute solution properties of hydroxyethyl starch

The dilute solution properties of hydroxyethyl starch (HES) were examined by using the techniques of osmometry, light scattering, and viscometry. The molecular weight range was approximately 2 × 10⁶–0.06 × 10⁶. Since HES is a branched molecule, its properties were compared with those of two linear counterparts, ethyl hydroxyethyl cellulose and hydroxyethyl cellulose. The branching index g was estimated to be about 0.3 when calculated from the intrinsic viscosity, radii of gyration, and second virial coefficients.