羧甲基多糖对羟丙基甲基纤维素溶液性能的影响

利用羧甲基淀粉、羧甲基纤维素与羟丙基甲基纤维素进行复配,研究羧甲基类多糖与羟丙基甲基纤维素的协同作用,并对其增稠作用的机理进行研究。结果表明:羧甲基淀粉钠和羧甲基纤维素钠对非离子型纤维素混合醚都有一定的增黏协同效应,且淀粉羧甲基物比纤维素羧甲基物的增黏效应更明显。     

改性羧甲基羟丙基纤维素在苯丙乳液中的增稠性研究

用旋转度计研究了改性羧甲基羟丙基纤维素（Ｍ－ＣＭＨＰＣ）在苯丙乳液（ＳＣ）中的增稠性。在较低在Ｍ－ＣＭＨＰＣ用量范围内,增稠体系呈现罗明显的Ｂｉｎｇｈａｍ塑性流型特征。透射电子显微镜观察进一步证实了增稠体系形成以ＳＣ粒子为联结点,Ｍ－ＣＭＨＰＣ分子为桥的“桥式”网络凝胶结构。形成较完整的网络凝中归因于Ｍ－ＣＭＨＰＣ的复醚结构。结构形成使增稠体系呈现较出服值Ｙ和触变度Ｔｘ,Ｍ－ＣＭＨＰＣ较高的增稠效     

羟丙基甲基纤维素（HPMC）发展状况和开发前景

一、概况 羟丙基甲基纤维素(HPMC)是纤维素醚工业中产量最低、物化性能最好、用途最广泛的纤维素醚类,属于非离子型高分子化合物。与离子型甲基羧甲基纤维素不同,它与重金属不起反应。根据其成品中甲氧基含量和羟丙基含量的比例不同,可得到在性能上有所差别的各个品种。 HPMC实际上是一种经环氧丙烷改性的甲基纤维素,故它具有与甲基纤维素相类似的冷水溶解和热水不溶的特性。HPMC在有机溶剂中的溶解性优于其水溶性,它能溶于甲醇和乙醇溶     

羟丙基纤维素的合成——第一报 气—固相合成药片用赋形剂低取代羟丙基纤维素的研究

羟丙基纤维素是一种多用途的非离子型纤维素醚。它广泛地应用于食品、医药、粘结、增稠、聚合分散、日用化工等工业。在医药应用方面,它已经开始成功地被用作药物的载体、药片薄膜包衣和微胶囊包衣材料。起着改造药物剂型、改善给     

羟丙基甲基纤维素前景看好

羟丙基甲基纤维素（简称HPMC）是纤维素醚工业中产量最低、物化性能最好、用途最广泛的纤维素酸类,属于非离子型纤维素醚类。HPMC实际上是一种经环氧丙烷改性的甲基纤维素。因为,它具有与甲基纤维素（MC）相类似的特性,通常也将HPM称为MC的衍生物。由于HPM具有优良的增稠、乳化、成膜、保护胶体、保持水分、粘合、抗酶以及代谢惰性等性能,俗称“工业味精”,可广泛应用于涂料、聚合反应、建筑材料、油田、纺织、食品、医药、日用陶瓷、电子器件以及农业种子等领域。我国的非离子型纤维素醚（包括HPM）近几年发展比较迅速。据调…     

改性羟甲基羟丙基纤维素在苯丙乳液中的增稠性研究

用旋转粘度计研究了改性波甲基羟丙基纤维素（M-CMHPC）在苯丙乳液（SC）中的增稠世。在较低的M－CMHPC用量范围内,增稠体系呈现较明显的Bingham塑性流型特征。透射电子显微镜观察进一步证实了增稠体系形成以SC粒子为联结点,M－CMHPC分子为桥的“桥式”网络凝胶结构。形成较完整的网络凝胶可归因于M-CMHPC的复醚结构。结构形成使增稠体系呈现较高的屈服值Y和融变度Tx。M-CMHPC较高的增稠效能使增稠体系呈现较高的塑性粘度值PV。较高的Y、Pv和Tx值有助于提高增稠体系的胶体稳定性。     

羟丙甲基纤维素的合成工艺的改进研究

基于现有羟丙基甲基纤维素合成方法的研究,采用氮气保护碱化和分步醚化方法,制得具有较高黏度的羟丙基甲基纤维素。该方法合成的羟丙基甲基纤维素(HPMC)具有在冷水中分散性能好、黏度高、增稠保水性能好的优点,适合建筑用的胶水的生产,可用于砌墙、抹灰、粉刷、嵌缝等施工中,同时也适合用于干混凝砂浆。     

取代基及分子量对非离子型纤维素醚表面特性的影响

根据Washburn的浸渍理论(Penetration Theory)和van Oss-Good- Chaudhury的组合理论(Combining Theory)及应用柱状灯芯技术(Column Wicking Technique),对几种非离子型纤维素醚,如甲基纤维素、羟丙基纤维素和羟丙基甲基纤维素的表面特性进行了测试。由于这些纤维素醚的取代基、取代度和分子量不同,所以它们的表面能及其组成部分有着明显的差异。数据说明,非离子型纤维素醚Lewis碱大于Lewis酸,表面自由能的主要成分是Lifshitz-van der Waals力。羟丙基的表面能及其成分都大于羟甲基。而在相同取代基和取代度的前提下,羟丙基纤维素的表面自由能正比于分子量;而羟丙基甲基纤维素的表面自由能则正比于取代度,反比于分子量。实验还发现非离子型纤维素醚中的取代基羟丙基和羟丙基甲基的表面能似乎都大于纤维素的表面能,而实验证明所测试得出的纤维素的表面能及其成分的数据是与文献所吻合的。     

STRUCTURE~ CEL 乙基羟乙基纤维素在皂基沐浴露中的应用

StructureR詳CEL 4400E是一种新型的、使用方便的水溶性非离子流变调节剂,具有优异的增稠效果、外观改善性能和泡沫改进特性。实验表明,在皂基沐浴露体系中,Structure CEL 4400E在增稠,提高配方稳定性,增泡和稳泡性能上,都优于羟乙基纤维素和羟丙基甲基纤维素。     

水溶性纤维素醚的制备及应用

本文介绍了羧甲基纤维素，甲基纤维素、羟乙基纤维素和羟丙基纤维素的制备与用途。     

乳胶漆中羟乙基纤维素添加方法的研究

通过研究发现羟乙基纤维素(HEC)在乳胶漆生产中添加方式不同(即在分散研磨阶段添加还是在调漆阶段添加),对乳胶漆最终黏度、贮存稳定性等方面都有比较明显的影响。结合纤维素增稠机理分析认为这些方面的影响主要是由于纤维素在乳胶漆中的分散状态引起的,而乳胶漆中纤维素的分散状态取决于它的添加方式。     

Poly(vinyl alcohol)–lignin blended resin for cellulose‐based composites

Wood has limitations in strength because of its biostructural defects, including vessels. To overcome this limitation, composite materials can be innovated by breaking wood down into cellulose and lignin and reassembling them for bio‐originating strong structural materials. In this study, an ecofriendly resin was developed that was suitable for cellulose‐based composites. To overcome the low dimensional stability of lignin and to increase its interactions with cellulose, it was blended with poly(vinyl alcohol) (PVA). The PVA–lignin resin was characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, thermal analysis, mechanical tensile testing, and lap‐shear joint testing. The adhesion properties of the PVA–lignin resin increased with increasing PVA content. PVA played the role of synthetic polymer and that of linker between the cellulose and lignin, like hemicellulose does in wood. The PVA–lignin resin exhibited a high miscibility, mechanical toughness, and good adhesion properties for nanocellulose composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46655.     

Amphiphilic graft copolymer latex membranes. VI. Poly(vinyl alcohol)–acrylonitrile–N-hydroxyethyl acrylamide graft copolymer latex membranes

Poly(vinyl alcohol)(PVA)–acrylonitrile(AN)–N-hydroxyethyl acrylamide (HEAAm) graft copolymer latex membranes were prepared and properties of the membranes were compared with those of PVA–AN graft latex membranes and Cuprophane PT-150. The physical constants of HEAAm were determined and the tautomerization between hydroxyethyl amide group and aminoethyl ester group upon pH changes was ascertained by infrared spectrum of poly(HEAAm) film. An increase in HEAAm content in the membrane enhanced permeabilities of solute in aqueous solutions in comparison with PVA–AN graft latex membranes, maintaining good mechanical properties in wet state. With pH variation, the permeability of the nonionic solute was unchanged, but that of the anionic solute in acidic condition was superior to that in basic condition, and the permeability of the cationic solute exhibited the opposite trend. The behavior of ionic solute were attributable to the effect of the tautomerization of the functional group in the membrane.     

Grafting of poly(vinyl alcohol) on natural rubber latex particles

Poly(vinyl alcohol) (PVA) was grafted on natural rubber (NR) latex particles (NR‐g‐PVA) using potassium persulfate to generate active radicals on both NR particle surface as well as PVA molecules. ¹H‐ and ¹³C‐nuclear magnetic resonance spectroscopy suggested a possibly chemical attachment of PVA on the NR. The amount of graft‐PVA expressed in term of grafting percentage (%G) increased almost linearly with the amount of PVA adding to the NR latex. Measuring by dynamic light scattering, the particle size of NR‐g‐PVA particles was larger than the size of unmodified NR, also it increased with the molecular weight and %G of PVA. Transmission electron microscopy images of the NR‐g‐PVA latex particles revealed that the size of PVA‐grafted NR particle was enlarged by a layer of graft‐PVA surrounding the NR particle. Given by the graft‐PVA layer surrounding NR particles, the NR‐g‐PVA latex particles possessed better colloidal stability as lowering pH compared with the unmodified NR latex. Comparing with unmodified NR particles, the electrophoretic mobility of NR‐g‐PVA particles was lower due to the presence of graft‐PVA that shifted the shear plane further away from the surface of the particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Solid state NMR and LVSEM studies on the hardening of latex modified tile mortar systems

Construction mortars contain a broad variety of both inorganic and organic additives beside the cement powder. Here we present a study of tile mortar systems based on portland cement, quartz, methyl cellulose and different latex additives. As known, the methyl cellulose stabilizes the freshly prepared cement paste, the latex additive enhances final hydrophobicity, flexibility and adhesion. Measurements were performed by solid state nuclear magnetic resonance (NMR) and low voltage scanning electron microscopy (LVSEM) to probe the influence of the latex additives on the hydration, hardening and the final tile mortar properties. While solid state NMR enables monitoring of the bulk composition, scanning electron microscopy affords visualization of particles and textures with respect to their shape and the distribution of the different phases.

Within the alkaline cement paste, the poly(vinyl acetate) (VAc)-based latex dispersions stabilized by poly(vinyl alcohol) (PVA) were found to be relatively stable against hydrolysis. The influence of the combined organic additives methyl cellulose, poly(vinyl alcohol) and latexes stabilized by poly(vinyl alcohol) on the final silicate structure of the cement hydration products is small. But even small amounts of additives result in an increased ratio of ettringite to monosulfate within the final hydrated tile mortar as monitored by ²⁷Al NMR. The latex was found to be adsorbed to the inorganic surfaces, acting as glue to the inorganic components. For similar latex water interfaces built up by poly(vinyl alcohol), a variation in the latex polymer composition results in modified organic textures. In addition to the networks of the inorganic cement and of the latex, there is a weak network build up by thin polymer fibers, most probably originating from poly(vinyl alcohol). Besides the weak network, polymer fibers form well-ordered textures covering inorganic crystals such as portlandite.     

油井水泥专用丁苯胶乳的实验评价

针对传统丁苯胶乳在油井水泥浆中适用性能差的问题,采用种子乳液聚合方法合成了一种油井水泥专用丁苯胶乳,并对其进行了微观结构和应用性能评价。该丁苯胶乳物理性能、红外及热失重分析结果表明：该丁苯胶乳乳液稳定性好,高温下分子结构稳定。丁苯胶乳水泥浆的应用性能结果和微观结构分析表明：该丁苯胶乳水泥浆API失水可控制在50 mL内,耐盐性能好,可解决传统胶乳水泥浆稠化实验"鼓包"、"包心"等问题;加有该丁苯胶乳的水泥浆早期强度发展快,胶凝强度过渡时间短;丁苯胶乳能细化水泥浆的孔径结构,提高水泥浆的胶结强度和形变能力,并且其水泥石的柔韧性比原浆水泥石提高了30%;此外,能够满足深井、超深井和气井等复杂井的固井作业要求。     

聚乙烯吡咯烷酮对聚醋酸乙烯酯共聚乳液性能的影响

以醋酸乙烯酯(VAc)和丙烯酸丁酯(BA)为聚合单体、聚乙烯醇(PVA)为保护胶体、聚乙烯吡咯烷酮(PVP)为分散剂、十二烷基硫酸钠(SDS)为表面活性剂及羟丙基甲基纤维素(HMPC)为增稠剂等,制备出一种低黏度聚醋酸乙烯酯(PVAc)乳液胶粘剂。考察了PVP用量对PVAc乳液胶粘剂的黏度、粘接性能、稳定性能及单体转化率等影响。结果表明:红外光谱(FT-IR)证实,PVP参与了VAc和BA的接枝共聚反应;适量的PVP可使乳液黏度明显降低;当w(PVP)=0.15%时,PVAc乳液胶粘剂的综合性能相对最好。     

Influence of polymers on microstructure and adhesive strength of cementitious tile adhesive mortars

The impact of polymer modification on the physical properties of cementitious mortars is investigated using a multimethod approach. Special emphasis is put on the identification and quantification of different polymer components within the cementitious matrix. With respect to thin-bed applications, particularly tile adhesives, the spatial distributions of latex, cellulose ether (CE), polyvinyl alcohol (PVA), and cement hydration products can be quantified. It is shown that capillary forces and evaporation induce water fluxes in the interconnected part of the pore system, which transport CE, PVA, and cement ions to the mortar interfaces. In contrast, the distribution of latex remains homogeneous. In combination with results from qualitative experiments, the quantitative findings allow reconstruction of the evolution from fresh to hardened mortar, including polymer film formation, cement hydration, and water migration. The resulting microstructure and the failure modes can be correlated with the final adhesive strength of the tile adhesive. The results demonstrate that skinning prior to tile inlaying can strongly reduce wetting properties of the fresh mortar and lower final adhesive strength.     

The role of polyvinyl alcohol in emulsion polymerization

Emulsion polymerization of styrene (St) and vinyl acetate (VAc) in the presence of conventional polyvinyl alcohol (PVA), PVA modified with a terminal alkyl group or PVA modified with a terminal thiol group (HS-PVA) was compared. Whereas stable PVAc latexes were obtained, a stable PSt latex was obtained only in the case of HS-PVA. From the adsorption isotherms of these PVAs on the surface of PVAc and PSt latex particles, as well as the grafting efficiencies of VAc and St onto HS-PVA in relation to the stability of the polymerization process, the role of PVA in the emulsion polymerization was discussed.     

Permeation characteristics of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membranes

Poly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n-hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm². The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n-haxane or a poor solvent for PVAc.