聚酯改性剂SIPM水分分析方法的探讨

探讨了SIPM水分分析方法—重量法与卡尔·费休试剂法,并以试验证明卡尔·费休法具有较高的准确度。精密度及可行性,并能减少分析能耗,大大提高了分析工作效率,缩短了原料进厂的等待时间。卡尔·费休试剂法可以代替重量法。     

关于乙醛中水分测定方法的探讨

通常,要想准确测定化工产品中水分含量是比较困难的,因无论是取样、做样都要受空气温度、湿度等因素的影响,尤其是对于低沸点的乙醛(沸点20.8℃)来说,更比较困难。一般来说,测定化合物中水分含量的方法有以下几种:①卡尔·费休法;②色谱法;③重量法。因乙醛沸点太低,不能应用重量法,为此进行了卡尔·费休法和色谱法的试验,以确定乙醛中水分的测定方法。 1 卡尔·费休法测定乙醛中水分的试验用卡尔·费休法测定有机、无机化工产品中的水分是国内外公认的比较准确的方法。但     

卡尔-费休法在油脂产品水分测定中的应用简介

由于有机物中水分的存在,影响有机物的性质和有机物反应的进行。因此,在有机化工生产过程中,对原料、中间产品、成品都要测定其水分,需要根据试样的组成、性质、含水量等选择合适的测水方法。通常有机物水分的测定选用卡尔-费休法,卡尔-费休法基本原理是利用碘氧化二氧化硫时需消耗定量水的原理,用电位滴定中的永停终点法确定终点;滴定剂为卡尔-费休试剂,仪器为卡氏水分仪,操作简单快速,该方法广泛用于有机物中的水分测定。油脂产品有脂肪酸、脂肪胺等,通过试验,卡尔-费休法是测定这类产品水分比较适用的方法。     

卡尔-费休库仑法在油品水分测定中的探讨

油品水分检测是油品基础性能检测的重要指标,油中水分会对正常的运行设备造成严重威胁的原因是加速了油品各项性能的劣化,缩短了仪器设备的寿命。有关油品中水分含量的测定已有较多报道,相对其他方法,卡尔-费休库仑法仪器价格便宜,分析速度快,耗时短。本文以卡氏库仑法为依据,来探讨对水分测定的影响。结果表明用卡尔-费休库仑法测定油品水分是比较经典的方法。正确使用仪器以及维护保养对测定的准确度是很重要的。     

库仑法测定复混肥中的游离水

利用卡尔·费休试剂的库仑法测定水分,已有文献介绍。而应用库仑法测定复混肥中的游离水分尚未见文献报道。我们使用二氧六环试剂萃取复混肥中的游离水,然后利用 KF 库仑仪进行测定,取得了满意的结果。     

塑料—聚酰胺(PA)水分含量的测定ISO 960:1988(E)

1 范围本国标准规定了聚酰胺和多聚酰胺颗粒与已精加工制品水分含量的测定方法,本方法适用于测定水分含量高于0.01％(mm)的产品。 2 参照标准 ISO760:1978 水分的测定—卡尔·费休法(通用方法)。     

醛、酮类有机溶剂中水分的测定

探讨了改进的卡尔-费休试剂对醛、酮类有机溶剂中水分的测定。用乙二醇甲醚、吡啶、二氧化硫和碘配制成卡尔-费休试剂,合理设置卡尔-费休滴定仪参数,测定戊醛中的水分。改进的卡尔-费休试剂测定戊醛中的微量水分准确度和精密度较好。乙二醇甲醚代替甲醇的卡尔-费休试剂在测定醛、酮类有机溶剂中水分的结果稳定性好、可靠性高、方便快捷,值得进一步推广使用。     

改进卡尔-费休法测定氯化氢甲醇溶液中的水分

建立了改进卡尔-费休法，并用改进卡尔-费休法对氯化氢甲醇溶液中的水分进行测定。结果表明：改进卡尔一费休法是经济、快速、简便的方法，回收率99-102％，变异系数1．93％。     

VCM中微量水的测定方法及探讨

利用卡尔.费休库仑法的原理,使用LG-5型液态烃闪蒸气化取样进样器,测定经固碱干燥系统干燥的精馏VCM中的水分含量,其平行分析数据误差小于20×10-6。     

影响卡尔·费休法测水的因素

1935年费体提出了一种测定水的特效方法───卡尔·费休容量法，史密斯对这个方法反应的化学计量进行了较详细的研究后得出，在测水反应时，1mol水需要1mol碘、1mol二氧化硫、3mol吡啶和1mol甲醇。还提出如果没有甲醇共存时，则水或其他任何合活泼氢的化合物都能代替甲醇与中间化合物反应，这样就会扰乱化学反应的化学计量，使这个反应对水没有特殊的选择性。此外，没有甲醇共存时，试剂溶液会迅速变质，而且滴定终点也不敏锐。因此，在卡尔·费休试剂中必须含有甲醇或者另外一种合适的含有活泼氢的溶剂。以后迈耶又提出了卡尔·费休库仑法…     

气相法二氧化硅应用机理及特性

主要介绍了气相法二氧化硅在液态体系、干燥体系、固态体系中的作用机理；气相法二氧化硅在应用中的特殊性能；以及比表面积、pH、含水量、添加量、表面处理程度等气相法二氧化硅各项物理性能对应用性能的影响。     

Preparation of nanosilica reinforced waterborne silylated polyether adhesive with high shear strength

Waterborne adhesives are extremely environment‐friendly but unfortunately deficient in mechanical properties. In this article, nanosilica, stemming from tetraethyl orthosilicate (TEOS), silica sol, and/or fumed silica powder, was employed to reinforce the waterborne silylated polyether adhesives. Effects of TEOS content, silica sol content, and the type and content of fumed silica on the shear strength of the adhesive were investigated using a scanning electronic microscope and an electronic instron tester and the strengthening mechanisms of different silica source were discussed. All the shear strengths of silylated polyether adhesives first increased and then decreased as TEOS content, silica sol content or fumed silica content increased. Colloidal silica particles was less efficient than fumed silica particles for reinforcing the polyether adhesive but can increase the shear strength of hydrophobic fumed silica embedded adhesive. Comparing the adhesives with the hydrophilic fumed silica (HS‐5) or the extremely hydrophobic fumed silica (TS‐720), the adhesive with moderate hydrophobic fumed silica (TS‐610) had the highest shear strength. The maximal shear strength of 2.5 MPa was achieved when TEOS, silica sol, and fumed silica were combined. It seemed that TEOS, silica sol, and fumed silica played crosslinking (with polyether chain), dispersing (for fumed silica), and reinforcing roles on waterborne adhesive, respectively. This reinforcing mechanism opened a new way to fabricate waterborne adhesives (or coatings) with high performances. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

气相白炭黑对氟橡胶／硅橡胶共混胶性能的影响

采用气相白炭黑补强氟橡胶／硅橡胶共混胶。研究了气相白炭黑的用量和比表面积对氟橡胶／硅橡胶共混胶的力学性能、耐热老化性能和耐油性能的影响,并采用SEM观察了共混硫化胶的拉伸断面形貌。研究表明,随着气相白炭黑的用量从0份增加到50份,气相白炭黑的比表面积从120m^2·g^-1增大到380m^2·g^-1,共混胶的力学性能和耐油性能提高,而耐热老化性能下降;当气相白炭黑用量为40份,且比表面积为220m^2·g^-1时,共混硫化胶具有较好的综合性能。SEM照片表明,随着气相白炭黑用量增大,其在氟橡胶／硅橡胶共混胶中的分散均匀性下降;当气相白炭黑比表面积为220m^2·g^-1时,气相白炭黑的分散性较好。     

Transmittance and mechanical properties of PMMA-fumed silica composites

The transmittance, flexure strength, Young's modulus, and Vickers hardness of poly(methyl methacrylate) (PMMA), filled with fumed silica, was measured. Transmittance decreased with increasing content of filler. At 2 vol % filler content, composites had a higher transmittance with a lower surface area of fumed silica (larger primary particle size) because the lower surface area filler was better dispersed. At 4 vol % filler content, composites had a higher transmittance with a higher surface area fumed silica (smaller primary particle size). Flexure strength and Young's modulus of the composites was measured using three point bending. Addition of fumed silica led to a decrease of strength. Also, addition of fumed silica led to an increase of Young's modulus and Vickers hardness. © 1992 John Wiley & Sons, Inc.     

Comparative Properties of Hydrophilic and Hydrophobic Fumed Silica Filled Two-Component Polyurethane Adhesives

Two fumed silicas, one hydrophilic and another hydrophobic, were added to a two-component polyurethane (PU) adhesive and their properties compared. The filled polyurethanes were characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and water and diiodomethane contact angle measurements. The adhesive strength was evaluated from single lap-shear tests of solvent wiped stainless steel/polyurethane adhesive joints. The fumed silicas were well-dispersed in the polyurethane matrix as bundles of nanometric spherical silica particles. However, some micron size agglomerates of fumed silica appeared in the filled polyurethane. The addition of fumed silica favoured the degree of phase separation between the hard and the soft segments in the polyurethane. The polyurethanes were not fully cured under the conditions used in this study and the addition of fumed silica inhibited the curing reaction; the extent of the curing reaction was not affected by the hydrophilic or hydrophobic nature of the fumed silica. The filled polyurethanes were further cured during DSC experiments and this was noticed by the appearance of the melting of the hard segments and the displacement of the second glass transition to a higher temperature. On the other hand, the addition of fumed silica increased the wettability and the surface energy of the polyurethane; this increase was mainly due to an increase in the polar component of the surface energy. The increase in surface energy is somewhat more marked in the case of the hydrophilic silica filled polyurethane, indicating that the polarity of the fumed silica affected the surface properties of the polyurethane. Finally, the addition of the hydrophilic fumed silica increased the adhesion of the filled polyurethane adhesive to stainless steel which was in agreement with the higher surface energy of the hydrophilic fumed silica filled polyurethane.     

气相二氧化硅改性激光全息烫印胶的性能研究

将气相二氧化硅分散于醋酸丁酯中,取配方量的分散液对激光全息热烫印胶粘剂进行共混改性。通过旋转黏度计、万能材料力学试验机、烫金机测试了二氧化硅加入量对胶粘剂黏度、剪切强度以及烫印效果的影响。结果表明,当气相二氧化硅加入量为10％时,热烫印胶粘剂的综合性能最好。     

Thermal and Morphological Properties of Polypropylene/Styrene-Butadiene-Styrene Nanocomposites

Polypropylene/styrene-butadiene-styrene fumed silica nanocomposites were mixed in a twin screw Brabender Plasticorder, the weight percent of the SBS was varied at (0, 5, 10, 20, and 40), and the fumed silica content was varied at (0, 0.05, 0.1, 0.5, 1, and 2) wt%. The thermal and morphological properties of these nanocomposites were studied using a differential scanning calorimetry and a polarized light microscopy. It has been found that the addition of styrene-butadiene-styrene or fumed silica nanoparticles alone to polypropylene did not change the melting temperature while the existence of both elements changed the melting temperature of polypropylene slightly. Also, increasing the percentage of fumed silica nanoparticles leads to an increase in the crystallization temperature while styrene-butadiene-styrene increment has no effect. The melting peaks obtained by the differential scanning calorimetry revealed that increasing the styrene-butadiene-styrene content reduces the percentage crystallinity as a result of increasing the amorphous portion. The addition of styrene-butadiene-styrene to polypropylene has a very slight effect on the relative percentage crystallinity when calculations are performed based on the quantity of polypropylene within the composite. Although fumed silica nanoparticles aided and accelerating the nucleation step but it could not increase the percentage crystallinity of polypropylene beyond the percentage crystallinity of neat polypropylene.     

Interaction Between Fumed-Silica and Epoxidized Natural Rubber

Epoxidized natural rubber (ENR)/fumed silica vulcanizates were prepared by mechanical mixing method. Fumed silica content can affect mechanical properties of the composites, and ten parts per hundreds of rubber (phr) fumed silica lead to the best tensile strength. The interaction between ENR and fumed silica was characterized by Kraus equation, crosslink density (tested by NMR), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and scanning electron microscope (SEM). The results showed that the dispersion of silica in ENR was better than in natural rubber (NR), hydrogen bond was produced between ENR and fumed-silica in ENR/silica blends, and glass transition temperature of ENR/silica vulcanizate was higher than pure ENR vulcanizate. TGA and DMA confirmed that there was intense interaction between ENR and silica.     

聚碳酸酯微粉/气相白炭黑杂化增强硅橡胶

利用磨盘形力化学反应器常温粉碎制备了聚碳酸酯（PC）微粉，在硅橡胶的常规补强体系中，引入PC微粉部分代替白炭黑，实现了对硅橡胶的杂化增强，在一定程度上改善了硅橡胶复合材料的力学性能。考察了PC微粉添加量、粒径以及表面处理白炭黑对硅橡胶复合材料力学性能的影响。结果表明，用PC微粉部分代替白炭黑，可以大幅度提高硅橡胶复合材料的断裂伸长率，从230％提高到最大320％左右，撕裂强度从12．3kN／m提高到最大14．6kN／m，复合材料的硬度显著降低，从78降低至68，白炭黑经硅烷偶联剂处理后，硅橡胶复合材料的硬度减小为63。     

Preparation and pervaporation performances of fumed‐silica‐filled polydimethylsiloxane–polyamide (PA) composite membranes

Fumed‐silica‐filled polydimethylsiloxane (PDMS)–polyamide (PA) composite membranes were prepared by the introduction of hydrophobic fumed silica into a PDMS skin layer. The cross‐sectional morphology of these filled composite membranes was observed with scanning electron microscopy. Their pervaporation performances were tested with aqueous ethanol solutions at 30, 35, and 40°C. Increasing the amount of the fumed silica resulted in significantly enhanced ethanol permeability of the membranes. When the content of the fumed silica in the PDMS skin layer was 20 wt %, the ethanol permeability increased to nearly twice that of the unfilled PDMS–PA composite membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007