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1.
From the practical standpoint of fabric softener formulation, a comparative study was made on adsorption behavior toward fabrics of binary systems consisting of di(hydrogenated tallow) dimethyl ammonium chloride (purified Arquad 2HT) and typical polyoxyethylenated nonionic surfactants which are commonly used as auxiliary agents for softeners. Soxhlet extraction of treated fabrics and quantitative analysis by high-performance liquid chromatography (HPLC) gave significant results indicating many of these nonionic surfactants, assumed to be inherently unadsorbable in rinse-cycle treatment, were highly adsorbable even at a high bath ratio by being applied with the water-insoluble cationic surfactant. Moreover, it was also disclosed that the hydrophobic structure of nonionic surfactants is another factor, other than hydrophobicity, determining adsorption. Furthermore, the mechanism of this nonionic adsorption was elucidated on the basis of results of structural analyses of binary dispersions by differential scanning calorimetry (DSC), X-ray diffraction, electron spin resonance spectroscopy (ESR) and transmission electromicroscopy (TEM) in addition to partition measurements of the surfactants into the dispersed and the continuous aqueous phases. It was concluded that the primary driving force for this nonionic adsorption is an association with the lamellar of Arquad 2HT and that the cationic vesicles act as “anchors” in adsorption.  相似文献   

2.
The effect of water on the flow behavior of glass microspheres dispersed in mineral oil was investigated for various levels of water, particle volume fractions, and particle sizes. The addition of small amounts of water leads to large increases in viscosity due to the formation of water bridges between particles that give rise to capillary forces between the particles. The capillary forces between the particles also make the flow profile highly shear‐thinning across the range of particle volume fractions that were studied (0.10 to 0.25). The presence of water leads to a significant effect of particle size, and the viscosity of dispersion goes through a maximum as the amount of water is increased. Two hydrophobic surfactants, Span 80 and Arquad 2HT, were found to reduce the viscosity of the dispersions with added water, but the mechanism and extent of viscosity reduction differed. © 2010 American Institute of Chemical Engineers AIChE J, 2011  相似文献   

3.
吴启强  包永忠 《化工学报》2011,62(4):1130-1135
采用原位悬浮聚合和熔融加工制备了不同纳米水滑石含量的偏氯乙烯-丙烯酸甲酯(VDC-MA)共聚物/纳米水滑石复合材料,并通过高温炭化和模板消除得到多孔炭材料。采用电镜、X射线衍射、N2吸脱附法表征了复合材料和多孔炭的结构。结果表明,纳米水滑石含量≤6.25%(质量)时,纳米水滑石基本以初级粒子均匀分散在VDC-MA共聚物基体中,并在炭化过程中转化为金属氧化物;金属氧化物可经酸洗去除,起到模板致孔作用;同时VDC-MA共聚物炭化过程形成大量微孔,因此得到的多孔炭具有微孔和中孔分布。当炭化温度较低时(600~700℃)相似文献   

4.
苏虎  宋晓玲  黄东  包永忠 《塑料助剂》2012,(2):36-39,52
采用原位悬浮聚合制备了水滑石和锡酸锌复合改性的聚氯乙烯(PVC)树脂,研究了水滑石和锡酸锌在PVC基体中的分散及其含量对邻苯二甲酸二异辛酯(DOP)增塑PVC极限氧指数、燃烧烟密度的影响。发现通过原位聚合可以实现水滑石和锡酸锌粒子的良好分散;DOP含量增加使PVC的极限氧指数降低,燃烧烟密度增加;而水滑石和锡酸锌含量增加,使增塑PVC的极限氧指数提高,燃烧烟密度降低。  相似文献   

5.
CO甲烷化在煤制天然气技术中起着重要作用,Ni基催化剂作为目前研究最多的甲烷化催化剂,仍存在低温活性差、高温易烧结和易积炭等问题。针对这些问题,采用改进的溶剂蒸发诱导自组装方法,设计制备了不同含量Nd物种修饰的Ni-Nd-Al三元有序介孔甲烷化催化剂。采用N2-物理吸附、X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等分析方法对反应前后催化剂的结构和形貌进行了表征,并考察其CO甲烷化反应催化性能。结果表明,制备出的Ni-Nd-Al甲烷化催化剂均具有有序介孔结构,Ni和Nd物种均匀分布在孔道内。适量Nd物种的加入有助于减小Ni颗粒的尺寸,提高其分散度和对H2的吸附能力,进而提升催化剂的活性。有序介孔结构的限域效应有助于提高催化剂抗烧结和抗积炭能力。  相似文献   

6.
SiO2- and Al2O3-supported MoS2 and WS2 catalysts were prepared to exploit the evaluation technique of the edge dispersion of MoS2 and WS2 particles. A chemical vapor deposition (CVD) technique using Co(CO)3NO as a probe molecule was used for the evaluation. Results were compared with those from conventional techniques such as NO adsorption and TEM. A proportional correlation was obtained between the amount of NO adsorption and the amount of Co atoms accommodated by the CVD technique on WS2/SiO2 and WS2/Al2O3 catalysts, demonstrating a selective location of the Co atoms on the edges of WS2 particles, as previously established for MoS2 catalysts. A comparison of the amounts of NO adsorption and Co accommodation on MoS2 and WS2 catalysts suggested a 70% higher density of sulfur vacancy on MoS2 particles than on WS2 particles regardless of the support. The Co atoms on the edges of MoS2 and WS2 particles showed the identical NO adsorption property. We propose that Co(CO)3NO can be used as a probe molecule to evaluate and directly compare the edge dispersions of MoS2 and WS2 catalysts. The dispersion of MoS2 particles was about two times higher than that of WS2 particles with the SiO2-supported catalysts. With the Al2O3-supported catalysts, MoS2 and WS2 particles were dispersed to a similar extent but much more highly dispersed than the counterparts in the SiO2-supported catalysts. The evaluation of the edge dispersion of MoS2 and WS2 particles by means of TEM may pose problems when SiO2- and Al2O3-supported catalysts are compared. The edges of unpromoted MoS2 particles exhibited a significantly higher intrinsic activity for the HDS of thiophene than those of WS2 particles.  相似文献   

7.
Stability of pigment and resin dispersions in waterborne paint   总被引:1,自引:0,他引:1  
The stability of a colloidal dispersion in a waterborne paint system, which consists of dispersed pigment and polymeric particles (dispersion or emulsion) along with a water-soluble acrylic polymer, was investigated. It was found that adsorption of appropriate ultrafine particles to the relevant particles could stabilize these particles against flocculation, leading to lower viscosity and yield value. The gloss and smoothness of the resultant films are notably improved. As the stability of the colloidal particles in an aqueous system is strongly dependent on the electrostatic effect, the effect was evaluated by measuring the ζ-potentials of the relevant colloidal particles. The ζ-potential is the electric potential on the outside of the surface layer, which includes the counterions around the particle. The ζ-potentials of a series of pigments in a solution of a water-soluble polymer were determined. By arranging the pigments according to their ζ-potentials, an order of basicity-acidity was established for pigments in a waterborne system, and the order was found to be different from that of solventborne systems, thought to be due to adsorbed counterions. After dispersing the pigment sufficiently with an appropriate polymer dispersant, ultrafine particles (of size under 0.05 μm) of lower refractive indexes were adsorbed to the surface of the pigments and polymeric particles. The adsorption layer of ultrafine particles can modulate the ζ-potentials of various colloidal particles to bring them into a certain range, so that the co-flocculation tendency between different colloids is remarkably diminished providing quite stable paint compositions by both electrostatic and steric hindrance effects.  相似文献   

8.
Pd‐hydrotalcite (abbreviated as Pd(HT)) was dispersed on HMS (hexagonal mesoporous silica) by synthesizing Pd(HT) in an HMS suspension, and the resultant product (Pd(HT)/HMS) was used as a catalyst precursor for methanol decomposition to synthesis gas. The IR spectra of Pd(HT)/HMS showed all the bands of Pd(HT) and HMS with little shift, which indicated that Pd(HT) was synthesized in the Pd(HT)/HMS. Pd(HT)/HMS did not show the XRD pattern of Pd(HT) when the mass ratio of Pd(HT) to HMS was from 2/1 to 1/2. This indicated that Pd(HT) was formed in very small particles in the Pd(HT)/HMS after dispersion. Two endothermic peaks of Pd(HT) in the DTA curve shifted to lower temperatures in the Pd(HT)/HMS because the small Pd(HT) particles formed in the Pd(HT)/HMS were easily collapsed by heat treatment. Pd(HT)/HMS was thermally decomposed and reduced to form a supported Pd catalyst (abbreviated Pd(Mg(Al)O)/HMS) for methanol decomposition. Pd(Mg(Al)O)/HMS at 3.6 wt% showed a 52.5% conversion which was much higher than those over 3.6 wt% Pd(Mg(Al)O) (34.7%) and 3.6 wt% Pd/HMS (13.7%) for methanol decomposition at 523 K. The conversions of methanol over Pd(Mg(Al)O) and Pd/HMS increased with the increase in Pd loadings from 3.6 to 15 wt% and decreased when the Pd loadings were over 15 wt%. In contrast, the conversion over Pd(Mg(Al)O)/HMS increased with the increase in Pd loading even when the Pd loading was up to 30%. 30 wt% Pd(Mg(Al)O)/HMS showed a 91.7% conversion which was about twice that over 15 wt% Pd(Mg(Al)O) (47.1%) at 523 K. The Pd(Mg(Al)O)/HMS catalyst showed a larger BET surface area and Pd metal surface area than those of Pd(Mg(Al)O). By characterization using XPS analyses, the metal–support interaction between small Pd and small Mg(Al)O became stronger in the Pd(Mg(Al)O)/HMS catalyst. Large surface area, high Pd dispersion and strong metal–support interaction caused the high catalytic activity for methanol decomposition to synthesis gas over the Pd(Mg(Al)O)/HMS catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

9.
羧甲基纤维素钠改性零价铁在石英砂中的迁移能力   总被引:1,自引:0,他引:1  
殷其亮  李筱琴  李瑛  肖阳 《化工进展》2013,32(7):1598-1603
利用羧甲基纤维素钠(CMC)对零价铁进行改性,通过Zeta电位、粒型粒度和沉降曲线的变化探讨改性剂添加量影响零价铁分散的机理,同时考察改性剂添加量、流速和多孔介质类型对零价铁迁移的影响。结果表明,CMC对零价铁的分散机理符合DLVO模型,静电空间位阻带来的势垒增加量与CMC添加量成正相关,能促进零价铁的分散;经500%CMC(CMC与零价铁的质量比)改性的零价铁分散性能最好,成颗粒状、吸光度在90 min下降31%。受零价铁与石英砂作用能、填充介质的吸附位点和剪切力的影响,零价铁的迁移能力随着CMC添加量的增多,填充介质粒径的增大和流速的增加而增强。  相似文献   

10.
The present article is concerned with the temperature‐conductivity characteristics of blends consisting of polyisothianaphthene (PITN) particles and a soluble poly(3‐hexylthiophene) (P3HT). PITN was synthesized by direct conversion of 1,3‐dihydroisothianaphthene (DHITN) monomer using N‐chlorosuccinimide (NCS) as an oxidation/dehydrogenation reagent. The high conductivity and thermal stability of the doped and dedoped PITN were confirmed. Microscopic investigation by scanning electron microscopy (SEM) showed that the as‐prepared PITN exhibited diversified shapes and sizes, with large rectangular particles having an average size of 2 ~ 5μm and fine round particles ranging from 0.1 to 0.3 μm. The PITN particles were blended with the chemically synthesized P3HT as a high conductivity component to improve the conductivity and simultaneously maintain the positive temperature coefficient (PTC) effect of the original P3HT near its melting point. The temperature‐conductivity characteristics for PITN‐P3HT blends with various PITN contents showed that a blend having both a high conductivity (nearly 3 ~ 4 orders higher than that of the original P3HT) and a good PTC intensity could be obtained with a PITN content of 20 ~ 25%. The different temperature‐conductivity behavior of P3HT blends filled with PITN as compared to other conducting particles, for example, carbon black, was explained by its unique dispersion structure due to a relatively higher adhesive interaction of PITN particles with the P3HT matrix during the precipitation process. The results from heating recycles revealed that the PTC effect of PITN‐P3HT blends was not just related to the conductivity decrease of the P3HT matrix, arising from the conformational change of the conjugated backbone during the melting, but also to the dilution effect of the conducting percolation network due to the mobility of PITN particles induced by the viscosity decrease of the P3HT matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1848–1854, 2005  相似文献   

11.
The temperature–conductivity characteristics of poly(3‐hexylthiophene) (P3HT) composites filled with P3HT‐grafted indium tin oxide (ITO) particles were investigated in this work. The ITO particles were first treated with a silane coupling reagent of 3‐aminopropyltriethoxysilane (APS), and then thiophene rings were introduced through a condensation reaction between the ending amino groups of APS and the carboxylic groups of thiophene‐3‐acetic acid. The composites were prepared by the polymerization filling of the 3‐hexylthiophene (3HT) monomer with the thiophene‐ring‐introduced ITO particles. Elemental analysis, Fourier transform infrared, and X‐ray photoelectron spectroscopy were used to confirm the grafting reaction on the ITO surface. The longer the polymerization time was or the higher the 3HT/ITO feeding ratio was, the more P3HT was grafted. The influence of the grafted amount on the electrical properties of ITO particles was attributed to the wrapping effect formed by the grafted P3HT on the surface of the ITO particles. The conductivity change of the P3HT‐grafted ITO/P3HT composites was proved to be subject to the change in the average gap width of ITO interparticles, which was determined by the filling ratio of P3HT to ITO in the polymerization and the volume expansion effect of a P3HT thin film between neighboring ITO particles during the heating process. In comparison with the ungrafted ITO/P3HT composites, the grafting treatment enhanced the interaction between the particles and polymer matrix, and this was helpful for obtaining a more homogeneous dispersion structure for the composites and thus afforded a higher positive temperature coefficient intensity and better reproducibility. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1881–1888, 2006  相似文献   

12.
Some grades of cis-1,4-polybutadiene contain dispersed crystalline particles made up of a block copolymer having amorphous cis-1,4- and crystalline 1,2 blocks. The particles are known to enhance the strain-induced crystallization of cis-1,4 matrix rubber. The deformational behavior was examined by dynamic shear measurements at small deformation and tensile stress–strain measurements at large deformation. In the shear measurements (linear behavior), the temperature dependence of the shift factor in the time-temperature superposition has been evaluated. The higher temperature dependence was observed for the lower crystalline particle content and higher degree of branching of the matrix rubber. The presence of the crystalline particles resulted in the viscosity enhancement like that expected from the dispersed particles. In the tensile measurements (non-linear behavior), the rubbers showed strain softening. The higher degree of strain softening was observed for the higher amount of the crystalline particles and lower degree of branching. The strain softening is a result of the crystalline particles facilitating the elongation. Because these particles posses the branches which are cis-1,4 chains of the block copolymer, the branches are lubricating the system during the stretching. The length of the branches must be short enough so as to produce no significant entanglement constraint. This observation is in accord with the previous one that a relatively long branch gives strain hardening, whereas a relatively short branch gives strain softening. The strain softening was found to enhance the strain-induced crystallization. This conclusion is opposite to what one might expect from the entanglement constraints by the long branches, forcing the orientation of the chains, and thus enhancing the strain-induced crystallization. © 1996 John Wiley & Sons, Inc.  相似文献   

13.
Softening phenomenon of fabrics stiffened with eco-friendly polymeric stiffening agents often occurs in service conditions, leading to a deteriorated stiffening style. It is highly desired to find the key factors that induce the softening of stiffened fabrics and to understand the softening mechanism. In this work, polyester fabrics and poly(vinyl acetate) (PVAc)-based stiffening agent were chosen as the typical fabrics and polymeric stiffening agent, respectively. The stiffness value, a sensitive style index for the stiffening effect of fabrics, was selected to evaluate the variation of fabric stiffening effect during storage. A phenomenon of rapid softening was observed in the fabrics stiffened with various amounts of PVAc-based stiffening agent. The stiffness value of stiffened fabrics decreased with the increase of hygroscopic amount. According to the hygroscopic kinetic data, the moisture-induced plasticization effect of stiffening agent film, and the detachment of stiffening agent film from the fibers caused by the moisture-induced weakening of interfacial interaction between the film and fiber, a possible softening mechanism of polymer-stiffened fabrics was proposed. The hygroscopic-drying cyclic experiments showed that the softening of stiffened fabrics was induced by the reversible plasticization effect and the irreversible interfacial damage between the film and fiber.  相似文献   

14.
采用双螺杆挤出机辅以活化剂制备活化废轿车轮胎胶粉(GTR),用其改性沥青或与苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)复合改性沥青。研究了活化GTR的溶胶、凝胶含量,考察了活化GTR改性沥青和活化GTR/SBS复合改性沥青的基本性能及微观形貌。结果表明,热剪切以及添加活化剂均能提高GTR的溶胶含量,使脱硫降解程度增大;用活化GTR改性沥青,改性沥青的针入度大幅增大,软化点、弹性回复、黏度明显降低;用活化GTR/SBS复合改性沥青,随着活化GTR含量的增大,改性沥青的软化点升高,针入度、延度、弹性回复降低,但经旋转薄膜老化后延度提高,耐老化性能提高;活化GTR在沥青中的粒径明显减小,分散性得到改善,而活化GTR/SBS复合改性沥青时,GTR均匀分散于SBS的网络结构中。  相似文献   

15.
The polyacrylamide–montmorillonite “water in water” (PAM-MMT W/W) emulsion was prepared by dispersion polymerization method in the presence of organo-montmorillonite (OMMT). Based on the analysis of the polymerization process, the structure of material was investigated using thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy experiments. Here, the dispersion was determined to be a blend of PAM W/W emulsion and PAM network interspersed by MMT particles, this unique structure of the material was considered to provide better adsorption ability compared to PAM without MMT. Therefore, a PAM-MMT adsorbent was made from the PAM-MMT W/W emulsion, and its adsorption capacity toward Cr(III), one of the heavy metal pollutants from the tannery waste was investigated. The PAM-MMT nanocomposite was demonstrated to have good Cr(III) removal performance, the maximum adsorption capacity of the nanocomposite was found to be 59.74 mg/g at a pH of 5.5 and temperature of 70°C. Results show that pseudo-second-order kinetic model and Langmuir isotherm were applicable for Cr(III) adsorption.  相似文献   

16.
庞煜霞  李媛  周明松  陶家媛  高菲 《化工学报》2016,67(11):4858-4865
为了揭示羧甲基化碱木质素CML较磺化碱木质素(SAL)对农药具有更好分散性能的原因,测定了CML和SAL的亲水基含量、相对分子质量及纯水在木质素涂层的接触角,发现CML的亲水性弱于SAL。对比了两种木质素分散剂在多菌灵颗粒上的吸附等温线,发现CML的吸附量比SAL大,并采用Langmuir、Freundlich方程进行拟合,可知CML的吸附能力大于SAL,说明木质素与农药之间的吸附可能以疏水吸附为主。进一步采用Gaussian模拟计算木质素分散剂与多菌灵的π-π吸附作用力,结果表明羧甲基化碱木质素更易与农药形成稳定π-π作用,进一步促进吸附。亲水性较弱的CML由于与农药具有更强的吸附亲和力,因而吸附量大,对农药颗粒Zeta电位的提高更大,从而具有更好的分散性能。  相似文献   

17.
This study aims to explore the joint effects of specific β‐nucleation and rubber dispersion on morphology and mechanical behavior of materials derived from isotactic polypropylene. A β‐nucleator (N,N′‐dicyclohexylnaphthalene‐2,6‐dicarboxamide) and an amorphous EPM rubber were used for the modification of isotactic polypropylene. Four samples were investigated: neat polypropylene, the same polymer modified with 0.03 wt % of β‐nucleator or with 15 wt % of dispersed rubber particles, and finally polypropylene containing both the β‐nucleator and the rubber particles. Tensile and impact behavior were followed at room and cryogenic temperatures. It has been observed that the β‐nucleation and rubber modification have brought about a similar macroscopic softening effect on the tensile mechanical behavior. Microscopy of fracture surfaces, however, has shown different toughening mechanisms caused by specific nucleation on one hand and by rubber dispersion on the other. While a distinct synergy effect of nucleation and rubber modification on the resulting toughness was found at low temperature, no such cooperative effect manifested itself at room temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3539–3546, 2007  相似文献   

18.
The effect of solvent on adsorption of the multi-walled carbon nanotube (MWNT) onto poly(methyl methacrylate) (PMMA) microspheres is examined and then their electrorheological (ER) behavior under an applied electric field when dispersed in a silicone oil is observed, using the MWNT which was initially modified with carboxylic acid functional groups on its outside wall through an oxidation treatment (c-MWNT). The c-MWNT was successfully incorporated onto the PMMA microsphere surface in either Di-water or methanol, while the adsorption state of the c-MWNT is strongly dependent on the solvent used. The dense and well dispersed c-MWNT is found to be more strongly attached onto the surface of PMMA microspheres when prepared in Di-water than in methanol. It is believed that hydrogen bonding component in the Hansen solubility parameter is a principal factor determining dispersion state of the c-MWNT in the solvent, because the nanotubes used have carboxylic acid functional groups on their surface forming hydrogen bonding between c-MWNT and the solvent. Moreover, c-MWNT/PMMA microsphere as an ER material dispersed in a silicone oil is observed to exhibit typical ER characteristics of fibril structure under an applied electric field, and the ER characteristics are found to be influenced by the conductivity of c-MWNT/PMMA microspheres.  相似文献   

19.
The effect of fillers and the structure of matrix rubbers on the tensile stress—strain behavior were examined with unvulcanized compounds of cis-1,4-polybutadiene. The matrix rubbers were CB11, CB22, and VCR412, which had been studied previously. The fillers were two different carbon blacks (N110 and N330) and silica. The tensile modulus was found to be separable into the time-dependent and strain-dependent functions. The time dependence was represented with a universal form, the observed time being reduced with the extension ratio. The strain-dependent function was affected by material variables. The function indicated a strain-softening tendency. The extent of softening is related to the softening or hardening observed with the unfilled matrix rubbers, which are in turn related to the length and degree of branching and to the presence of crystalline particles of 1,2-polybutadiene. However, carbon black evidently accentuates the softening tendency. Also, poorer dispersion results in higher softening. The silica-filled compound had a poor dispersion. With the addition of a coupling agent, the dispersion improved but the compound behaved like it was crosslinked. The strain-induced crystallization previously observed with CB11 and VCR412 gum rubbers (but not with CB22) appears as significant differences of the moduli of the compounds. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1445–1453, 1997  相似文献   

20.
以单层分散理论为指导,研究了氯化钙在大球硅胶上的单层分散、氨吸附及吸附稳定性。结果表明,对于焙烧分散法,氯化钙/大球硅胶的适宜焙烧温度为500℃;对于微波分散法,适宜的微波辐射时间是20 min。焙烧样品的单层分散阈值为0.2~0.3 g/g,微波样品的单层分散阈值为0.3~0.4 g/g。将吸附量较大的样品进行比较,在35℃下,担载量为0.4 g/g的焙烧样品氨吸附量为0.35 g/g;担载量0.5 g/g的微波样品氨吸附量为0.41 g/g。微波样品的氨吸附量大于焙烧样品。吸附-脱附循环实验表明,2种分散法所得复合吸附剂同样具有较好的吸附稳定性。  相似文献   

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