Effect of phenolic resin structure on the bonding properties of nitrile rubber-based adhesives

Three phenolic resins were used to study the effect of resin structure and its percentage content on the bonding properties of nitrile rubber-based adhesives. The phenolic resins studied are derived from phenol, resorcinol and para-t-butyl phenol, and are of novalac type. These resins were characterized by infra-red and thermal studies. Several formulations were prepared by varying the phenolic resin/nitrile rubber ratio and these formulations were tested for viscosity and bonding properties. At a given resin-to-rubber ratio, the viscosity for resorcinol-formaldehyde resin was higher than phenol-formaldehyde resin followed by para-t-butyl phenol-formaldehyde resin. The peel strength of nitrile rubber-based adhesive prepared from resorcinol-formaldehyde resin was higher than adhesives that from para-t-butyl phenol-formaldehyde resin followed by phenol-formaldehyde resin. The lap shear strength of nitrile rubber-based adhesive containing para-t-butyl phenol-formaldehyde resin was higher than of adhesives containing the other two resins. The trend observed in peel strength could be explained on the basis of hydrogen bonding between hydroxyl groups of phenolic resin (adhesive) and hydroxyl groups of the starch-coated canvas cloth (adherend), whereas the trend observed in lap shear strength could be explained on the basis of extent of linearity in the resin structure.     

Lindane adsorption isotherms interpreted in terms of interaction free energies with porous media

Lindane adsorption isotherms on silica sand and alluvial loam were investigated by batch and column experiments and related to lindane interaction free energies with the porous media. These interaction free energies were highly dependent on the physico-chemical characteristics of lindane and the porous media and could be calculated by their surface thermodynamic properties. Silica sand displayed a single adsorption domain and lindane had a linear adsorption isotherm on silica sand. In contrast, alluvial loam exhibited dual adsorption domains, which could be interpreted by two linear adsorption isotherms. For heterogeneous porous media with multiple adsorption domains, such as alluvial loam, lindane first adsorbed onto domains of high adsorption potentials. When these domains were occupied, lindane began to adsorb onto domains of low adsorption potentials.     

Effects of moisture and temperature ageing on reliability of interfacial adhesion with black copper oxide substrate

The reliability of adhesion performance of bare Cu, as-deposited and surface-hardened black oxide coatings on Cu substrates was studied. The interfacial adhesion with a polyimide adhesive tape and an epoxy moulding compound was measured using the button shear and tape peel tests after hygrothermal ageing in an autoclave, high temperature ageing and thermal cycles. Moisture adsorption and desorption studies at different aging times suggested that the black oxide coating was effective in reducing the moisture adsorption. The bond strengths for all substrates remained almost unchanged after thermal ageing at 150°C for 8 h. Thermal cycling between ?50°C and 150°C for 500 cycles reduced by about 20% the button shear strength of the as-deposited black oxide substrate, but it did change much the bonding performance of the bare Cu substrate. Hygrothermal ageing at 121°C/100% RH in an autoclave was most detrimental to adhesion performance because of the combined effect of elevated temperature and high humidity. The reduction in button shear strength after the initial ageing for 48 h was 50–67%, depending on the type of coating. In all accelerated ageing tests, the residual interfacial bond strengths were consistently much higher for the black-oxide-coated substrates than the bare Cu surface, confirming a higher reliability of black oxide coating. Fracture surfaces analysis of tape-peeled bare copper substrates after 500 cycles of thermal loading revealed a transition in failure mechanism from interfacial to cohesive failure. In contrast, the failure mechanism remained unchanged for black-oxide-coated substrates. The observations made from the button shear and tape peel tests were generally different because of the different fracture modes involved.     

Grafting of alkylchlorosilanes onto silica from solution for adhesion enhancement

An efficient grafting process of monofunctional alkylchlorosilanes [general formula: CH₃ (CH₂)_n-1 Si (CH₃)₂Cl with n varying from 4 to 30] onto silica surfaces was developed by varying the surface preparation and the solvent used for the deposition process. A vapor phase deposition method was considered as the reference. The grafting method was evaluated by studying the wettability and the graft densities of the resulting monolayers. The chain conformation of the monolayers was determined by comparing the thicknesses measured by SE ellipsometry and AFM, and the orientation of the chains was evaluated by FT-IR in an attenuated total reflection (ATR) mode. By comparing the solvent and vapor phase deposition methods, it was demonstrated that the deposition process had a large influence on the structure of the grafted monolayers. The same structure as that from a vapor phase method can be obtained from a solvent deposition process by a suitable choice of the solvent and by carefully carried out cleaning of the surface before deposition. The organization of the grafted layers was found to be dependent on the length of the alkyl chains; i.e. uniform and well-ordered monolayers were obtained for a 'critical' length of the alkyl chain - C18. In fact, as the alkyl chain becomes short, the resulting layers are hydrophobic and heterogeneous and do not display a preferential orientation, whereas long alkyl chains - C30 - lie on the silica surface without any organization.     

对甲基苯甲酸在大孔吸附树脂上的吸附热力学及动力学研究

研究了对甲基苯甲酸在NDA-1800和JX-101大孔吸附树脂上的静态吸附热力学和动力学行为。结果表明,在283～313 K和研究的浓度范围内,两种大孔吸附树脂吸附对甲基苯甲酸的行为符合Freundlich吸附等温方程。对甲基苯甲酸在两种大孔吸附树脂上的吸附焓变△H〈0,为放热过程;自由能变△G〈0,吸附过程能自发进行;吸附熵变△S〈0,这是因为吸附质分子从水溶液中被吸附到树脂表面后,其分子运动受到了限制,使吸附熵减少。两种大孔树脂吸附对甲基苯甲酸的速率常数都比较大,且随着温度的升高而增大。吸附活化能都比较低,吸附较容易进行。     

离子交换树脂吸附古龙酸的工艺

应用自行合成的阴离子树脂D02直接吸附发酵液中的2-酮基-L-古龙酸,并研究了其吸附的静态与动态过程.利用Langmuir和Freundlich吸附等温线方程对吸附等温线数据进行拟合,发现2种模型相关性都很好.测定了不同流速、温度、浓度以及pH条件下古龙酸在合成树脂柱中的穿透曲线,当上柱液pH为1.5、质量浓度为10 g/L、吸附温度为309 K、流速为0.35 mL/min时,每g湿树脂的动态附容量为133 mg.同时测定了不同洗脱剂、洗脱流速条件下的洗脱曲线.每g湿树脂的动态吸附容量达到了133 mg,当温度为283 K、洗脱剂为10%H2SO4-CH3OH、流速为0.2 mL/min时,洗脱收率可达65.3%.     

Synthesis and characterization of phenolic resol resin blended with silica sol and PVA

The phenolic resol resin (PF) has a wide application in industry, but its poor tensile ductility and insufficient mechanical strength have severely limited its application. To overcome these limitations, in this study, the mixtures of silica sol and poly(vinyl acohol) (PVA) were used to modify the PF. The structure, morphology, mechanical properties, and thermal stability of these hybrid materials were investigated by FTIR, SEM, tensile shear test (TSS), and TG. FTIR spectra indicated that the multiple reactive functional silanol group Si OH on the surface of SiO₂ particles reacted with PVA and PF. Compared with pure PF, the composite 50‐50‐3% exhibited the maximum shear strength which increased by 158%, whereas the elongation at break increased by 63%. Morphological results agreed well with the mechanical properties. The TG results suggested that the composite material 50‐50‐3% and pure PF had almost the same thermal stability because silica sol and PVA had opposite effects on the heat resistance of the hybrid materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The interrelationships between electronically conductive adhesive formulations,substrate and filler surface properties,and joint performance. Part I: the effects of adhesive thickness

Electronically conductive adhesives (ECAs) have received a great deal of attention for interconnection applications in recent years. Even though ECAs have excellent potential for being efficient and less costly alternative to solder joining in electronic components, they still possess a number of problems with respect to durability and design to meet specific needs. One of the issues that requires understanding is regarding the optimum adhesive thickness (AT) to be used. This study addresses this issue in relation to the formulations of the conductive adhesives and their interactions with adherend surfaces. For this purpose, two different adherends varying in surface characteristics were utilized along with three different conductive adhesive formulations with varying particle loadings, and shapes and sizes of conductive nickel fillers. Joints were also prepared with two different AT values, to gain insight into the influence of AT on the joint strength, deformation and joint conductivity. As the AT was increased, only a small reduction in failure load and ultimate displacement values were observed with unetched adherends. With etched adherends, however, a small increase in joint stretchability was evident with higher adhesive thickness tested at a lower crosshead speed. When the AT was increased, we also noted a corresponding increase in the initial joint resistance.     

Flow micro-calorimetry and FTIR studies on the adsorption of saturated and unsaturated carboxylic acids onto metal hydroxide flame-retardant fillers

Carboxylic acids, particularly fatty acids, are by far the most important surface modification systems for inorganic fillers used in the plastics and rubber industries. However, relatively little is understood regarding factors that affect their adsorption behaviour, including the interplay between acid molecular structure, adsorption conditions, and substrate chemistry. In this study, the adsorption (from n-heptane and toluene) of a range of saturated and unsaturated fatty acids, together with acrylic acid, onto aluminium and magnesium hydroxides has been investigated using flow micro-calorimetry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). With C18 saturated fatty acids, the overall heat of adsorption per unit surface area of substrate was found to be affected by the structure of the alkyl tail. The orientation of the adsorbed unsaturated fatty acids was found to be affected by the number of double bonds in the molecule. Acrylic acid was found to be very strongly adsorbing and could displace isostearic acid from the filler surface. However, isostearic acid was found to adsorb on top of the layer of aluminium or magnesium acrylate. These findings have important implications particularly for mixed fatty acid treatment methods and the choice of fatty acid treatment for metal hydroxide flame-retardant fillers.     

D301树脂动态吸附溴离子过程探究及模型拟合

研究了用D301树脂吸附岩盐矿提钾母液中溴离子的可能性,考察了吸附柱动态吸附过程中原料液溴离子初始浓度、床层高度及进料流速等因素的影响。结果表明,增加原料液溴离子初始浓度或降低进料流速能提高树脂单位饱和吸附量。当原料液溴离子初始浓度从1000 mg/L升至4000 mg/L时,树脂单位饱和吸附量从1.8 mg/L增至6.4 mg/mL。增加床层高度或降低进料流速会延长动态吸附突破时间及饱和时间,而原料液溴离子初始浓度对其没有影响。应用了Bed Depth Service Time(BDST), Thomas, Yoon-Nelson, Wolborska及Modified dose response(MDR)等五种吸附模型对动态吸附过程进行拟合,其中MDR模型的拟合效果最佳。D301树脂可用于从含有高浓度氯离子的提钾母液中提取溴离子。     

双官能基修饰的超高交联吸附树脂对2,4-二氯苯酚的吸附性能研究

合成了用2-氨基酚修饰的新型双官能基聚苯乙烯-二乙烯苯吸附树脂MOAPR-1和MOAPR-2,研究了其在288~318 K下对水溶液中2,4-二氯苯酚的静态吸附和静态脱附特征。结果表明,2,4-二氯苯酚在两种树脂上存在化学吸附现象,符合Freundlich等温吸附方程。利用半经验分子轨道法计算了几种吸附剂的近似结构和2,4-二氯苯酚的前线轨道能级,并对吸附过程进行了合理的解释。     

Polymer-bound flavins: 2. Immobilization of linear flavin-containing polyelectrolytes by adsorption onto silica

The adsorption of quaternary ammonium derivatives of linear polystyrene, containing pendant flavin groups, from aqueous solution onto nonporous silica particles was studied. It is shown that interaction takes place between the quaternary ammonium groups in the polymer and ionized silanol groups on the silica surface. Since the maximum specific adsorption was not influenced by the content of quaternary ammonium groups, relatively few quaternary ammonium groups appear to be necessary to bind the copolymers to the silica surface, probably resulting in a large fraction of segments located in loops and tails. The reactivity of the bound flavin, as estimated from kinetics of aerobic oxidation of 1-benzyl-1,4-dihydronicotinamide (BNAH) in aqueous solution, is not influenced by the adsorption process. The immobilized reactive polymer can easily be re-used several times without loss of activity, indicating that desorption of the polymer can be neglected.     

乙酰苯胺修饰的吸附树脂对2,4-二氯苯酚的吸附研究

通过后交联反应,用乙酰苯胺修饰氯甲基化的低交联大孔聚苯乙烯-二乙烯(氯球),合成了一种超高交联吸附树脂ZH-05。用活性炭GAC和Amberlite XAD-4树脂作为参照,测试了ZH-05吸附树脂对2,4-二氯苯酚的吸附性能。讨论了静态平衡吸附行为和化学吸附特征的证实。结果表明:吸附等温线都能用Langmu ir方程很好的拟合,且2,4-二氯苯酚在ZH-05吸附树脂上的吸附是一个吸热过程,吸附量随吸附温度的升高而增加,和活性炭一样,ZH-05树脂对水溶液中2,4-二氯苯酚的吸附过程中同时存在着物理吸附和化学吸附。     

Removal of acid dyes from aqueous media by adsorption onto amino-functionalized nanoporous silica SBA-3

Adsorption of acid dyes on SBA-3 ordered mesoporous silica, ethylenediamine functionalized SBA-3 (SBA-3/EDA), aminopropyl functionalized SBA-3 (SBA-3/APTES) and pentaethylene hexamine functionalized SBA-3 (SBA-3/PEHA) materials has been studied. The structural order and textural properties of the synthesized materials have been studied by XRD, FT-IR and nitrogen adsorption-desorption analysis. The adsorption capacity of the adsorbents varies in the following order: SBA-3/PEHA > SBA-3/APTES > SBA-3/EDA > SBA-3. The SBA-3/PEHA is found to have the highest adsorption capacity for all acid dyes. The adsorption mechanism which is based on electrostatic attraction and hydrogen bonding is described. Batch studies were performed to study the effect of various experimental parameters such as chemical modification, contact time, initial concentration, adsorbent dose, agitation speed, solution pH and reaction temperature on the adsorption process. The Langmuir and Freundlich isotherm models have been applied and the Freundlich model was found to be fit with the equilibrium isotherm data. Kinetics of adsorption follows the second-order rate equation.     

Insights into membrane fouling implicated by physical adsorption of soluble microbial products onto D3520 resin

Membrane fouling is a major problem in membrane bioreactors(MBRs). In this study, membrane fouling caused by membrane rejection and adsorption was study. Filtration tests indicated that membrane rejected SMP, causing membrane pore blockage and then forming a gel layer. Batch adsorption experiments showed that adsorption of SMP onto PVDF membrane was a spontaneous physical adsorption process.Meanwhile, the absolute value ΔG of adsorption of SMP onto D3520 was higher than that of adsorption of SMP onto PVDF membrane, so SMP preferentially adsorbed onto D3520 rather than PVDF membrane. Thus, the effect of ARs on reducing the SMP concentration was investigated. It was found that, 6 g of D3520 was suitable for adsorption of SMP. This physical adsorption involved external film diffusion, intra-particle diffusion, and surface adsorption. The Redlich–Peterson isotherm model performed best in terms of describing this equilibrium data. The mechanism of membrane fouling mitigation was verified by MBR simulation system. A case study of AR–MBR system was conducted. The results showed that addition of D3520 can effectively alleviate the development of membrane fouling.     

Adsorption of butanol from aqueous solution onto a new type of macroporous adsorption resin: Studies of adsorption isotherms and kinetics simulation

BACKGROUND: Owing to the rapid depletion of petroleum fuel, the production of bio‐butanol has attracted much attention. However, low butanol productivity severely limits its potential industrial application. It is important to establish an approach for recovering low‐concentration butanol from fermentation broth. Experiments were conducted using batch adsorption mode under different conditions of initial butanol concentration and temperature. Batch adsorption data were fitted to Langmuir and Freundlich isotherms and the macropore diffusion, pseudo‐first‐ and second‐order models for kinetic study. RESULTS: The maximum adsorption capacity of butanol onto KA‐I resin increase with increasing temperature, ranged from 139.836 to 304.397 mg g^?1. The equilibrium adsorption data were well fitted by the Langmuir isotherm. The adsorption kinetics was more accurately represented by the macropore diffusion model, which also clearly predicted the intraparticle distribution of the concentration. The effective pore diffusivity (D_p) was dependent upon temperature, but independent of initial butanol concentration, and was 0.251 × 10^?10, 0.73 × 10^?10, 1.32 × 10^?10 and 4.31 × 10^?10 m² s^?1 at 283.13, 293.13, 303.13 and 310.13 K, respectively. CONCLUSION: This work demonstrates that KA‐I resin is an efficient adsorbent for the removal of butanol from aqueous solutions and available for practical applications for future in situ product recovery of butanol from ABE fermentation broth. Copyright © 2012 Society of Chemical Industry     

High efficient adsorption of gold ions onto the novel functional composite silica microspheres encapsulated by organophosphonated polystyrene

The novel functional composite silica microspheres encapsulated by organophosphonated polystyrene (SGPSNP) has been successfully synthesized. SGPSNP was employed to adsorb Au(III) from simulated wastewater, and it exhibited excellent performance, and the maximum adsorption capacity was 980.39 mg/g at 35 °C. The adsorption process optimization was performed using response surface methodology (RSM), and the analysis of variance (ANOVA) of the quadratic model demonstrated that the model was highly significant. Moreover, the regeneration capacities of SGPSNP were investigated, and it has been found that the adsorption capability remains high after several cycles of adsorption–desorption.     

Synthesis and thermal characterization of phenolic resin/silica nanocomposites prepared with high shear rate‐mixing technique

In this research the possibility to produce nanosilica/phenolic nanocomposites by means of a simple low labor cost mechanical approach was investigated. A commercial compatibilized nanosilica was selected as a filler and a resol diluted in methanol as a matrix. The morphology of the produced nanocomposites were studied by means of Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), whereas thermogravimetric analysis (TGA) was used to study the thermal stability of the nanocomposites. The post burning morphology of samples was also investigated. A rheological characterization was also carried out. The results of such study showed that it was possible to obtain a good degree of dispersion and distribution of the nanosilica particles, indicating that the proposed process could be successfully adopted as an alternative approach to sol‐gel techniques. Thermogravimetric analyses showed that all the produced nanocomposites exhibited a better thermal stability than the pristine matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fixed-bed column dynamic studies and breakthrough curve analysis of Eu(III) ion adsorption onto chemically modified SBA-15 silica materials

A continuous fixed bed study was carried out by using two SBA-15 mesoporous silica materials decorated with Schiff base ligands for the removal of Eu(III) from aqueous solutions. The impact of flow rates of the sample and eluent, column bed height, sample, and eluent volumes was investigated. The analysis of the breakthrough investigations showed the exhaustion time, exhaustion volume, and metal uptake capacities accrued with a decrease in the flow rate and with an increase in the bed height. Thomas and Yan models were fitted to the experimental data to work out the characteristic parameters of the column for process design.