MEK wiping prior to chlorination to improve the adhesion of vulcanized SBR rubber containing paraffin wax

In this study, it was shown that the degree of effectiveness produced by halogenation with trichloroisocyanuric acid (TCI) was influenced by previous methyl ethyl ketone (MEK) wiping of a synthetic vulcanized styrene-butadiene rubber (R2) surface. The MEK wiping of the R2 rubber surface prior to chlorination with TCI removed the paraffin wax layer from the surface, which favoured the chlorination and oxidation reactions of the rubber. Chlorination with TCI decreased the contact angle values (increased the wettability) mainly due to the creation of C–Cl and C=O moieties, as well as roughness. The amount of these chemical moieties increased when the MEK wiping was applied prior to chlorination, so higher degrees of chlorination and oxidation were obtained on the R2 rubber surface. T-peel strength values increased more markedly if the MEK wiping was carried out before chlorination with TCI, in agreement with the higher degree of modifications produced in the R2 rubber surface. In fact, a cohesive failure in the R2 rubber was obtained in the adhesive joint produced with MEK wiped + TCI chlorinated R2 rubber.     

UV treatment of synthetic styrene-butadiene-styrene rubber

The effectiveness of the treatment with ultraviolet light (UV) on several polymeric surfaces has previously been established. In this study, a low pressure mercury vapour lamp was used as a source of UV radiation for the surface treatment of a difficult-to-bond block styrenebutadiene-styrene rubber (S6), the treatment time ranging from 10 s to 30 min. The UV-treated S6 rubber surfaces were characterized by contact angle measurements (ethylene glycol, 25°C), ATR-IR spectroscopy, XPS, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). T-peel tests on UV-treated S6 rubber/polyurethane (PU) adhesive/ leather joints (before and after ageing) were carried out to quantify adhesion strengths. The UV treatment of S6 rubber produced improved wettability, the formation of C—O, C=O and COO^- moieties, and ablation (removal of a thin rubber layer from the surface). The extent of these modifications increased with increasing treatment time. The extended UV treatment produced greater surface modifications, as well as the incorporation of nitrogen moieties at the surface. Furthermore, noticeable ablation of S6 rubber surface occurred. Peel strength values increased with increased treatment time of UV treatment of S6 rubber. Also, with increasing treatment time, the adhesive joints showed different loci of failure: adhesional failure for the as-received and 2 min-UV treated S6 rubber/polyurethane adhesive/leather joints changed to mixed failure (cohesive in the treated S6 rubber + adhesional failure) for the 30 min-UV treated S6 rubber/polyurethane adhesive/leather joint.     

SURFACE MODIFICATIONS AND ADHESION OF VULCANIZED SBR RUBBER TREATED WITH RF PLASMAS OF DIFFERENT GASES

The surface modifications produced by treatment of a synthetic vulcanized styrene-butadiene rubber (R1) with oxidizing (oxygen, air, carbon dioxide) and nonoxidizing (nitrogen, argon) RF plasmas have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the treatment depended on the gas atmosphere used to generate the RF plasma. In general, acceptable adhesion values of treated R1 rubber were obtained for all plasmas, except for the nitrogen plasma treatment during 15?min, due to the creation of weak layers of low molecular weight moieties on the outermost R1 rubber layer. A toluene wiping of the 15?min N₂-plasma–treated R1 rubber surface removed those moieties, and increased adhesion was obtained. On the other hand, the air, carbon dioxide, and oxygen plasmas produced ablation of the R1 rubber surface, whereas mechanical degradation was not produced by treatment with the Ar plasma.     

SURFACE MODIFICATIONS AND ADHESION OF VULCANIZED SBR RUBBER TREATED WITH RF PLASMAS OF DIFFERENT GASES

The surface modifications produced by treatment of a synthetic vulcanized styrene-butadiene rubber (R1) with oxidizing (oxygen, air, carbon dioxide) and nonoxidizing (nitrogen, argon) RF plasmas have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the treatment depended on the gas atmosphere used to generate the RF plasma. In general, acceptable adhesion values of treated R1 rubber were obtained for all plasmas, except for the nitrogen plasma treatment during 15 min, due to the creation of weak layers of low molecular weight moieties on the outermost R1 rubber layer. A toluene wiping of the 15 min N₂-plasma-treated R1 rubber surface removed those moieties, and increased adhesion was obtained. On the other hand, the air, carbon dioxide, and oxygen plasmas produced ablation of the R1 rubber surface, whereas mechanical degradation was not produced by treatment with the Ar plasma.     

Surface Characterization of Vulcanized Rubber Treated with Sulfuric Acid and its Adhesion to Polyurethane Adhesive

Modifications produced on a vulcanized styrene -butadiene rubber surface by treatment with sulfuric acid were studied and several experimental variables were considered.

The treatment of R1 rubber with sulfuric acid produced a noticeable decrease in contact angle which was mainly ascribed to an increase in surface energy due to the formation of sulfonic acid moieties and C=O bonds, and the removal of zinc stearate. The rubber surface swelled and became brittle as a result of the treatment, and when flexed microcracks were created. A rubber surface layer modification was produced with a consequent decrease in tensile strength and elongation-at-break values. The treatment enhanced the T-peel strength of R1 rubber/polyurethane adhesive joints and the locus of failure was cohesive in the rubber.

The optimum immersion time in H₂SO₄ solution was less than 1 min., and the reaction time in air was not found to be critical; the neutralization with ammonium hydroxide and the high concentration of the sulfuric acid (95 wt%) were essential to produce adequate effectiveness of the treatment.     

Surface Characterization of Vulcanized Rubber Treated with Sulfuric Acid and its Adhesion to Polyurethane Adhesive

Modifications produced on a vulcanized styrene –butadiene rubber surface by treatment with sulfuric acid were studied and several experimental variables were considered.

The treatment of R1 rubber with sulfuric acid produced a noticeable decrease in contact angle which was mainly ascribed to an increase in surface energy due to the formation of sulfonic acid moieties and C?O bonds, and the removal of zinc stearate. The rubber surface swelled and became brittle as a result of the treatment, and when flexed microcracks were created. A rubber surface layer modification was produced with a consequent decrease in tensile strength and elongation-at-break values. The treatment enhanced the T-peel strength of R1 rubber/polyurethane adhesive joints and the locus of failure was cohesive in the rubber.

The optimum immersion time in H₂SO₄ solution was less than 1 min., and the reaction time in air was not found to be critical; the neutralization with ammonium hydroxide and the high concentration of the sulfuric acid (95 wt%) were essential to produce adequate effectiveness of the treatment.     

硫酸处理对天然橡胶界面粘结性能的影响

采用硫酸溶液处理天然橡胶表面以改善其粘结性能。通过力学性能测试、电子扫描电镜（SEM）、能量分析光谱（EDX）、接触角分析等研究了不同处理时间对天然橡胶表面粘结性能的影响。随着处理时间的延长,天然橡胶表面的接触角先减小后增大;SEM测试结果表明经过硫酸处理后天然橡胶表面的粗糙度和微裂纹增多,有利于胶粘剂的润湿和渗透;EDX测试结果显示,橡胶表面氧元素含量增多,表明引入了含氧极性基团—C O、—COO-等。随着处理时间的延长,T-型剥离强度先增大后减小,用质量分数为80%的H2SO4溶液处理15 min时,剥离强度达到最大值10.67 kN/m。硫酸处理可改善天然橡胶表面的表面形貌、化学性质及其润湿性,有利于粘结强度的提高,从而提高天然橡胶的粘结性能。     

Surface Characterization of Chlorinated Synthetic Vulcanized Styrene-Butadiene Rubber Using Contact Angle Measurements,Infra-Red Spectroscopy and XPS

The surface of a sulfur-vulcanized synthetic styrene-butadiene rubber (SBR) was treated with ethyl acetate solutions containing different amounts of trichloroisocyanuric acid (TCI). The chlorinated SBR surfaces were characterized using contact angle measurements (water, ethane diol, n-hexadecane), infra-red (IR) spectroscopy and XPS. Chlorination produced an increase of surface free energy which was mainly due to the enhancement of the acid-base component of the surface free energy, which remained almost unchanged when the amount of TCI was increased. Depending on the amount of chlorination agent, several chemical species were present on the SBR surface: i) For low amounts of TCI (up to 2 wt%), mainly chlorinated hydrocarbon and C – O species were present on the surface; ii) For medium amounts of TCI (between 2 and 5 wt%), an excess of unreacted TCI remained on the surface and a relatively small amount of isocyanuric acid was deposited; iii) For high amounts of TCI (larger than 5 wt%), a weak boundary layer (mainly composed of isocyanuric acid) was formed on the surface and thus the effects due to chlorination were decreased. There was good agreement between the experimental results obtained with contact angle measurements and XPS because both provided information on a surface region close to 100 Å, whereas IR spectroscopy results showed deeper penetration of the chlorinating agent into the SBR surface. The estimated thickness of the chlorinated layer was near 5000 Å as estimated from XPS measurements of SBR surfaces modified by argon ion bombardment.     

Improved adhesion of poly(tetrafluoroethylene) by NH3-plasma treatment

—Surface modification of poly(tetrafluor oethylene) (PTFE) by NH₃-plasma treatment was investigated by means of contact angle measurement, XPS, and ATR FT/IR spectroscopy. The modified surfaces were adhesively bonded to nitril rubber. The NH₃-plasma irradiation made PTFE surfaces hydrophilic. The contact angle of water on the modified PTFE surface was 16 deg, and the surface energy was 62-63 mJ/m². The NH₃-plasma irradiation improved adhesion between PTFE and nitril rubber using a phenol-type adhesive. The peel strength of the joints reached 8.1 × 10³ N/m. Carbonyl and amido groups were created on PTFE surfaces by the NH₃-plasma irradiation. The mechanism of the improvement of adhesion by the NH₃-plasma irradiation is discussed.     

酸处理法降低橡胶材料摩擦系数的研究

进行了硫酸溶液对天然橡胶型汽车刮水板橡胶的表面处理研究,讨论了酸含量,处理时间等因素对刮水板橡胶的摩擦系数,力学性能及表面状况的影响,结果表明,选择适当的酸含理和酸处理时间可获得较好的处理效果,使摩擦系数降低到0．1以下。     

Reinforced chloroprene rubber by in situ generated silica particles: Evidence of bound rubber on the silica surface

Nano silica is generated in situ inside the uncrosslinked chloroprene rubber (CR) by the sol‐gel reaction of tetraethoxysilane (TEOS). This results in appreciable improvement in mechanical properties of the CR composites at relatively low filler content. Furthermore, exploitation of reactive organosilanes, γ‐aminopropyltrimethoxysilane (γ‐APS) in particular, in the silica synthesis process facilitates growing of spherical silica particles with a size distribution in the range of 20‐50 nm. The silica particles are found to be uniformly dispersed and they do not suffer from filler‐filler interaction. Additionally, it is observed that the silica particles are coated by silane and rubber chains together which are popularly known as bound rubber. The existence of the bound rubber on silica surface has been supported by the detailed investigations with transmission electron microscopy (TEM), energy filtered transmission electron microscopy (EFTEM) and energy dispersive X‐ray spectroscopy (EDAX). The interaction between rubber and silica, via bi‐functionality of the γ‐APS, has been explored by detailed FTIR studies. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43717.     

超细碳酸钙表面处理及其在RTV硅橡胶中的应用(一)

采用自制的超细碳酸钙悬浊液,在碳酸钙表面包覆二氧化硅,改善碳酸钙的应用性。采用吸油值、耐酸性、沉降体积等测试方法衡量二氧化硅的包覆效果。实验结果表明能够在碳酸钙表面形成较为紧密的二氧化硅膜。     

Evaluation of effects of non-thermal plasma treatment on surface properties of CAD/CAM materials

The purpose of this in vitro study was to evaluate the effect of the non-thermal plasma (NTP) treatment on the wettability and surface roughness of different types of CAD/CAM materials as well as the shear bond strength (SBS) of adhesive resin cement to the treated surfaces. Three different materials, namely; resin nano ceramic, feldspathic ceramic and poly(methyl methacrylate) (PMMA)-based samples were treated with NTP for different time points to evaluate the effect of NTP treatment on the surface properties of CAD/CAM materials. Moreover, surfaces of CAD/CAM materials were visualised with scanning electron microscopy (SEM). A 90-second NTP treatment time was determined as the optimum time for the highest measured wettability, and thus, the 90-second NTP treated samples were used for the SBS test and evaluation of the failure types. Our results revealed the NTP treatment lowered the contact angles and increased the roughness of all tested materials. Moreover, The NTP treatment significantly enhanced the SBS of resin nano ceramic and feldspathic ceramic-based materials. NTP could be considered as a novel pre-treatment method to improve surface properties and the bonding performance of ceramic-based CAD/CAM materials.     

Influence of calcium carbonate added to the SBS rubber formulation on the surface modifications produced by halogenation

To improve the adhesion properties of styrene–butadiene–styrene (SBS) rubber sole to polyurethane adhesive, surface treatments are required, of which halogenation with trichloroisocyanuric acid (TCI) solutions in organic solvents is the most commonly used treatment in the footwear industry. Calcium carbonate filler is commonly added to improve the mechanical properties and to reduce shining of SBS rubber formulations. The influence of the filler on the effectiveness of surface chlorination of SBS rubber had not been considered in the existing literature. Therefore, 10 wt% calcium carbonate filler was added to the SBS rubber formulation and the surface modifications and adhesion properties produced by treatment with TCI solutions were investigated. The resulting surface modifications and adhesion were compared to those obtained in unfilled SBS rubber. It is shown that the treatment with TCI solutions was less effective in the calcium-carbonate-filled SBS rubber and a lower peel strength to polyurethane adhesive was obtained; however, a cohesive failure in the rubber was always obtained.     

The effects of Al surface treatment,adhesive thickness and microcapsule inclusion on the shear strength of bonded joints

The influences of various Al surface treatments, adhesive thicknesses as well as the incorporation of synthesized microcapsules into epoxy adhesive on the shear strength of adhesive/ Al joints have been investigated using lap-shear tensile tests. First, the influence of adhesive thickness on the shear strength of joints has been presented. Then, the effects of various Al surface treatments on the surface roughness of Al and shear strength of joint have been researched. Atomic force microscopy was used to study the Al surface morphologies and textures. Finally the few micron-sized polymeric microcapsules were synthesized and the shear performances of microcapsule filled epoxy adhesives were inspected. It was observed that the HCl acid based etching increased both micro-roughness and nano-texture of the Al surface and led to the peak shear strength. Moreover, HCl-nitric acid treatment offered the maximum value for the cohesive failure. Capsule inclusions into the adhesive displayed different influences on the joint shear performances depending on the capsule morphology and the surface treatment of Al.     

Filler-elastomer interactions: influence of oxygen plasma treatment on surface and mechanical properties of carbon black/rubber composites

In this work, the influence of oxygen plasma treatment on the surface and adsorption properties of carbon blacks was investigated using X-ray photoelectron spectroscopy (XPS), ζ-potential, and BET isotherms. Then the mechanical properties [tensile strength and tearing energy (G_IIIC)] of carbon black/acrylonitrile butadiene rubber (NBR) composites were measured. As a result, it was found that oxygen plasma treatment generated oxygen-containing functional groups, such as, carboxyl, hydroxyl, lactone, and carbonyl groups, on the carbon black surfaces, resulting in a decrease in the equilibrium spreading pressure or London dispersive component of surface free energy. The tearing energy of the carbon black/NBR composites improved as the oxygen-containing functional groups on the carbon black surfaces increased. This revealed that there is a relatively high degree of interaction between the polar NBR and the oxygen-functional groups of carbon blacks.     

酸碱不同电解质对碳纤维阳极氧化表面处理的研究

以碳酸氢铵和硫酸为电解质,采用阳极氧化表面处理法对聚丙烯腈(PAN)基碳纤维进行表面处理,对表面处理时间进行了对比研究,获取了S-酸和S-碱2个系列样品,经研究发现,碳纤维在碳酸氢铵电解质中处理时间80s时,同在硫酸电解质中处理时间为5s所取得到的拉伸强度、层间剪切强度基本相当。通过对样品的微观表面、表面官能团的分析,发现2种电解质在PAN基碳纤维表面发生的氧化反应不同,S-酸系列样品表面官能团多生成羟基和醚基,S-碱系列样品表面团多生成羰基。     

Plasma treatment effect on the surface energy of carbon and carbon fibers

The surface energy dispersive (γ^D_S) and polar (γ^P_S) components of carbon model surfaces (bal planes, prismatic surfaces, vitreous carbon) and of carbon fibers (high strength and high modulus, respectively) were determined systematically before and after plasma treatment. The method used is essentially based on the wetting contact angle measurements within two liquids. In all cases (γ^P_S) is markedly increased by the plasma treatment. For carbon fibers, with increasing plasma treatment duration (γ^P_S) is increasing toward a limiting value (-30 mJ/m²) while (γ^D_S) is depressed toward low values (-10 mJ/m²). The parallel evolution of surface topography is followed by SEM observations. The changes in surface energy of carbon model surfaces is also discussed.     

Influence of silicoating,etching and heated glaze treatment on the surface of Y-TZP and its impact on bonding with veneering ceramic

The study aimed to investigate the influence of surface treatments of Y-TZP on its topography and their impact on shear bond strength (SBS) of Y-TZP to veneering porcelain. Thirty-four zirconia cubes (Cercon) (10 × 10 × 10 mm³) were divided randomly into 3 groups (n = 11) according to the different surface treatments, Silica Coating (SC); Hot Solution Etching (HE); and Heat Treatment after porcelain glaze and powder application (GP). Porcelain application (IPs e.max) was performed after surface treatment using a standardized technique. Porcelain application (Ceramco-3) was also performed on 10 metal cubes (I BOND 2) as controls (MC). Specimens were subjected to thermocycling (5–55 °C, 20,000 cycles) followed by SBS testing in a universal testing machine. Surface topography was assessed by scanning electron microscopy and surface roughness (Image J). SC developed significantly higher SBS (42.10 ± 5.84 MPa) of Y-TZP to veneering ceramics compared to treatment by HE (24.0 ± 6.4 MPa), GP (23.30 ± 4.72), and the MC (29.3 ± 5.4 MPa) control (p < 0.05). SBS among HE, GP and MC specimens was comparable (p > 0.05). Y-TZP specimens treated with SC and HE showed high surface roughness compared to GP. Silicoating of Y-TZP prior to veneering can potentially reduce the high failure rates of zirconia-based restorations by enhancing the chemical bond between the core and the veneer materials.     

Effect of DC glow discharge treatment on the surface energy and surface resistivity of thin film of polypropylene

A change in the surface energy and surface resistivity of a thin film of polypropylene (PP) of thickness 100 μm was investigated, using direct current (DC) glow discharge. The thin film of the PP was treated for various discharge powers and treatment time and the modification in the surface energy and the surface resistivity was observed. To investigate the modification in the surface energy after DC glow discharge treatment, contact angle of two test liquids formamide and de‐ionized water over the surface of PP film was measured. By measuring the contact angle the change in surface energy and its two polar and dispersive components have been measured. It was observed that at a given power level of DC glow discharge surface energy and its polar component increases with increase of the treatment time, attains a maximum value, and then becomes almost constant. Correspondingly, with increase in surface energy, a decrease in surface resistivity was observed. Also, a change in surface morphology was observed by atomic force microscopy and by FT‐IR spectra generation of polar groups at the surface of PP film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 767–772, 2007