Presence Of Silane Coupling Agent Research Articles

Mechanical, Thermal, Void Fraction and Water Absorption of Silane Surface Modified Silk Fiber Reinforced Epoxy Composites

ABSTRACT In this research, the silk fibers that were successfully extracted from silk cocoons using Na2CO3 were treated with silane coupling agent (3-aminopropyl)trimethoxysilane. The silane treated and untreated silk fiber reinforced epoxy composites were fabricated using the hand lay-up technique. The effects of fiber loading and the presence of silane coupling agent on the mechanical, morphological, thermal, void fraction, and water absorption properties of the silk fiber reinforced epoxy composites were studied. Fourier transform infrared (FTIR) analysis confirmed presence of silane group on the surface of fiber. The void fraction and water absorption increased with increasing fiber loading for both untreated and silane-treated composites. However, the silane-treated composites displayed lower increment of both void fraction and water absorption in comparison to the untreated samples suggesting better properties. The impact, flexural and tensile properties of the treated composites exhibited better property enhancement compared to the untreated samples with optimum fiber loading was observed at 30 wt%. The presence of this coupling agent also increased the thermal properties of the composites in general. The morphological studies revealed good interfacial compatibility between fiber and matrix in the presence of silane coupling agent which consistent with the enhancement observed for impact properties.

Glass lap joints with UV-cured adhesives: Use of a perfluoropolyether methacrylic resin in the presence of an acrylic silane coupling agent

In this work the adhesion to glass of a UV-curable resin with a high fluorine content, namely a methacrylic resin based on perfluoropolyether (PFPE) chains, was studied. In particular, focus was on how the presence of a silane coupling agent, with an acrylate functional group, used either for functionalizing the glass substrates or as an additive to the resin formulations, influenced such adhesion. The adhesive bond strength in shear of lap joints and their resistance to a humid environment and water were assessed. The silane was found to enhance the adhesive strength of the PFPE resin joints, and the silanization of glass proved to be more efficient than the addition of the additive into the formulations. The results were compared to those obtained with a fluorine free acrylic resin. Although the adhesion strength of the PFPE resin was lower compared to that of the fluorine free resin, it showed a better resistance to water as the hydrophobicity of the PFPE chains hindered the transport of water molecules at the resin/glass interface.

Effect and mechanism of calcium carbonate whisker on asphalt binder

Calcium carbonate whisker (CCW) has been widely used for its excellent mechanical and physical properties as well as low manufacturing cost and simple process. In this study, CCW was added into asphalt binder to produce modified asphalt. The morphological characteristics, thermal performance and rheological properties of CCW and the modified asphalts were studied with various experimental methods. In order to enhance the compatibility of asphalt and CCW, the silane coupling agent (2 wt%, KH-570) was used to treat the surface of CCW. Results show that the addition of CCW can improve the softening point of asphalt and decrease its penetration and ductility. In addition, the rutting resistance of the modified asphalt has been increased to some extent. As the presence of silane coupling agent, the interaction between asphalt and CCW and the storage stability of CCW modified asphalt were slightly increased.

Effects of the Particle Size of BaTiO₃ Fillers on Fabrication and Dielectric Properties of BaTiO₃/Polymer/Al Films for Capacitor Energy-Storage Application.

BaTiO3/polymer/Al (BPA) composite films for energy storage were fabricated by way of a roll coating and thermal curing process. The coating slurry consisted of silicon-containing heat-resistant resin (CYN-01) and BaTiO3 particles with various particle sizes obtained from commercial BaTiO3 powders processed at different durations of wet sand grinding in the presence of silane coupling agent (KH550), which not only improves the dielectric performance of the BPA films but also facilitates its production in a large scale. The major influence factors, such as the ratio between BaTiO3 and resin and the size of BaTiO3 particles, were investigated and their related mechanisms were discussed. The results show that modifying BaTiO3 particles (D90 = 0.83 μm) with the silane coupling agent of KH550 enhances the dielectric properties of the BPA films. The typical BPA films obtained exhibit a high dielectric constant of 32, a high break strength of 20.8 V/μm and a low dielectric loss of 0.014. The present work provides a simple and convenient way to prepare high-quality ceramic/polymer composite films for energy-storage application in a large scale.

A novel pathway for in situ synthesis of modified gelatin microspheres by silane coupling agents as a bioactive platform

ABSTRACTThis study investigated the fabrication and modification of gelatin microspheres via single emulsion method and silane coupling agents, respectively. Herein, the influence of oil phase and washing procedure on morphology and uniformity of microspheres was evaluated. The results of field emission scanning electron microscopy indicated a positive effect of olive oil on the production of uniform and approximately mono‐size spheres while monodispersity increased after samples were washed under ultrasonication. Investigation of crosslinking degree demonstrated that GPTMS could not show efficiency as high as glutaraldehyde, but the lack of toxicity and inducing bioactive behavior to the microspheres has made them appropriate for bone applications. Moreover, the stability of spheres after 14 days in phosphate buffered saline proved the ability of (3‐glycidyloxypropyl)trimethoxysilane to crosslink gelatin. The presence of silane coupling agents in prepared spheres caused the biomimetic formation of hydroxyapatite after a 14‐day immersion in simulated body fluid as observed by field emission scanning electron microscopy‐energy‐dispersive X‐ray spectroscopy, changes in pH, Fourier transform infrared spectroscopy, X‐ray diffraction, and atomic force microscopy. Adhesion, spreading, and proliferation of L929 cells on the hybrid microspheres corroborated the potential of gelatin spheres for biomedical application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46739.

Soil Burial Study of Palm Kernel Shell-Filled Natural Rubber Composites: The Effect of Filler Loading and Presence of Silane Coupling Agent

Palm kernel shell (PKS) was incorporated into natural rubber composites at loadings ranging from 0 to 20 phr using a laboratory-size two-roll mill. A soil burial study of the PKS-filled NR composites as a function of filler loading and silane coupling agent incorporation was then conducted over a period of six months. The degraded composites were evaluated by means of tensile testing. To study the degradation of the composites after soil burial, their morphological properties were observed by scanning electron microscopy. Prior to the soil burial tests, as the PKS filler loading increased, the tensile strength and elongation at break of the composites both with and without the silane coupling agent decreased, while the tensile moduli (M100 and M300) increased. At identical filler loading values, the NR/PKS composites with the incorporated silane coupling agent exhibited better tensile properties than the NR/PKS composites without the silane. Following the soil burial tests, the tensile strength, elongation at break, and the tensile moduli (M100 and M300) all decreased because of microbial attacks on the composites. The addition of silane enhanced the retention of the tensile properties of the NR/PKS composites after soil burial because of the improved adhesion at the filler-rubber matrix interface.

Development of HDPE‐modified eggshell composite

This paper investigates the effects of chemical modification of chicken eggshell powder (ESP) by silane coupling agent on the tensile, morphological, and thermal properties of high density polyethylene/chicken eggshell powder (HDPE/ESP) composites. The tensile and morphological properties of HDPE/ESP composites with and without chemical modifications have been characterized by a light weight tensile tester and scanning electron microscopy (SEM) under different ESP loading. The compounding of composites was done using Rheomix mixture to produce a homogenous mixture of ESP in HDPE. The processing torque is very dependent on the content of HDPE matrix resin. The thermal stability and thermal analysis of the composites were performed by thermogravimetric analysis and differential scanning calorimetric analysis (DSC). DSC result shows no significant differences on the melting and crystallization temperature of HDPE with and without chemical modification of ESP. Tensile strength and thermal stability of HDPE/ESP composites were improved with the modification of ESP by silane coupling agent. FTIR results show that ESP was successfully being modified and the silane coupling agent component is present in the composition. In the presence of silane coupling agent, the interfacial interaction and adhesion between HDPE and ESP were enhanced. POLYM. COMPOS., 39:1630–1637, 2018. © 2016 Society of Plastics Engineers

Influence of bis(triethoxysilylpropyl) tetrasulfide amount on the properties of silica-filled epoxidized natural rubber-based composites

AbstractThe aim of the present article is to investigate the influence of the amount of bis(triethoxysilylpropyl) tetrasulfide on the curing characteristics and mechanical and dynamic properties of rubber composites based on epoxidized natural rubber (Epoxyprene 50) filled with 70 phr silica. The obtained results showed that although the interaction between the epoxy groups of epoxidized natural rubber and the silanol groups of silica through hydrogen bonds improves the dispersion of filler in the rubber matrix, the presence of silane coupling agents is necessary to obtain rubber compounds and vulcanizates with good vulcanization characteristics and mechanical and dynamic properties.

Curing characteristics and mechanical properties of rattan‐powder‐filled natural rubber composites as a function of filler loading and silane coupling agent

AbstractCuring characteristics, tensile properties, morphological studies of tensile fractured surfaces using scanning electron microscopy (SEM), and the extent of rubber filler interactions of rattan‐powder‐filled natural rubber (NR) composites were investigated as a function of filler loading and silane coupling agent (CA). NR composites were prepared by the incorporation of rattan powder at filler loading range of 0–30 phr into a NR matrix with a laboratory size two roll mill. The results indicate that in the presence of silane CA, scorch time (ts2), and cure time (t90) of rattan‐powder‐filled NR composites were shorten, while, maximum torque (MH) increased compared with NR composites without silane CA. Tensile strength and tensile modulus of composites were enhanced whereas elongation at break reduced in the presence of silane CA mainly due to increase in rubber‐filler interaction. It is proven by SEM studies that the bonding between the filler and rubber matrix has improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Synthesis of high-performance green nanocomposites from renewable natural oils

This paper describes preparation and properties of green nanocomposites from renewable resources. The nanocomposites were synthesized by an acid-catalyzed curing of epoxidized natural oils in the presence of silane coupling agents. The resulting nanocomposites were transparent and highly glossy. Their hardness and Young's modulus of the nanocomposite coatings improved, as compared with those only from the epoxidized natural oils. Dynamic viscoelasticity analysis and TEM observation showed the homogeneous structure of the nanocomposites. The properties of the nanocomposites were strongly affected by the structure and feed ratio of the monomers.

Influence of selected alkoxysilanes on dispersive properties and surface chemistry of spherical silica precipitated in emulsion media

The process of silicas formation in emulsion system in the reaction of precipitation from water solutions of sodium silicate and hydrochloric acid has been studied. The effects of silica surface modifications with silane coupling agents from the group of alkoxysilanes with different functional groups have been determined. Both unmodified and modified silicas have been thoroughly characterised by scanning electron microscopy (SEM) and dynamic light scattering (DLS) and other methods. The effect of alkoxysilanes on the diameter distribution of the modified silica is insignificant; the presence of silane coupling agents causes a small increase in the particle diameter and a small increase in the tendency towards agglomeration, moreover the particles of silicon dioxide precipitated are characterised by spherical shape. The course of the electrokinetic curves depends mainly on the proton affinity of the modifiers. Significant changes in the stability of silica dispersions have been found as a result of modification with N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. This compound causes the greatest increase in the tendency towards agglomeration of the primary particles. The modification mechanism has been established to be chemisorption, as indicated by the 13C and 29Si CP MAS NMR spectra. The products have been shown to have typical mesoporous structure. The surface area of the unmodified silica is 133 m 2/g, while those for the modified silicas vary from 115 to 182 m 2/g.

Preparation, morphology, and adhesive and mechanical properties of ultrahigh‐molecular‐weight polyethylene/SiO2 nanocomposite fibers

AbstractA simple treatment approach has been performed to achieve enhanced surface properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers by incorporation of nano‐silicon dioxide (SiO2) in the presence of silane coupling agent during gel‐spinning process. The SiO2‐treated UHMWPE (UHMWPE/SiO2) nanocomposite fibers with different nano‐SiO2 compositions were characterized with Fourier transform infrared spectra, scanning electron microscopy, and wide‐angle X‐ray diffraction, and their interfacial adhesion and mechanical properties were also investigated. The nano‐SiO2 can be trapped on the surface of the fibers to form rough surface for UHMWPE/SiO2 fibers, and diffused into the inner of fibers to induce the lower crystal sizes and higher crystallinity of polyethylene in UHMWPE/SiO2 fibers. The resulting UHMWPE/SiO2 fibers therefore exhibit a dramatic enhancement in the adhesive properties because of the combination of rougher surface compared with those of UHMWPE fiber and polar groups absorbed on the surface of fibers. The mechanical properties of UHMWPE/SiO2 nanocomposite fibers are enhanced simultaneously because of the influence of nano‐SiO2 on the structure of UHMWPE crystalline regions and fibrils. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

Characterisation of the cross-linking process in an E-glass fibre/epoxy composite using evanescent wave spectroscopy

The term “self-sensing composites” is sometimes used to describe the case where the reinforcing glass fibres in advanced fibre-reinforced composites are used as the sensors for chemical process-monitoring (cure monitoring). This paper presents conclusive evidence to demonstrate that reinforcing E-glass fibres can be used for in situ cure monitoring. The cure behaviour of an epoxy/amine resin system was compared using evanescent wave spectroscopy via the reinforcing E-glass fibres and conventional transmission Fourier transform infrared spectroscopy. This paper also reports for the first time that evanescent wave spectroscopy via E-glass fibres can be used to detect the presence of silane coupling agents. Preliminary results indicated that the cure kinetics on the E-glass fibre surface, as observed using evanescent wave spectroscopy, were influenced by the silane coupling agent.

Roles of silane coupling agents on properties of silica-filled polychloroprene

Silane coupling agent is used extensively to improve reinforcing efficiency of silica. Recently, many types of silane coupling agents have been developed and their roles on reinforcing improvement have been studied in many types of rubbers. In the present study, roles of the two widely used silane coupling agents, i.e., bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) and 3-thiocyanatopropyl triethoxy silane (Si-264) were studied in silica-filled polychloroprene (CR). The results reveal that the presence of Si-69 and Si-264 improves significantly the processability of the rubber compounds. The improvement is more pronounced for Si-264 due to its lower molecular weight and, thus, viscosity. Surprisingly, the results show that Si-69 and Si-264 affect cure characteristics differently, i.e., Si-69 somewhat retards cure while Si-264 accelerates cure. However, both Si-69 and Si-264 result in an increased crosslink density of the vulcanizates. The presence of silane coupling agent also enhances the mechanical properties of the vulcanizates due to the combined effects of better filler dispersion, better rubber–filler interaction and increased crosslink density. A thorough look at the results also reveals that the property enhancement is obvious only at low silane loading (approximately 1.5 phr). Further increase of silane loading generally has little influence on properties of the vulcanizates. In the case of Si-264, excessive use of silane could impair certain properties such as modulus and hardness due to the plasticizing effect. Compared with Si-264, Si-69 imparts the rubber vulcanizates with poorer aging resistance. Explanation goes to the sulfur contribution effect of Si-69.

Comparison of reinforcing efficiency between Si-69 and Si-264 in an efficient vulcanization system

Silica is the main reinforcing filler for light colored products. Compared with carbon black, the use of silica experiences many problems, particularly poor rubber–filler interaction. In most cases, silane coupling agent is employed to overcome such problems. Since various types of silane coupling agent are now commercially available, the proper selection of silane coupling agent has become an important issue. In the present study, the reinforcing efficiency of bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) and 3-thiocyanatopropyl triethoxy silane (Si-264) was compared in an efficient vulcanization (EV) system. The results reveal that the addition of silane coupling agents greatly improves the compound processability. The improvement is more pronounced for Si-264. The presence of silane coupling agents also enhances slightly the mechanical properties due to the combined effects of better rubber–filler interaction and better filler dispersion. The optimum loadings of Si-264 and Si-69 are found to be 3.0 and 1.5 phr, respectively. Above such loadings, certain mechanical properties such as tensile and tear strengths are impaired, mainly due to the plasticizing effect for Si-264 and the sulfur contribution effect for Si-69. Compared with Si-264, Si-69 imparts the rubber vulcanizates with better dynamic properties but poorer aging resistance. Again, the explanation is given by the sulfur contribution effect of Si-69.

Effects of silane coupling agents on the vulcanization characteristics of natural rubber

AbstractThe vulcanization characteristics of silica‐filled natural rubber (NR) were studied in the presence of silane coupling agents, 3‐octanoylthio‐1‐propyltriethoxysilane (NXT) and bis [(3‐triethoxysilylpropyl) tetra sulfide] (TESPT, or Si‐69). The scorch time, cure rate index, and the rate constant of NR were measured using an Oscillating Disk Rheometer in the temperature range of 140–170°C. The scorch time of NR decreases with increasing TESPT and NXT concentrations, and the scorch time of NR compound with NXT is longer than that with TESPT. The apparent activation energies of vulcanization for the compounds with NXT and TESPT both decrease with increasing silane concentration. The apparent activation energy of vulcanization of NR compound with NXT is lower than that with TESPT at various concentrations. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1511–1518, 2004

Comparison of reinforcing efficiency between Si-69 and Si-264 in a conventional vulcanization system

Silica has long been recognized as a reinforcing filler, especially for light colored products. The degree of reinforcement is noticeably increased when silica is used in combination with silane coupling agent. Therefore, various types of silane coupling agents are now commercially available. In the present study, two types of silane coupling agents, e.g., bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) and 3-thiocyanatopropyl triethoxy silane (Si-264) were selected for comparison of their reinforcing efficiency in a conventional vulcanization (CV) system. The results reveal that the addition of silane coupling agent not only improves compound processability, but also enhances the mechanical properties of the rubber vulcanizates. Compared with Si-69, Si-264 gives rubber compounds with better processability due to its greater ability to promote filler dis-agglomeration during mixing. In addition, Si-264 also imparts a greater degree of reinforcement. This might be attributed to the combined effects of better rubber–filler interaction, better filler dispersion and higher state of cure which are obtained when Si-69 is replaced with Si-264. The dynamic properties of the rubber vulcanizates are also improved with the presence of silane coupling agent. In this aspect, Si-69 performs better than Si-264 as it provides rubber vulcanizates with lower heat build-up.

Effect of Silane Coupling Agent on Cure Characteristics and Mechanical Properties of Chloroprene Rubber/Reclaimed Rubber Blend

Chloroprene rubber was blended with whole tire reclaimed rubber (WTR) in presence of different levels of a coupling agent Si69 [bis-(3-(triethoxysilyl)propyl)tetrasulfide] and the cure characteristics and mechanical properties were studied. The rate and state of cure were also affected by the coupling agent. While the cure time was increased, the cure rate and scorch time were decreased with increasing silane content. Tensile strength, tear strength, and abrasion resistance were improved in the presence of coupling agent. Compression set and resilience were adversely affected in presence of silane-coupling agent. Aging studies showed that the blends containing the coupling agent were inferior to the unmodified blends.

Effect of curing system on reinforcing efficiency of silane coupling agent

Silane coupling agent has long been used to enhance degree of reinforcement of silica. The mechanical properties of silica-filled vulcanizates are greatly improved in the presence of silane coupling agent, mainly due to an increase in rubber–filler interaction. Recently, various types of silane coupling agent have been developed and commercialized. In the present study, two types of silane coupling agent, i.e. bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) and 3-thiocyanatopropyl triethoxy silane (Si-264) were selected for comparison of their reinforcing action in various curing systems: conventional vulcanization (CV), semi-efficient vulcanization (semi-EV) and efficient vulcanization (EV). The results reveal that the addition of silane coupling agents not only improves compound processability, but also enhances the mechanical properties of the rubber vulcanizates. The effect of silane type on processability is found to be independent of the curing system. Compared with Si-69, Si-264 can react with the silanol groups on the silica surface more readily, due to its less bulky structure and lower viscosity. In other words, Si-264 can reduce the filler–filler interaction to a greater extent than Si-69, leading to better compound processability. The effect of silane type on the vulcanizate properties, on the other hand, depends greatly on the curing system. For CV and semi-EV systems, Si-264 imparts greater degree of reinforcement than Si-69. This might be attributed to the combined effects of better rubber–filler interaction, better filler dispersion and higher state of cure when Si-69 is replaced with Si-264. However, for the EV system, contrary results are obtained, i.e. Si-69 provides better reinforcement than Si-264. Explanation is given to the effect of sulfur contribution of Si-69 which is dominant only in the EV system.

Melt blending of poly(ethylene terephthalate) with polypropylene in the presence of silane coupling agent

AbstractA silane coupling agent (SCA) was used as a compatibilizer for polypropylene–poly(ethylene teraphthalate) (PP–PET) blends with 20, 40, 50, and 60% PET compositions by weight. PP–PET mixtures were blended with and without an SCA by a single‐screw extruder. The effect of silane modification on the tensile and impact properties of the blends was investigated. The morphology and thermal behavior of the blends were examined with scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The presence of the SCA used in this work extensively improved the mechanical properties of the blends. Mechanical properties were found to be highly dependent on the numbers of extrusions. SEM studies showed that substantially different morphology with better adhesion existed when SCA‐treated blends were compared to nontreated PP–PET blends. The presence of individual melting temperatures of the polymers in all compositions with no significant Tm depression indicated that PET and PP were crystallized separately. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1039–1048, 2003