Surface Coupling Agent Research Articles

The Role of Surface Treatment and Coupling Agents for Adhesion between Stainless Steel (SUS) and Polyamide (PA) of Heterojunction Bilayer Composites.

The growing demand for lightweight and durable materials in industries, such as the automotive, aerospace, and electronics industries, has spurred the development of heterojunction bilayer composites, combining the structural integrity of metals with the versatility of polymers. This study addresses the critical interface between stainless steel (SUS) and polyamide 66 (PA66), focusing on the pivotal role of surface treatments and various silane coupling agents in enhancing the adhesion strength of heterojunction SUS/PA66 bilayer composites. Through systematic surface modifications-highlighted by scanning electron microscopy, atomic force microscopy, and contact angle analyses-the study assessed the impact of increasing the surface area, roughness, and energy of SUS. X-ray photoelectron spectroscopy evaluations confirmed the strategic selection of specific silane coupling agents. Although some coupling agents barely influenced the mechanics, notably, aminopropyl triethoxysilane (A1S) and 3-glycidyl oxypropyl trimethoxysilane (ES) significantly enhanced the mechanical properties of the heterojunction bilayer composites, evidenced by the improved lap shear strength, elongation at break, and toughness. These advancements were attributed to the interfacial interactions at the metal-polymer interface. This research underscored the significance of targeted surface treatment and the judicious selection of coupling agents in optimizing the interfacial adhesion and overall performance of metal-polymer composites, offering valuable insights for the fabrication of materials where reduced weight and enhanced durability are paramount.

3D Printing of Low-Filled Basalt PA12 and PP Filaments for Automotive Components

Fused Deposition Modeling (FDM) enables many advantages compared to traditional manufacturing techniques, but the lower mechanical performance due to the higher porosity still hinders its industrial spread in key sectors like the automotive industry. PP and PA12 filaments filled with low amounts of basalt fibers were produced in the present work to improve the poor mechanical properties inherited from the additive manufacturing technique. For both matrices, the introduction of 5 wt.% of basalt fibers allows us to achieve stiffness values comparable to injection molding ones without modifying the final weight of the manufactured components. The increased filament density compared with the neat polymers, upon the introduction of basalt fibers, is counterbalanced by the intrinsic porosity of the manufacturing technique. In particular, the final components are characterized by a 0.88 g/cm3 density for PP and 1.01 g/cm3 for PA12 basalt-filled composites, which are comparable to the 0.91 g/cm3 and 1.01 g/cm3, respectively, of the related neat matrix used in injection molding. Some efforts are still needed to fill the gap of 15–28% for PP and of 26.5% for PA12 in tensile strength compared to injection-molded counterparts, but the improvement of the fiber/matrix interface by fiber surface modification or coupling agent employment could be a feasible solution.

Influence mechanism of organic-modified α-zirconium phosphate on tribological properties of UHMWPE

Ultra-high molecular weight polyethylene (UHMWPE) is prone to deformation and wear under harsh conditions of dry friction with high contact stress, and failing friction parts. In this work, CZrP/UHMWPE composites with different organic-modified α-zirconium phosphate (CZrP) contents were prepared. The tribological properties of the GCr15/composites friction pair under dry friction conditions were studied by ball-on-disk tribology experiments, and the wear mechanism was analyzed. The results show that when the content of CZrP is 5 wt%, the friction coefficient and wear loss of CZrP/UHMWPE composites are the smallest, which are about 30% and 58% lower than those of pure UHMWPE. In the process of dry sliding friction and wear, CZrP will gradually accumulate on the friction surface of the composite material, and a protective layer with certain strength and lubricity will be formed through the unique interlayer sliding effect of CZrP. The hydrogen bonding between the molecular chains of the surface coupling agent and the physical entanglement with the molecular chains of UHMWPE make the accumulated CZrP not easy to be worn and peeled off. This work aims to provide an effective strategy to improve the tribological properties of UHMWPE under severe conditions with high contact stress.

A critical review on mechanical and morphological characteristics of injection molded biodegradable composites

AbstractFactors like environmental and societal awareness often lead to a significant change of action in the development of eco‐friendly materials like the family of green composites. Green composites are becoming increasingly apparent as a sensible and potentially viable alternative to the synthetic composites. A healthy synergism of factors to include weight reduction, cost, performance improvement, biodegradable nature, nontoxic properties, and flexibility are often the key motives that provide the much needed impetus for the development of green composites for the purpose of selection and use in a spectrum of applications. The biodegradable or green composites became a viable substitute for the long‐established materials and often a challenge to the family of synthetic polymer‐based composites. The present study draws attention to the issues and challenges that come in the way of development and characterization of “green” composites primarily on the use of advanced manufacturing processes like injection molding. In this article, the chemical composition, structure, mechanical properties, and classification of the natural fibers are presented and briefly discussed. The mechanical properties, to include tensile response, flexural behavior, and impact strength, of the injection molded composites are presented and adequately discussed. The effect and role of surface treatments and coupling agents on mechanical properties of the family of polymer composites, to include the nonbiodegradable composites, partially green composites, and fully green composites, are examined and adequately discussed.

Coining the attributes of nano to micro dual hybrid silica-ceramic waste filler based green HNBR composites for triple percolation: Mechanical properties, thermal, and electrical conductivity

Industrial waste management and pollution control are the prime concerns today. Ceramic materials are widely used in various industries and applications; therefore, waste generation is enormous. Thus, in this work, we intend to develop silica-ceramic waste-based nano to micro-hybrid filler sustainable composites based on the percolation optimization of mechanical, thermal, and electrical properties. The developed composites exhibited improved mechanical properties and enhanced thermal conductivity (0.8 W/mK) without any surface modification. The reported value of thermal conductivity is almost double with respect to conventional carbon black filled samples (0.43 W/mK). The addition of such hybrid fillers helped in the in-situ modification of the filler network by infringement of the silica network. The composites retained their basic technical properties (tensile strength and elongation at break) even with higher loading of ceramic waste fillers. The system displayed enhanced dispersion due to the incorporation of such exclusive dual hybrid fillers. Such high loading of ceramic fillers without surface treatment or coupling agent is the first of its kind to be reported. The development of the thermal conductivity of the composites was also cross-validated using mathematical models. These composites also possess electrical conductivity in the insulative to semi-conductive domain range. These fillers can find their potential application in new-generation green and environment-friendly fillers to replace carbon black without hampering basic technical properties by reducing the carbon footprints. Due to such a combination of mechanical, electrical, and thermal attributes, these composites can find budding applications in printed circuit boards, mounts, isolators, and other e-automotive applications.

The effect of fibre surface treatment and coupling agents to improve the performance of natural fibres in PLA composites

Abstract This paper describes work carried out to assess the effect of fibre treatments and coupling agent on the mechanical performance of PLA composites reinforced with 20 wt% fibre. The chemically-treated harakeke and hemp fibres used to produce fibre mats. Maleic anhydride (MA) grafted PLA (MA-g-PLA) was used as a coupling agent. Composites with fibre treated with silane and dicumyl peroxide (DCP) and composites using MA-g-PLA were characterised by swelling testing, scanning electron microscopy (SEM), tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It was found that the interfacial bonding for composites with fibres treated using silane and peroxide and composites coupled with MA-g-PLA noticeably improved supported by lower swelling indices, higher tensile strengths and lower tan δ compared to those composites with fibres treated using alkali only, with the highest tensile strength of about 11% higher obtained from composites treated with MA-g-PLA followed by silane and then peroxide. However, using silane, peroxide and MA-g-PLA as additional composite treatments increased significantly the composite failure strain by up 11, 19 and 30%, respectively for harakeke composites and by 13, 24 and 30%, respectively for hemp composites.

Modification of CaCO3 and CaCO3 pin-coated cellulose paper under supercritical carbon dioxide-ethanol mixture for enhanced NO2 capture.

In this work, we examine two modifications of fine-ground calcium carbonate material (GCC) in order to enhanced sorption of NO2 and subsequent reaction properties toward NO2-/NO3- formation by firstly exposing the GCC to supercritical (sc) CO2 in order to increase particle surface area, a choice specifically made to avoid altering the surface chemistry, and secondly considering the potential advantage of using a surface coupling agent toward NO2. The modification by the coupling agent amino silane (AMEO silane) was applied in a supercritical CO2-ethanol mixture. The samples were characterised before and after modification by field emission scanning electron microscopy (FESEM), specific surface area determination (BET nitrogen adsorption), ATR-FTIR spectroscopy and ion chromatography to reveal the effects of the surface modification(s) on the morphology, surface textural properties and sorption versus reaction properties with NO2. The performance of the treated sorbents for NO2 capture was evaluated at room temperature. Results show that reactivity of NO2 with GCC was observed to increase as a function of increased surface area resulting from scCO2 exposure, but that the presence of AMEO silane on the surface, while enhancing initial adsorption of NO2 was seen subsequently to act to block reactivity. Thus, judicious use of coupling agent can provide desired rapid initial adsorption of the gas, but the goal of long-term CaCO3-consuming reactivity, so as to prolong the uptake of NO2 beyond surface saturation alone, is achieved by increasing surface area while retaining chemical-free exposed CaCO3 surface.

Roles of the Coupling Agent and Surfactant in Droplet Structure in Sizing Emulsions: A Molecular Dynamics Simulations Study

Sizing emulsions used as glass fiber surface treatments in composites manufacturing are aqueous suspensions of hydrophobic film formers, surface coupling agents, and surfactants. We employ all-atom molecular dynamics simulations to characterize droplet structures in several aqueous blends of the film-former diglycidyl ether of bisphenol A, coupling agent glycidoxypropyl trimethoxysilane, and a triblock copolymer surfactant (Pluronic L35 PEO/PPO copolymer). We show that the quasi-equilibrium states of emulsion droplets are invariant to different initial configurations. We examine the role of the surfactant in determining coupling agent partitioning between the droplet shell and corona and coupling agent cluster size distributions. This work takes a step toward systematic understanding of the sizing chemistry to optimize the interface between the glass and the resin in commercially relevant composites.

Influence of surface treatments and coupling agents on the thermal and thermo‐mechanical properties of yerba mate/post‐consumer polypropylene composites

AbstractThe main objective of this work is to evaluate an interaction between yerba mate fibers (YM) and post‐consumption polypropylene (r‐PP) using the surface treatments and coupling agent. YM fibers were submitted to two different surface treatments: alkaline solution (NaOH 10%) and 3‐aminopropyltriethoxysilane (APTS) (5 wt%). The influence of 5 wt% addition of maleic anhydride (MA)‐grafted polypropylene copolymer (PP‐g‐MA) coupling agent in the composite processing was also evaluated. YM of 30 wt% was loaded into r‐PP by extrusion, and then the specimens were prepared by injection molding. The results showed that all treatments were effective in improving thermal stability increase the maximum degradation temperature by approximately 5°C, as also confirmed by differential scanning calorimetry analysis. Composite with PP‐g‐MA presented the greater increase in thermal stability and in the crystallization index (approximately 46% in relation to the r‐PP/YM30 composite). DMA analysis revealed increases in the storage and loss moduli and a decrease in the damping factor for all composites produced with treated fibers and coupling agent. The enhancement of the analyzed properties of these composites is related to the better interfacial adhesion between YM fiber and r‐PP, which was confirmed by scanning electron microscope micrographs.

Effect of surface coupling agents on the mechanical behaviour of polypropylene/silica composites: a molecular dynamics study

We investigate the mechanical behavior of polypropylene/silica composites under mode I and II loading by using molecular dynamics simulations, focusing on the effects of two typical surface coupling agents of HMDZ and APTES on the interface deformation and failure. It is found that under mode I loading, the silica surface functionalized with APTES can enhance the tensile strength of polypropylene/silica composites effectively. In contrast, the silica surface functionalized with HMDZ has little effect on the tensile strength. The simulation results are supported by experiments. Under mode II loading, it is found that both HMDZ and APTES can enhance the shear strength of polypropylene/silica composites with APTES being more effective. The underlying mechanisms for the enhancement of interface strength are analyzed. Our work provides a deep understanding of the interface structure, deformation and failure and will be useful for selecting suitable surface coupling agents in enhancing the interface strength of polymer composites.

Processing and properties of hollow glass microsphere particulate-filled PA2200 composites produced by selective laser sintering

Selective laser sintering (SLS) to prepare composites by adding filler into polymer is an effective method to save costs and reinforce the sintered parts. This article investigated the fabrication of PA2200 composites filled with different volume fractions of hollow glass microsphere (HGM) by SLS. HGM was prepared by silane coupling agent surface treatment. The particle size distribution, microstructure, thermal and mechanical properties of PA2200/HGM composites were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and tensile experiment. The results indicated that the density of the composite was significantly reduced compared to the neat PA2200 and the density decreased with the HGMs content increasing. HGM improved the warping deformation in the process of sintering. The tensile modulus increased while tensile strength and elongation at break decreased as a function of HGM volume fraction in a certain range. This work indicated that thermal properties and tensile properties of polyamide-matrix composites can be reinforced by adjusting HGM content, and PA2200/HGM composite powder is a good material for SLS with less density and lower cost.

Titanate coupling agent surface modification effect on the magnetic properties of iron-based alloy powder coil prepared using screen printing

A molded-type coil is prepared by filling and dry pressing granulated alloy magnetic powders directly onto enameled wire. As the molded-type coil is developed toward miniaturization, the granules consisting of magnetic powder and organic binder cannot uniformly fill the small space in the coil center column during molding. This leads to a porous microstructure or cracks. In this study, magnetic alloy powder coils were prepared using a screen-printing process using high-solid-content magnetic pastes. The magnetic powder was surface-modified with titanate coupling agent to improve the magnetic powder and epoxy resin compatibility, thereby improving magnetic powder mixing with epoxy resin and reducing the high solid content magnetic paste viscosity. The experimental results showed that the relative density and magnetic properties (such initial permeability, core loss, and coercivity) can be significantly enhanced using titanate coupling agent surface modification.

Preparation and Thermomechanical Properties of Ketone Mesogenic Liquid Crystalline Epoxy Resin Composites with Functionalized Boron Nitride.

In order to enhance the thermomechanical behaviors of epoxy molding compounds, the hexagonal boron nitride (h-BN) fillers were incorporated in a ketone mesogenic liquid crystalline epoxy (K–LCE) matrix to prepare a high-performance epoxy composites. The h-BN was modified by surface coupling agent 3-aminopropyltriethoxysilane (APTES). The grafting of silane molecules onto the surface of BN fillers improved the compatibility and homogeneous dispersion state of BN fillers in the K–LCE matrix with a strong interface interaction. The surface-modified BN fillers were characterized using Fourier transform infrared spectroscopy. The thermomechanical properties and morphologies of K–LCE/BN composites loading with different contents of modified BN fillers, ranging from 0.50 to 5.00 wt%, were investigated. These results show that modified BN fillers uniformly dispersed in K–LCE matrix, contributing to the enhancement in storage modulus, glass transition temperatures, impact strength and reduction in the coefficient of thermal expansion (CTE). The thermal stability and char yield of the K–LCE/BN composites were increased by increasing the amount of modified BN fillers and the thermal decomposition temperatures of composites were over 370 °C. The thermal conductivity of the K–LCE/BN composites was up to 0.6 W/m·K, for LC epoxy filled with 5.00-wt%-modified BN fillers. Furthermore, the K–LCE/BN composites have excellent thermal and mechanical properties compared to those of the DGEBA/BN composites.

Surface treatment of jute fibre using eco-friendly method and its use in PP composites

Abstract Jute fibre finds application as filler in many polymer matrices. Polypropylene(PP) is a polyolefin which has found to be used extensively in applications where low density and optimum strength is require because of it optimum melting point and ease of processability. Jute has been used as filler in PP. However due to problem in interface adhesion of PP and jute, surface treatment and coupling agent have been used to improve interfacial adhesion. But in all these methods chemicals are used to improve the interfacial adhesion which affect environment and also the people working with it. Here we have used a eco-friendly method to modify the surface of jute. The method involves the treatment of fibre using enzyme. Jute fibre was treated using various concentration of the enzymes and optimum enzyme content was chosen. Modified Jute fibre was used in different concentrations in PP and mechanical properties and thermal properties of the composites were studied.

Mode II Interlaminar Fracture Properties of Treated Silk Fibre/ Epoxy Composites at Low and High Temperature Range

Composite materials have a wide range of applications including as an automotive components. In certain applications it is exposed to various heat conditions and might affect its mechanical properties. It is important to be able to predict the behavior of the composites under different temperature settings in order to prevent failure. The GIIC properties of composite epoxy laminate with silk fibre at various temperatures have yet to be investigated by any researcher. This study was carried out to analyse the Mode II interlaminar fracture properties, GIIC of the silk fibre / epoxy composite materials when treated with silane coupling agents at different test temperatures. This property is important since it provides the measure of the material’s resistance to delamination crack propagation. Composite specimens were produced using compression moulding technique with sixteen layers of silk fabric. The matrix is an epoxy D.E.R 331 and Hardener Joint mine 905-3S. The weight ratio of mixing epoxy and hardener is 2:1. Six sets of sample were prepared using silk fibre which has undergone surface treatment for 24 hour using silane coupling agent surface treatment solution. Specimens were tested by Instron Universal Testing Machine using a three-point bending based on an end notched flexural (ENF) method. The tests were carried out at six different temperatures which are at 20 oC, 23 oC, 26 oC, 38 oC, 50 oC and 75 oC. The temperature of the specimens during testing was monitored using a thermal imager in order determine the exact test temperature. It was found that as the temperatures increases, the mode II fracture toughness decreases by up to 71%. The length of crack propagation shows that higher temperature leads to longer crack length. This could be due to the residual tension between the fibre and matrix as they have different thermal coefficient of expansion.

The influence of surface treatment on the tensile and tribological properties of wood fiber‐reinforced polyimide composite

In this paper, the effect of coupling agent surface treatment of wood fiber on tensile and tribological property of wood fiber‐reinforced thermoplastic polyimide (PI) composites was experimentally investigated. Experimental results revealed that coupling agent surface treatment could effectively improve the interfacial adhesion between wood fiber and PI matrix. Compared with the untreated wood fiber/PI composite, the coupling agent‐treated composite had better interfacial adhesion. The fracture surfaces and worn surface of samples were investigated by scanning electronic microscopy to analyze the effects of surface treatment methods.

Measuring the influence of materials composition on nano scale roughness for wood plastic composites by AFM

Abstract Composition of mango wood Polypropylene composites (WPCs) are prepared through melt compounding with the help of micro conical twin screw co-rotating extruder then injection molding of WPCs pellets. Polymer matrix composites are formulated for five compositions with a different weight ratio of wood, virgin polypropylene, recycled polypropylene and coupling agent. Average roughness (Ra), mean peak-to-valley height (Rz) and maximum roughness (Rmax) used to evaluate surface characteristics of samples by AFM. Also measures the 3D surface and surface roughness profile to examine the same. Result from this work clearly shows that recycled Polypropylene based composites with and without coupling agent have a smooth surface in comparison with virgin Polypropylene based composites for same operating variable conditions. The surface smoothness of WPCs improved with decreasing of wood flour content for all samples. By addition of coupling agent surface smoothness of the WPCs increases and the value of Ra decrease from 2.17 to 1.04 nm for recycle polypropylene wood based composite. Surface of composites is also examined with the help of FESEM images. FESEM feature proved that MAPP coupled is shown good bonding strength and smoothness in comparison to none coupled composite for the same class.

Effect of Silane Coupling Agent Surface Modified Layered Double Hydroxides on Properties of Bitumen

Layered double hydroxides (LDHs) surface modified by silane coupling agent KH550 were prepared to modify bitumen, the surface modified LDHs (KH550-LDHs) were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD). The effect of KH550-LDHs and LDHs on physical and anti-ageing properties of bitumen was evaluated by means of physical test. The results of FTIR showed that KH550 had successfully grafts onto the surface of LDHs, and XRD result showed that KH550 had little effect on the crystal structure of LDHs. The storage stability test showed that KH550-LDHs dispersed better homogeneously and existed more stable than LDHs in bitumen. The physical properties tests indicated that high and low temperature properties of bitumen were improved compared with LDHs. After UV aging with the addition of KH550-LDHs, the increase rate of softening point slowed remarkably, the reduction rate of ductility declined evidently compared with LDHs. Aging indices (softening point increment and ductility retention rate) show that KH550-LDHs exhibited better improvement than LDHs in UV aging resistance of bitumen, implying more effective modification of KH550-LDHs which is due to the enhanced compatibility between KH550-LDHs and bitumen.

Preparation of Stabilizer-Free Silver Nanoparticle-Coated Micropipettes as Surface-Enhanced Raman Scattering Substrate for Single Cell Detection.

In this work, we established a convenient while reproduceable method for stabilizer-free silver nanoparticle (AgNP)-coated micropipettes by the combination of magnetron sputtering and surface coupling agent. The clear surfaces of the AgNPs are beneficial for absorbing biological or functional molecules on their surfaces. By optimizing the operating parameters, such as sputtering current and sputtering time, the tip of micropipettes coated with AgNPs exhibits excellent surface-enhanced Raman scattering (SERS) performance. Finally, the Raman spectra of a single A549 lung adenocarcinoma cell are successfully acquired by these advanced SERS-active micropipettes.

Silanized aryl layers through thiol-yne photo-click reaction.

Nanometer-scale multilayered coatings were prepared by sequential surface reactions on gold plates. First 4-ethynylphenyl organic layer was electrografted from the parent diazonium tetrafluoroborate salt providing reactive alkynylated gold plate (Au-Y). The latter served for clicking mercaptosilane via a thiol-yne photo-triggered reaction to obtain alkoxysilane-functionalized surface. The trialkoxysilane top groups in turn served as anchor sites for the final sol-gel coating resulting from the surface reaction between aminopropylsilane and tetraethoxysilane (TEOS). It is demonstrated that two coupling agents, namely, aryl diazonium salt and silane, can be coupled using photo-triggered thiol-yne click reaction, resulting in robust multilayered coatings. In addition, the process is versatile in that it offers the possibility to design patterned surfaces. The top sol-gel layer can in turn be reacted with aminosilane, therefore providing a reactive and functional surface that can be used for different applications given the reactivity of amine groups. This approach opens new avenues for photo-triggered click reactions of aryl layers from diazonium salts. It shows that the new class of surface modifiers and coupling agents has much to offer and continues to be renewed for achieving tightly bound, reactive top coatings.