Sabbir Ahmed

Plasma nitriding on titanium surface for adhesion promotion

Abstract This investigation highlights the influence of plasma nitriding on titanium surface in order to improve its interfacial adhesion strength with epoxy and epoxy nanocomposites adhesive. Surface energy of titanium increases considerably due to plasma nitriding implantation. X-ray photoelectron spectroscopy studies indicate the formation of various titanium nitrides, which are responsible for the increase in surface polarity. A reduction in equilibrium contact angle improve wetting on the surface and proper intimacy of the adhesive layer with two joining titanium surfaces. The atomic force microscopic study indicates smoothening of treated titanium surface. Thus, a greater surface area of contact with the adhesive layer helps uniform splitting of adhesive over the two titanium surfaces. A further improvement in bond strength is achieved on incorporation of 5% nanosilicate as reinforcement within the adhesive.

Epoxy–novolac interpenetrating network adhesive for bonding of plasma-nitrided titanium

This investigation highlights rationale to synthesize epoxy–novolac adhesive by novel interpenetrating network (IPN) technique. Physicochemical characteristics of the plain adhesive and IPN adhesive were carried out by Fourier transform infrared spectroscopy and thermal gravimetric analysis. Performing lap-shear test carried out plasma-nitrided titanium was fabricated with these adhesives and mechanical property of these adhesives. The blend of epoxy and novolac was optimized at 4:1 ratio, and the formation of IPN was confirmed by the suppression of creep with reference to neat epoxy and its swelling behavior. The adhesive with IPN shows significantly higher thermal stability than epoxy and leaves higher amount of residuals at the elevated temperature. Due to surface modification of titanium by plasma nitriding, wetting characteristics of titanium increases considerably and consequently, there was a significant increase in lap-shear strength adhesively of bonded titanium substrate.

Characteristics of IPN Adhesive Bonding of Polyether Imide to Titanium for Aerospace Application

AbstractThis investigation highlights the performance of epoxy-novolac interpenetrating polymer network (IPN) adhesive bonding of surface-modified polyether imide (PEI) to titanium (Ti) under eleva...

Adhesion Characteristics On Anodized Titanium And Its Durability Under Aggressive Environments

In this investigation, an attempt has been made to improve the interfacial adhesion characteristics of titanium (Ti) surface at elevated temperature and in aqueous salt solution. In order to ensure the presence of titanium oxide coating on the surface of titanium, anodization on titanium was carried out by sodium hydroxide. This oxide coating etches the surfaces of titanium. These etching surfaces of titanium increase the surface energy and surface roughness of the titanium. Physicochemical characteristics of surface modified titanium were carried out by X-ray photoelectron spectroscopy (XPS) study and the results reveal that there is a significant increase in oxygen functionalities due to anodization. The oxide etching on the surface of anodized titanium is further confirmed by scanning electron microscopy (SEM) study. The contact angle and surface energy are measured by the use of two liquids namely water and glycerol. It is observed that the formation of oxide not only improves the surface energy of titanium but also protects the surface of titanium when exposed to aggressive environments. The lap-shear tensile strengths of two anodized titanium surfaces were fabricated by adhesive. There has been significant improvement in the adhesive bond strength, and subsequently in the durability of adhesive bonded joint, of titanium when exposed to aggressive environments.

Effect of Atmospheric Pressure Plasma Modification on Polyimide and Adhesive Joining with Titanium

This investigation highlights the effect of surface modification on polyimide by atmospheric pressure plasma treatment with different exposure time. Surface modification of polymer by plasma treatment essentially creates physical and chemical changes such as cross-linking and formation of free radicals. It also forms oxygen functionalization in the form of polar groups on polymer surface, hence improving the wetting and adhesion properties. It is observed that surface energy of the polymer increases with increasing exposure time of atmospheric pressure plasma. However, prolonged exposure time of plasma results in deterioration of the surface layer of polyimide resulting in degradation and embrittlement. Scanning electron microscopy and atomic force microscopy analysis reveal that there is a considerable morphological change on the polymer surface due to atmospheric pressure plasma treatment. X-ray photo electron spectroscopy analysis reveals that the oxygen functionalities of polymer surface increases significantly when polyimide is exposed to atmospheric pressure plasma. Untreated and atmospheric pressure plasma-treated polyimide sheet are adhesive bonded by employing polyimide adhesive as well as with titanium substrate. Due to surface modification of polyimide, it is observed that there is a significant increase in lap shear tensile strength, and therefore, this technology is highly acceptable for aviation and space applications.

Characteristics of simultaneous epoxy-novolac full interpenetrating polymer network (IPN) adhesive

Abstract In this investigation, an attempt has been made on the synthesis of epoxy-novolac IPN adhesive simultaneously by using full interpenetrating polymer network (IPN) technique. Novolac resin is mixed in different weight ratios with respect to epoxy resin. Thereafter, both the resins are cross-linked with their respective cross linker agents simultaneously. This epoxy-novolac IPN adhesive is characterized by various studies such as swelling; cross-link density; dynamic mechanical and thermal analysis and fourier transform inferred spectroscopy (FTIR). The swelling study reveals that the epoxy-novolac IPN adhesive is synthesized through full IPN technique successfully. The cross-link density result shows that epoxy- novolac (4:1) IPN adhesive has greater interpenetration than other epoxy-novolac IPN adhesive systems. Dynamic mechanical and thermal analysis (DMTA) result exhibits that epoxy-novolac (4:1) IPN adhesive is stiffer than another epoxy-novolac IPN adhesive system. The result of FTIR proves that epoxy-novolac IPN adhesive undergoes simultaneously. The results of all these characterization techniques conclude that epoxy-novolac IPN adhesive system with 4:1 ratio is considered to be the best IPN adhesive compared to others epoxy-novolac IPN adhesive systems.

Physicochemical Characteristics of Solvent Vapor Bonded Polycarbonate

In this investigation attempt have been made to develop high throughput state of the art vaporized solvent bonding of transparent polymer such as polycarbonate. Focus has also been given to understand the influence of aggressive chemical environments on the interface and bond strengths. Different solvents such as acetone, dichloromethane, methyl ethyl ketone and chloroform have been used for vaporized solvent bonding of the polymer. Dichloromethane appears to be the best solvent for polycarbonate because the solubility parameter of dichloromethane closely matches with polycarbonate. Therefore, due to stable molecular structure of polycarbonate under vaporized solvent bonding, it is ensured that the physicochemical interaction between polycarbonate and solvent vapor resists the failure of bond when exposed to aggressive environment such as under Ringer’s solution. The Fourier transform infrared spectroscopy peak indicates the presence of phenolic O–H functionality, which may attribute to ion induced-dipole interaction of solvents with polycarbonate. There is a considerable increase in bond strength with increasing pressure and scanning electron microscopy images clearly reveals that failure of solvent vapor bonded polycarbonate is essentially cohesive from the polymer resulting in significant improvement in bond strength.

Interpenetrating polymer network adhesive bonding of PEEK to titanium for aerospace application

Abstract This investigation highlights the rationale of epoxy-novolac interpenetrating polymer network (IPN) adhesive bonding of low-pressure plasma treated polyether ether ketone (PEEK) to plasma nitrided titanium for aerospace application. Physico-chemical characterization of surface modified PEEK is carried out by surface energy measurement and X-ray photoelectron spectroscopy (XPS) analysis. Lap shear tensile tests are carried out to measure mechanical properties such as lap-shear tensile strength, Young’s modulus, percentage elongation at break (% EB) and toughness of the adhesive bonded PEEK to titanium joint. XPS analysis reveals the presence of the oxygen (O) functional group into the plasma treated PEEK surface. This polar functional group O increases the surface energy on the plasma treated PEEK surface, and consequently, the adhesive bond strength is enhanced. The values of Young’s modulus, % EB and toughness of epoxy-novolac IPN adhesive bonded plasma treated PEEK to plasma nitrided titanium are increased considerably in respect to epoxy-novolac IPN adhesive bonded untreated PEEK to untreated titanium joint. Therefore, the present investigation concludes that the adhesive bond strength not only depends on the surface characteristics of PEEK and titanium, but also on the cohesive properties of the adhesive.

Effect of TiN-deposition on adhesion characteristics of aluminium

ABSTRACT This investigation highlights on surface modifications and adhesive bonding of aluminium. The surface of the aluminium substrate is modified by magnetron sputtering and nanoparticle reinforcements are employed into the adhesive and their effects on adhesive strength are examined. Owing to the concern of durability of the aluminium surface, adhesive joints are still questionable for their widespread use in structural applications. Various environmental conditions affect properties of adhesives and their performance may degrade over time when adhesive joints are exposed to varying moisture and temperature conditions. Modified aluminium surfaces are examined by morphological techniques to understand the result of deposition on the morphology of substrate. Surface modified samples are subjected to harsh environments and analysed by energy dispersive spectra and surface durability is quantified by corrosion penetration rate. The effect of nano-reinforcements in adhesives on bond durability is examined when the bonded joints are subjected to the harsh environment.

Comparative studies of solvent bonding and adhesive bonding for fabrication of transparent polymers

This investigation highlights rationale of solvent bonding and adhesive bonding for fabrication of a transparent polymer such as polycarbonate with a high-throughput process. Studies under ultra violet spectra and visible spectra reveal that in comparison with adhesive bonding of a polymer, solvent diffusion bonding is more transparent. Polycarbonate is hydrophilic in nature resulting in a low contact angle of water as well as the presence of polar functional groups on the polymer surface. It is observed that a lap shear tensile strength of a solvent bonding polymer is significantly higher than that of an acrylic adhesive bonded polycarbonate, and fabrication of polycarbonate by solvent bonding merely takes few seconds. Solvent bonding of a polymer results in a cohesive failure from polymer as analyzed under the scanning electron microscopy, this is why solvent bonding shows a significantly higher bond strength.