Adhesion of thermoplastic elastomer on surface treated aluminum by injection molding

A non-destructive technique using digital holographic vibrometry and Lamb waves for quality determination of polymer-metal laminates

We used digital holographic vibrometry (DHV) as a non-destructive method to detect debonding areas in laminates made of aluminum and polymer (polylactide, polyvinylidene fluoride or polycarbonate). At low frequencies (up to 30 kHz) \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_0$$\end{document}A0 Lamb waves were excited and the amplitude and the phase patterns of the vibration of the sample were simultaneously registered for metal and polymer side of the laminate. Based on these patterns debonding areas in laminates were localized. The transmission properties at low frequencies were also studied in terms of: the frequency range for which regular Lamb waves have been observed, Lamb wave amplitudes and Lamb wave propagation velocity depending on the frequency. We have shown that these properties also change when a defect occures in the laminate. Even when we could not localize the defect it was still possible to detect if a sample was damaged based on the behaviour of the Lamb waves.

The Influence of Thermal Treatments on Anchor Effect in NMT Products

The anchor effect in nanomolding technology (NMT) refers to the effect that polymer nanorods in nanopores on metal surfaces act as anchors to firmly bond the outside polymer components onto the metal surface. In this work, the influences of thermal treatments on the anchor effect are studied at microscopic level from the perspective of interfacial interaction by a model system (poly(n-butyl methacrylate) (PBMA) and alumina nanopore composite). The differential scanning calorimeter and fluorescence results indicate that the formation of a dense polymer layer in close contact with the pore walls after proper thermal treatments is the key for a strong interfacial interaction. Such polymer layers were formed in NMT products composed of PBMA and aluminum after slow cooling or annealing, with an up to eighteen-fold improvement of the interfacial bonding strength. The polymer chains near the nanopore walls eliminate the thermal stress induced by the mismatch of thermal expansion coefficients through relaxation over time and remain in close proximity with the pore walls during the cooling process of nanomolding. The above dynamic behaviors of the polymer chains ensure the formation of stable interfacial interaction, and then lead to the formation of the anchor effect.

Research on Surface Treatment and Interfacial Bonding Technology of Copper-Polymer Direct Molding Process

To realize the connection of copper and Polyphenylene sulfide (PPS) by metal–polymer direct molding, this paper combined anodic oxidation and chemical corrosion to treat the surface of copper, and carried out the injection molding experiment. An orthogonal experimental arrangement was used to identify the optimal electrolyte and etching solution for preparing a microstructure on a copper surface. The bonding and fracture mechanisms of the copper–polymer assembly were investigated through injection molding experiment and SEM technology. The results revealed that the phosphoric acid concentration had the most significant effect on the microstructure quality and etching solution containing 20% phosphoric acid produced a uniform microstructure with 25.77% porosity and 5.52 MPa bonding strength. Meanwhile, SEM images of the interface from bonding to fracture in the copper–polymer assembly indicated a well-filled polymer in the microstructure with a mainly cohesive fracture mode.

Deformation Mechanism in Mechanically Coupled Polymer-Metal Hybrid Joints

In this, work, metal inserts were joined with polyamide 6 by using the injection-molding technique. The metal parts, made of steel grade DC 04, were mechanically interlocked with polyamide 6 (PA6) by rivets as a mechanical connection between both components in the form of s polymer filling the holes in the metallic parts. The mechanical-interlocking joints made of steel/PA6 were mechanically tested in a tensile-lap-shear test. The damage behavior of the joined materials in relation to rivet number and position on the metal plate was studied. The observation of rivet deformation was also conducted by infrared IR thermography. The study showed that, for polymer–metal joined samples with fewer than three rivets, the destruction of rivets by shearing meant sample damage. On the other hand, when the polymer–metal joint was made with three or four rivets, the disruption mechanism was mostly related to the polymer part breaking. The maximal values of the joint’s failure force under tensile-shear tests were achieved for samples where three rivets were used. Moreover, strong correlation was found between the surface temperature of the samples and their maximal force during the tensile-lap-shear test.

Mechanical Property and Structure of Polypropylene/Aluminum Alloy Hybrid Prepared via Ultrasound-Assisted Hot-Pressing Technology

The polypropylene/aluminum alloy hybrid was prepared via an ultrasonic-assisted hot-pressing technology (UAHPT). The mechanical property and structure of the UAHPT processed polypropylene/aluminum alloy hybrid were explored by the tensile shear test, scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. Prior to obtaining the UAHPT processed hybrid, the microporous structures were prepared by the anodic oxidation in a phosphoric acid solution in which the polypropylene (PP) melt flowed into and formed the micro mechanical interlocking structure at the interface of polypropylene/aluminum alloy. The effects of bonding temperature, pressing pressure, ultrasonic amplitude, and ultrasonic time on the bonding properties of the hybrids were investigated via orthogonal experiment. The UAHPT processed hybrid was strengthened and the maximal tensile shear strength reached up to 22.43 MPa for the polypropylene/aluminum alloy hybrid prepared at the optimum vibration processing parameters.

Simulation Study of the Effects of Nanoporous Structures on Mechanical Properties at Polymer-Metal Interfaces

We investigated the effect of nanopores on the adhesion behavior at polymer-metal interfaces by molecular dynamics simulation. The effects of shear and extension behavior were examined. In the shear mode, samples with porous substrates showed larger shear forces than those with flat substrates. Meanwhile, the breaking strengths in the extension mode were almost the same for systems with flat and porous substrates. The similar behavior in the extension mode was ascribed to the formation of voids in the polymer layer, which was related to the increase of total system volume and not affected by the presence of pores. We also investigated the relationship between the mechanical properties of polymer-metal interfaces in the shear mode and pore size in detail. Even a very shallow pore with a depth of 0.5 nm produced a large shear force comparable to that of a pore with a depth of 2.0 nm. The shear force increased gradually as the pore diameter became wider. These simulation results revealed that the adhesion forces between polymers and rough metal surfaces are not simply related to the interface area but depend on the pulling mode, pore size, and polymer chain length in a complicated manner.

Effect of the temperature gradient on the interfacial strength of polyethylene/polyamide 6 during the sequential injection molding

Effect of the temperature gradient on the interfacial strength of polyethylene (PE)/polyamide 6 (PA6) during the sequential injection molding (SIM) was investigated in this article. PE grafting with maleic anhydride (PE- g-MAH) was added into PE matrix to enhance the interfacial strength through the formation of the copolymer at PE/PA6 interface. The results showed that the reaction at PE + PE- g-MAH/PA6 interface was incomplete due to the steep temperature gradient built from the melt (the second part) to the solid (the first part) during SIM. However, the interfacial reaction proceeded further during annealing through the diffusion of the reactive groups into PE + PE- g-MAH/PA6 interface so that much more copolymers were formed at PE + PE- g-MAH/PA6 interface, resulting in obvious improvement of the interfacial strength after annealing. It was also found that the relationship between interfacial strength and PE- g-MAH content was a linear relation through data fitting under gradient cooling during SIM. However, the relationship became the square relation after annealing at 220°C for 10 min. Through the rheological analysis and morphological observation, it was concluded that the interfacial temperature was a very important factor to control the interfacial strength during SIM.