Polyurethane structural adhesives applied in automotive composite joints

Abstract

In recent years structural adhesives technology has demonstrated great potential for application due to its capacity to transform complex structures into solid unitary and monolithic assemblies using different materials. Thus, seams or joints integrate these structures providing, besides a reduction in weight, a considerable increase in the mechanical resistance and stiffness. The increase in the industrial use of structural adhesives is mainly due to their ability to efficiently bond different materials in an irreversible manner, even replacing systems involving mechanical joints. In the automobile industry structural adhesives have been widely used for the bonding of metal substrates, thermoplastics and composites, frequently employing these in combination, particularly glass fiber and polyester resin composites molded using RTM and SMC processes. However, the use of urethane structural adhesives in applications involving composites and thermoplastics has been the subject of few investigations. In this study the effects of temperature and time on the shear strength of RTM, SMC and ABS joints, applying temperatures of -40, 25, 80, 120 and 177 °C and times of 20 minutes and 500 hours, were determined. The objective was to evaluate the performance under extreme conditions of use in order to assess whether these joints could be used in passenger or off-road vehicles. The results showed that the urethane structural adhesive promoted the efficient bonding of these materials, considering that due to the high adhesive strength the failures occurred in the substrates without adversely affecting the bonded area. For each test condition the joint failure modes were also determined.

A fast UV-curable PU-PAAm hydrogel with mechanical flexibility and self-adhesion for wound healing

“…15 mm  15 mm fullthickness skin defects were created by established protocol. 40 PP-50 and PP-30 hydrogels were used as experimental groups, and the control group was set without any treatment. Aer 3, 6, 9, 13 and 17 days, the wound samples were harvested to detect the regeneration of skin.…”

Shear Stress Distribution in Double-lap Adhesive Joints Reinforced with Nylon Fabric: Numerical Investigation

“…In numerous industrial applications (e.g., automotive [4], naval [5] and aerospace [6]), these characteristics are fundamental and therefore adhesive technology takes a preferential role over traditional joining methods, such as bolted or riveted joints [7][8][9]. Some of the most studied adhesive joints are singlelap (SLJ) and double-lap (DLJ) types [10][11][12]; both types are used to study adhesive shear joint behaviour [13].…”

Comparison of Two-Component Silyl-Terminated Polyether/Epoxy Resin Model and Complete Systems and Evaluation of Their Mechanical, Rheological and Adhesive Properties

“…Polyurethane adhesives are known for their short forming time necessary for the development of the strong bond, compatibility with a broad range of different materials and easy and clean handling, making them more advantageous over many other polymer adhesives. Polyurethane adhesives are used for a broad range of applications, including textiles, aerospace, food packaging, automotive, defense and other high-performance industry sectors, because of their excellent durable adhesion [3][4][5][6][7][8][9]. Currently, there is practically no alternatives for polyurethane systems as materials with high tensile strength values (σ break > 3 MPa).…”