Abstract:
Chloroprene (CR) rubber base contact adhesives are an industrially important branch of adhesives commonly used in structural applications e.g. footwear, plastic, leather, automobile, construction industries etc. Various efforts have been made to improve its bond strength for multiple substrates. Variation in processing parameters and addition of useful ingredients may be helpful in increasing peel strength of joined substrates. Incorporation of nanoscale reinforcement is a potential means to move in this direction.
In the current study, an effort has been made to incorporate multiwall carbon nanotubes (MWCNTs) in small quantity and to optimize its ratio in order to obtain improvement in bond strength. The objective of this research was to enhance peel strength on flexible substrates and to improve its resistance at high temperature (≤ 100o C). Most of the adhesives show good performance in normal conditions but their application is limited in extreme ageing environment. The research work was divided into three parts. In first part, a polychloroprene rubber-based contact adhesive was prepared. Then, in second step, the dispersion of multi- walled carbon nanotubes was done using N, N-Dimethylformamide solvent. In final step, dispersed MWCNTs were added in formulated polychloroprene adhesive to prepare a nanocomposite adhesive. Multiple formulations were made using various grades of polychloroprene, along with varying experimental conditions. For example, phenolic resin, MgO, anti-oxidant and solvents were added in various proportions. The best results were obtained with 65-phr phenolic resin and incorporation of MWCNTs up to 1 %. The solids contents 50-52 % in prepared adhesive were found to be optimum. The peel tests after exposure to aggressive environmental conditions showed that nanocomposite adhesive had greater thermal stability and weather resistance compared with commercially available adhesives.
