Experimental investigation of the factors influencing the polymer-polymer bond strength during two-component injection moulding

Two-component injection moulding is a commercially important manufacturing process and a key technology for combining different material properties in a single plastic product. It is also one of most industrially adaptive process chain for manufacturing so-called moulded interconnect devices (MIDs). Many fascinating applications of two-component or multi-component polymer parts are restricted due to the weak interfacial adhesion of the polymers. A thorough understanding of the factors that influence the bond strength of polymers is necessary for multi-component polymer processing. This paper investigates the effects of the process conditions and geometrical factors on the bond strength of two-component polymer parts and identifies the factors which can effectively control the adhesion between two polymers. The effects of environmental conditions on the bond strength are also investigated. Investigation shows that melt and mould temperatures are vital process parameters that influence the bond strength. Besides this, surface roughness of the first-shot part and environmental factors like moisture have profound influence on the bonding of the two materials. The selections of materials and environmental conditions were done based on the suitability of MID production, but the results could be useful for two-component polymer processing for a wide range of industrial applications. The results and discussion presented in this paper are only valid for the two-component plastic parts moulded by over moulding in cavity-transfer process.