Studies On Multi-Layer Automotive Plastics Fuel Tank Production And Adhesion Behavior

Multi-layer plastic Automotive fuel tank has gained widespread use in the world as well as in China for Automotive application because they can be formed in complicated shapes with good process-ability, are corrosion resistant, are light weight, have high puncture resistance, and are relatively low cost and safety. Multi-layer plastics fuel tank is made of different polymers with structure: (inside) HDPE/Tie/EVOH/Tie/HDPE regrind/HDPE co-extrusion blown moulding by 6 extruders respectively. The adhesion among different layers particularly between EVOH and adhesive is one of key points to make high performance barrier plastics fuel tank.This article focused on multi-layer fuel tank production and adhesion behavior and some factors heavily affecting the adhesion of multi-layer fuel tank were analyzed in terms of grafted maleic anhydride content, processing temperature, output, thickness of adhesive, and the structure of fuel tank itself, and particularly discussed on adhesion aging behavior of fuel tank in service and its importantance.We learnt from our study that high maleic anhydride(MAH) content of grafted polyethylene results in high reactivity between EVOH and adhesive so that the peeling strength enhanced from 50N/10mm at around 1200ppm MAH content to 81N/10mm at 4000ppm MAH content, which means big influence for peel strength with MAH content. The adhesion increased sharply while processing temperature is above 205℃, the high temperature probably speeds up the reactive of MAH with -OH group of EVOH. The thickness difference of adhesive nearly gives no effect on peeling strength. To improve output of production or reduced production cycle time will affect the time of reaction so that the peeling strength will drop slightly. Furthermore, The peeling strength heavily depend on the structure of fuel tank itself such as HDPE thickness or EVOH position resulted from the different geometry of T peeling test. The peeling strength measured is not only given by adhesion on interfacial, but also contributed by plasticity of the specimen itself (deformation of peeling arms bending during peeling test).With the knowledge and experience learnt from our study in Laboratory to adjust processing parameters for production build-up of multi-layer fuel tank. Some problems related to the multi-layer fuel tank production were also discussed with a view to solving the existing problem and making qualified high performance barreier plastic fuel tank.The objective of this study is to help and promote our plastic fuel tank production as well as automotive industry development in China.