Effect of nano-texturing on adhesion of thermoplastic resin against textured steel plate

Long Fiber Thermoplastic-Direct (LFT-D), a new stamping method, has been developed to achieve the short cycle-time manufacturing of Carbon-Fiber-Reinforced thermoplastics (thermoplastic CFRP). In LFT-D method, to shorten cooling time is one of the effective way for achieving more productive manufacturing. During ejection sequence in the LFT-D, thermoplastic resin parts adhere stronger than previous method. High adhesion affects smoothness of the component surface, cycle-time and requested specifications of equipment. So, it is required to reduce the adhesion between the metal mold and thermoplastic resin. This paper reports the effect of nano-texturing on adhesion of thermoplastic resin against the textured steel around glassy-transition temperature. Experimental results show that the adhesion strength increases proportionally with the ratio of contact area. The lowest adhesion strength on nano-textured surface is 0.18 MPa, which is 66% lower than that of flat surface. It is clarified that surface adhesion energy increases with the ratio of contact area A_contact to circumference of contact area L_{circumference}.