gamma-irradiated poly(tetrafluoroethylene) particle-filled low-density polyethylene. I. Effect of silane coupling agents on mechanical, thermal, and morphological properties

Poly(tetrafluoroethylene) (PTFE) scraps were recovered as a filler material for low-density polyethylene (LDPE) after they were degraded by Co-60 gamm a-rays under atmospheric conditions to make small-size powder. The powder P TFE, which was called secondary PTFE (2 degrees-PTFE), was melt mixed with LDPE and then extruded to obtain 200 mu m films. The mechanical and thermal properties and also the morphology of the fractured surface of these 2 deg rees-PTFE-filled LDPE were studied. It was found that the addition of 2 deg rees-PTFE resulted in thermofilm property of LDPE but it slightly decreased the thermal oxidative temperature of LDPE. The tensile strength and ultima te elongation of LDPE were found to decrease with the addition of 2 degrees -PTFE. However, when it is compared to the addition of virgin PTFE into LDP E, 2 degrees-PTFE shows better mechanical properties due to the presence of oxy groups which are capable of interacting with the main matrix. A furthe r improvement in mechanical properties was achieved by silane coupling agen t treatment of 2 degrees-PTFE. Silane coupling agents were found to enhance the interfacial adhesion between 2 degrees-PTFE and LDPE. The study on the fractured surfaces by scanning electron microscope revealed this adhesion between these two polymers. (C) 1999 John Wiley & Sons, Inc. J Appl Polym S ci 74: 866-876, 1999.