?-Irradiated poly(tetrafluoroethylene) particle-filled low-density polyethylene. II. UV stability of LDPE in the presence of 2�-PTFE powder and silane coupling agents

Abstract

Ultraviolet (UV) stability of ␥-irradiated poly(tetrafluoroethylene), 2°-PTFE, powder-filled low-density polyethylene (LDPE) was studied in this work. The mechanical and thermal properties of 2°-PTFE powder-filled LDPE were discussed in our previous work (Akınay and Tinçer, 1999). It already has been shown that silane coupling agents (SCAs) result in improvements in mechanical properties. The UV stability of these samples was followed by a comparision between strain at break measured after UV irradiation and the initial strain at break, in terms of their ratio defined as residual elongation. The development of carbonyl index was also determined by infrared measurements. To get further UV stability, a hindered amine light stabilizer (HALS) was also used. Whereas addition of 2°-PTFE slightly enhanced the UV stability of LDPE, mercapto type silane (A-189) treatment appeared to increase the UV stability compared with the other types of silane treatments. HALS highly improved the UV stability of untreated and silane-treated 2°-PTFE-filled LDPE at given UV irradiation time. Although we observed some fluctuations in the experimental data of HALS and SCA treated 2°-PTFE-filled LDPE, the coaddition of HALS and SCAs showed synergetics effects in the UV stability compared with the separate additions.

Effect of Additives on Weathering

“…21 Particulate polytetrafluoroethylene added to LDPE increased its resistance to UV radiation. 27 Tensile strength was reduced by one half and toughness by two thirds when polyethylene containing wood flakes was exposed for 205 days. Water absorption and desorption and environmental stress cracking caused the deterioration.…”

Preparation and characterization of poly(ethylene terephthalate) powder-filled high-density polyethylene in the presence of silane coupling agents

“…Zimmerman 25 showed that an extensive autocatalytic reaction by hydrolytic cleavage of polyester chains resulted in carboxyl groups under isothermal heating. Similar results were reported earlier by Buxbaum,26 and the degradation mechanism was also reviewed by Jabarin. 27 Consequently, The silane treatement is expected to facilitate extensive hydrolysis and condensation, also possible alkoxy exchange reactions on the surface of the PET particles.…”