Effect of Additives on Mechanical Properties and Photo-Stability of Filament-Wound Glass Fiber Reinforced Epoxy Pipes

This paper studied the effects of 4 types of additives, UV-absorber, antioxidant, carbon black, and flame retardant, on mechanical properties and UV- stability of glass fiber reinforced epoxy (GRE) pipes prepared by filament winding process using a MTHPA (Methyl Tetrahydrophthalic Anhydride) as a catalyst. The amount of additives used was varied from 0 – 10 %w/w. The central composite design (CDD) was employed to experimentally design the formulation of GRE pipes. The photodegradation of the GRE pipes was performed by an outdoor exposure and simulated condition in Q-UV Lamp. The progress of photodegradation was followed by determining the changes in mechanical properties, physical properties and appearance, as a function of exposure time. The results showed that the GRE pipes containing 2, 1,3, and 10% w/w of UV-absorber, antioxidant, carbon black, and flame retardant, respectively had better mechanical properties than the others over period of exposure time. Similar results were observed in both outdoor and accelerated tests. In addition, it was found that UV exposure could actually improve short-term mechanical properties due to postcuring phenomenon. Under the accelerated condition, it was found that upon increasing the Q-UV exposure time, the physical properties in terms of the density, color, and gloss were decreased. Color changes involved initial fading followed by subsequent increased level of yellowing. The decrease in density and gloss values were attributed to the surface degradation induced by UV-irradiation. As evidenced by SEM micrographs, a substantial degree of catering and cracking was observed, especially after 10 years of Q-UV exposure.