Abstract
A testing program was conducted to determine the suitability and reliability of adhesives and polycarbonate (pc) lenses for extended use in luminaires in mine environments. Polycarbonates were exposed, for periods up to 36 months, to four environments including ultraviolet light, humidity, intermittent water spray and heat of either 180 deg f or 240 deg f in various combinations. Izod impact tests on the exposed lens material indicated that polycarbonate functions well under all 180 deg f environments and could be used with confidence for periods exceeding the test period, for as long as 10 years, with a suitable safety factor employed in design. The specimens exposed at 240 deg f showed decreased toughness after 24 months' exposure. A 462-day compatibility test between polycarbonate and six hydraulic fluids was run on stressed pc beams. One fluid caused beam breakage in less than 1 day, while three caused breakage at intermediate times. Two fluids exhibited essentially no effect on the pc when compared with a control. Three epoxy combinations tested showed low and erratic failure stresses. A room-temperature-cure silicone adhesive functioned extremely well for the time periods up to 36 months and temperatures up to 240 deg f.
