Mechanical Properties of Weathered Facial Elastomers Containing Glass Pigments

Objective: Previously yellow glass-based pigments demonstrated improved color stability in weathered elastomers (AADR 2010 #724). This study assessed tensile properties of elastomers colored with intrinsic, extrinsic and glass pigments. Methods: 10 wt% red, yellow, violet or tan pigments were mixed into vinyl-terminated PDMS containing 13 wt% silica filler. Each mixture was combined with equimolar polymethyl hydrogen siloxane crosslinker and materials were polymerized into dumbbells (ASTM D412, n=20). 3000 h weathering challenges included UVB (0.72 J/cm²/h), heat (65C), humidity (80% r.h.) and control (darkness, 25C, 30% r.h.). Uniaxial tensile tests at 500 mm/min with extensometer measured strength (UTS), breaking strain (BS) and Young's modulus between 50-100% strain (M). Tensile property differences were compared according to color, pigment type and weathering exposure (ANOVA/Tukey, p≤0.01). Results:  UVB- UTS(MPa): Color- red(1.12)^a yellow(1.08)^a violet(0.96)^b tan(0.86)^b. Type- glass(1.22)^a extrinsic(1.00)^b intrinsic(0.82)^c.  BS(%): Color- violet(190)^a tan(162)^b red(150)^b yellow(137)^c. Type- extrinsic(182)^a intrinsic(171)^a glass(132)^b.  M(MPa): Color- yellow(0.74)^a red(0.70)^a tan(0.47)^b violet(0.42)^b. Type- glass(0.87)^a extrinsic(0.47)^b intrinsic(0.40)^b. Heat- UTS(MPa): Color- yellow(1.18)^a tan(1.02)^b red(1.02)^b violet(0.91)^b. Type- glass(1.15)^a extrinsic(1.09)^a intrinsic(0.87)^b.  BS(%): Color- red(200)^a yellow(167)^b violet(155)^bc tan(146)^c. Type- intrinsic(193)^a extrinsic(168)^b glass(141)^c.  M(MPa): tan(0.61)^a yellow(0.59)^a violet(0.51)^b red(0.46)^c.  Humidity- UTS(MPa): Color- yellow(1.18)^a red(0.98)^b tan(0.96)^b violet(0.90)^b. Type- glass(1.11)^a extrinsic(1.01)^ab intrinsic(0.91)^b.  BS(%): Color- violet(207)^a red(194)^ab tan(184)^ab yellow(175)^b. Type- extrinsic(214)^a intrinsic(194)^b glass(162)^c.  M(MPa): yellow(0.56)^a red(0.44)^ab tan(0.44)^ab violet(0.36)^b.  Type- glass(0.60)^a extrinsic (0.38)^b intrinsic(0.37)^b. Control- UTS(MPa): Color- tan(1.1)^a violet(1.03)^ab red(0.99)^b yellow(0.99)^b. Type- glass(1.17)^a extrinsic(1.02)^b intrinsic(0.90)^c.  BS(%): Color- violet(222)^a tan(205)^a red(147)^b yellow(130)^b.  Type- extrinsic(197)^a intrinsic(169)^b glass(161)^b.  M(MPa): Color- yellow(0.70)^a red(0.63)^b tan(0.45)^c violet(0.38)^d.  Type- glass(0.71)^a extrinsic(0.46)^b intrinsic(0.45)^b.  Conclusions: Generally UVB acted to increase UTS and M while reducing BS.  Humidity tended to increase BS and decrease M.  Heat decreased M.  Glasses commonly produced materials with higher UTS, M and lower BS.   Supported by VA Rehabilitation R&D grant A4290I.