8.4 Effects of a Crosslinking Gradient on Material Properties of a Thin Film
(Room 234-236)
10 Apr 18
11:00 AM
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11:30 AM
Tracks:
Session 8: Measuring & Testing, Session 8: Measuring & Testing I
Quantitative information regarding the degree of polymerization of thin films with ultraviolet light is crucial to estimate material properties. SR-399 (dipentaerythritol pentaacrylate) is a multifunctional, fast cure, low skin irritant monomer with abrasion resistance and good flexibility. Photopolymerization from one surface of a film creates a gradient through the part. Confocal Raman microspectroscopy can measure carbon-carbon double bond consumption, leading to estimate the degree of crosslinking. The carbon-carbon double bond composition is expected to be a function of film depth, light intensity, and photoinitiator concentration. Mechanical properties can be obtained from nanoindentation measurements along the film depth. Preliminary nanoindentation experiments have confirmed the presence of a crosslinking gradient, due to deviations in the Young’s modulus, as a function of film depth and ultraviolet light intensity. This is one of the first studies linking thin film polymeric morphology to physical performance, which is crucial when applying the technology for part synthesis.