BS in Materials Engineering
Materials Engineering Department
Two different two-component resin systems were cured, via Differential Scanning Calorimetry, for the times recommended by their respective manufacturers. The resin cure schedules were designed to simulate typical and attainable processing conditions; they were cured at 120°F, 140°F, and 160°F, and in-mold post-cured at 200°F, 230°F, and 260°F. The resulting scans were then compared to a baseline cure for each resin system, consisting of two heating-cooling cycles at a constant rate of temperature change. These baseline cures were then used to determine the percent cure of each sample and the shift in glass transition temperature between the baseline cure and the samples. Analysis showed that all samples were fully (100%) cured. This was confirmed by producing partially cured samples for each resin system, which all used a lower curing temperature than the regular samples. The first resin system displayed 91.8% cure with a curing temperature of 167°F, while the second system showed 92.1% cure at a curing temperature of 150°F. Statistical analysis showed that there was no significant effect of cure temperature or in-mold post-curing temperature on the shift in glass transition temperature of the resin, nor was there any significant interaction between the two factors. The glass transition temperature of resin A was 154.5°F with a standard deviation of 13.9°F, while the glass transition temperature for resin B was 164.4°F with a standard deviation of 22.0°F. Tensile samples were made using the same processing temperatures, but were also thoroughly mixed and degassed to reduce porosity once the resin was poured into the mold. The samples were then tested and analyzed based on tensile strength; the average tensile strength of the resin A samples was 60.44 MPa with a standard deviation of 2.40 MPa, and the average tensile strength of the resin B samples was 63.19 MPa with a standard deviation of 5.87 MPa. It was discovered that the cure schedule did not have a statistically significant effect on the tensile strength of the resin.