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56 PCB007 MAGAZINE I MARCH 2022 modulus, the yield strength, and the ultimate tensile strength. Laboratory instruments are used to assess these responses, otherwise known as viscoelastic properties, under conditions of low mechanical force. Controlled heating and cooling are incorporated to study temperature effects on polymer stiffness and resiliency. Method of Assessment In this evaluation, we used dynamic mechan- ical analysis (DMA) to study and characterize storage modulus (E'), loss modulus (E"), and loss factor tan (delta) as a function of temper- ature. is is all captured by applying the glass transition temperature of resin composites. From the elastic and storage modulus, we can calculate tan delta—ratio of G" to G'—show- ing the relative degree of damping of the mate- rial. is is an indicator of the material's effi- ciency in preventing energy loss from molecu- lar rearrangements and internal friction. Tan- gent of delta, or tan delta, quantifies the way in which a material absorbs and disperses energy. It expresses the out-of-phase time relationship between an impact force and the resultant force transmitted to the supporting body, whereas loss modulus and storage modulus are attributes to the given tan delta. We selected and evaluated three known TUC resin composites that are predominantly in HSD designs and applications. Observation Due to customer requests, we did numer- ous sequential laminations and measured tan delta aer each thermal lamination exposure. e data indicates that all three resin com- posites meet their design requirements. We did observe an initial drop in tan delta during the second lamination cycle on T2Sp, but the T2Sp did not reach a fatigue outcome over- all, thus avoiding premature fatigue. Even aer doing up to 10 sequential thermal laminations, the data showed no significant spread between the sixth and 10th cycles in terms of tan delta, indicating that all three resin composites can endure multi-lamination cycles, as shown in Figures 1 and 2 with eight and 10 sequential cycles. e data for all three resin composites was compiled using DMA shi and tan delta drop. Tg is a function of heating/cooling rate. We measured energy dissipation through loss modulus to determine the hardness and stiff- ness of the composites during sequential lam- ination cycles. e data suggest that there is a

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