Dynamic Mechanical Analysis (DMA) of Polymeric Composite Materials

Abstract

ResumoMateriais compósitos poliméricos vem sendo estudados nas mais diversas áreas da ciência dos materiais com o objetivo de substituir outros tipos de matérias-primas e melhorar o desempenho na sua aplicação. Dentre as diversas técnicas existentes, a análise dinâmico-mecânica (DMA) tem-se mostrado uma boa alternativa para avaliar as propriedades destes compósitos, em especial os parâmetros viscoelásticos em função do tempo, temperatura ou frequência. Propriedades importantes como como módulos de armazenamento e perda, e temperaturas de transição podem ser obtidas através desta técnica. O presente artigo traz uma revisão a respeito da técnica de DMA, suas vantagens em relação a outras análises térmicas e mecânicas, o comportamento de materiais compósitos poliméricos durante a análise e os parâmetros que podem ser estudados por ela. A importância da análise no estudo de materiais de engenharia também é relatado, em especial em aplicações aeroespaciais. Palavras-chaveCompósitos poliméricos; análise dinâmico-mecânica (DMA); materiais de engenharia; compósitos estruturais. Dynamic Mechanical Analysis (DMA) of Polymeric Composite Materials AbstractPolymeric composite materials have been studied in many fields in materials science, with the aim of replacing other materials and reaching better performance when applied. Among the existing techniques, a great alternative to evaluate composites properties is dynamic mechanical analysis (DMA), especially when viscoelastic parameters need to be studied as a function of time, temperature or frequency.Important properties, such as storage modulus, loss modulus and transitions temperaturescan be determined by this technique. The present paper brings a review about DMA, the advantages of this technique compared to others thermal and mechanical analysis, the behavior of polymeric composite materials during the tests and the properties which can be determined by DMA. The importance of DMA in the study of engineering materialsis also presented, especially when applied in aircraft structures.

Efeito De Diferentes Misturas Pp-Reciclado / Pp-Virgem Em Suas Propriedades Mecânicas

“…The storage modulus indicates the elastic response of the material, so the larger the E' the greater its elastic modulus (SANGRONIZ et al, 2018). Usually, polymeric materials present viscoelastic characteristics, and the increase of E' can indicate higher interactions and strong adhesion at the interfaces (LORANDI et al, 2016). In literature it was found that at ambient temperature, about 25 and 43°C (BHATTACHARJEE and BAJWA, 2018), the storage modulus of polymers and composites are similar, with values equal for composites 2 and 3 (Table 1).…”

Cellulose acetate obtained from Schizolobium parahyba (vell.) blake wood

“…The temperature variation in relation to the amount of energy dissipated by the material is called the loss module, being the region of viscous behavior. The delta tangent, or loss factor (Tan δ), is the ratio between the storage module and the loss module and allows to evaluate the molecular movements of the material according to the temperature variation (Callister, 2008;Lorandi, Cioffi & Ornaghi Junior, 2016). Figure 5 shows the transitions from the heating of the cellulose acetate membranes, in which it is possible to identify a change, in this study called β, due to the relaxation of the side groups and movements of small segments of the polymeric chain containing at least four atoms of carbon (Feng & Guo, 2016).…”

“…The glass transition temperature (Tg) is the temperature at which the polymer chains begin to move on a large scale (Hall, 1989) related to the rotational movements of the amorphous phase (Lorandi et al, 2016), in the case of a second order transition. Several studies consider that Tg corresponds to the highest value of the loss factor (Tan δ) (Akay, 1993;Rezaei, Yunus & Ibrahim, 2009;Niedermann, Szebényi & Toldy, 2015), others define it by the maximum value of the loss module (Murugan, Ramesh & Padmanabhan, 2014;Costa, Paiva, Botelho & Rezende, 2003), or due to the temperature at which there is a more marked change in the storage module (Lorandi et al, 2016). Akay et al (1993) report that the maximum point of the loss factor occurs at the end of the glass transition region, while the maximum point of the loss module occurs at its midpoint.…”