No abstract

In this study, the mechanical properties and physical–chemical characteristics of curaua composites were evaluated using tensile and short beam testing and dynamic mechanical analysis. Curaua/polyester composites with different pretreatment (washing and drying), fiber length (10–50 mm) and fiber volume fraction (%Vf) (11, 22, and 38 vol%) were studied. The results show that the composites produced using 50 mm long washed/dried fibers and %Vf of 38 vol% achieved better mechanical properties, such as tensile strength and modulus and short beam strength. Fragility index “m” of the composites increased upon curaua incorporation, which may be attributed to a reduction in polyester chemical interactions (due to fiber dwelling of the polyester network). The energy required in initiating the cooperative motion at the “ideal” glass transition temperature and the cooperative rearrangement regions (CRR) also increased upon curaua incorporation, since CRR is considered the subsystem of the sample and for higher fiber content the greater the molecular heterogeneity. Finally, the Angell fragility concept was successfully applied to polymer composite systems. POLYM. COMPOS., 35:1078–1086, 2014. © 2013 Society of Plastics Engineers

In this study, we aimed to evaluate the characteristics of curaua composites using dynamic mechanical analysis. Curaua composites with distinct fiber volume fractions (11–38%) were studied, and their storage and loss moduli were found to increase with reinforcement content. On the other hand, the activation energy of the relaxation process in the glass‐transition region decreased with the curaua content; this conclusion was corroborated by the elastic chain concentration results. The Cole–Cole plots became flattened as the curaua content increased; this was indicative of a more homogeneous system, and the tan δ peak height and peak width at half‐height decreased. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012