Effects of Moisture on Dynamic Mechanical Properties of Wood Fiber Composites Studied by Dynamic FT-IR Spectroscopy

Abstract

Wood fiber reinforced polylactide is a biodegradable composite where both fibers and matrix are from renewable resources. In the development of such new materials, information on mechanical behavior on the macroscopic and the molecular level is useful. In this study, dynamic Fourier transform infrared (FT-IR) spectroscopy is used to measure losses at the molecular level during cyclic tensile loading for bonds that are characteristic of the cellulosic fibers and the polylactid matrix. This molecular behavior is compared with measured macroscopic hysteresis losses for different moisture levels. The results show that moisture ingress will transfer the load from the fibers to the matrix, and that a more efficient fiber-matrix interface would diminish mechanical losses. Although the dynamic FT-IR spectroscopy method is still qualitative, this investigation shows that it can provide information on the stress transfer of the constituents in wood fiber reinforced plastics.

Formulation-properties versatility of wood fiber biocomposites based on polylactide and polylactide/thermoplastic starch blends

“…It was proved that the moisture or water absorption decreased substantially the mechanical properties. A possible explanation is that moisture makes the interfacial stress transfer less efficient when is adsorbed at the interface, and as a consequence, a larger part of the load will be carried by the brittle PLA matrix only .…”

An experimental set-up for real-time continuous moisture measurements of plywood exposed to outdoor climate

“…extensively [11], [12], [13], [14], [15] and [16]. For plywood far less research has been carried out, yet this is critical regarding the Construction Products Directive (CPD; [17]) as from which emanates the need for research in the field of service life prediction and planning as to satisfy the requirements for Annex I [18].…”

Damping behavior of plant fiber composites: A review

“…PFCs are not only affected by the matrix when dealing with wet environment compared to SFCs, but the changes in fiber molecules also need to be understood. The dynamic FT-IR technique can be used since the traditional macro-mechanical tests cannot provide information about the stress transfer between the fiber and the matrix [190]. As moisture is transported from the plant fibers to the interface between fiber and matrix, the ability to transfer stress between the fibers and the matrix is reduced [190].…”