In situ monitoring of moisture uptake of flax fiber reinforced composites under humid/dry conditions

Abstract

The use of green materials such as natural fiber‐reinforced composites represents an increasingly stringent prerogative in the future planning of industrial and non‐industrial production. The optimization of these materials is the main aim of the current research, focused on the evaluation of the behavior of flax fiber reinforced composites exposed to isothermal adsorption and desorption cycles, at varying the partial pressure of water vapor (P/P0). For this purpose, the moisture uptake and the morphology changes of the composite material and their constituents were in situ monitored through a measurement protocol, by using a dynamic vapor sorption (DVS) analysis, coupled with an environmental scanning electron microscopy (ESEM) visual investigation. A dependence of moisture uptake and diffusivity on the composite morphology was clearly detected. In particular, no significant variation in the morphology of the specimen is noticed at low water vapor partial pressure (i.e., P/P0 up to 5.4%) due to the limited absorption capacity (i.e., lower than 1%). On the other hand, fibers morphology changes at increasing the partial pressure up to 25.1%, showing a sensitive increase in volume. This phenomenon becomes much more relevant for high relative humidity values (i.e., ~90%), reaching more than 6% of absorption capacity.

Investigation of Zalacca Midrib – Based Composites Fibers as Prosthetic Socket Materials Accounting for a Variety of Alkali and Microcrystalline Cellulose Treatment.

“…[58]. In another investigation using flax fiber and bioepoxy composites, a flexural strength of 90.2 MPa was achieved [59]. The flexural strength can be attributed to ZMF purification through alkali treatment, eliminating amorphous components such as hemicellulose, pectin, and lignin.…”

Functional Polymer Nanocomposites with Increased Anticorrosion Properties and Wear Resistance for Water Transport

“…To improve the properties of polymers, including those based on epoxy, plasticizers and fillers are introduced into the oligomer [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. It should be noted that the introduction of modifiers is promising, since such additives with a small content (1–5%) allow a significant increase in the indicators of adhesive and cohesive strength of epoxy composites [ 10 , 13 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. The latter, in turn, should be used in the form of matrices for protective coatings of working parts, including during their repair in voyage conditions of sea and river transport vessels.…”

“…The analysis of the direction of publications researching the properties of epoxy CMs indicates the need to introduce synthesized oxide or carbide fillers into the oligomer to obtain materials with increased operational characteristics. It is proven [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ] that the introduction of dispersed particles into the resin, even in small quantities, ensures a change in the speed of the course of the physicochemical processes during the structure formation of CM. Moreover, not only the chemical and physical nature but also the content and dispersion of the particles are important in regulating the crosslinking processes of epoxy CMs.…”

Online characterization of moisture transport in a high-performance carbon fiber-reinforced thermoplastic composite at high temperatures: Identification of diffusion kinetics

“…Moreover, the handling time outside the test environment can be a significant source of error. To overcome these limitations, another technique used in the literature is the Dynamic Vapor Sorption (DVS) method [30,31]. DVS instruments operate by flowing precisely controlled concentrations of water vapors in dry air over a sample at a known flow rate and temperature.…”