Evaluation of Water Diffusion Mechanism on Mechanical Properties of Polypropylene Composites

Abstract

This study evaluates the water diffusion mechanism on mechanical properties of polypropylene reinforced composites. Compounding of the composites into sheets was carried out using the compression moulding techniques by incorporating varying weight percentage of fibers and polypropylene. Mechanical properties of the composites were assessed according to ASTM standards, while the composite fracture surface was examined using a scanning electron microscope. The water absorption behaviour and diffusion mechanisms on mechanical properties of fabricated composites were analysed using a water immersion test and the Fickian diffusion model. The results show that mechanical properties of all polypropylene reinforced composites under dry condition was higher than wet condition. The composites reinforced with 7 wt.% (KOH and NaOH) fibers follow a consistent trend and gave the highest tensile strength and tensile modulus in comparison with pure PP (polypropylene). Addition of fibers into the polypropylene matrix gradually decreases composites impact strength with exception to 3 wt.% and 5 wt.% composites. The hardness properties of reinforced composites were steadily increased as the fiber loading increases which signify strong fiber-matrix bonding. The percentage of water absorbed for all reinforced composites increased as the fiber weight increases and slowly flattened off after 10 days of saturation. The morphological study revealed fiber pullout and delamination of reinforced composites attributed to poor fiber-matrix adhesion amount to water intake. The diffusion transport mechanism of polypropylene composites was observed to obey the Fickian diffusion model.

Variations in the mechanical properties of bionanocomposites by water absorption

“…Similar type of observation of water diffusion was reported by Balogun et al. 34 On increasing the soaking time, epoxy and all the bionanocomposites obtained their saturation stage after 28 days of soaking time. It is very interesting to observe that all the bionanocomposites have very less water uptake (i.e.…”

“…Balogun et al. 34 observed that the tensile strength of Entada mannii fiber-reinforced polypropylene composites was significantly reduced compared to dry specimen by water uptake credited to an increase in fibers loading causing poor fiber–matrix interfacial bonding. In some other studies, a reduction in the tensile properties of biocomposites as a result of water uptake was also reported.…”

The Integral Utilization of Date Palm Waste to Produce Plastic Composites

“…As shown in Figure 10 , the behavior of the composite materials obtained does not conform to the Fickian diffusion mechanism curve but rather resembles a non-Fickian or anomalous behavior [ 74 ]. Table 6 shows the kinetic parameters slope and intercept, as well as the degree of linear correlation of the curve.…”

Water Absorption Behavior of Oil Palm Empty Fruit Bunch (OPEFB) and Oil Palm Kernel Shell (OPKS) as Fillers in Acrylic Thermoplastic Composites

“…However, acrylic thermoplastic composites, as well as other polymeric matrices reinforced with natural fibers, have drawbacks such as limited processing temperature, lack of compatibility between fiber and matrix, low fire resistance, and high water absorption [ 7 , 17 ]. The latter is a critical parameter in the performance of these composites, since water absorption usually produces poor adherence between the matrix and fibers, poor stress transfer, matrix degradation, and dimensional instability [ 21 , 22 , 23 ]. The water absorption in thermoplastic matrix composites reinforced with natural fibers is mainly related to the chemical composition and microstructure of natural fibers [ 21 ].…”