Browsing by Author "Al-Huniti, N."

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Critical review of the factors dominating the fracture toughness of CNT reinforced polymer composites
(IOP Publishing, 2019-01) Al-Maharma, Ahmad Yousef Mohammad; Şendur, Polat; Al-Huniti, N.; Mechanical Engineering; ŞENDUR, Polat; Al-Maharma, Ahmad Yousef Mohammad
In this study, the main factors, which have substantial influence on fracture toughness of carbon nanotubes (CNTs)-based composites both at nano and macro scales, are discussed in detail. Based on the findings from the reviewed literature, the improvement obtained on fracture toughness of CNTs multi-scale composites are due to the effect of CNTs on crack bridging and pullout toughening mechanisms. It is highly recommended to reinforce raw composites with low content of CNTs in order to improve the dispersion and interfacial adhesion of CNTs with surrounding polymer. Long aligned MWCNTs with small diameters (high aspect ratio) are recommended to be used to reinforce FRP composite in order to obtain superior fracture resistance toward initiated cracks. We found out that the factors, which govern the fracture toughness in multi-scale composites, are strongly correlated to each other. The most critical factors that affect the fracture toughness include the alignment and structure (length of nanotube) followed by the type of functionalization conducted on the surface of CNTs.
Open Access
Critical review of the parameters affecting the effectiveness of moisture absorption treatments used for natural composites
(MDPI AG,, 2019) Al-Maharma, Ahmad Yousef Mohammad; Al-Huniti, N.; Al-Maharma, Ahmad Yousef Mohammad
Natural composites can be fabricated through reinforcing either synthetic or bio-based polymers with hydrophilic natural fibers. Ultimate moisture absorption resistance at the fiber–matrix interface can be achieved when hydrophilic natural fibers are used to reinforce biopolymers due to the high degree of compatibility between them. However, the cost of biopolymers is several times higher than that of their synthetic counterparts, which hinders their dissemination in various industries. In order to produce economically feasible natural composites, synthetic resins are frequently reinforced with hydrophilic fibers, which increases the incompatibility issues such as the creation of voids and delamination at fiber–matrix interfaces. Therefore, applying chemical and/or physical treatments to eliminate the aforementioned drawbacks is of primary importance. However, it is demonstrated through this review study that these treatments do not guarantee a sufficient improvement of the moisture absorption properties of natural composites, and the moisture treatments should be applied under the consideration of the following parameters: (i) type of hosting matrix; (ii) type of natural fiber; (iii) loading of natural fiber; (iv) the hybridization of natural fibers with mineral/synthetic counterparts; (v) implantation of nanofillers. Complete discussion about each of these parameters is developed through this study.