Yekta Karaduman

Mechanical Characterization of Carpet Waste Natural Fiber-reinforced Polymer Composites

This investigation deals with the property characterization of polymeric composites from abundantly available and renewable jute fibers. The aim of this article is to explore the possibility of using carpet waste jute yarn for value added fiber-reinforced composite materials and to investigate the physical and mechanical properties of these low-cost composites. Jute yarn was treated with 25 wt% NaOH solution to improve fiber—matrix interface. NaOH-treated jute yarn was crimpier, bulkier, more hairy, and flexible. The investigation of the mechanical properties of composites was performed as a function of yarn type, reinforcement form, matrix type, alkali treatment, and fiber content. For this purpose, the tensile, flexural and charpy impact tests were performed. It was found that composite samples from alkali treated reinforcement had better mechanical properties based on the investigated parameters. SEM analyses showed that alkali treatment improves bonding across the fiber—matrix interface. Jute—epoxy composites showed better tensile and flexural strength in comparison to jute—polyester composites, whereas impact strength of epoxy matrix composites were almost half that of polyester matrix composites. Composites from double ply jute yarns showed better flexural strength. Taking into account the reinforcement form, jute composites from random reinforcement form showed higher tensile strength and modulus. The study strongly suggests that the jute fiber waste-reinforced polymer composite materials are quite capable to serve as a potential cost effective, technologically viable, and attractive substitute to the conventional glass fiber composites.

Water absorption behavior of carpet waste jute-reinforced polymer composites:

This article deals with the water absorption behavior of low-cost polymer composite composed of carpet waste jute yarns and thermoset matrices (i.e., epoxy and polyester). The water absorption behavior of the composites and deviation of their flexural and impact properties after aging in distilled water were investigated. The magnitude of diffusion parameters such as n and K were evaluated to assess the mode of water transport. It was found that the composites follow Fickian diffusion behavior. Both maximum water content (Mmax) and effective diffusion coefficient (Deff) values increased with increasing fiber content. Epoxy matrix composites showed higher Mmax and D eff values when compared to those of polyester matrix composites. D eff value increased remarkably with an increase in immersion temperature, whereas temperature had relatively little impact on Mmax value. Thermodynamics of diffusion process was investigated using Arrhenius plots and the magnitude of the activation energy for the process of diffusion (E a) was evaluated. Ea increased with temperature increment, suggesting fast access of water into polymer segments at elevated immersion temperatures. NaOH treatment of jute yarns was also investigated in terms of the water absorption behavior of the composites. It was shown that alkali treatment reduces water absorption of the composites remarkably, which was attributed to interface improvement. Flexural strength and modulus of the composites decreased up to 40% and 60%, respectively, whereas Charpy impact strength increased up to 30% after 168 h of water immersion.

Dynamic mechanical and thermal properties of enzyme-treated jute/polyester composites

Dynamic mechanical and thermal behavior of polyester composites reinforced with enzyme and NaOH-treated jute woven fabrics were studied. Dynamic properties such as storage modulus (E′), loss modulus (E″) and damping parameter (tan δ) were determined in a single-cantilever bending mode. The storage modulus of the composites increased up to 110% and 130% with enzymatic and NaOH treatments, respectively. The composites reinforced with NaOH and enzyme-treated fibers showed a shift in loss modulus to a higher region when compared to untreated fiber composites. This was attributed to the increased immobilization of polymer matrix at the fiber–matrix interface as a result of pre-treatments. Tan δ pick values of the samples with treated and untreated jute fibers are fairly close indicating that all the samples showed very similar energy damping behavior. The derivative thermogravimetric and differential scanning calorimetry curves indicated that the thermal stability of the composites slightly decreased in the case of NaOH and enzyme treatments. Scanning electron microscopy pictures revealed a stronger fiber–matrix adhesion in composites with enzyme-treated fibers when compared to untreated fiber composites.

Experimental Investigation on the Flexural and Dynamic Mechanical Properties of Jute Fiber/Cork-reinforced Polyester Sandwich Composites

The flexural and dynamic mechanical behavior were evaluated for a new jute woven fabric/cork-reinforced polyester sandwich composite. To improve the fiber/matrix adhesion, jute fibers were treated with sodium hydroxide (NaOH) and silane prior to composite preparation. The results indicated that the flexural strength and modulus of the composites increased after the alkali and alkali + silane treatments. Similarly, dynamic mechanical parameters, such as storage and loss modulus of the sandwiches, were enhanced as a result of alkali and silane treatments due to a better fiber/matrix adhesion compared with the untreated composites. It was also shown that the damping parameter decreased after the interfacial treatments, which indicated that the energy damping efficiency decreased as the interface quality was improved.