Fabrication and Mechanical Performance of Non-Crimp Unidirectional Jute-Yarn Preform-Based Composites

This work developed novel jute-yarn, non-crimp, unidirectional (UD) preforms and their composites, with three different types of warp jute yarns of varying linear densities and twists in the dry UD preforms, in order to present a possible solution to the detrimental effects of higher yarn twists and crimp at the warp–weft yarn interlacements of traditional, woven, preform-based composites on their mechanical properties. In the developed UD preforms, warp jute yarns were placed in parallel by using a wooden picture-frame pin board, with the minimal number of glass weft yarns to avoid crimp at the warp–weft yarns interlacements, which can significantly enhance the load-bearing ability of UD composites compared to traditional, woven, preform composites. It was found that an optimal combination of jute warp yarn linear densities and twists in the UD preforms is important to achieve the best possible mechanical properties of newly developed UD composites, because it encourages a proper polymer-matrix impregnation on jute fibres, leading to excellent fibre–matrix interface bonding. Composites made from the 25 lb/spindle jute warp yarn linear density (UD25) exhibited higher tensile and flexural properties than other UD composites (UD20, UD30). All the UD composites showed a much better performance compared to the traditional woven preform composites (W20), which were obviously related to the higher crimp and yarn interlacements, less load-carrying capacity, and poor fiber–matrix interfaces of W20 composites. UD25 composites exhibited a significant enhancement in tensile modulus by ~232% and strength by ~146%; flexural modulus by 138.5% and strength by 145% compared to W20 composites. This reveals that newly developed, non-crimp, UD preform composites can effectively replace the traditional woven composites in lightweight, load-bearing, complex-shaped composite applications, and hence, this warrants further investigations of the developed composites, especially on long-term and dynamic-loading mechanical characterizations.

Effects of Microwave Treatment in Immersed Conditions on the Mechanical Properties of Jute Yarn

The versatile bast fiber jute has environmental benefits compared to glass fibers. However, for jute to be used in a composite, the fiber properties need to be altered. This study aims to improve the mechanical properties of jute yarn to make it more suitable for technical applications as a composite. To alter its mechanical properties, jute yarn was immersed in water during microwave treatment. The time and power of the microwave settings differed between runs. Two states of the yarn were tested: fastened and un-fastened. Tensile testing was used at the yarn and fiber level, followed by Fourier-transform infrared spectroscopy (FTIR) and microscopy. The treatment result demonstrated the ability to increase the elongation of the jute yarn by 70%. The tenacity was also increased by 34% in the fastened state and 20% in the un-fastened state. FTIR showed that no change in the molecular structure occurred. The treatments resulted in a change of yarn thickness depending on the state of the yarn. The results indicate that microwave treatment can be used to make jute more suitable for technical applications depending on the microwave treatment parameters.

Structural Performance of Chemically Modified Natural Jute Yarn for Strength Demanding Composite Applications

Manufacturing natural based high-performance composites is becoming a greater interest to the composite manufacturers and to their end users due to their bio-degredability,low cost and availability. Yarn based textile architecture is commonly used in manufacturing these composites due to their excellent formability. However, for using natural based yarn as a reinforcing architectures in high load bearing structural composite applications, a significant improvement in mechanical performance is required. Particularly, jute fibre yarn suffers with poor mechanical properties due to the presence of fibrillar network, polysacharides and other impurities in the fibre. For achieving this, we use aqueous glycine treatment (10%, W/V) on alkali(0.5 %, W/V) and untreated jute yarns for the first time. The glycine treatment on alkali treated jute yarns (ATG) shows a huge improvement in tensile strength and strain values by almost ⁓105% and ⁓50 % respectively compared to untreated jute yarns (UT) because of the strong interactions and bonds developed between glycine, alkali and jute yarns. It is believed that the newly developed glycine treated jute yarns will be helpful to promote jute yarns in composite industries where load-bearing is primary requirement and replace their synthetic counterparts.

Sorption Isotherms and Thermodynamics of Direct Dye onto the Nano Poly(amidoamine) Dendrimer Treated Jute Yarn

Background: In this study, the poly(amidoamine) (PAMAM) G-2 dendrimer was applied to the jute yarn. Methods: Untreated and dendrimer treated jute yarns were then dyed with Direct Yellow 24. Thermodynamic parameters of dyed samples, free energy (ΔG°), the enthalpy (ΔH°), and the entropy (ΔS°) were also evaluated. Results: Dendrimer treated jute yarn showed higher dye sorption compare to untreated jute yarn. The values of ΔH° and ΔG° indicated that the sorption process was exothermic and spontaneous at low temperature. Conclusion: Freundlich isotherm was found to be the optimum isotherm for untreated and BET isotherm defined for dendrimer treated jute yarn.

Improving Dyeing Properties of Jute Yarn to Metal Complex Dyes via Grafting with Methyl Methacrylate and Using Nano Silver

Objective: In this study, bleached jute yarn was treated with methyl methacrylate and then in situ synthesis of silver nanoparticles were performed. Experimental: Experimental data showed a decrease in tensile strength of treated yarns from 0.91 to 0.78 g/dtex. Afterwards, treated samples were dyed with 1:1 and 1:2 pre-metallised dyes. Results: Methyl methacrylate treated jute yarns exhibited higher color strength (12.55%) and fastness properties as compared to untreated samples. Conclusion: Methyl methacrylate treated and nano-coated jute yarns showed much better color strength (23.96%) and higher color fastness properties towards light and washing.