Optimisation of Mechanical Properties in Saw-Dust/Woven-Jute Fibre/Polyester Structural Composites under Liquid Nitrogen Environment Using Response Surface Methodology.

Velmurugan Ganesan,Yoganandam Krishnamoorthy,Vasudevan Alagumalai,Seyed Mohammad Javad Razavi,Michael Försth,Suresh Kumar Shanmugam,Sekar Sanjeevi,Gabriel Sas,Vigneshwaran Shanmugam,Babu Kaliyamoorthy,Oisik Das

doi:10.3390/polym13152471

Abstract

Natural fibre-based composites are replacing traditional materials in a wide range of structural applications that are used in different environments. Natural fibres suffer from thermal shocks, which affects the use of these composites in cold environment. Considering these, a goal was set in the present research to investigate the impact of cryogenic conditions on natural fibre composites. Composites were developed using polyester as matrix and jute-fibre and waste Teak saw-dust as reinforcement and filler, respectively. The effects of six parameters, viz., density of saw-dust, weight ratio of saw-dust, grade of woven-jute, number of jute layers, duration of cryogenic treatment of composite and duration of alkaline treatment of fibres on the mechanical properties of the composite was evaluated with an objective to maximise hardness, tensile, impact and flexural strengths. Taguchi method was used to design the experiments and response-surface methodology was used to model, predict and plot interactive surface plots. Results indicated that the duration of cryogenic treatment had a significant effect on mechanical properties, which was better only up to 60 min. The models were found to be statistically significant. The study concluded that saw-dust of density 300 kg/m3 used as a filler with a weight ratio of 13 wt.% and a reinforcement of a single layer of woven-jute-fibre mat of grade 250 gsm subjected to alkaline treatment for 4 h in a composite that has undergone 45 min of cryogenic treatment presented an improvement of 64% in impact strength, ca. 21% in flexural strength, ca. 158% in tensile strength and ca. 28% in hardness.

Highlights

Growing concerns for the environment have accelerated the replacement of synthetic composites and plastics with natural fibre composites (NFC), which potentially have lower carbon footprint
With the continued increase of the cryogenic treatment time, cracks developed at secluded regions because the fibres, saw-dust and the matrix constricted at different rates [26], Figure 4c
Saw-dust of density 300 kg/m3 used as a filler with a weight ratio of 13% and a reinforcement of a single layer of woven-jute-fibre mat of grade 250 gsm subjected to alkaline treatment for 4 h in a composite that has undergone 45 min of cryogenic treatment delivers an impact strength of 3.3375 kJ/m2, flexural strength of 44.9604 MPa, tensile strength of 33.4353 MPa and hardness of 51.4875 BHN

Summary

Introduction

Growing concerns for the environment have accelerated the replacement of synthetic composites and plastics with natural fibre composites (NFC), which potentially have lower carbon footprint. Natural fibre-based composites have been found in structural applications. The use of jute-based natural fibre composites in structural applications is recommended due to the improved strain behaviour and fatigue strength [1]. Structural composites are used in extremely cold weather In these circumstances, the temperature variation causes high thermal stress in materials, which lead to failure [3]. Natural fibres’ hydrophilic nature (i.e., higher volume of ice than that of water) causes poor load transfer and unexpected failure in cold environments. To avoid such a failure, the composite strength must be increased to withstand thermal stress under cryogenic conditions [4]. Hybridisation and chemical treatment of natural fibres are the notable methods that are in practice to increase the strength of such composites

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Conclusion