Evaluating the performance of gamma irradiated okra fiber reinforced polypropylene (PP) composites: comparative study with jute/PP

A. N. M. Masudur Rahman,Ruhul A. Khan,Shah Alimuzzaman,Jamal Hossen

doi:10.1186/s40691-018-0148-y

Abstract

In this study, two bast fibers such as okra and jute were selected to manufacture composites taking polypropylene (PP) as matrix material by means of compression molding technique with maintaining 40% fiber content on the total weight of the composites. Investigation was done on tensile properties such as tensile strength (TS), tensile modulus (TM), elongation at break (EB%), bending properties such as bending strength (BS), bending modulus (BM) and impact properties like impact strength (IS) and hardness (Shore-A) of the composites. From analyzed data, it was found that Okra/PP composites showed very competitive mechanical properties to Jute/PP composites. Non-irradiated okra composite showed the value of TS, TM, BS, BM, IS and hardness to be 32.2 MPa, 602 MPa, 55.6 MPa, 3.6 GPa, 19.54 kJ/m2 and 95 (Shore-A), respectively, whereas that value for non-irradiated jute composite was 35.5 MPa, 629 MPa, 71.5 MPa, 4.5 GPa, 21.48 kJ/m2 and 96 (Shore-A), respectively. The composite samples were exposed to different intensities of gamma radiation (250‒1000 krad) at a dose rate of 330 krad/h and changes in mechanical properties were examined. Both irradiated composites (500 krad) showed significant improvement of mechanical properties compared to that of the non-irradiated composites. Maximum TS, TM, BS, BM and IS value were found to be 41.9 MPa, 685 MPa, 72 MPa, 4.7 GPa and 22.6 kJ/m2, respectively for irradiated okra composite and 45.3 MPa, 717 MPa, 88 MPa, 6.7 GPa and 24.3 kJ/m2, respectively for irradiated jute composite. Fourier transform infrared spectroscopy was used to identify the surface groups of the composites. Water absorption, degradation behavior of the composites under soil and heat medium were also performed. Degradation tests revealed that okra composite retained its original mechanical properties higher than that of jute composite. The morphology of the composites was inspected by scanning electron microscope.

Highlights

IntroductionNowadays polymer composites are widely used in different diversified fields because of their excellent and unique combination of physical and mechanical properties and they are extensively using in the civil constructions, chemical equipment and machinery constructions, electrical and electronic equipment, automobile and marine industries, aircraft manufacturing and many more (Islam et al 2009; Jawaid et al 2011; John and Naidu 2004; Karina et al 2008; Khalil et al 2007; Khan et al 2009; Rajulu and Devi 2007; Saba et al 2015)
It was examined that okra composites showed comparatively lower tensile, bending and impact strength but better water resistant properties than jute composite
Gamma radiation was applied on composites with the dose variation from 250‒1000 krad at a dose rate of 330 krad/h

Summary

Introduction

Nowadays polymer composites are widely used in different diversified fields because of their excellent and unique combination of physical and mechanical properties and they are extensively using in the civil constructions, chemical equipment and machinery constructions, electrical and electronic equipment, automobile and marine industries, aircraft manufacturing and many more (Islam et al 2009; Jawaid et al 2011; John and Naidu 2004; Karina et al 2008; Khalil et al 2007; Khan et al 2009; Rajulu and Devi 2007; Saba et al 2015). Synthetic fiber reinforced thermoplastic composites are dominating over natural fiber reinforced composites due to their improved strength, stability, corrosion and moisture resistance properties. Due to increasing environmental consciousness, composites made of lingo-cellulosic materials as reinforcing fiber and thermoplastic polymers as matrices are exploring day by day (Rahman et al 2008). Among all the natural fibers, jute has appealed worldwide attention as a potential reinforcement of polymer composite because of its inherent properties such as high tensile strength, low density, inexpensive and abundantly available in tropical countries (Haydaruzzaman et al 2010; Islam et al 2009; Khan et al 1999). The mucilage of okra fiber can be applicable for the production of decomposable polymer materials with proper grafting process (Mishra and Pal 2007). The fiber exhibited improved tenacity (40.1–60.5 MPa) and higher elongation at break (3–5%) (Alam and Khan 2007; Khan et al 2009a)

Methods

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Discussion

Conclusion