Sains Malaysiana 47(2)(2018): 367-376

http://dx.doi.org/10.17576/jsm-2018-4702-19

The Effect of Kenaf Filler Reinforcement on the Mechanical and Physical Properties of Injection Moulded Polypropylene Composites

(Kesan Penguatan Pengisi Kenaf ke atas Sifat Mekanik dan Fizikal Pengacuan Suntikan Komposit Polipropilena)

Mohd Khairul Fadzly Md Radzi¹*, Norhamidi Muhamad¹, Majid Niaz Akhtar², Zakaria Razak¹ & Farhana Mohd Foudzi¹

¹Department of Mechanical & Materials Engineering, Faculty of Engineering & Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

²Department of Physics, COMSATS Institute of Information Technology, 54000 Lahore, Pakistan

Received: 8 June 2017/Accepted: 18 August 2017

ABSTRACT

Natural fibres potentially offer better reinforcement to improve the mechanical and physical properties of polymer composites. However, these natural materials at this stage are not fully explored yet due to the fibres themselves have limited heat resistance and are quite sensitive to moisture. This limitation will weaken the adhesion when interacting with thermoplastic matrices during the processing of composites. Therefore, the main purpose of this study is to investigate inherent strength characteristics among kenaf (core and bast) fillers as a reinforcement in polypropylene composites at various geometries and loadings via the injection moulding process. The composite materials consisted of kenaf with the geometric core filler of the 20 mesh (992 µm), 40 mesh (460 µm) and bast filler (166.9 µm) were mixed with polypropylene based on the filler loadings of 10 up to 40 wt. %. The results showed that bast filled composites had the highest tensile strength of 19.52 MPa at 30 wt. %, compared to core filled composites. Instead, 20 mesh core filled composites were obtained had the highest flexural strength which values were 25 MPa and 29 MPa at 20 wt. % and 30 wt. %, respectively. While 40 mesh core filled composites had the highest values of 25.35 MPa at 40 wt. % of filler loading compared to bast filled composites. SEM micrograph images showed the good interfacial bonding of core filler which surrounded by PP leading to diffusion and permeation of bonding. In conclusion, the use of kenaf (core and bast) fillers as a reinforcement in composite materials is reasonable to maximise the use of fibre from natural sources.

Keywords: Injection moulding; kenaf filler; mechanical properties; polypropylene; SEM micrograph images

ABSTRAK

Serabut semula jadi menawarkan kekuatan penguat yang lebih baik bagi meningkatkan sifat mekanik dan fizikal komposit polimer. Walau bagaimanapun, bahan semula jadi ini masih belum diterokai sepenuhnya kerana sifat serabut itu sendiri yang mempunyai rintangan haba yang terhad dan sensitif terhadap lembapan. Keterbatasan ini akan melemahkan rekatan apabila digandingkan bersama matrik termoplastik semasa pemprosesan komposit. Maka kajian ini bertujuan untuk mengkaji kekuatan yang wujud antara pengisi (teras dan bast) kenaf sebagai penguat dalam komposit polipropilena dengan pelbagai geometri dan pembebanan melalui proses pengacuanan suntikan. Bahan komposit yang terdiri daripada kenaf dengan geometri pengisi teras 20 mesh (992 µm), teras 40 mesh (460 µm) dan pengisi bast (166.9 µm) yang dicampur dengan polipropilena berdasarkan pengisi sebanyak 10 hingga 40 % bt. Keputusan menunjukkan komposit berpengisi bast mempunyai nilai kekuatan tegangan yang tertinggi sebanyak 19.52 MPa pada 30 % bt., berbanding komposit berpengisi teras. Sebaliknya, komposit berpengisi teras 20 mesh pula didapati mempunyai kekuatan lenturan yang tertinggi sebanyak 25 MPa dan 29 MPa masing-masing pada 20 dan 30 % bt. Manakala komposit berpengisi 40 mesh mempunyai kekuatan lenturan bernilai 25.35 MPa pada beban 40 % bt., berbanding komposit berpengisi bast. Keputusan mikrograf SEM menunjukkan ikatan antara muka yang terbaik terbentuk oleh pengisi teras kenaf yang dikelilingi sepenuhnya dengan PP, dengan ikatan terbentuk melalui penyebaran dan penyerapan. Kesimpulannya, penggunaan pengisi (teras dan bast) kenaf sebagai bahan penguat dalam komposit adalah munasabah dalam usaha untuk memaksimumkan sepenuhnya penggunaan gentian daripada sumber semula jadi.

Kata kunci: Kekuatan mekanik; mikrografi SEM; pengacuanan suntikan; pengisi kenaf; polipropilena

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*Corresponding author; email: mkfadzly88@yahoo.com