Sains Malaysiana 49(9)(2020): 2073-2081

http://dx.doi.org/10.17576/jsm-2020-4909-05

Effects of Sulphuric Acid Concentrations during Solvolysis Process of Carbon Fiber Reinforced Epoxy Composite

(Kesan Kepekatan Asid Sulfurik semasa Proses Solvolisis Komposit Epoksi yang Diperkuat oleh Gentian Karbon)

MUHAMMAD FALAQ MUHAMMAD FAISAL¹, AZMAN HASSAN¹*, KHONG WUI GAN², MOHD NAZRUL ROSLAN³ & AZRIN HANI ABDUL RASHID³

¹School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Darul Takzim, Malaysia

²University of Southampton Malaysia, 79200 Iskandar Puteri, Johor Darul Takzim, Malaysia

³Department of Mechanical Engineering Technology, Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, 84600 Pagoh, Johor Darul Takzim, Malaysia

Received: 15 January 2020/Accepted: 10 May 2020

ABSTRACT

Developing a cost-effective technique of reclaiming carbon fibers without significantly deteriorating their quality has gained much importance. This paper reports on reclaiming carbon fibers from the carbon fiber reinforced polymer (CFRP) by solvolysis technique using sulphuric acid. The main objective of this work was to determine the lowest sulphuric acid concentration which can remove the epoxy resin from the composites, at room temperature and atmospheric pressure. The sulphuric acid concentrations used ranged from 11 to 18 mol L^-1 with 30 min reaction time and 50 mL volume. Thermogravimetric analysis (TGA) showed that the fiber content of the composites is 68% by weight.  From the solvolysis process, mass of decomposed epoxy resin decreased with decreasing acid concentrations. SEM images show that the residual epoxy adhering to the fibers after solvolysis increased with decreasing molarity. Acid concentrations lower than 15 M were found to be not effective in removing the epoxy resin from the carbon fibers. The tensile strength and Young’s modulus of all the reclaimed fibers is marginally lower than the untreated carbon fibers. The tensile strength was found to increase as the acid concentration decreases with fibers in 15 M acid showed the highest tensile strength of 3.43 GPa (99.1% strength retention). Similar trend was also observed for Young’s modulus. The study shows the potential of sulphuric acid to reclaim carbon fiber from the CFRP with 15 M giving the optimum properties in terms of tensile properties retention and epoxy resin decomposition.

Keywords: Carbon fiber reinforced polymer; epoxy resin; solvolysis; sulphuric acid; tensile properties

ABSTRAK

Penghasilan teknik yang kos efektif untuk memperoleh gentian karbon tanpa mengurangkan kualiti secara ketara telah menjadi semakin penting. Kertas ini melaporkan tentang perolehan gentian karbon daripada gentian karbon diperkuatkan dengan polimer (CFRP) melalui teknik solvolisis menggunakan asid sulfurik. Objektif utama kerja ini adalah untuk menentukan kepekatan asid sulfurik terendah yang boleh menguraikan resin epoksi daripada komposit pada suhu bilik dan tekanan atmosfera. Kepekatan asid sulfurik yang digunakan dalam julat antara 11 dan 18 mol L^-1dengan masa tindak balas 30 min dan isi padu 50 mL. Analisis Termogravimetrik (TGA) menunjukkan bahawa kandungan gentian adalah 68% daripada berat komposit. Daripada proses solvolisis, jisim resin epoksi yang terurai berkurangan dengan berkurangnya kepekatan asid. Imej SEM menunjukkan baki epoksi yang melekat pada gentian selepas solvolis bertambah dengan berkurangnya molariti. Pada kepekatan asid kurang daripada 15 M, didapati tidak berkesan dalam menguraikan resin epoksi daripada gentian karbon. Kekuatan tegangan dan modulus Young untuk semua gentian yang diperoleh adalah sedikit rendah daripada gentian karbon yang tidak dirawat.  Kekuatan tegangan menunjukkan peningkatan apabila kepekatan asid berkurang dengan gentian dalam asid 15 M menunjukkan kekuatan tegangan tertinggi iaitu 3.43 GPa (99.1% pengekalan kekuatan). Aliran sama ditunjukkan untuk modulus Young. Kajian ini menunjukkan asid sulfurik berpotensi untuk memperoleh gentian karbon daripada CFRP dengan 15 M memberikan keadaan paling optimum daripada segi pengekalan kekuatan tegangan dan pemisahan resin epoksi.

Kata kunci: Asid sulfurik; polimer diperkuat gentian karbon dikitar semula; resin epoksi; sifat mekanikal; solvolis

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*Corresponding author; email: azmanh@cheme.utm.my