Sains Malaysiana 50(8)(2021): 2407-2417

http://doi.org/10.17576/jsm-2021-5008-22

Non-Isocyanate Polyurethane (NIPU) Based on Rubber Seed Oil Synthesized via Low-Pressured Carbonization Reaction

 (Poliuretana Bukan Isosianat (NIPU) Berasaskan Minyak Biji Getah yang Disintesis secara Tindak Balas Karboksinasi Bertekanan-Rendah)

R.A. RADEN SITI AMIRAH¹, M.A. FAIZA¹* & A. ZULIAHANI²

¹School of Industrial Technology, Universiti Teknologi MARA, 40450 Shah Alam, Selangor Darul Ehsan, Malaysia

²Faculty of Applied Sciences, Universiti Teknologi MARA, Perlis Branch, 02600 Arau, Perlis Indera Kayangan, Malaysia

Diserahkan: 27 April 2020/Diterima: 18 Disember 2020

abstract

Epoxidised rubber seed oil (ERSO) was successfully synthesized into non-isocyanate polyurethane via carboxylation method whereas peroxoformic acid was formed by in-situ reaction for epoxidation. The effects of temperature and ratio of hydrogen peroxide and formic acid to rubber seed oil carboxylation were studied. The optimum temperature for the epoxidation reaction was found at 50 °C to avoid ring opening reaction of epoxy whilst the optimum ratio of hydrogen peroxide and formic acid is equal molar of double bond: formic acid at 1:2 and 1:1, respectively. At a lower concentration of hydrogen peroxide and formic acid, the oxirane ring was stable due to the lower hydrolysis (oxirane cleavage) of an epoxide. The effect of using low content of formic acid tends to minimize unwanted epoxide ring opening to occur and make the epoxidation rate increased with increasing of oxirane number. Fourier transform infrared (FTIR) spectral displayed the presence of an epoxy functional group at 822 cm^-1 and the disappearance of double bond peak at 3011 cm^-1 corresponding to epoxidised oil and carbonyl group confirmed the epoxidation reaction had taken place. ¹H-NMR was used to confirm the formation of carboxylate functionality after the reaction of epoxy at δ 4.83 and 4.61 ppm. In conclusion, ERSO has great potential to be used as a precursor in producing environmentally friendly non-isocyanate polyurethane.

Keywords: Carboxylated oil; epoxidised oil; non-isocyanate; polyurethane; rubberseed oil

ABSTRAK

Minyak biji getah terepoksi (ERSO) berjaya disintesis menjadi poliuretana bukan isosianat melalui kaedah karboksilasi sedangkan asid peroksoformik dibentuk oleh reaksi in-situ untuk epoksidasi. Kesan suhu dan nisbah hidrogen peroksida dan asid formik kepada karboksilasi minyak biji getah dikaji. Suhu optimum untuk tindak balas epoksidasi didapati pada suhu 50 °C untuk mengelakkan tindak balas pembukaan cincin epoksi sementara nisbah optimum hidrogen peroksida dan asid formik adalah molar ikatan berganda yang sama: asid formik masing-masing pada kadar 1: 2 dan 1: 1. Pada kepekatan hidrogen peroksida dan asid formik yang lebih rendah, cincin oksirana stabil kerana hidrolisis yang rendah (pembelahan oksirana) epoksida. Kesan penggunaan kandungan asid formik yang rendah cenderung untuk mengurangkan pembukaan cincin epoksida yang tidak diingini berlaku dan menjadikan kadar epoksidasi meningkat dengan bertambahnya bilangan oksirana. Spektrum inframerah transformasi Fourier (FTIR) memperlihatkan kehadiran kumpulan berfungsi epoksi pada jarak 822 cm^-1dan hilangnya puncak ikatan berganda pada 3011 cm^-1 yang sepadan dengan minyak terepoksi dan kumpulan karbonil mengesahkan reaksi epoksidasi telah berlaku. ¹H-NMR digunakan untuk mengesahkan pembentukan fungsi karboksilat setelah tindak balas epoksi pada δ 4.83 dan 4.61 ppm. Kesimpulannya, ERSO berpotensi besar untuk digunakan sebagai pendahulu dalam menghasilkan poliuretana bukan isosianat yang mesra alam.

Kata kunci: Bukan isosianat; minyak getah; minyak karboksilasi; minyak terepoksi; poliuretana

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*Pengarang untuk surat-menyurat; email: ahmadfaiza@uitm.edu.my