Sains Malaysiana 40(7)(2011): 679–683

Effects of Liquid Natural Rubber (LNR) on the Mechanical Properties of LNR Toughened Epoxy Composite

(Kesan Getah Asli Cecair (LNR) Terhadap Sifat-Sifat Mekanik Komposit Epoksi Diperkuat LNR)

Lee Yip Seng*, Sahrim Hj. Ahmad, Rozaidi Rasid, Se Yong Eh Noum,

Yew Chin Hock & Mou’ad A. Tarawneh

School of Applied Physics, Faculty of Science & Technology

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E. Malaysia

Received: 23 October 2009 / Accepted: 5 August 2010

ABSTRACT

The effects of liquid natural rubber (LNR) on the morphology and mechanical properties of rubber modified epoxy were investigated. Epoxy composites were prepared in four different compositions of LNR (3, 5, 7 and 9phr) by using twin screw extruder. The samples for tensile, fracture toughness and impact tests were prepared according to ASTM D 638, D 5045 and D 256. The elastomeric nature of rubber can act as energy dissipating centre to cause the ductile fracture for the rubber modified epoxy. They was an obvious increment of fracture toughness where maximum value was observed with 3 phr LNR. A clear increment of impact strength at 3 phr LNR was observed, followed by a small increment at 5 phr and no further increment at 7 and 9 phr LNR. The tensile strength showed a similar trend with impact strength and Young’s modulus. SEM micrographs showed an increment of rubber particle size when the amount of LNR was increased and caused the mechanical properties to drop.

Keywords: Epoxy resin; liquid natural rubber; mechanical properties; toughness

ABSTRAK

Kesan getah asli cecair (LNR) terhadap morfologi dan sifat-sifat mekanik bagi komposit epoksi telah dikaji. Komposit epoksi disediakan di dalam empat komposisi LNR (3, 5, 7 & 9 phr) dengan menggunakan mesin penyemperitan skru-berkembar. Sampel bagi ujian tegangan, keliatan patahan dan hentaman disediakan mengikuti ASTM D 638, D 5045 and D 256. Elastomer getah dapat bertindak sebagai pusat penyesapan tenaga dan menyebabkan kepatahan mulur berlaku bagi epoksi termodifikasi getah. Peningkatan keliatan patahan yang jelas didapati dengan nilai maksimum adalah pada 3 phr LNR. Kenaikan yang jelas didapati bagi kekuatan hentaman pada 3 phr LNR dan diikuti dengan kenaikan kecil di 5 phr dan tiada kenaikan lebih lanjut pada 7 dan 9 phr LNR. Kekuatan tegangan telah menunjukkan satu kecenderungan yang sama dengan kekuatan hentaman dan modulus Young. Mikrograf SEM jelas menunjukkan kenaikan saiz partikel getah apabila jumlah LNR meningkat dan menyebabkan penurunan sifat-sifat mekanik.

Kata kunci: Keliatan; getah asli cecair; resin epoksi; sifat mekanik

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*Corresponding author; email: jansennlee@hotmail.com