Fabrication and characterization of gum Arabic bonded Rhizophora spp. particleboards Ali Abuarra a , Rokiah Hashim b,⇑ , Sabar Bauk c , Sivamany Kandaiya a , Ehsan Taghizadeh Tousi a a Medical Physics, School of Physics, Universiti Sains Malaysia, 11800 Penang, Malaysia b Division of Bioresource, Paper and Coatings Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia c Physics Section, School of Distance Education, Universiti Sains Malaysia, 11800 Penang, Malaysia article info Article history: Received 3 January 2014 Accepted 14 March 2014 Available online 28 March 2014 Keywords: Gum Arabic Rhizophora spp. particleboards Physical Mechanical Scanning electron microscopy abstract Gum Arabic (GA) was used as a binder for the fabrication of Rhizophora spp. particleboards. The physical and mechanical properties of the bioadhesive bonded particleboards, including moisture content, inter- nal bond (IB) strength, thickness swelling (TS), water absorption (WA) and field-emission scanning elec- tron microscopy (FESEM) were used to characterize the manufactured particleboards. Three different particle sizes of the Rhizophora spp. with four adhesive levels were utilized. Results revealed that the addition of GA into the particleboards noticeably improved panel overall properties. The GA bonded par- ticleboards resulted in smoother surfaces, more rigid texture and better internal bonding strength com- pared to binderless particleboards made without using any adhesive. All specimens had internal bond strength of more than the minimum requirement of the Japanese Industrial Standard JIS A-5908 Type- 8 of 0.15 N/mm 2 and were noticed to increase by increasing the adhesive level. However the GA bonded particleboards had higher percentage of WA and the TS compared with the binderless boards. Micro- scopic study also revealed that particleboards bonded with the gum had better contact compared to the binderless boards. Based on these results, it could be concluded that gum Arabic is an effective natural substance that could be added to manufacture particleboards to improve some of panels’ physical and mechanical properties. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Rhizophora spp. is a mangrove tree which can be found growing profusely in the tropical and subtropical coastal regions. All Rhizo- phora species are closely similar in tree form. Currently, they are mainly used as firewood, timber, charcoal, construction material and dyes due to the high tannin content of the bark of most Rhizo- phora spp. The trees are also used for their lignocellulose for chip- board, pulpwood, newspaper and cardboard manufacture [1]. In traditional medicine, they are used to treat angina, boils, leprosy, fever, malaria, diahrrea, dysentery, and fungal infections [2]. Gum Arabic is the dried gummy exudates produced from the stems and branches of Acacia tree. There are more than 1000 spe- cies of Acacia, but only two of the Acacia species are significant for commercial purposes: Acacia senegal (L). Willd which produces the best type of gum and provides the bulk for world trade and Acacia seyal (Del.) which produces a lower grade of gum [3]. Gum from A. senegal is considered as the best quality and widely used species of natural plant gums because it contains low quantities of tannins [4]. Gum Arabic is commercially available in different shapes as white to orange-brown solid spheroidal tears of varying sizes with a matt surface texture, white to yellowish-white flakes, granules, powder, roller dried, or spray-dried material [5]. Acacia trees are abundant in central Sudan, central and West Africa, tropical and semitropical areas of the world [6,7]. However, Sudan is considered as the world’s largest producer followed by Nigeria, Chad, Mali and Senegal [8]. Gum Arabic has wide domestic applications such as in foodstuff, dairy products, beverages, confectionary and gummy candies textile, paints, ink, liquid adhesives, pharmaceutical and cosmetic products [9]. Gum Arabic tears and powder are shown in Fig. 1. Recently, considerable research is being focused on the suitabil- ity of the mangrove hardwood Rhizophora spp. as tissue equivalent phantom material [10–21]. It was found that Rhizophora spp. has the potential to be used as tissue equivalent material. However, Rhizophora spp. wood is preferred to be used as fabricated particle- boards, because using the raw material of Rhizophora spp. is not easy due to many reasons like the limited trunk diameter of the majority of trees, where the maximum diameter which is available http://dx.doi.org/10.1016/j.matdes.2014.03.032 0261-3069/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +60 4 6535217; fax: +60 4 6573678. E-mail address: hrokiah@usm.my (R. Hashim). Materials and Design 60 (2014) 108–115 Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes