Sains Malaysiana 40(4)(2011): 379–384 Effect of Aluminum Hydroxide Loading on the Compression Stress and Modulus, Thermal Conductivity and Acoustic Properties of Palm-Based Polyurethane Hybrid Composite (Kesan Penambahan Aluminium Hidroksida Terhadap Tegasan dan Modulus Mampatan, Kekonduksian Terma dan Sifat Akustik Komposit Hibrid Poliuretana Berasaskan Sawit) NOR RABBI’ATUL ‘ADAWIYAH NORZALI, KHAIRIAH HAJI BADRI* & MOHD ZAKI NUAWI ABSTRACT The effect of adding aluminum hydroxide (ATH) in the palm-based polyurethane hybrid composite was studied. The compression stress and modulus, thermal conductivity and acoustic property were determined. The hybrid composite was prepared by adding 10 wt% of oil palm empty fruit bunch fbre (EFB) followed by ATH at varying amount of 2, 4 and 6 wt% of the overall mass of the resin. The compression stress and modulus gave the highest values of 575 kPa and 2301 kPa, respectively at 2 wt% ATH. At 4 wt% ATH, the compression stress and modulus decreased to 431 kPa and 1659 kPa, respectively and further decreased at 6 wt% ATH to 339 kPa and 1468 kPa respectively. The k-value increased with the increment of the ATH loading exhibited a poor thermal conductivity. Sound absorption analysis indicated that the absorption coeffcient was higher at higher frequency (4000 Hz) for all samples with PU-EFB/ATH with 4% ATH showed the highest absorption coeffcient. Keywords: Acoustic property; aluminum hydroxide; palm-based polyurethane; thermal conductivity ABSTRAK Kesan penambahan aluminum hidroksida (ATH) ke dalam komposit hibrid poliuretana (PU) berasaskan sawit telah dikaji. Tegasan dan modulus mampatan, kekonduksian terma dan sifat akustiknya ditentukan. Komposit hibrid PU disediakan dengan menambahkan 10% bt serabut tandan kosong kelapa sawit (EFB) diikuti dengan penambahan ATH pada peratus penambahan divariasikan pada 2, 4 dan 6% bt mengikut berat keseluruhan resin. Tegasan dan modulus mampatan adalah pada nilai tertinggi pada penambahan 2% bt ATH iaitu masing-masing 338 kPa dan 2209 kPa. Pada 4% bt ATH, tegasan dan modulus mampatan menurun kepada masing-masing 431 kPa dan 1659 kPa dan semakin menurun dengan penambahan 6% bt ATH kepada masing-masing 379 kPa dan 1468 kPa. Nilai k meningkat dengan penambahan ATH dan mempamerkan sifat kekonduksian terma yang lemah. Analisis serapan bunyi menunjukkan koefsien serapan yang tinggi pada frekuensi tinggi (4000 Hz) untuk semua sampel dengan PU-EFB/ATH (4% ATH) menunjukkan pekali serapan tertinggi. Kata kunci: Aluminum hidroksida; kekonduksian terma; poliuretana berasaskan sawit; sifat akustik INTRODUCTION Polyurethane (PU) has been widely used in many felds such as aerospace, construction, sports and furniture. PU has many advantages for instance; high abrasion resistance, tear strength, excellent shock absorption and low density (Xu et al. 2008). PU foam has also been widely used as a thermal insulator. Addition of natural fbers as reinforcing fllers in polymeric materials has been widely used recently because of their properties which is environmental-friendly and cost effective. These lignocellulosic fbers offer low cost, low density, nonabrasive and enhanced energy recovery (Khairul Anuar Mat Amin & Khairiah Haji Badri 2007) as well as enhancing the mechanical strength of the bio-composites formed (Badri et al. 2004; Badri et al. 2005; Rozman et al. 2003). Bio-composite is an organic material that is easily caught fre. Even though the addition of EFB in the PU system enhanced its mechanical properties, it will also weaken the thermal properties. EFB can also decrease the fre-resistivity due to its property that is easily ignited. In order to increase not only the mechanical property but also the thermal property of palm-based PU, fre retardant namely, aluminum hydroxide is added besides EFB. Aluminum trihydroxide (ATH) which is also known as aluminum hydroxide has a molecular structure of Al(OH) 3 . Besides low cost, other benefts from ATH also include odorless, easy to handle, non-toxic, chemically inert and non-volatile (Bonsignore 1981; Wu et al. 2004). When composites flled with ATH is being heated and subsequently burned, the ATH can absorb the heat which is being applied to it. The absorbed heat is dispersed