Showing papers by "Azman Hassan published in 2003"

Leakage current and surface discharge phenomena: effect on tracking and morphological properties of LLDPE-natural rubber compounds

Abstract: Polymeric insulators are widely used for high voltage outdoor insulating application due to their substantial advantages compared to the porcelain and glass insulators. Although polymer materials have been proven good, research on development of new polymer-based materials is still on going since the benefits of using polymeric materials are not yet utilised to their full potential. In this work, a new formulated thermoplastic elastomer materials that are composed of linear low-density polyethylene (LLDPE) and natural rubber (NR) filled with different loadings of alumina trihydrate (ATH) fillers is presented. A surface tracking and erosion test is conducted to investigate the characteristics of leakage current on the material surface under the influence of wet contaminated conditions. A computer-based leakage current monitoring system is developed to monitor the leakage current waveform pattern as well as its frequency spectrum. The scanning electron microscope is used to investigate the morphological properties of the materials before and after the tracking test.

Impact Properties of Oil Palm Empty Fruit Bunch Filled Impact Modified Unplasticised Poly (vinyl Chloride) Composites

Abstract: Komposit bertetulang tandan kosong buah sawit (EFB) merupakan bidang yang terkini muncul dalam teknologi polimer. EFB ialah pengisi berkos rendah serta ketumpatan rendah, bersifat tentu yang tinggi dan tidak bersifat menghakis. Oleh itu komposit jenis ini mempunyai pelbagai kebaikan berbanding dengan komposit bergentian. Objektif utama kajian dalam kertas kerja ini adalah untuk mengetahui kesan penambahan pengisi EFB dan pengubahsuai impak, iaitu polietilena berklorin (CPE) dan akrilik terhadap sifat mekanikal komposit PVC–U berpengisi EFB. Semasa penyediaan sampel, PVC–U dan additif pada mulanya telah diadun kering dengan menggunakan pengadun sebelum disebatikan menjadi kepingan dengan menggunakan penyebati dua–pengguling. Alat penekan panas telah digunakan untuk menghasil spesimen untuk ujian impak dengan menggunakan alat jenis pendulum dalam mod Izod. Keputusan daripada ujian impak sampel PVC–U tanpa pengisi untuk kedua–dua pengubahsuai impak telah menunjukkan perubahan dari mod rapuh kepada mod mulur dengan bertambahnya kepekatan pengubahsuai impak. Penambahan pengisi EFB ke dalam PVC–U tanpa terubahsuai dan PVC–U terubah suai telah mengakibatkan pengurangan kepada kekuatan impak. Apabila EFB bertambah daripada 10 sehingga 40 phr, pengurangan kekuatan impak adalah 40% untuk PVC–U berpengubahsuai impak akrilik dan 30% untuk PVC–U berpengubahsuai CPE. Hanya sedikit pengurangan kekuatan impak untuk komposit PVC–U tanpa terubah suai. Kesan kekurangan dari pengisi terhadap prestasi impak adalah disebabkan ketidakmampuan pengisi untuk melepaskan tegasan melalui mekanisme yang dikenali sebagai alahan ricihan sebelum patah. Pengubahsuai impak telah didapati berkesan untuk meningkatkan kekuatan impak komposit PVC–U berpengisi EFB. Bagaimanapun, keberkesanannya berkurangan dengan pertambahan pengisi. Kekuatan impak PVC–U berpengubahsuai CPE adalah lebih tinggi daripada PVC–U berpengubahsuai akrilik pada pengisi muatan 20 phr dan lebih. Kata kunci: Tandan buah kelapa sawit; poli (vinil klorida); pengubahsuaian impak; kekuatan impak; komposit Oil palm empty fruit bunch (EFB) reinforced composite is an emerging area in polymer technology. EFB is a low cost filler with low density, high specific properties as well as being non-abrasive. This type of composites offers several advantages comparable to those of conventional fiber composites. The main objective of the investigation reported in this paper is to study the effect of EFB filler loading and impact modifiers, namely chlorinated polyethylene (CPE) and acrylic on the mechanical properties of EFB filled–PVC–U composites. In preparing the samples, the PVC-U resins and the additives were initially dry blended using a laboratory blender before being milled into sheets using a two–roll mill. Test specimens were prepared using a hot press and impact tested using a pendulum type machine according to Izod mode. The results from the impact test showed that the unfilled PVC–U samples of both impact modifiers changes from brittle to ductile mode with increasing impact modifier concentration. The incorporation of EFB into unmodified PVC–U and modified PVC–U has resulted in the reduction of impact strength. As the EFB filler content increases from to 10 to 40 phr, impact strength reduction of about 40% and 30% was observed for acrylic–modified PVC–U and CPE–modified PVC–U, respectively. The impact strength reduction was only marginal for unmodified PVC–U composites. The detrimental effect of fillers on the impact performance was due to the volume taken up. Fillers unlike the matrix are incapable of dissipating stress through the mechanisms known as shear yielding prior to fracture. The impact modifier was found to be effective in enhancing the impact strength of EFB–filled PVC–U composites. However, the effectiveness decreases with increasing filler loadings. The impact strength of CPE–modified PVC–U was higher than acrylic–modified PVC–U at filler loading at 20 phr and higher. Key words: oil palm empty fruit bunch; poly (vinyl chloride); impact modifier; impact strength; composites

Material Properties Mechanical and morphological properties of PP/NR/LLDPE ternary blend—effect of HVA-2

Abstract: Improvements in impact strength of polypropylene can be sought by melt blending with rubbers. In this study, blends of PP, natural rubber and linear low density polyethylene (PP/NR/LLDPE) were prepared in a laboratory scale extruder. The rubber content in the ternary blend was at 10 and 20% with LLDPE content fixed at 25% of the overall plastics content. After mixing and pelletising, the samples were injection moulded and tested for mechanical properties. The study showed that the mechanical properties were modified significantly with the addition of HVA-2. The incorporation of HVA-2 into the ternary blend improved the elongation at break, but no significant change was observed in the yield strength values. At both testing temperatures of 0 and 27 °C, the impact properties of 64/20/16 PP/NR/LLDPE ternary blends improve significantly as HVA-2 increases from 0 to 7.5%. However, the 72/10/18 PP/NR/LLDPE shows an optimum value at 0.5% HVA-2 concentration. SEM study shows that the number of holes due to the extraction of NR particles reduced significantly upon the addition of HVA-2. This observation indicates that the HVA-2 has crosslinked the rubber phases. The crosslinking of the rubber particles will increase the cohesive strength of natural rubber allowing it to undergo greater deformation before cohesive failure. It is also notable that the crosslinking can prevent the elastomer domain from re-aggregation and breakdown at shear stresses prevailing during the molding process and maintains mechanical properties effectively. In this study, the HVA-2 was also shown to be an effective compatibilizer by reducing the interfacial tension and improving adhesion between immiscible polymers, thus increasing the compatibility of the blend.  2002 Elsevier Science Ltd. All rights reserved.

The Effect of Blending Acrylic Grafted PVC and PVC K–66 with ABS on Impact and Flexural Properties

Abstract: Adunan antara ABS dan PVC telah dikaji. Adunan yang mempunyai pelbagai nisbah ini disediakan dengan teknik pengadunan leburan. ABS yang mempunyai ketegaran tinggi, hentaman yang sederhana dan hentaman paling tinggi digunakan sebagai polimer dasar. Manakala, PVC bercangkuk akrilik dan PVC K–66 ditambah ke dalam ABS. Ujian hentaman Izod dititik–beratkan. Kekuatan hentaman adunan meningkat berikutan dengan peningkatan berat molekul PVC. Yang menariknya, kekuatan hentaman yang paling tinggi wujud apabila PVC bercangkuk akrilik diadunkan bersama ABS berhentaman paling tinggi. Walau bagaimanapun, penurunan modulus lenturan berlaku apabila PVC ditambah ke dalam ABS. Penurunan modulus lenturan yang paling minimum ialah adunan antara PVC K–66 dan ABS bertegaran tinggi. Keputusan yang diperolehi adalah serasi dengan pemeriksaan morfologi. Mikroskopi imbasan elektron (SEM) menunjukkan semakin tinggi kandungan PVC, semakin tinggi kekuatan hentaman. Kata kunci: ABS; PVC; kekuatan hentaman; modulus lenturan; SEM Blends of acrylonitrile butadiene styrene (ABS) and poly(vinyl chloride) (PVC) were studied. The blends were prepared in different ratios by melt blending technique. High rigidity; medium impact and super high impact ABS were used as the base polymer. Acrylic grafted PVC and PVC K–66 were incorporated into the blends. Particular emphasis was on Izod impact test. The impact strength of the blends increased with increasing content of PVC. Interestingly, the result shows that the highest impact strength occurs when acrylic grafted PVC was added into super high impact ABS. However, it was observed that when PVC is incorporated in ABS, there is a decrease in the flexural modulus. The least decrease occurred when PVC K–66 was added into high rigidity ABS. These observations are consistent with the morphological studies. Scanning electron microscopy (SEM) revealed that an increase in PVC content results in greater ductility. Key words: ABS; PVC; impact strength; flexural modulus; SEM

Effect of SEBS on Impact Strength and Flexural Modulus of Polystyrene/Polypropylene Blends

Abstract: Pengadunan polistirena (PS) dengan polipropilena (PP) dibangunkan dengan objektif untuk mengatasi masalah kerapuhan PS dan meningkatkan kekuatan hentaman pada suhu bilik. Walau bagaimanapun, pengadunan PS dan PP adalah tidak serasi. Kajian terdahulu menunjukkan bahawa ko–polimer blok seperti stirena–b –(etilena–co– butilena)–b–stirena (SEBS) adalah agen penyerasi yang baik bagi adunan PS/PP ini. Kajian ini juga menyelidiki kegunaan SEBS dalam meningkatkan keserasian adunan PS/PP. Mesin penyemperit skru berkembar Brabender PL2000, digunakan untuk melakukan adunan PS/PP pelbagai komposisi dalam julat 90–60% PS yang mengandungi kandungan SEBS yang berbeza dalam julat 5–25 phr, dan diacu–suntikan bagi menentukan sifat mekanikal. Keputusan yang didapati daripada sifat mekanikal menunjukkan peningkatan sifat adunan yang menunjukkan kesan penyerasian dalam sistem adunan. Penambahan SEBS telah meningkatkan kekuatan hentaman adunan tetapi mengurangkan kekuatan dan modulus lenturan. Adunan 90/10 PS/PP dengan 25 phr SEBS menunjukkan kekuatan hentaman yang unggul. Yang menarik, keputusan menunjukkan bahawa SEBS lebih berkesan pada kandungan PP yang rendah. Kata kunci: PS; PP. SEBS; sifat mekanikal; adunan polimer Blends of Polystyrene (PS) with Polypropylene (PP) were developed with the objective to overcome the inherent brittleness of PS and enhance the impact strength at room temperature. However, the blends of PS and PP were known to be immiscible. Previous studies have concluded that the block copolymer such as styrene–b– (ethylene–co–butylenes)–b–styrene (SEBS) is good compatibiliser for this PS/PP blends. The present study investigates the use of SEBS as a compatibiliser in this immiscible blend system. Using a Brabender PL2000 twin–screw extruder, blends of PS/PP in various composition range of 90–60 wt% PS containing different amount of SEBS in the composition range of 5–25 phr were prepared and injection molded to evaluate for mechanical properties. The results obtained from mechanical properties show some improvement in the properties of the blends indicating some compatibilisation effect in the blend system. The addition of SEBS enhanced the impact properties of the blends but reduced the flexural strength and flexural modulus. The blends of 90/10 PS/PP with 25 phr SEBS gave superior impact properties. Interestingly, the results show that SEBS is more effective at lower PP content. Key words: PS; PP; SEBS; mechanical properties; polymer blends

Mechanical, chemical & flammability properties of ABS/PVC blends

Abstract: The first completely synthetic plastic, phenol-formaldehyde, was introduced by Baekeland in 1909, nearly four decades after Hyatt had developed a semisynthetic plastic-cellulose nitrate (Chanda and Roy, 1993). In 1927 poly(vinyl chloride) (PVC) and cellulose acetate were developed, and 1929 saw the introduction of urea- formaldehyde (UF) resins (Chanda and Roy, 1993). The development of new polymeric materials proceeded at an even faster pace after the war. Epoxies were developed in 1947, and acrylonitrile-butad iene-styrene (ABS) terpolymer in 1948 (Chanda and Roy, 1993). The next two decades saw the commercial development of a number of highly temperature-resistance materials. More recently, other new polymer materials were introduced, including several exotic materials which are mostly very expensive.