Materials and Design 30 (2009) 557–562
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Thermal degradation of banana pseudo-stem filled unplasticized polyvinyl chloride (UPVC) composites E.S. Zainudin a,*, S.M. Sapuan a, K. Abdan a, M.T.M. Mohamad b a b
Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
a r t i c l e
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Article history: Received 25 February 2008 Accepted 23 May 2008 Available online 9 July 2008 Keywords: A. Natural materials A. Composites:. . ..polymer matrix C. Moulding
a b s t r a c t The thermal behaviour of banana pseudo-stem (BPS) filled unplastisized polyvinyl chloride (UPVC) composites was studied by means of thermogravimetric analysis. The effects of fiber loading and resin modification on the thermal stability of the composites were evaluated. Resin modifications were carried out by acrylic to improve the fiber–matrix adhesion. From the study, the thermal stability of the composites was found to be higher than that of BPS fiber and the UPVC matrix. It is shown that the incorporation of BPS filler decreases the thermal stability of BPS/UPVC composites for the case of non acrylic. The thermal stability of BPS/UPVC composite with acrylic is found to be higher compared to BPS/UPVC composite without acrylic. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction The increase concern of environments resulted from the use of synthetic fiber reinforced polymer composite has triggered research effort to develop new forms of composites such as natural fiber composites. Besides possessing good specific physical properties, natural fiber composite is also cost-effective and environmentally friendly. The use of natural fibers such as banana pseudo-stem, oil palm empty fruit bunch and rayon fiber in some polymers has demonstrated promising results in the past especially in the presence of the interfacial bonding agents [1–3]. According to Pothan and Thomas [1], the storage modulus value was found to be higher for the silane treated banana fiber/polyester composites as compared to pure PE resin. In the case of oil palm empty fruit bunch fiber, Rozman et al. [2] found that the composites with coupling agent showed higher flexural and impact strength than those with untreated fiber. Another finding by Escamilla et al. [3] that grafted rayon had better thermal properties than ungrafted rayon due to good compatibility and homogeneous. These composites not only have good mechanical and thermal characteristics but they also do not pose health hazard and their uses are cost-effective [4–7]. Polyvinyl chloride (PVC) is a thermally unstable material, especially at high temperature in the presence of oxygen and humidity. The inclusion of natural filler in polymer that affects the thermal performance of composites has been studied in the past [3,5–9]. Since most polymers are processed at high temperature, thermal * Corresponding author. Tel.: +60 3 89466317; fax: +60 3 86567122. E-mail address:
[email protected] (E.S. Zainudin). 0261-3069/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.matdes.2008.05.060
stability of natural fibers or fillers is one of the factors to be considered in developing natural fiber composites [9,10]. In this paper, thermal decomposition behaviour of BPS/UPVC composites is presented based on thermogravimetric and derivative thermogravimetric analyses. This study aimed at observing the variation in thermal degradation by reinforcing the UPVC with BPS filler at different mass fractions. 2. Experimental 2.1. Materials The matrix used in this study was UPVC (IR064) supplied by Polymer Resources Sdn. Bhd., Kelang, Selangor, Malaysia. This UPVC was a medium molecular weight resin designed for general purpose application. It was a rigid polymer with amorphous structure. Some additives were inserted together into the pure PVC to make it unplastisized, which were in the powder form. The BPS filler used in this study was taken from banana tree trunk, which is known as a ‘pseudo-stem’. Detail properties and the type of banana used cannot be revealed by the supplier (Baala Bharat Agri Industries, Andhra Pradesh, India) due to the confidential nature of the information and data. Tables 1, 2a and b show the important properties of BPS filler and UPVC respectively. 2.2. Incorporation of BPS filler Melt blending was carried out at 150 °C and 50 rpm rotor speed in a HAAKE Rheomixer having a mixing chamber attachment. The
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E.S. Zainudin et al. / Materials and Design 30 (2009) 557–562
Table 1 Properties of BPS filler [4]
Table 4 Blend of formulation of BPS/UPVC composite
Property
Value 3
Density (g/cm ) Elongation at break (%) Cellulose content (%) Lignin content (%) Tensile strength (MPa) Young’s modulus (GPa) Diameter (lm) Microfibrillar angle (°) Lumen size (lm)
Constituent
1.35 5–6 63–64 5 550 ± 6.7 20 120 ± 5.8 11 5
Table 2a Properties of UPVC [1] Specification
Value
Units
Specific gravity Specific heat Thermal conductivity Coefficient of linear expansion Tensile strength @20 °C Elongation (Min) Modulus of elasticity Water absorption
1.4–1.43 0.25 0.13 5.0 10 5 500 80 1200-1500
