Condition Monitoring of Wood Polymer Composite for Civil Engineering

Abstract

AbstractComposites such as Wood Polymer Composites (WPCs) comprised of polymer matrix and natural fiber is expected to increase in market growth due to its sustainable and environment-friendly nature. Polymers are widely utilized in the different types of fields and contributing the plastic waste in the atmosphere. The knowledge of this product regarding its long-term efficiency is still vague. Properties of recycled polymers, virgin polymers, and effects of weathering are aspects to be considered of WPCs in civil engineering study. Various weight percentage of fillers such as rice husk (RH) as well as recycled /waste polypropylene polymer (WPP) were incorporated together to influence its mechanical characteristics. The condition monitoring of the fabricated composites materials is treated through Ultra-Violet irradiation exposure to reveal its photodegradation. WPC specimens with several compositions of WPC pellets obtained from the industry were each mixed with 10%, 20% and 30% of homopolymer polypropylene (HPP) and later exposed to 1000, 2000, 3000, 4000, 5000 and 6000 h of UV irradiation under accelerated weathering. In this case of studies, WPP, RH and HPP are denoted by the letter A, B and C respectively. The specimens were then subjected tensile test, flexural test, FTIR analysis and morphological study of the fractured surface using Optical Microscope. The study revealed the WPC made from HPP recorded the highest tensile and flexural strength. On the other hand, the modulus of elasticity continued to increase alongside the decrease of HPP constituent. The Carbonyl Index (CI) value were calculated after FTIR to study the rate of photodegradation the specimens went through after UV irradiation exposure which give overall perspective for the civil engineering application. All the mechanical properties as well as decreased in values after they were being subjected to accelerate weathering which is important for building services interest. This is also in agreement with the CI value obtained after specimens were subjected to UV irradiation exposure. From the morphological study of fractured surface, it was observed that all WPC specimens experienced clean surface crack before UV irradiation. Formation of voids occurred after UV irradiation. Increased hours of UV irradiation and RH content caused larger voids formed which outcome in the reduce of mechanical characteristics of the specimens. However, for specimens made from WPC pellets, it was noticed that the tensile strength alongside the flexural strength fluctuates as the percentage of RH content raised. The total opposite however was observed for modulus of elasticity and flexural modulus. As RH content increased, these two properties also increased. The addition of HPP definitely helped to improves the mechanical properties and reduced the rate of photodegradation after the specimens were subjected to accelerated weathering. This is due to the RH fillers became less exposed to UV irradiation and humidity. Mixing HPP with WPP pellets helped in controlling the matrix pull outs. HPP also helped increase the interface bonding of RH and polymer matrix in the WPC pellet. In conclusion, adding optimum percentage of RH as fillers and HPP as additional reinforcements to WPP can improved the mechanical properties of WPC as well as reducing the rate of photodegradation when subjected to UV irradiation exposure.KeywordsWood polymer compositesWaste polypropyleneWeatheringUltra-violet irradiationPhotodegradation