Wood Polymer Composites

In the recent year, the needs for environmentally-friendly, low-price, and recyclable with higher strength laminates have been improved significantly. In this regard, the wood fillers based polymer laminates have fascinated the investigators owed to their lower price and eco-friendliness as they are formulated from waste wood fillers and better physical and mechanical characteristics. These laminates were fabricated by reinforcing the waste wood fillers in the polymeric resin using different manufacturing techniques like compression molding, hand layup, injection molding, three-dimensional printing, and extrusion. A considerable quantity of research investigation has been examined on the characterization and testing of wood-based polymer composites for different applications. This chapter presents the thermal, water absorption, and mechanical characteristics of thermoplastics, biopolymers, and thermosets have been discussed. The present chapter’s conclusion offers a better understanding of the wood laminates, which will inspire the investigators for further research investigations and advancements of new wood laminates for the developed applications.

Wood polymer composites (WPCs) is a category of natural fiber composites (NFCs) in which comparatively short fibers such as saw dust and wood flour are used to reinforce the plastics. Besides all the advantages of NFCs which are concern to sustainable material and environment, WPCs are easier to manufacture and economic. These qualities of WPCs have made it strong alternative for many conventional materials. This chapter presents an overview of manufacturing processes involved in the production of WPCs with their advantages and disadvantages. It also discusses over the preparation of wood fibers and suitability of manufacturing techniques for different kinds of fibers and plastics. WPC’s properties such as strength, durability and external finishing highly depend upon their development process. A comparative discussion over properties of finished WPC products is included in the present chapter. It also enlighten the key factors involved in manufacturing process of WPCs such as process temperature, moisture content, heat evolved etc.

This chapter presents an overview of different physical, chemical and biological methods used to improve the mechanical and thermal properties of wood and wood plastic composites. The physical methods addressed contemplate plasma, corona, ultraviolet (UV) radiation, ultrasound, heat treatments, fibre beating and electron radiation. The chemical methods discussed in this work were alkali, benzyl, acetyl, acryl, silane, permanganate, among others. Biological treatments, such as enzyme and fungal treatment were also reviewed. Methods used to impregnation and chemical modification of wood using sustainable reagents were also presented. The furfurylation of wood, the impregnation and polymerization of lactic acid directly in wood structure and the usage of citric acid are also discussed as natural compounds that can be used to promote wood chemical modification. The usage of coupling agents or compatibilizers from renewable and non-renewable sources and their impact on the thermo-mechanical properties of the wood-plastic composites will be discussed. Moreover, the chemistry and the mechanism of compatibility between the wood and polymer matrix will be properly evaluated.

Several factors such as type of wood species e.g. soft wood, hard wood, wood flour (WF) particle size, particle shape, particle aspect ratio, type of polymer matrices, dispersion of wood flour in polymer matrix as well as interfacial interaction i.e. interfacial adhesion between wood flour particle and polymer matrix affect the properties of Wood plastic-composite (WPC). Among the above factors, the most significant and important factor is the interfacial adhesion between WF and polymer matrix that affects the properties of WPC materials largely. WPC material obtained by normal blending of wood flour and polymer matrix, due to their incompatibility, does not exhibit improved properties. The poor adhesion or incompatibilization at the interface between WF and polymer matrix decreases the mechanical properties of WPC materials that limits the use of WF as filler in polymer matrices. Hence, compatibilization between wood flour and polymer matrices is the main focus of this chapter. By reading this chapter reader will learn the chemistry and mechanism of compatibility of different compatibilizing systems (such as coupling agents as well as silane treatments, acetylation and benzylation of wood flour, etc.) and their effect on the properties of WPC materials. After reading this chapter reader will also know the effect of thermal treatment of wood flour, effect of nanofillers addition as well as wet pulverization of WF on the properties of WPC materials.

This work addresses the role of various imaging techniques in investigating the morphology of the wood and wood polymer composites (WPC). Micrographs from the scanning electron microscope (SEM) and field emission scanning electron microscope (FESEM) were helpful in assessing the surface changes in the fibre and matrix due to the fibre treatment and coupling agent, interfacial adhesion between the fibre-matrix, failure behavior under various loads and degradation effects due to the aging. Images from the transmission electron microscope (TEM) were effective in determining the dispersion characteristics of additives in the polymer matrix. In addition to the microstructural images, quantitative assessment of the surface changes in the fibre and matrix can be obtained from the laser scanning microscope (LSM) and atomic force microscope (AFM) images.

The world has been facing a huge environmental impact due to global warming, which sometimes lead to unprecedented natural disasters creating a crisis for the present and future generations to come. Sustainable development, which was a far cry in the past, has now been a burning topic and desire in all aspects of human endeavour towards development. In polymer composites, reinforcing materials from natural resources such as wood have been attracting a lot of interest from researchers worldwide due to their low cost, and abundance in making an environment-friendly polymer composite. Waste or by-products from wood milling industries in the form of fibre, sawdust or wood flour (WF) have been potentially used as a filler material in various wood polymer composites (WPCs). Although lower-cost attracts their use as a reinforcer and/or filler, WPCs do have serious issues in low-performance aspect and higher moisture absorption. These disadvantages are scopes for researchers and organisation to address. Nonetheless, various WPCs as commercial products are available in the market and are being successfully used. To leverage the benefits of WPCs, a critical criterion for consideration is their mechanical performance. Bulk mechanical properties such as tensile, flexural, impact etc., are crucial to find the limitations and also to evaluate their load carrying capacity which can potentially define their area of application. In the present study, an in-depth analysis of different mechanical properties reported for various WPCs along with different theoretical modeling techniques, used previously have been summarized.

Wood polymer composites (WPCs) are continuously extending the field of applications of composites and already they have replaced several conventional materials from exterior and interior building components. The suitability of WPC for an application primarily depends upon their mechanical properties such as strength, stiffness and toughness. These properties of WPC depend upon the constituent materials, such as fiber & matrix, and bonding between them. However, some other parameters such as moisture content and manufacturing techniques also play an important role. Although, there are several methods successfully established to improve the strength and performance of WPCs. This chapter discusses about, various parameters on which mechanical properties of cellulosic fibers and polymeric matrix material depends. It also includes study of mechanical properties of natural fiber composites (NFCs) and WPCs. The experimental and theoretical method for evaluating mechanical properties of WPCs have also been presented. It also discusses various techniques for improving the mechanical properties of WPCs.

As the boundaries of engineering materials are pushed there is a wide increase in the demand for composite materials. In the past decade composite materials have been at the forefront of many engineering advancements. One of the category of composites which is wood plastic composites have emerged as a material with many uses especially in the construction industry. The combination of wood and thermoplastics form wood plastic composites which have unique mechanical properties which have been researched extensively. The usage of wood plastic composites as a building material has raised the concern on the thermal properties and flammability of wood plastic composite which this study is focusing on. The main reason behind this concern is due to the flammability of each separate material in the composite and if the combined composite is as flammable it could be catastrophic when used in the construction industry. The content of this study focuses on gathering previous research on the governing topics and forming better understanding on the thermal properties and flammability of wood plastic composites.

Wood is a solid material, and it is derived from shrubs and trees. The wood is composed of cellulose (40% to 50%), hemicellulose (15% to 25%), and lignin (15% to 30%). It can be classified as (i) softwood or (ii) hardwood, and some of the advantages include biodegradable nature, non-corrosive, high load-bearing capacity, etc. Though the wood has many benefits, it has a significant disadvantage of porous nature, poor resistance against abrasion, and delamination. Furthermore, the wood is susceptible to (i) light, (ii) heat, and (iii) ultraviolet (UV) radiations. Thus, this chapter examines that the issues related to the tribological behavior of wood plastic-based composites. The term ‘tribology’ is dealt with the subject of (i) wear, (ii) friction, and (iii) lubrication characteristics. Furthermore, any tribomaterials are developed by analyzing their friction and wear characteristics by varying (i) applying a load, (ii) sliding velocity, (iii) sliding distance, and (iv) working temperature.

Wood polymer composite (WPC) is an environmentally friendly and sustainable material which has been exploited in the filed such as building and construction marine, packaging, house wares, aerospace and automotive industry. In recent years, there is a rapid growth in the usage of WPC as it possesses low maintenance cost. The properties of WPC depend on the interaction between wood and polymer. WPC has characteristic water uptake and swelling properties. A knowledge of water absorption and swelling behaviour property of WPC is essential to tune the WPC for different application. Hence, in this chapter we give a brief outlook about the water absorption and swelling behaviour of wood plastic composites. The effect of processing method, fiber content, orientation, matrix type, wood content, coupling agent, crosslinking, immersion time and temperature on the water absorption and swelling of WPC is briefly described. This chapter also discuss different swelling test of wood polymer composite.

Long-term weathering performance of polypropylene based wood plastic composites manufactured using a combination of extrusion and injection molding processes were evaluated. The effect of micronized titanium dioxide (TiO₂) content (3-6-9 wt%) on the color changes (Spectrophotometer), selected mechanical properties, surface morphology (SEM), and surface chemical changes (FTIR) of the neat (PP) and composites samples (PP/WF) were investigated after 6, 12, 18 and 24 months of weathering in the City of Izmir, Turkey. Addition of TiO₂ has reduced ∆E^* and ∆L^* values from 35 to near 10 indicating higher resistance to weathering. Morphological study showed that distinguishable micro-cracks were present on all 12 months weathered samples (without TiO₂). Presence of TiO₂ has increased the number of cracks but they were less severe due to the reduced length and depth. After 24 months of weathering, large cracks and delamination of PP layer were present on the surfaces. However, this phenomenon was also severe and less pronounced in groups having TiO₂ compared to others. FTIR study showed that TiO₂ slightly reduced the intensity of the all bands associated with weathering process. Study showed that TiO₂ can be utilized to some extent in the formulations of PP and PP/WF against detrimental weathering effects.

Widespread environmental awareness to achieve product sustainability has triggered great efforts to use more environmentally friendly materials in product design. One of the most promising solutions to meet these needs is the use of wood and plastic composite fibers to reduce reliance on synthetic fibers as reinforcement and fillers for polymer composite construction. Much effort has gone into fully quantifying the benefits of Plastic Wood Composites (PWC) for various applications such as automobiles, building materials, and household appliances. The Life Cycle Assessment (LCA) is one of the efforts of personal watercraft whose main objective is to determine the potential environmental impact of the use of these materials on the environment as a whole. One of the main benefits of conducting life cycle analysis is the ability to provide a more holistic view of environmental impacts, covering the entire life cycle of the product, from the extraction of raw materials to the end. life, allowing justified decisions on the suitability of the use of PWC for specific applications that must be scientifically made. This chapter provides an overview of the LCA method, followed by a description of its uses with PWC in various applications. The advantages and disadvantages of the LCA method compared to personal watercraft are discussed, as well as a final conclusion on the future directions of the LCA application for personal watercraft.

Awareness against sustainable manufacturing and materials raised globally due to global warming and climate change. Sustainable materials are environmentally benign materials, and which produce lesser impact than conventional materials. Using Life Cycle Assessment (LCA), environmental impact can be computed for product or process. In this chapter, the environmental impact is calculated using LCA methodology for wood-based biocomposite panel. The environmental impact was calculated for Wood chips, and Poly Lactic Acid (PLA) based biocomposite panel. SimaPro software was used to analyze the environmental impact. Two impact assessment methods (EcoIndicator 99 and CML) were used to find the environmental burden of the wood-based composite. And finally, the environmental impact of the wood-based composite is compared with commercially available wood-based panels.