There has been stringent consumer awareness towards new products from renewable sources in the last few years. Green marketing, fresh opinions on recycling, social influence, and change of cognitive values have led consumers towards environmentally friendly results. Specifically, composite materials are being developed and redesigned to improve and adapt traditional products and introduce new products sustainably and responsibly.
This article examines and discusses the latest published trends in the context of natural fiber polymer composites while providing insight about natural fibers, polymers with highlighting their properties and applications
Natural Fibre-Polymer Composites
Natural Fiber Polymer Composites (NFPC) are composite materials consisting of a polymer matrix embedded with high-strength natural fibers.
Natural Fiber in Composites
Natural fibers are produced by plants, animals, and geological processes. They can be used as a component of composite materials, where the orientation of fibers impacts the properties. In the table below a few successful natural fiber evolutions are covered and compared to E-glass fiber in the property.
While designing composite parts, the choice of reinforcement is one of the first important decisions that need to be made. When choosing the right reinforcement for your application, you shouldn't ignore natural fiber as a viable option until they are ruled out based upon your requirements, as they bring sustainability to the overall production. However, there are a few key properties that you should take into consideration before making the decision. In the table below, some advantages and comparative disadvantages of natural fibers are highlighted.
Polymers: Thermoset and Thermoplastics
Another key component of the NFPC's is polymers that hold together the natural fibers. Usually, for structural applications, polymers can be categorized into two main categories, thermoplastics and thermosets.
The structure of thermoplastic matrix materials consists of one or two-dimensional molecules, so these polymers tend to get softer at a raised heat range and roll back their properties throughout cooling.
On the other hand, thermosets can be defined as highly cross-linked polymers which are cured using only heat or using heat and pressure and light irradiation. This structure gives thermoset polymers good properties such as high flexibility for tailoring desired ultimate properties, great strength, and modulus.
Thermoplastics are widely used for NFPC's as they can be reused multiple times whereas thermoset polymer either has to go through a chemical process or need to be incinerated to dispose of.
The properties of natural fiber composite differentiate from each other. According to prior reports, because of different kinds of fibers, sources, and moisture conditions. The performance of NFPCs relies on factors like mechanical composition, microfibrillar angle, structure, defects, cell dimensions, physical properties, chemical properties, and the interaction of a fiber with the matrix.
Since every product in the market has drawbacks similarly, natural fiber reinforced polymer composites also have disadvantages. The joints between natural fiber and polymer matrix are a problem taken into consideration due to the distinction in chemical structure between these two phases. It leads to ineffective stress transfer during the interface of the NFPCs.
Natural fibers include an active group named the hydroxyl group, making the fibers hydrophilic. NFPCs, weaker interfacial bonding occurs between hydrophilic natural fiber and hydrophobic polymer matrices due to hydroxyl group in natural fibers. It could produce NFPCs with soft mechanical and physical properties.
Parameters affecting NFPCs
Different factors can affect the characteristics and performance of NFPCs. The hydrophilic nature of the natural fiber and the fiber loading also impact the composite properties. Usually, high fiber loading is needed to attain the good properties of NFPCs.
Generally, notice that the rise in fiber content causes improving the composites' tensile properties. Another vital factor that considerably impacts the properties and surface characteristics of the composites is the process parameters utilized. To get the best attributes of producing composite, one should rigorously choose appropriate process techniques and parameters. The chemical composition of natural fibers also significantly affects the characteristics of the composite represented by the percentage of cellulose, hemicellulose, lignin, and waxes.
In this section, applications where natural fibers are already in use, where they can be used, and the future of their applications across many different industries are presented and discussed.
In the automotive industry, NFPC composites are eligible to side and front panels of vehicles as they are not primary structural components. The cost and weight of vehicles could be partially reduced when NFPC composites replace traditional glass fiber composites and aluminum in these components.
Civil engineering industries
natural fiber-cement composites for residential housing have been limited to exterior applications, such as siding and roofing. Additional protective coating material on these structures are demanded to avoid weathering attack.
Forcing function for adoption
Various industries such as automotive, energy, construction, and aerospace, among others, are being challenged by society and governments to make more environmentally toned products and reduce their dependence on fossil fuels. In this viewpoint, the European Commission administered a “European Guideline 2000/53/EG” to enhance automotive reusability to 85% in 2005 for a vehicle by weight. This percentage was escalated to 95% by 2015.
This type of codification is a significant driving factor in adopting natural fiber composites. Natural fibers are an attractive option for industries to meet socio-economic and environmental challenges in this scenario.
Furthermore, the use of natural fibers would create employment opportunities in rural and less developed areas, therefore assisting in attaining the feasible development objectives by the United Nations, namely diminishing poverty, creating comprehensive and sustainable industrialization and fostering innovation, creating sustainable cities and communities, and responsible production and consumption. Hence, natural fibers will play a vital role in the socio-economic development of our society.
Regardless of the fact that many factors affect the use of natural fibers as reinforcement in polymer-based composites, the renewability and cost competitiveness of natural fibers are still attractive to all business sectors to explore opportunities to replace traditional materials with natural fibers. The value of research in this direction is huge as many problems have not yet been solved. There is no doubt that designing NFRP composites and choosing their manufacturing process appropriately will help them to be one of the dominant structural materials in engineering industries in the future.
Addcomposites is the provider of the Automated Fiber Placement (AFP) system. The AFP system can be rented on a monthly basis to work with thermosets, thermoplastic, dry fiber placement, or in combination with 3d printers.