Bio-composites — composite materials made from natural fibres and/or bio-based resins — are increasingly prevalent and have the potential to become the material of choice in the future. Their popularity is largely due to rising environmental concerns but can also be attributed to their versatility and excellent mechanical properties. Kathrin Schilling, Founder and Director, BioPowder.
According to Future Market Insights, the global bio-composites market is expected to increase at a robust CAGR of 16%, from $25bn in 2021 to $128bn in 2032. A key factor driving this growth is the materials’ environmental sustainability. Made from renewable resources such as natural fibres, bio-composites create less of an impact on the environment than traditional composites that are derived from fossil or non-recyclable raw materials.
The incredibly useful olive
A raw material that has been gaining wider attention of late is the olive pit, a by-product from the olive oil mill. Olive oil manufacturing involves compressing of the olive (as a whole), which produces a solid residue of pulp, peel and fragmented pits. In the past, raw olive pits have mainly been used for combustion.
According to the International Olive Council, an estimated 3.1 million metric tonnes of olive oil was produced during the season of 2021/22, up 2.9% from the year before. This translates to a massive amount of olive pomace left behind, which comes with certain disposal challenges because of its fat and salt content. Fortunately, innovation and new technology have emerged to recover this waste stream; olive pits can be upcycled into high-performance functional powders – fully circular additives with desirable properties for modern composite formulations.
Specialised machines are used to process fresh olive cake in a moist state, and olive pit fragments are separated from pulp and shell through a centrifugation process. The fragments are then mechanically cleaned, dried, screened and micronised into well-defined particle fractions. Through this complex treatment process, BioPowder recovers light beige powders that are neutral in smell and taste. These natural additives can be further functionalised, which makes them valued components for a variety of applications.
Proven applications of refined olive stones in composites
The base material of Olea FP – refined olive stones – essentially consists of cellulose, hemicellulose and lignin. It is an organic material that stands out from among other biomasses due to its unique properties. As a result, micronised olive stone powders are powerful functional fillers, reinforcing fibres and texture particles for composites. Incorporating them in material formulations comes with a myriad of possibilities.
In thermoplastic composites (e.g. PP, PE, PLA, PHA, etc.), functional olive stone powders are best incorporated in the pre-mixing or pre-heating stage of the compounding process. Smooth dispersion and particle stability ensure reliable functionality in both conventional and biodegradable compounds, and similar results can be obtained in 3D printing filaments.
In thermostable resin composites, Olea FP can add reinforcing properties besides unique texture effects. Bespoke grain sizes and coloured particles open new doors for bio-innovation, such as in the field of methyl methacrylate (MMA) composites or epoxy coatings.
Rubber is a major source of microplastics, mainly caused by the abrasion of vehicle tires or shoe soles. Filling synthetic rubber compounds with natural olive stone powders can help reduce the environmental impact while enhancing lifespan and mechanical properties.
And in cementitious composites such as reinforced concrete, olive stone powder can boost adhesion and surface finish of the material while adding strength and durability. The same goes for ceramic composites where the particles are also efficient porosity enhancers.
Benefits of olive stone performance powders for composite applications
Olive stone functional powders have been found to possess desirable mechanical properties that make it a potential candidate for use in the composites industry. Some of these benefits include:
Benefits of olive stone performance powders for composite applications
| High compressive strength and abrasion resistance | With a hardness of approximately 3.5 on the Mohs scale, particles made from pulverised olive stones can withstand wear and tear. This makes them particularly suitable for load-bearing composites with long lifespans. |
| Light weight | The density of olive stone powders is only a fraction of the density of inorganic fillers such as mineral or metal powders. This makes them a sought-after solution for lightweight composite parts that are often needed in the automotive, shipbuilding, or aerospace industry. |
| Thermal stability and insulation | Olea FP particles are designed for composites that are either manufactured at high process temperatures or made to be thermally resistant. In addition, they come with above-average heat retention properties that can be taken advantage of in construction composites. |
| Versatile surface functionalisation | Olive stone particles have a reactive surface, mainly consisting of hydroxyl groups. In composite applications, this effect can either be taken advantage of, or be suppressed by means of surface functionalisation. BioPowder offers made-to-measure surface treatments to ensure excellent compatibility of Olea FP with different chemistries. |
| Optimised carbon footprint | Olive stone particles are manufactured 100% mechanically, i.e. with electricity being the main required utility. The use of water is minimal and production does not generate any waste. Most remarkably, olive trees are among the plants that bind the largest amounts of CO2. Evidence shows that roughly 1.5kg of CO2 is produced per litre of extra virgin olive oil. However, an olive orchard can absorb up to 10kg of CO2 while growing the equivalent quantity of olives. |
Moving in the right direction
While there is still work to be done to ensure that bio-composites become the norm rather than the exception, there are signs that suggest that the industry is moving in the right direction. Life-cycle assessment has become an industry standard, and the carbon footprint of raw materials a central criterion for purchasing decisions.
Amidst the diversity of bio-composite formulations, manufacturers, and end users increasingly value compostability over industrial degradability and plant-based over fossil. With this in mind, BioPowder looks forward to partnering with companies to create a better world for future generations.
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