What are the properties of cork fiber?
Cork is completely recyclable and even biodegradable material. Being natural materials lets see what are the physical and mechanical properties of cork material:
• Light-weight: Cork is a lightweight material i.e. it is 5 times lighter than water. This is because 90 percent of its volume and 50 percent of its weight is made up of microcells which trap air and make it lighter. The range of specific gravity of cork is between 190 to 250 kg/m3.
• Strength: Cork material poses high mechanical strength and retains its strength even both in very low temperatures as well as high temperatures.
• Flexible and compressible: The cork material can retain its structure after the application of force. This property of cork is because of the flexible nature of the cell membrane of cork. As already mentioned that 90 percent of cork volume is made from microcells that trap air. Hence, whenever high pressure is applied on cork, these microcells get compressed by displacing the air and the volume gets reduced. As soon as the pressure is removed cork returns to its previous shape.
• Durability: Cork is known to be one of the most durable natural materials which do not get aged as time passes. Hence it doesn’t lose its properties even after impregnation procedures.
• Impermeability: Around 39 to 45 percent of the cork is made up of suberin. The water repellent property of suberin present in cork does not allow it to absorb water hence it never sinks and floats on the surface of the water. It also provides strength and heat insulation property to cork material.
• Resistance towards chemicals: One of the unique properties of cork is that it is chemically inert which means that cork does not react or gets destroyed when it comes in contact with any type of liquid or gases. The taste and the odor of cork material are neutral in nature.
• Resistance to biological corrosion: Due to the absence of protein material which is prone to degradation and the presence of natural tannins, the cork material is resistant to biological corrosion. The main reason for biological corrosion is moisture. But since the cork is waterproof in nature hence it does not provide room for the growth of fungus and molds. Cork materials are also resistant to mildews.
• Thermal insulation: When compared to other material, cork material has a very high specific heat capacity which helps to retain its insulation properties over a very large range of temperatures. The range of thermal conductivity of cork is between 0.037-0.040 W/(mK). The product made from Cork material neither transmits heat nor absorbs body heat i.e. it has weak thermal conduction. Cork material stabilizes the air temperature and humidity.
• Flame Retardant: Cork material has high thermal inertia hence normally the products which are made from cork are flame retardant and do not catch fire easily. But this property also depends on several other factors like cork dust is highly flammable because the cell structure breaks down.
• Anti-static: Cork material has an anti-static property which means that cork doesn’t get electrified. Since the electric charge does not get accumulated on the surface of the cork hence dust also does not get attracted to the surface. This property of cork makes it hypoallergenic and helps to keep the surface clean.
• Anti-vibration property: Cork material has a special structure that does not allow the sound to echo or transmit rather it absorbs sounds and vibrations. Airborne sound and its impact are suppressed by the special structure and flexible property of cork. 30 to 70 percent of tonnes of the frequency range between 400 to 4000Hz can be absorbed by cork material.
• Easy manufacturing: The manufacturing of cork material only needs a few sawing, cutting tools and skilled workers. The presence of the natural adhesive makes cork easy to stick with baking fabric and different surfaces.
• Nontoxic: Cork is a natural material that does not contain any type of toxic material. Hence it is skin-friendly and does not cause any type of allergies.
• Biodegradable: Being produced from organic sources and self-generating trees, the cork material is 100 % biodegradable and compostable in nature. Its manufacturing process does not create a negative impact on the environment.