Ever wondered what is the primary compound that makes cardboard, printing papers, magazines, newspapers, packaging, decorating items and even clothes? Let’s know more about it.

What is Cellulose?

Cellulose ((C₆H₁₀O₅)_n) is the most abundantly available organic polymer on earth.  It is an important component of the cell wall of plants and algae. It is therefore readily available in the natural environment. The cellulose content varies from plant to plant and that determines their usage. 

Cellulose has no taste, it is odorless and non-toxic material. It has a white color at pure state. It is insoluble in water but it shows swelling with water. The thermal stability of cellulose is relatively high, it is stable up to a temperature of 200 to 300 degree Celsius.  High tensile and compressive strength is another characteristic of cellulose. These properties make cellulose suitable for different uses.

Although the compound was discovered recently, these amazing properties of cellulose were known to man for thousands of years. Over the years, new technologies have tried to make the best use of cellulose. However, we still have a long way to go. Let us understand why.

Processing

Cellulose is primarily used in the manufacture of products like paper, cardboard and textiles. We try to list a few important steps in the journey from cellulose to its final form as we see it. First, spongy cellulose fibers called pulp are separated from the raw material. Then the pulp is spread into sheets, pressed and dried to form paper. Paper is further cut into strips, twisted and woven together to make a fiber.

Fiber is also readily available from natural sources such as sheep’s wool, flax, cotton and silk. These short fibers are spun into longer filaments to make the yarn. The characteristics of spun yarn depends on the amount of twist given to the fibers during spinning. A fairly high degree of twist produces strong yarn while a low twist produces softer, more lustrous yarn. Later, yarn is used to make textiles using a variety of processes, including weaving and knitting.

Current problem

The world fiber demand continues to grow at an unprecedented pace. Unfortunately, this demand is being met by cheap but environmentally disastrous petroleum based polymers. Fabrics made from these polymers currently end up in landfills and oceans and take years to degrade besides contributing to carbon emissions.

Fashion industry is currently considered to be one of the most polluting industries in the world. Recent studies claim it to be the second most polluting after oil and gas industry. Apart from petroleum based products that currently dominates this market, contribution also comes from age-old unsustainable practices. Cotton being one of the main sources of cellulose accounts for 2.6% of global water use. On average, it takes almost 10,000 litres of water to produce one kilogram of cotton fabric, meaning it takes about 8,000 litres for a pair of cotton jeans. Unfortunately, cotton is mainly produced in regions where there is a shortage of water supply. When the available water is used for cotton irrigation, the situation with regards to food worsens.

Another main raw material in the textile industry is wood or bamboo. The kraft process is used to separate cellulose from wood. The process requires the use of Sodium Sulfide and processing plants can release odorous products and in some situations produce substantial liquid wastes. It is the dominant method for producing paper. Roughly speaking, wood is chopped and treated by additives which break down the fibers into a pulp. The pulp is then treated in a process called viscose process which converts the cellulose into usable soft fibers. Though highly toxic, carbon disulfide is used in the production of viscose. With production facilities often located in developing countries, concerns for worker safety continue.  Despite environmental impacts of by-products and volatile harmful solvents, the viscose process is still the most important method for shaping cellulose. 

Possible solution

There is a strong need for the use of sustainable products and manufacturing processes in the textile industry. Manufacturing processes that do not use hazardous chemicals, cause less CO₂ emissions, use less water and land should be promoted. Fortunately, there have been some promising steps already taken in this direction. Recently, fiber from Hemp is seen as a promising alternative to cotton or wood because of several reasons. Hemp requires less to no pesticides or fertilizers. It requires less water, grows extremely fast and yields more fiber than cotton. Hemp renders the soil fertile for subsequent crops.  Additionally, Hemp fiber is strong and of a superior quality. Fabric made from hemp is breathable and hypoallergenic thus suitable for people with sensitive skin. 

Apart from these recent advances, research has also focussed on recycling cellulose fabrics. Instead of using cellulose from plants, the cellulose can be recovered from used clothes, wastes from the textile industry. These wastes can be treated to remove non-cellulosic materials like buttons, zips and even polymer blends. Later with a series of chemical and mechanical treatments cellulose can be recovered in the form of cellulose carbamate. Cellulose carbamate can be stored in containers in the form of powder and is used as needed. 

Several other promising technologies have emerged in last few years.  Algae Apparel is a company that uses antioxidants, vitamins, and other nutrients to create an eco-friendly fabric from algae which is a natural, abundantly available source of cellulose.  Bananatex claims to be the world’s first durable, waterproof fabric made purely from Banana plants without any chemical treatments. Qmilk a silky fabric, is produced from milk that is no longer fit for consumption as food or tradable. Nanollose, a company based in Australia creates garments from liquid coconut waste.

As these promising technologies are being developed, it is important that they are developed in a manner that their benefits, vis a vis cotton and other polymers are proven with life cycle impact data. Otherwise inefficient manufacturing process chains that are carbon intensive from energy usage will be promoted.

Takeaway

While a number of bio-based raw materials like cotton, wood are currently available, the production technologies are not sustainable and therefore not a suitable option for meeting the demand. The need of the hour is alternative fiber and technologies that do no or less harm to the environment. Technologies that are environmentally friendly and at the same time economical is the right way forward. The use of cellulose as raw material together with new technologies offers substantial benefits over existing practices. Cellulose is therefore one of the answers to the question of global warming.