Each year, innovations in hemp plastic technology hit the market and many companies are incorporating hemp plastics into their products. Hemp is proving to be a clean alternative to the highly polluting plastics that are damaging our environment. There are various types of hemp plastic; here, we will briefly take you through how these plastics are produced.
Why is there a need for an alternative to plastics?
There is no doubt that we are experiencing a major environmental crisis that takes many forms. Human beings have followed a non-sustainable development model for which we are now suffering the consequences. The already perceptible change in climate, the significant loss of biodiversity and, of course, the pollution of the soil, the air and the seas are some examples of the damage we have caused to our environment.
Take our seas and oceans, for example, which we have turned into a gigantic repository of rubbish that threatens marine ecosystems. According to Greenpeace, every second more than 200 kilos of plastic are dumped into the world’s oceans and seas, which is equivalent to more than 8 million tonnes of plastic waste a year.
In addition, more than 1 million seabirds and over 100,000 marine mammals die annually because of the damage caused by plastic, chemical and oil waste to the marine environment. Although some of these residues, which accounts for 80% of all sea pollution, can degrade and disappear in just over six months, many others take several hundred years to do so.
Meanwhile, plastic waste, including “microplastics”, leaves a great deal of air, sea and land pollution. A team of scientists recently demonstrated that these microplastics are dispersed through the air and reach remote natural areas, with concentration levels similar to those found in large cities.
International governments and environmental organizations have already begun to act to stop this serious global ecological threat. However, the targets set in the various international agreements for 2030 and 2050 seem somewhat unattainable for many countries and regions.
We need urgent measures to stop plastic pollution, and each of us must try to do our part to innovate, change mentalities and respect the environment. Our lives and future depend on it.
Hemp: A raw material returns from the past
Hemp is the plant that has the potential to help us reinvent the future of plastic and other materials. It is a clean, ecological, sustainable and renewable alternative. And it can replace the use of polluting materials in the production of goods in many fields, such as construction, automobiles, fashion, design, sports, and many others.
But hemp is not a new resource that responds to a specific ecological trend. Hemp is a raw material that returns from the past to help us rethink the future. For millennia, it has been used for its nutritional properties and multiple health benefits, and it has served as a raw material for countless products such as food, textiles, and medicines.
Hemp is among the crops that creates more biodiversity in its surroundings. Its cultivation allows us to obtain at low cost three raw materials: the seeds, the fibre and the pulp. Fibre has always been the most used for its excellent qualities, as it is the most resistant, absorbent and durable fibre of vegetable origin.
Reinventing the future of hemp plastics
It is becoming increasingly easy to find products aimed at various sectors made from vegetable fibres, such as flax, coconut and, of course, hemp. The aim is to replace the polluting materials that have been produced for decades. As we have said, hemp can replace many of these materials, such as plastics, thus helping reduce pollution worldwide.
The use of hemp not only entails an ecological benefit. It also improves the quality and performance of the products containing it. For instance, hemp fibre has long been used, instead of fibreglass, to make surfboards as it makes them much lighter, more flexible and resistant, and gives them sensational grip and buoyancy.
Thus, with increasing frequency each year, innovations in hemp plastic technology come onto the market. Today, even some of the largest automobile companies such as BMW, Mercedes and Bugatti incorporate hemp plastics in their products. The latest Porsche model, for instance, the 718 Cayman GT4, incorporates hemp fibre panels manufactured by the Dutch company Hempflax.
In short, bioplastic materials, including hemp, offer significant advantages for the environment. Because they are not made from fossil fuels, they do not produce carbon dioxide when decomposed. In addition, most of them are biodegradable. Everything indicates that they could be a very important part of solving the climate crisis.
5 types of hemp bioplastics and how they are used
1. Hemp cellulose
Cellulose is the most abundant organic polymer on Earth, and is an integral part of the cell walls of plants and many algae species. Although cellulose is mainly used to make paper, it is also used to make a wide range of different plastics, including celluloid, cellophane and rayon.
The first plastics were made from organic and non-synthetic materials, and cellulose was then a key element in the nascent plastics industry. Today, bioplastics have again attracted great interest for their diverse environmental benefits.
2. Cellophane, rayon and celluloid
Celluloid is obtained by producing nitrocellulose (cellulose nitrate) first, which is mixed with camphor, a widely used plasticizer, to yield a dense, solid thermoplastic that can be easily moulded when heated.
Hemp cellulose can be extracted and used to make cellophane, rayon, celluloid and a variety of related plastics. Hemp is known to contain around 65-70% cellulose, and is considered a good promising source, largely due to its relative sustainability and low environmental impact. By comparison, wood contains around 40% cellulose, flax 65-75% and cotton up to 90%.
Hemp grows faster than most tree species, and requires fewer pesticides than cotton or flax. However, a significant amount of fertilizer is required when grown in some soils, and it also needs a relatively large amount of water.
3. Other products made from hemp cellulose
Cellulose can be used to manufacture a wide range of plastics and related substances. The difference in physical properties is largely due to the length of the polymer chains and the degree of crystallization.
Cellulose is extracted from hemp and other fibre crops using different methods. The raw pulp can be hydrolysed, i.e. separated into its component parts by adding water at 50-90° C. It can also be immersed in a weak acid solution to separate the crystalline sections from the amorphous ones, thereby producing cellulose nanocrystals.
Extra heat and pressure can also be applied to it to produce an interesting form known as nanocellulose. This is a “pseudo plastic” that resembles a viscous gel under normal conditions, and becomes more liquid when agitated or stressed.
Nanocellulose or microfibrillated cellulose (MFC) has a wide variety of potential applications. It can be used as a reinforcing material in plastic compounds and as a highly absorbent agent to clean up oil spills or oil slicks. It can also be used to manufacture sanitary products, and as a low-calorie stabilizer in food technology.
Zeoform, an Australian company, offers a cellulose-based plastic material manufactured using its own patented process, which includes hemp.
Through their technique, cellulose fibres are converted into a mouldable material that has a high industrial strength for an unlimited variety of products. This material is advertised as 100% non-toxic, biodegradable and recyclable as it can be composted and offers a very interesting form of carbon capture and sequestration.
4. Hemp-based plastics
Composite plastics consist of a polymer matrix, which may be based on cellulose or a range of other natural or synthetic polymers, and reinforcement fibres, which in turn may be of natural (and mainly composed of cellulose) or synthetic origin.
Natural polymers include tar, shellac, tortoiseshell, and many tree resins, while natural fibres include jute, sisal, cotton, and flax. Traditional inorganic fillers include talc, mica and fiberglass.
Biocomposites generally have at least one major component of organic origin. Although 100% organic plastics exist, most contain some synthetic elements. Typically, a natural fibre is blended with a synthetic polymer and then labelled as biocomposite. The various combinations of natural fibres and polymers that can be used to make bioplastics vary greatly in density, tensile strength, stiffness, and other aspects.
These factors can be modified during the manufacturing process to create suitable products for a wide range of applications. The latter include the fabrication of building materials, furniture, musical instruments, boats, car panels, biodegradable shopping bags, and in medicine, biocompatible “supporting structures” in bone tissue reconstruction.
Hemp fibres are used as reinforcement in composite materials and are known for their tensile strength, in particular female plant fibres. Male plant fibres are finer, softer, and often more durable, but they are also less resistant.
A 2003 study of natural fibre-reinforced polypropylene (PP) composite materials showed that hemp, kenaf and sisal had a tensile strength comparable to that of traditional fibreglass composites, and that hemp outperformed its competitors in impact resistance.
In 2007, another study on PP composites reinforced with hemp fibres, in this case by using a material known as malleated polypropylene (MAPP), showed that overall stress and mechanical properties were increased by up to 80% compared to traditional glass fibre composites.
5. Pure biocomposite materials made from hemp
Several biocomposites or biomaterials have already been developed entirely from organic substances, including hemp which is used as a filling material.
In a study conducted in 2003 on the tensile strength of hemp fibres, it was shown that when alkalized with dilute sodium hydroxide (NaOH) in concentrations of 4-6 %, they exhibit greater tensile strength and stiffness when combined with the liquid polymer matrix of the cashew shell in the manufacturing of biocomposite plastics.
A group of Korean researchers announced in 2007 the creation of a biocomposite produced from organic polylactic acid (PLA, an important biodegradable thermoplastic polyester) reinforced with hemp fibres. They also discovered that treating hemp fibres with diluted alkali increased their tensile strength. Biocomposite materials showed higher strength and stiffness than plastics containing only PLA.
In 2009, a group of researchers from Stanford University announced the development of a hemp fibre reinforced composite made from biopolyhydroxybutyrate (BHP). Materials made of hemp and BHP are strong, soft, attractive and durable enough to be used in construction, furniture and flooring materials.
In a 2014 study on the development of fully biodegradable composite materials using poly (butylene succinate) (PBSu) as a polymeric matrix and hemp fibres and hemp shives as a filler, it was found that tensile and impact strength are both affected by the type and amount of filler used. PBSu/Hempagramice compounds had higher biodegradation rates than PBSu/Hemp fibre compounds.
Towards a sustainable future
Clearly, research still has a long way to go before the best sustainable alternatives to petroleum-derived plastics are achieved. However, new research is accelerating as governments and nations around the world become more aware of the need to drastically reduce the use of petrochemicals. And hemp is increasingly being recognized as having tremendous potential in our natural ‘toolbox’ of promising crops for bioplastics.