One More Way That Hemp Plastic Could Save Our Lives

Without a return to a vastly simpler existence, there's no way we can get rid of them any time soon. But there is only so much the planet can stand - and with plastic waste choking the oceans, trees and soil, we must find sustainable and environmentally acceptable alternatives soon. Even though the very first plastics were of organic origin, synthetic plastics became the standard, and rapidly became seen as indispensable.

Due to their versatile nature, there is a huge amount of money to be made in plastics, and it is much easier to slap a patent on a synthetic product than one based on plants growing abundantly in nature, as the multinationals have been demonstrating for years. Even the biggest global businesses are beginning to recognize the potential for bio-plastics, but the impetus needs to increase still further before we see universal uptake of sustainable technologies. The more publicity that we can bring to these innovative hemp researchers, the more we at SSUSA feel we are doing something to assist their efforts.

Hemp Hoodlamb's bullet-proof men's jacket (© gabe mcintyre) Over the last decade or so, advances in hemp plastic have meant that a wide selection of products is now available, and research into further potential uses is picking up pace in many countries of the world. In the USA, not all possibilities are being as explored as they should, due to a combination of inter-related factors - domestic hemp production remains illegal, so while it is possible to import hemp materials and products, prices remain high, supplies inconsistent and public awareness minimal.

But the small number of innovative organizations out there that are investing heavily into hemp research is slowly growing, and with every new piece of research a new incentive emerges for others to join in the movement. With time, more and more sectors of industry will become aware of the advantages of hemp plastic, and with consumer awareness at an all-time high, eco-friendly ethics are becoming the safest choice for companies wishing to maintain their profit margins.

The most significant developments have arguably been in the field of composite plastics, where a reinforcing fiber (in this case, the 'bast' fibers of the hemp plant) is mixed with a resin, such as unsaturated polyester, or organic plant-based resins to form a wholly 'natural' plastic. Plastics formed in this way can be thermoplastic (i.e. upon repeated heating, they can be molded and remolded into shapes that will be retained when cooled) or thermosetting.

The latter type of plastics is formed at high temperatures, but if reheated retain their characteristics and cannot be remolded. Some of them are capable of withstanding intense and prolonged heat, severe impacts and exposure to extremely corrosive or harmful chemicals. Their characteristics depend on the resin used, but more importantly, the fiber used to provide strength and durability. These fibers, when not sourced from organic materials (such as hemp or flax), are usually created in the laboratory in the form of synthetic polymers - nylon, acrylic and carbon fiber are common examples.

The Kevlar fiber in its unprocessed state (©Cjp24) Kevlar, or poly(p-phenyleneterephtalamide), is a synthetic 'para-aramid' polyamide fiber developed and patented by DuPont in 1965, which was revolutionary in the world of polymer research at that time. Aramids are the class of high-strength, highly heat-resistant synthetic polymers mostly developed for military and aerospace applications; para-aramids have the best strength-to-weight ratio of them all.

However, it was while attempting to develop a strong, light material (to be used as a substitute for steel in racing tires) that researchers found that in a solution of concentrated sulfuric acid, the monomers 1,4-phenylene-diamine and terephthaloyl chloride take on a polymerized liquid crystal form. When spun, this produces a fiber, around five times stronger than steel, that does not break in the way that nylon and other synthetic fibers do - due to strong, web-like inter-molecular bonds between the polymer chains, which cause them to form ring-like structures.

Furthermore, the propensity for 'aromatic stacking interactions' gives the fiber incredible strength and consistency: this is the tendency for said polymer rings to respond to molecular forces during processing and grow in an even, cylindrical shape - somewhat like a stack of coins. The resulting ultra-thin, ultra-strong Kevlar fiber can be woven to produce textiles, or layered with resin and thermoset to form composite plastics, all of which show remarkable resistance to tearing and cutting as well as to fire and heavy impacts.

“With plastic waste choking the oceans, trees and soil, we must find sustainable and environmentally acceptable alternatives soon„ The new fiber had astonishing potential as a substitute for steel and more, and further research was undertaken immediately. There are now several grades of Kevlar on offer in the form of various papers, yarns and fibers.

These have a number of uses extending beyond the original use in car tires, and are the best-known current application of body- and vehicle armor to cover ropes, cables, brake linings and sporting equipment. Kevlar is also very stable in extremes of temperature - especially sub-zero levels - and has very low thermal conductivity, meaning that it is an excellent insulator and can be used in fire-proof clothing, as well as heat-containing linings for aircraft.

However, Kevlar is generally expensive to produce due to the fact that concentrated sulfuric acid is costly, and dangerous to work with in an industrial setting. A further disadvantage is its low resistance to sunlight and tendency to degrade under UV light, meaning that additional protective measures are often needed.

Lower-cost alternatives for Kevlar are constantly being sought. In at least one of its uses, in brake pads, replacing Kevlar with hemp composite plastic would reduce the cost by a factor of around fifteen. Kevlar is used here, ironically, as a more benign alternative to asbestos, which produces a toxic dust; hemp plastics offer a cheaper and more sustainable option.

In the automobile industry in general (but especially in Europe where there is a long tradition of hemp cultivation, more relaxed laws and a much cheaper and more consistent supply) hemp plastic and fiber products are increasingly known and used. Hemp-reinforced plastics can have an impact resistance and tensile strength ten times that of steel, and thus are useful in manufacture of lightweight materials that can be used as automobile paneling (also for armored vehicles), as well as body armor and even powerboat hulls.

“With plastic waste choking the oceans, trees and soil, we must find sustainable and environmentally acceptable alternatives soon„ The fire-resistant nature of many hemp fibers and fiber composites also makes them particularly strong potential candidates for substitution of Kevlar when used for manufacture of protective clothing for firemen - and other fire-proof items such as fire-eaters sticks. However, such products are neither well-known nor widely-available, and it is clear there is much still to be done before hemp products replace Kevlar and other environmentally-damaging plastics.

The Kevlar fiber can also be woven into textiles, and in this manner can be used to make lightweight, discreet items of clothing that are not apparently armored but are capable of protecting against otherwise highly dangerous impacts, such as those from projectiles. These textiles are used in a wide variety of protective or industrial clothing due to their fire and chemical-resistant properties. Researchers at the Georgia Institute of Technology are even investigating the potential to create electricity-generating clothing by interweaving zinc oxide nanowires between the Kevlar fibers.

But it seems that everything Kevlar can do, hemp can do just as well, and maybe better. While remarkably strong in itself, the raw hemp fibers can also be treated in various ways to alter the characteristics of the finished fiber. At least one treated hemp-fiber product is already available, Crailar, that demonstrates remarkable tensile strength, very good strength-to-weight ratio, and high durability (as well as an almost silk-like texture when woven into textiles). It is produced by washing the hemp fiber in a 'patented enzymatic bath', which increases its softness and suppleness.

The fiber can also be used as a basis for composite plastics, and due to the thermo-regulating properties of hemp, is useful in extremes of temperature. Although the company behind Crailar, Naturally Advanced Technologies, is not actively researching bullet-proof clothing themselves, the fiber demonstrates many of the necessary characteristics.

Due to its fire-proof nature, Kevlar has many uses - as seen here with these fire-stick wicks. (© phidauex) Kevlar has a very high tensile strength-to-weight ratio, making it ideal for uses such as this sailcloth. (© henry heatly) Interestingly, silk itself was used in some of the earliest bullet-proof vests, and is also being trialled in modern Thailand as a low-cost alternative to standard bullet-proof clothing for police.

The silk of a particular Black Widow spider is even being used in US research into Kevlar alternatives, as it appears to be even stronger and lighter. However, these spiders are rare, and silk farming in general is often less than eco-friendly. Hemp is abundant, fast-growing and (usually) cheap, as well as comparing to or out-performing silk in many aspects, so as a sustainable option it is clearly favorable.

However, the silk vests tested so far have reached up to level III-A, a reasonable level of protection against handguns for an urban or police application, and hemp fiber technology still has a little catching up to do. The Amsterdam company HempWorks has an in-house clothing label, Hemp Hoodlamb, who offer a level II-A bullet-proof men's jacket, tested with shots fired from a Glock 9mm, a .22 and a .357 Magnum.

This discreet item has a fairly low protection rating due to the thin layer of polymer textile over the standard shell of the jacket, so is obviously more suitable for an urban setting than for high-risk police work or warfare. These jackets still represent a significant advance in hemp fiber research - and demonstrate major potential for the future. Costs of such discreet bullet-proof clothing, even those based upon traditional plastics, can easily run into the hundreds or thousands of dollars.

While clothing based upon hemp is still expensive, it is competitive, and it would be expected that costs will continue to fall as the industry continues to pick up pace. “Ultra-thin, ultra-strong Kevlar fiber can be woven to produce textiles, or layered with resin and thermoset to form composite plastics„ Since their discovery in the 19th century, much research has gone into the field of thermosetting composites, such as those made from Kevlar.

There are countless different applications, in innumerable different areas of industry: construction, vehicles, fashion and jewelery, packaging, sports equipment; as well as manufacture of weaponry and defensive items. Hemp composites have been shown to be equally strong, and in many cases stronger, than current industry standard materials - and not just Kevlar but also glass- and carbon-reinforced composites (which are currently used in pretty much everything you or I own).

Many of these everyday plastics have a truly terrible environmental track record - they require lengthy, hazardous and often costly production processes, are mostly non-biodegradable, often 'disposable', and are filling up landfills and the ocean everywhere one looks with harmful detritus that will never decompose.

Therefore, seeking alternatives to these current standards is imperative, and the closer we look at natural composites, the more necessary it seems to make them the norm - and fast!   While most lovers of Cannabis have no desire to see the plant used for military or law-enforcement purposes, the potential for hemp in such a massive sector of industry simply cannot be ignored.

The fact that the industry is worth so much money is in itself significant in that there is almost unlimited funding available from the top multinationals for research and development. Car companies such as Honda, Chrysler and Mercedes are all using hemp plastic as we speak, and are likely channeling further capital into R & D.

The question now is, who will be the next industry giant to take up the challenge of making hemp economically viable? Certain stalwarts of the plastics industry would do well to pay attention to the growing hype around hemp. It would be most fitting if a hemp-based plastic could knock DuPont's product off the top spot. Given the rabid hostility demonstrated by DuPont towards the innocent hemp plant since the 1930s, it's only right that we actually give them a reason for hating.