Part II: Organic Fillers in Plastic Hardware
Could organic materials be the future of plastic manufacturing when the oil runs out? Since plastics are petroleum based, in the future will plastics no longer be available? Imagine the profound impact this would have on our society. How will we manufacture cell phones or computer casings, or even our clothes, shoes and furniture?
Organic materials have been used in plastic manufacturing for a long time. The first truly synthetic plastic was Bakelite, developed in the early 1900s in New York by Belgian born American chemist Leo Baekeland. Its first commercial use was in the gearshift knob for a Rolls Royce in 1916. Today Bakelite is commonly called phenolic resin. It is made by combining phenol and an aldehyde, both of which are organic compounds. When pressure and heat are applied, polymerization occurs. Additionally, Bakelite contains wood bark flour and is a thermosetting phenol formaldehyde resin with excellent dielectric properties. It was used in printed circuit boards for its non-conductivity and heat-resistance. It was also used for a wide variety of consumer products including billiard balls, handles for pots and pans, plugs for electronic devices and jewelry.
Organic materials are used in plastic manufacturing both for making the base resin and as filler materials. Organic fillers include nut shell flours, wood flours, rice hull flour, wheat chaff, flax hulls, corn cob flour, chicken feathers, cork flour, clam shell flour, and many more. Additive organic fillers or bio-fillers are commonly used in polymer composites to extend the base resin. These polymers include polypropylene, polyethylene and PVC. Organic fillers have several advantages such as low density, low cost, and ease on processing equipment. However, natural fibers do tend to degrade in higher temperatures thus composites with these fillers are limited to plastics with low melting temperatures. Natural fibers in a thermoplastic composite also tend to lower the impact strength.
In the U.S., organic materials are often used as additive fillers in wood-plastic composites (WTC) for construction materials. For example, Composite Technology Resources in Quebec has this kind of product made of 60% rice hulls and 40% recycled high-density polyethylene. In both the U.S. and Europe, bio-fillers are used in automotive applications including interior panels, dashboards, and car roofs. For example, rice hulls from farms in Arkansas are used replace talc based fillers in the polypropylene used in an electrical harness in the 2014 Ford F- 150 truck. The Ford F series has been America’s best-selling truck for over 35 years. In the 2015 Volkswagen Golf, the front end carrier which provides support for head lamps, the engine cooling system, and other driver assistance systems are made from 50% polypropylene and 50% flax fibers.
Organic compounds can also be used to manufacture the base resin. We have already considered the organic materials that make-up Bakelite (phenolics). Lignin is another source of biopolymers. Lignin is a complex organic polymer found in the tissues of plants and trees.
It is the substance that causes the stalks, twigs and trunks to have shape and form. It is one of the most abundant organic polymers on Earth, second only to cellulose. Lignin is a by-product of many industrial processes, including pulp mills, biofuels, and chemical or pharmaceutical production from plant materials. The science of making plastics from lignin has not yet been fully developed and promising research is on-going around the world, but there are examples of these bio-plastics in current commercial use. Pure Lignin Biotechnology Ltd. in Canada markets lignin bio-fillers that can be added to polypropylene and polyethylene, making up as much as 20% of the finished polymer. According to the company, the resultant polymers exhibit improved tensile strength and an increase in flexural modulus. cycleWood Solutions, LLC, a start-up from the University of Arkansas MBA program, markets single use plastic bags made from a lignin based 100% biodegradable and compostable thermoplastic, called XylomerTM. It can be made into cups, plates, and bags that break down into humus in approximately 180 days.
As petroleum reserves become depleted and the demand for recyclable bioplastics increases, we could be seeing a lot more of organic materials both as fillers and as base resins in the plastic manufacturing industry.
What’s your vision for the future of plastic manufacturing? Let me know in the comments section below.
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