Wednesday, April 28, 2010
Thursday, April 22, 2010
Wednesday, April 21, 2010
Non-biodegradable plastics and polymers have become the material of choice in the modern world, and there is evidence of vigorous R&D activities to discover, develop, and commercially produce degradable biopolymers to replace them. But the reality is that biopolymers are still in the early stages of development and considering them as an alternative for the current commercial products is too improbable. Because biopolymers originate from plants, they can be utilized in sectors where they come in contact with the human body, such as personal hygiene/grooming, cosmetics, medical implant/devices, textile, and food markets.
The use of plastics in our everyday life is nearly boundless. Due to its low cost of production and versatility, no alternate emerging product is likely to replace the nearly ubiquitous presence of plastics. The current global production level is about 250 million tons and its growth will continue to be robust globally. Plastics are preferred as they are light, durable, resist deterioration, and the markets they cater to are extensive: food, textiles, furniture, electronics, vehicle parts, photography/videography, coatings, construction, enclosures, bottles/containers, and many more.
The most commonly used types of plastics are PO, PP, PS, PVC, PET, PC, PET, PU, polyacrylates, polyvinyl acetates, and polyamides. These synthetic polymers are typically made from the naphtha fraction of petroleum or natural gas; and are heavy pollutants as they are not biodegradable. We are living in a "throw away" society and as a result, millions of tons of plastics end up in landfills, the ocean, and the shores. Even if this practice were to stop today, plastic waste would continue to wash upon our shores for hundreds of years. This has significantly eroded the marine life, as millions of marine animals die each year; and there is clear evidence that this trend will escalate because the global thirst for these materials is on the rise.
Burning plastic wastes has not been an option either, as toxic gases such as hydrogen cyanide and hydrogen chloride are emitted. Attempts to accelerate biodegradation via additives such as chemicals, oxygen, and UV additives have not resulted in meaningful measurable reduction.
Thus, there is a dire need for the discovery of totally biodegradable polymers and it is not surprising to see that biotechnology has been the global focus. Biotechnology has been referred to as a series of enabling technologies that involve the applications of organisms to manufacturing and service industries to achieve environmental sustainability and stability. Touted as the major technology of the 21st century, one can observe that biotechnology is highly multi-disciplinary, since it umbrellas many scientific fields such as biology, microbiology, biochemistry, molecular biology, genetics, chemistry, chemical engineering, and biomedical engineering.
The total sunk-in capacity for biopolymers in 2009 was around 500 million lbs. These include polylactide acid [PLA] (NatureWorks, Galactic, Hycail BV); polyhydroxyalkanoates such as PHAs, PHB, and PHBH (Biomer, Procter&Gamble); polymers based on bio-based PDO (DuPont); cellulose polymers (Innovia Films)1; epoxy polymers from bio-glycerol; and starch polymers and blends (AkzoNobel [National Starch Chemical] and several other players). NatureWorks (Cargill Dow) is the major commercial player with a PLA capacity of 280 million lbs2; and Novamont is the major producer of starch polymers and blends, with a capacity of 120 million lbs.3
The total capacity of biopolymers is expected to reach 1.3 billion lbs, if Braskem's 400 million lbs/year of bio-polyethylene production and Braskem's/Nova Zymes's 400 million lbs/year4 of
While the current R&D efforts look promising due to advances in bacterial and plant sciences, the reality is that the development of biopolymer products is in its infancy stage due to challenges involved in developing a truly biodegradable product. Finding the right bacterial system and then developing a process for commercial readiness is not a simple, but a daunting task.
Plant-based biopolymers are based on green sources and typically cost more in energy and processing than conventional polymers. Government subsidies, tax credits, and other incentives provided to farmers and end-users further obscures the real cost of production.
Although PLA was known as the first commercially available synthetic "biodegradable" polymer, it is now recognized as a "compostable" polymer (heat and moisture are needed to degrade it).5 In addition, infrared sensor devices are required to sort out PLA from other wastes. The portion of biopolymer waste in landfills is infinitesimal. Having waste management try to find biopolymer waste from a colossal pile of garbage is like finding a needle in a haystack. The current amount of plastics, glass, and paper that is recycled is small and most of these used products end up in landfills. One can expect the same trend for biopolymer wastes, and given that they would not undergo total biodegradation without heat and moisture, these products would also contribute to creating more landfills. Until a truly biodegradable product is developed, governments will need to improve public awareness and increase efforts for recycling/appropriate waste management from its current state. Germany has taken a lead towards this effort.
Also PLA and other biopolymers compete with bio-ethyl acetate and other bio fuels such as bio-ethanol and bio-diesel, which are also made from the same natural sources of corn, sugarcane, etc. These sources are the backbone of our food industry. Even if biopolymer production currently contributes only minimally towards food scarcity and its increase in costs, the potential to eventually further limit lands for food production will continue to raise public debate.
There are also other factors. Cultivation of land for biopolymers makes the land unavailable for other food crops, forcing the need for deforestation. Another issue is that bio-products, like food products, are at the mercy of Mother Nature. Just as floods, droughts, and unpredictable seasonal variations can impact the supply of crops for food, these environmental factors could impact the stability of biopolymer production as well. Finally, the environmental costs to convert marginal land into a fertile farm for production of corn or sugarcane is excessive, and involves the use of large amounts of agricultural machines (tractors, harvesters, tillage equipment, grinders, choppers, etc.) which are based on diesel, fuel, and gas. In addition, expensive chemical fertilizers are used to increase the harvest yield and frequency of harvests each year.The use of diesel, fuel, and gas will create more greenhouse gases; and the use of chemical fertilizers will reduce the organic matter of soil, further contributing to greenhouse gas emissions.5
The inter-twining dichotomy of bio- and food products competing for the same resources, coupled with politically driven green initiatives has distorted the intrinsic potential value of biopolymers. Although these arguments are valid, they fail to highlight the potential niche for the biopolymer market.
Monday, April 12, 2010
Tuesday, April 6, 2010
Gosau is Environmental and Energy Programs Manager for research company, Adherent Technologies Inc (ATI) based in Albuquerque, New Mexico, USA. The company has worked on recycling processes since 1995, with $3 million (€2 million) in funding along the way from the US Departments of Defense and Energy and an alliance with Titan Technologies. Titan is an Albuquerque developer of a pyrolysis process for recycling automobile tyres.
“In the mid-1990s,” Gosau indicates, “we ran the gauntlet with pyrolysis, trying to hit just the right temperature/oxygen content sweet spot, and decided it was not optimal for CFRP recycling as our primary process.”
ATI has evolved a catalytic conversion technology centred around its batch-based carbon fibre recyclate processing, combining three different processes studied over the past decade, each with specific advantages and limitations.
Vacuum pyrolysis, a dry process operated at around 500°C (932°F), recovers resins as marketable liquids and can be easily scaled up to multi-tonne capacity. At this temperature, however, fibre product may retain oxidation residue or char.
The company’s low-temperature liquid process operates at 150°C (302°F), runs at less than 150 psi on standard equipment, and produces a market-ready fibre, but is not particularly tolerant of scrap contaminants (such as metal, wire, paint and sealants). The high temperature liquid option (around 300°C/572°F) produces clean fibres from most composites, but requires customised equipment and is currently not considered necessary for commercial recyclate production. Phenol has proven a good choice as initial heat transfer fluid for both wet processes; the breakdown products of the resin can be recycled into glue for the production of plywood.
ATI has demonstrated its low-temperature wet process in combination with vacuum pyrolysis for the removal of insoluble contaminants in a pilot-scale reactor capable of processing 23 kg (50 lbs) an hour.
Gosau adds that testing of its recycling technology on CFRP scrap with multiple resin chemistries indicates that the combination of dry and wet processes is the best way to maximise recyclate quality. Low temperature wet chemical processing removes the bulk of the resin and some contaminants, followed by thermal post-treatment through vacuum pyrolysis to eliminate remaining resin and produce 99% fibre purity.
“This may not result in the most elegant processing,” Gosau concludes, “but we can handle the true mixed soup of CFRP waste without the need for time-consuming and expensive hand sorting, making it financially viable. Further, the combined approach eliminates the need for any solvent use.”
ATI’s recycling technology used this combined approach to recycle scrap from test articles built within the Boeing 787 Dreamliner programme. The thick laminate structure, which utilises a thermoplastic toughener in an interlayer between the carbon fibre/epoxy layers, presented near intractability in terms of recyclability. Application of ATI’s low temperature wet process completely dissolved the epoxy but left the toughener behind. Next, vacuum pyrolysis at 525°C (977°F) removed the toughener and other contaminants.
For any company involved in the development of the CFRP recycling industry, there is a performance perception problem to be dealt with. This is the idea that recycled carbon fibres are of secondary or “lesser than” quality than virgin carbon fibre (VCF). While recyclate properties vary, leading R&D indicates that properties reduction of only 3-5% compared to VCF has been exhibited in reclaimed chopped and milled fibres used to make thermoplastic compounds such as bulk moulding compound (BMC).
Even when recyclate with performance properties comparable to VCF, evolving the business of CFRP recycling involves formidable requirements. Gosau lists those as “consistent scrap availability, appropriate size reduction technologies for the CFRP waste, established process parameters, the infrastructure for secondary operations such as material collection at a manufacturer’s site, and eventually, creation of standardised recyclate product properties.”Currently, ATI’s recycling technology solutions await licensees or possible turnkey operations partners, though Gosau verifies them as “robust and definitely commercially viable for proceeding to next-level production at 1000 tonnes/annum.” Further, at the suggested price of US$5/lb for recyclate, the company believes a reasonable profit can be made.