ARCHIVED - Lighter, Stronger, "Greener" Plastics

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February 05, 2005— Ottawa, Ontario

In the 1967 film "The Graduate" a young and aimless Dustin Hoffman receives a memorable piece of advice to get a job in the plastics industry. This advice was perceptive considering that, in the U.S., plastics is the fourth largest manufacturing industry in terms of shipments.

Open cell foam of a bio-polymer prepared with processing via CO2 at room conditions. (This project is a result of collaboration between NRC-ICPET researchers Dr. Victoria Nawaby, Dr. Abdiaziz Farah, Dr. Xia Liao, Dr. Mike Day and York University professor of Chemistry, Dr. William Pietro.)
Open cell foam of a bio-polymer prepared with processing via CO2 at room conditions. (This project is a result of collaboration between NRC-ICPET researchers Dr. Victoria Nawaby, Dr. Abdiaziz Farah, Dr. Xia Liao, Dr. Mike Day and York University professor of Chemistry, Dr. William Pietro.)

As large as the plastics industry is, there is always room for improvement. The majority of plastics on the market are derived from petrochemical sources, a finite and non-renewable resource. This basic fact has created efforts to conserve this resource, by finding new sources to make plastics from, and improving manufacturing methods. Improved manufacturing processes and materials are expected to result in more energy-efficient, sustainable processes that produce lighter, stronger and more durable products. Particularly in the automotive sector, lighter, stronger plastic parts can produce noticeable energy savings, while reducing Green House Gas (GHG) emissions.

Building a Better Foam

Lighter, stronger plastics – produced by more sustainable manufacturing processes – are brought together with NRC research into specialized plastics or polymer foams.

 
 
Biopolymers
 
 

NRC researchers are also investigating the properties of plastics made from renewable plant-based sources, such as corn. A team from NRC-ICPET, in partnership with the University of Ottawa and a Japanese firm, recently submitted their findings to the upcoming Annual Technical Meeting of Society of Plastic Engineers (ANTEC) on efforts to create unique biopolymer foams from a corn-based polymer known as polylactic acid

 
 

According to the Freedonia Group, U.S. demand for foamed plastics will reach 7.8 billion pounds in 2005. But, materials used to create these foams, such as HCFCs [hydrochlorofluorocarbons], contribute ozone depletion. Under international agreements their use will eventually be phased out. As a result, industry is seriously examining the use of more environmentally-friendly methods to produce foams, including the use of CO2.

According to Dr. Victoria Nawaby of the NRC Institute for Chemical Process and Environmental Technology (NRC-ICPET), it is not just a simple case of switching from one gas to another. Even small changes in pressure and temperature can affect the solubility of CO2 which can affect the properties of the foam. It is here that NRC research can play a major role. "There are a number of variables that, from a processing perspective, are very important to know. Unless you know this information, you simply won't be able to create the material that you're looking for," says Nawaby.

NRC-ICPET researchers have reported on the interaction of a polymer blend with CO2 which, depending on the concentration of the blend and saturation pressure, as well as temperature of the gas, creates different foam structures or morphologies As a result NRC-ICPET's polymer research team (Drs. Mike Day and Victoria Nawaby) have focused heavily on experimentation and testing aimed at fully understanding the interaction between CO2 and a series of commercially available polymers for potential biomedical, automotive and electronic applications.

Combining new materials and sustainable processes

Closed cell foams prepared at NRC-ICPET from a thermoplastic material via CO2 processing at sub-critical conditions.
Closed cell foams prepared at NRC-ICPET from a thermoplastic material via CO2 processing at sub-critical conditions.

Work doesn't stop with producing the perfect foam. Nawaby points out that while considerable research is taking place into investigating foaming techniques with CO2 at supercritical conditions (extremes in temperature and pressure), the team is also producing good results working at so-called sub-critical conditions. In everyday terms, this would equal the kinds of normal conditions that would be found on the shop floor, and gets back to the overarching concern about reducing energy and creating sustainable processes. "Most of the research focus is still at the supercritical state, but there are questions of energy efficiency," Nawaby notes. "We want to shift our focus towards foaming techniques and materials that can be quickly adopted by industry and are not as energy intensive to produce".

Foam

What makes a perfect foam? For automotive applications small, closed and uniformly-spaced cells produce extremely strong polymer foams. For biomedical applications, however, a more open cell and interconnected foam structure is preferable. This will allow for nutrients and other biological materials to pass freely between the cavities. NRC-ICPET research is investigating foams suitable to both applications.

Finally, NRC-ICPET's research team expects added dividends through work being carried out jointly with researchers at the NRC Institute for Industrial Materials (NRC-IMI).

For several years, the NRC-IMI team has been perfecting techniques involving the use of clay nanoparticles to create new nanocomposite plastics. Nanocomposites have been proven to dramatically increase the strength of polymer materials. Just last year, NRC-IMI launched a joint industry partnership group focused on nanocomposites to further explore the use of such materials. It is hoped that nanoclays will add critical strength to already lightweight foamed materials. As well, nanoparticles have been shown to enhance the growth of foam cells, a process known as nucleation. In the past year, a NRC-ICPET research team, in collaboration with University of Ottawa, became the second group in the world to publish results on the fundamental interaction of CO2 with nanocomposites - an emerging area of study.

All of this is proof that advice given by the film industry in 1967 still holds true – plastics continues to be a major growth industry with a sustainable future.



Enquiries: Media relations
National Research Council of Canada
613-991-1431
media@nrc-cnrc.gc.ca

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