Besides automakers' lightweighting efforts, they're also interested in reducing sound and vibration, both inside and outside the vehicle. A renewable version of Dow Automotive Systems' polyurethane cavity sealing Betafoam system, which achieves both, is now on the market.
Dow's new product, Betafoam Renue, is made with 25 percent renewable materials based on soybean oil, Allan James, performance systems marketing manager for Dow Automotive Systems, told us. It's a two-part polyurethane rigid foam system that offers the same performance as the existing Betafoam system, which is made with low-emissions MDI (methylene diphenyl disocyanate), an ingredient used in polyurethane manufacturing. Renue is 25 percent less dense, however, at a nominal density of 1.45 gm/cc versus BETAFOAM's 2.0 gm/cc.
A renewable version of Dow Automotive Systems' polyurethane cavity sealing BETAFOAM system can help cars lose weight and cut noise. (Source: Dow Automotive Systems)
The existing Betafoam 89100 and 89120 products are helping 30 cars now in production lose weight. These include the BMW X3, Dodge Charger, Audi R8, Cadillac CTS, Buick Enclave, and Lamborghini Gallardo. "We've been in this market for about 15 years or so," said James. "With Betafoam Renue, we hope to replace the 89100 and 89120 products first in those models, and then move to others that don't use Betafoam now." The new material has been in trials since October 2011.
Typically, Betafoam is used to seal vehicle cavities, such as A, B, and C pillars and rocker panels to reduce air and road noise and vibration, as well as resonance buildup within the cavity-filler location. It improves acoustical performance by between 1dB and 5dB. Betafoam can completely fill complex, three-dimensional crevices because it is pumped into the cavity, leading to much lower leakage.
The new Renue product can also be processed within the same process window, a critical issue for automakers. "Our customers who are replacing with the Renue product want to know that we can process it within the same temperature versus rate window," said James. "We not only match the window of current production, but with Renue there's a broader window of processing temperature by rate: we can run lower rates and temperatures."
Earlier this year, in a talk he gave at the Applied Market Information Bioplastics Compounding and Processing 2012 Conference, James detailed the performance and processing advantages of Betafoam over traditional baffles. The results of a repeatability side-by-side analysis on 25 production vehicles showed fewer leaks and lighter weight with the cavity sealing foam system, and a potential mass savings of up to 30 percent, depending on cavity size. Lower material viscosity and faster reactivity produced additional manufacturing efficiencies.
Renue was developed partly with a grant from the United Soybean Board. Since it's derived from oils, not soy protein, it does not affect food crop production, said James. "This is an industrial product, more of a byproduct of food production."
Love to see these efforts around creating renewable versions of proven materials and carrying over many of the same characteristics so they have high utility for materials engineers. Makes it very easy to go the sustainability route when the choices are just part of good, everyday design practices.
@Ann: Are you sure that the density is 1.45 g/cm³? This is equivalent to 90 pounds per cubic foot. At this density, the foam would sink in water. The density of a typical polyurethane sound-absorbing foam is around 2 pounds per cubic foot (about 0.03 g/cm³). Are you sure the density wasn't given in U.S. units, rather than metric units?
Generally, the sound absorption of foams depends on the frequency of the sound. Any indication of what frequency range this foam is best suited for?
Also, any word on whether Dow has any plans to market this material in sheet form? Or will it be sold only as an injectable cavity foam?
Finally, how does the cost of the soy-based polyurethane compare to petroleum-based polyurethanes? This will definitely be a big factor in its acceptance.
I also think it's cool that this cavity foam using a non-food renewable material that's a byproduct of food production. Many materials companies are getting on the bandwagon to ensure that their feedstocks are really green: both renewable and non-competitive with the human food supply.
@Ann: Calling soybean oil a "byproduct of food production" rather than a food product is a little disingenuous. Soybean oil is one of the most widely-consumed cooking oils.
It's true that the soy flakes, which remain after the oil is extracted, are used as animal feed (and for soy protein for human consumption). Using the oil as an industrial feedstock wouldn't affect this use.
Of course, soybean oil is already widely used in industry -- for instance, it's used to make ink -- and it seems unlikely that the (relatively) small amount of additional soybean oil which would be used to make these foams would have any impact on the price or supply of cooking oil.
Dave, the spec Dow provided was 1.45 gm/cc. Note that that's 25 percent less dense than the previous product at 2.0 gm/cc. James did not provide price details, or mention sheet forms of this product or any other future plans regarding it.
Dave, at least one of the specs were on their presentations and they were also given in the interview. I find it tough to believe that anyone at Dow would mistake units of measurement. I've sent an email asking them to verify the spec.
at that density, and considering that as a foam it consists of mainly air, the material of the foam itself would have to be denser than lead! must be a typo.
edit- from the dow chemicals betafoam brochure (not the new one):
BETAFOAM classic and low-MDI acoustic foam products range in density from 2 pcf to 5 pcf.
We've just heard back from Allan James, the person I interviewed at Dow. The spec he gave me was, in fact, wrong--thanks to Dave Palmer for pointing that out. James says the correct measurements are 1.45 pcf for BETAFOAM Renue and 2.0 pcf for the product being replaced.
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