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below are several video clips from a brief interview with
Joannie Chin, one of the NIST materials research engineers
responsible for designing experiments for the SPHERE (Simulated
Photodegradation by High Energy Radiant Exposure). The SPHERE
was developed by NIST in conjunction with industry and government
partners to accurately and quickly determine the damage to
polymer coatings, materials and structures exposed to the
sun's ultraviolet rays, temperature, and humidity. The facility
will help speed the introduction of new products into the
market and reduce building repair costs.
Question:
I understand that the NIST SPHERE is considered to be one
of the world's most sophisticated testing devices for measuring
weathering from ultraviolet exposure. Besides the large, sphere
structure, what else does the instrument include?
Click
to view video clip 1.
Chin:
We also have a set of very intense UV lamps that the sphere
is also equipped with which provides us with the equivalent
of about 22 suns worth of ultraviolet radiation. And the purpose
of the sphere is to provide accelerated UV weathering to polymer
specimens that would otherwise be exposed in an outdoor environment.
Outdoor exposures are very expensive to carry out. They are
carried out in real-time so they take a very long period of
evaluation. What we have is the ability to do these exposures
very quickly under very precisely controlled conditions of
ultraviolet radiation, temperature, and humidity.
Question:
What type of outdoor facilities do manufacturers use now to
test their products?
Click
to view video clip 2.
Chin:
There are many sites across the country and throughout the
world that companies that produce polymeric materials will
use. These exposures are generally carried out for between
five to ten to sometimes 15 years. The other thing which is
done is accelerated testing in laboratories using commercially
available UV weathering instrumentation. What we provide is
the ability to more precisely control the exposure that the
materials get. And we also have the ability to provide a great
deal more UV intensity than the normal capabilities of commercial
equipment.
Question:
What types of materials do you test in the SPHERE?
Click
to view video clip 3.
Chin:
This type of research is carried out on anything that is made
of a plastic or polymeric material. These types of materials
are highly susceptible to ultraviolet degradation. And that's
why the finish on your brand new car looks good for a couple
of years and then fades. That's why the paint on your house
starts flaking and chipping after a few years. It's all due
to the effects of ultraviolet radiation. So anything that's
based on a polymer or contains a polymer or a plastic material
is usually tested before its introduction into the marketplace
for its UV resistance.
Question:
Where do you see use of this technology heading in the next
5 to 10 years?
Click
to view video clip 4.
Chin:
What we'd like to see is that the industry actually changes
some of their testing methodologies to include the use of
devices such as the one we're building. This device actually
goes along with a methodology that we're trying to propose
to the industry, involving the measurement of UV dosage rather
than the measurement of time of exposure. That's a parameter
that we feel is a much more quantitative and easily understood
measure rather than the use of the time parameter.
Related NIST Links
NIST
News Announcement about the SPHERE
Service
Life Prediction of Polymeric Materials (detailed project
description)
Materials
and Construction Research Division
Building
and Fire Research Laboratory
 Go
back to NIST News Page
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