The field of advanced composite materials remains dominated by fiber reinforced polymers with upper

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bris.ac.uk/ias
Lecture Announcement Tuesday, July 14, 2009,
1200 Queens Building, Room 1.18
Resin Transfer Molded Composites for Application
at High Temperatures
Donald W. Radford, IAS Benjamin Meaker Visiting
Professor Dr. Radford is on sabbatical leave from
Colorado State University, where he is an
Associate Professor of Mechanical Engineering and
the Director of the Composite Materials,
Manufacture and Structures Laboratory
The field of advanced composite materials remains
dominated by fiber reinforced polymers with upper
use temperatures below 200C. Even in these
well-accepted composites, a significant fraction
of the research and development efforts currently
focus on increased quality of manufactured
product and on processing technologies which
enable higher volume/lower cost production.
Historically, efforts to extend this temperature
range have been based on intermetallic and
ceramic matrix materials, and the target use
temperature range has generally been above
1100C. Unfortunately, the resulting materials
have seen limited application and the cost of
processing has remained high. However, many
engineering applications could benefit from
advances in composite materials which can
function, structurally, in a temperature range
lying between 200C and 1100C. More
importantly, generating a composite which is
readily manufactured with good structural
performance in these intermediate temperatures
could have very significant implications. Recent
research has been undertaken to investigate
processing of high temperature capable composites
using resin transfer molding (RTM). The matrix
materials under consideration are a series of
high temperature polyimides (LaRC PETI-RTM,
PETI-8 and RP-46) for application temperatures
approaching 400C, and an inorganic polymer
(Cordi MEYEB geopolymer) for application
temperatures up to 800C. Both types of
materials have been successfully resin transfer
molded with fiber contents exceeding 50 Vf
however, continued research is necessary to
address issues related to component quality and
performance. The demonstration components for
both materials are internal combustion engine
poppet valves polyimide matrix intake valves and
inorganic polymer matrix exhaust valves. Intake
valves based on PETI-RTM have been run in
fired-engine testing, where temperatures exceed
350C, for up to 400 minutes. MEYEB matrix
composites have been heat treated for various
lengths of time to temperatures as high as 900C,
followed by mechanical testing at room
temperature. Results of these studies will be
described. Further, current technical issues
related to void control in the polyimide matrix
composites will be discussed as will residual
stress development during processing. The
inorganic matrix composite processing research
has also addressed residual stress generation
during processing however, much of the activity
revolves around improvements in toughness of the
composite. Each of these matrix material
candidates incrementally advance the use
temperature capability of fiber reinforced
composites over more conventional polymer matrix
materials, but unlike many previous high
temperature capable composites, they enable net
shape, potentially high volume, production
techniques to be applied.