Findings (MAT SC)
Findings (MAT SC)
Findings (MAT SC)
Furthermore, thermosets are the most popular of the fiber composite matrices
without which, research and development in structural engineering field could get
truncated. Aerospace components, automobile parts, defense systems etc., use a
great deal of this type of fiber composites. Epoxy matrix materials are used in printed
circuit boards and similar areas.
Epoxy resins are widely used in filament-wound composites and are suitable
for moulding prepress. They are reasonably stable to chemical attacks and are
excellent adherents having slow shrinkage during curing and no emission of volatile
gases. These advantages, however, make the use of epoxies rather expensive.
Polyester resins on the other hand are quite easily accessible, cheap and find
use in a wide range of fields. Liquid polyesters are stored at room temperature for
months, sometimes for years and the mere addition of a catalyst can cure the matrix
material within a short time. They are used in automobile and structural applications.
The cured polyester is usually rigid or flexible as the case may be and
transparent. Polyesters withstand the variations of environment and stable against
chemicals. Other advantages of polyesters include easy compatibility with few glass
fibers and can be used with verify of reinforced plastic accoutrey.
Thermoplastics have one- or two-dimensional molecular structure and they
tend to at an elevated temperature and show exaggerated melting point. Another
advantage is that the process of softening at elevated temperatures can reversed to
regain its properties during cooling, facilitating applications of conventional compress
techniques to mould the compounds.
The advantage of thermoplastics systems over thermosets are that there are
no chemical reactions involved, which often result in the release of gases or heat.
Manufacturing is limited by the time required for heating, shaping and cooling the
structures.
Most metals and alloys make good matrices. However, practically, the
choices for low temperature applications are not many. Only light metals are
responsive, with their low density proving an advantage. Titanium, Aluminium and
magnesium are the popular matrix metals currently in vogue, which are particularly
useful for aircraft applications. If metallic matrix materials have to offer high strength,
they require high modulus reinforcements. The strength-to-weight ratios of resulting
composites can be higher than most alloys.
Ceramics can be described as solid materials which exhibit very strong ionic
bonding in general and in few cases covalent bonding. High melting points, good
corrosion resistance, stability at elevated temperatures and high compressive
strength, render ceramic-based matrix materials a favourite for applications requiring
a structural material that doesn’t give way at temperatures above 1500ºC. Naturally,
ceramic matrices are the obvious choice for high temperature applications.
High modulus of elasticity and low tensile strain, which most ceramics
posses, have combined to cause the failure of attempts to add reinforcements to
obtain strength improvement. This is because at the stress levels at which ceramics
rupture, there is insufficient elongation of the matrix which keeps composite from
transferring an effective quantum of load to the reinforcement and the composite may
fail unless the percentage of fiber volume is high enough. A material is reinforcement
to utilize the higher tensile strength of the fiber, to produce an increase in load
bearing capacity of the matrix. Addition of high-strength fiber to a weaker ceramic
has not always been successful and often the resultant composite has proved to be
weaker.
References
3MB Co., Ltd. 2017. Polymer Matrix Composites and their applications. Retrieved May 16
https://nptel.ac.in/courses/Webcourse-contents/IISc-BANG/Composite
%20Materials/pdf/Lecture_Notes/LNm1.pdf