135
5
3. Vinyl Ester Resins—Vinyl ester resins are made through a
condensation reaction of DGEBA with acrylic or methacrylic
acid. Methacrylic acid-based vinyl ester resins are used in the
composite industry, whereas acrylic acid-based vinyl ester
resins are used for coating purposes. Epoxy resin is commonly
used for manufacturing of composite structures; therefore, the
properties of vinyl ester resins may be tailored for the use of
different grades of epoxy resins. Water from a reaction comes
out as a condensate. Vinyl ester resins have properties of both
epoxy and polyester resins. Vinyl ester resins have both good
mechanical strength (like epoxy resin) and good UV resistance
(like UPE resin). The curing agents, curing reactions, and
mechanisms are similar to those of UPE resins. The general
properties of vinyl ester resins have been mentioned in
7 Chap. 1. The major processability factors for vinyl ester resins
are given here.
5 The viscosities of vinyl ester resins are low.
5 Vinyl ester resins have low shrinkage (> 0.5%).
4. Phenol Formaldehyde Resin—Phenol formaldehyde resin is
commonly known as phenolic resin. It is made from a condensation reaction of phenol and formaldehyde. This goes through
a further condensation reaction during curing and releases
water from the reaction as a condensate. Phenol formaldehyde
resin is used as a matrix for high-temperature applications,
ablative liners (due to good charring capabilities), and the
fabrication of carbon–carbon composites (CCC) (again due to
good carbonaceous content and charring capabilities). The
general properties of phenolic resins have been mentioned in
7 Chap. 1. The major processability factors for phenolic resins
are as follows:
5 The viscosities of phenolic resins are low.
5 Phenol formaldehyde resin cures at high temperature (such
as 150–160 °C) and does not require any curing agent or
hardener.
5 During curing, water of the reaction needs to be removed
from the composite part.
5 Phenolic resins have problems advancing in the reaction;
therefore, the formation of tiny cross-linked lumps of resin
causes difficulty with its processability.
5 The resin must be stored under cool and dry conditions.
The advancement of reaction leading some cross-linking
may be identified by the presence of water (water of
reaction) on the upper surface of the resin.
5 Phenolic resins have low shrinkage (<0.5%).
5. Bismaleimide Resins—Bismaleimide (BMI) resins are hightemperature resins and are abundantly used in the composite
industry. They are used in applications where good thermal
performance coupled with good mechanical properties is
needed. Their mechanical performance is inferior to epoxy and
isophthalic UPE resins. BMI resins are prepared from a
condensation reaction of maleic anhydride and aromatic
diamine (such as DDM). Water from the reaction comes out as
5.3 · Thermosetting Composites
5
3. Vinyl Ester Resins—Vinyl ester resins are made through a
condensation reaction of DGEBA with acrylic or methacrylic
acid. Methacrylic acid-based vinyl ester resins are used in the
composite industry, whereas acrylic acid-based vinyl ester
resins are used for coating purposes. Epoxy resin is commonly
used for manufacturing of composite structures; therefore, the
properties of vinyl ester resins may be tailored for the use of
different grades of epoxy resins. Water from a reaction comes
out as a condensate. Vinyl ester resins have properties of both
epoxy and polyester resins. Vinyl ester resins have both good
mechanical strength (like epoxy resin) and good UV resistance
(like UPE resin). The curing agents, curing reactions, and
mechanisms are similar to those of UPE resins. The general
properties of vinyl ester resins have been mentioned in
7 Chap. 1. The major processability factors for vinyl ester resins
are given here.
5 The viscosities of vinyl ester resins are low.
5 Vinyl ester resins have low shrinkage (> 0.5%).
4. Phenol Formaldehyde Resin—Phenol formaldehyde resin is
commonly known as phenolic resin. It is made from a condensation reaction of phenol and formaldehyde. This goes through
a further condensation reaction during curing and releases
water from the reaction as a condensate. Phenol formaldehyde
resin is used as a matrix for high-temperature applications,
ablative liners (due to good charring capabilities), and the
fabrication of carbon–carbon composites (CCC) (again due to
good carbonaceous content and charring capabilities). The
general properties of phenolic resins have been mentioned in
7 Chap. 1. The major processability factors for phenolic resins
are as follows:
5 The viscosities of phenolic resins are low.
5 Phenol formaldehyde resin cures at high temperature (such
as 150–160 °C) and does not require any curing agent or
hardener.
5 During curing, water of the reaction needs to be removed
from the composite part.
5 Phenolic resins have problems advancing in the reaction;
therefore, the formation of tiny cross-linked lumps of resin
causes difficulty with its processability.
5 The resin must be stored under cool and dry conditions.
The advancement of reaction leading some cross-linking
may be identified by the presence of water (water of
reaction) on the upper surface of the resin.
5 Phenolic resins have low shrinkage (<0.5%).
5. Bismaleimide Resins—Bismaleimide (BMI) resins are hightemperature resins and are abundantly used in the composite
industry. They are used in applications where good thermal
performance coupled with good mechanical properties is
needed. Their mechanical performance is inferior to epoxy and
isophthalic UPE resins. BMI resins are prepared from a
condensation reaction of maleic anhydride and aromatic
diamine (such as DDM). Water from the reaction comes out as
5.3 · Thermosetting Composites