218
8
The pultrusion process is a continuous operation that can
be readily automated. It is adaptable to both simple and
complex cross-sectional shapes. Very high strengths are
possible due to the fibre loading. The manufacturing cost in
this process is low. The glass rovings, cloth, or mat come out
from a wound spool and go through the resin bath through nip
rollers, as shown in . Fig. 8.10. Then the impregnated glass
rovings, cloth, or mat go through the die and adapt to the
shape of the profile of the die. At this point, curing also takes
place so that the pultruded composite’s profile gets cured and
the permanent shape, profile, and cross section are formed.
5 Processability Parameters—The following are the processability
parameters for processing polymeric composites using the
pultrusion process.
5 Type of matrix resin—Room-temperature as well as
high- temperature curing thermosetting resins are processable using the pultrusion process. Thermoplastic matrices
are not processable by pultrusion technology.
5 Form of reinforcement—Only continuous reinforcements
(such as fabric, tapes, rovings, tows, and CSM) can be
processed in pultrusion technology. Short fibres, whiskers,
and particles are not processable by this processing
technology.
5 Mould design—The mould design needs to support the
continuous production; therefore, the composite is processable only when the profile of the cross section is regular, the
sliding surface of the mould is smooth, and an adequate
heating arrangement for the curing of the product is
available.
5 Residence time in the mould—The residence time of the
green composite in the mould is an important processing
parameter. It must be optimum for curing. If the time of
residence is less than the required time, the composite
would not be cured, and if the residence time is more than
required time, the thermal degradation and/or excessive
cross-link density may cause a brittle composite.
Glass
roving
Tension
roller
Resin
bath
Outlet
Heated
die
Pulling
roller
Cured
profile
. Fig. 8.10 Schematic of pultrusion process [15]
Chapter 8 · Processability in Closed Mould Processing of Polymeric Composites
8
The pultrusion process is a continuous operation that can
be readily automated. It is adaptable to both simple and
complex cross-sectional shapes. Very high strengths are
possible due to the fibre loading. The manufacturing cost in
this process is low. The glass rovings, cloth, or mat come out
from a wound spool and go through the resin bath through nip
rollers, as shown in . Fig. 8.10. Then the impregnated glass
rovings, cloth, or mat go through the die and adapt to the
shape of the profile of the die. At this point, curing also takes
place so that the pultruded composite’s profile gets cured and
the permanent shape, profile, and cross section are formed.
5 Processability Parameters—The following are the processability
parameters for processing polymeric composites using the
pultrusion process.
5 Type of matrix resin—Room-temperature as well as
high- temperature curing thermosetting resins are processable using the pultrusion process. Thermoplastic matrices
are not processable by pultrusion technology.
5 Form of reinforcement—Only continuous reinforcements
(such as fabric, tapes, rovings, tows, and CSM) can be
processed in pultrusion technology. Short fibres, whiskers,
and particles are not processable by this processing
technology.
5 Mould design—The mould design needs to support the
continuous production; therefore, the composite is processable only when the profile of the cross section is regular, the
sliding surface of the mould is smooth, and an adequate
heating arrangement for the curing of the product is
available.
5 Residence time in the mould—The residence time of the
green composite in the mould is an important processing
parameter. It must be optimum for curing. If the time of
residence is less than the required time, the composite
would not be cured, and if the residence time is more than
required time, the thermal degradation and/or excessive
cross-link density may cause a brittle composite.
Glass
roving
Tension
roller
Resin
bath
Outlet
Heated
die
Pulling
roller
Cured
profile
. Fig. 8.10 Schematic of pultrusion process [15]
Chapter 8 · Processability in Closed Mould Processing of Polymeric Composites