121
5
explained in Pludeman’s theory. Note that –R groups make covalent
bonds with matrix resin.
Titanate coupling agents are limited to inorganic reinforcements,
and they form an organic monolayer over the surface of inorganic
reinforcement, such as glass fibres. The usage of titanate coupling
agents causes a reduction in the viscosity of the matrix after interaction with it. Titanate coupling agents cause good adhesion between
fibres and the matrix, improve the dispersion of short fibres or fillers
in the matrix due to reduction of the viscosity of the resin matrix,
improve the impact strength of the composite, and do not cause
embrittlement of the composite. Titanate coupling agents may be
classified as monoalkoxy (isopropyl triisostearoyltitanate, isopropyl
triacriloyltitanate, etc.), chelate (dimethacryloyl, oxoethylene titanate, di(dioctyl)pyrophosphate, oxoethylenetitanate), and neoalkoxy
(neopentyl(diallyl)oxytrineodecanonyltitanate) coordinate and quat
types [7].
? Example 5.1 Explain the process of the application of a
silane coupling agent on the surface of glass fabric in the
industry.
v Answer
The steps involved in treating the surface of glass fibres with
silane coupling agent are given here.
5 Step 1. A sizing agent such as starch, gum, or polyvinyl
alcohol (PVA) is applied on the surface of freshly drawn glass
fibres. This helps in the handling of glass fibres without
breakages.
5 Step 2. The sized glass fibres are converted into tarns, and they
are woven into the fabric of the desired weave.
5 Step 3. The sizing agent is washed with water to expose the
nascent surface of the glass fibres.
5 Step 4. The glass fabric is immediately passed through a bath
containing an aqueous solution of a silane coupling agent. The
speed of drawing glass fabric is kept constant in order to allow
the silane to adhere reactively on the surface of the glass
fibres.
5 Step 5.The fabric is dried using a hot air blower and packaged
for transportation.
5.1.2 Carbon Fibre
Carbon fibre contains pure carbon, and its fabric is shown in
. Fig. 5.3. The salient features of carbon fibres are the following:
5 Carbon fibre is highly inert.
5 The surface layer of nascent carbon fibre is weak due to skin–
core heterogeneity.
5 There is a difference in morphology between high-modulus
(HM) and high-strength (HS) carbon fibres.
5.1 · Interface and Interphase in Thermosetting Composites
5
explained in Pludeman’s theory. Note that –R groups make covalent
bonds with matrix resin.
Titanate coupling agents are limited to inorganic reinforcements,
and they form an organic monolayer over the surface of inorganic
reinforcement, such as glass fibres. The usage of titanate coupling
agents causes a reduction in the viscosity of the matrix after interaction with it. Titanate coupling agents cause good adhesion between
fibres and the matrix, improve the dispersion of short fibres or fillers
in the matrix due to reduction of the viscosity of the resin matrix,
improve the impact strength of the composite, and do not cause
embrittlement of the composite. Titanate coupling agents may be
classified as monoalkoxy (isopropyl triisostearoyltitanate, isopropyl
triacriloyltitanate, etc.), chelate (dimethacryloyl, oxoethylene titanate, di(dioctyl)pyrophosphate, oxoethylenetitanate), and neoalkoxy
(neopentyl(diallyl)oxytrineodecanonyltitanate) coordinate and quat
types [7].
? Example 5.1 Explain the process of the application of a
silane coupling agent on the surface of glass fabric in the
industry.
v Answer
The steps involved in treating the surface of glass fibres with
silane coupling agent are given here.
5 Step 1. A sizing agent such as starch, gum, or polyvinyl
alcohol (PVA) is applied on the surface of freshly drawn glass
fibres. This helps in the handling of glass fibres without
breakages.
5 Step 2. The sized glass fibres are converted into tarns, and they
are woven into the fabric of the desired weave.
5 Step 3. The sizing agent is washed with water to expose the
nascent surface of the glass fibres.
5 Step 4. The glass fabric is immediately passed through a bath
containing an aqueous solution of a silane coupling agent. The
speed of drawing glass fabric is kept constant in order to allow
the silane to adhere reactively on the surface of the glass
fibres.
5 Step 5.The fabric is dried using a hot air blower and packaged
for transportation.
5.1.2 Carbon Fibre
Carbon fibre contains pure carbon, and its fabric is shown in
. Fig. 5.3. The salient features of carbon fibres are the following:
5 Carbon fibre is highly inert.
5 The surface layer of nascent carbon fibre is weak due to skin–
core heterogeneity.
5 There is a difference in morphology between high-modulus
(HM) and high-strength (HS) carbon fibres.
5.1 · Interface and Interphase in Thermosetting Composites