| Abstract | A study has been performed to investigate resin cure and associated characteristics
of composite used in CIPP technique (cured-in-place pipe). CIPP have been employed to
rehabilitate deteriorated pipe line. Such liners are often subjected to external hydrostatic
pressure which may eventually lead to creep or buckling of the liner within the host pipe.
The main objectives of the research are:
O To increase flexural modulus without adversely effecting the strength.
O To improve the curing and thermo mechanical properties of resin-felt
system.
Numerous tests were performed on curing systems using DMA (Dynamic
Mechanical Analyzer) technique to evaluate material cure and progression for various
cataKst percentages. Gellation, vitrification, working open time and glass transition (Tg)
were all assessed.
A Time Temperature Transformation (TTT) profiles were proposed for three
different systems of 2. 3 and 4% w/w catalyst (Figures 8.3. 8.4 and 8.6). indicating the
various phases of cure progression (liquid / rubber / glassy and degradation) and further
developed using DMA technique in penetration mode. The unique TTT profiles of
unsaturated polyester resin in adjacent with nonwoven polyester felt developed to create
the similar environment of CIPP production outside of the laboratory condition.
In an attempt to enhance the physical and mechanical properties of the liner
materials, many different additives were considered. However, it was found that silicon
carbide (SiC) nanoparticles can potentially increase the flexural modulus and hardness of
the liner materials. However due to the high cost of SiC. various amounts of crystalline
SiC>2 (silica) and amorphous SiOo (rice husk ash, RHA) were used to achieve the most
optimum mechanical properties.
To improve the interfacial interaction between matrix and reinforcement, a suitable
coupling agent was used. In the process, Differential Scanning Calorimetric (DSC) was
used to evaluate the exothermic behaviour of the samples, scanning electron microscopy
(SEM) was used to appraise the mechanism of failure. Thermogravimetry anahsis
(TGA) was applied to measure the amount of volatility in the materials. The mechanical performance of all the samples was evaluated using flexural.
microhardness, tensile, ring stiffness and creep-recovery tests. Additionally creeprecovery
test yielded useful results on the shrinkage of different composite samples
containing silica, SiC and RHA.
It emerged that by using 8-10% w/w Silica treated by coupling agent resulted in
the most cost effective solution, yielding a 30% improvement in flexural modulus of the
liner material, this was found to be due to a stronger matrix-reinforcement interfacial
interaction.
Furthermore, thermo-mechanical properties of different polymer pipe materials
used in pipe renovation, including MDPE. HOPE, U-PVC. M-PVC and PUR, were
evaluated using DMA.
The results of this study indicated that a developed CIPP liner made from polyester
felt impregnated with unsaturated polyester resin, containing 10% SiC>2 additive
(coupling agent treated) yielded the optimum mechanical performance, with a storage
modulus of 1876 MPa, which is noticeably higher than that of different modern pipe
materials on the market (PUR. MDPE, HOPE. PVC-U, PVC-M). This improvement in
the results has been attributed to the development of optimum interfacial bond strength
between silica, matrix and felt. Also this optimum formulation showed excellent
toughness performance. The investigation into the thermo-mechanical properties of the
optimised CIPP (UPE/F10%SP+CA samples), shows that the developed CIPP has been
achieved the best performance in pipeline application. |
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