Patrice Cousin

Temperature as an Accelerating Factor for Long-Term Durability Testing of FRPs: Should There Be Any Limitations?

Fiber-reinforced polymer (FRP) composites are increasingly being used in civil engineering applications due to their numerous advantages. Moreover, some environmental conditions can potentially enhance their long-term durability. Therefore, the study of their long-term behavior is crucial to ensure their durability. To perform durability study in a reasonable time limit, accelerating factor, such as high temperature, is generally used. However, the use of very high temperature of conditioning could amplify the reduction of the properties leading to conservative prediction of long-term properties. The present paper attempts to clarify the effects of high temperatures on the mechanical and barrier properties (moisture absorption) of GFRP’s internal reinforcement, by presenting some experimental results and conclusions of laboratory accelerated studies.

Durability Assessment of Glass FRP Solid and Hollow Bars (Rock Bolts) for Application in Ground Control of Jurong Rock Caverns in Singapore

AbstractThis study was conducted to investigate the durability of two types of vinyl-ester/glass fiber-reinforced polymer (GFRP) rock bolts [solid and hollow (tubular) GFRP bars] that were subseque...

In Situ Synthesis and Characterization of Silver/Polymer Nanocomposites by Thermal Cationic Polymerization Processes at Room Temperature: Initiating Systems Based on Organosilanes and Starch Nanocrystals

New methods for the preparation of silver nanoparticles/polymer nanocomposite materials by thermal cationic polymerization of ε-caprolactone (ε-CL) or α-pinene oxide (α-PO) at room temperature (RT) and under air were developed. The new initiating systems were based on silanes (Si), starch nanocrystals (StN) and metal salts. Excellent polymerization profiles were revealed. It was shown that silver nanoparticles (Ag(0) NPs) were in situ formed and that the addition of StN improves the polymerization efficiency. The as-synthesized nanocomposite materials contained spherical nanoparticles homogeneously dispersed in the polymer matrices. Polymers and nanoparticles were characterized by gel permeation chromatography (GPC), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. A coherent picture of the involved chemical mechanisms is presented.

Improvement of the interphase between basalt fibers and vinylester by nano-reinforced post-sizing

Basalt fiber reinforced composites are innovative materials which may be used as an alternative to glass fiber-based composites in civil engineering applications. They exhibit high temperature resistance, corrosion resistance, low cost and excellent mechanical properties. However, according to previous studies, weak interfaces between the basalt fiber and the thermoset resin, such as polyvinylester, could be a problem for the use of basalt fibers reinforced polymers (BFRP) for civil engineering applications. To solve this problem, this study investigates the improvement of properties of basalt fibers coated with silica nano-reinforced epoxy resin. Three types of coatings were tested: epoxy resin, epoxy resin treated with fumed silica, and epoxy resin treated with silane-treated fumed silica. Silica nanoparticles were characterized by Fourier Transform Infrared Spectrometry (FTIR), Thermal Gravimetric Analysis (TGA) and micro-electrophoresis (Zeta-Nanosizer). Basalt fibers were dip-coated in diluted solutions/suspensions of epoxy coatings in acetone and analyzed using Scanning Electron Microscopy (SEM). Basalt fibers/vinylester (VE) composites were then prepared by compression molding. Tensile tests and interlaminar shear tests (ILSS) were performed on the different molded BFRP. Preliminary results show a 5–25 % improvement in mechanical properties depending on the type of coating. The presence of nanosilica at the interface between the basalt fiber and VE matrix leads to a significant enhancement of interlaminar and ultimate tensile strength.

Effect of modified graphene oxide on the mechanical, thermal, and barrier properties of vinylester

Graphene, which is a one atom thick layer of graphite, has been considerably studied in the past decade due to its extraordinary physical properties. The development of new routes of synthesis facilitates the use of graphene in polymer nanocomposite. The addition of very small amounts (<1%) of graphene in a polymer matrix does not only increase its thermal and mechanical properties, but it would also enhance permeability, by limiting the diffusion of water through the material. Graphene-polymer nanocomposite would be an interesting alternative to conventional polymer nanocomposite such as nanoclay-polymer nanocomposite. In this study, graphene oxide is synthesized from graphite flakes, following the Tour method, and modified with silane to improve its compatibility with the polymer. Polymer nanocomposite made from vinylester resin and 0.5 wt% graphene oxide is prepared as well as other types of typically used polymer nanocomposite such as graphite flake, silica fume or nanoclay based composite. Samples are soaked in a water bath to study the water absorption of these nanocomposites. Mechanical property measurements and thermal analyses are performed to evaluate the benefit of using graphene oxide. Results show a significant enhancement of the mechanical and thermal properties with a graphene oxide content ten times lower than the one needed with conventional nanoparticles. Moreover, unlike nanoclay-based polymer nanocomposite, graphene oxide does not increase water absorption at saturation.