Long-term moisture absorption and durability of FRP pultruded rebars

Abstract Up to 15-years long moisture diffusion into carbon, glass, and aramid fiber reinforced plastic (FRP) rebars is studied. To eliminate uncertainties in identification of the radial and axial diffusivities, a successive methodology for determination of the diffusion coefficients is proposed. The concept of apparent diffusivity taking into account anisotropy and edge effects is extended to cylindrical samples. The ratio of the axial and radial diffusivities is the lowest for carbon (3) and the highest for glass (81) FRP rebars. Durability performance of the rebars is estimated by monitoring their interlaminar shear strength (ILSS). Long-term exposure of FRP rebars in a humid environmen…

Anomalous water diffusion in epoxy/carbon nanoparticle composites

Abstract Water absorption-desorption-resorption and swelling were studied for a DGEBA-based amine-cured epoxy resin filled with four types of carbon nanoparticles: multiwall carbon nanotubes (MWCNT), graphite nano-platelets (GnP), expanded graphite platelets, and carbon black. Nanocomposites are characterised by lower diffusivity (down to 20% for epoxy/GnP) and increased water sorption capacity compared to the neat epoxy. Anomalous water absorption and swelling of nanocomposites is finely described by the diffusion-relaxation model. The relaxation times, considered as quantitative indicators of changes in segmental mobility of the polymer, increased with addition of nanoparticles and decrea…

Cyclic moisture sorption and its effects on the thermomechanical properties of epoxy and epoxy/MWCNT nanocomposite

The aim of this work was to reveal the moisture absorption&ndash

Relationship between the residual and total strain from creep‐recovery tests of polypropylene/multiwall carbon nanotube composites

Environmental Effects on Mechanical, Thermophysical and Electrical Properties of Epoxy Resin Filled with Carbon Nanofillers

The aim of this work was to establish the effect of environmental factors (moisture and temperature) on some mechanical, electrical and thermal properties of epoxy-based composites filled with carbon nanofillers: nanotubes (CNT), nanofibers (CNF) and hybrid nanofiller (nanotubes/nanofibers in the ratio 1:1) and to reveal the most environmentally stable NC. First, the nanocomposites (NC) containing different nanofiller contents were prepared to evaluate electrical percolation threshold and to choose NC at certain electrical conductivity for further characterization of the physical properties in initial state and during/after environmental ageing. The environmental ageing consisted of water a…

Prediction method of electrical conductivity of nano-modified glass fibre reinforced plastics

Glass fibre reinforced plastics (GFRP) is non-conductive construction material, however with carbon nanotubes (CNT) modifying it can get additional functionality due to its gained electrical conductivity. Main aim of the study is to check functionality of the prediction method of electrical conductivity of GFRP with nano-modified epoxy matrix using structural approach. GFRP composites under investigation were based on unidirectional (UD) Glass fiber and two matrixes modified with carbon nanotubes. Electrical conductivity of epoxy resin modified by CNT (concentrations < 1%) was modelled using structural approach. Electrical conductivity of unidirectional GFRP layer was measured experimentall…

Effect of Core–Shell Rubber Nanoparticles on the Mechanical Properties of Epoxy and Epoxy-Based CFRP

This research was funded by M-Era.Net project MERF “Matrix for carbon reinforced epoxy laminates with reduced flammability” grant No. 1.1.1.5/ERANET/20/04 from the Latvian State Education Development Agency and M-Era.Net project “EPIC—European Partnership for Improved Composites“ funded by grant No. TH06020001. A.S., K.S. and A.Z. are grateful to funding received from the European Union Horizon 2020 Framework program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.