Effect of Polymer Waste Mix Filler on Polymer Concrete Composites.

The hazards of polymer waste and emitted gas on the environment pose a global challenge. As a trial to control this, the current work aims to reuse the polymer waste mix (PM) as fillers in calcium silicate to prepare new composites of environmentally friendly polymer concrete. PM was first subjected to treatment to obtain treated PM (TPM) and then was filled in new dicalcium silicate cement with different concentrations. The microstructural characterizations declare the successful preparation of the dicalcium silicate base material. After the curing reaction, the precipitated carbonate main product is responsible for the gained properties. The CO2 uptake% in the proposed composites reached 16.6%, referring to the successful storage of CO2 gas during curing. The treatment reaction led to an increase in the flexural and compression strengths due to the strengthening of the polymer waste mix-cement interface; the strengths were increased gradually with more contents of TPM fillers. 7% TPM-cement concentration achieved the highest flexural strength and compression strength of10.2 and 12.7%, respectively, compared with blank cement. The used polymer improved slightly the pull-off force of the prepared cement, and 7 and 5% TPM-cement composites have the maximum values. All the proposed composites passed the impact testing without failure, where the combination between the polymer waste and silicate cement resulted in a stable composite surface. Compared with the blank, the different concentrations of TPM-cement composites show more stability against water absorption. In addition, the proposed composites and blank cement have a very low carbon dioxide emission. The ability to recycle the polymer waste, form new type of low-energy silicate, improve the mechanical and surface properties, uptake CO2 gas, and reduce gas emission makes the proposed polymer waste mix-cement composites as environmentally friendly construction products.

Environmentally Friendly Polymer Concrete: Polymer Treatment, Processing, and Investigating Carbon Footprint with Climate Change.

Climate change is being currently faced globally; controlling the plastic waste and gas emission is aimed to reduce their hazardous effects. In this work, polyethylene terephthalate (PET) and polyvinyl chloride (PVC) polymer wastes are used as fillers to calcium silicate. Chemical treatment was performed to get the best efficiency of the binder material with the treated PET (TPET) and treated PVC (TPVC). The used silicate, new nonhydraulic dicalcium silicate, was synthesized by sintering. A new environmentally friendly polymer concrete, based on different concentrations of PET-/TPET-/PVC-/TPVC-dicalcium silicate composites, was prepared and cured by carbonation. FTIR analysis confirms that the treatment gave functional groups on the polymer surface; also, the hydrophilicity was increased after treatment. SEM photos show that the treated polymers have a rougher surface, which led to improved attachment with cement. The structures of the prepared and cured cement materials are proved by XRD, FTIR analysis, and SEM, through the change of calcium silicate to carbonate. Carbon footprint is used to analyze the environmental implications of the prepared composites. After the treatment reaction, the TPET-cement and TPVC-cement composites showed improved compression and flexural properties and more stability against water absorption. The novelty arises from recycling this plastic waste in the proposed low-energy dicalcium silicate cement, for the first time, to give improved environmentally friendly composites after converting CO2 gas to carbonates, with the reduced carbon footprint.

Monitoring Moisture Damage Propagation in GFRP Composites Using Carbon Nanoparticles.

Glass fiber reinforced polymer (GFRP) composites are widely used in infrastructure applications including water structures due to their relatively high durability, high strength to weight ratio, and non-corrosiveness. Here we demonstrate the potential use of carbon nanoparticles dispersed during GFRP composite fabrication to reduce water absorption of GFRP and to enable monitoring of moisture damage propagation in GFRP composites. GFRP coupons incorporating 2.0 wt % carbon nanofibers (CNFs) and 2.0 wt % multi-wall carbon nanotubes (MWCNTs) were fabricated in order to study the effect of moisture damage on mechanical properties of GFRP. Water absorption tests were carried out by immersing the GFRP coupons in a seawater bath at two temperatures for a time period of three months. Effects of water immersion on the mechanical properties and glass transition temperature of GFRP were investigated. Furthermore, moisture damage in GFRP was monitored by measuring the electrical conductivity of the GFRP coupons. It was shown that carbon nanoparticles can provide a means of self-sensing that enables the monitoring of moisture damage in GFRP. Despite the success of the proposed technique, it might not be able to efficiently describe moisture damage propagation in GFRP beyond a specific threshold because of the relatively high electrical conductivity of seawater. Microstructural investigations using Fourier Transform Infrared (FTIR) explained the significance of seawater immersion time and temperature on the different levels of moisture damage in GFRP.

Monitoring Damage Propagation in Glass Fiber Composites Using Carbon Nanofibers.

In this work, we report the potential use of novel carbon nanofibers (CNFs), dispersed during fabrication of glass fiber composites to monitor damage propagation under static loading. The use of CNFs enables a transformation of the typically non-conductive glass fiber composites into new fiber composites with appreciable electrical conductivity. The percolation limit of CNFs/epoxy nanocomposites was first quantified. The electromechanical responses of glass fiber composites fabricated using CNFs/epoxy nanocomposite were examined under static tension loads. The experimental observations showed a nonlinear change of electrical conductivity of glass fiber composites incorporating CNFs versus the stress level under static load. Microstructural investigations proved the ability of CNFs to alter the polymer matrix and to produce a new polymer nanocomposite with a connected nanofiber network with improved electrical properties and different mechanical properties compared with the neat epoxy. It is concluded that incorporating CNFs during fabrication of glass fiber composites can provide an innovative means of self-sensing that will allow damage propagation to be monitored in glass fiber composites.

Improved Strength and Toughness of Carbon Woven Fabric Composites with Functionalized MWCNTs.

This investigation examines the role of carboxyl functionalized multi-walled carbon nanotubes (COOH-MWCNTs) in the on- and off-axis flexure and the shear responses of thin carbon woven fabric composite plates. The chemically functionalized COOH-MWCNTs were used to fabricate epoxy nanocomposites and, subsequently, carbon woven fabric plates to be tested on flexure and shear. In addition to the neat epoxy, three loadings of COOH-MWCNTs were examined: 0.5 wt%, 1.0 wt% and 1.5 wt% of epoxy. While no significant statistical difference in the flexure response of the on-axis specimens was observed, significant increases in the flexure strength, modulus and toughness of the off-axis specimens were observed. The average increase in flexure strength and flexure modulus with the addition of 1.5 wt% COOH-MWCNTs improved by 28% and 19%, respectively. Finite element modeling is used to demonstrate fiber domination in on-axis flexure behavior and matrix domination in off-axis flexure behavior. Furthermore, the 1.5 wt% COOH-MWCNTs increased the toughness of carbon woven composites tested on shear by 33%. Microstructural investigation using Fourier Transform Infrared Spectroscopy (FTIR) proves the existence of chemical bonds between the COOH-MWCNTs and the epoxy matrix.