Influence of cenosphere on CAI strength of glass epoxy laminate

Under controlled lab settings, two distinct laminates, one containing cenosphere and the other with neat resin, were evaluated for impact using a Fractovis impact machine, compression testing, and compression after impact tests (CAI) with a Tinus Olsen UTM. The GFRP laminates were made by hand lay-up method with 16 layers of glass fiber in 4.7±0.2 mm thickness and combined with epoxy resin reinforced Cenospheres at concentrations of 1, 3 and 5 wt. %, according to ASTM specifications. The dominant failure mode controlling the specimen's compression ultimate load resistance, and other failure modes of impacted specimens such like fiber pull-out and debonding, were found to be the effects of delamination using coupled acoustic emission (AE) monitoring and compression tests. On specimens with a 3 wt. % filler additive, there was a noticeable increase in strength. Both impacted and non-impacted samples exhibited significant compression ultimate load resistances, with the 3 wt. % filler impregnated specimen having the maximum.

Utilization of tyre rubber hybrid with ceramic and wood for impact energy absorption application

The used tyre rubber, scrap ceramic tiles and wood dust are largely dumped into landfills, which create environmental pollution to the surrounding. The recycling of tyre rubber is very limited, but it has good property to absorb the impact energy. Hence, these materials are used to prepare the composite in the present work. Composite materials were prepared by the resin transfer moulding method with different weight percentage of particles. The tensile, flexural and impact strength of composite specimens were compared with other combination of composites and also with the neat resin sample specimen. The tensile and flexural strength of composites were decreased with the addition of the rubber. But, the rubber particle with the ceramic in the resin matrix increases the impact strength of composite by 45.91% when compared with the neat resin sample. The addition of rubber enhances the impact strength of composite materials with all the combination of particles. The better distribution and good interfacial adhesion of particles with a resin matrix along the fractured surface were observed by the scanning electron microscope. And also, the nature of failure was identified by morphological studies.

Utilization of CFRP waste as a filler in polyester resin-based composites

The paper presents an attempt to use milled waste of carbon fiber reinforced polymer (rCFRP) laminates as fillers for polyester resin. The obtained polyester-rCFRP composites were tested for technological, mechanical and frictional properties. It was found that the viscosity increased for the compositions containing rCFRP particles in comparison to the neat resin. Flexural strength improved in comparison to the neat resin, but only for the composites filled with a fraction containing particles below 0.2 mm in diameter and a mixed-diameter particles fraction. For composites containing the above-mentioned fractions, a significant reduction in the dynamic friction coefficient and a reduction in wear (the weight loss after friction test) were found. The obtained results indicate the advisability of further research and optimization of this new type of composites in terms of frictional applications.

Durability of Concrete Superficially Treated with Nano-Silica and Silane/Nano-Clay Coatings

Protection of the surface layer of concrete is essential for achieving durability and functionality of concrete elements during their service life. In this paper, an effort is made to utilize colloidal nano-silica (5%–50%) and a synthesized nanocomposite as superficial treatments for concrete; silane was used as the neat resin to disperse nano-montmorillonite particles at different dosages (5% and 10%). The coatings were applied to a typical concrete mixture used for residential concrete in North America. The transport properties of the treated concrete were characterized using the rapid chloride penetrability test and the absorption/desorption percentages. Moreover, concrete was evaluated under severe durability exposure involving physical salt attack (PSA), which is a wetting/drying regime responsible for surface damage of concrete elements subjected to continuous salt supply along with cyclic ambient conditions. Deterioration was visually assessed and quantified using mass change. In addition, thermal and microscopy analyses were performed on concrete specimens to elucidate the mechanisms of enhancement by surface treatment. The results showed that increasing the concentration of nano-silica particles in the colloid led to an improved performance of concrete, with the 50% loading ratio achieving the least penetration depth, absorption/desorption percentage, and mass loss of concrete under aggravated PSA. For the silane/nano-clay composite, the low dosage of nano-clay was adequate to mitigate the damage caused by PSA on concrete.

Enhancement of Thermal and Mechanical Properties of Bismaleimide Using a Graphene Oxide Modified by Epoxy Silane

A thermosetting resin system, based on bismaleimide (BMI), has been developed via copolymerization of 4,4′-diaminodiphenylsulfone with a newly synthesized graphene oxide modified using epoxy silane (ES-GO). The effect of ES-GO on the thermomechanical and mechanical properties of cured modified resin was studied. To evaluate the efficiency of the modified BMI systems, the composite samples using glass fiber cloth were molded and tested. Thermogravimetric analysis indicates that the cured sample systems displays a high char yield at lower concentrations of ES-GO (≤0.5 wt.%), suggesting an improved thermal stability. Using dynamic mechanical analysis, a marked increase in glass transition temperature (Tg) with increasing ES-GO content was observed. Analysis of mechanical properties reveals a possible effect of ES-GO as a toughener. The results also showed that the addition of 0.3 wt.% ES-GO maximizes the toughness of the modified resin systems, which was further confirmed by the result of analysis of fracture surfaces. At the same time, a molded composite with ES-GO showed improved mechanical properties and retention rate at 150 °C as compared to that made with neat resin.

An Innovative Green Process for the Stabilization and Valorization of Organic Fraction of Municipal Solid Waste (OFMSW): Optimization of the Curing Process II Part

This work is focused on the optimization of an innovative and cheap process for the valorization of the organic fraction of municipal solid waste (OFMSW), through its transformation into an odorless and environmentally compatible material to be employed for building applications or as a thermal and acoustic insulator. The process starts with the grinding of OFMSW, followed by its sterilization in order to obtain a complete removal of the bacterial activity. Afterwards, the incorporation in a catalysed thermosetting matrix is carried out by mixing the OFMSW to a water soluble urea formaldehyde based resin (UF), characterized by a formaldehyde content lower than 1% wt. The OFMSW/UF blends were firstly analysed by the dynamic rheological analyses, as a function of the content of a proper catalyst, that is able to decrease the curing temperature and time. Rheological analyses results allowed the selection of times and temperatures necessary for the polymerization (T = 60 °C, t = 1 h). The effect of the presence of different additives on both the cure process and the mechanical properties of the cured samples was finally analysed, evidencing that the OFMSW/UF composites possess improved mechanical properties in comparison to that of the neat resin.

Influence of Commercial Biochar Fillers on Brittleness/Ductility of Epoxy Resin Composites

Production of versatile composites is a very attractive field. Carbon containing epoxy resins are one of the most relevant reinforced plastics used for a wide number of applications. In this research, we studied the influence of five different commercial biochar samples for the selective enhancement of brittleness and ductility of an epoxy based composite. We proved the relationship between biochar morphology and composites mechanical properties with the aid of FT-IR and FE-SEM analysis. We were able to improve the neat resin mechanical properties by doubling its Young’s modulus and ultimate tensile strength using a wheat straw derived material, and to increase its elongation by 40%, we used a Miscanthus derived biochar.

Fabrication of Graphene-Reinforced Nanocomposites with Improved Fracture Toughness in Net Shape for Complex 3D Structures via Digital Light Processing

A solvent-free method to fabricate graphene-reinforced nanocomposites in net shape via digital light processing (DLP) 3D printing has been developed in this work. The effect of graphene nanofillers on resin viscosity and wettability for various printing parameters has been examined, with a systematic characterization of the mechanical and thermomechanical properties. With the addition of 0.5 wt.% graphene nanoplatelets in the resin, the flexural modulus and fracture toughness have been improved by 14% and 28% from neat resin, respectively. Thermomechanical properties of graphene-reinforced nanocomposites were also enhanced compared with the neat resin, without scarification in their printability. The feasibility of utilizing the DLP method to fabricate a fracture toughness specimen (KIC test) without complex skill-dependent notch preparation steps was explored, with different notch tip angles printed for net-shaped specimens. This provided a simple and versatile way to perform a quick examination of reinforcing efficiency from nanofillers at very low cost with high resolution and reproducibility. To demonstrate the suitability of current resins for complexly shaped structures, a gyroid scaffold for tissue engineering applications based on current graphene nanocomposite resins has been successfully fabricated via DLP, showing the great potential of current photocurable resins for applications in various fields such as tissue engineering or personalized medical devices without the cost barriers of traditional methods.