The development of nanoscale reinforcements, which can tailor the interfacial strength and impart multiple functionalities on carbon fiber reinforced polymer (CFRP) composites, remains a challenge for their largescale adoption in diverse applications ranging from aerospace to transportation and construction industries. In this work radially aligned graphene nanoflakes (GNFs), grown directly on carbon fibers (CFs) via a simple one-step microwave plasma enhanced chemical vapor deposition method, without any catalyst, were used as a novel nano-reinforcement interface. A remarkable 28% enhancement in the tensile strength of the hybrid fibers was observed via singlefiber tensile strength tests, whereas the interfacial shear strength (IFSS) increased by 101.5%. Our results demonstrate that GNFs not only improve the interfacial strength between the GNFs and the epoxy resin but also enhance the in-plane mechanical strength of the CFsa well-known problem encountered with the direct growth of carbon nanotubes on CFs. In addition, GNFs provided embedded functionality via increased electrical conductivity (60.5% improvement for yarns and 16% for single fiber) and electrochemical capacitance (157% for yarns). This work indicates the potential of GNFs as an interphase for the simplified and costeffective production of stronger multifunctional CFRP composite materials.
This study presents, the development of a green method to produce rich in thymol natural zeolite (TO@NZ) nanostructures. This material was used to prepare sodium-alginate/glycerol/xTO@NZ (ALG/G/TO@NZ) nanocomposite active films for the packaging of soft cheese to extend its shelf-life. Differential scanning calorimetry (DSC), X-ray analysis (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) instruments were used for the characterization of such nanostructures and films, to identify the thymol adsorbed amount, to investigate the thermal behaviour, and to confirm the dispersion of nanostructure powder into the polymer matrix. Water vapor transmission rate, oxygen permeation analyzer, tensile measurements, antioxidant measurements, and antimicrobial measurements were used to estimate the film’s water and oxygen barrier, mechanical properties, nanostructure’s nanoreinforcement activity, antioxidant and antimicrobial activity. The findings from the study revealed that ALG/G/TO@NZ nanocomposite film could be used as an active packaging film for foods with enhanced, mechanical properties, oxygen and water barrier, antioxidant and antimicrobial activity, and it is capable of extending food shelf-life.
The global turn from the linear to the circular economy imposes changes in common activities such as food packaging. The use of biodegradable materials such as polyvinyl alcohol, natural raw materials such as clays, and food byproducts such as chitosan to develop novel food packaging films attracts the interest of industrial and institutional research centers. In this study, novel hybrid nanostructures were synthesized via the growth of zinc oxide nanorods on the surface of two nanoclays. The obtained nanostructures were incorporated with chitosan/polyvinyl alcohol composite either as nanoreinforcement or as an active agent to develop packaging films. The developed films were characterized via XRD, FTIR, mechanical, water-vapor diffusion, water sorption, and oxygen permeability measurements. Antimicrobial activity measurements were carried out against four different pathogen microorganisms. XRD indicated the formation of an intercalated nanocomposite structure for both types of nanoclays. Furthermore, improved tensile, water/oxygen barrier, and antimicrobial properties were recorded for all films compared to the pure chitosan/polyvinyl alcohol film. Overall, the results indicated that the use of the bio-based developed films led to an extension of food shelf life and could be used as novel active food packaging materials. Among them, the most promising film was the 6% wt. ZnO@halloysite.
A long-standing challenge in structural material design is the simultaneous attainment of high strength and toughness, a conflicting requirement rarely met in engineering materials, with important technological applications in aerospace, defense, automobile, and marine industries. Motivated from examples in biological materials, to address this challenge, we demonstrate that strong and damagetolerant carbon-fiber-reinforced polymers (CFRPs) can be realized via the direct growth of self-assembled radially aligned graphene nanoflakes (GNFs) on carbon fibers (CFs). Here, we report a first-of-its-kind study on the dependence of strength and toughness on the surface morphology of GNFs in CFRPs. The results indicated that fracture toughness was dependent on the density and waviness of the GNFs, whereas the tensile strength was also affected by the periodicity of the coated carbon fiber layers into the laminated structures. Notably, GNFs with reduced waviness and increased number of layers exhibited enhancement in interlaminar fracture toughness for modes I and II by 93.8% and 43.3%, respectively, whereas GNFs with increased waviness led to a marginal increase or preserved tensile strength. The highly interconnected and wavy nature of GNFs facilitated effective load transfer in both in-plane and out-of-plane directions. Moreover, the out-of-plane through-volume conductivity was remarkably enhanced by 527%. The results of this work demonstrated for the first time the unique potential of GNFs, as an excellent nanoreinforcement and electrically conducting interface, for achieving simultaneously strong, tough, and conducting multifunctional CFRP composites.
Modern day energy codes are driving the design and multi-layered configuration of exterior wall systems with a significant emphasis on achieving high performance insulation towards improving energy performance of building envelopes. Use of highly insulating polyisocyanurate (PIR) based materials enhanced with eco-friendly lamellar inorganic fillers reinforces energy performance requirements, environmental challenges and cost reduction without compromising the overall building fire safety. The current work assessed the fire behaviour of PIR modified with three layered fillers, namely MgAlCO3 (PIR-LDH1), MgAl Stearate (PIR-LDH2) and Zirconium Phosphate octadecylamine (PIR-ZrP3). For each of the fillers, three loadings (2, 4 and 6 % by weight) were used.Optical analysis by X-ray diffraction patterns (XRD), cone calorimeter (CC), thermogravimetric (TGA) analysis, post-burning morphological evaluation using field emission scanning electron microscope (FESEM) and diffuse reflectance infrared spectroscopy (DRIFT) analysis, were performed. The results indicated that fire reaction properties and thermal stability of foam samples were enhanced with three different types of lamellar inorganic smart fillers. The initial degradation temperature of PIR-layered filler samples was increased, demonstrating that incorporation of flame retardants decelerated the degradation of PIR foam and contributed to significant char formation, from 19.5% in pure PIR samples to 33% in PIR-6%LDH1 samples. Increasing the filler content also resulted in improved char properties and decreased peak Heat Release Rates (HRR) in the cone calorimeter.Due to the development of a stable char layer, samples containing 6% of ZrP3 did not ignite at 20kW/m 2 and a reduction of up to 40% in the peak HRR was achieved in PIR-2%ZrP3 samples.
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