A review of recent developments in flammability of polymer nanocomposites

Polymer nanocomposite flame retardancy has become a critical parameter in industrial material application. Recent environmental policies have prohibited the incorporation of halogenated flame-retardant compounds into polymers owing to the high level of environmental degradation caused by high levels of toxic gas and smoke emission. The demand for zero-halogen flame-retardant compounds by both researchers and manufacturers is due to the inherent advantages accruable from their incorporation like very minimal toxic emission, minimal smoke release, zero corrosive gas release, reduced corrosion activities and absence of dripping in fire condition. This has necessitated the quest for eco-compliant replacements for halogenated flame suppressants. Recent insight has shown the eco-compliancy of exfoliated graphene nanoplatelets as flame retardants when incorporated into polymer nanocomposites (PNCs). Relative to the propensity to retard flame, increasing quantities of exfoliated graphene nanoplatelets have exhibited the capability to significantly repress critical flammability parameters like heat release rate (HRR), peak HRR (PHRR), rate of carbon monoxide production, smoke production rate and total mass loss rate while simultaneously increasing limiting oxygen index, time of ignition and total PHRR, thereby retarding flammability and creating better chance to reduce loss and casualty in real-life fire situation through the formation of even layers of carbonaceous char in the condensed phase capable of efficiently suppressing the thermal decomposition caused by oxygen and heat to the polymer matrix and cutting off the flaming path. This paper gives an insight into recent developments in flame retardancy of PNCs, with special emphasis on the flame-retardancy propensity of exfoliated graphite nanoplatelets

Construction, characterization, properties and multifunctional applications of stimuli-responsive shape memory polymeric nanoarchitectures:a review

Due to the advent of nanotechnology, deficiencies and limitations inherent in stimuli-responsive shape memory polymeric matrices (SMP), have been effectively mitigated, through the inclusion of a versatile range of organic or inorganic nanoparticulates within the confines of SMP matrice/s. This phenomenon has resulted in the emergence of shape-memory polymeric nanoarchitectures (SMPNs) possessing enhanced and outstanding properties, when compared with the pristine SMP, and this has subsequently enlarged their scope of applications (civil engineering, biomedical gadgets, aerospace, bionics engineering, energy, electronic engineering, household products, and textile engineering). Furthermore, SMPNs enhances athermal stimuli-activities including electroactivity, magneto-activity, water-activity, and photo-activity, as well as shape memory effect (SME) including multiple-shape memory effect (MSME), spatial shape memory effect (SSME), as well as dual-route shape memory effect (DRSME). This elucidation is essential and imperative at this time to enlighten the polymeric universe on new advancements in fabrication, features and applications of stimuli responsive SMPNs. Therefore, this paper, presents, very recently emerging advancements, in construction, characterization, properties and multifunctional applications of stimuli-responsive SMPNs with special emphasis on carbon nanotubes (CNT), carbon nanofibers (CNF), cellulose nanocrystals, and nanoclay reinforced SMPNs.</p

Emerging advancements in xerogel polymeric bionanoarchitectures and applications

Xerogels (X-G) are biopolymeric and zero chemical materials, applied in regenerative medicine and tissue engineering because of inherently elevated biocompatibility, nil-immunogenicity, as well as zero-cytotoxicity. X-G are porous, functional and advanced materials composed of dried, cross-linked and ambient polymeric structures possessing very elevated porosity, broad surface area, as we as inexpensive fabrication pathway capable of being garnered from varying organic and inorganic initiators for multifunctional applications. Due to their inherently desirous properties, X-G are appropriate for numerous medical as well as biomedical uses. Relative to their elevated drug delivery capacity, X-G ability of maintaining sustainable drug releasing present them highly suitable for drug conveying applications. Biopolymeric materials exhibit capability of interacting, cross-linking, and/or trapping severally inclined active entities, like antibiotics or naturally occurring antimicrobial substrates, which are critically essential for wound dressing as well as other mending applications. Hence, X-G are capable of being utilized in antibodies trapping, enzymes, as well as cells for biosensor and monitoring gadgets. Therefore, this paper presents recently emerging trends in X-G polymeric bionanoarchitectures encompassing biopolymeric X-G introduction, strategies of construction, as well as their properties. Herein, biological attributes sustaining their suitability for versatile biomedical uses especially biosensing, tissue scaffolding, drug conveying, wound mending and dressing are comprehensively elucidated

Effect of exfoliated graphite nanoplatelets on thermal and heat deflection properties of kenaf polypropylene hybrid nanocomposites

Exfoliated graphite nanoplatelet (GNP) polypropylene (PP)/kenaf fiber (KF) hybrid nanocomposites (PP/KF/MAPP/GNP collectively presented as PKMG) were developed through melt extrusion using a co-rotating screw speed extruder. The loadings of GNPs in nanocomposites were varied from 1-5 phr and characterized for thermal conductivity, stability and behavior, morphology, and heat deflection temperature (HDT). Results revealed increasing effective thermal conductivity with increasing inclusion of GNP. This behavior was attributed to the formation of thermally conductive, interconnected, sheets of GNP which enhanced heat dissipation. Thermal stability analysis revealed high thermal residue content at 3 phr loading attributed to uniform dispersion of GNP sheets in polymer matrix and the formation of enhanced oxygen-barrier due to effective char formation. Results also revealed enhanced HDT (0.46 MPa/1.8 MPa) with increasing incorporation of GNP ascribed to high modulus and thermal stability of GNP sheets. This implies capability of material to sustain loading at high temperatures without losing its rigidity. Thermal behavior revealed increased crystallization temperature and reduced degree of crystallization with slight increase in melting temperature in the range of 2-5°C. Morphological analysis using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) revealed exfoliated and uniform dispersion of graphene in matrix polymer at 3 phr loading

Emerging trends in graphene carbon based polymer nanocomposites and applications

Recent sustainable advancement in carbon nanotechnology has further broadened the scope of application of carbon based materials, especially graphene based polymer nanocomposites, in emerging applications. This paper mainly focuses on recently emerging trends in synthesis and properties of graphene based polymer nanocomposites, in addition to brief discussion of some selected carbon based nanocomposites for application in electromagnetic interference shielding efficiency, terahertz shielding efficiency, electrostatic dissipation, thermal interface materials, sensors, and energy storage. Finally, an overview of recently emerging trends in sustainability, economies of scale, and emerging commercial market share of these materials is also presented

Emerging trends in flame retardancy of biofibers, biopolymers, biocomposites, and bionanocomposites

Recent advancements in natural fiber-reinforced polymer composites have engineered the need to procure alternatives to replace metals in automotives, construction, aerospace, defense, electronics, and gas and oil industries. However, application versatility of biomaterials has been limited due to poor flame retardancy. In line with the new CO2 emission policy and global ban on halogenated flame retardants, the automotive and aerospace industries require environmentally benign materials with nonhalogenated flame retardancy, that can provide the high FPI, and low FGI, required to reduce fatalities and destruction of properties during real fire situations. Researchers, therefore, postulate that versatility of application of biomaterials can be attained by improving their fire retardant properties. Hence, this paper reviews novel emerging technologies used in achieving flame retardancy in biofibers, biopolymers, biocomposites, and bionanocomposites

Emerging trends in eco-compliant, synergistic, and hybrid assembling of multifunctional polymeric bionanocomposites

The quest to develop eco-benign polymeric hybrid materials arose out of the need to protect the environment from the harmful effects of synthetic petroleum polymeric waste and meet the specific needs of industries such as oil and gas, aerospace, automotives, packaging, electronics biomedicals, pharmaceuticals, agricultural, and construction. This has resulted in synergistic hybrid assembling of natural fibers, polymers, biopolymers, and nanoparticles. Bionanocomposites based on inorganic nanoparticle reinforced biofiber, polymers and biopolymers, and polysaccharides such as chitosan, alginate, and cellulose derivatives, and so on, exhibiting at least a dimension at the nanometer scale, are an emerging group of nanostructured hybrid materials. These hybrid bionanocomposites exhibit structural and multifunctional properties suitable for versatile applications similar to polymer nanocomposites. Their biocompatibility and biodegradability provide opportunities for applications as eco-benign green nanocomposites. This review presents state-of-the-art progress in synergistic nanotechnological assembling of bionanocomposites relative to processing technologies, product development, and applications

Characterization and preparation of conductive exfoliated graphene nanoplatelets kenaf fibre hybrid polypropylene composites

Exfoliated graphene nanoplatelets (GNP) kenaf fiber (KF) hybrid polypropylene (PP) composites materials were prepared by melt extrusion followed by injection molding. PP/KF/MAPP/GNP composites 0-5 phr were prepared and characterized using X-ray diffraction (XRD), differential scanning calorimetre (DSC), thermogravimetry analysis (TGA), heat deflection temperature (HDT), thermal mechanical analysis (TMA), Fourier transform infrared (FTIR) spectroscopy analysis, field emission scanning electron microscopy. The morphological studies revealed a homogenous dispersion of GNPs in PP/KF/MAPP/GNP up to 3 phr loading after which agglomeration occurred. Flexural strength and modulus were enhanced by 70% and 98% respectively at 3 phr GNPs loading which were the highest values obtained. Interestingly, the highest value for the impact strength was also recorded at 3 phr loading. Thermal conductivity increased by 88%, CTE decreased by 80%, water absorption and thickness swelling decreased while HDT improved. The thermal stability of the composites were generally improved at all GNP loading with the highest at 3 phr. From the overall results, it is obvious that the optimum concentration of GNPs in the PP/KF/MAPP/GNP system in terms of both mechanical and thermal properties was 3 phr loading. Although, the mechanical and thermal properties of the composites were improved, the FTIR analysis did not reveal any chemical interaction between GNP and the PP/KF/MAPP system