Abstract: Structural uses in the vehicle, aerospace, and sporting goods industries are being supplanted by hybrid composites that utilized natural fibers as reinforcements. The main focus of this work is to fabricate and characterize the ramie, hemp, and kevlar fabric reinforced hybrid vinyl ester composites. The composite laminates were fabricated via economically feasible and flexible hand lay‐up technique. Overall six composites were prepared by varying the stacking sequence, including both hybrid and non‐hybrid composites. The prepared composites were subjected to physical analysis (density, void fraction), mechanical tests (tensile, flexural, interlaminar shear, and impact test), morphological analysis (scanning electron microscopy), and water absorption test. The hybrid composites exhibited lesser void percentage than the non‐hybrid composites. The mechanical properties were maximum for kevlar fabric skinned with core natural fabric reinforced composites (L‐5, L‐6) due to hybridization of highly strengthened kevlar fabrics. Moreover, the number fabric layers reinforced to achieve the standard thickness also affected the mechanical properties. All composite morphologies exhibited the same failure characteristics, including transverse interlaminar shear cracking, microbuckling, and fiber rip. The texture of the Kevlar yarns is uniform, but the texture of the natural fabric yarns is relatively less uniform. In comparison to the salt water medium, the percentage of water absorbed by composites in normal and distilled water was greater. This is due to the presence and accumulation of salt particles on the surface of the materials, which inhibits the action of water molecules, resulting in a drop in the proportion.

Abstract: This study provides an overview of the rheological properties of aqueous polyurethanes (WPU), as the main component, or as a thickening additive in aqueous formulations. Waterborne polyurethanes (WPU) have been proposed as an environmentally friendly alternative to conventional solvent‐based solutions in a variety of industrial applications such as coatings, adhesives, inks. In all these fields, the control of rheological properties became an important prerogative to determine the quality of the dispersion and its potential applicability. First, the effect of parameters such as components, particle size and content, temperature, and interactions on dispersion viscosity was reported. Then, the effect of two additives, i.e. thickeners and nanomaterials, on structure–property relationships of WPU‐base systems, was described. Thickeners are rheological modifiers, commonly used to stabilize the dispersion and prevent flocculation and sedimentation of the particles, or to change the flow behavior of dispersions from Newtonian to pseudoplastic. These species can interact with water and polymer particles to create a network structure that alters the flow resistance, and thus viscosity. The use of hyperbranched aqueous polyurethane as thickening agent in WPU formulations was also presented. On the other hand, nanostructured fillers (0D/1D/2D) or a combination thereof in waterborne polyurethane led to the formation of specific microstructures that prevented the penetration of water, oxygen, and corrosive substances, also improved mechanical and thermal properties, allowing the development of high‐performance WPU‐based products.

Abstract: Due to the novel physicochemical properties of polymeric nanocomposites (PNCs), a remarkable role of PNCs has been accomplished in plenty of flexible optoelectronic applications. Solution cast procedure has been performed to prepare different contents (0.1, 0.5, 1.0, 5.0, and 10 wt%) of Ag1.6Cu0.2S (ACS) incorporated in PVP/PVA blend. Fourier transforms infrared and scanning electron microscope measurements were carried out to investigate the influence of ACS on PVP/PVA structure and morphology. UV–visible spectrophotometry technique was applied to examine PVP/PVA optical properties modifications. Spectroscopic analysis reveals that direct/indirect optical bandgap of PVP/PVA host shrinks from 5.21/4.95 eV (PVP/PVA0) to 4.87/4.54 eV (PVP/PVA10). Moreover, obvious enrichments in the whole linear/nonlinear optical parameters are achieved by ACS doping. For example, refractive index and dielectric constants of PVP/PVA are increased from 1.69 and 2.87 to 1.91 and 3.63 (PVP/PVA10). While two orders of magnetite enhancement in nonlinear third‐order susceptibility are achieved via 10% ACS doping. The electrical performance of ACS PNCs has been explored, which discloses remarkable enrichments in PVP/PVA DC‐electrical conductivity ( σDC ) and activation energy. The obtained structural, spectroscopic and electrical investigations prove that ACS PNCs could play an efficient role in plenty of optoelectronic applications.

Abstract: Hydrogels are multifunctional engineering materials best known for their promising characteristics such as toughness, flexibility, water absorption capacity, and porosity. These features can support fire protection missions. Application of hydrogels as flame‐retardant materials is receiving much attention, such that several research and industrial projects have been devoted to design, manufacturing, and optimization of flame‐retardant hydrogels—taking a unique position among advanced multifunctional materials and strategies. Likewise, aerogels (derived from gels) due to their porous structure filled with a gas, usually air, rather than water in the case of hydrogels, have shown superior thermal insulation potential. Correspondingly, they have been used in fire and flame protection applications. In this work, the flame‐retardant hydrogels and aerogels along with mechanisms underlying their flame retardancy are reviewed. Besides classifying and interpreting the open literature on flame‐retardant hydrogels and aerogels, challenging aspects of future developments ahead of these advanced materials are highlighted.

Abstract: Plasticizers are widely used in poly(vinyl chloride) (PVC), polylactic acid (PLA), thermoplastic starch (TPS), and other modified powder materials to enhance the flowability, flexibility, and processability of macromolecules. Because of the reprotoxicity of phthalates in animals and humans, certain phthalates have recently been banned in the United States and Europe. Biobased plasticizers from green biomass–derived renewable resources with low toxicity are expected to be a substitute for phthalates. Among a variety of newly developed biobased monomers, cardanol, and isosorbide are the two most promising materials because of their unique structural features. This review summarizes the research progress of cardanol‐ and isosorbide‐based plasticizers with synergistic effects of plasticization, thermal stabilization, and anti‐migration. By summarizing and analyzing the relationship between molecular structure of plasticizer and plasticizing performance, this review can provide theoretical guidance for future research on the design of isosorbide‐ and cardanol‐based plasticizers. Biobased plasticizers with low toxicity are expected to replace certain phthalates. The plasticizing effect of single biobased plasticizer is not good. Biobased plasticizer with synergistic effects is required. There exists the trade‐off effect between the molecular weight and the compatibility. Epoxidized isosorbide ester can be used as a heat stabilizer.

Abstract: Biocompatible polymers such as poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) are used to prepare hydrogels for biomedical applications, including optical applications such as the manufacture of sensing devices, cosmetic and smart, and medical contact lenses, among others. In this study, three contact lenses were prepared by doping PVP-PVA supportive hydrogel with 0.1, 0.5, and 1 wt% of laboratory-manufactured Ag NPs. The work demonstrates the evaluation of vision correction through each lens and the effect of changing the concentration of silver on its refractive index. The simulation involved the design and simulation of an aberrated human eye based on the Liou and Brennan model (LBM), and the insertion of the contact lenses for vision correction using the ZEMAX optical design program. This work also included a study of the antimicrobial properties of the resulting hydrogel contact lenses doped with Ag NPs. The resulting refractive index of one PVP-PVA-Ag lens was relatively high at 532 nm = 1.604, which made the lens provide the highest image contrast (the lowest MTF curve degradation) of 0.883 ± 0.027 at 20 cycles/mm and an RMS nearly the Airy disc diameter of 3.983 μm. PVA was used in combination with PVP for stabilizing Ag NPs to give the contact lenses an antibacterial property. Finally, the optimum contact lens with a 1 wt% Ag NPs concentration showed the highest inhibition activity.

Abstract: Nanocellulose (NC), due to its sustainable nature, high aspect ratio, superior mechanical strength, and availability of functionalizable OH groups, has been widely utilized as reinforcement in numerous fluids/plastics. The physico‐chemical properties of NC, like surface characteristics, dimensions/aspect ratio and their concentration, significantly impact the interparticle interactions, such as the extent of hydrogen bonding, van der Waal forces, hydrophobicity, electrostatic attraction/repulsion, and cellulose entanglement, and have been found to play a critical role in regulating the overall rheological characteristics of fluids. The functionalized NC aqueous suspension exhibited unique shear thinning properties, thixotropic behavior, and quick steady‐state viscosity recovery and viscoelastic properties. However, upon adding functionalized NC to other fluids, a different impact was noticed. For instance, it improved the viscosity, G′ and mechanical stability of bio‐ink; the setting time and mechanical strength of cementitious fluids; increased the filtration performance and provided a unique thermo‐thickening impact in case of water‐based drilling‐fluid; enhanced viscosity with time and heat in case of oil recovery, and so forth. Keeping in view the notable dependence of the rheology of fluids on NC additives, in the present review article, the impact of various physico‐chemical properties of NC additives on the rheological behavior of NC aqueous suspension and its utility as a rheology modifier in multiple advanced fields has been explored. This review article, compared to previous studies, warrants an update on the impact of recent NC surface functionalization/blending techniques employed and NC aspect ratio on specific properties of multiple advanced fluids.

Abstract: Low flame retardant efficiency and poor acid resistance of filled polymer composites are two main drawbacks of magnesium hydroxide (MH) as a flame retardant (FR). To solve these problems, expandable graphite (EG) and microencapsulated red phosphorus (MRP) were introduced into polypropylene/magnesium hydroxide (PP/MH) composite by melt compounding. The obtained PP/MH/EG/MRP quadruple composite was studied regarding its fire behavior as well as acid resistance. Obvious flame retardant synergism among MH, EG, and MRP is found in PP, which diminishes the loading of FR from 63.0 to 37.5 wt% to obtain V‐0 rating in UL‐94 test and low smoke release. Compact intumescent char with high thermo‐oxidative stability was generated on composite surface, which plays a vital role in flame retardancy. The removal of MH by acid erosion on PP/MH/EG/MRP composite surface does not affect production of intumescent char and fire behavior of this composite. The composite displays good fire retardancy, smoke inhibition, and acid resistivity concurrently. This article renders an easy and cheap route to overcome the main faults of MH.

Abstract: Fluorescent polymers have exciting applications in sensing, imaging, and probes. Agricultural waste is increasingly being used to develop fluorescent nanomaterials due to technology, cost, and waste management advantages. This study developed fluorescent carbon‐based nanomaterials, that is, potassium doped graphene oxide (K‐GO) from Quercus ilex waste and used them to optimize fluorescent epoxy nanocomposites. The resulting nanocomposites showed significant enhancement in tensile strength with only 0.05 wt% of the renewable nanomaterial. The developed fluorescent epoxy nanocomposites have enhanced thermal and mechanical properties and can be used in sensing, imaging, and other applications.

Abstract: The aim of the present research was to synthesize and characterize polyvinyl alcohol/dextran/Zataria essential oil hydrogel wound dressings. For this purpose, dressings were made with different concentrations of polymers (PVA and Dex) and ZMO by solvent casting method. By dissolving PVA and Dextran in de‐ionized water, PVA‐Dex gel was made. The polymeric solution was mixed with glycerol. The pH of PVA‐DEX‐Glycerol solution was adjusted to 3 and glutaraldehyde was used as a cross‐linker. ZMO, as the antibacterial and antioxidant agent, was added to the samples in different percentages (2,5,10%). It was found that both Dex and ZMO significantly influenced the hydrophilicity, gel fraction, and water uptake capacity of hydrogel films. The results showed that by the addition of Dex to PVA, the contact angle decreased from 48.54° ± 0.95 to 45.90 ± 0.73°, whereas by the addition of ZMO, the contact angle increased to 71.1 ± 2.43. SEM investigations revealed that the fabricated films had a uniform structure and the surface roughness increased with the addition of ZMO. The results indicated an increased elongation of 11.5% with the incorporation of ZMO into the films. The antimicrobial evaluation of the produced films showed that the loading of 10% v/v ZMO could broaden the microbicidal activity of PVA/Dex/ZMO film. The investigations on the interactions between synthesized wound dressings and fibroblast cells showed that the addition of ZMO into hydrogel films improved cell viability. The findings showed that PVA/Dex/ZMO films could have considerable use as wound dressing.

Abstract: Vat photopolymerization (VP) and direct ink write (DIW) additive manufacturing (AM) provide complex geometries with precise spatial control employing a vast array of photo‐reactive polymeric systems. Although VP is recognized for superior resolution and surface finish, DIW provides versatility for higher viscosity systems. However, each AM platform presents specific rheological requirements that are essential for successful 3D printing. First, viscosity requirements constrain VP polymeric materials to viscosities below 10 Pa s. Thus, this requirement presents a challenging paradox that must be overcome to attain the physical performance of high molecular weight polymers while maintaining suitable viscosities for VP polymeric materials. Second, the necessary rheological complexity that is required for DIW pastes requires additional rheological measurements to ensure desirable thixotropic behavior. This manuscript describes the importance of rheological measurements when designing polymeric latexes for AM. Latexes effectively decouple the dependency of viscosity on molecular weight, thus enabling high molecular weight polymers with low viscosities. Photo‐crosslinking of water‐soluble monomers and telechelic oligomeric diacrylates in the presence of the latex enables the fabrication of a scaffold, which is restricted to the continuous aqueous phase and effectively surrounds the latex nanoparticles enabling the printing of otherwise inaccessible high molecular weight polymers. Rheological testing, including both steady and oscillatory shear experiments, provides insights into system properties and provides predictability for successful printing. This perspective article aims to provide an understanding of both chemical functionality (photo‐ and thermal‐reactivity) and rheological response and their importance for the successful design and evaluation of VP and DIW processable latex formulations.

Abstract: As a green material for high‐performance paving, cold‐mixed epoxy asphalt (CEA) should be improved in compatibility, mechanical performance, and thermal stability. This work is going to estimate the potential of graphene oxide (GO) as an additive for preparing GO/CEA composites with different GO content from 0 to 0.2 wt%. The influences of GO on the structure and performances of CEA were evaluated by Fourier transform‐infrared spectrum, fluorescence microscopy, viscosity, thermogravimetric analysis, tensile test, and dynamic mechanical analysis. Results showed that the functional groups on GO reacted with CEA and improved the compatibility of epoxy resin and asphalt. The viscosity of the GO/CEA composites increased slightly and the pot life decreased significantly, with GO loading increasing. The cured GO/CEA composite with 0.1 wt% GO had the best heat resistance and showed a gentle thermal decomposition. GO improved the toughness of the cured CEA and had a certain weakening effect on its strength. The introduction of GO lowered the glass transition temperature of the cured CEA from 51.4 to 47.1 °C and decreased its storage modulus. The preliminary exploration of this study shows that the modification of GO for CEA is feasible, and it is expected to prolong the service life of CEA.

Abstract: Exploiting high phosphorus content of phytic acid, it was grafted onto magnesium hydroxide (MH) by neutralization reaction to obtain MGPA, a flame retardant. A current study investigated the effect of MGPA on hydrophobicity, flame retardancy, and mechanical properties of MGPA‐linear low‐density polyethylene (LLDPE) composites. The LLDPE composite with 50 parts of MGPA has the better flame retardancy and thermal stability with a limiting oxygen index of 23.3%, which is higher than that of neat LLDPE (17%). In addition, MGPA could effectively promoted LLDPE to form a continuous and compact char residue during combustion, which reduce the peak of heat release rate and total smoke production value of LLDPE composite by 70% and 36%, respectively, and the char residue rate increase to 67.5%. Furthermore, the maximum of loss‐rate showed by LLDPE composite with MGPA reduce to 1.25%/min while the value of LLDPE composite with MH is 1.8%/min. Meanwhile, the LLDPE composite with MGPA show remarkable elongation at break and hydrophobicity, which are 398% and 99°, respectively. In addition, this study presents a substantial flame retardancy and interfacial compatibility of MGPA for extending the applications of flame‐retardant LLDPE composites.

Abstract: For the first time, a novel nanohybrid based on nickel phosphide (Ni2P) nanoparticles and molybdenum disulfide (MoS2) nanosheets was facilely synthesized for enhancing flame retardancy and smoke suppression of thermoplastic polyurethane (TPU). The synergistic effect on flame retardancy is proposed. TPU composite with 2 wt% Ni2P/MoS2 hybrid exhibits the best overall flame retardancy, while TPU composites with the same amount of individual Ni2P nanoparticles and MoS2 nanosheets are average in performance. Specifically, the 41.2% reduction of peak heat release rate (PHRR) is achieved for TPU/Ni2P/MoS2 composite, which is only 16.8% and 26.4% for TPU/Ni2P and TPU/MoS2 composites, respectively. In addition, a more intact protective char layer of TPU/Ni2P/MoS2 composite can be observed. These results clearly suggest the synergistic effect between Ni2P nanoparticles and MoS2 nanosheets. It is hypothesized that physical barrier effect and chemical catalytic ability of Ni2P/MoS2 hybrid contribute to the dramatic reduction of heat release and smoke production. The strategy proposed here is a simple yet efficient approach to fabricate high‐performance MoS2‐based flame retardants.

Abstract: Graphite is a thermally conductive filler. However, when dispersed into high density poly(ethylene) (HDPE) resin, graphite particles tend to agglomerate and requires a compatibilizer to achieve desired thermal/physical properties. In this study, oleic acid (OA), a bio-based additive and polyethylene-polyamines (PEPA) were used to synthesize a new compatibilizer, PEPA-g-OA, containing numerous NR2 groups. The experimental results showed that PEPA-g-OA can significantly improve the compatibility between graphite particles and the HDPE matrix due to uniform dispersion of graphite in the HDPE matrix. When the graphite content was 25 wt%, the thermal conductivity of the composite recorded 1.2 W m−1 K−1 (three times that of neat HDPE) and the volume resistivity was 1.8 × 109 Ω cm, indicating excellent electrical insulation. Compared to the composites with no graphite content, the properties of the composites with 25 wt% graphite content exhibited narrower melting and crystallization peaks, more stable mechanical properties, and higher ultraviolet aging resistance. Synthesized new bio-based compatibilizer and thermally conductive and electrically insulating composites developed in this study can be useful in different industrial fields for the preparation of the next generation composites.

Abstract: In this study a highly flexible microwave shielding material was fabricated by solution casting method utilizing Nickel and biocarbon particles in PVA matrix and characterized for mechanical, magnetic, and microwave shielding properties. The main aim of this study was to prove the significant role of magnetic particles in electromagnetic interference (EMI) shielding along with conductive particles. The results show that the addition of Ni‐biocarbon hybrid particle increases the shielding properties up to 56.5 dB at 20 GHz. The magnetic permeability increased gradually with the inclusion of Ni particles with a highest magnetization, coercivity, and retentivity of 1250 E−6 emu, −9000 G, and 1100 E−6 emu. Similarly the mechanical results show that adding biocarbon enhances the composite's mechanical properties. A highest tensile strength, tear strength, elongation, and hardness are noted as 38, 168 MPa, 18.4%, and 36 Shore‐D. Comparatively, the hardness and elongation% of composite designations contains 3 and 5 vol% of hybrid particles have increased by 9% and 26%, respectively, in comparison to composite containing only 5 vol% of biocarbon with PVA. Scanning electron microscope fractography indicates biocarbon particles reduce voids and improve adhesion. These flexible EMI shielding composites could be used in telecommunication and other wave transmitting devices in engineering applications.

Abstract: Smart packaging relies on the one-to-one interaction of food with its packaging or its environment to monitor food quality and safety. Colorimetric pH indicators (synthetic, natural) working in a smart food packaging system are particularly striking when used with fresh foodstuffs such as fish and meat that perish quickly and require real-time freshness monitoring. In this study, curcumin (Cur) was used as a natural pH indicator to produce sustainable smart packaging material. Towards this objective, low-density polyethylene (LDPE) and thermoplastic starch (TPS) blend-based films containing Cur were prepared using a twin screw extrusion and hot-pressing processes. Besides, two different compositions of LDPE/TPS mixture (50/50 and 70/30) were used as the matrix. Thermal, mechanical, morphological properties, an affinity for water, and color change properties of LDPE/TPS/Cur films were investigated. They showed a significant color change from yellow to brown at pH: 10 at the end of the seventh day, especially in the 50 LDPE/50 TPS mixture. 50 LDPE/50 TPS mixture with 7% curcumin content gave the highest tensile strength of 8.03 Mpa. When the same mixture was used to monitor chicken meat spoilage at 25°C, meat samples have shown color changes from light yellow to light brown due to the increased content of total volatile basic amines. As a result, it has been suggested that 50 LDPE/50 TPS mixture containing 7% Cur can be used as a smart packaging material.

Abstract: Polypropylene (PP) was modified by expandable graphite (EG) and magnesium hydroxide (MH) to enhance its flame retardancy. The impact of EG particle size on fire behavior of PP/MH/EG ternary composite was studied in detail. The results reveal that EG synergizes markedly with MH in flame‐retarding PP. The PP/MH/EG composite with larger EG particle size displays better flame retardancy, smoke inhibition, acid resistivity, processability, and less toxic gas release upon combustion. The striking contrast derives from differences of charring behavior in condensed phase. The composite with larger EG particle size can produce intumescent char with larger expansion volume and better compactness and continuity, which hinders heat transfer inside polymer composite. Owing to much smaller expansion volume, the composite containing smaller EG particle size cannot generate effective fireproof barrier. As a consequence, this composite exhibits worse fire retardance and smoke inhibition in contrast with the composite with larger EG particle size.

Abstract: Layered double hydroxide (LDH) is a widely used flame retardant in polymer materials; however, the poor dispersion due to its high hydrophilic nature results in disappointing thermal stability and fire safety. In this work, LDH was in‐situ grown on the disordered montmorillonite (MMT) nanosheets to obtain the hybrid of LDH and MMT nanosheets (LDH@MMT, simplified as LM). Various techniques, including X‐ray diffraction, Fourier‐transform infrared spectroscopy, field emission scanning electron microscopy, and transmission electron microscope were used to characterize the microstructure of LM. In addition, the acrylonitrile‐butadiene‐styrene (ABS) composite containing LM and intumescent flame retardant (IFR) was prepared, and its mechanical and flame‐retardant properties were also measured. The characterization results demonstrate that the LM exhibits a periodically alternating layered structure. The Limiting Oxygen Index (LOI) of the ABS composite reaches 27.2% with a V‐0 rating in the UL‐94 vertical burning test, while its flexural strength and tensile strength decrease by only 17.82% and 13.45%, respectively. Furthermore, the heat release rate, total heat release, smoke production rate, and carbon monoxide production rate of the ABS composite present a significant decline in cone calorimeter tests compared with those of pure ABS. The results further indicate that the hybridization could effectively improve the flame‐retardant performance of ABS composites and perform lesser impacts on their mechanical properties.

Abstract: Hydrogel beads are emerging as alternate adsorbent material for the batch or continuous column treatment of dye wastewater. Polysaccharide‐based gel beads are preferred for their uniform shape and size, large specific surface area, and easy separation by filtration and subsequent reuse. In this work, we prepare and rheologically characterize UV‐active κ‐carrageenan/TiO2 beads for the adsorption and degradation of dyes. The 3–4 mm sized nanocomposite beads are formed by the extrusion of κ‐carrageenan/TiO2 gel solution in salt solutions. The maximum increase in modulus was observed with the addition of 1% w/v TiO2 to κ‐carrageenan and subsequent crosslinking with mixed salt of KCl and CaCl2. κ‐carrageenan/TiO2 beads crosslinked by mixed salt of KCl and CaCl2 have higher adsorption capacity, as compared to beads crosslinked with single salt of KCl. The kinetic study indicated the chemisorption of Methylene Blue on the bead surface. κ‐carrageenan/TiO2 beads showed higher degradation for Methylene Blue and Nile Blue A than Rhodamine B in 5 and 50 ppm each multicomponent dye systems under UV irradiation. The κ‐carrageenan/TiO2 beads could form a porous column for the selective adsorption of positively charged dyes from a multicomponent dye system.

Abstract: Low cost and environment friendly fly ash particles and silica particles were used as additives in the rigid polyurethane foam composite. The usage of fly ash will decrease the need for its handling and exposure to environment. FTIR spectra show the absence of hydrogen bonded urea which indicates no aggregation of hard urea domains in the soft polyurethane matrix after the addition of silica/fly ash. The composite loaded with 20 weight percentage fly ash had the highest glass transition temperature. At 10 weight percentage of the additive, the gross calorific value in the fly ash loaded composite decreased by 12% when compared with the composite loaded with silica. Introduction of fly ash into the foam composite up to a certain weight percentage (10 wt%) enhanced the compressive strength of the rigid polyurethane foam composite. The percolate particle concentration was at 10 weight percentage of the additive. The addition of fly ash increased the compressive strength up to 21% compared to the foam composite loaded with silica. Addition of fly ash in the foam composite resulted in a decrease of water absorption up to 23% in comparison to the composite loaded with silica. Hence, low cost and environment friendly fly ash is suitable additive which can be loaded into rigid polyurethane foams for superior enhancement in mechanical and thermal properties.

Abstract: Nowadays, one of the design direction of bio-derived and biodegradable polymer foams with multi-functionalization is how to attain superior electromagnetic interference (EMI) shielding property, which has become a hot topic. Herein, bio-based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) foams filled with carbon nanotubes (CNTs) and/or graphene nanoplatelets (GNPs) were fabricated by supercritical carbon dioxide. As observed by optical microscope and scanning electron microscope, the CNTs and GNPs in PHBV matrix might gradually construct three kinds of network structures (CNTs-CNTs, GNPs-GNPs and GNPs-CNTs network structures), which would improve the melt viscoelasticity, crystallization, electrical, dielectric and EMI shielding properties of PHBV. The complex viscosity and storage modulus of PHBV nanocomposites with the ratio of CNTs/GNPs as 1:1 rose nearly three orders of magnitudes than those of pure PHBV, in addition, its crystallization temperature and crystallinity increased remarkably to 122°C and 62%, individually. When the CNTs/GNPs ratio was 1:1 at a low total content of 3 wt%, PHBV nanocomposite and its foam implemented the high dielectric properties. Furthermore, the EMI specific shielding effectiveness of obtained PHBV was blend with 1.5 wt% CNTs and 1.5 wt% GNPs nanocomposite foam was the highest, reaching 19.3 dB cm3/g. This work paved a feasible way to the production of eco-friendly PHBV nanocomposite foams for the application of electronics and aerospace industries. Highlights PHBV/CNTs/GNPs foams were prepared using a scCO2-assisted foaming method. Dispersion of carbon fillers in PHBV was the best as CNTs/GNPs ratio was 1:1. G' of PHBV/C1.5/G1.5 specimens were increased by three orders of magnitude. EMI specific shielding effectiveness of PHBV/C1.5/G1.5 nanocomposite foam could reach 19.3 dB cm3/g.

Abstract: In this work, a strategy was used to combine Mg(OH)2 nanoparticles (MDH), the bentonite nano-sheets, and melamine cyanurate (MC) to prepare dioctyl phthalate (DOP) plasticized polyvinyl chloride (PVC) nanocomposites with increased thermal stability, Limiting Oxygen Index (LOI), and tensile strength as well as reduced total heat release. To prepare MC-modified Mg(OH)2@bentonite nanohybrid (MMHB), MDH was installed on the calcined bentonite and consequently modified with MC. The nanocomposite thin films were prepared from plasticized-PVC and MMHB using the solvent casting method. It was found that the combination of MDH and the bentonite nano-sheets in the presence of MC could improve the PVC properties. Thermogravimetric analysis (TGA) in both N2 and air atmospheres, indicated that the thermal stability of PVC was enhanced via adding MMHB, which was evident by the increased thermal decomposition temperature. The microscale combustion calorimetry (MCC) results of the PVC nanocomposites with 5% and 8% by mass of MMHB revealed that an optimal isolating layer is formed, which increased flame retardant properties. The PVC matrix nanocomposite containing 8% by mass of MMHB with LOI value of 33.4% exhibited high flame retardancy. Moreover, the tensile strength and elastic modulus of the sample containing 5% by mass of MMHB increased by 65.5% and 55.2% compared to those of pristine PVC, respectively. Highlights A nanohybrid was prepared from Mg(OH)2 (MDH) and calcined bentonite. Preparation of melamine cyanurate (MC). Preparation of MC-modified [email protected] nanohybrid (MMHB). Effects of MMHB on thermal stability and flame retardancy of plasticized PVC. The efficient flame retardancy effect of the additive on plasticized PVC.

Abstract: Undoped and doped polyvinyl chloride (PVC) with zinc, nickel and cobalt oxides, ZnO/[(1−x)NiO/xCo3O4], composites were fabricated using co-precipitation and casting techniques. The different phases present in the nanofiller ZnO/[(1−x)NiO-xCo3O4] mixed oxides were determined using synchrotron x-ray diffraction technique. X-ray diffraction, scanning electron microscopy (SEM) images and energy dispersive spectroscopy (EDS) analysis techniques were used to investigate the structure, composition, and morphology of pure and loaded PVC with nanofiller oxides. In general, compared with pure PVC, the absorbance was greatly enhanced, especially in the UV region, upon loading ZnO/[(1−x)NiO-xCo3O4], but it changed irregularly with the cobalt oxide (Co3O4) content (x). The direct and indirect optical band gaps of pristine PVC (4.14, 4.12 eV) reduced irregularly to minimum values 3.97 and 3.23 eV respectively for the polymer doped with ZnO/[0.3NiO/0.7Co3O4]. The refractive index was enhanced in the visible and IR regions and attained its highest value for PVC doped with zinc oxide/nickel oxide (ZnO/NiO) only (x = 0.0). NiO and Co3O4 ratios affect the linear and nonlinear optical parameters. The emitted spectra from pure and doped PVC polymers with the composite oxides [ZnO/[(1−x)NiO-xCo3O4] under different excitation wavelengths were also explored. The FL intensity enhanced for the excitation wavelengths (λexc) = 380 and 434 nm but quenched for λexc = 317 nm. The loaded polymers absorb UVA, UVB, and UVC rays and are good candidates for solar cell applications.

Abstract: Titanium dioxide (TiO2) has a strong oxidation effect when absorbing ultraviolet light. Therefore, when TiO2 is used as a light stabilizer in polyvinyl chloride (PVC), it will cause the photodegradation of PVC. Herein, carbon quantum dots (CQDs) coated TiO2 composite (TiO2@CQDs) was prepared by a one-step hydrothermal method. The prepared TiO2@CQDs were characterized by transmission electron microscopy (TEM), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The photostability of PVC film containing TiO2@CQDs was investigated via photodegradation conductivity test, weight loss rate test, and ultraviolet aging test. Due to the down-conversion effect of CQDs under ultraviolet light, its existence can alleviate the photoaging of PVC. In addition, the thermal stability of PVC containing TiO2@CQDs was studied by conductivity tests and oven thermal aging tests. The presence of CQDs significantly improved the thermal stability of PVC. Meanwhile, the HCl absorption capacity of CQDs could reach 30.8 mg/gcat. According to the DFT calculations, this high absorption capacity is attributed to the HCl immobilization effect via forming hydrogen bonds between HCl and the keto oxygen, carboxyl keto oxygen in CQDs. The hydroxyl group in CQDs could also combine ZnCl2 by forming a coordination bond.

Abstract: This study focused on the development of three-dimensional (3D) polymer composite filament made of disposable chopstick (DC) and post-consumer polypropylene (PPP). The PPP/DC composite parts were printed via fused filament fabrication (FFF) process. The effect of the printing temperature and different DC fiber content on the properties of the 3D printed parts were investigated. The printing temperature of 200–220°C was suitable for these filaments because the printing temperature did not show any thermal degradation, as proven by thermogravimetric analysis. Furthermore, the thermal stability of the 3D filament increased with DC content. The chemical modification with sodium hydroxide (NaOH) was carried out on DC to remove the unwanted organic components by showing changes in peak intensity in the Fourier transform infrared analysis. Moreover, the melt flow index of the composite filaments decreased with increasing of the DC content and caused the composites' viscosity increased. The results show that the optimum printing temperature of 210°C would reduce the warping and gave better tensile properties to the 3D printed parts. Nevertheless, the tensile strength and elongation at break of the 3D printed PPP/DC parts reduced as the DC content increased because the presence of some air gap and fiber pull out on the fracture surface of 3D printed parts, which are in line with the results observed from scanning electron microscopy. However, the tensile strength and elongation at break percentage of all 3D printed PPP/DC composite parts were higher in comparison with the 3D parts printed by commercial wood plastic composite filament.

Abstract: This study aimed to reveal the effect of expanded perlite (EP) additive as a flame retardant for acrylonitrile‐butadiene‐styrene (ABS) copolymer based composites. Before composite preparation, fine powdered EP was characterized by Fourier transform infrared spectroscopy, x‐ray diffraction, thermogravimetric analysis, and scanning electron microscopic analyses. Also, maleic anhydride grafted ABS (MAH‐g‐ABS) with a grafting degree of 3.9 wt% was synthesized and used as a polymeric compatibilizer. ABS/EP composites with different ratios of EP were prepared by a continuous one‐step melt mixing method. Thermogravimetric and morphological analysis, tensile tests, limiting oxygen index (LOI) and UL‐94 vertical burning tests of the composite materials were investigated. EP significantly decreased the decomposition rate of ABS and promoted char formation. EP provided a UL‐94 V‐1 flammability rating with great fire resistance and self‐extinguishing properties to the ABS matrix without any melt dripping. The LOI of ABS was greatly improved, reaching a value of 28.5% by adding only 5 phr EP. Zinc borate (ZB) also played a significant role in enhancing thermal stability and flame retardancy by creating a good synergism with EP. The composite containing 5 phr ZB showed a flame retardant grade of UL‐94 V‐0 and an LOI value of 27.5%. Flame retardant ABS/EP composites were successfully prepared by melt mixing. The EP ratio of 10 phr provided the highest resistance to flammability. ZB showed good synergy with EP in enhancing the flame retardancy of ABS. ABS/EP10/ZB‐5 composite had a UL‐94 V‐0 rating with an LOI value of 27.0%. This study proved the potential use of natural EP as a flame retardant filler.

Abstract: To effectively reduce the fire hazard of flexible polyvinyl chloride (PVC), this study explored the synthesis of perovskite-type copper hydroxystannate (CuSn(OH)6) microspheres by co-precipitation method. Then an organic–inorganic hybrid microsphere (CuSn(OH)6@PZS) with core-shell structure was fabricated by in situ coating with poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS). The results showed that CuSn(OH)6@PZS performs most significantly in reducing the total heat release, while the CuSn(OH)6 alone achieves the best smoke suppression effect. The limiting oxygen index (LOI) value of the PVC composites is improved from 29.0% to a maximum of 35.3%. During combustion, the peak heat release rate (PHRR) and total smoke production (TSP) decrease by a maximum of 50.8% and 44.9%, respectively. Significantly, the presence of the PZS coating also improves the interfacial compatibility with PVC. The mechanical properties were significantly improved and the elongation at break improving by 40.9%.