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In this study, the potential use of nanocrystalline cellulose (CNC) modified epoxy nanocomposite as a matrix is investigated for both glass and carbon fiber-reinforced composites. Various amounts of CNCs (1, 2, 4, and 6 wt%) were added to bisphenol A diglycidyl ether-based epoxy resin (DGEBA), and the optimum CNC loading was determined as 4 wt% in terms of mechanical and thermal properties. Compared to the reference sample containing a neat epoxy matrix with the obtained carbon fiber/CNC-epoxy (CNC/epoxy/CF) and glass fiber/CNC-epoxy (CNC/epoxy/GF) hybrid nanocomposites, significant improvements have been determined in the in-plane shear modulus and strength, and flexural modulus, respectively. The mechanical properties improvements of CNC/epoxy/CF hybrid composites are approximately 0.9% higher than the CNC/epoxy/GF hybrid composites. Additionally, the distribution of CNC in hybrid nanocomposites is also investigated by scanning and transmission electron microscopies. It is noted that the homogenous dispersion of CNCs in the epoxy matrix and their diameters varied from 10 to 100 nm are detected at higher magnification.

Silicone foam (SF) is a porous silicone rubber with a lower density, higher elasticity, and good thermal stability. In this work, we selected aluminum spheres and carbon fiber (CF) as thermally conductive fillers to prepare hybrid SF. After optimization, we found that Al and CF hybrid SF (Al-CF-SF) has a higher thermal conductivity (1.37 W·m–1·K–1) than the single-filler filled SF (CF-SF, 1.2 W·m–1·K–1 or Al-SF, 0.52 W·m–1·K–1) under the same filling amount of 60 wt%. The finite element simulation was used further to explore the thermal conductive mechanism of the hybrid SF. Meanwhile, the compressive and tensile modulus of the material (CF-SF) was increased to 10.8 and 3.3 MPa compared with pure SF, respectively, and the mechanical properties were improved. In addition, infrared thermography further demonstrated that Al-CF-SF has a faster heat transfer rate under relaxation and applied pressure.

In recent years, solid polymer electrolytes (SPE) has attracted much attention because of its good safety and environmental stability, among which poly(ε-caprolactone) (PCL) based solid electrolyte film is one of the most potential materials. We have adopted the method of synthesizing polymer nanocomposites with natural clay, which can effectively meet the needs of electrolytes. In this study, cetyl trimethyl ammonium bromide (CTAB) was used to modify rectorite (REC), and the ε-CL monomer is inserted between the rectorite silicate layers. PCL/organic rectorite (OREC) nanocomposites were synthesized by in situ intercalation polymerization. The yield of the polymer nanocomposite could reach 93.6% when the molecular weight of the polymer nanocomposite was 39 000. The effects of OREC addition on the morphology, thermal stability, and electrochemical properties of PCL/OREC nanocomposites were investigated by various characterization methods. The temperature can be increased by 50 °C when the thermal decomposition is 50 wt%, and the crystallinity decreases by 4.6%. Composite polymerelectrolytes (CPEs) (PCL/OREC) showed a good electrical conductivity of 1.13·10–4 S·cm–1 at 60 °C and an excellent capacity retention rate of 96.7% after 100 cycles at 0.5 C current density. This study has important guiding significance for the development of polymer nanocomposites as solid electrolytes.

Conductive carbon black (CCB), carbon nanotubes (CNT) and its hybrids are introduced into the natural rubber (NR) matrix aiming to explore the effect of filler ratio on the transport properties. Solvent transport of NR is found to decrease for hybrid filler systems as compared to single filler incorporated systems. Kinetic parameters of solvent transport behavior of filled NR systems are analyzed using various kinetic models. Upon the computation of kinetic parameters of transport data, it is found that the Peppas-Sahlin model is in good agreement with experimental observations, which suggests that the transport mechanism is diffusion controlled. Rubber–filler interaction parameters are computed and analyzed from the swelling experiments using Kraus, Cunneen-Russel, and Lorenz-Park equations

Acrylonitrile butadiene rubber (NBR) films filled with zinc oxide (ZnO) were prepared via latex mixing. The ZnO of commercial ZnO (ZnOWH), ZnO nanoparticles (ZnOnap), ZnOnap-coated with calcium carbonate (ZnOnap-C), and titanium dioxide (ZnOnap-T) were investigated, and the mechanical and dynamic mechanical properties, crosslink density, and antibacterial activity of the resultant films were explored. The study found that the particle size and distribution of ZnO in the NBR films played a significant role in enhancing their properties. The incorporation of ZnOnap resulted in a greater enhancement in the properties of the composite film than the ZnOWH microparticles, with the greatest enhancement achieved with ZnOnap-C. Furthermore, the composite films filled with 1 phr of ZnOnap-C exhibited 99.9% bacterial reduction efficacy against Staphylococcus aureus and Escherichia coli according to ISO 22196:2011 due to the release of reactive oxygen species and zinc ions across the rubber film layers to the bacterial surfaces. In addition, the bactericidal efficacy on the surface of the composite films was investigated by varying the contact kill times in accordance with ASTM D7907-14. The addition of ZnOnap-C at 4 phr reduced both bacterial levels by 92.00 and 51.85%, respectively, within 30 min. Hence, this research aims to contribute to developing new medical disinfection products, such as medical gloves and multipurpose rubber sheets.

Spent coffee grounds (SCGs), the main by-product in the coffee industry, were proposed as a starting material to fabricate both ultraviolet (UV) shielding material and nanocomposite based on polyvinyl alcohol (PVA). The extract using low SCGs concentration (0.25 wt%) contains a significant amount of UV-absorbing substances. The UV shielding film from 5 wt% PVA solution and SCGs extract (1 g SCGs/200 ml water) could shield most of the radiation in UV-B and UV-C regions and maintain 63% transmittance at 550 nm. The SCGs after washing were ball milled and the ultrasonic liquid processor was applied to synthesize SCGs nanoparticle. The effects of ultrasonic amplitude and hexadecyltrimethylammonium bromide (CTAB) on the particle’s hydrodynamic diameter were investigated. The particle’s size of 148 nm was obtained with 50% ultrasonic amplitude. Fourier-transformed infrared spectroscopy (FTIR) results confirmed the presence of hydroxyl groups (–OH) on the SCGs-based nanoparticle’s surface. The tensile strength of PVA-SCGs nanocomposite was significantly improved. However, the presence of CTAB in the nano solution could not show a better tensile result. The organic compounds contained in the SCGs extract and even in the nano SCGs solution could enhance thermal oxidation stability for both UV shielding films and nanocomposites.

Solid polymer electrolytes based on polyvinyl alcohol (PVA)–chitosan (CS) polymer blend and Li–salt doped blend electrolyte films are prepared using the solution cast technique. The Fourier transform infrared spectra showed that the absorption peaks shifted in Li–salt doped polymer blend composites compared to pure blend films: indicating the chemical modifications upon doping. From the UV–visible spectra, the spectral absorption response of Li+ salt–doped polymer blend composites showed a red shift in the absorption band. The optical band gap of the pure polymer blend decreased upon doping. X–ray diffraction studies showed the dopant-dependent structural modification of pure polymer blend upon doping. SEM images also showed the change in the surface morphology of the pure polymer blend upon doping. The termogravimetric analysis study revealed that the thermal stability of the pure polymer blend increases with Li2CO3 concentration. The ionic conductivity of PVA–CS increases with Li–salt concentration, and the maximum conductivity of 7.70·10–5 S·cm–1 is observed for 15 wt% of Li2CO3 salt concentration. The transport property study revealed that the ions are the majority conducting charge carriers in polymer blend composite.

The present work reports on the development of environmentally friendly, completely biodegradable wood plastic composites based on polylactide (PLA) and tangerine peel flour (TPF), plasticized by α-terpinyl acetate (TA). The TPF varied in the 10–30 wt% while the PLA to TA (wt%/wt%) was set to 4 (i.e., 25 wt% TA plasticizer was added with regard to the PLA wt%). The developed composites were processed by extrusion and injection molding. The composites presented excellent elongation at break, achieving values of 300% for the PLA+TA sample. Elongation at break values of 200% for the PLA composite with 10 wt% TPF and plasticized with TA were obtained. Those results were confirmed by the appearance of filament-like structures observed in field emission scanning electron microscopy images. Differential scanning calorimetry and dynamic mechanical thermal analysis revealed a remarkable decrease in the glass transition temperature of PLA as a result of the plasticizing effect of TA. Glass transition was reduced from 63°C down to 41°C approximately. This implied an increase in the ductility of the material. The samples with TPF exhibited a dark brown color, making them perfect for wood plastic composite applications. Water contact angle results show that TA and TPF change the wetting properties of the obtained composites. A general decrease in the water contact angle was observed with the addition of TPF and TA. Finally, disintegration tests proved that the developed composites are fully biodegradable. All the samples except for neat PLA achieved 100% disintegration in controlled compost soil conditions after 5 weeks, while neat PLA reached complete disintegration in 6 weeks.

Conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS is the most widely used material in stretchable and flexible electronics not only due to its good electrical and mechanical properties but also its use in numerous biomedical sensing applications. This article investigates the electromechanical behavior of PEDOT:PSS and its nanocomposite thin film. The films were rod-coated on a chemically treated, cost-effective single-component polymer that was previously characterized as an alternative available substrate material for stretchable and flexible microelectromechanical systems (MEMS) based devices. The results show that the films exhibit stable resistive behavior in response to various applied mechanical loads such as stretching, twisting, combined stretching, and twisting and forced vibrations. The films also show good thermal stability at relatively high temperatures. The prepared films also reveal their applicability as thermal actuators. It was also found that adding nanophases of silver material in PEDOT:PSS enhances the performance of thin films. These results also suggest that the rod-coated PEDOT:PSS and its composite thin films may have versatile applications like stretchable, twistable, and vibration-tolerant conductors, thermal actuators, and devices for future low-cost MEMS devices.

Polypropylene (PP) hybrid composites were prepared with talc, a reinforcing filler, and an additional impact modifier. Impact resistance was improved by the use of a traditional elastomer and by the new approach of adding a synthetic polymer fiber, poly(vinyl alcohol) (PVA), in this case. The results showed that the use of PVA is more efficient than that of the elastomer. The latter decreases stiffness considerably, from the 3.5 GPa value of the PP/talc composite to around 1.5 GPa, it does not carry practically any load, and even its impact modification efficiency is somewhat smaller than that of the PVA fibers. On the other hand, PVA increases stiffness to some extent, up to 5 GPa, tensile strength considerably, especially in the presence of a coupling agent, and the large impact resistance of 20 kJ/m2 can be achieved with it at moderate fiber contents. The positive property profile achieved is the result of the local deformation mechanisms occurring in the PP/talc/PVA composites. Properties can be further adjusted to purpose by the application of a functionalized PP coupling agent.

In elastomer science and technology, the advent of vulcanization led to a paradigm change. Despite ongoing research, vulcanization science and technology have a great deal of untapped potential. This article explores how the various vulcanization systems, such as sulfur-based, peroxide-based, and their hybrid systems, would reflect changes in the physiomechanical characteristics of ethylene-propylene-diene monomer (EPDM) rubber with various molecular configurations. This kind of analysis illuminates the characteristics of the crosslinking network established by each vulcanizing technology. Since solid viscoelastic rubbers include a large number of components, it is nearly impossible to evaluate the crosslinking network directly. If all components other than vulcanizing systems remained intact, stress relaxation behavior correlated directly with the crosslinking network inside the samples. In this work, temperature scanning stress relaxation (TSSR), a relatively new technique capable of creating the whole spectrum of stress relaxation, was effectively explored. The findings suggest that sulfur and carbon crosslinks coexist in hybrid systems regardless of the molecular structure of the elastomer, and their synergistic impact is evident. Furthermore, it is clear from the results that the molecular structure of the vulcanizates has an impact on the final properties, such as tensile, compression strength properties and thermal properties of the samples.

Usually, it is difficult to achieve satisfactory fire retardancy of epoxy resin (EP) at low addition by adding inorganic nano-fillers alone. Herein, sepiolite nanofibers loaded with layered double metal hydroxide (a-SEP@LDH) and phosphorus/nitrogen-containing flame retardant nanosheets (PAMA) were prepared via hydrothermal method, respectively. The UL-94 V-0 rating and an limiting oxygen index (LOI) value of 31.6% were achieved for EP by loading 1 wt% a-SEP@LDH and 2 wt% PAMA. Compared to adding sole a-SEP@LDH, the thermal stability of EP/a-SEP@LDH/PAMA3 was improved significantly, the total heat release (THR) and peak heat release rate (pHRR) decreased by 10.2 and 28.8%, respectively. Additionally, the total CO2 production decreased by 12.5% and the char residue yield increased to 19.9 wt%. Moreover, the tensile strength and impact strength of the EP composites were remarkably improved owing to the incorporation of PAMA. To sum up, this work provides an environmentally benign, low-cost and efficient way for EP to achieve outstanding fire retardance, thermal stability and high mechanical properties at a low addition.

Smart polymers synthesized from renewable sources are precious because of the environmental pressures of producing polymers from fossil fuels. This study develops a new formulation of polyurethane (PU) from partly renewable resources. PU composites were prepared from castor oil (CO), polyethylene glycol (PEG3000), and hexamethylene diisocyanate (HDI). CO was used as both polyol and crosslinker. Butanediol and/or low molecular weight polyethylene glycol (PEG300) were added to the reaction medium as a chain extender. As a magnetic particle, natural magnetite or carbonyl iron was used in various amounts (0–10%). Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscope (SEM), optical microscope, and goniometer were used to characterize all composites and pure PU. A bending test was applied to investigate the shape fixity and shape recovery ratios of the samples. A range of hydrophilic/hydrophobic PU composites (water contact angle is between 56–87°) having various melting and glass transition temperatures were successfully prepared. A PU composite having a good shape recovery ratio (Rr = 96.1%) in a magnetic field was prepared using 10% magnetite. The PU composites were also thermosensitive.

The poor tear resistance of silicone rubber dramatically limits its application range. In this study, a topological entanglement structure of molecular chains was constructed at the interface between the matrix and silica by introducing epoxidized silicone rubber into silicone rubber/silica composites. We found that this topologically entangled structure could improve the crack propagation resistance of the composites by inducing the orientation of molecular chains. The results showed that adding 5 phr of 15% epoxy silicone rubber raised the silicone rubber composite’s tear strength and elongation at break, they increased by 330% and 140, respectively. This work provides a new idea for preparing silicone rubber composites with high tear resistance to better expand the application field of silicone rubber.

In this work, cis-1,4-polybutadiene rubber/polystyrene-butadiene rubber (BR/SBR) blend was filled with inorganic lightweight filler hollow glass microspheres (HGMs) to develop a rubber-based lightweight composite. Cu-plating was carried out on the surface of HGMs by polydopamine (PDA) and Ag nanoparticles to improve the compatibility among HGMs and rubber matrix. Filter paper experiment, X-ray energy dispersive spectroscopy (EDS) and X-ray photoelectron spectrometer (XPS) were used to analyze the bonding mechanism between Cu-plated HGMs and rubber. The results confirmed that the redox reaction between the reactive sulfur in the rubber matrix and Cu on the surface of Cu-plated HGM can be successfully carried out at 170°C. And the compatibility between HGM and rubber matrix was obviously improved after Cu plating. The physical-mechanical properties and abrasion resistance of the composites were improved significantly. This research was of great significance to marine flexible floating body materials.

Hybridization of natural and synthetic fibers in a single composite material can be made by several means, and one of the best methods is the intra-ply in which both fibers are woven within a single layer. Through hybridization, the advantages of one type of fiber can improve the limitations of the other. Further the blending of natural and synthetic fibers leads to the fabrication of composites with higher mechanical performance. Hence, this work focuses on the fabrication of intra-ply Kevlar and hemp fiber reinforced epoxy hybrid composites with different weaving patterns such as plain weave, basket weave, and twill weave type. Yarns were woven by handloom technique to make intra-ply Kevlar and hemp fiber mats, and the composites were fabricated by compression molding. The water absorption, thickness swelling, and solid particle erosion characteristics of the composites were examined. The results of the experiments showed that the hemp fiber composites exhibited the least resistance (8.45% change in absorption and 4.34% change in thickness) towards the absorption and swelling, whereas pure epoxy (0.67% change in absorption and 0.31% change in thickness) and Kevlar (2.67% change in absorption and 1.67% change in thickness) composites possessed higher resistance. The absorption and swelling performance of all other hybrids was found to be in between the hemp and Kevlar composites hence proving the effectiveness of the hybridization. Further, Taguchi’s experimental design results indicated that the basket weave type hybrid composites had a minimal erosion rate for 2 minutes of exposure duration and an impact angle of 90°. The morphological analysis of the eroded surfaces of composites revealed the presence of micro cavities, broken fibers, crater formation, and microcracks.

Organic solar cells (OSCs) fabricated with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films often have limited performance due to high sheet resistances since commercial PEDOT:PSS contains a high insulating PSS to conducting PEDOT ratio. To resolve this issue, zinc iodide (ZnI2) additive was utilized to modify PEDOT:PSS films, which was carried out by mixing ZnI2 with PEDOT:PSS solution. The mixture was deposited on a fluorine-doped tin oxide substrate to derive the modified PEDOT:PSS films for application as a hole-transporting layer in OSCs. This resulted in an enhanced power conversion efficiency for OSCs fabricated with modified PEDOT:PSS films. The enhancement was primarily due to the improved PEDOT:PSS/PCDTBT:PC70BM (poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] – PCDTBT, [6,6]-phenyl-C71-butyric acid methyl ester – PC70BM) interfaces, which facilitates enhanced hole collection performance and results in a high current density for OSC devices. Moreover, the ZnI2 plays a role in the depletion of insulating PSS from the film’s surface. This behavior causes lower sheet resistance and results in an increased Jsc and Voc for OSC devices. Therefore, the improved interfacial contact and depletion of PSS are considered synergistic functions for OSC enhancement.

This work reports on the development of polylactide (PLA)/mango kernel seed flour (MKSF) composites combined with tributyrin (TBN) and triacetin (TCN) as plasticizers. Thus, wood plastic composites (WPC) are obtained by extrusion and injection-molding processes. The solubility, mechanical, morphological, thermal, colorimetric, water absorbance, flowability, and disintegrability properties are evaluated. The ductility of the PLA+MKSF composite is improved by the plasticizing effect of TBN and TCN (10 phr (parts per hundred resin) each). Elongation at break is increased from 4.4 up to 9.5 and 8.3%, respectively. The theoretical solubility analysis supports the good miscibility between PLA with TBN and TCN (relative energy difference (RED) values of 0.86 and 0.73, respectively) deduced from the mechanical performance. Field emission scanning electron microscopy (FESEM) images also corroborate the mechanical findings, where a decrease in the presence of voids in the PLA matrix suggests certain compatibility between MKSF and TBN, and TCN. Differential scanning calorimetry (DSC) and dynamic-mechanical-thermal analysis (DMTA) results show that the plasticizers decrease the glass transition temperature and the melting temperature of PLA, thus improving its ductility. Thermogravimetric analysis (TGA) results indicate that the thermal stability of the composite is slightly decreased due to the relatively high volatility of the plasticizers, while MKSF does not affect this matter. The composites exhibit excellent biodegradability, presenting more than 90% of disintegration in compost soil conditions in 12 weeks. Finally, MKSF provided the composites with a wood-like dark brown color and with high water absorbance.

In this work, hydroxyapatite (HAp) was functionalized by using poly(ethylene glycol) (PEG) with different average molar mass and diisocyanates as linkers and then incorporated into the polyoxymethylene (POM) matrix by means of melt processing methods. The effectiveness of the functionalization process and the chemical structure of the obtained hybrid systems were analyzed using thermogravimetric analysis (TG), elemental analysis, and nuclear magnetic resonance (NMR) methods. In the next stage of research, the calculation of the POM crystallization kinetic parameters in the presence of the hybrid filler were calculated. Microscopic and dynamic mechanical analysis (DMA) tests, as well as 13C and 31P and nuclear magnetic resonance (NMR) analyses were done to show the effect of the HAp-g-PEG hybrid filler on the crystallization kinetics and crystallinity of the POM composites. Transmission electron microscopy (TEM) confirmed the uniform distribution of the HAp-g-PEG hybrid additives. Differential scanning calorimetry (DSC) tests did not show any significant effect on the key processing parameters, i.e. melting point and supercooling, which allowed the processing parameters to be maintained for all samples. The study of crystallization kinetics showed a three-dimensional process of POM crystals’ growth in the form of spherulites. The addition of HAp-g-PEG to POM significantly accelerated the crystallization process.

The aromatic biopolymer lignin, present in lignocellulosic material, can act as an antioxidant and has antimicrobial and UV blocking properties due to the presence of aromatic ring and phenolic hydroxyl groups with aliphatic hydroxyl, carboxyl, methoxy groups. It is produced in huge amounts as a by-product during the delignification process in the paper and pulp industries. Lignin-based polymer composites with advantageous properties can fulfill the growing demand for lightweight polymer composites. Incorporating lignin as reinforcement in polymer composite can make it more environmentally friendly. Among four technical lignin, kraft lignin and lignosulfonate have a unique molecular structure that includes sulfur and can be extracted from black liquor and spent liquor, respectively. Moreover, the negatively charged sulfite groups in lignosulfonate can have an electrostatic attraction to a wide range of positively charged polymers and materials, making it an ideal additive for the adsorbent material. The main intention of this review is to increase the knowledge on the use of cheap and widely available kraft lignin and lignosulfonate as reinforcement in polymer composites and to find the shortcomings to advance further research on the application of technical lignin. The article mainly focuses on advancements in kraft lignin and lignosulfonate polymer composites.

This study aimed to explore the best cross-link agent for preparing natural rubber (NR) composites containing sepiolite as filler. Three types of vulcanizing agents, namely, sulfur, peroxide, and phenolic resin, were employed, and their effects on the thermomechanical and mechanical properties and microstructures were investigated. Compared to other vulcanizing agents, the greatest thermomechanical and mechanical properties improvement was achieved by using phenolic resin as a crosslinker. The highest tensile stress and tensile strength improvement were also achieved from the phenolic resin system. Tensile strength was improved by approximately 78%, nearly twice as much as that in the sulfur system. Such drastic improvement was attributed to the combined effect of homogeneity dispersion and strong adhesion between rubber and filler, as revealed by Fourier-transform infrared spectroscopy, facilitating the strain-induced crystallization process in NR. The phenolic resin was the best vulcanizing agent for preparing NR/sepiolite composites.

The development of biodegradable and biocompatible materials to replace non-biodegradable synthetic polymers has received significant interest in biomedical applications. Amongst all biopolymers, polybutylene succinate (PBS) possesses excellent properties, such as biocompatibility, easy processability, biodegradability, non-toxic, good mechanical and thermal properties, which makes it a suitable candidate to replace non-biodegradable synthetic polymers in biomedical applications. This review provides recent advancements, trends, and challenges for the utilization of polybutylene succinate (PBS) and PBS-based materials for biomedical applications, viz. drug delivery, tissue engineering, and biomedical devices. In addition, the design of medical devices from PBS using 3D and 4D printing is also presented. The market analysis, comparison of virgin PBS and synthetic polymer properties, as well as the end of service life, are summarized briefly. The current status, challenges, and future directions are also discussed.

The strain sensors based on conductive natural rubber (NR) composite, filled with carbon nanotubes (CNT) and conductive carbon black (CCB), are developed due to their superior elasticity and sensitivity. To encourage electron tunneling, ionic pathway for electron moving was achieved by modified deep eutectic solvent (mDES) synthesized in-house. It was found that the incorporation of mDES impacts the curing, mechanical and electrical properties of the composites due to the interconnected CNT/CCB-mDES networks. It is demonstrated that the electrical signal sensation of conductive NR composite was improved by adding mDES, and the inconsistent sensor behavior under cyclic and quasi-static loadings was eliminated. The mDES not only improves the movement of electrons, but it also promotes the crosslinking of NR molecules without adding ZnO. In addition, for analyzing the object motion, the piezoresistive rubber sensors were tested on a soft printing structure through the cyclic motion analysis of a soft tendon-based actuator. The obtained electrical signals showed the smooth signal with noise and un-prediction electrical peaks after the combination of the mDES into the conductive NR composites. This clarifies the flexible movement of the CNT/CCB structure into the NR matrix following the specific designed objects’ motion. The present work indicates the different core novel technologies based on the use of mDES in the conductive composites matching with the acceptable electrical signal for applying as the promising motion sensor materials for soft structures.

Remarkable mechanical reinforcement of chitosan films using graphene is extremely important to greatly widen the practical application of chitosan (CS) in many fields, but there still exist challenges to regulating graphene-CS interactions for both enhanced strength and toughness. In this work, we functionalized graphene oxide (GO) with carboxyl (G-COOH) and amino groups (G-NH2), and investigated the effects of interfacial interactions on the mechanical properties of graphene/CS composite films in detail. We found that the G-NH2/CS composites exhibited the most remarkable reinforcement in both tensile strength and toughness than the GO/CS and G-COOH/CS composites, even different from a theoretical prediction on graphene-CS interactions. Such remarkable reinforcement is mainly attributed to the moderate graphene-CS interaction, uniform dispersion, and high alignment of G-NH2 in CS films.

Smart polymer nanocomposite (SPN) is a major interest in the development of wearable electronics, which requires the conductive matrix to be both flexible and stretchable. Polydimethylsiloxane (PDMS) was chosen in this study as it offers flexibility, thermal stability, relative isotropic, homogeneity, low permittivity, and ease of fabrication. The conductive silver paste filler loadings of 40, 50, 60, and 65 wt% were constructed and measured, which showed high conductivity in the range of 1.59–6.58・106 S/m. A rectangular microstrip patch antenna was fabricated based on stretchable PDMS substrate and silver paste polysiloxane composite at a resonance frequency of 3.5 GHz for fifth-generation (5G) communication. The proposed antenna was designed to attach to the human body and integrate with a wearable device. The polymer wearable antenna will easily stretch and bend following the human body shape and movements, which was investigated to further understand the antenna performance at different stretching and bending conditions. Furthermore, the specific absorption rate (SAR) wearable antenna was analysed for safety purposes.

The present work aims at evaluating the mechanical and anti-corrosion behaviour of epoxy coatings modified by recycled waste tire products. In this study, the epoxy coatings reinforced with ground tire rubber (GTR), devulcanised ground tire rubber (DGTR), pyrolytic carbon black (PCB) and original carbon black (CB) particle contents were prepared and applied to the galvanised steel substrate. Micro-mechanical tests (nanohardness and microscratch) were used to measure the mechanical properties of the coatings. Tribological and corrosive performance of the coatings were evaluated using reciprocating ball-on disc test and salt spray corrosion test (5 wt% NaCl), respectively. The experimental results showed that the recycled waste tire products reinforced composite coatings significantly improved resistance to wear and corrosion inhibition property. In the study, the most remarkable results were the increase in wear resistance by 77.7% in the coating strengthened with DGTR. The highest corrosion resistance was obtained in the epoxy coating reinforced with PCB, no white rust was observed on the coating during the salt spray test (1000 hours), and the lowest blistering degree of the sample after the test was obtained as 8F.

This study investigated variations in strain concentration factors (Kɛ) within the full deformation range of self-reinforced poly(ethylene terephthalate) composites (srPETs) with double-edge semicircular holes (DESH) using digital image correlation (DIC) at different width-to-diameter (W/D) ratios. The value of Kɛ agrees with the theoretical concentration factor (Kt) within the elastic deformation range; then, it increases rapidly to a peak because of plastic deformation. Therefore, the change in Kɛ was divided into different stages based on the spread of the yield extent (beginning from the hole edge). These results will help improve the understanding of the yielding phenomenon of open-hole materials and provide early warnings before final material damage. Kɛ decreased in both the elastic and plastic regions with a decrease in W/D; however, there was an exception when the W/D ratio = 1.5. Therefore, the geometric configuration W/D > 1.5 was recommended for designing secure structural ductile composites. The Kɛ of DESH is lower than that of circular holes (CH) in both the elastic and plastic regions for the hole effect. Thus, composites with DESH should be preferred as an alternative for structural applications.

The 6th element of the periodic table is undoubtedly one of the most incredible aspects of creation. Graphene has a 2-D sheet structure comprised of strong covalent bonds between sp2 hybridized carbon atoms and has attracted much research interest because of its unique physicochemical properties. However, the controlled syntheses of mono-layered and few-layered graphene remain topics of research concern. In the present work, chemically reduced graphene oxide (CRGO) was synthesized by ‘top-down’ using the modified Hummers’ method. CRGO and room-temperature-vulcanized silicone rubber (RTV-SR) were mixed to prepare composites with different CRGO loadings. We found that as little as 2 per hundred parts of rubber [phr] CRGO in RTV-SR transformed the normally rigid RTV-SR into a soft composite with a hardness decrease to 15. Moreover, the compressive modulus falls to 0.6 MPa. However, the dissipation losses decrease at 2 phr CRGO, which is a good property. For tensile mechanical properties, the fracture strain increases to 100% while tensile strength falls sharply to 0.1 MPa. Moreover, the electrical conductivity increases as the amount of CRGO increases. So, composite with soft nature and higher electrical properties are useful for various applications such as soft robotics or soft piezoelectric energy harvesting. In this work, the piezoelectric energy harvesting was performed by monitoring the output voltages generated. Output voltages were stable for RTV-SR but increased with increasing cycle number for RTV-SR/CRGO-based composites. This study provides insights into the use of soft RTV-SR/CRGO composites for soft robotics, actuation, energy harvesting, and vehicle applications.

editorial

In this study eco-friendly cellulose/graphene oxide scaffold has been formulated in the presence of different ratios of ethylenediamine (EDA) as a crosslinker via a lyophilization instrument. Cellulose was extracted from paper wastes and companied with graphene oxide (GO). Chemical structure and surface morphology of the extracted cellulose and cellulose/GO foam were investigated by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and the scanning electron microscope (SEM) techniques. The prepared cellulose/GO foam was used as a gas sensing material, including the sensitivity and response/recovery times toward NH3 vapor. The cellulose/GO cryogel which was prepared with the addition of 1.5 mmol of EDA showed the highest sensitivity at room temperature with the response and recovery times at 490 and 620 s, respectively, compared to the cryogel prepared with 2.25 mmol EDA and the pristine cellulose cryogel.

The dielectric and mechanical properties of a wide range of polydimethylsiloxane-based compositions filled with silica component and cured with various metallosiloxanes have been studied. It is shown that the resulting systems are typical dielectrics. Silica component introduction in combination with the metal-siloxane network formation in the material can significantly increase its dielectric permittivity and conductivity in the frequency range

In this work, the crosslinking reaction of epoxidized natural rubber (50 mol% epoxy, ENR-50) by metal ion namely ferric ion (Fe3+, FeCl3, ferric chloride) was studied. It was found that a direct interaction of the ferric ion with the epoxy group as well as internal polymerization enable the ENR to be efficiently cured. The vulcanizing ENR-FeCl3 compound was then reinforced by carbon nanotubes (CNTs). The FTIR spectra of ENR-FeCl3 compounds without and with CNTs show the absorption peak at the wavenumber 470 cm–1, which represents the –O–Fe–O– linkages from a reaction of FeCl3 and opened oxirane ring products of ENR molecules. Furthermore, the ENR-FeCl3 compounds show a typical marching curing curve with a steady increase in torque as increasing of the testing time; especially the effect is more pronounced in CNTs filled system. Furthermore, an increase in the concentration of CNTs causes increasing in torque difference and enhancement of the mechanical properties (i.e., 100% moduli and tensile strength). The SEM micrograph shows good compatibility between CNTs and the rubber matrix in the ENR-FeCl3 compounds. Also, the electrical conductivities of ENR-FeCl3/CNTs nanocomposite increases with the increase of CNTs loading. It is also observed that the degradation temperature (Td) of ENR-FeCl3/CNTs is shifted toward a higher temperature range with the increase of the CNTs loadings.

Energy and environmental protection are two major problems that are faced by the current generation. Coal has been utilized traditionally as a source of electricity globally. However, more ash is generated from the combustion of coal which is carried by gases and precipitated into fly ash. The main problem with fly ash is that, if it is not properly disposed it may cause pollution(s) in the water and soil, which in turn disturb ecological cycle and have negative impact on the environment. Based on the above statement(s), more efforts have been done to recycle fly ash or its utilization for advanced applications. One of the preferred methods for recycling fly ash, is to incorporate it in polymer matrices in order to improve the strength of polymer matrices for advanced applications. Fly ash has been utilized as a reinforcing filler for various polymer matrices due to its high strength and low cost. This review paper discusses different fabrication methods for fly ash/polymer matrices composites. The effect of particle size, modification, synergy of fly ash with other fillers reinforced polymer matrices on the mechanical properties are discussed. Furthermore, there is an in-depth discussion about the specific applications of fly ash reinforced with different polymer matrices. There is also a discussion based on the fly ash/fiber/polymer hybrid composites in relation to the preparation method and mechanical properties, since hybrid systems are known for better properties than single fillers.

Core-shell thermally expandable microspheres (TEMs) were prepared via Pickering suspension polymerization. Acrylonitrile (AN), methacrylic acid (MAA) and N,N-dimethylacrylamide (DMAA) were used as the comonomers, the 2,2′-azobisisobutyronitrile (AIBN) was used as the initiator and the ethyleneglycol dimethacrylate (EGDMA) was used as the crosslinker. The effects of initiator concentration, cross-linking agent concentration and modified monomer type on the morphology, thermal properties and encapsulation content of TEMs were investigated. The results show that the small change in initiator concentration had a significant effect on the properties of TEMs. When the initiator concentration was 0.55%, the microspheres showed core-shell structure and the maximum expansion ratio was 3.06 times. According to the scanning electron microscope (SEM) image, the heat resistance of the microspheres increased with the increase of the content of crosslinking agent. The lower the water solubility of the modified monomer, the more stable the foaming of the TEMs. When methyl acrylate (MA) was used as a modified monomer, the initial expansion temperature of the microspheres was 163.2°C, the maximum expansion temperature was 223.5 °C, and the encapsulation content of the blowing agent was 14.70%.

Novel materials with neutron shielding property were fabricated by incorporating boron compounds into highdensity polyethylene (HDPE)/Ethylene propylene diene monomer rubber (EPDM) blends. A detailed investigation on the morphological, thermal, mechanical, and neutron attenuation properties of suitable proportion of HDPE/EPDM blend with boric acid (BA), boron carbide (BC), and nano boron carbide (NBC) were performed. Morphology of the 20 wt% of EPDM shows better distribution in HDPE matrix. BA filler is localised in the HDPE phase, while NBC shows uniform distribution in HDPE/EPDM blend compared to its micro counterpart. There is a reduction in the tensile strength and modulus with the incorporation of EPDM in HDPE, whereas the ductility of HDPE is enhanced. A significant increase in the tensile toughness of the HDPE/EPDM blend with lower tensile strength and modulus is observed for BA, and BC filled composites. Moreover, HDPE/EPDM composites with NBC show only a marginal increase in the tensile toughness, tensile strength, and modulus. Comparison of the Young’s modulus of the HDPE/EPDM blends with theoretical models indicates trends similar to the Coran model. The BA and BC filled composites follow the lower bound series model, whereas NBC composites show behaviour similar to the Halpin Tsai model. Total thermal neutron macroscopic cross-section (0.025 MeV energy neutrons) of 10 cm–1 and mean free path of 0.1 cm was obtained for 20 wt% NBC HDPE/EPDM composites.

Passive radiative cooling is a key technology to solve the global warming and energy waste caused by refrigeration. However, because of the high price and complex manufacturing process, the application of daytime radiative cooling materials in the field of building materials is hindered. Here, we studied a low-cost radiative cooling cellulose-based composite material prepared from wood powder that exhibits highly selective infrared emission and high solar reflectivity. And we use the evaporation deposition technique to form a dual-layer structure with silica microspheres in the lower layer. The radiative cooling film based on the intrinsic absorption of lignocellulose and silica microspheres exhibits not only high infrared emissivity of 98.7% in the ‘atmospheric window’ range but also exhibits high reflectivity of 98.44% in the visible light range. We have also found that the performance of the radiative cooling film is the best when the content of silica microspheres reaches 30 wt%, and the film exhibits a cooling of 9.6 °C under direct sunlight. The preparation method of low-cost and high-performance radiative cooling material provided in this article is expected to provide a reference for the application of radiative cooling materials in building materials.

Vinylsilane grafted carbon nanotubes (VCNTs) can act as reactive compatibilizers for cocontinuous poly(lactic acid)/high-density polyethylene (PLA/HDPE) blends, with the aid of organic peroxides initiated radical reactions. The reactively compatibilized PLA/HDPE/VCNTs blend nanocomposites exhibit strong interfacial interactions, as can be reflected by the remarkably increased storage modulus at low frequencies. Due to strong interfacial interactions, the VCNTs act as highly efficient nucleating agents for the PLA component. With 2.0 wt% of VCNTs, the crystallinity of PLA component reaches a value of 33.8% after melt cooling, and thus cold crystallization can no longer be observed upon heating. Thanks to the high crystallinity of the PLA component, the reactively compatibilized blend nanocomposite with 2.0 wt% of VCNTs shows a much higher elastic modulus than those of pristine PLA/HDPE blends and uncompatibilized blend nanocomposites in the temperature range of 60 to 80°C. Moreover, the reactively compatibilized blend nanocomposites exhibit an obvious increase trend in tensile strength with increasing the content of VCNTs, due to stronger interfacial interactions. This work provides a generic strategy for compatibilizing and reinforcing immiscible polymer blend nanocomposites using reactive carbon nanotubes.

A glucose sensor has been developed for daily diagnosis due to high level of glucose can cause diabetes. This study purposes of fabricating an electrospun fiber film of poly(3-aminobenzylamine) (PABA)/functionalized multi-walled carbon nanotubes (f-CNTs) composite for use as electrochemical glucose biosensor. The electrospun PABA/f-CNTs composite film was fabricated on a screen-printed electrode and characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and field emission–scanning electron microscopy (FE-SEM). The presence of f-CNTs in the composite could enhance the electrochemical activities of the PABA, which was confirmed by cyclic voltammetry (CV), amperometry, and electrochemical impedance spectroscopy (EIS). The electrochemical glucose biosensor based on the electrospun PABA/f-CNTs composite film showed a sensitivity of 0.40 μA·mm–2·mM–1 with LOD of 0.067 mM in the linear range of 0.56–2.8 mM, high selectivity under the common interferences (i.e., uric acid, ascorbic acid, and dopamine) and good stability up to 1 week with the current response retained about 80%.

Methacrylic copolymers have high potential as matrix polymers for carbon fiber reinforced thermoplastics (CFRTPs) due to their superior mechanical properties and the versatility of the monomers. However, the methacrylic copolymers have low solvent resistance, compared to epoxy, polyamide, and polypropylene, due to their un-cross-linked amorphous structure. Therefore, an improvement of the solvent resistance by the introduction of metal salts into methacrylic copolymer matrices for CFRTPs was investigated. Infrared spectroscopy, dynamic mechanical analyses and small-angle X-ray scattering clarified that an ionic cross-linked structure was formed. Low-viscosity mixtures of the methacrylic monomers with the metal salts, as a precursor of the matrices for CFRTPs, were easily impregnated into CF fabrics and were then copolymerized within the CF fabrics. Both the flexural strength and shear adhesive strength of the CFRTPs using the in situ polymerized methacrylic ionomer cross-linked with sodium ions were sufficiently high, even after 12 h immersion in methyl ethyl ketone.

With the increasing demand for liquid manipulation and microfluidic techniques, surfaces with external stimuli induced real-time tunable wetting properties are getting into the focus of materials science research. In this study, we present poly(dimethylsiloxane) (PDMS) copolymer-based composite coatings with thermally adjustable wetting and visible-light photoreactivity. To give thermal responsivity to the spray-coated or doctor blade-casted PDMS surfaces, they were grafted with poly(N-isopropylacrylamide) (PNIPAAm), applying the Activators Regenerated by Electron Transfer – Atom Transfer Radical Polymerization (ARGET-ATRP) method. As the lower critical solution temperature (LCST) of the grafted PNIPAAm chains appeared to be 34°C, the copolymer films showed thermoresponsive, and PNIPAAm surface concentration-dependent wetting characteristics. The addition of 15 wt% visible light-active plasmonic Ag-TiO2 photocatalyst nanoparticles (dprimary ~50 nm) enriched the coatings with photocatalytic activity, which was also proven to be temperature-dependent during methylene-blue (MB; c0 = 6.25 mM) photodegradation tests (blue LED-light, λ = 405 nm) at the S/L-interface. Thanks to the real-time tunable wetting and photocatalytic properties, the presented coatings may offer a novel route towards sophisticated liquid manipulation.

Epoxy composites filled by multiwalled carbon nanotubes treated by inductively coupled ammonia plasma were prepared to improve composite intrinsic properties. The ammonia plasma treatment generated amine and oxygenated groups on the carbon nanotube surface, which facilitated its interaction with the epoxy ring and restricted the slippage of epoxy from the carbon nanotube surface. As a result, an improvement in the elastic modulus of the composite by the embedded carbon nanotubes and a decrease in the glass transition temperature and the cure degree were found. It indicated a strengthening effect of the carbon nanotube filler in the epoxy matrix explained by the generation of chemical reaction pathways between treated filler and the epoxy matrix detected by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy during different stages of the composite formation. To demonstrate the use of carbon nanotube-filled epoxy composites, a microstrip resonant vapor sensor was assembled that was used to detect the occurrence of volatile organic compounds and to monitor the ambient temperature below and over the glass transition temperature.

In the past, polymer materials have been used in electronic devices; however, the major drawback with polymers is their low thermal conductivity, i.e., 0.1–0.5 W/(m・K). Hence, researchers came up with the idea of incorporating conductive fillers into the polymer matrix in order to increase their thermal conductivity. Different conductive materials classified as carbon, metallic, and ceramic-based fillers have been used for this task. However, the drawback with carbon and metalbased fillers is that they reduce the intrinsic insulating properties of polymer materials. Recently, boron nitride (BN), a ceramic-based filler was selected as the conductive filler of choice due to its combined excellent thermal conductivity and electrical insulation as well as high breakdown strength. Due to differences in polarities, boron nitride and polymer matrices form a weak interfacial bond. Therefore, the weak interfacial bond is commonly improved by surface chemical modification of the boron nitride fillers. Furthermore, most of the theoretical models are used to predict the thermal conductivities of boron nitride-polymers composites fitted well with experimental data. This proved that the models could be used to predict the properties of boron nitride composites before their experimental data. The review paper discusses the effect of boron nitride orientation, nanostructures, modification, and its synergy with other conductive fillers on the thermal conductivity and mechanical properties of the polymer matrices.

In this paper, toluene-diisocyanate-trimer (TDI-T) was utilized to manufacture a new type of epoxy resin with high toughness via the co-polymerization method. In the procedure of preparing bisphenol A epoxy resin, before the reaction between bisphenol A (BPA) and epichlorohydrin (ECH), TDI-T was introduced to react with BPA for embedding flexible segments into the chain of epoxy resin, and obtaining the prepolymers, which are easy to form spatial interweaving network structures, then modified epoxy resin (TDI-T/EP) was manufactured. Mechanical properties, thermomechanical properties, and corrosion resistance of the cured TDI-T/EP were tested and characterized. Due to flexible segments and partial molecular network structure, the material presents high mechanical properties, especially the toughness, and the results show that the maximum tensile strength of cured TDI-T/EP reaches 30.3 MPa, and the maximum fracture elongation reaches 48.02%, at the same time the compressive strength arrives at 57.5 MPa. Compared with cured E-51, the toughness, strength, and fracture elongation are all strikingly enhanced. At the same time, the cured TDI-T/EP also has an excellent heat resistance and corrosion resistance, which avoided worries at home for its application. This work provides a new method for manufacturing high-toughness epoxy resins.

The present research aims to clarify the friction and wear behavior, the transfer layer formation, and the wear mechanism of mono-filled polytetrafluoroethylene (PTFE). A well-known limitation of PTFE is the low wear resistance, which can be surpassed with the use of micro- or nanoparticles. The applied fillers were graphene, alumina (Al2O3), boehmite alumina (BA80), and hydrotalcite (MG70). The samples were produced by room temperature pressing – free sintering method. All specimens were tested with a pin-on-disc tribo-tester in dry contact condition against 42CrMo4 steel disc counterface with 3 MPa contact pressure and 0.1 mm/s sliding speed. PTFE filled with 4 wt% Al2O3 achieved the highest wear resistance; the increase was more than two orders of magnitude compared to the neat PTFE. This improvement comes from the protective transfer layer formation due to the Al2O3 and the iron-oxide accumulation on the polymer contact surface. Significant wear-induced crystallinity was also registered, which originated from the mechanical chain scission of the PTFE molecular chains during the wear process.

A series of novel shape memory and self-healing composites of natural rubber (NR) and polycyclooctene (PCO) were designed using a simple physical blending method. These two polymers were selected with the intent of introducing network flexibility and mobility into the prepared blends. The mechanical, curing, thermal, shape memory, and thermally assisted self-healing properties of the NR/PCO composites were investigated in this study. In these composites, the crosslinked network generated in both the NR and PCO portions acted as a fixed phase, while the crystalline regions of the PCO portions acted as a reversible phase in the shape memory behavior. The composites showed self-healing properties at an elevated temperature (90 °C), which was attributed to molecular chain interdiffusion processes. Shape memory and thermally assisted self-healing properties were improved by increasing polycyclooctene content. The NR/PCO showed superior mechanical, shape memory, and self-healing properties (Rf = 94.57%, Rr = 98.92% and healing efficiency = 19.03%) when the blending ratio was 50/80. Due to these superior properties, this kind of natural rubber-based composites may have the potential to be used in intelligent and thermal-response shape memory fields.

Carbon fibers (CFs) are commonly applied reinforcement material in various composites to improve their mechanical, thermal, or electrical properties. The physical and chemical state of the interface, the chemical bonds, and adhesion between the fiber and matrix have a great influence on certain properties of the composite, including the mechanical ones. The originally low adhesion between the CFs and the matrix material can be improved by employing non-equilibrium plasma for surface treatment of the fiber. In the present study, we compared the effect of an atmospheric dielectric barrier discharge (DBD) and a low-pressure radio frequency (RF) plasma processing on poly(acrylonitrile) based and sized CFs in terms of surface chemistry, morphology, and adhesive properties of the treated fibers. It was found that atmospheric DBD plasma treatment induced greater changes in the surface properties of the CFs as compared to RF plasma. The DBD treated CF surface became more oxidized, increasing the O/C ratio by 30%, while reaching a twofold increase in the roughness. Surface adhesion improved after both plasma treatments, but it was significantly higher after the atmospheric DBD process.

We explored a simple approach to grow needle-like polyphosphazene nanotubes (PZSNT) on carbon fibers (CFPZSNT) via in-situ polycondensation under mild reaction conditions, to form a PZSNT-based multiscale reinforcement. PZSNT with abundant free hydroxyl groups can significantly change the chemical surface and increase the specific surface area of carbon fibers. A significant improvement of interfacial shear strength was obtained from 39.7 MPa for the virgin CF/polyamide 6 composites to 69.6 MPa for the CF-PZSNT/polyamide 6 composites.

In the present study, a new method for the synthesis of the open-cell soft polyurethane foam (PUF) is developed. Silver nanoparticles are synthesized on the surface of ultrafine grain (100–500 nm) natural zeolite particles and this zeolite is than placed as a filler in the polyurethane. The Ag content of natural zeolite and PUF is about 5 wt%, and 1500 ppm, respectively. Most of the zeolite particles are partially or fully covered in the polyurethane cell wall which is favorable for long-term storage. However, as soon as the foam comes into contact with water or human sweat, the montmorillonite content of the zeolite swells and breaking through the cell wall of the foam structure. Indeed, particles of the zeolite protrude from the polyurethane matrix with the nano-silver particles showing a favourable biocide effect. The antibacterial effect of the natural zeolite containing Ag nanoparticles was examined against Escherichia coli (Gram-negative), and Micrococcus luteus (Gram-positive) strains in a 24 and 72 h interval. The results show that the natural zeolite containing Ag nanoparticles filler has an antibacterial effect, especially against Gram-positive bacteria.

In this study, modified natural rubber (MNR) was used as a solid adsorbent for carbon dioxide (CO2) capture. The chemical structure of the NR latex was modified by diallylamine. Moreover, the silica particles were modified by (3-aminopropyl)trimethoxysilane, N-[(3-trimethoxysilyl)propyl]ethylenediamine, or N-[(3-trimethoxysilyl)propyl]diethylenetriamine (mono-, di- and tri-amines) to improve the CO2 capture ability of the MNR. The CO2 adsorption capacity of the MNR foam composite was increased 3- to 5-fold after filling with unmodified or modified silica particles. The mechanism for CO2 adsorption of the MNR composite was a combination of physisorption and chemisorption. At 100 °C, the highest CO2 adsorption capacity of MNR foam composite (10.35 mg/g of adsorbent) was obtained by adding tri-amine-modified silica particles. Finally, the MNR foam composite material could be regenerated process for more than 20 CO2 adsorption cycles.

This paper presents a novel investigation on the robustness of Acoustic Emission (AE) technique on the characterization of indentation-induced Damage Mechanisms (DMs) in scaled laminated composites. AE is used to monitor a comprehensive series of scaled Quasi-Static Indentation (QSI) tests performed on Quasi-Isotropic (QI) S-glass/8552 epoxy composite plates, with in-plane and intra-plane scaling. A detailed assessment of the damage evolution is carried out through clustering of the monitored AE signals. The AE results indicated the existence of different DMs such as delamination, matrix cracking and fiber breakage. Ultrasonic C-scan and visual observations were also used to verify the AE based results. It was observed that both in-plane and intra-plane scaling alter the induced DMs, and the AE analysis was able to accurately identify and quantify the DMs in each case. However, the AE features (frequency, energy and count) were found to be dependent on different variables such as size, geometry and stacking sequence of the investigated samples. This research highlights the potential and challenges to develop AE as a reliable structural health monitoring system for impact/indentation damage monitoring of composite plates over a range of sizes and complexities.