Polymers, Volume 11, Issue 1 (January 2019) – 186 articles

This paper designed and manufactured photosensitive resin-based 2-D lattice structures with different types of variable cross-section cores by stereolithography 3D printing technology (SLA 3DP). An analytical model was employed to predict the structural compressive response and failure types. A theoretical calculation was performed to obtain the most efficient material utilization of the 2-D lattice core. A flatwise compressive experiment was performed to verify the theoretical conclusions. A comparison of theoretical and experimental results showed good agreement for structural compressive response. Results from the analytical model and experiments showed that when the 2-D lattice core was designed so that R/r = 1.167 (R and r represent the core radius at the ends and in the middle), the material utilization of the 2-D lattice core improved by 13.227%, 19.068%, and 22.143% when n = 1, n = 2, and n = 3 (n represents the highest power of the core cross-section function). Full article

In this work, a side-by-side bicomponent thermoplastic polyurethane/polyimide (TPU/PI) polymer electrolyte prepared with side-by-side electrospinning method is reported for the first time. Symmetrical TPU and PI co-occur on one fiber, and are connected by an interface transition layer formed by the interdiffusion of two solutions. This structure of the as-prepared TPU/PI polymer electrolyte can integrate the advantages of high thermal stable PI and good mechanical strength TPU, and mechanical strength is further increased by those isotropic interface transition layers. Moreover, benefiting from micro-nano pores and the high porosity of the structure, TPU/PI polymer electrolyte presents high electrolyte uptake (665%) and excellent ionic conductivity (5.06 mS·cm⁻¹) at room temperature. Compared with PE separator, TPU/PI polymer electrolyte exhibited better electrochemical stability, and using it as the electrolyte and separator, the assembled Li/LiMn₂O₄ cell exhibits low inner resistance, stable cyclic and notably high rate performance. Our study indicates that the TPU/PI membrane is a promising polymer electrolyte for high safety lithium-ion batteries. Full article

A polyaniline (PANI)/tin oxide (SnO₂) composite for a CO sensor was fabricated using a composite film composed of SnO₂ nanoparticles and PANI deposition in the present study. Tin oxide nanoparticles were synthesized by the sol-gel method. The SnO₂ nanoparticles provided a high surface area to significantly enhance the response to the change in CO concentration at low operating temperature (<75 °C). The excellent sensor response was mainly attributed to the relatively good properties of PANI in the redox reaction during sensing, which produced a great resistance difference between the air and CO gas at low operating temperature. Therefore, the combination of n-type SnO₂ nanoparticles with a high surface area and a thick film of conductive PANI is an effective strategy to design a high-performance CO gas sensor. Full article

The titration behavior of weak polyelectrolytes is of high importance, due to their uses in new technologies including nanofiltration and drug delivery applications. A comprehensive picture of polyelectrolyte titration under relevant conditions is currently lacking, due to the complexity of systems involved in the process. One must contend with the inherent structural and solvation properties of the polymer, the presence of counterions, and local chemical equilibria enforced by background salt concentration and solution acidity. Moreover, for these cases, the systems of interest have locally high concentrations of monomers, induced by polymer connectivity or confinement, and thus deviate from ideal titration behavior. This work furthers knowledge in this limit utilizing hybrid Monte Carlo–Molecular Dynamics simulations to investigate the influence of salt concentration, ${\mathrm{pK}}_{\mathrm{a}}$ , pH, and counterion valence in determining the coil-to-globule transition of poorly solvated weak polyelectrolytes. We characterize this transition at a range of experimentally relevant salt concentrations and explicitly examine the role multivalent salts play in determining polyelectrolyte ionization behavior and conformations. These simulations serve as an essential starting point in understanding the complexation between weak polyelectrolytes and ion rejection of self-assembled copolymer membranes. Full article

The development of visible-light-driven polymeric g-C₃N₄ is in response to an emerging demand for the photocatalytic dye degradation and reduction of hexavalent chromium ions. We report the synthesis of g-C₃N₄ from urea treated with various solvents such as methanol, ethanol, and ethylene glycol. The samples were characterized and the Williamson–Hall method was applied to investigate the lattice strain of the samples. The activity of the samples was evaluated by observing the degradation of methyl orange and K₂Cr₂O₇ solution under light irradiation. Photocatalytic reaction kinetics were determined as pseudo-first-order and zero-order for the degradation of methyl orange and reduction of hexavalent chromium, respectively. Due to the inhibited charge separation resulting from the small lattice strain, reduced crystal imperfection, and sheet-like structure, g-C₃N₄ obtained from ethanol-treated urea exhibited the highest activity among the evaluated samples. Full article

To selectively reduce the yield of hydrogen cyanide (HCN) in the cigarette smoke, functional porous carboxymethyl cellulose/cellulose acetate (CMC/CA) composite microspheres were prepared via the double emulsion-solvent evaporation method. Cupric ions, which have a high complexing ability toward HCN, were introduced to the CMC/CA composite microspheres during the fabrication process via an in situ ion cross-link method. The microspheres were characterized using nitrogen adsorption, mercury intrusion porosimetry, and scanning electron microscopy (SEM). The microspheres have a predominantly macroporous structure indicating weak physisorption properties, but sufficient functional cupric ion groups to selectively adsorb HCN. With these CMC/CA microspheres as filter additives, the smoke yield of HCN could be reduced up to 50%, indicating the great potential of these microspheres as absorbents for removing HCN from cigarette smoke. Full article

In this study, two different types of industrial lignin (i.e., lignosulphonate lignin (LL) and kraft lignin (DL)) were exploited as charring agents with phosphorus-based flame retardants for polyamide 11 (PA11). The effect of lignins on the thermal stability and fire behavior of PA11 combined with phosphinate additives (namely, aluminum phosphinate (AlP) and zinc phosphinate (ZnP)) has been studied by thermogravimetric analysis (TGA), UL 94 vertical flame spread, and cone calorimetry tests. Various blends of flame retarded PA11 were prepared by melt process using a twin-screw extruder. Thermogravimetric analyses showed that the LL containing ternary blends are able to provide higher thermal stability, as well as a developed char residue. The decomposition of the phosphinates led to the formation of phosphate compounds in the condensed phase, which promotes the formation of a stable char. Flammability tests showed that LL/ZnP ternary blends were able to achieve self-extinction and V-1 classification; the other formulations showed a strong melt dripping and higher burning. In addition to this, cone calorimetry results showed that the most enhanced behavior was found when 10 wt % of LL and AlP were combined, which strongly reduced PHRR (−74%) and THR (−22%), due to the interaction between LL and AlP, which not only promotes char formation but also confers the stability to char in the condensed phase. Full article

Poly(3,4-ethylenedi-oxythiophene) (PEDOT) derivatives conducting polymers are known for their great electrochromic (EC) properties offering a reversible blue switch under an applied voltage. Characterizations of symmetrical EC devices, built on combinations of PEDOT thin films, deposited with a bar coater from commercial inks, and separated by a lithium-based ionic membrane, show highest performance for 800 nm thickness. Tuning of the color is further achieved by mixing the PEDOT film with oxides. Taking, in particular, the example of optically inactive iron oxide Fe₂O₃, a dark blue to reddish switch, of which intensity depends on the oxide content, is reported. Careful evaluation of the chromaticity parameters L*, a*, and b*, with oxidizing/reducing potentials, evidences a possible monitoring of the bluish tint. Full article

For the development of light, flexible, and wearable electronic devices, it is crucial to develop energy storage components combining high capacity and flexibility. Herein, an all-solid-state supercapacitor is prepared through an in situ growth method. The electrode contains polyaniline deposited on a carbon nanotube and a poly (ethylene-co-vinyl acetate) film. The hybrid electrode exhibits excellent mechanical and electrochemical performance. The optimized few-layer polyaniline wrapping layer provides a conductive network that effectively enhances the cycling stability, as 66.4% of the starting capacitance is maintained after 3000 charge/discharge cycles. Furthermore, the polyaniline (PANI)-50 displays the highest areal energy density of 83.6 mWh·cm⁻², with an areal power density of 1000 mW·cm⁻², and a high areal capacity of 620 mF cm⁻². The assembled device delivers a high areal capacity (192.3 mF·cm⁻²) at the current density of 0.1 mA·cm⁻², a high areal energy (26.7 mWh·cm⁻²) at the power density of 100 mW·cm⁻², and shows no significant decrease in the performance with a bending angle of 180°. This unique flexible supercapacitor thus exhibits great potential for wearable electronics. Full article

In this study, chitosan nanoparticles were used as a carrier for Protocatechuic acid (PCA) to resist Pyricularia oryzae against rice blast. The final compound was characterized using zeta potentials for its surface electricity, Fourier transform infrared (FT-IR) analysis and transmission electron microscopy (TEM) were conducted for functional groups and for particle sizes and shape, respectively. The zeta potential results showed that loading PCA causes chitosan nanoparticle (CSNP) to decrease in surface electrons. The TEM images revealed that the particle size of chitosan (CS), although increasing in size when carrying PCA molecules, showed sufficient size for reasonable penetration into fungal cells. The FT-IR analysis showed that all functional group in CSNP carried PCA matched with previous studies. The antifungal test showed that diameters of inhibition zone of CS increases significantly after loading PCA, exhibiting the strongest antimicrobial effect on the Pyricularia oryzae fungus compared with weaker effects exhibited by CSNP alone or PCA. Our results suggested that CSNP loaded with PCA could be a potential compound for eradication of Pyricularia oryzae and that further testing on in vitro rice plants is recommended to reaffirm this possibility. Full article

Aromatic voltage stabilizers can improve the dielectric properties of cross-linked polyethylene (XLPE); however, their poor compatibility with XLPE hinders their practical application. Improving the compatibility of aromatic voltage stabilizers with XLPE has, therefore, become a new research goal. Herein 1-(4-vinyloxy)phenylethenone (VPE) was prepared and characterized. It can be grafted onto polyethylene molecules during the cross-linking processes to promote stability of the aromatic voltage stabilizers in XLPE. Fourier transform infrared spectroscopy confirmed that VPE was successfully grafted onto XLPE, and effectively inhibited thermal migration. Thermogravimetric analysis showed that the grafted VPE/XLPE composite exhibits a better thermal stability than a VPE/PE blend composite. Evaluation of the electrical properties showed that the breakdown strength and electrical tree initiation voltage of the VPE/XLPE composite were increased by 15.5% and 39.6%, respectively, when compared to those of bare XLPE. After thermal aging, the breakdown strength and electrical tree initiation voltage of the VPE/XLPE composite were increased by 9.4% and 25.8%, respectively, in comparison to those of bare XLPE, which indicates that the grafted voltage stabilizer can effectively inhibit its migration and enhance the stability of the composite material. Full article

The thermoplastic vulcanizates (TPVs) of polypropylene (PP)/silicone rubber (SR) were prepared by dynamic vulcanization (DV) technology. The mixing torque, morphology, viscoelasticity, and creep response of PP/SR TPVs were investigated by torque rheometer, scanning electron microscope (SEM), transmission electron microscope (TEM), rotational rheometer, and dynamic mechanical analysis (DMA). A mixing-torque study showed that torque change and dynamic-vulcanization time increased with SR content increasing in the DV process, but DV rate was independent of SR content. TEM images indicated that the phase inversion of PP/SR-60 TPV from bicontinuous to a sea–island structure took place in the DV process, and a hot press would break the rubber aggregates and shrink a large SR phase. Dynamic-strain measurement demonstrated that PP/SR TPVs exhibit a distinct “Payne effect”, which can be attributed to the destruction and reconstruction of SR physical networks. Complex viscosity indicated that SR content did not affect the processability of PP/SR TPVs at high shear rates. Furthermore, the creep deformation and recovery of PP/SR TPVs at solid and melt states were studied, respectively. Full article

Modification with Arg-Gly-Asp (RGD) peptides is a promising approach to improve biocompatibility of small-calibre vascular grafts but it is unknown how different RGD sequence composition impacts graft performance. Here we manufactured 1.5 mm poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ε-caprolactone) grafts modified by distinct linear or cyclic RGD peptides immobilized by short or long amine linker arms. Modified vascular prostheses were tested in vitro to assess their mechanical properties, hemocompatibility, thrombogenicity and endothelialisation. We also implanted these grafts into rat abdominal aortas with the following histological examination at 1 and 3 months to evaluate their primary patency, cellular composition and detect possible calcification. Our results demonstrated that all modes of RGD modification reduce ultimate tensile strength of the grafts. Modification of prostheses does not cause haemolysis upon the contact with modified grafts, yet all the RGD-treated grafts display a tendency to promote platelet aggregation in comparison with unmodified counterparts. In vivo findings identify that cyclic Arg-Gly-Asp-Phe-Lys peptide in combination with trioxa-1,13-tridecanediamine linker group substantially improve graft biocompatibility. To conclude, here we for the first time compared synthetic small-diameter vascular prostheses with different modes of RGD modification. We suggest our graft modification regimen as enhancing graft performance and thus recommend it for future use in tissue engineering. Full article

Glycoproteins represent a group of important biomarkers for cancer and other life-threatening diseases. Selective detection of specific glycoproteins is an important step for early diagnosis. Traditional glycoprotein assays are mostly based on lectins, antibodies, and enzymes, biochemical reagents that are costly and require special cold chain storage and distribution. To address the shortcomings of the existing glycoprotein assays, we propose a new approach using protein-imprinted nanoparticles to replace the traditional lectins and antibodies. Protein-imprinted binding sites were created on the surface of silica nanoparticles by copolymerization of dopamine and aminophenylboronic acid. The imprinted nanoparticles were systematically characterized by dynamic light scattering, scanning and transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and elemental analysis. A boronic acid-modified fluorescent probe was used to detect the target glycoprotein captured by the imprinted nanoparticles. Using horseradish peroxidase as a model glycoprotein, we demonstrated that the proposed method can be applied to detect target protein containing multiple glycosylation sites. Because of their outstanding stability and low cost, imprinted nanoparticles and synthetic probes are attractive replacements of traditional biochemical reagents to develop simpler, faster, and more cost-effective analytical methods for glycoproteins. Full article

Animals living in extremely cold plateau areas have shown amazing ability to maintain their bodies warmth, a benefit of their hair’s unique structures and crimps. Investigation of hair crimps using a water-stimulated shape fixation effect would control the hair’s crimpness with a specific wetting-drying process thereafter, in order to achieve the regulation of hair thermal insulation. The mechanism of hair’s temporary shape fixation was revealed through FTIR and XRD characterizations for switching on and off the hydrogen bonds between macromolecules via penetration into and removal of aqueous molecules. The thermal insulation of hairs was regulated by managing the hair temporary crimps, that is, through managing the multiple reflectance of infrared light by hair hierarchical crimps from hair root to head. Full article

Polyvinyl alcohol (PVA) hydrogel and stem cell therapy have been widely used in wound healing. However, the lack of bioactivity for PVA and security of stem therapy limited their application. In this study, an adipose-derived stem cells (ADSCs)-seeded PVA dressing (ADSCs/PVA) was prepared for wound healing. One side of the PVA dressing was modified with photo-reactive gelatin (Az-Gel) via ultraviolet (UV) irradiation (Az-Gel@PVA), and thus ADSCs could adhere, proliferate on the PVA dressings and keep the other side of the dressings without adhering to the wound. The structure and mechanics of Az-Gel@PVA were determined by scanning electron microscopy (SEM) and material testing instruments. Then, the adhesion and proliferation of ADSCs were observed via cell counts and live-dead staining. Finally, in vitro and in vivo experiments were utilized to confirm the effect of ADSCs/PVA dressing for wound healing. The results showed that Az-Gel was immobilized on the PVA and showed little effect on the mechanical properties of PVA hydrogels. The surface-modified PVA could facilitate ADSCs adhesion and proliferation. Protein released tests indicated that the bioactive factors secreted from ADSCs could penetrated to the wound. Finally, in vitro and in vivo experiments both suggested the ADSCs/PVA could promote the wound healing via secreting bioactive factors from ADSCs. It was speculated that the ADSCs/PVA dressing could not only promote the wound healing, but also provide a new way for the safe application of stem cells, which would be of great potential for skin tissue engineering. Full article

The damage and fracture of fiber reinforced polymer composites are vital constraints in their applications. To understand the mechanism of damage of wood fiber (WF) reinforced high density polyethylene (HDPE) composites, we used waste WF and recycled HDPE (Re-HDPE) as the raw materials and prepared high-filled WF/Re-HDPE composites via extrusion. The damage and fracture mode and failure mechanism of the composites with different WF contents (50%, 60%, and 70%) was studied under a three-point bending test by combining the acoustic emission (AE) technique and scanning electron microscope (SEM) analysis. The results show that AE technology can better assist in understanding the progress of damage and fracture process of WF/Re-HDPE composites, and determine the damage degree, damage accumulation, and damage mode. The damage and fracture process of the composites presents three main stages: the appearance of initial damage, damage accumulation, and destructive damage to fracture. The matrix deformation, fiber breakage, interface delamination, fiber-matrix debonding, fiber pull-out, and matrix cracking were the dominant modes for the damage of high-filled WF/Re-HDPE composites under bending load, and the AE signal changed in different damage stages and damage modes. In addition, the WF content and repeated loading had a significant influence on the composite’s damage and fracture. The 50% and 60% WF/Re-HDPE composites produced irreversible damage when repeated load exceeded 75% of the maximum load, while 25% of the maximum load could cause irreversible damage for 70% WF/Re-HDPE composites. The damage was accumulated owing to repeated loading and the mechanical properties of the composites were seriously affected. Full article

Two different azosulphonate dyes were synthesised and purified for the preparation of a water-based photoreactive azosulphonate-doped poly(vinyl alcohol). The aim was the investigation of a novel azosulphonate-poly(vinyl alcohol) photoresist with decreased water solubility after illumination, setting a focus on environmentally benign substances. The electron distribution of the aromatic rings of the two different azosulphonate molecules were changed by the UV-induced cleavage of the –N=N–SO₃⁻ groups, which was evidenced by UV spectroscopy. The formation of ester groups was detected by Fourier-transform infrared and ¹³C nuclear magnetic resonance spectroscopy. UV–Vis spectroscopy was used to investigate the photoreactivity of the prepared films. Photolithographic experiments demonstrated the applicability of these newly produced materials as photoresist materials. In addition, these materials provide high thermal stability. Full article

Three types of expandable graphite (EG) differing in particle size and expansion volume, are compared as flame retardant additives to rigid polyurethane foams (RPUFs). In this paper we discuss microstructure, thermal stability, fire behavior, and compression performance. We find that ell size distributions were less homogeneous and cell size was reduced. Furthermore, thermal conductivity increased along with EG loading. Thermogravimetric analysis (TGA) showed that EG only increased residue yield differently. The results indicate that a higher expansion of EG increased the limiting oxygen index (LOI) value, whereas a bigger particle size EG improved the rating of the vertical burning test (UL94). Results from the cone calorimeter test showed that a bigger particle size EG effectively reduced peak of heat release rate (pHRR). Furthermore, a higher expansion, led to a decrease in smoke production (TSP). The combination of both characteristics gives extraordinary results. The physical–mechanical characterization of the EG/RPUF foams revealed that their compression performance decreased slightly, mostly due to the effect of a bigger size EG. Full article

Thermoelectric devices have recently attracted considerable interest owing to their unique ability of converting heat to electrical energy in an environmentally efficient manner. These devices are promising as alternative power generators for harvesting electrical energy compared to conventional batteries. Inorganic crystalline semiconductors have dominated the thermoelectric material fields; however, their application has been restricted by their intrinsic high toxicity, fragility, and high cost. In contrast, organic thermoelectric materials with low cost, low thermal conductivity, easy processing, and good flexibility are more suitable for fabricating thermoelectric devices. In this review, we briefly introduce the parameters affecting the thermoelectric performance and summarize the most recently developed carbon-material-based organic thermoelectric composites along with their preparation technologies, thermoelectric performance, and future applications. In addition, the p- and n-type carbon nanotube conversion and existing challenges are discussed. This review can help researchers in elucidating the recent studies on carbon-based organic thermoelectric materials, thus inspiring them to develop more efficient thermoelectric devices. Full article

Environmentally benign and biodegradable chitosan (CS) membranes have disadvantages such as low mechanical strength, high brittleness, poor heat resistance and poor water resistance, which limit their applications. In this paper, home-made cellulose nanocrystals (CNC) were added to CS to prepare CNC/CS composite membranes through mechanical mixing and solution casting approaches. The effects of CNC dispersion patterns and CNC contents on the properties of composite membranes were studied. The analysis of the surface and cross-section morphology of the membranes showed that the dispersion performance of the composite membrane was better in the case that CNC was dissolved in an acetic acid solution and then mixed with chitosan by a homogenizer (Method 2). CNC had a great length-diameter ratio and CNC intensely interacted with CS. The mechanical properties of the composite membrane prepared with Method 2 were better. With a CNC content of 3%, the tensile strength of the composite membrane reached 43.0 MPa, 13.2% higher than that of the CNC-free membrane. The elongation at break was 41.6%, 56.4% higher than that of the CNC-free membrane. Thermogravimetric, contact angle and swelling analysis results showed that the addition of CNC could improve the heat and water resistance of the chitosan membrane. Full article

Electroactive organic dyes incorporated in layer-by-layer (LbL) assemblies are of great interest for a variety of applications. In this paper, Alizarin Red S (ARS), an electroactive anthraquinone dye, is employed to construct LbL (BPEI/ARS)_n films with branched poly(ethylene imine) (BPEI) as the complementary polymer. Unconventional LbL methods, including co-adsorption of ARS and poly(4-styrene sulfonate) (PSS) with BPEI to assemble (BPEI/(ARS+PSS))_n, as well as pre-complexation of ARS with BPEI and further assembly with PSS to fabricate ((BPEI+ARS)/PSS)_n, are designed for investigation and comparison. Film growth patterns, UV–Vis spectra and surface morphology of the three types of LbL assemblies are measured and compared to reveal the formation mechanism of the LbL films. Electrochemical properties including cyclic voltammetry and spectroelectrochemistry of (BPEI/ARS)₁₂₀, (BPEI/(ARS+PSS))₁₂₀ and ((BPEI+ARS)/PSS)₁₂₀ films are studied, and the results show a slight color change due to the redox reaction of ARS. ((BPEI+ARS)/PSS)₁₂₀ shows the best stability among the three samples. It is concluded that the manner of dye- incorporation has a great effect on the electrochemical properties of the resultant films. Full article

In this study the effects of increased graphene nanosheet (GNS) concentration on variations in the structure and properties of electrospun GNS-filled poly(trimethylene terephthalate) (PTT/GNS) composite fiber, such as its morphologies, crystallization behavior, mechanical properties, and electrical conductivity, were investigated. The effects of GNS addition on solution rheology and conductivity were also investigated. GNSs were embedded in the fibers and formed protrusions. The PTT cold crystallization rate of PTT/GNS composite fibers increased with the gradual addition of GNSs. A PTT mesomorphic phase was formed during electrospinning, and GNSs could induce the PTT mesomorphic phase significantly during PTT/GNS composite fiber electrospinning. The PTT/GNS composite fiber mats (CFMs) became ductile with the addition of GNSs. The elastic recoveries of the PTT/GNS CFMs with 170 °C annealing were better than those of the as-spun PTT/GNS CFMs. Percolation scaling laws were applied to the magnitude of conductivity to reveal the percolation network of electrospun PTT/GNS CFMs. The electrical conductivity mechanism of the PTT/GNS CFMs differed from that of the PTT/GNS composite films. Results showed that the porous structure of the PTT CFMs influenced the performance of the mats in terms of electrical conductivity. Full article

In this study, we investigate structures and stabilities of the micelles of a cyclic amphiphile (c-PBA-b-PEO) composed of poly(n-butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) blocks and its linear diblock and triblock analogues (l-PBA-b-PEO and l-PBA-b-PEO-b-PBA) by using synchrotron X-ray scattering and quantitative data analysis. The comprehensive scattering analysis gives details and insights to the micellar architecture through structural parameters. Furthermore, this analysis provides direct clues for structural stabilities in micelles, which can be used as a good guideline to design highly stable micelles. Interestingly, in water, all topological polymers are found to form ellipsoidal micelles rather than spherical micelles; more interestingly, the cyclic polymer and its linear triblock analog make oblate-ellipsoidal micelles while the linear diblock analog makes a prolate-ellipsoidal micelle. The analysis results collectively inform that the cyclic topology enables more compact micelle formation as well as provides a positive impact on the micellar structural integrity. Full article

The thermal and electrical properties of a polymer nanocomposite are highly dependent on the dispersion of the CNT filler in the polymer matrix. Non-covalent functionalisation with a PVP polymer is an excellent driving force towards an effective dispersion of MWNTs in the polymer matrix. It is shown that the PVP molecular weight plays a key role in the non-covalent functionalisation of MWNT and its effect on the thermal and electrical properties of the polymer nanocomposite is reported herein. The dispersion and crystallisation behaviour of the composite are also evaluated by a combination of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Full article

In this study, the actual anti-biofouling (AF) efficacy of three protective coatings, including a chlorinated rubber-based coating (C₀) and two polydimethylsiloxane (PDMS)-based coatings (P₀ and P_F), were estimated via the static field exposure assays. The surface properties of these protective coatings, including surface wettability and morphology features, were characterized using the static water contact angle (WCA) and scanning electron microscope (SEM). The colonization and succession dynamics of the early-adherent biofilm-forming eukaryotic microbial communities occupied on these protective coatings were explored using the Single-stranded Conformation Polymorphism (SSCP) technique. The field data clearly revealed that coating P₀ and P_F performed better in the long-term static submergence, as compared with the C₀ surface, while coating P_F showed excellent AF efficacy in the field. Fingerprinting analysis suggested that the diversity, abundance, the clustering patterns, and colonization dynamics of the early-colonized eukaryotic microbes were significantly perturbed by these protective coatings, particularly by the P_F surfaces. These differential AF efficacy and perturbation effects would be largely ascribed to the differences in the wettability and surface nanostructures between the C₀, P₀ and P_F surfaces, as evidenced by WCA and SEM analysis. Full article

Composite structures are particularly vulnerable to impact, which drastically reduces their residual strength, in particular, at high temperatures. The glass-transition temperature (T_g) of a polymer is a critical factor that can modify the mechanical properties of the material, affecting its density, hardness and rigidity. In this work, the influence of thermal ageing on the low-velocity impact resistance and tolerance of composites is investigated by means of compression after impact (CAI) tests. Carbon-fibre-reinforced polymer (CFRP) laminates with a T_g of 195 °C were manufactured and subjected to thermal ageing treatments at 190 and 210 °C for 10 and 20 days. Drop-weight impact tests were carried out to determine the impact response of the different composite laminates. Compression after impact tests were performed in a non-standard CAI device in order to obtain the compression residual strength. Ultrasonic C-scanning of impacted samples were examined to assess the failure mechanisms of the different configurations as a function of temperature. It was observed that damage tolerance decreases as temperature increases. Nevertheless, a post-curing process was found at temperatures below the T_g that enhances the adhesion between matrix and fibres and improves the impact resistance. Finally, the results obtained demonstrate that temperature can cause significant changes to the impact behaviour of composites and must be taken to account when designing for structural applications. Full article

Crude water-extracted pectin (WEP) isolated from creeping fig seeds were mainly fractionated into WEP-0.3 and WEP-0.4 fractions. Fractions were confirmed to be nonstarch, nonreducing sugars, nonpolyphenols and protein-unbounded acidic polysaccharides. Interestingly, a significant difference in solubility was found between WEP-0.3 (higher solubility than WEP) and WEP-0.4 (remarkably insoluble), which was consistent with the amorphous and porous sponge-like structure of WEP-0.3 as well as the crystalline and dense rod-like state of WEP-0.4. However, the result of the FT-IR spectra was contradicted by the solubility of WEP-0.4, which possessed the lowest degree of methoxylation and ought to possess the highest solubility. Through mineral analysis, a considerably high content of Ca²⁺ was found in WEP-0.4, suggesting that the low solubility of WEP-0.4 was probably attributable to the formation of microgels during dialysis. Therefore, metal divalent cations in the dialysate were suggested to be depleted for the dialysis of low methoxyl pectin. Full article

In this study, an organic–inorganic (O–I) nanohybrid obtained by incorporating an alkoxysilane-functionalized amphiphilic polymer precursor into a SiO₂–TiO₂ hybrid network was successfully utilized as a buffer layer to fabricate a flexible, transparent, and stable conductive substrate for solution-processed silver nanowires (AgNWs) and graphene under ambient conditions. The resulting O–I nanohybrid sol (denoted as AGPTi) provided a transmittance of the spin-coated AgNWs on an AGPTi-coated glass of 99.4% and high adhesion strength after a 3M tape test, with no visible changes in the AgNWs. In addition, AGPTi acted as a highly functional buffer layer, absorbing the applied pressure between the conductive materials, AgNWs and graphene, and rigid substrate, leading to a significant reduction in sheet resistance. Furthermore, gravure-printed AgNWs and graphene on the AGPTi-based flexible substrate had uniform line widths of 490 ± 15 and 470 ± 12 µm, with 1000-cycle bending durabilities, respectively. Full article

A series of propylene-co-styrenic monomer copolymers were synthesized using the Friedel–Crafts alkylation reaction between chlorinated PP and substituted benzene, and the effects of these copolymers on a PP/PS (80/20) blend were investigated by using the impact test, morphology observation, thermo- and dynamic mechanical analysis, and rheology measurements. The results showed that the compatibilization efficiency varied as the variation of the substitute on the benzene ring of the styrenic monomer unit was incorporated in the PP chain in an order of methyl > ethyl > methoxyl. The copolymers bearing a crystalline isotactic polypropylene chain sequence and rubbery propylene-co-styrene-like unit chain segments may prepossess imaginable applications, giving an example for the synthesis and applications of PP-based copolymers, initiating a new way to broaden the polyolefin-based material family. Full article