Properties of starch–cellulose fiber films produced by tape casting coupled with infrared radiation

Tape casting is a suitable process for large-scale production of biodegradable films. This study presents a comparison of three drying procedures of starch–cellulose films: i) conduction drying, ii) infrared drying (42.3?W?m^?2, higher infrared heating power damaged the films), and iii) conduction-infrared drying. All the drying procedures were performed at approximately 60°C. Drying times from the second and third methods were close to 1?h, half the time observed for conduction drying. Films from the second and third methods showed similar hygroscopicity (0.15?g.?g^?1, RH 43%), tensile strength (31.3?MPa, RH 58%), and glass transition temperature (?12.13°C, RH 43%).     

Preparation and characterization of electrospun polyurethane–polypyrrole nanofibers and films

Polyurethane (PU)–polypyrrole (PPy) composite films and nanofibers were successfully prepared for the purpose of combining the properties of PU and PPy. Pyrrole (Py) monomer was polymerized and dispersed uniformly throughout the PU matrix by means of oxidative polymerization with cerium(IV) [ceric ammonium nitrate Ce(IV)] in dimethylformamide. Films and nanofibers were prepared with this solution. The effects of the PPy content on the thermal, mechanical, dielectric, and morphological properties of the composites were investigated with differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR)–attenuated total reflection (ATR) spectroscopy, dielectric spectrometry, and scanning electron microscopy. The Young's modulus and glass-transition temperatures of the composites exhibited an increasing trend with increases in the initially added amount of Py. The electrical conductivities of the composite films and nanofibers increased. The crystallinity of the composites were followed with DSC, the mechanical properties were followed with DMA, and the spectroscopic results were followed with FTIR–ATR spectroscopy. In the composite films, a new absorption band located at about 1650 cm⁻¹ appeared, and its intensity improved with the addition of Py. The studied composites show potential for promising applications in advanced electronic devices. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Folic acid–egg white coated IPN network of carboxymethyl cellulose and egg white nanoparticles for treating breast cancer

Recurrent cancer treatments fail to distinguish between the normal cells and cancer cells and lead to severe systemic toxicity and side effects. The current researchers focus to overcome these conventional pharmacological barriers by increasing the selectivity of cancer cell by targeting mechanism. In this study, interpenetrating polymeric network (IPN) of carboxymethyl cellulose (CMC) and egg white (EW), cross-linked with polyethylene glycol (PEG), and polyvinyl alcohol (PVA) loaded with cyclophosphamide (CP) were synthesized by heat coagulation method and coated with folic acid–egg white (FA–EW) conjugate. The prepared IPN–NPs were characterized using FTIR, P-XRD, and FE-SEM. Particle size, polydispersity index and zeta potential were also evaluated. FA–EW/CP [IPN–NPs] shows high entrapment efficiency of 94?±?1.52%. The release analysis of CP from FA–EW/CP [IPN–NPs] showed a pH-responsive behavior with a rapid release at pH 5.0 and 6.0 rather than pH 7.4. Hemocompatibility of drug delivery systems is proved by hemolysis assay. The confocal microscope studies specify the possible uptake of FA–EW/CP [IPN–NPs] in MCF-7 breast cancer cell lines. The cytotoxicity analysis of MCF-7 cells by fluorescent live/dead cell assay and MTT assay suggest that FA–EW/CP [IPN–NPs] exhibit higher cytotoxicity compared to free CP and IPN–NPs. The obtained FA–EW/CP [IPN–NPs] might serve as a potential candidate for targeted breast cancer drug delivery.     

Graphene oxide–polyoctahedral silsesquioxane–chitosan composite films with improved mechanical and water-vapor-transport properties

Graphene oxide (GO) and ball-milled maleamic acid–isobutyl polyoctahedral silsesquioxanes (MAIPSs) were incorporated simultaneously into chitosan (CS) via solution blending to evaluate their combined effects on the structures and properties of composite films. GO and MAIPS aggregates were homogeneously dispersed in CS and affected the crystallinities of the composite films. The binary addition of GO and MAIPS resulted in synergistic enhancements of the tensile strength and elongation at break of the composite films. Composite films containing 3% w/w MAIPS and 0.25% w/w GO (CS–GO–MAIPS-3) exhibited the highest strength and modulus, which were 48 and 42.2% higher, respectively, than the values of the CS film. The water-vapor-sorption isotherms revealed that monolayer sorption sites decreased with the addition of GO or/and MAIPS, but the dissolution process was not significantly influenced. The water-vapor permeability reached its lowest value for the CS–GO–MAIPS-3 film because of hindered diffusion with the presence of impermeable nanoparticles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47748.     

Self-healable and thiol–ene UV-curable waterborne polyurethane for anticorrosion coating

Thiol–ene ultraviolet-curable waterborne polyurethane (WPU) crosslinked networks capable of self-healing of cracks were developed for anticorrosion coating application. The healing mechanism is attributed to the rearrangement of the crosslinked networks caused by triethylamine-catalyzed thiol–disulfide exchange reaction proved by high-performance liquid chromatography, gel permeation chromatography, and rheology tests. The crack remendability can be repeated for at least two times as demonstrated by visual inspection. Moreover, the self-healing effect was further demonstrated in terms of corrosion and electrochemical tests. Comparatively, the control specimens without disulfide bonds were not self-healable. The present study provides a simple way for achieving self-healing WPU to conform to the trend of development of high performance and environmental friendly anticorrosive coatings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47700.     

Effects of hard-segment compositions on properties of polyurethane–nitrolignin films

Segmented polyurethane (PU) films from castor-oil-based PU prepolymer with different hard-segment compositions and nitrolignin (NL) were synthesized. Diisocyanates (DIs), such as 2,4-tolylene DI (TDI) and 4,4′-diphenylmethane DI (MDI), 1,4-butanediol (BDO) as a chain extender, and trimethanol propane (TMP) as a crosslinker were used to obtain PU films containing NL (UL) which were named as UL–TB for TDI and BDO, UL–TT for TDI and TMP, UL–MB for MDI and BDO, and UL–MT for MDI and TMP, respectively. The mechanical properties and thermal stability of the films were characterized by a tensile test and thermogravimetric analysis, respectively. The MDI-based UL films exhibited a higher tensile strength (σ_b) and thermal stability than TDI-based UL. However, the recoverability of the TDI-based UL films was better than that of others. The UL films with TMP (UL–TT and UL–MT) had higher σ_b and lower breaking elongation (ϵ_b) than the UL films with BDO (UL–TB and UL–MB), caused by enhancement in the crosslinking network of hard segments and microphase separation between soft and hard segments. The values of σ_b and ϵ_b of the UL films that contained NL were much higher than those of the PU films, which indicates that the introduction of NL increased the interaction between hard segments by crosslinking. The hydrogen bonding in the UL films was studied by infrared spectroscopy, which indicated that MDI favored the formation of hydrogen bonds, especially in the ordered domain. Differential scanning calorimetry, dynamic mechanical analysis, and wide-angle X-ray diffraction indicated that the UL films were compatible as a whole, but microphase separation existed between soft and hard segments and significantly affected the mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3251–3259, 2001     

Antioxidant capacity of robust polyaniline–ethyl cellulose films

Ethyl cellulose films containing up to 17% polyaniline (PANI EC film) were prepared from ethanolic solutions. The antioxidant capacity of the PANI EC films was examined using the oxygen radical absorbance capacity (ORAC) assay, and the films demonstrated very efficient peroxyl free radical scavenging activity. A good correlation was also obtained between the net ORAC curve area and the size of the tested film, indicating the homogenous dispersion of active PANI powder across the film. Reduced PANI presented greater peroxyl radical scavenging activity than more oxidized as-prepared forms. The influence of the PANI EC films on the oxidation of Ropufa oil was determined after incubation at 60 °C for several days. The oil stored in the presence of a PANI EC film was found to exhibit a lower peroxide value than in the absence of PANI, indicating that the conducting polymer can inhibit the oxidation of fish oil.     

In situ synthesis and interfacial bonding mechanism of SiC in MgO–SiC–C refractories

Adding SiC directly to MgO–C refractories possesses the disadvantages of low dispersion and interfacial bonding strength. Herein, the in situ synthesized SiC was introduced into the MgO–SiC–C refractories to maintain the original excellent performance of MgO–C refractories and reduce the carbon dissolution in molten steel. With the increase of Si and C content in raw materials, the morphology of SiC changed from whisker to network, whose growth mechanism was vapor–solid and vapor–liquid–solid. The network structure and uniform distribution of SiC improved the thermal shock resistance of MgO–SiC–C refractories. According to the analysis of molecular dynamics simulation by Materials Studio software, SiC strengthened the relationship between periclase and graphite to enhance the structure of the compound.     

TaSi2–SiC high-emissivity coating modified by SiB6 on flexible alumina fibre fabric with enhanced oxidation resistance and high interfacial bonding strength

To improve the oxidation inhibition of TaSi₂-based high-emissivity coatings at high temperatures, TaSi₂–SiC coating modified by SiB₆ was prepared on the surface of alumina fibre fabrics. The effects of the SiB₆ content on the surface appearance and emissivity of the coating were investigated, and the mechanical properties of the coated fabrics were compared. When the SiB₆ content in the coating was 2.5%, the borosilicate glass liquid phase generated by SiB₆ oxidation effectively prevented the oxidation of TaSi₂. The bond strength between the coatings and fibre fabric was 207 kPa after calcination at 1200 °C, which was 39% higher than that of the coated fabric without SiB₆. The emissivity of the TaSi₂–SiC coating, modified by a SiB₆ content of 2.5%, reached above 0.92 after calcination at 1200 °C for 5 h. Therefore, the TaSi₂–SiC high-emissivity coating modified by SiB₆ has good application prospects in the field of thermal protection.     

Controlled release and enhanced antibacterial activity of salicylic acid by hydrogen bonding with chitosan☆

Microcapsules of salicylic acid(SA)with chitosan were prepared by spray drying method.Various analytical methods were used to characterize the nature of microcapsules.Fourier-transform infrared spectroscopy(FTIR)confirmed the presence of intermolecular interactions between chitosan and SA.Particle size analysis showed that the average size of microcapsules ranged from 2 to 20 μm.Scanning electron microscopy(SEM)studies indicated that the microspheres were spherical and had a relatively smooth surface.Microbiological assay of antibacterial activity for SA and its microcapsules was measured using different bacterial strains.It was found that the antibacterial activity of SA was improved after the formation of microcapsules.The in vitro release profile showed that the microcapsules could control SA release from 1 h to 4 h.Kinetic studies revealed that the release pattern follows Korsmeyer–Peppas mechanism.Enhanced antibacterial activity of the SA microcapsules was attributed to the synergistic effects of intermolecular hydrogen-bonding interactions N–H?O and O–H?O_C between SA and chitosan.It was also confirmed by quantum chemical calculation.     

Synthesis of waterborne polyurethane–silver nanoparticle antibacterial coating for synthetic leather

An antibacterial coating composed of silver nanoparticles and waterborne polyurethane was synthesized for use on synthetic leather. In this study, silver nanoparticles were prepared and used as nanofiller to impart antibacterial property. Silver nanoparticles were synthesized by using poly(vinyl pyrrolidone) as dispersant and sodium borohydride (NaBH₄) as reducing agent. Silver nanoparticles were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analysis. The optimum dispersant was selected according to the zeta potential of dispersions. Waterborne polyurethane was synthesized by using isophorone diisocyanate, 2-bis(hydroxymethyl)propionic acid, triethylamine, and polytetramethylene ether glycol. Waterborne polyurethane–silver antibacterial coating was obtained by ultrasonic dispersion, and then cast on the surface of synthetic leather. The antibacterial property and coating adhesion were investigated. The results showed silver nanoparticles homogeneously dispersed in waterborne polyurethane and adhesion reaching grade 4. Antibacterial testing showed bacterial reduction of 99.99% for Escherichia coli and 87.5% for Staphylococcus aureus.     

Effect of Cu strike coating on adhesion between Cu–Sn coated steel and rubber

In order to improve the adhesion between steel and rubber, a novel coating deposition technique has been developed, where steel substrate with orchestrated surface roughness was coated with double-layer coatings consisting of a thin Cu strike layer followed by a Cu–Sn layer with varying Sn compositions by immersion route. Coating surface characteristics studied using scanning electron microscope coupled with energy dispersion spectroscopy analyzer, electron probe micro analyzer, and inductively coupled plasma optical emission spectroscopy showed improvement in surface coverage with coating after employing the strike layer coating attributed to the better coating penetration in the deep roughness troughs. Peel test of the coated samples vulcanized with styrene butadiene rubber (SBR) was carried out which showed improvement in adhesion strength of the double-layer-coated samples inferring more uniform Cu-sulfide layer formation at interface due to more uniform coating coverage in these samples. Highest peel strength with uniform cohesive fracture within rubber was observed for optimum 2–3?wt% Sn content in the coatings. This result was further supported by pull-out test conducted on coated wire samples vulcanized with SBR.     

Optimization of SiC–ZrC high emissivity composite flexible coating for thermal protection with high interfacial bond strength and temperature resistance

Aluminum silicate fiber fabric (ASFF) has been widely used in the outer surface of flexible insulation felt on the leeward side of aerospace vehicle. In order to improve the temperature resistance of ASFF, a kind of SiC–ZrC composite coating was prepared on the surface of fiber fabric via spraying method with SiC as emittance agent and ZrC as additive. The surface morphology and mechanical properties of the coating were studied. Compared with the single-component SiC coating, the composite coating could effectively avoid coating spalling and improve the surface integrity at high temperature. After thermal treatment at 1100 °C for 2 h, the interface bond strength of the composite coating/substrate was 52.41% higher than that of SiC coating/substrate. The tensile strength of fiber fabric with SiC–ZrC composite coating could reach 91.75 MPa, which was 101.76% higher than that of raw ASFF. Therefore, the SiC–ZrC coating could greatly improve the temperature resistance of ASFF, and has an attractive application prospect in the field of thermal protection system.     

Preparation and characterization of chitosan–zeolite composites

Double crosslinked chitosan–zeolite (CZ-2) and noncrosslinked chitosan–zeolite (CZ-0) composites were prepared and characterized by using Fourier transform infrared (FTIR) spectrometer, surface area analyzer, scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX) spectrometer, thermogravimetric analyzer (TGA), X-ray diffraction analyzer (XRD) and carbon, hydrogen, nitrogen (CHN) analyzer. After crosslinking, CZ-2 showed a reduction in surface area and CHN content in comparison to chitosan, zeolite, and CZ-0. Crosslinking resulted in improved stability of CZ-2 in distilled water, acetic acid and NaOH as CZ-2 recorded the lowest percentage of swelling. XRD diffractograms confirmed the formation of composites as there was a marked difference in the peak intensity at 2θ = 19.8°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and mechanism of active Mo–Mn metallization on ZTA particles surface and interfacial bonding of reinforced iron matrix composite

ZrO₂ toughened Al₂O₃ particles (ZTAp) have poor wettability with iron, and therefore some defects are easily formed at the interface between ZTAp and iron matrix, which may lead to material failure. This paper illustrates that the ZTAp were modified on the surface by the active Mo–Mn metallization, and thus, they were used as the reinforcing phases to prepare the iron-matrix composite (ZTAp/Fe composite). It is concluded that the sponge-like skeleton structure was formed on the surface of ZTAp after the metallization. The interface of ZTAp/Fe composite, which has been proved to have bearing and transitional capacity by scratch test, was formed by chemical bonding with elemental diffusion, besides mechanical bonding. The metallization mechanism of elemental diffusion can be explained by the migration of glass phase, and the elements diffusion between the interface and iron matrix is to form solid solution.     

Synthesis and Properties of Polymers with an Organosilicon–Acetylene Backbone

Acetylene- and diacetylene-containing organosilicon polymers continue to be of great interest in academia, government, and industry due to their high thermo-oxidative stability combined with excellent solubility and processability characteristics. Progress in this field over the past 30 years is reported herein. We present and discuss the synthesis, characterization, and structure–property relationships related to these materials. Furthermore, properties for specific applications of these polymers are briefly summarized, such as absorption and emission spectroscopy, composite mechanical analysis, four-probe conductivity measurements, and electroluminescence.     

Surface texture and barrier performance of poly(lactic acid)–cellulose nanocrystal extruded-cast films

In this study, we assessed the influence of cellulose nanocrystal (CNC) addition level (0.5–2 wt %) on the surface texture, thickness, and barrier properties of poly(lactic acid) (PLA) extruded-cast films. Regardless of the CNC content, the addition of CNC increased the surface average roughness and maximum roughness of the PLA films in both the machine and cross-machine directions because of the presence of CNC agglomerates. The increased roughness resulted in films with uneven thicknesses; this affected their accurate measurements with a conventional micrometer. Rather, accurate thickness measurements were obtained through the density method, a more appropriate thickness measurement method for films with rough surfaces. The permeability values were negatively correlated with the increased crystallinity. Both the water vapor permeability and oxygen permeability (OP) values decreased significantly by approximately 26–45 and 25–50%, respectively, as the CNC content increased from 0.5 to 2 wt % because of the tortuosity effect. The OP values of the neat PLA and composite films remained insensitive to changes in the relative humidity (from 0 to 75%) when they were tested at 23 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47594.     

Fabrication of composition-graded collagen/chitosan–polylactide scaffolds with gradient architecture and properties

Chitosan–polylactide (CH–PLA) copolymers with various polylactide percentages changing from around 14 to 40 wt% were synthesized. CH–PLAs were then blended with type-II collagen to fabricate layered collagen/CH–PLA scaffolds that are potentially suitable for the applications in articular cartilage repair. Based on combinatorial processing techniques involving layer-superposition, thermal melting and freeze-drying, two types of stratified collagen/CH–PLA scaffolds were built. The content of collagen inside the scaffolds altered from the top layer to the bottom layer in a trend contrary to that of chitosan. One of them was fabricated using tripolyphosphate (TPP) as a single crosslinker and another type of scaffold was constructed via a dual-crosslinking pathway using TPP and genipin as two crosslinkers in a designated order. These collagen/CH–PLA scaffolds were found to have graded average pore-size and porosity, gradient swelling index and layer-dependent compressive modulus. The resulting scaffolds were thus partially similar to the articular cartilage extracellular matrix in composition, structure and property. In vitro cell culture on some optimized collagen/CH–PLA scaffolds for a period of time up to 3 weeks showed that the scaffolds were able to well support the growth of the seeded cells, suggesting that these collagen/CH–PLA scaffolds have promising potential for articular cartilage repair.     

Preparation and properties of novel corn straw cellulose–based superabsorbent with water-retaining and slow-release functions

In this study, novel semiinterpenetrating polymer networks (semi-IPNs) superabsorbent resins with slow-release fertilizer (CSC-g-AA/APP, CSC-g-AA/PVA-APP), based on corn straw cellulose polymer and linear polyvinyl alcohol (PVA), were prepared by solution polymerization. The nitric acid-aqueous solution method was adopted to extract cellulose from corn straw. Ammonium polyphosphate (APP) was introduced to supply nitrogen and phosphorus nutrients. The prepared materials were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Moreover, the water absorbency and the slow-release performance of CSC-g-AA/APP and CSC-g-AA/PVA-APP were studied. The results indicated that the two superabsorbent resins exhibited excellent water absorbency of 262.8 and 303.2 g/g in distilled water, enhanced the water-holding capacity of soil, and also released nutrients slowly. The cumulative N and P release rates of CSC-g-AA/PVA-APP were 64.47 and 53.53% after 25 days in soil, which were lower than those of CSC-g-AA/APP. The addition of these products into soil significantly reduced the leaching losses of nutrients. Therefore, it can be concluded that the superabsorbent resins with water-retaining and slow-release properties, low production costs, and environment-friendly characteristics, have great potential for applications in agricultural production. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48951.     

Preparation and properties of bisphenol A epoxy resin microcapsules coated with melamine–formaldehyde resin

Microcapsules containing epoxy resins have potential applications, such as in adhesive, electronic packaging, and self-healing polymeric composites. A series of microcapsules were prepared by in situ polymerization with poly(melamine–formaldehyde) as the shell materials and a mixture of diglycidyl ether of bisphenol A and epoxy diluent as the core substances. Morphology, chemical structure, mean particle size, and thermal properties of the microcapsules were studied by means of optical microscope, Fourier transform infrared spectroscopy, laser particle size analyzer, and microcomputer differential thermal balance, respectively. Effects of kind of epoxy diluent, surfactant type, emulsifier concentration, and emulsifying rate on the physical properties of microcapsules were investigated. Results indicate that the formation of microcapsules is affected by the epoxy diluent type and surfactant type. The highest core content of the resultant microcapsules is about 88 wt% and average diameters of the capsules range from 67 to 201 μm, which can be adjusted by changing the emulsifier concentration and emulsifying rate. Thermo gravimetric analysis indicated that the prepared microcapsules experienced excellent stability up to 235 °C.