Proton‐conductive electrospun nanofibers are promising potential materials for several advanced technological applications such batteries, sensors, and fuel cells. In this work, we prepared poly(vinyl butyral)/polyaniline ( PVB / PANI ) nanofibers via electrospinning and determined their proton conductivities. Structural characterization of the nanofibers was performed by FTIR analysis. Surface morphology of the nanofibers was determined by SEM and AFM . The addition of PANI significantly affected the fiber morphology, and over 90% reduction (with respect to neat PVB nanofibers) in the average nanofiber diameters was observed. Nanofiber mats were doped with polyphosphoric acid. The proton conductivity of the 2 wt.% PANI containing blend nanofibers was found as 18 × 10 −6 S/cm at room temperature and at 100% humidity.
In this study, the tensile strength and M‐Rockwell hardness of polycarbonate (PC)‐nanoalumina composites are investigated under various processing parameters. For this purpose, PC using a twin‐screw extruder is melt compounded with nanoparticle of Al 2 O 3 in the presence of styrene‐co‐maleic anhydride (SMA) as the compatibilizer. Influences of weight percentage of nanoalumina and injection processing parameters including injection pressure and holding pressure (all in four levels) are investigated on tensile and hardness properties of nanocomposite samples using Taguchi's L 16 orthogonal array. The scanning electron microscopy (SEM) results reveal that an appropriate distribution of nanoparticles in polymeric matrix is achieved. According to the results, nanoalumina content is the most effective parameter on tensile strength and hardness with about 51% and 85% contribution, respectively. Results indicate that by addition 1.5 wt% of nanoalumina, the tensile strength and hardness of samples increase as much as 4.5% and 11%, respectively. Also, the results reveal that injection pressure and holding pressure are also effective parameters to change hardness and tensile strength.
Aim of the present work was to develop alginate–pectin rafts by using box behnken design to provide symptomatic relief from gastroesophageal reflux disorders by forming floating gel or raft on the top of gastric contents. Sodium alginate and pectin were used as raft‐forming polymers, sodium bicarbonate as gas‐generating substance, and calcium carbonate for generation of calcium ions. Physical test of all compressed formulations were within pharmacopoeial limits. Effect of pH of medium on raft formation was observed by placing the formulation in different pH mediums. Raft was characterized by their strength, weight, volume, resilience, reflux resistance, thickness, buffering capacity, neutralizing capacity, floating lag time ( FLT ) and total floating time ( TFT ). Fourier transform infrared ( FTIR ) spectroscopy was performed to check the interaction between the polymers and other excipients. Raft was effectively formed at pH 1.2. Raft strength, reflux resistance, and thickness of optimized formulation APR 15 were 9.71 ± 0.013 g, 2670 ± 0.987 g, and 5.1 ± 0.045 cm, respectively. Raft resilience for the APR 15 was found to be greater than 480 min. TFT of APR 15 was greater than 8 hr with 50 s FLT . Buffering and neutralizing capacity were 12.70 ± 1.21 meq and 7.0 ± 0.34 meq, respectively. FTIR spectra showed no interactions between sodium alginate, pectin, and other excipients. This study demonstrated that alginate–pectin rafts are suitable for the treatment of gastro‐esophageal reflux disorders.
The aim of present work is to study the behavior of completely biodegradable starch‐based composites containing okra cellulosic fibers in the range from 5 to 25 wt%. The cornstarch matrix and composites were prepared by using urea–formaldehyde as a cross‐linking agent. The cross‐linked cornstarch matrix and its composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and thermogravimetric analysis. Furthermore, thermal and different mechanical properties, i.e., tensile, compressive, and flexural strength of composites, were also studied. The thermal stability of fiber‐reinforced composite was increased as compared to starch matrix. The mechanical properties of composite such as tensile, compressive, and flexural have been found to increase with the increase in fiber content up to 15% loading. The composite specimens tested for tensile, compressive, and flexural strength at 15% fiber loading exhibited values of 17.78 ± 0.89, 33.55 ± 1.67 and 60.1 ± 3.01 MPa, respectively. Furthermore, the matrix and composites were subjected to biodegradation studies through the soil burial method.
To solve the quality problem of polymer injection parts, a quality prediction and multiobjective optimization method is established. In this method, the parameters that have an important effect on the part quality are selected using an orthogonal testing method, and then a central composite design experiment is performed using these parameters. A mathematical model considering an objective and impact factors is developed using the response surface method. The optimal combination of the impact parameters is determined using a multiobjective genetic algorithm. The injection molding of a typical interior trim part of a car, i.e., the seat belt cover plate, is used as an example to demonstrate the method. The two most troublesome problems in this process-the sink marks and warpage-are multiobjectively analyzed using the established method, and the optimal combination of impact parameters that minimized the defects is determined. The errors of the sink marks and warpage between the experimental and theoretical values were 7.95% and 0.2%, respectively. The optimized parameters were tested in actual injection molding. The results show that the shrinkage and warpage of the parts are obviously improved by optimization using the proposed method, allowing the parts to satisfy the requirements of assembly and appearance.
RS-4050 is a rigid epoxy based magnetic castable microwave absorbing material; it has been used in many areas of waveguide application as a microwave waveguide terminations and dummy loads. In recent years, there is a demand for composites material with lower dielectric constant higher loss factor for microwave application. This research, the effect of soda lime silica (SLS) on structural and complex permittivity of soda lime silica-high density polyethylene (SLS-HDPE) composites was conducted in order to explore the possibility of substituting RS-4050 with SLS-HDPE composites as a microwave waveguide terminations and dummy loads. Elemental weight composition of the SLS glass powder and HDPE was identified through scaling of different percentage of SLS and HDPE. X-ray diffraction (XRD) was used to investigate the crystallinity behavior of SLS-HDPE composites. The proposed SLS-HDPE composites material was studied at frequencies 8 to 12 GHz. The study was conducted using waveguide Agilent N5230A PNA technique. The effect of microwave frequency on complex permittivity properties for SLS-HDPE composites of different percentages of SLS and HDPE (10% SLS-90% HDPE, 20% SLS-80% HDPE, 30% SLS-70% HDPE, 40% SLS-60% HDPE, and 50% SLS-50% HDPE) were investigated. Results showed the diffraction patterns reveal good amorphous quality with a genuinely properties structure. The microwave frequency and composites percentages significantly influenced the complex permittivity (real and imaginary) properties of the composites. Moreover, the complex permittivity increased as the percentage of SLS filler increased in the host matrix HDPE as a result of increased in composite density due to less volume being occupied by the filler as the percentage increased. The complex permittivity of the smallest and largest percentages of SLS (10% and 50%) was (2.67-j0.05) and (3.45-j0.35), respectively. The study revealed that the best sample for waveguide application as microwave terminator is 50% SLS as it has the highest dielectric constant, highest loss factor, and highest loss tangent as compared to 10% SLS to 40% SLS. Also 50% SLS has the highest absorption properties as compare to 10% SLS, 20% SLS, 30% SLS, or 40% SLS. The XRD physical structure of the SLS-HDPE composites revealed the absorption characteristics of different percentages of the materials. The SLS-HDPE composites can be applied in the area of waveguide as a microwave waveguide terminations and dummy loads.
In this work, we presented a facile pathway to fabricate polyanionic cellulosic microparticles by selective oxidation with sodium periodate firstly, followed by grafting sodium bisulfite to the 2,3-dialdehyde cellulose particles. The obtained polyanionic cellulosic microparticles with the particle size of 2-4 mu m had increased stability in water, and it had pH responsiveness. Moreover, the polyanionic cellulosic microparticles had excellent film-forming property, and the tensile strength of the film formed from pristine cellulose particles was about 40 MPa, and it increased to 64 MPa for the film formed from SRC-50 particles. Furthermore, the polyanionic cellulosic microparticles had certain reduction ability, and it could be used as coating to cover the surface of fruits or vegetables, and it could prevent the discoloration of the fresh-cut potato. The cellulose based particle coating with excellent antibrowning capacity, biocompatible, and environmentally friendly characteristics would be attractive for the applications in packaging material for food preservation.
Poly(aminoamide) ( PAMAM ) dendrimer with 3.5 generation was synthesized with ethylenediamine as the primary core and methyl acrylate. Also, Fe 3 O 4 nanoparticles as magnetic ones were modified by (3‐aminopropyl)triethoxysilane ( APTES ) to fabricate amine‐functionalized magnetic nanoparticles (Fe 3 O 4 @ APTES ). Then, 3.5 GD dendrimer was conjugated with Fe 3 O 4 @ APTES to obtain dendrimer‐grafted magnetic nanoparticles (Fe 3 O 4 @3.5 GD ). The core‐shell structure of Fe 3 O 4 @3.5 GD nanoparticles was revealed via TEM . Also, progression of each step was studied by FT ‐ IR , 1 H NMR , CHN elemental analysis, and thermal gravimetric analysis (TGA) . Vibrating sample magnetometer ( VSM ) was used to show that the synthesized nanoparticles keep their superparamagetic properties after synthesis process. Finally, in vitro cellular cytotoxicity was applied to evaluate the biocompatibility of synthesized structures and investigate the cytotoxic effect of grafted dendrimer using HeLa cells. As a resultS, about 20 wt. % of dendrimer grafting was obtained and good correlation was observed with VSM results. Also, 3.5 GD dendrimer showed low cytotoxicity to HeLa cells while after dendrimer grafting, toxicity of Fe 3 O 4 @3.5 GD slightly increased.
The present investigation reports the greener synthesis and characterization of novel acrylic acid grafted amphoteric chitosan/TiO2 (CAT) bionanocomposites using ultrasonic radiations. This was done by grafting of acrylic acid onto chitosan in the presence of potassium persulfate by free radical polymerization reaction. The uniform distribution of metal oxide in CA/TiO2 nanocomposites was achieved on grafted acrylic acid/chitosan which contains a weak anionic group (-COOH) using ultrasonication technique. Physiochemical techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Fourier Transform Infra-Red spectroscopy (FT-IR), Energy Dispersive X-ray spectroscopy (EDX), and Thermal Gravimetric Analysis (TGA) were employed to characterize synthesized CAT. Nanocomposite CAT was applied for degradation of industrial dye. Malachite green (MG) often presents in the waste waters. The degradation kinetics were studied by monitoring the photocatalytic reaction for degradation of MG under visible light, and the rate constant of the reaction was found to be 7.13x10(-3)min(-1). The current research work opens vistas for the new dimensions in the area of water treatment by solving the issues related to degradation reaction efficiency in visible light and cost effectiveness.
We performed xylanase pretreatment prior to mechanical refining in the production of mulberry branch fibers, with the objective of saving energy and studying the effects of such pretreatment on the quality of the fibers. To determine the effects of the enzyme action, we analyzed the energy required for refining, related yield, and the dimension, deformation, and morphology of the fibers. We found that, with the xylanase pretreatment, the refining energy was reduced by 4%, with the yield of fibers being maintained at >85%. In addition, the fiber bundles were defibered further, resulting in reduced average length of the fiber. Furthermore, the fiber widths increased because of the improved swelling effect of the xylanase pretreatment. However, in some instances, the fine elements were reduced. With a low enzyme dosage, the fiber coarseness decreased remarkably and, because of the swelling and softening effects of the xylanase pretreatment on the mulberry branches, the fiber kink ratios and curl were reduced. Additionally, the mulberry branch tissue was loosened, facilitating fiber separation. In view of these findings, the biomechanical process could be a potentially green and efficient process for the manufacturing of mulberry branch fibers.
Polypropylene (PP) powder with spherical morphology and suitable particle size for selective laser sintering (SLS) was successfully produced by dissolution-precipitation method. The influence of preparation condition on properties of PP powder was investigated. The experimental results show that the optimal preparation conditions are as follows: dissolution temperature being about 166 degrees C, pressure being about 0.7MPa, and the solid-to-solvent ratio being about 0.067g/ml. The prepared PP powder displayed a narrow size distribution with the mean size of about 42.7 mu m and the apparent density of powder about 0.40g/cm(3). The specimens produced by laser sintering of the PP powder showed smooth appearance and good dimensional accuracy. The tensile strength and impact strength of the sintered parts were 27.9MPa and 6.3KJ/m(2), respectively, which are basically equal to the properties of the injection molded parts.
At present, China is the world's largest producer of bamboo resource possessor and bamboo processing. The main processing method of bamboo recombination technology is rolling and compaction, by which a reconstituted material with bamboo fibrotic veneer as matrix and phenolic resin as reinforcement is prepared. It has excellent physical and mechanical properties and can replace high-quality wood to manufacture various engineering structural materials and building decoration materials. This paper reviewed the research process and progress of bamboo recombination technology, the existing technical problems and prospects, in order to provide references for future research on bamboo recombination theory and production practice. In recent years, as a new material with controllable properties, designable structures, and adjustable dimensions, bamboo reconstituted materials have been comprehensively studied from the aspects of pressing process parameters, physicochemical mechanical properties evaluation system, and microstructure characterization, but the research is not comprehensive and has not in-depth view. In the future, the relationship between microstructure and performance should be emphatically studied to clarify the law of mechanical performance change and ultimate mechanical performance under synergistic enhancement effect, as well as the performance change and interface formation of the resin during the entire molding process. Meanwhile, the reliability and relevance of applied research should be further expanded, and the integration of natural and artificial aging environment, process and performance, and macro- and microscales should be strengthened.
Natural wood has certain advantages such as good processability and high specific strength and thus has been used for millennium as a structural material. But the mechanical performance and water resistance, particularly for fast-growing species, are unsatisfactory for high-end applications. In this study, the new-type scrimber technology was introduced to radiata pine (Pinus radiata D. Don) scrimbers. The structure, mechanical properties, and dimensional stability of the scrimber panels were investigated. Results showed that OWFMs as basic units of scrimber had been very even in size and superior permeability. The scrimbers exhibited a three-dimensional porous structure, and the porosity had a decrease with increasing density. Both OWFMs and densification contributed to the high performance in terms of mechanical properties and water resistance. The flexural, compressive, and short-beam shearing strength were significantly enhanced with increasing density. As the density was 0.80g cm(-3), the flexural strength (MOR) was approximately 120MPa, much larger than many selected wood-based panels. Moreover, the water resistance and dimensional stability also were closely related to the density. At the density of 1.39g cm(-3), the water absorption rate and thinness swelling rate of the panels in boiled water were only 19% and 5.7%, respectively.
The 4‐(2‐bromoisobutyroyl methyl)styrene [ BBMS ] monomer was synthesized. The homopolymer of BBMS was prepared by free radical polymerization method. The decomposition behavior of P( BBMS ) was thermally investigated by thermogravimetric analysis ( TGA ). For thermal decomposition kinetics of poly( BBMS ), Flynn–Wall–Ozawa method was applied to thermogravimetry curves. The first step, which is one of the two decomposition stages, is comprehensively related to elimination of hydrogen bromide and the other step is related to a multi‐step process. The activation energy ( E a ) of thermal decomposition of the first step and 50% weight loss is 148.5 and 190.7 kJ/mol, respectively. The results showed that the side group elimination without chain breaking comprehensively proceeded at lower temperature, and at progressive temperatures subsequently the specific chain scission did so. Degradation of poly( BBMS ) did not lead to depolymerization. 1 H, 13 C‐ NMR , and FT ‐ IR analyses showed that the decomposition products during degradation of poly( BBMS ) to 260°C were comprehensively HB r and methacrylic acid. Electrically conducting graphene‐based poly( BBMS ) composites were prepared. The DC and AC electrical measurements of graphene‐based poly( BBMS ) composites were carried out. The AC dielectric measurements of poly( BBMS ) were investigated up to 70°C between 100 Hz and 20 kH z depending on the alternating current conductivities. The dipolar functional groups (C–O, C=O, and Br) of the BBMS segment possesses significantly affect the dielectric constant. Also, the activation energy profile of different graphene/poly( BBMS ) composites were revealed by measuring DC conductivity of individual composite material.
In this study, a molecularly imprinted polymer ( MIP )‐fluorescent probe based on hydrophobic CdSe/ZnS quantum dots (CdSe/ZnS@ MIP ) was designed and synthesized by bulk polymerization for detecting methamidophos ( MAP ). The CdSe/ZnS@ MIP was characterized by Fourier‐transform infrared spectroscopy, thermo‐gravimetric analysis and adsorption properties, and it exhibited good adsorption capacity and fluorescent stability, and excellent selectivity. Under optimal conditions, the fluorescence showed a good linear decrease in the range of 3.50 × 10 −7 –0.71 × 10 −3 mol/L with a correlation coefficient of 0.995. The limit of detection of the fluorescent probe was 9.16 × 10 −8 mol/L, and the relative standard deviation of the method for nine replicate analyses of 4.0 × 10 −6 mol/L MAP was 4.1%. Apple and pear samples spiked with MAP at three levels were extracted and determined by the presented method with good recoveries (89.7%–94.9%). The accuracy of the method was verified by gas chromatography for the detection of kidney beans, leek and cucumber samples, and no significant difference was observed for the results of two methods.