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 μm 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.
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.
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.
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.
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.
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.
A more sustainable dialysis and water filtration membrane has been developed, by using the new, safer, bio-based solvent Cyrene (R) in place of N-methyl pyrrolidinone (NMP). The effects of solvent choice, solvent evaporation time, the temperature of casting gel, and coagulation bath together with the additive concentration on porosity and pore size distribution were studied. The results, combined with infrared spectra, SEM images, porosity results, water contact angle (WCA), and water permeation, confirm that Cyrene (R) is better media to produce polyethersulfone (PES) membranes. New methods, Mercury Intrusion Porosimetry (MIP) and NMR-based pore structure model, were applied to estimate the porosity and pore size distribution of the new membranes produced for the first time with Cyrene (R) and PVP as additive. Hansen Solubility Parameters in Practice (HSPiP) was used to predict polymer-solvent interactions. The use of Cyrene (R) resulted in reduced polyvinylpyrrolidone (PVP) loading than required when using NMP and gave materials with larger pores and overall porosity. Two different conditions of casting gel were applied in this study: a hot (70 degrees C) and cold gel (17 degrees C) were cast to obtain membranes with different morphologies and water filtration behaviours.
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.
Topological insulator two-dimensional (2D) Bi2Se3 hexagonal nanoplates, which are highly insulating in the bulk and have a conductive topological surface state, have been prepared via an EG- (ethylene glycol-) sol method and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Bi2Se3/PVDF (polyvinylidene fluoride) nanocomposites with various Bi2Se3 contents have been fabricated by a tape-casting method. The microstructure and dielectric performance of the Bi2Se3/PVDF nanocomposites are studied. The dielectric constant of the dense nanocomposite films keeps a relatively low value of about 16 when the Bi2Se3 content is lower than 12 vol.% then suddenly increases to 36 with a critical Bi2Se3 content of 13 vol.% due to the percolation effect of the large aspect ratio of the 2D Bi2Se3 nanoplates. The study of the Bi2Se3/PVDF nanocomposite system is conducive to the exploration of high-performance dielectrics.
Temperature stability is critical to the consistency of product quality in the injection molding process, and it is very necessary to improve the temperature control accuracy under dynamic conditions. However, due to the large time delay, strong coupling, and the dynamic characteristics existing in the system, it is not an easy task to achieve precise temperature control in the injection molding process. In this paper, a new intelligent temperature compensation control strategy for the injection molding process under dynamic conditions is proposed in order to solve two key problems in the compensation control strategy: the compensation time and compensation quantity. A data-based feedforward iterative learning control (ILC) algorithm is designed to learn the optimal compensation time. Once the optimal compensation time is learned, a deep Q-learning algorithm which combined Q-learning with an artificial neural network (ANN) is proposed to learn the optimal compensation quantity. An experimental platform is designed to validate the superiority of the proposed method. Experimental results show that the proposed method can effectively improve temperature control accuracy under dynamic conditions. Meanwhile, the product consistency has also been improved.
Some fiber types have a high aspect ratio and it is very difficult to predict their composites using traditional finite element (FE) modeling. In this study, an FE model was developed to predict the anisotropy of composites reinforced by short aramid fibers. Three fiber distribution types were studied as follows: perfectly aligned, normally distributed, and randomly distributed fibers. The elastic constants were obtained, and, for different alignment angles and parameters in the fiber orientation distribution function, their numerical results were compared to those of the Mori-Tanaka model. Good agreement was obtained; thus, the employed FE model is an excellent and simple method to predict the isotropy and anisotropy of a composite with high-aspect-ratio fibers. Therefore, the FE model was employed to predict the orientation distribution of a composite fiber with a nonlinear matrix. The predicted and experimental results agree well.
The ozonization modification of polystyrene (PS) was conducted in acidic condition to enhance the interfacial interaction between PS and polyvinyl alcohol (PVA). Infrared spectra results revealed that the carbonyl and hydroxyl groups were successfully introduced to the PS film by ozonization. The hydrophobic PS was turned to be hydrophilic to some extent by contact angle experiment, which led to the enhancement of interfacial adhesion between PS and PVA. In addition, the adsorption of PS to PVA was also improved. Nano indenter measurement indicated the interfacial interaction between PS film and PVA film was obviously enhanced by 40% after ozonization at room temperature for 2h in acidic condition, which will benefit for fabricating laser inertial confinement fusion container.
With the increasing demands of environmental protection, the properties of water-borne coatings film must meet or exceed current solvent-based coatings. It is an important part of coating science for characterizing the film properties of polymers which was used in the water-borne and the solvent-based coating. In this study, UV-visible spectroscopy, gravimetric analysis, scanning electron microscopy, and electrochemical impedance spectroscopy were used to characterize the properties of the water-borne and the solvent-based poly(butyl acrylate/styrene) (P(BA/St)) copolymer films. The water-borne and the solvent-based P(BA/St) copolymer was synthesized by two methods. The copolymer had a Tg of approximately 14.4 degrees C, which was close to room temperature. The water-borne copolymers were prepared via a three-step film formation process, while the solvent-based copolymer films were prepared in two steps. Comparing the properties of the water-borne and the solvent-based films, the water absorption capacities decreased with increasing film formation times, and the film barrier properties and electrochemical properties of both films improved as the film formation time increased.
Antibacterial and biodegradable whey protein isolate (WPI-) gelatin nanocomposites were prepared using natural orange peel extract (OPE) in percentage of 7, 14, and 21% (v/v solution) and Cloisite 30B (5% w/w dry whey protein) made by a casting method. Mechanical, physical, and antibacterial properties of prepared films were measured as a function of OPE concentration. Higher concentrations of OPE led to higher antibacterial activity, tensile strength, and water solubility, but lower moisture content and transparency. The films microstructures were studied by field emission scanning electron microscopy (FESEM) and ATR-FTIR. Overall, the film containing 21%(v/v) OPE resulted in the best antibacterial, mechanical, and physical performance. Addition of tripolyphosphate (TPP) as a crosslinker to this sample led to the significant increase in transparency. Cloisite 30B, OPE, and TPP can therefore be used to improve the properties of WPI films as a promising natural food packaging.