Gallic Acid-loaded Cellulose Acetate Electrospun Nanofibers: Thermal Properties, Mechanical Properties, and Drug Release Behavior

The gallic acid-loaded electrospun cellulose acetate fibers were successfully prepared. The fiber containing 2.5% gallic acid was smooth surface but observed drug flake on the surface of the fiber when increasing drug content. The thermal properties, mechanical properties and drug release behavior of the fibers were investigated comparing to the corres-ponding films.

Porous Electrospun Nanofiber from Biomass-Based Polyester Blends of Polylactic Acid and Polybutylene Succinate

We studied the electrospinning process of the blend of polylactic acid (PLA) and polybutylene succinate (PBS). The blend PLA/PBS ratio 95/5, 90/10, 85/15 and 80/20 wt% were prepared by dissolved in mixture of solvent between dichloromethane (DCM) and N, N-dimethylformamide (DMF) at ratio 3/1. The suitable condition for electrospun of the blend was 17% wt concentration, 16 kV and 18 cm projection distance. The round fiber with pore on the surface was observed. Increasing content of PBS in the blend impact to the diameter of fibril decreased from 1350, 1290, 1210 and 1170 nm, respectively;while the pore on the surface changes from circle to oval shape. Regarding the thermal properties, blending of PBS increases the glass transition temperature (Tg) of PLA without affect to the melting temperature (Tm) of the electrospun nanofibers. The best tensile properties of PLA/PBS nanofibers were achieved at blend ratio of 95/5, and Young’s modulus is increased comparing to those of the pure electrospun fibers.

Natural Rubber/Fluoro Elastomer Blends: Effect of Third Component on Cure Characteristics, Morphology,Mechanical Properties, and Automotive Fuel Swelling

The natural rubber (NR) was mixed with fluoro elastomer (FKM), due to the difference of polarity in NR and FKM made this blend incompatible so the third component was used. NR/FKM blended with the blend ratio of 70/30 was prepared by using a two-roll mill and vulcanization in a compression mold at 180℃ using peroxide as a curative agent. Epoxidized natural rubber (ENR) or polyisoprene-graft-maleic acid monomethyl ester (PI-ME) was used as a third component. The curing characteristics, morphology, mechanical properties, and automotive fuel swelling were investigated. The results indicated that the scorch time and cure time of the blend rubbers were longer as adding ENR or PI-ME. Both mechanical properties and automotive fuel resistance of the blend rubbers were found to increase with adding ENR in rubber blend. Conversely for adding PI-ME, automotive fuel resistance of the blend rubbers was found to decrease progressively with increasing PI-ME content.

Influence of Poly(vinyl chloride) on Natural Rubber/Chlorosulfonated Polyethylene Blends

Blend of natural rubber (NR) and chlorosulfonated polyethylene (CSM) was so interesting due to binding of the good oil resistance of CSM, the good mechanical properties and low cost of NR. However, due to the different polarities of two rubbers, phase separation and inferior properties of NR/CSM blend were obtained. The practical way to improve its properties is the addition of the third component to bind both phases of the blend. Effects of poly(vinyl chloride), PVC as compatibilizer on cure characteristics, morphology, mechanical properties and automotive fuel resistance of NR/ CSM blend were investigated. In this contribution, NR/CSM blend with blend ratio of 50/50 was prepared using a two-roll mill, and then vulcanized in a compression mold at 160°C. The PVC content was varied from 1 to 7 phr. It was found that the usage of 7 phr PVC led to improve interaction between NR and CSM phases. Therefore, increase in cure characteristics, mechanical strength and automotive fuel resistance of the blend was observed.

Cellulose Microfibril from Banana Peels as a Nanoreinforcing Fillers for Zein Films

Cellulose microfibril (CMF) was the extraction with acid mixture from peel of Musa sapientum Linn type of banana (Kluai Nam Wa). The fibrous-shape of CMF interconnected weblike structure with the average diameter 26 nm were observed by TEM. In order to prepare zein/CMF nanocomposite films, 16% wt zein solution was prepared by dissolved in 80% ethanol aqueous solution which contain glycerol 20% w/w. The suspension of CMF and zein solution was mixed with 0% - 5% weight fractions of solid CMF in zein matrix. The morphology of the zein films is more roughness by increased amount of cellulose microfibrils. It was found that as CMF content increase from 0 to 5% wt results in increasing tensile strength and Young’s modulus of zein nanocomposite films. The highest strength obtains at 4% wt CMF.

Improved Automotive Fuel Resistance of Natural Rubber/Chlorosulfonated Polyethylene Blends by Blending Epoxidized Natural Polymer

The natural rubber (NR) was mixed with chlorosulfonated polyethylene (CSM), due to the difference of polarity in NR and CSM made this blend incompatible and the third component was used. Epoxidzed natural rubber (ENR) was used as a third component. NR/CSM blended with the blend ratio of 50/50 was prepared by using a two-roll mill and vulcanization in a compression mold at 160°C. The ENR content was varied from 1 to 7 phr. The curing characteristics, morphology, mechanical properties, and automotive fuel swelling were investigated. The results indicated that the cure time of the blend rubbers was shorter as adding ENR. The mechanical properties of the blend rubbers were not affected by ENR content. However, automotive fuel resistance of the blend rubbers was found to increase with adding ENR in rubber blend.

Investigation of Hot Deformation Behavior of SNCM8 Alloy Steel

Plastic flow behavior of the SNCM8 steel was investigated by performing hot compression tests within the temperature range of 850˚C to 1200˚C and strain rates of 0.01 s−1 to 10 s−1. Constitutive modeling based on dynamic recrystallization was established, in which Cingara equation was applied to represent work hardening up to peak stress and Avrami equation to describe dynamic softening beyond peak stress up to steady state. It was found that stress-strain responses predicted by the combined model fairly agreed with experimentally resulted curves for the particular conditions. The correlation coefficient (R) of 0.9485 and average absolute relative error (AARE) of 2.3614% was calculated for the modeled flow curves.

白炭黑杂化填料填充天然橡胶、丁苯橡胶及其并用胶的硫化特性、物理性能和耐磨性能

天然橡胶（NR）和合成橡胶被用于许多工业橡胶制品中。NR具有优异的拉伸和撕裂性能及良好的耐磨性能,适用于制备O形圈、密封件、轮胎和输送带等。丁苯橡胶（SBR）常用于磨耗场合,但其拉伸和撕裂性能较差,与NR并用及织物补强均有助于提高其物理性能。

Biomass-Based Composite Foam from Tapioca Starch/Octenyl Succinate Starch Blended with Alpha-Chitin

The research study properties of the starch-based foam from mixed between tapioca starch and octenyl succinate starch (OSA starch), have addition alpha-chitin prepared by hot compression molding method. Tapioca starch with 50% OSA starch was investigated. For composite foam tapioca starch mixed by adding alpha-chitin at 5% - 30% of starch weight, it was found that water absorption was reduced. The higher alpha-chitin content in blending foam, the denser of foam structure observed which resulted in increasing of the foam density. The maximum bending stress of composite starch was decreased, but increasing the maximum bending strain.

Influence of Pre-Deformation on Springback Effect of Advanced High Strength Steel

In sheet metal forming process of automotive components,the springback effect is significant,in particular for Advanced High Strength Steels (AHSS),for example the Dual Phase (DP) steel.Most of construction parts of modern vehicles have very complex shapes and therefore multi-step procedures are necessary to form such a part.Steel sheets,which firstly undergo pre-deformation,can show considerable change in mechanical behavior during the forming process.However,at present there are limited sufficient data concerning pre-deformation effect on the springback available.In this work,a study of influences of different pre-strain levels on the springback of steel sheet made of AHSS materials has been carried out.The sheet specimens were firstly pre-stretched on a tensile testing machine and the pre-strain values were calculated based on the engineering strain.Furthermore,the steel sheets prepared parallel,transverse,and 45° to the rolling direction have been investigated.A modified U-shape forming was used to evaluate the degree of springback of the steel sheets under various conditions.In parallel,FE simulation of the U-shape forming was performed.Both isotropic model using stress-strain responses from tensile test of specimens with different directions and anisotropic Hill’s 48 model have been applied.The experimental results are compared with the sheet metal forming FE simulations.The primarily aim is to basically understand the springback mechanism by means of the simple models.And finally,conclusions with regard to the springback modeling will be presented.

Finite element analysis of piping defect formation in the sheet-extrusion process

The pressing process,as compared to the machining process,makes good utilization of work piece material and shortens the production time,and as such it is increasingly used for production of complex shaped parts.A particular type of pressing is sheetextrusion which controls the flow of material into special punch and die sets to produce an extruded shape.However,some particularly complex shaped parts cannot be made by sheet-extrusion due to the formation of piping defects.In this study,the finite element method(FEM)was used to investigate the formation of piping defects.In addition,the relationship between the characteristic dimensions of the extruded shape and the piping defect was also examined.Laboratory pressing experiments were performed to validate the accuracy of the FEM simulation results.Based on the stress distribution and velocity profiles within the extruded work piece,the relationship between the extruded shape and the piping defect was clearly identified.Furthermore,the FEM simulation results showed good agreement with the experimental results with regards to the dimensions of the extruded shape and the piping defect.

Flexible sodium-ion batteries using electrodes from Samanea saman tree leaf-derived carbon quantum dots decorated with SnO_(2) and NaVO_(3)

Carbonaceous materials with large interlayer spacing and disordered structure are considered suitable as electrodes in sodium-ion batteries so as to overcome the problem encountered in conventional electrodes.In this study,carbon quantum dots(CQDs)decorated with SnO_(2)and NaVO_(3)are used as electrodes in the fabrication of flexible Na-ion batteries.CQDs are prepared from dead leaves of the Samanea saman tree through alkaline-peroxide treatment and hydrothermal carbonization.As-prepared CQDs exhibit a quantum yield of 21.03%at an excitation wavelength of 360 nm.Various separators such as indium-doped tin oxide/polyoxyethylene tridecyl ether(ITO/PTE),rice paper(RP),silicone with three big holes(SIL BH),silicone with many small holes(SIL SH)and cellulose paper(CP)have been tried in flexible Na-ion batteries.SIL SH achieved higher specific capacitance(881 F g-1)than other separators due to the function of many small holes on the surface of the silicone.The SIL SH separator delivered higher discharge capacities of 141 and 114 mC g-1 at 1.5 and 2.5 V than SIL BH.The RP separator delivered specific discharge capacities of 1087 and 347 mC g-1 in the 1st and 50th cycles,respectively,at 1 V.The RP separator delivered a high initial specific discharge capacity of 698 mC g-1 at 2 V and maintained a good discharge capacity of 222 mC g-1 in the 50th cycle.As compared to RP,SIL SH delivered high specific discharge capacity of 4246 in 1st cycle at 2 V but maintained a capacity of 71 mC g-1 in the 50th cycle.This study reveals the scope of developing flexible Na-ion batteries with high capacity and cyclability using carbonaceous materials derived from the leaves of the S.saman tree.