Elevated Tensile Strength Research Articles

Research on the ultra-low temperature tensile deformation mechanism of Al-Mg-Si alloys in different heat treatment states

The susceptibility of Al-Mg-Si alloy to cracking during room temperature large plastic deformation poses a significant obstacle to its widespread application. Cryogenic temperature forming of aluminum alloys has emerged as a prominent research topic. However, the precise mechanisms underlying the enhancement of aluminum alloy plasticity in different states remain elusive. In order to elucidate this matter, a series of uniaxial tensile experiments were conducted on Al-Mg-Si alloy featuring diverse initial states, under varying temperature conditions. The results show that when the deformation temperature is reduced from 25℃ to -196℃, the tensile strength and elongation of the wrought material are increased by 48MPa and 5.42%, and the tensile strength and elongation of the annealed material are increased by 118MPa and 5.65%. In contrast, while the T4 state sample exhibited a significant improvement in tensile strength (103MPa), no substantial enhancement in elongation was observed. This disparity can be primarily attributed to the absence of second-phase precipitation in the as-forged and annealed states. As the temperature decreased, the critical shear stress increased, resulting in increased resistance to deformation. Consequently, an increased degree of lattice rotation and activation of dislocations in various slip systems ensued, thereby improving the deformation uniformity. The formation of initial microvoids predominantly occurred close to grain boundaries. Therefore, compared with room temperature deformation, low temperature deformation caused by the accumulation of dislocations and hole sprouting concentrated at a single location was less likely. As a result, the dislocation distribution was more uniform and fracture was less likely to occur. Conversely, in the T4 state, the aging process resulted in the precipitation of a substantial amount of the soluble second phase (Mg5Si6). Consequently, microvoid nucleation transpired at the phase boundaries, leading to an elevated tensile strength. However, because of the increased dislocation hindrance when the deformation temperature was lowered, no significant enhancement in plasticity was observed.

Utilization of Butterfly Pea Flower as Shelf-Life Colour Indicator for Keropok Lekor Smart Packaging

Studying the feasibility of using Clitoria ternatea or butterfly pea extract (BPE) as a colorimetric indicator to determine the shelf life of Keropok Lekor would aid in monitoring storage conditions, emphasizing its potential contribution to the smart packaging industry. The objective of this research is to develop pH-sensitive packaging using gelatine film infused with butterfly pea extract (BPE) along with ultrasonic-assisted extraction methods. The investigation involves quantifying the physicochemical attributes of the extracted butterfly pea and ascertaining the colour alterations during the storage of Keropok Lekor over a duration of six days. The determination of total anthocyanin content in BPE, conducted through a pH differential assay, yielded a value of 1.08 mg/g. Texture analysis revealed that the film with 10% BPE exhibited elevated tensile strength (0.11±0.01) and toughness (0.03±0.01). Total phenolic compound analysis indicated that the film containing 30% BPE possessed the highest value at 0.16±0.02. Notably, the film with 30% BPE demonstrated the highest colour change in Keropok Lekor storage from dark blue (-22.5±80.95) to dark green (6.34±1.85) over the course of six days. The film incorporated with 30% BPE stands as a viable colour indicator, demonstrating the potential for monitoring the freshness and quality of Keropok Lekor.

Synthesis and properties of biodegradable PBAT prepared from PBT chemically recycled resources

The production of synthetic polymer materials has engendered substantial environmental hazards stemming from waste generation. Employing chemical recycling methods constitutes a viable approach for attaining sustained recycling of synthetic raw materials. In the present study, bishydroxybutyl terephthalate (BHBT), a precursor for the synthesis of poly(butylene adipate-co-terephthalate) (PBAT), was created by chemically alcoholyzing polybutylene terephthalate (PBT). Further, bis(4-hydroxybutyl) adipate (BHAT), which was produced via esterification with adipic acid (AA) and 1,4-butanediol (BDO), and BHBT condensation polymerization were combined to create biodegradable PBAT. Additionally, the effects of the recycled BHBT and BHAT segment ratio on the structures and properties of biodegradable PBAT were investigated. The results indicate that the synthesis of repolymerized PBAT was accomplished successfully. As the proportion of butylene terephthalate (BT) segments increased, several notable improvements were observed: an increase in melting temperature, enhanced thermal stability, elevated tensile strength, and a reduction in the rate of biodegradation. The melting point was 139.51 °C, the tensile strength was 22.62 MPa, and the 30-day biodegradation rate was 23.32 % when the percentage of BT segments was 60 %. In the present study, a method for producing biodegradable polyesters through the process of alcoholysis and repolymerization of recalcitrant polyester waste was proposed. It provides a new solution for the efficient recycling of waste polymer materials.

N‐methylmorpholine‐N‐oxide molecules coated ammonium polyphosphates for dope spinning of flame‐retardant lyocell fiber

AbstractLyocell fiber, hailed as the “verdant filament of the 21st century,” boasts elevated tensile strength, environmentally conscientious production practices, and innate biodegradability. Nonetheless, its intrinsic combustibility constitutes a noteworthy impediment to its pervasive utilization across textile and industrial domains. In a concerted effort to surmount this challenge, ammonium polyphosphate (APP) underwent modification through the infusion of N‐methylmorpholine‐N‐oxide (NMMO) molecules, amplifying its dispersibility within lyocell solutions. The resultant NMMO‐coated ammonium polyphosphate (NAPP) underwent meticulous characterization of both its structure and properties. Remarkably, lyocell fiber impregnated with 30% NAPP exhibited exemplary flame retardancy, enduring through 30 laundering cycles. Notably, its tensile strength remained notably robust at 139 MPa, demonstrating a mere 6.1% reduction in comparison to its pristine lyocell counterpart. This study delineates a promising trajectory for the fabrication of mechanically resilient lyocell fibers endowed with commendable flame‐retardant attributes.Highlights The raw material is waste cotton textiles, prepared on a green basis. The use of ultrasonic mixing and low‐speed stirring defoaming method and the use of room temperature spinning advantage of the production of flame retardant lyocell fiber. The amount of flame retardant is small, and the mechanical strength is reduced to a lesser extent. Good flame‐retardant effect and excellent water washing resistance.

Integration of nano Al2O3 and nano SiO2 in asphalt mixes: A comprehensive performance and durability evaluation

The current research work, examines efficacy of asphalt mixes prepared with varied proportions of nano SiO2 and nano Al2O3. The study assessed the performance of modified asphalt mixes through Marshall stability, flow, indirect tensile strength, resilient modulus, Dynamic modulus, Flow number, and 4-Point bending tests. Elevated nanomaterial dosages notably enhanced high and intermediate temperature performance, nearly tripling rutting resistance, and augmenting fatigue resistance by approximately 130%. Elevated tensile strength ratios confirmed improved moisture resilience. The statistical analysis showed that nanomaterials had a significant influence on properties of asphalt mixes. Overall, diverse test approaches underscored the potential of nanomaterials in enhancing asphalt mix properties, promising durable and long-lasting pavements.

The effect of 3D printing fluorene-containing poly (aryl ether ketone)/poly (ether ketone) blends on interlayer strength

The limited diffusion and entanglement of the chains between beads cause pronounced anisotropy in the mechanical properties of 3D printed parts. Therefore, amorphous poly (aryl ether ketone) (aPAEK) containing fluorene groups with high intrinsic strength and good interfacial fusion is synthesized and employed to improve the interlayer adhesion of poly (ether ether ketone) (PEEK) parts. Herein, we designed an aPAEK with high intrinsic strength and good interfacial fusion with PEEK blends. The tensile strength of 30 mol% fluorene groups aPAEK was improved to 75 MPa, and the interlayer strength of 20 wt% blends was increased by 315 % compared to PEEK. Moreover, the selection of an appropriate molecular weight for aPAEK is crucial in maintaining the elevated tensile strength while promoting interlayer diffusion during the printing process. These results highlight a novel strategy for the design and development of blend polymers for interlayer reinforcement in 3D printing applications.

Ethyl gallate isolated from phenol-enriched fraction of Caesalpinia mimosoides Lam. Promotes cutaneous wound healing: a scientific validation through bioassay-guided fractionation.

The tender shoots of Caesalpinia mimosoides Lam. are used ethnomedically by the traditional healers of Uttara Kannada district, Karnataka (India) for the treatment of wounds. The current study was aimed at exploring phenol-enriched fraction (PEF) of crude ethanol extract of tender shoots to isolate and characterize the most active bio-constituent through bioassay-guided fractionation procedure. The successive fractionation and sub-fractionation of PEF, followed by in vitro scratch wound, antimicrobial, and antioxidant activities, yielded a highly active natural antioxidant compound ethyl gallate (EG). In vitro wound healing potentiality of EG was evidenced by a significantly higher percentage of cell migration in L929 fibroblast cells (97.98 ± 0.46% at 3.81μg/ml concentration) compared to a positive control group (98.44 ± 0.36%) at the 48th hour of incubation. A significantly higher rate of wound contraction (98.72 ± 0.41%), an elevated tensile strength of the incised wound (1,154.60 ± 1.42g/mm2), and increased quantity of connective tissue elements were observed in the granulation tissues of the 1% EG ointment treated animal group on the 15th post-wounding day. The accelerated wound healing activity of 1% EG was also exhibited by histopathological examinations through Hematoxylin and Eosin, Masson's trichome, and Toluidine blue-stained sections. Significant up-regulation of enzymatic and non-enzymatic antioxidant contents (reduced glutathione, superoxide dismutase, and catalase) and down-regulation of oxidative stress marker (lipid peroxidation) clearly indicates the effective granular antioxidant activity of 1% EG in preventing oxidative damage to the skin tissues. Further, in vitro antimicrobial and antioxidant activities of EG supports the positive correlation with its enhanced wound-healing activity. Moreover, molecular docking and dynamics for 100ns revealed the stable binding of EG with cyclooxygenase-2 (-6.2kcal/mol) and matrix metalloproteinase-9 (-4.6kcal/mol) and unstable binding with tumor necrosis factor-α (-7.2kcal/mol), suggesting the potential applicability of EG in inflammation and wound treatment.

In-depth understanding of the relationship between dislocation substructure and tensile properties in a low-carbon microalloyed steel

At present, the microstructure-tensile property relationship of low carbon microalloyed steel has been widely investigated, mainly with the effects of microstructure type and its simple morphology including size and shape etc. The correlation between dislocation substructure and tensile properties, however, seems more essential and needs in-depth analysis. In this study, four typical Mn containing (from 1.08 to 1.77 wt%) low-carbon microalloyed steels were prepared by Thermo Mechanical Control Process, and the correlations among Mn content, dislocation substructure and tensile properties were investigated. A mixed microstructure consisting of polygonal ferrite, degenerated pearlite, granular bainitic ferrite and martensite/austenite (M/A) constituents formed in each steel, with highly complex dislocation configuration and distribution. For the 1.08% Mn steel, the dislocation substructures appeared mainly in dislocation wall distributing in the ferrite matrix of degenerated pearlite, and dislocation tangle in the granular bainitic ferrite around the M/A constituents and the bainitic ferrite lath boundary. As the Mn content increased from 1.45% to 1.77%, the dislocation cells appeared and increased. Simultaneously with the rising of Mn content, the mean equivalent diameter (MED) of all the ferrite matrix decreased. The ferrite grains whose MED was defined by the misorientation tolerance angles (MTAs) from 2 to 8°, featured a variety of dislocation substructures including dislocation cell boundaries, dislocation walls, bainitic ferrite lath boundaries, and dislocation tangles. They effectively governed the yield strength due to their determined close Hall–Petch relationship. Moreover, the significant increase in the amount of M/A constituents enhanced the strain hardening capacity, leading to an elevated tensile strength. Dislocation tangles exhibiting around the M/A caused a microstrain concentration, promoted additional microvoids and deteriorated the elongation.

Effect of epoxidation levels on curing characteristic and mechanical properties of ENR/MFC composites

This study aimed to investigate the effect of epoxidation levels on the curing and tensile properties of epoxidized natural rubber (ENR)/microfibrillated cellulose (MFC) composites. ENRs with different levels of epoxidation were first prepared from natural rubber (NR) latex via ‘in situ’ performic epoxidation using 0.75 M formic acid and 1 M hydrogen peroxide at 50°C at various reaction times. The results from H1 NMR revealed that the reaction at 2, 4, and 6 hours could achieve 20, 30, and 40 mol % epoxidation, respectively. The introduction of epoxide groups into NR chains reduced the scorch and cure time along with the increase of the epoxy content. Furthermore, it was observed that the tensile strength rose remarkably at 30 mol% epoxidation (ENR30). Therefore, the ENR30 was subsequently chosen to prepare the composites with various amounts of MFC (1, 3, and 5 parts per hundred rubber, phr). Interestingly, incorporating MFC elevated tensile strength and elongation at break of ENR30. At 5 phr of MFC, the composite possessed the highest tensile strength and elongation at break value, which reached up to 31.07 MPa and 922.92%, respectively.

Manufacture of all-wood sawdust-based particle board using ionic liquid-facilitated fusion process

Traditional particle board can generate harmful indoor air emissions due to the volatile resin-based compounds present. This study investigated the preparation of sawdust particle board using the novel ionic liquid based fusion approach with [EMIM]OAc. The dissolution parameters were investigated using the thermal optical microscopy technique. The particle board sheets were prepared by hot pressing sawdust in the presence of ionic liquid (IL) ([EMIM]OAc) and subsequently purifying the fusion sawdust matrix from the IL with methanol. The fusion process of the sawdust particles was analysed with SEM and mechanical testing. The raw materials and the produced materials were investigated with elemental analysis, FTIR, and 13C-SS-NMR. IL fusion of the sawdust required a temperature above 150 °C, similar to the glass transition temperature (tg) of lignin. At lower temperatures, strong particle fusion was not obtained. It was observed that the sawdust/IL weight ratio was an important parameter of the fusion process, and a 1:3 weight ratio resulted in the strongest particle boards with a tensile strength of up to 10 MPa, similar to commercial particle boards. The particle fusion process was also studied with a twin-screw extruder. The extrusion enhanced the fusion of the sawdust particles by increasing dissolution of the sawdust particles, which was subsequently seen in elevated tensile strength (20 MPa). The study provides a practical view of how sawdust-based particle board can be manufactured using ionic liquid-based fusion.

A biodegradable multifunctional nanofibrous membrane for periodontal tissue regeneration

Biomaterial-based membranes represent a promising therapeutic option for periodontal diseases. Although conventional periodontal membranes function greatly in preventing the ingrowth of both fibroblasts and epithelial cells as well as connective tissues, they are not capable of promoting periodontal tissue regeneration. Here, we report a multifunctional periodontal membrane prepared by electrospinning biodegradable polymers with magnesium oxide nanoparticles (nMgO). nMgO is a light metal-based nanoparticle with high antibacterial capacity and can be fully resorbed in the body. Our results showed that incorporating nMgO into poly(L-lactic acid) (PLA)/gelatin significantly improved the overall properties of membranes, including elevated tensile strength to maintain structural stability and adjusted degradation rate to fit the time window of periodontal regeneration. Acidic degradation products of PLA were neutralized by alkaline ions from nMgO hydrolysis, ameliorating pH microenvironment beneficial for cell proliferation. In vitro studies demonstrated considerable antibacterial and osteogenic properties of nMgO-incorporated membranes that are highly valuable for periodontal regeneration. Further investigations in a rat periodontal defect model revealed that nMgO-incorporated membranes effectively guided periodontal tissue regeneration. Taken together, our data indicate that nMgO-incorporated membranes might be a promising therapeutic option for periodontal regeneration. Statement of SignificanceTraditional clinical treatments of periodontal diseases largely focus on the management of the pathologic processes, which cannot effectively regenerate the lost periodontal tissue. GTR, a classic method for periodontal regeneration, has shown promise in clinical practice. However, the current membranes might not fully fulfill the criteria of ideal membranes. Here, we report bioabsorbable nMgO-incorporated nanofibrous membranes prepared by electrospinning to provide an alternative for the clinical practice of GTR. The membranes not only function greatly as physical barriers but also exhibit high antibacterial and osteoinductive properties. We therefore believe that this study will inspire more practice work on the development of effective GTR membranes for periodontal regeneration.

Effects of Parenteral Amino Acid Administration on the Postoperative Nutritional Status and Wound Healing of Protein-Malnourished Rats

In Japan, parenteral nutrition (PN) solutions are frequently administered to patients in the postoperative short-term period. In these cases, amino acid-containing peripheral parenteral nutrition (PPN) solutions, amino acid-free maintenance solutions or combinations of the two are used. However, consensus regarding the most beneficial solution for these patients is lacking. Here, we examined the nutritional status and wound healing outcomes in protein-malnourished rats receiving postoperative administrations of PPN solution, maintenance solution or combinations of the two solutions. Protein malnutrition was induced in Sprague-Dawley rats by feeding an AIN-93G-based low-protein diet (5% casein) for 2 wk. After laparotomy, dorsal skin incision, and placement of a jugular vein catheter, the rats were divided into 3 groups. Each group was administered 113 kcal/kg/d, with group A receiving maintenance solutions without amino acid, group B receiving PPN with 1.5% amino acid, and group C receiving PPN with 3% amino acid. After 5 d post-operative administration, we measured the tensile strength of the wound area, skeletal muscle weights, and nutritional parameters. Significantly higher plasma nutritional parameters and gastrocnemius and extensor digitorum longus (EDL) muscle weights were observed in groups B and C than in group A. Group C exhibited significantly elevated tensile strength of the wound area along with up-regulation of type I collagen mRNA expression compared to group A. These findings demonstrate the nutritional status and wound healing benefits of short-term postoperative administration of PPN solutions containing amino acids in protein-malnourished rats.

Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition.

Plants mainly utilize inorganic forms of nitrogen (N), such as nitrate (NO3–) and ammonium (NH4+). However, the composition of the N source is important, because excess of NH4+ promotes morphological disorders. Plants cultured on NH4+ as the sole N source exhibit serious growth inhibition, commonly referred to as “ammonium toxicity syndrome.” NH4+-mediated suppression of growth may be attributable to both repression of cell elongation and reduction of cell division. The precondition for cell enlargement is the expansion of the cell wall, which requires the loosening of the cell wall polymers. Therefore, to understand how NH4+ nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH4+ as the sole N source has smaller cells with relatively thicker cell walls. Moreover, cellulose, which is the main load-bearing polysaccharide revealed a denser assembly of microfibrils. Consequently, the leaf blade tissue showed elevated tensile strength and indicated higher cell wall stiffness. These changes might be related to changes in polysaccharide and ion content of cell walls. Further, NH4+ toxicity was associated with altered activities of cell wall modifying proteins. The lower activity and/or expression of pectin hydrolyzing enzymes and expansins might limit cell wall expansion. Additionally, the higher activity of cell wall peroxidases can lead to higher cross-linking of cell wall polymers. Overall, the NH4+-mediated inhibition of growth is related to a more rigid cell wall structure, which limits expansion of cells. The changes in cell wall composition were also indicated by decreased expression of Feronia, a receptor-like kinase involved in the control of cell wall extension.

Characterization of surimi slurries and their films derived from myofibrillar proteins with different extraction methods

Abstract Characteristics of surimi slurries and their films made from fish myofibrillar protein were investigated. Films made from fish protein slurries consisting of Alaska pollock surimi (15% and 20%) and sodium chloride (0%, 2%, and 5%) were either adjusted to different pH (7, 9, and 11) or mixed with sodium tripolyphosphate (STP) (1.0%, 1.5%, and 2.0%). Increasing pH from 7 to 9 led to higher viscosity and exposed sulfhydryl sites, while further pH increase 9–11) reduced the viscosity values and surface reactive sulfhydryl groups. NaCl and STP addition decreased slurry viscosity. In most treatments involving the roles of pH and either sodium chloride or sodium tripolyphosphate in film formation, sodium chloride addition contributed to lower puncture strength and puncture distance. Meanwhile, there was a tendency for elevated tensile strength and reduced elongation at break as sodium chloride concentration was increased from 0% to 5%. Shifting pH to a more basic condition contributed to higher puncture strength and distance. As STP concentration in the surimi slurries increased up to 2%, puncture and tensile strength increased, but puncture distance and elongation at break decreased.

Effect of increased N content on microstructure and tensile properties of low-C V-microalloyed steels

The processing of four low-carbon vanadium-microalloyed steels with varying nitrogen (N) content of 30–165ppm, including preheating at 1200°C, rapid cooling to 550°C for isothermal transformation, and air cooling, was simulated using a Gleeble 3500 system. The microstructure of each sample was characterized and the tensile properties measured; a microstructure consisting of granular bainitic ferrite (GBF), acicular ferrite (AF), and martensite/austenite (M/A) constituent formed in all of the samples. Moreover, the increasing N content led to an increase in the effective grain size of the GBF and AF and a decrease in the density of dislocations, as well as promoted the precipitation of nanoscale particles; however, the overall yield strength decreased slightly. The increased N content also resulted in an increased amount of M/A constituent, which improved the overall strain-hardening capacity of the microstructure of GBF+AF/M/A, and resulted in an elevated tensile strength and a simultaneously lowered yield-to-tensile strength ratio. In addition, the mechanisms governing the effect of increased N in controlling the final microstructure and tensile properties were discussed.

Conserved C-Terminal Domain of Spider Tubuliform Spidroin 1 Contributes to Extensibility in Synthetic Fibers

Spider silk is renowned for its extraordinary mechanical properties, having a balance of high tensile strength and extensibility. To date, the majority of studies have focused on the production of dragline silks from synthetic spider silk gene products. Here we report the first mechanical analysis of synthetic egg case silk fibers spun from the Latrodectus hesperus tubuliform silk proteins, TuSp1 and ECP-2. We provide evidence that recombinant ECP-2 proteins can be spun into fibers that display mechanical properties similar to other synthetic spider silks. We also demonstrate that silks spun from recombinant thioredoxin-TuSp1 fusion proteins that contain the conserved C-terminal domain exhibit increased extensibility and toughness when compared to the identical fibers spun from fusion proteins lacking the C-terminus. Mechanical analyses reveal that the properties of synthetic tubuliform silks can be modulated by altering the postspin draw ratios of the fibers. Fibers subject to increased draw ratios showed elevated tensile strength and decreased extensibility but maintained constant toughness. Wide-angle X-ray diffraction studies indicate that postdrawn fibers containing the C-terminal domain of TuSp1 have more amorphous content when compared to fibers lacking the C-terminus. Taken together, these studies demonstrate that recombinant tubuliform spidroins that contain the conserved C-terminal domain with embedded protein tags can be effectively spun into fibers, resulting in similar tensile strength but increased extensibility relative to nontagged recombinant dragline silk proteins spun from equivalently sized proteins.

120 放電プラズマ焼結法によるTiAl焼結体の引張特性(粉末成形とその評価)

Spark Plasma Sintering (SPS) can consolidate compacts at lower sintering temperature and in shorter sintering duration compared with conventional sinterings, such as hot-pressing or HIP. TiAl (Ti-48at%Al) compacts were sintered with changing sintering temperature and sintering duration. From tensile properties, the most suitable sintering condition of TiAl by SPS was investigated. And elevated tensile strength was also investigated.

Cu nanowhiskers embedded in Nb nanotubes inside a multiscale Cu matrix: The way to reach extreme mechanical properties in high strength conductors

For the development of high pulsed magnets, reinforced Cu/Nb/Cu conductors composed of a multiscale Cu matrix embedding Nb nanotubes were produced by severe plastic deformation. While the Nb nanotubes exhibit a rather homogeneous microstructure with maximum grain size of 100 nm and 〈1 1 0〉 texture, a complex microstructure was pointed out in the Cu matrix with bimodal grain size distribution and duplex texture (〈1 1 1〉 and 〈2 0 0〉 orientations). The Cu/Nb/Cu system is also characterized by elevated tensile strength that follows a modified rule of mixture. The Cu nanofilaments inside Nb nanotubes behave as nanowhiskers.

The physicodynamic properties of mucoadhesive polymeric films developed as female controlled drug delivery system

To develop an efficient female controlled drug delivery system (FcDDS) against sexually transmitted diseases (STDs), the polymeric films containing sodium dodecyl sulfate (SDS) were prepared with various compositions of Carbopol 934P, hydroxypropyl methylcellulose (HPMC) and polyethylene glycol (PEG). The physicochemical properties of mucoadhesive polymeric films, such as tensile strength, contact angle, swelling ratio and erosion rate in a vaginal fluid stimulant (VFS), were characterized. In addition, the drug release profile of SDS from the films and mucosal residence time were evaluated using a simulated dynamic vaginal system. It was demonstrated that the films made of Carbopol, HPMC and PEG were colorless, thin and soft and had proper physicodynamic properties for FcDDS. An increase in Carbopol content elevated tensile strength and swelling ratio but decreased the contact angle, erosion rate and the SDS release rate from the films. The films containing 0.25% (w/v) PEG as well as 0.75% (w/v) of combining Carbopol and HPMC remained on the vaginal tissue for up to 6 h. The films containing the ratio of Carbopol:HPMC:PEG = 1.5:1.5:1 and 1:2:1 seem to be optimal compositions for FcDDS, as they showed good peelability, relatively high swelling index and moderate tensile strength, and achieved the target release rate of SDS for 6 h.

Mechanical Properties and Creep Behavior of Mg–Al–Ca Alloys

This paper investigates the microstructure, mechanical properties and creep behavior of Mg–Al–Ca alloys with different Ca content. SEM and EDAX analyses show that the dominant second phase in the as-cast Mg–Al–Ca alloys is Al2Ca, which distributes at the grain boundaries and disperses in the grain interior as well. Both the elevated tensile strength and the creep resistance of Mg–Al–Ca alloys obviously increased with increasing Ca at high temperature. TEM analyses reveal that finer Al2Ca particles with an average size of 0.02 µm precipitated dynamically during the creep process. Selected area electron diffraction (SAD) patterns show that the dynamic Al2Ca precipitates have a coherent interface with matrix as (0110) Mg // (220) Al2Ca, [2110] Mg // [112] Al2Ca. The strengthening mechanism of Mg–Al–Ca alloys at elevated temperature was discussed.