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This work aims to determine the Kearns texture parameters and evaluate on their basis the elastic moduli, mechanical properties (ultimate tensile strength, conditional yield stress), as well as damageability parameters of the sheets commercial titanium (CT-grade 1: 0.04% Fe; 0.015% C; 0.05% N 0.05% c; 0.009% H) as delivered after rolling and annealing at 840°C (original sheet) and further alternating bending (AB) in the amount of 0.5; 1, 3 and 5 cycles. Damageability parameters characterizing damage accumulation were determined from the elastic modulus change after the above-mentioned number of AB cycles relative to the values ​​of the elastic modulus in different directions of the original sheet of the studied titanium. The elastic constants of the single crystal and the Kearns texture parameters were used to estimate the elastic modulus in the rolling direction (RD) and transverse direction (TD) of the original sheet, and sheets after an above number of AB cycles. The deviation of the calculated and experimental values ​​of the elastic modulus did not exceed 5%. The deviation of the calculated and experimental values of the ultimate tensile strength and yield stress in the RD and TD both in the initial state and after the corresponding number cycles of the AB did not exceed 10%.

Statement of problem: Changing the internal design of a metal framework may decrease the manufacturing time, the weight of the restoration, and the amount of alloy powder used, as well as simplify the fabrication process. Purpose: The purpose of this in vitro study was to evaluate the effect of framework internal design changes on the mechanical properties of cobalt-chromium (Co-Cr) specimens manufactured by using direct metal laser sintering (DMLS). Material and methods: Dumbbell-shaped test specimens were designed as per the International Organization for Standardization (ISO) 22674(E) standard by using a 3-dimensional software program. A total of 70 dumbbell-shaped specimens were prepared by using Co-Cr alloy powder and DMLS (n=10). The control group specimens were solid with the internal completely filled. For the test groups, the internal design of the dumbbell-shaped specimens was modified. Leaving the outer shell thickness of the specimens at 0.5 mm for all test groups, 6 different internal designs were created, and the specimens were weighed. The tensile strength test was used to evaluate the mean peak strength, elastic modulus, and percentage elongation of the specimens. One-way ANOVA followed by the Dunnett T3 test was used for statistical analysis (α=.05). Results: A statistically significant difference was found among the groups in terms of bar weight and peak strength (P.05). Conclusions: Decreasing the weight of the frameworks by changing the internal design of the specimens also decreased the peak strength. However, it did not affect the elastic modulus or the percentage of elongation.

Poly (decamethylene terephthalamide/decamethylene isophthalamide)-block-polyvinyl alcoho) (PA10T/10I-PEG) copolymer/graphene oxide (GO) composites were prepared via in-situ melt polymerization and two different nano-filler addition approaches were compared. The relationship between the micro-structure and performance of the elastomer composites prepared by one-step and two-step methods was explored. The results show that the two-step method significantly promoted the dispersion of the GO in a polymer matrix, and facilitated the grafting of more hard molecular chains. Thus, the elastic modulus and tensile strength of the nano-composite have been significantly improved by the presence of GO. This was because of the strong interaction between the functional groups on the surface of the GO and the hard molecular chains. This would be also be favorable to load transfer across the interface. Additionally, the elongation at the break of composites increased by 10% with the addition of a small amount of GO (0.2% wt). This is because hard domains tend to be enriched on the surface of GO in composites and act as a lubricating layer at the interface between the GO and matrix, leading to increased deformation ability. This work provides an effective strategy to prepare elastomer composites with high strength and toughness.

In order to improve the wettability and bonding performance of the interface between carbon fiber and aluminum matrix, nickel- and copper-coated carbon fiber-reinforced aluminum matrix composites were fabricated by the squeeze melt infiltration technique. The interface wettability, microstructure and mechanical properties of the composites were compared and investigated. Compared with the uncoated fiber-reinforced aluminum matrix composite, the microstructure analysis indicated that the coatings significantly improved the wettability and effectively inhibited the interface reaction between carbon fiber and aluminum matrix during the process. Under the same processing condition, aluminum melt was easy to infiltrate into the copper-coated fiber bundles. Furthermore, the inhibited interface reaction was more conducive to maintain the original strength of fiber and improve the fiber–matrix interface bonding performance. The mechanical properties were evaluated by uniaxial tensile test. The yield strength, ultimate tensile strength and elastic modulus of the copper-coated carbon fiber-reinforced aluminum matrix composite were about 124 MPa, 140 MPa and 82 GPa, respectively. In the case of nickel-coated carbon fiber-reinforced aluminum matrix composite, the yield strength, ultimate tensile strength and elastic modulus were about 60 MPa, 70 MPa and 79 GPa, respectively. The excellent mechanical properties for copper-coated fiber-reinforced composites are attributed to better compactness of the matrix and better fiber–matrix interface bonding, which favor the load transfer ability from aluminam matrix to carbon fiber under the loading state, giving full play to the bearing role of carbon fiber.

The failure mechanisms of Oxide-Oxide ceramic matrix composites AS-N610 were studied at both room temperature and high temperature using tensile and fatigue tests with and without lateral and laminar notches. The unnotched coupons had an average tensile strength of 423 MPa with elastic modulus of 97 GPa at room temperature showing a perfect elastic behaviour whereas the laminar notched samples shown similar strength of 425 MPa with elastic modulus (98 GPa) revealing pseudo-ductile behaviour. A reduction in tensile strength of the oxide ceramic matrix composites was observed at high temperatures. Thermal shock experiments revealed that the retained strength of the samples quenched from 1100 °C deteriorated by ∼10 % (395 ± 15 MPa). In all samples fracture origin was observed on the mid plane showing a higher degree of fiber pull-out, delamination and pseudo ductile behaviour. FEA confirmed higher stress concentration on the areas of failures.

Purpose: To compare the mechanical properties and fracture behaviour of laser-sintered/3D-printed cobalt chromium (LS CoCr) with soft-milled cobalt chromium (SM CoCr) to assess their suitability for use in high-stress areas in the oral cavity. Material and Method: Two computer-aided manufacturing methods were used to fabricate dumbbell specimens in accordance with the ASTM standard E8. Specimens were fractured using tensile testing and elastic modulus, and proof stress and ultimate tensile strength were calculated. Fracture surfaces were examined using scanning electron microscopy. Plate specimens were also fabricated for the examination of hardness and elastic modulus using nanoindentation. Unpaired t-test was used to evaluate statistical significance. Results: LS CoCr specimens were found to have significantly higher ultimate tensile strength (UTS) and proof stress (PS) (p &lt, 0.05) but not a significantly higher elastic modulus (p &gt, 0.05). Examination of the dumbbell fracture surfaces showed uniform structure for the LS CoCr specimens whilst the SM CoCr specimens were perforated with porosities, neither showed an obvious point of fracture. Nanoindentation also showed that LS CoCr specimens possessed higher hardness compared with SM CoCr specimens. Conclusion: LS CoCr and SM CoCr specimens were both found to exhibit uniformly dense structure, although porosities were noted in the SM CoCr specimens. LS CoCr specimens were found to have superior tensile properties, likely due to lack of porosities, however both had mean values higher than those reported in the literature for cast CoCr. Uniformity of structure and high tensile strength indicates that LS CoCr and SM CoCr fabricated alloys are suitable for long-span metallic frameworks for use in the field of prosthodontics.

In this work, biocomposites based polylactic acid (PLA) filled with piper betle fiber (PBF) were successfully synthesized by solvent cast-film method using chloroform as the solvent. The PBF was treated with 7% NaOH. The biocomposites were loaded separately with untreated and treated PBF at 1 to 3 wt% and investigated for tensile properties and morphological of fractured surfaces. Tensile strength and modulus elasticity of biocomposites were increased with addition of betel particles and found to be higher than the matrix. Furthermore, the alkali treatment of PBF had considerably improved tensile and modulus of biocomposites compared to those of biocomposites with untreated PBF. A contrary trend was found in the case of elongation at break. However, biocomposites with treated PBF had greater elongation compared to those of biocomposites with untreated PBF. These results were identified by fracture examination with scanning electron microscopy (SEM). SEM observations showed the good bonds formed between treated PBF and PLA. This indicated by less cavity and roughness on biocomposite fractured surface with treated PBF.

Bacterial cellulose (BC) membranes are an excellent ecopolymer product that has been proposed for many applications, including acoustic, biomedical, and fabrics. However, those uses require the membranes’ exposure to environmental conditions related to shelf storage, washing, or excess of humidity that are not usually evaluated when developing new materials. In this work, we investigated the effect of high and low temperature, and high humidity accelerated exposure on the physical and mechanical properties of BC membranes prepared from Kombucha fermentation. We prepared BC membranes following standard protocols and subjected them to a composite temperature/humidity accelerated cyclic assay. The mechanical and physical properties of the membranes were measured before and after the assay. We found that the ultimate tensile strength, elastic modulus, and elongation at break significantly changed after the assay. We also observed a few morphology changes, but no changes in the DSC and IR determinations. Our results suggest that environmental tests should be performed in every biodegradable polymer according to their intended use to determine their applications fully.

Purpose The aim of this study was to analyze the effects of 10-minute (standard term) versus 20-minute treatment with glutaraldehyde (GA) on mechanical stability and physical strength of human pericardium in the setting of the OZAKI procedure. Methods Leftover pericardium (6 patients) was bisected directly after the operation, and one-half was further fixed for 10 additional minutes. Uniaxial tensile tests were performed and ultimate tensile strength (UTS), ultimate tensile strain (uts), and collagen elastic modulus were evaluated. Results Both treatments resulted in similar values of uniaxial stretching-generated elongations at rupture (10 minutes 25 ± 7 % vs. 20 minutes: 22 ± 5 %; p = 0.05), UTS (5.16 ± 2 MPa vs. 6.54 ± 3 MPa; p = 0.59), and collagen fiber stiffness (elastic modulus: 31.80 ± 15.05 MPa vs. 37.35 ± 15.78 MPa; p = 0.25). Conclusion Prolongation of the fixation time of autologous pericardium has no significant effect on its mechanical stability; thus, extending the intraoperative treatment cannot be recommended.

Anisotropy of mechanical properties of the entire material and each of its layers is characteristic for polymer layered composite materials, as well as the fact that production processes of the composite material and parts from it are often combined in time. In this case, the elastic properties and strength of the material will be different not only in the thickness of the part, but also at each point. All this leads to a complication of the design process, which is due to the need to determine the elastic properties and strength of the polymer layered composite materials, taking into account the structure of the entire material and each of its layers. This work aims at evaluating the existing computational methods of finding effective characteristics of elastic properties by comparing computation results obtained by various methods with each other, as well as with the experimental results related to elastic properties of polymer layered composite materials from carbon and glass fabrics. We estimated the computational methods of finding effective characteristics of the elastic properties of composites based on the experimental results of finding the characteristics of the elastic properties of polymer layered composite materials made of carbon and glass fabrics, differing in density and type of weaving. The experimental values of the effective characteristics of elastic properties were determined as a result of standard tensile tests of laboratory specimens. As a result of the study, it was found that all the considered models and methods give consistent results when calculating the longitudinal modulus of elasticity E 11, the results of calculating shear modulus E 33 and shear moduli G 12 and G 23 are less consistent for all the considered materials. The comparison of the results of the experimental studies and computations showed that the Chamis model and the bridge model are better than other models to predict the values of the longitudinal elastic modulus.

Recently, glass fiber reinforced polypropylene is commonly used in scientific and industrial applications such as marine, aerospace, automotive, and construction industries among other materials because of their low cost, lightweight, easy processing, and high reliability. For those promising characteristics, researches have been undertaken for understanding the thermal and mechanical behaviors of polypropylene. The main objective of this study is to investigate the mechanical properties of polypropylene (PP) and glass fiber reinforced polypropylene (GFPP) pipes, which are used in water distribution networks and compressed air systems. Tensile tests were performed at different cross-head speeds at room temperature while, flexural tests were conducted at different cross-head speeds with five distinct temperatures 23, 35, 50, 70, and 90 °C. The experimental results show that both materials are sensitive to cross-head speed, temperature, and holding time. Additionally, the percentage of elongation at break and toughness of GFPP are lower than that of PP. However, the elastic modulus and yield stress of GFPP are higher than that of PP at the same cross-head speed. On the other hand, the bending energy and the dissipated energy of GFPP are higher than that of PP under all cross-head speeds and testing temperatures. PP gains 20.4% and GFPP gains 15.2% bending energy with raising cross-head speed from 5 to 50 mm/min. Also, a decrease in flexural modulus for both materials occurs with raising temperature from 23 to 50 °C.

Particulate Nano Aluminum Hybrid Composites (PNAHC) are prepared by the combined effect of stir casting with ultrasonic process. PNAHC is prepared by reinforcing 3% by weight of rice husk char (RHC) and with varying weight percentages of TiC such as: 3%, 6%, 9% and 12%. The effect of the reinforcements on the PNAHC is studied by tensile, compressive, bending, impact, microhardness and density. Halpin-Tsai and the rule of mixing equations serve to measure the elastic modulus and the Poisson ratio. The formation of Al12Mg17 as an intermediate element and other key elements such as Aluminium, TiC and SiO2 are consistent with the XRD technique. The homogeneous dispersal of the reinforcements is verified using the SEM model with EDS. Microstructural arrangements of the reinforcements and its behavior on test load conditions under casting process with and without ultrasonic-assisted stir casting where compared and reported.

Environmentally friendly plastics can be degraded biologically in an anaerobic environment. This plastic is synthesized from starch such as sago starch which is available in abundance. In the form of bioplastics, its mechanical properties are still not compared to conventional plastics derived from crude oil, so its application is limited. The incorporation of filler material increases its mechanical properties, one of the selected fillers is hemp fiber as used in this study. Thermoplastic starch from sago with flax fiber as a filler and the addition of Polypropylene to improve mechanical properties with a certain composition to maintain its natural biodegradability. The mechanical properties analyzed were tensile strength, elongation and modulus of elasticity. Water absorption tests were also carried out to observe the water resistance properties. The results of the tensile strength test showed that the best tensile strength value of 9.32 Mpa was obtained at the addition of 35% fiber with a TPS: PP ratio of 1:1.5. The same conditions were obtained for the percent elongation with the results of 10.16% and the modulus of elasticity was 91.73 Mpa. Water absorption showed that 55% filler gave the lowest water absorption, namely 4.41% at a ratio of TPS: PP 1:0.5. The addition of fiber filler into the bio-composite affects the tensile strength, elongation and modulus of elasticity, the higher the volume of filler entering the bio-composite, the lower the value of tensile strength, elongation and modulus of elasticity, or vice versa. The ratio of addition of polypropylene matrix is also influential, the higher the ratio contributes to the tensile strength, elongation and higher modulus of elasticity. High water absorption capacity will reduce the performance of biocomposite, so the lower the water absorption ability, the better the quality of the biocomposite product and the wider its application

A simplified and green strategy was provided for the synthesis of cellulose acetate. Cellulose acetate (CA) was isolated from the directly acetylated eucalyptus powder after hydrothermal treatment to selectively remove hemicellulose without delignification. The conversion rate of cellulose (90.75%) and the yield of the acetylated product (61.34%) were greatly improved by hydrothermal treatment, while the re-condensation of lignin during hydrothermal treatment made no adverse difference. The characterization results verified that the acetylated product was cellulose acetate with uniform molecular weight, good thermal stability and semi-crystalline structure. Moreover, CA was used to reinforce polylactic acid (PLA) films prepared by solvent casting. The PLA-CA composite with 5 wt% CA showed an increase of 80.63% in tensile strength and 59.51% in Young's modulus, and their density decreased from 1.2427 g/cm3 to 1.0028 g/cm3. The lightweight and excellent mechanical properties promote the application potential of biodegradable composites to replace petroleum-based plastics.

The advocacy of carbon neutrality and circular economy encourages people to pursue self-healing and recycling of glassy thermoset polymers in a more realistic and energy-saving manner, the best being intrinsic healing under room temperature. However, the high mechanical robustness and healing ability are mutually exclusive because of their completely opposite requirements for the mobility of the polymer networks. Here, we report a dual-cross-linked network by slightly coupling the low-molecular-weight branched polyethylenimine with an ester-containing epoxy monomer in a nonstoichiometric proportion. The highly mobile and dense noncovalent hydrogen bonds at the chain branches and ends can not only complement the mechanical robustness (tensile strength of 61.6 MPa, elastic modulus of 1.6 GPa, and toughness of 19.2 MJ/m3) but also endow the glassy thermoset polymer (Tg > 40 °C) with intrinsic self-healing ability (healing efficiency > 84%) at 20 °C. Moreover, the resultant covalent adaptive network makes the thermoset polymer stable to high temperatures and solvents, yet it is readily dissolved in ethylene glycol through internal catalyzed transesterification. The application to room temperature delamination healing and carbon fiber recycling was demonstrated as a proof-of-concept.

In this study, a novel biopolymer based on poly(glycerol sebacic)-urethane (PGS-U) and its nanocomposites containing Cloisite@30B were synthesized by facile approach in which the crosslinking was created by aliphatic hexamethylene diisocyanate (HDI) at room temperature and 80 °C. Moreover, metronidazole and tetracycline drugs were selected as target drugs and loaded into PGSU based nanocomposites. A uniform and continuous microstructure with smooth surface is observed in the case of pristine PGS-U sample. The continuity of microstructure is observed in the case of all bionanocomposites. XRD result confirmed an intercalated morphology for PGSU containing 5 wt% of clay nanoparticles with a d-spacing 3.4 nm. The increment of nanoclay content up to 5%, the ultimate tensile stress and elastic modulus were obtained nearly 0.32 and 0.83 MPa, which the latter was more than eight-fold than that of pristine PGS-U. A sustained release for both dugs was observed by 200 h. The slowest and controlled drug release rate was determined in the case of PGSU containing 5 wt% clay and cured at 80 °C. A non-Fickian diffusion can be concluded in the case of tetracycline release via PGS-U/nanoclay bionanocomposites, while a Fickian process was detected in the case of metronidazole release by PGS-U/nanoclay bionanocomposites. As a result, the designed scaffold showed high flexibility, which makes it an appropriate option for utilization in the treatment of periodontal disease.

3D-printed samples of carbon fiber–reinforced acrylonitrile butadiene styrene (CF-ABS) are exposed to radiation doses of up to 15 kGy with a Cobalt-60 gamma irradiator. The effects of irradiation, the choice of material (CF-ABS or ABS), and the order of fabrication (before or after irradiation) are examined. CF-ABS has a smaller ultimate tensile strength and a larger elastic modulus than ABS alone regardless of the radiation dose or the order of printing. At zero dose, flexural moduli for CF-ABS are 66% larger than those in ABS. Several properties of CF-ABS show almost a 20% decrease after 1 kGy of irradiation when it is printed with pre-irradiated filament, which does not occur in ABS or when CF-ABS samples are printed prior to irradiation.

This work presents an investigation on the morphology, mechanical, viscoelastic and transport properties of acrylonitrile–butadiene–styrene (ABS) nanocomposites reinforced with nanosilica (NS) and multiwalled carbon nanotubes (MWCNTs). The nanofillers content was varied from 1 to 5 wt%. Morphological and mechanical investigations revealed a better dispersion and effective stress transfer in carboxyl-treated MWCNT composites with respect to silane-treated NS. The highest values of tensile strength and Young’s modulus were reached for 5 wt% of MWCNT. Theoretical modelling of elastic modulus of the composites with carbon nanotubes (CNT) was in good agreement with experimental data. On the other hand, in the case of composites with NS an interfacial modulus of 2.5 GPa was assumed in the model to approach the experimental data. The highest value of storage modulus was reported at a MWCNT content of 5 wt% followed by 3 wt% which discloses the stiffening effect of long curly CNTs in comparison with NS. The damping behaviour indicated a lowering and broadening of tan δ peak induced by CNT. The storage modulus and damping behaviour of the nanocomposites were analysed using theoretical models in which aspect ratio, stiffening effect, adhesion and entanglement phenomena were included. The lowest solvent diffusivity and permeability was exhibited by composite with MWCNT at 5 wt% owing to the tortuosity, higher adhesion and aspect ratio of the filler and revealed a decrement in permeability by 62% with regard to neat ABS.

The present study aims at investigating the effect of organic-modified nickel phyllosilicate (NiPS) particles on the structure–property relationships of epoxy (EP) composites. The organic-modified NiPS particles were synthesized using a facile sol–gel method and subsequently mixed into EP matrix by physical blending to improve its tribological, mechanical and thermal properties. Based on a series of tests and analyses, it was found that organic-modified NiPS particles playing a great role in improving the tribological properties under dry sliding. The steady-state friction coefficient was just decreased moderately, whereas the wear rate was dropped significantly to 0.36 × 10−5 mm3/N·m, showing a reduction up to ca. 95% in comparison with pure EP. According to the analysis of worn surfaces, the main mechanism of wear resistance was discussed. The elastic modulus for the EP composites was increased remarkably while the elongation at break decreased. However, the added organic-modified NiPS particles show a negligible influence on the tensile strength. Moreover, the incorporated NiPS particles could enhance the thermal stability of EP composites, showing the notably suppressed mass loss rate and added residual chars. This study provided a promising way for preparing the high-performance EP composites with organic-modified lamellar particles.

The influence of NO2 concentration and exposure time on the degradation of polyphenylene sulfide (PPS) fabric filter at high temperature was investigated in detail. PPS fiber damage in the filter became more severe with increasing NO2 concentration and exposure time. The elastic modulus of the PPS filter increased rapidly during the initial stage of exposure, and then increased more slowly to reach an almost constant value, nearly independent of NO2 concentration. The tensile strength also decreased significantly during the initial stage, gradually attaining a constant value with increasing exposure time. Higher NO2 concentrations resulted in rapid reducing of the tensile strength. Short exposure time to lower NO2 concentrations caused the oxidation of S atoms in PPS to SO and O S O, whereas oxidation of benzene rings in PPS were induced only with longer exposure times and higher NO2 concentrations. The model proposed in our previous paper accurately expresses the change in PPS conversion and reaction rate for every NO2 concentration. An improved model that successfully estimated the degradation of tensile strength in both the machine direction and transverse direction, regardless of NO2 concentration, was also proposed.

Continuous graphene fibers (GFs) and graphene/SiC fibers (G/SiCFs) are fabricated from silicon carbide (SiC) fibers through vacuum annealing. The transformation gradually happens from the surface to the core of the fiber until complete conversion. Graphene sheets are in-situ formed after Si sublimation of 3C–SiC grains in the SiC fiber. Although porous structure is formed inevitably, the fiber shape is well maintained with circular cross section. The continuous GFs exhibit low density (1.63 g/cm3), excellent electric conductivity (53,900 S/m), high tensile strength (0.22 GPa) and elastic modulus (23 GPa, gauge length: 25 mm). Good properties can be probably attributed to interconnected graphene sheets. GFs have great electromagnetic interference shielding effectiveness of 62.8 dB, while G/SiCFs have outstanding microwave absorption properties. The minimum reflection loss (RL) value of −54.86 dB is achieved with sample thickness of 2.1 mm. When sample thickness is 1.4 mm, the effective absorption bandwidth of G/SiCFs can reach 4.4 GHz. Excellent flexibility is also possessed by a bundle of 1000 graphene filaments. Taking advantages of the facile conversion of silicon carbide fibers, the method demonstrated in this work can be further extended to prepare metal-containing GFs (Ti, Al, Zr, et.) and achieve large-scale production.

Polyvinyl alcohol (PVA) hydrogels with excellent characteristics are considered as promising cartilage replacement materials. However, there are still some main issues to be solved for PVA hydrogel, such as poor mechanical strength and disordered structure. Inspired by the highly ordered structure of biological soft tissues such as articular cartilage, here, we prepared a high-strength but anisotropic polyvinyl alcohol-nanohydroxyapatite-polyacrylic acid (PVA-HA-PAA) composite hydrogel by directional stretching, freezing–thawing, and annealing method. Stretching of an as-prepared isotropic PVA-HA-PAA composite hydrogel leads to the orientation of PVA crystallites and PVA chains, which enables the formation of ordered structure and more hydrogen bonds via freezing under stretching. The microstructure, water content, swelling and creep performance, tensile and bio-tribology properties of the composite hydrogel are studied, the results indicated that the properties of the hydrogel are affected by stretching due to the formation of ordered structure in the anisotropic hydrogel. For instance, the elastic modulus and tensile strength of the anisotropic hydrogel reach 5.703 MPa and 18.958 MPa, respectively, which is significantly enhanced by comparing with isotropic hydrogel. Moreover, the friction property is anisotropic, and the Coefficient Of Friction (COF) reduced in the parallel direction. Thus, this work provides a simple and practicable strategy to design strong and anisotropic hydrogels for potential applications in biomedical materials such as cartilage substitute.

The properties of butylene succinate ternary copolymers containing aliphatic diols and dicarboxylic acids in an amount of 5 and 10 mol % as a third comonomer are studied. The copolymers have reduced strength characteristics compared to poly(butylene succinate). The heat of fusion, the glass transition temperature, the elastic modulus, the yield point, and the tensile strength of the copolymers decrease slightly with an increase in the weight content of third comonomer units. Stretching of copolymers during strength testing does not lead to their strain hardening. The degradation rate of copolymers in wet soil increases by 1.5–3.0 times relative to the rate of degradation of poly(butylene succinate) and grows with an increase in the proportion of the third comonomer.

The effects of bio-based strengthening agents and mineral filling procedure on the 3D elongation of chemi-thermomechanical pulp (CTMP) handsheets with and without mineral (PCC) filling have been investigated. The 3D elongation was measured using a press-forming machine equipped with a special converting tool. The strength of the handsheets was altered using either cationic starch or microfibrillated cellulose. Precipitated calcium carbonate (PCC) was added to the furnish either as a slurry or by precipitation of nano-sized PCC onto and into the CTMP fibre. The 3D elongation of unfilled sheets was increased by the dry-strengthening agents, but no evidence on the theorised positive effect of mineral fill on 3D elongation was seen in either filling method. The performance of the strengthening agent depended on whether the PCC was as slurry or as a precipitated PCC-CTMP. The starch was more effective with PCC-CTMP than when the PCC was added directly as a slurry to the furnish, whereas the opposite was observed with microfibrillated cellulose. The 3D elongation correlated positively with the tensile strength, bursting strength, tensile stiffness, elastic modulus and bending stiffness, even when the sheet composition was varied, but neither the strengthening agent nor the method of PCC addition affected the 3D elongation beyond what was expectable based on the tensile strength of the sheets. Finally, mechanisms affecting the properties that correlated with the 3D elongation are discussed.

The nanocomposites of flower-like nickel phyllosilicate particles incorporated into epoxy resin were fabricated via an in-situ mixing process. The flower-like nickel phyllosilicate particles were firstly synthesized using a mild self-sacrificial templating method, and the morphology and lamellar structure were examined carefully. Several properties of mechanical, thermal and tribological responses of epoxy nanocomposites were performed. It was demonstrated that adequate flower-like nickel phyllosilicate particles dispersed well in the matrix, and the nanocomposites displayed enhanced tensile strength and elastic modulus but decreased elongation at break as expected. In addition, friction coefficient and wear rate were increased first and then decreased along with the particle content, and showed the lowest values at a mass fraction of 5%. Nevertheless, the incorporated flower-like nickel phyllosilicate particles resulted in the continuously increasing thermal stability of epoxy resin (EP) nanocomposites. This study revealed the giant potential of flower-like particles in preparing high-quality EP nanocomposites.

Additive manufacturing incorporates the utilization of polymers with additives to print 3D specimens in layers. FDM (fused deposition modelling) technique in AM (additive manufacturing) has gained much attention in recent years because of its ability to make complex shapes with great design flexibility. To explore the possibilities with new design pattern specimens with various percent infills is the need of the hour. This paper presents an investigation on the tensile properties of ABS, PLA, and CF (15% by weight fraction) reinforced with PLA specimens. Herein, to print the specimen, a newly triangular pattern is used in the gauge length with different infill percentages oriented at 0°, 45°, and 90°. The motivation is to understand the role of a pattern on mechanical properties. The analysis revealed that the reduction in percent strength corresponding to percent material removed from a particular infill is much less than expected. Thus fabricating a part in a specific pattern may lead to material saving and cost reduction. Besides, printing orientation also played a significant role in determining the ultimate strength. 0° orientation for maximum cases led to the highest strength, whereas 45° was the poorest printing orientation. As expected all the properties got enhanced with increasing infill percentages. Findings in line with the previous work revealed PLA + CF with the highest tensile strength while ABS has the least strength. PLA exhibited the largest Elastic modulus among the three materials. The SEM images in fracture morphology of the specimens indicated the bonding between the CF with PLA and failed layers.

The effects of various physical state lipids (rapeseed oil (RO), shortening (ST), beeswax (BW)), on the physicochemical properties of starch (S) (hydroxypropyl distarch phosphate (HP), oxidized hydroxypropyl starch (OS))/gelatin (G) blown films were studied. S/G-lipid blends showed decreased storage modulus and complex viscosity. The formation of hydrogen bonds was inhibited by the ST and BW, but facilitated by the RO. Compared with BW and ST, RO was more effective to promote the melted and fractured of starch. Lipids addition promoted the compatibility of starch and gelatin. The presence of the lipids significantly improved the surface hydrophobicity, mechanical, water vapor barrier and water resistance properties of S/G films. S/G-RO films exhibited the strongest surface hydrophobicity and tensile strength, while HP/G-BW film showed the strongest water resistance and water vapor barrier properties. These results revealed that the appropriate lipids could be used to produce S/G-lipid films with desirable physicochemical properties.

The understanding of compressive and tensile behaviors of polypropylene fiber-reinforced cemented paste backfill (FR-CPB) play crucial roles in the successful implementation of reinforcement technique in underground mine backfilling operations. However, very limited studies have been performed to gain insight into the evolution of compressive and tensile behaviors and associated mechanical properties of FR-CPB under various curing temperatures from early to advanced ages. Thus, this study aims to investigate the time (7, 28, and 90 d)- and temperature (20°C, 35°C, and 45°C)-dependence of constitutive behavior and mechanical properties of FR-CPB. The obtained results show that pre- and post-failure behaviors of FR-CPB demonstrate strongly curing temperature-dependence from early to advanced ages. Moreover, the pseudo-hardening behavior is sensitive to curing temperature, especially at early ages. Furthermore, the mechanical properties including elastic modulus, material stiffness, strengths, brittleness, cohesion, and internal friction angle of FR-CPB show increasing trends with curing temperature as curing time elapses. Additionally, a predictive model is developed to capture the strong correlation between compressive and tensile strength of FR-CPB. The findings of this study will contribute to the successful implementation of FR-CPB technology.

Tough adhesives with robust adhesion are desperately needed for biomedical and technological applications. However, it is extremely challenging to engineer tough and durable adhesives that are simple to make yet also exhibit strong underwater adhesion as well as tough bonding to diverse surfaces. Here, we report bioinspired elastomers based on water-immiscible polydiolcitrates, where their tough mechanical properties, robust underwater adhesion (80 kPa), and tough bonding performance (with an interfacial toughness >1000 J m-2 and a shear and tensile strength >0.5 MPa) to diverse solid materials (glass, ceramics, and steel) are actuated by the incorporation of trace amounts of additives. The additives could edit the polymer networks during the elastomer polymerization by dramatically regulating the cross-linking structures of covalent and reversible bonds, the length of polymer chains, and the hydrophobic and hydrophilic motifs, which markedly tuned the mechanical and adhesive properties of the bioelastomers. We also demonstrate versatile applications of the durable elastomers, as tough flexible joints for solid materials, superglue, tissue sealants, hemostatic dressing, and wound repair.

Based on the promising biomedical developments in wound healing strategies, herein, a new nanobiocomposite scaffold was designed and presented by incorporation of carboxymethyl cellulose hydrogels prepared using epichlorohydrin as a cross-linking agent (CMC hydrogel), a natural silk fibroin (SF) protein, and magnesium hydroxide nanoparticles (Mg(OH)2 NPs). Biological evaluation of the CMC hydrogel/SF/Mg(OH)2 nanobiocomposite scaffold was conducted via in vitro cell viability assays and in vivo assays, red blood cell hemolysis, and antibiofilm assays. Considering the cell viability percentage of Hu02 cells (84.5%) in the presence of the prepared nanobiocomposite after 7 days, it was indicated that this new nanoscaffold was biocompatible. The signs of excellent hemocompatibility and the high antibacterial activity were observed due to the low-point hemolytic effect (8.3%) and high-level potential in constraining the P. aeruginosa biofilm formation with a low OD value (0.13). Moreover, in vivo wound healing assay results indicated that the wound healing method was faster in mice treated with the prepared nanobiocomposite scaffold (82.29%) than the control group (75.63%) in 12 days. Apart from the structural characterization of the CMC hydrogel/SF/Mg(OH)2 nanobiocomposite through FTIR, EDX, FESEM, and TG analyses, compressive mechanical tests, contact angle, porosity, and swelling ratio studies indicated that the combination of the CMC hydrogel structure with SF protein and Mg(OH)2 NPs could significantly impact Young's modulus (from 11.34 to 10.14 MPa), tensile strength (from 299.35 to 250.78 MPa), elongation at break (12.52 to 12.84%), hydrophilicity, and water uptake capacity (92.5%).

A new type of imitation rattan was developed via a two-step method that used modified wheat straw as the raw materials and low-density polyethylene to make up wood plastic composite. Post-modification, a graft condensation reaction was carried out between silane as a coupling agent and wheat straw powder, which improved the thermal stability of the composite. A high level of contact and interaction at the fibre-matrix interface was observed. The optimum formula for the first step was 80% wheat straw powder, 4% silane coupling agent, and 16% calcium carbonate, with a modification temperature of 120 °C sustained for 10 min. For the second step, the mechanical properties had been greatly improved with the addition of modified wheat straw fibre and maleic anhydride grafted polypropylene (MA-g-PP). The use of 10% modified straw fibre and 5% MA-g-PP exhibited the highest tensile strength (8.75 MPa) and highest melt index (2.86 g/10 min). In particular, the MA-g-PP had an extremely advantage to the elastic modulus of wheat straw imitation rattan. The elastic modulus reached the maximum value of 2761.70 MPa at the amount of MA-g-PP added reached 5%. Our present study indicated the innovation of a new type of imitation rattan, which provides a new choice for utilizing wheat straw as industrial raw material, and other agricultural by-products containing liginocellulose could be used in a similar way.

Orevac–crumb rubber–arabinogalactan composites of different composition are obtained under the action of shear deformations in a Brabender mixer. The structure, mechanical properties, and biodegradability of the materials are studied. It is shown that an increase in arabinogalactan content leads to increase in elastic modulus and decrease in elongation at break, as well as slightly affecting the tensile strength. The mass loss of the samples after exposure in soil defining their biodegradability rises with an increase in arabinogalactan content in the composites.

The objective of this study was to prepare, for the first time, active films and coatings from fruit starch (SPFS) and phenolic stem bark extract (SBPE) from Spondias purpurea L. Starch film formulations were prepared with different SBPE contents (5–20 wt% on starch), then cast and dried into films. SBPE showed higher antioxidant activity and antimicrobial activity against both Gram-negative and Gram-positive bacteria. Chemical, morphological, thermal, optical, mechanical, and barrier properties were studied for SPFS-SBPE films. In general, the phenolic extract caused significant changes in starch films (especially when in excess), such as gradual reduction of elastic modulus and tensile strength, increased elongation, opacity, and thermal properties (e.g. glass transition and melting enthalpy). On the other hand, SBPE provided the films with active properties (antioxidant and UV-absorbing). Coatings were applied to minimally processed mangoes (MPM), which were stored for 10 days at 12 °C. SBPE-containing coatings provided better protective action, reducing the total color difference (∆E⁎) and delaying the browning index (BI) during storage as well as reducing fungus attack. The active SPFS-SBPE films showed great potential as environmentally friendly active films and coatings.

The starch-based film development has been extensively studied since, in general, it is possible to obtain transparent, non-toxic, odorless, good gas barrier, biodegradable, and tasteless samples. However, world hunger-related problems are a reality and the use of starches, a recognized carbohydrate source, in the packaging industry should be avoided. Thus, the use of different residual starchy can minimize the costs of production, promoting the development of innovative biomaterials, eliminating the competition with the food chain. The objective of the present work was to evaluate the impact of the cassava starch (CS) substitution by gelatinized starch (GS), a residue generated in the sieving step of starch processing, verifying possible changes in the final material characteristics. The raw materials characterization includes determination of amylose and moisture contents, centesimal composition, particle size distribution, and thermal analysis. After casting solution and drying processes, the samples were evaluated regarding the visual macroscopic and microscopic aspects showing continuous and homogeneous structure. The results were related to the physicochemical and mechanical properties. The GS addition promoted a decrease in the tensile strength (3.3 ± 0.1 MPa to 1.2 ± 0.3 MPa) and elastic modulus (52 ± 13 MPa to 10 ± 3 MPa) values, while the elongation percentage (160 ± 30% to 212 ± 14%) values seem to have not been so affected. It can be seen a high potential for the use of agro-industrial residues containing starch in bioplastic production.

Fused deposition modeling (FDM) has been the preferred technology in 3D printing due to its ability to build functional complex geometry parts. The lack of the printing parameter information and prediction model that directly reflects towards 3D printed part's mechanical properties has been a barrier for the FDM 3D printer users to appraise the product's strength as a whole. In the present work, 27 tensile specimens with different parameter combinations were printed using a low-cost FDM 3D printer according to the ASTM standard to evaluate their tensile properties. Statistical analysis was performed using MINITAB to validate the experimental data and model development. The investigational outcomes reveal that ultimate tensile strength was primarily affected by infill density, whereby it increases with increasing infill density. Elastic modulus, fracture strain, and toughness were mainly affected by infill density and layer thickness. The ideal printing parameter for optimal tensile behavior was identified to be 0.3 mm layer height, 40° raster angle, and 80% infill density from the 9th combination. The tensile values obtained for the optimal printing parameter were 28.45150 MPa for ultimate tensile strength, 0.08012 mm/mm for fracture strain, 828.06000 MPa for elastic modulus, 20.19923 MPa for yield strength, and 1.72182 J/m3 for toughness. The statistical analysis further affirmed the optimum printing has a minimal deviation from the experimental response. Finally, a mathematical model is proposed for the tensile properties prediction.

This research explores intrinsic properties of the carbon-rich subsurface zone (“case”) that low-temperature carburization generates in an austenitic stainless steel (AISI-316). Foils of this steel were carburized to obtain concentrated interstitially dissolved carbon distributed uniformly throughout their thickness. Compared to the as-received foils, such “through” carburization increases the ultimate tensile strength to 3 times, the yield strength to 4 times, and Young's modulus to 1.5 times, respectively. On the other hand, the strain to failure decreases to (9 ± 1) × 10−3. For comparison, foils with larger thickness were carburized as well. Those foils retained a core of low carbon level. Decreasing the ratio of mean carbon depth to foil thickness was found to decrease the ultimate tensile strength, the yield strength, and Young's modulus, while increasing the strain to failure. Tensile testing partially carburized foils to failure confirmed ductility in the core, but revealed reduced ductility in the carbon-rich zone near the surface. On the surface, intergranular cracks were observed to propagate perpendicular to the tensile direction, indicating brittle fracture initiated by crack nucleation at grain boundaries. The isolated concentrated solid solution of interstitial carbon in austenite can be regarded as a new material with exceptional properties, particularly ultrahigh tensile strength, high yield strength, and high Young's modulus.

Cadmium oxide doped zinc oxide (CdO–ZnO) nanoparticles were synthesized by solution combustion technique. CdO–ZnO nano particles were used as fillers and their concentration ranged between 0.5% to 2.5% by weight in polyvinyl alcohol (PVA) films. The effect of nano filler concentration on structural, electrical and mechanical properties was investigated. Dielectric constant values decreased upto 1.24 GHz frequency, between 1.24 to 3 GHz frequency range a slight increase in dielectric constant was observed. At frequencies above 500 kHz increase in AC conductivity and loss tangent of the polymer nanocomposites were observed. Enhanced mechanical properties were observed with increase in dopant concentration. A significant increase of 152.65% in film toughness, 113.58% increase in elastic modulus and 83.10% increase in ultimate tensile strength was observed at 2.5 wt% concentration of CdO–ZnO in PVA film as compared to pristine PVA film, which makes CdO–ZnO a desirable reinforcing material for nanocomposites.

The present work focuses on determination of the mechanical properties of paraffin-based hybrid rocket fuels. The tensile tests were performed to evaluate the ultimate tensile strength, elastic modulus and percentage elongation at break. Three classes of paraffin-based fuels such as Paraffin/Polyethylene (P/PE), Paraffin/Polyethylene/Boron (P/PE/B) and Paraffin/Polyethylene/Aluminum (P/PE/Al) were prepared with and without Stearic acid (SA). The tensile tests were performed as per ASTM standard. The paraffin sample was used as the reference. The ultimate tensile strength of the P/PE formulation increased from 14% to 39%with the increase of PE loading from 5wt.% to 15wt.% and the elastic modulus was found to increase from 114.36 MPa to 129.27 MPa. Furthermore, the addition of SA also contributed to the increase of tensile strength and elastic modulus for P/PE formulations. For the P/PE formulation, the addition of B enhanced the tensile strength from 32.7% to 47.13% with the loading of B content increased from 5wt.% to 25wt.%. The paper discusses about the effect of additives on the formulation and the optimal loading ratio without compromising on the regression factor.

Purpose The purpose of this study is to explore the use of silver submicron-scale wire (AgSMW) additives in filament feedstock for fused filament fabrication (FFF) additive manufacturing technologies. The antibacterial effect of the additive on printed objects is assessed and its impact on mechanical behavior is determined. Design/methodology/approach AgSMW-PLA composite FFF filaments were fabricated by solution processing, granulation and extrusion. The reduction in the growth of Escherichia coli (E. coli) is measured after exposure to FFF-printed composite test specimens with AgSMW additive concentrations ranging from 0.0 to 10.0 weight per cent. The effect of the additive addition on the thermal properties and tensile mechanical performance was measured. Scanning electron microscopy (SEM) was used to analyze the composite microstructure and fracture behavior. Findings E. coli growth was reduced by approximately 50 per cent at the highest additive concentration of 10.0 weight per cent. This is attributed to the release of silver ions through water diffusion into the bulk of the composite. The ultimate tensile strength declined with increasing AgSMW concentration with a moderate reduction of 18 per cent at 10.0 weight per cent. The elastic modulus did not vary significantly at any of the concentrations studied. The ductility of the composite was only notably reduced at the highest concentration. The reduction in mechanical strength and strain at break is attributed to an increase in void defects in the composite with increasing additive concentration. Originality/value This study demonstrates the successful incorporation of AgSMWs into FFF-compatible filaments for use in commercially available printing systems. The results demonstrate significant reduction of bacteria growth when using these materials. While the mechanical performance degrades slightly, the results indicate the material’s efficacy for a variety of potential biomedical applications. As a proof of concept, surgical tools were printed using the composite.

Current synthetic vascular grafts are not suitable for use in low-diameter applications. Silk fibroin is a promising natural graft material which may be an effective alternative. In this study, we compared two electrospun silk grafts with different manufacturing processes, using either water or hexafluoroisopropanol (HFIP) as solvent. This resulted in markedly different Young’s modulus, ultimate tensile strength and burst pressure, with HFIP spun grafts observed to have thicker fibres, and greater stiffness and strength relative to water spun. Assessment in a rat abdominal aorta grafting model showed significantly faster endothelialisation of the HFIP spun graft relative to water spun. Neointimal hyperplasia in the HFIP graft also stabilised significantly earlier, correlated with an earlier SMC phenotype switch from synthetic to contractile, increasing extracellular matrix protein density. An initial examination of the macrophage response showed that HFIP spun conduits promoted an anti-inflammatory M2 phenotype at early timepoints while reducing the pro-inflammatory M1 phenotype relative to water spun grafts. These observations demonstrate the important role of the manufacturing process and physical graft properties in determining the physiological response. Our study is the first to comprehensively study these differences for silk in a long-term rodent model.

Two methods are commonly used to disperse graphene nanoplatelets (GNPs) in a polymer matrix system (PMS) — microcompounding and ultrasonication. In this work, GNPs-PMS nanocomposite specimens of different weight ratios were first produced using microcompounding. Results of tensile tests showed that, on introduction of 0.5 wt.% GNPs into the PMS, its ultimate tensile strength (UTS) increased by 15% and the elastic modulus by 11%. Based on these results, 0.5 wt.% GNPs were also used in producing specimens by the ultrasonication technique, which showed a 69% drop in the UTS and a 227% increase in the elastic modulus. These findings demonstrate that the mechanical properties of GNPs-PMS nanocomposites are highly sensitive to their manufacturing method.

The present work demonstrates the relationship between the tensile and hardness properties, crystalline structure as well as rheological behavior and gel content for the organo-montmorillonite (OMMT) filled poly(ethylene-co-vinyl acetate) (EVA)/acrylonitrile-butadiene rubber (NBR) nanocomposites. The NBR/EVA mixtures containing 5% (wt) OMMT were first provided and then cured with 0–2% (wt) dicumyl peroxide. The results of tensile experiments showed that while the elastic modulus and yield stress linearly increased, strain-at-break linearly decreased with gel content in the range studied. It was also found that the tensile strength and modulus at 100 and 300% strain increased exponentially, however, energy-at-break decreased in the form similar to an inverse S-shaped curve with gel content. The Cole–Cole plots revealed that the relaxation time increased progressively with the increase in gel content. Wide-angle X-ray diffractometry showed that the peak intensity ratio of I110/I200 was reduced by the addition of OMMT and increased somewhat with increasing in gel content. In addition, the Casson plot was employed to calculate the yield stress of the materials. The results indicated that the yield stress of the uncured nanocomoposite was higher than that of the simple blend and the value progressively increased with the increase in gel content.

This study investigates the effect of Nano-zinc oxide on tensile properties of natural rubber composites by replacing the conventional zinc oxide by Nano-zinc oxide as an activator. It has a small particle size and large surface area in comparison with conventional zinc oxide. In this paper, one compound has a conventional zinc oxide as an activator with concentration 8phr (part per hundred rubber) and eight compounds have Nano-zinc oxide as an activator with concentrations (0.2, 0.6, 1, 1.4, 1.8, 2.2, 2.6, 4) phr. The tensile test sample carried out by using the Monsanto T10 Tensometer. Results show that maximum values of tensile strength and elastic modulus at 300% are found with Nano-zinc oxide at 1.8 phr. Replacing the conventional zinc oxide by Nano-zinc oxide decreases the price of the compounds due to reducing the amount of zinc oxide inside the compounds by 77.5%. It also reduces the contamination of the environment and improves the tensile strength by 38.31%. http://dx.doi.org/10.30572/2018/kje/090105

Eco‐friendly composite materials have received more attention in recent years, and research has shown that biostructures have great potential as a solution to meet the needs of sustainability in product design and potential food packaging. In this study, the mechanical, thermal, morphological, water absorption properties and water vapor permeability of bio‐composites based on polyethylene and sour cherry shell powder (SCS) (0% –7.5%) have been investigated. It was observed that 2.5% of sour cherry shell increased elastic modulus and tensile strength and improved mechanical properties. Composites without adding sour cherry shell show 1.28% water absorption. Decreased water absorption was observed for treated composites containing 2.5% of sour cherry shell, and its amount was 1.26%. The presence of sour cherry shell increased the bio‐composite resistance to moisture absorption, but the addition had little effect on the thermal process properties of polyethylene. Vapor permeability in sour cherry shell / polyethylene bio‐composites, which was a significant difference between samples with sour cherry shells (2.5%–7.5%) and samples without sour cherry shells. Results indicated that polyethylene/sour cherry shell composites could be used to replace polyethylene in application such as stretch film, shrink film, and bags of fruit., Polyethylene/sour cherry shell bio‐composites could be used to replace polyethylene in application such as stretch film, shrink film and bags of fruit. valorization of fruits waste and increasing biodegradability and environmental issues was the objectives of this research.

In this study, the advantages and disadvantages of different titanium alloys used as industrial and biomedical implant materials are evaluated within the scope of multiple parameters. This research is supported by simulations and aims to understand how titanium and titanium alloys differ mechanically, micro-structurally and in terms of radioactivity. The matrix material of the eight samples used in this research is titanium. The effects of different elements such as Al, V, Sn, Ni, Pb, Mo, Cr, Zr, Fe, Nb, Co on titanium have been examined, the results are compared by considering multiple parameters, and the superior properties of the prominent alloys are highlighted. As a result of the mechanical and electrical tests performed on the alloys, it is obvious that the titanium alloy consisting of Mo and Nb has the highest Brinell hardness, elastic modulus, tensile strength and electrical conductivity parameters compared to other alloys examined within the scope of this research. In the metallographic studies and analyses on samples made up of different alloys, different structures and images emerge for each alloy. These elements rapidly lower the solidification temperature of the material, allowing the β phase to be formed. It has been observed that the two-phase situation has positive effects on the material. On the other hand, the results of gamma ray attenuation tests reveal that Mo and Nb, which make up the alloy, have superior performance compared to other alloy samples due to their high atomic number.

Cellulose nanofibrils (CNFs) can be used as an effective reinforcement material for biopolymer films intended for food packaging applications. The aim of this study was to improve the mechanical and barrier properties of xylan-alginate films by incorporating CNFs into the xylan-alginate matrix. CNFs was produced from maize stalk waste residues through a combination of chemical and mechanical treatment. The CNFs was incorporated into the xylan-alginate matrix between 1 and 10 wt%. The suitability of the CNFs reinforced composite films for food packaging applications was investigated by testing the mechanical, thermal and optical properties as well as the moisture sorption, solubility and water vapour permeability of the films. The CNFs produced had fibre diameters between 10 and 80 nm and transmission electron microscopy images showed that the CNFs were highly entangled hence forming a web like structure. It was found that the incorporation of CNFs into the xylan-alginate matrix increased the tensile strength and Young's modulus of the films. The incorporation of CNFs improved the WVP of the films but did not show any significant effect on the thermal properties of the films.

Among the natural fibers, the hemp fiber extracted from the stem of Cannabis sativa is, after sisal, the second most applied as reinforcement of polymer composites and increasingly used from automotive to civil construction industries. Polypropylene (PP) is the most common hemp fiber-reinforced matrix. Despite numerous papers on the application of natural fibers reinforcing polymer composites for ballistic protection, only one was so far dedicated to hemp fibers/PP with this purpose. In the present work, the main objective is for the first time to investigate the ballistic performance of the epoxy matrix reinforced with up to 30 vol% of hemp fabric. Epoxy is recently emerging as another strong alternative for the hemp fiber/fabric matrix. Due to the great variability in properties, a preliminary investigation was conducted on the basic mechanical and thermal behavior of the composites. The 30 vol% reinforcement with hemp fabric increased by 7.5 times the Izod impact energy as well as by more than 60% the tensile strength and 80% of the elastic modulus as compared to the neat epoxy. For all composites, a decrease of 20% in thermal temperatures (Tonset and Tmax) occurred in comparison to neat epoxy. The absorbed ballistic energy from the impact of 0.22 ammunition was significantly higher (95–108.5 J) than that previously reported of 36 J for hemp fabric/PP composite and others natural fiber/epoxy composites.

Automobile airbags have become mandatory safety components in many countries. In this study, the PA66 (polyamide 66) airbag fabric was tested with and without a surface coating of PVC (polyvinyl chloride). Cyclic loading and unloading experimental conditions were defined according to the loading characteristics of the airbag deployment process. To determine mechanical properties such as elastic modulus and stress-strain curves for the two materials, biaxial loading/unloading cyclic tensile tests were carried out using a DIC (Digital Inspection Camera) to monitor the field strain process. Quadratic polynomial regression was used to fit material constitutive models of each loading and unloading process to the test data. The material subroutine VUMAT was encoded and applied to the simulation of the biaxial tensile testing of the fabrics. There was good agreement between the experimental and simulation results, which verifies that the quadratic polynomial constitutive material model is suitable for the study of coated and uncoated PA66 automobile airbag fabric. Hence, the material behaviour of automobile airbag fabrics can be modelled accurately.

Chitin-based bio-composites in nature such as the exoskeleton of crustaceans and squid pen usually exhibit hierarchical structures, where the chitin crystal is the most fundamental structural hierarchy as the load-bearing scaffold. Previous studies have unveiled the mechanical design of the structures at high hierarchies in these biomaterials, while the structure–property relationship remains unclear for the chitin crystal at the bottom hierarchy. In this paper, we investigate the mechanical properties of chitin crystals with $$\alpha$$ - and $$\beta$$ -polymorphic structures that mainly exist over the animal kingdom using the reactive force field molecular dynamics simulations. We first validate the force field parameters adopted from literature then study the mechanical behaviors of chitin polymorphs in response to the tensile and shear deformation. It is found that the mechanical performance of $$\alpha$$ -chitin crystal is comprehensively superior to that of $$\beta$$ -chitin crystal, such as the elastic modulus, work of fracture, shear modulus and strength. Different from the $$\beta$$ -chitin, yielding caused by the transformation of crystalline structure is observed in the $$\alpha$$ -chitin during uniaxial tension. Based on the mechanical properties obtained from simulations and theoretical analysis, we can deduce that the $$\alpha$$ -chitin shows higher wear resistance than the $$\beta$$ -chitin, implying better protection against the surface scratch that is one of the environmental threats to organisms. Our results shed light on the structure–property relationship of chitin crystals at the molecular level. The fundamental understanding of mechanical properties of chitin polymorphs is of great significance for the bottom-up modeling and design of chitin-based bio-composites.

Inspired by the delicate architecture of hyaline articular cartilage, we report on a biomimetic polymer hydrogel that incorporates strong intermolecular hydrogen bonding between urethane–urethane linkages as well as urethane–ester linkages. The resultant hydrogel, containing ≈75% water, can endure a compressive stress up to 56 MPa with a strain of 98%, and exhibit tunable compressive modulus (0.19–1.38 MPa), as well as toughness (3629–28290 J m–2) within a wide range. The tensile strength and elastic modulus reach as high as 0.56 and 5.5 MPa, respectively. The high stiffness and toughness enable the gel to withstand cyclic compressive loadings without fracturing. Moreover, our hydrogel mimics the extracellular matrices of cartilage and bone tissues and provides biochemical and physical cues that support the three-dimensional proliferation of chondrocytes and osteogenic differentiation of preosteoblasts.