Reduction In Tensile Strength Research Articles

The effect of Xylocaine spray on suture material degradation.

To compare the tensile strength of fast absorbable Polyglactin 910 suture material when impregnated with various agents for local anesthesia and to investigate whether the presence of ethanol in Xylocaine spray could explain a potential reduction in tensile strength after use of Xylocaine spray. In all, 120 suture samples of Polyglactin 910 were divided into four groups of 30. These four groups were randomly impregnated with isotonic sodium chloride, isotonic sodium chloride plus Xylocaine spray, isotonic sodium chloride plus Xylocaine gel, or isotonic sodium chloride plus ethanol. After impregnation, the sutures were stored in sealed glass tubes in a heating cabinet at 37°C for 72 h. Thereafter, the tensile strength of these 120 samples was assessed by a universal tensile testing machine. The maximal force needed to break the suture material was recorded in newtons (N). Fast absorbable Polyglactin 910 suture material impregnated with Xylocaine spray or ethanol showed weakened tensile strength (mean values 11.40 and 11.86 N, respectively), whereas the specimens impregnated with Xylocaine gel or sodium chloride retained their tensile strength better (mean values 13.81 and 13.28 N, respectively; mean difference between Xylocaine gel and Xylocaine spray -2.41 N, P < 0.001). In this invitro experiment, ethanol and Xylocaine spray weakened the tensile strength of fast absorbable Polyglactin 910 sutures. Use of Xylocaine spray, which contains ethanol, for local anesthesia might lead to early breakdown of the suture material and wound rupture. The authors suggest caution when using Xylocaine spray in combination with fast absorbable Polyglactin 910 suture.

Mechanical Property Characterization of Architectural Coated Woven Fabrics Subjected to Freeze–Thaw Cycles

This paper presents experimental investigations into the freeze–thaw response of two common architectural coated woven fabrics. Strip specimens for the tensile tests were exposed to −20 °C for three hours followed by three hours of thaw at ambient temperatures. This was repeated for a maximum of 100 cycles. Afterwards, the residual tensile strength was measured and compared to results achieved for test specimens without prior freeze–thaw cycles. Maximum mean tensile strength reductions of approximately 21% (warp direction) and 19% (weft direction) for probed polytetrafluoroethylene (PTFE)-coated woven glass fiber fabrics were identified, while no remarkable tensile strength deterioration rate was observed for the investigated polyvinyl chloride-coated woven polyethylene terephthalate materials. Overall, the results indicate that freeze–thaw cycles can have a significant deteriorating impact on the mechanical properties of glass-PTFE fabrics.

Microstructure Formation and Its Effect on Mechanical Properties for Duplex Stainless Steel 2205 Plasma Arc Welded Joint

The control of phase balance has always been a tough challenge for the welding of duplex stainless steel, which heavily restricts its optimal serving performance in engineering. The microstructure development and mechanical characteristics of SAF2205 plasma arc welded joints were thoroughly examined in this paper. It was proven that the phase balance can be well controlled by plasma arc welding, and the austenite content of the welded joints was about 60%. Despite successful phase control, there was still grain coarsening and distortion; i.e., at the center of the welded zone, the gain size was about eight times that of the base metal, and the austenite was mainly in the form of grain boundary austenite and intragranular austenite, while more Widmanstatten austenites were found in the heat-affected zone. In addition, a transition region between the heat affected zone and the center exhibited columnar ferritic grains. Furthermore, the plasticity and toughness of the welded joints were significantly decreased, especially the elongation in the longitudinal direction, which is about 10% lower than that of the base metal, and transversal tensile strength remained comparable to the base metal, with only a slight reduction in longitudinal tensile strength. Lastly, the formation mechanism of microstructure and its correlation with mechanical properties were revealed. This investigation offers valuable insights into the structural integrity of duplex stainless steel welded joints in engineering applications.

Stochastic finite element modeling of heterogeneities in massive concrete and reinforced concrete structures

AbstractThe lifespan of a reinforced concrete (RC) structure can be greatly influenced by the spatial variability of its material characteristics which, in particular, explains the observed or measured reduction of the tensile strength at first crack when the volume under tension increases. This paper discusses the ability of accounting for the spatial variability of the tensile strength of concrete in RC structures using a stochastic finite element (SFE) method based on random field simulations. In this work, the generation of random fields on the concrete tensile strength aims at computing the force corresponding to the first crack occurrence, and the reduced tensile strength of the structure. The method can be applied in particular to large‐sized structures, which show a pronounced size effect, for different types of loading. The method consists of, first, estimating the mean of the random field, using the analytical approach of the weakest link and localization method (WL ). Then, the discretized random field is defined on a particular 2D or 3D grid, and it is finally projected on the finite element mesh of the studied structure. The study of the parameters that influence the prediction of the cumulative density functions (CDFs) of the rupture force or the tensile strength is highlighted using experimental series of concrete beams having different volumes and subjected to 4‐point bending loading. Moreover, the SFE method is applied to a RC tie‐beam under tensile loading, characterized by a weak stress gradient, which complicates the prediction of crack positions.

Enhancing the dynamic mechanical properties of thermoplastic elastomers: A study on polypropylene /natural rubber blends

The aim of this study was to investigate the modifications of the mechanical properties of polypropylene (PP) by incorporating elastomers, while considering the impact on its stiffness. Specifically, the research focused on determining the optimal loading of elastomer to achieve desirable properties and exploring the influence of these processes on the morphology and mechanical behavior of the prepared blends. Thermoplastic elastomers (TPEs) consisting of polypropylene and natural rubber (PP/NR) were prepared using a melt-mixing process, and the mechanical properties of the blends were evaluated. The stress-strain properties of the blends revealed a successful modification of PP, transforming it from a stiff and strong thermoplastic into a stiff and tough thermoplastic elastomer when 10% NR was included in the PP matrix. As the loading of NR increased, a reduction in tensile strength (TS) and modulus (E) of the blends was observed, while elongation at break (EB) increased. The flexural strength of unmodified PP was 45.9 MPa, which decreased with increasing NR loading. Similarly, the impact strength of unmodified PP was 25.8 KJ/m2, whereas the values for 10%, 20%, 30%, and 40% NR inclusion were 30.8, 24.3, 20.6, and 15.2 KJ/m2, respectively. The melt flow index (MFI) of unmodified PP was 14.1 g/10 min, while the values for 10%, 20%, 30%, and 40% NR inclusion were 19.4, 15.7, 11.6, and 10.2 g/10 min, respectively. The best combination of mechanical properties was observed at 10% NR inclusion in the PP matrix. The micrograph of the blends, as observed from SEM micrographs, supported the modification of PP, resulting in the production of TPE with observable adhesion sites, indicating good compatibility between the components. In a nutshell, a significant 47% increase in impact strength was achieved through the modification process.

Lignin-derivable, thermoplastic, non-isocyanate polyurethanes with increased hydrogen-bonding content and toughness vs. petroleum-derived analogues.

The functionality inherent in lignin-derivable bisguaiacols/bissyringols can improve the processability and performance of the resulting polymers. Herein, non-isocyanate polyurethanes (NIPUs) were synthesized from bisguaiacols/bissyringols with varying degrees of methoxy substitution and differing bridging groups. Notably, the presence of increasing numbers of methoxy groups (0, 2, and 4) in bisphenol F (BPF)-, bisguaiacol F (BGF)-, and bissyringol F (BSF)-NIPUs led to higher percentages of hydrogen-bonded -OH/-NH groups (i.e., ∼65%, ∼85%, ∼95%, respectively). Increased hydrogen bonding between chains improved the elongation-at-break (εbreak) and toughness of lignin-derivable NIPUs over their petroleum counterparts without a reduction in Young's moduli and tensile strengths. For example, BSF-NIPU exhibited the highest εbreak ∼210% and toughness ∼62 MJ m-3, followed by BGF-NIPU (εbreak ∼185% and toughness ∼58 MJ m-3), and then BPF-NIPU (εbreak ∼140% and toughness ∼42 MJ m-3). Similar trends were found in the dimethyl-substituted analogues, particularly for the bisphenol A-NIPU and bisguaiacol A-NIPU. Importantly, the melt rheology of the lignin-derivable NIPUs was comparable to that of the petroleum-derived analogues, with a slightly lower viscosity (i.e., improved melt flow) for the bio-derivable NIPUs. These findings suggested that the added functionalities (methoxy groups) derived from lignin precursors improved thermomechanical stability while also offering increased processability. Altogether, the structure-property-processing relationships described in this work can help facilitate the development of sustainable, performance-advantaged polymers.

Re-use of polyamide-12 in powder bed fusion and its effect on process-relevant powder characteristics and final part properties

Powder bed fusion (PBF) is an additive manufacturing technique capable of fabricating highly complex, individualised, and lightweight polymer components. However, to maximise the potential of PBF, in terms of both economic efficiency and environmental sustainability, a successful powder re-use strategy is essential. During a build, ageing and degradation processes affect the re-usability of un-sintered powder, so used powder is usually refreshed with virgin material before re-use. This study considers the effectiveness of using a 70:30 refresh ratio in a specific PBF technique: laser sintering (LS). Across a total of seven printing cycles, polyamide-12 (PA-12) powder refreshed with 30 % virgin material after each build, revealed a 4.5 °C increase in melting temperature. There was also a 20 % reduction in particle flowability, which may be related to the presence of fine satellite particles and considerable particle cracking. This deterioration in powder quality resulted in a 5.8 % increase in total part porosity, and an 11 % reduction in the ultimate tensile strength of fabricated parts, over the seven build cycles. A Pearson correlation test indicated that the reduction in powder flowability was the most significant (p-value of 0.005) cause for the loss of part strength; emphasising that the revolution powder analyser could be a useful complimentary technique for determining the quality of used powder within laser sintering. Nonetheless, compared to previous studies which re-used 100 % aged PA-12 powder, without refreshing with any virgin material, the observed reduction in part strength is relatively modest. This suggests that a 70:30 refresh ratio offers a good compromise between maintaining part performance, particularly for non-critical applications, without having to add an unnecessary amount of virgin powder. Therefore, this study reveals the relationship between the deterioration of powder properties and reductions in part strength; yet highlights the benefits of operating with a 70:30 refresh ratio when re-using PA-12 powder across multiple build cycles.

Evaluating Combination of Solvent-Based Recycling and Mechanical Recycling of ABS Materials for Mitigating Plastic Pollution and Promoting Environmental Consciousness

Plastics continue to transform everyday life with their versatility, lightweight, and durability, although the escalating issue of plastic pollution necessitates urgent action. The surge in single-use plastics and a disposable culture worsens this problem, emphasizing the need to reduce plastic production, establish circular material models, and phase out single-use plastic products.&#x0D; Addressing the environmental impact of plastics requires the development of technologies enabling more efficient recycling solutions, converting waste plastics into harmless substances. Recycling methods, combining solvent-based recycling and mechanical recycling, are pivotal in this context.&#x0D; This study specifically focuses on the solvent-based and mechanical recycling of ABS materials. Wiring devices are prepared using a blend of 70% virgin ABS material and 30% recycled ABS (rABS) material, with this loop repeated three times. The aim is to evaluate the quality and acceptability of products derived from the blend of virgin and recycled ABS material after three times of cycle. Wiring devices, manufactured from mechanically ground broken ABS, undergo rigorous testing in each cycle. The experiments aim to assess the suitability and performance of recycled ABS material for mass production, facilitating an in-depth analysis of the material's life cycle. The mechanical test results demonstrate favorable outcomes for the recycled acrylonitrile butadiene styrene (rABS) materials, indicating comparable performance to the reference ABS virgin grade. While a marginal reduction in impact strength and tensile strength is observed when juxtaposed with the reference ABS virgin grade, the overall mechanical characteristics of rABS, remain consistent through successive recycling loops. These findings underscore the viability and resilience of rABS materials, positioning them as promising candidates for sustainable and environmentally conscious applications within the realm of polymer engineering. Through these efforts, the study contributes to sustainable plastic management practices, aligning with the broader goal of mitigating plastic pollution and promoting a more environmentally conscious approach. &#x0D;

Effect of aging on microstructure and mechanical properties of dissimilar steel welded joints between G115 and Sanicro25 steel

This paper studied the high-temperature stability of dissimilar steel welded joints between G115 and Sanicro25 steel. The joints were exposed to 700 °C for time up to 2000h. The microstructure evolution of base metal (BM) and fine-grain heat-affected zone (FGHAZ) were analyzed. Tensile, microhardness, and impact experiments were conducted on the joints, and the explanations for the changes in mechanical performance are derived from the microstructure. The results showed that the Laves phase were precipitated after aging for 100 h, which has two nucleation methods. Nucleation adjacent to M23C6 is the main way in this research. Laves phase mainly grows up to consume M23C6. The microstructure in BM and FGHAZ is obviously different after aging. After aging for 1000 h, mechanical properties such as tensile strength, Vickers hardness, impact energy, elongation and area reduction are reduced, except for the yield strength. The softening caused by the microstructure evolution of FGHAZ is the main reason for the joint fracture in FGHAZ.

Cracking resistance performance of epoxy asphalt mixture collected from in-service steel bridge deck pavement: Multiscale testing and evaluation

Epoxy asphalt (EA) mixture is commonly used in steel bridge deck paving due to its high strength and fatigue properties. However, cracking remains a problem on the steel bridge. The performance of damaged EA mixtures in the field after several years of service is unclear. Therefore, this study collected typical in-situ EA mixture and evaluated the attenuated performance of damaged materials at multiscale levels. The low- and intermediate-temperature cracking resistance and fatigue properties of field specimens from both the top and bottom layers were investigated by semi-circular bending (SCB) test. The micro-mechanics, microstructure, and element distribution of the interfacial transaction zone (ITZ) in damaged and fresh EA mixtures were characterized by the nano-indentation and energy dispersive spectrometer (EDS) tests. After 13 years of service at low and intermediate temperatures, the in-situ EA mixture exhibited a reduction in flexural tensile strength and fracture energy by approximately 31.4 % to 36.7 % and 54.9 % to 59.9 %, respectively. The top layer exhibited worse cracking resistance and fatigue properties than the bottom layer. The ITZ of the top layer showed more intense oxidation and significantly higher modulus than the bottom layer, contributing to the durability decay of the top layer EA mixture. The oxidative aging of the bottom layer was almost negligible compared to the new EA mixture, indicating that the degradation of the bottom layer was mainly caused by traffic or thermal loading from the steel bridge.

Enhancing concrete performance: Surface modification of recycled coarse aggregates for sustainable construction

In this study, the researchers introduce an innovative method to enhance the utilization of recycled coarse aggregates (RCA) derived from construction and demolition waste (C&D) in sustainable concrete production. The presence of old cements mortar on the surface of these aggregates poses a challenge to their mechanical properties. To tackle this issue, the researchers propose a unique approach that combines chemical treatment and abrasion techniques. Firstly, RCA is immersed in a 0.5 mol hydrochloric acid (HCl) solution, weakening the adhering mortar. Subsequently, abrasion treatment removes the weakened mortar from the RCA surface. The study explores the incorporation of these surface-modified RCAs at varying levels, from 0% to 100% in 25% increments. Various concrete properties, including workability, compressive strength, flexural strength, split tensile strength, and microstructural characteristics (XRD, SEM, and EDAX), along with modulus of elasticity, are assessed. Results indicate that the combination of these modification techniques significantly enhances RCA properties. At the 100% replacement level, surface-modified RCA results in a reduction of compressive, flexural, and split tensile strength by 08.31%, 10.61%, and 07.90%, respectively, in comparison to the reference concrete. Likewise, the modulus of elasticity decreases to 30.82, and porosity decreases to 27.82% at the same replacement level. However, SEM analysis illustrates improved bonding between RCA and cement matrix due to surface modifications, leading to reduced porosity and the formation of dense Interfacial Transition Zones (ITZs). Cost analysis reveals that recycled aggregate concrete (RAC) mixtures can be more economical than those utilizing natural aggregates (NA). In summary, this novel surface modification technique presents a promising avenue for optimizing RCA utilization in sustainable concrete production, promoting environmental conservation, and efficient waste management in the construction sector.

A Study of Annealing Effects on the Joints of a Rotary Friction Welds of AISI 1030 Steel

This study is concerned with the post-heat treatment of rotational friction welds. AISI 1030 carbon steel parts are welded by rotational friction welding (RFW). The welding process parameters include friction pressure (P1), friction time (T1); Forging pressure (P2), forging time (T2). During the friction phase, the rotational speed is 1450 rpm; after that, the welding parts is stopped immediately and pressed together. The weld samples will be annealed at 650 °C for 4 hours. The change in the properties of the material of a RFW weld joint such as hardness, tensile strength, bending strength as well as grain size when undergone a heat treatment process was investigated. The obtained results show that the annealing process strongly changes the mechanical properties through altering the microstructure of the weld. Particularly, the weld hardness and tensile strength decrease significantly while the bending strength and elongation increase as a result of the increase in grain size and uniformity of the phase distribution. The annealed weld has a hardness reduction of nearly 20% and a tensile strength reduction of about 24% compared to the original weld. The elongation in the tensile test increases from 1.1% for weld specimens to 2.54% for post-heat-treated welds. In the bending test, the maximum load before the appearance of cracks on the specimen increased by about 42% when comparing the post-heat and original weld specimens.

High cycle fatigue and corrosion behaviors of Mg3Zn/HA biodegradable composite

In this study, the effects of adding sub-micron hydroxyapatite (HA) particles were investigated on high cycle fatigue (HCF) and corrosion behaviors of Mg3Zn magnesium alloy. To this end, the Mg3Zn alloy and Mg3Zn/2.5 wt%HA bio composite were fabricated using mechanical-electromagnetic stir casting method followed by hot extrusion process. The results of the microstructural evaluation showed that grain refinement occurred in the composite by 48 % and Vickers microhardness increased approximately by 12 %. According to the results of the pH and weight loss measurements during the immersion tests, the presence of sub-micron HA particles increased the pH of the simulated body fluid (SBF) containing the composite specimens because of the micro-galvanic corrosion between the primary phase and the secondary phase of Ca2Mg6Zn3 in the matrix. However, a thicker protective surface layer formed on the composites, which may lead to a more desirable protection in the longer immersion time, compared to those of the monolithic alloy. Under the tensile monotonic load, the composite exhibited a moderate increase in the yield stress and a reduction in the ultimate tensile strength and the maximum strain at fracture, while the yield stress amelioration is more considerable under the compressive monotonic load. In comparison to the monolithic alloy, an improvement was observed in the high cycle fatigue behavior of the composite, which could be attributed to the yield stress enhancement, retarding the crack initiation under the same stress amplitudes.

Experimental and Numerical Study of Printing Strategy Impact on the Mechanical Properties of Sustainable PLA Materials.

This article is focused on a mechanical properties investigation of three types of sustainable poly lactic acid materials manufactured using the fused filament fabrication process. The purpose of this work was to study the impact of printing strategies on the mechanical properties and predict mechanical behavior under tensile loading using finite element analysis. The testing of mechanical properties was conducted according to the ISO 527 standard. The numerical simulations were conducted in Simufact Forming 2022 software. Analysis of the experimental data showed a dependance of mechanical properties on the used printing strategy. The Clear PLA samples printed in the XY plane exhibited a 43% reduction in tensile strength and a 49% reduction in elongation compared to samples printed from the same material in YZ plane. The experimental results show the influence of the printing orientation on the mechanical properties of 3D-printed samples.

Experimental study on tensile strength of granite residual soil during drying and wetting

The tensile strength of remolded granite residual soil under different water content conditions, during wetting and drying, was investigated using a self-made horizontal direct tension apparatus. The variations in tensile strength and the microcosmic mechanism of shrinkage crack formation and development were elucidated from the perspectives of suction stress and cementing force. Experimental results indicated that the tensile strength of granite residual soil initially increased and then decreased under different water content conditions. During the wetting process, the tensile strength followed a similar trend, but the peak strength (10 kPa) was lower compared to that under different water content conditions (22 kPa). The drying process exhibited three stages of tensile strength variation: a linear increase stage, a stationary stage, and a slight decrease stage. The peak value of the tensile strength during drying was much higher (reaching approximately 84 kPa) than that under different water content conditions and the wetting process. The tensile strength of remolded granite residual soil was solely controlled by suction stress under different water content conditions and in the wetting process. However, in the drying process, the tensile strength was also influenced by the cementing force, resulting in a peak value four times higher than that under different water content conditions and seven times higher than that in the wetting process. Suction stress served as the source of tensile stress in the soil during the drying process, and the development of cracks caused by suction stress led to a reduction in the overall tensile strength of the soil. Suction stress acted as both a contributor and a destroyer of soil tensile strength. During the drying process, the soil sample exhibited weakly acidic pH and gradually weakened hydrophilic ability. This led to the formation of stronger binding forces within the soil skeleton. Consequently, for soil samples with the same moisture content, the tensile strength during the drying process was much greater than in the other two situations. This study provides an alternative perspective on the source of soil tensile strength and its main controlling factors.

Radiation processing of bacterial cellulose-monolaurin wound dressing: Physicochemical effects, functional analysis, and sterilization.

A commercial bacterial cellulose-monolaurin wound dressing was investigated for changes in the chemical structure, mechanical strength, thermal degradation, morphology, and functional swelling properties after exposure to gamma and electron beam radiations at doses 15-50kGy. Radiation-induced oxidation occurred as seen in the FT-IR peaks at 1720-1750cm-1. Degradation of the cellulosic network was observed in tensile strength reduction and shift in degradation temperature to lower values. The SEM cross-section images of the irradiated dressings revealed a less dense nanostructure network compared to the non-irradiated samples while the XRD diffractograms indicated a change in lattice direction/plane. Despite these changes, irradiation caused no significant effect on the functional properties especially at 15-25kGy doses where most biomedical devices are sterilized. All irradiated wound dressings exhibited physical integrity, increased exudate absorption, and water vapor transmission rate - properties beneficial to wound-healing functionality. The pre-selected sterilization dose of 15kGy for each ionizing radiation was successfully verified and substantiated following ISO 11137-2:2016, hence ionizing radiation is a suitable sterilization modality for the product.

Bioactive Cellulose Nanopapers Impregnated with Cinnamon Essential Oil for Sustainable Antibacterial Packaging and Extended Shelf Life of Coriander Leaves

AbstractThis study introduces a novel approach by developing cellulose nanopapers derived from pineapple pomace and impregnated with cinnamon essential oil (CEO) in the range of 1–5 wt.%. This innovative material aims to enhance the shelf life of coriander leaves through antibacterial packaging. Comparative analyses encompassed structural, crystalline, morphological, physico‐mechanical, water barrier, permeability, and antibacterial properties against control samples. Incorporating CEO yielded a reduction in crystallinity index and tensile strength, attributed to a plasticizing effect. The addition of 5 wt.% CEO led to a remarkable 46% increase in elongation at break. Enhanced thermal stability, with a Tmax rise of 26 °C, is attributed to hydrogen bonding between CEO and cellulose molecules. The nanopapers exhibited notable reductions in oxygen and water vapor transmission rates (24% and 32% respectively) compared to control nanopapers. Impressive antibacterial activity against S. aureus and E. coli is observed. These developed nanopapers are applied as active packaging for coriander leaves, extending their shelf life by up to 3 and 15 days without and with refrigeration. Moreover, chlorophyll, carotenoid, and moisture content in coriander leaves stored with CEO‐loaded nanopapers remained akin to fresh leaves. Thus, this study presents an environmentally friendly antibacterial packaging solution with potential for sustainable application.

A comparative study of polycarbonate nanocomposites respectively containing graphene nanoplatelets, carbon nanotubes and carbon nanofibers

In industrial settings, thermoplastics are frequently employed as the base materials for composites and often enhanced with micron-sized additives such as glass fibers for improved performance. This study employed twin-screw extrusion as the processing method to compound a common thermoplastic – polycarbonate (PC) with one dimensional (1D) multi-walled carbon nanotubes (MWCNTs), carbon nanofibers (CNFs) and two dimensional (2D) graphene nanoplatelets (GNPs). In the PC matrix, GNPs were found to relatively uniformly dispersed, MWCNTs were seen to have two states of dispersion, and CNFs were much shortened with many defects caused by the extrusion. At 10.0 wt%, MWCNTs reduced the electrical resistivity of PC from 4.2 × 1015 to 4.6 × 107 Ω·cm, and GNPs improved the thermal conductivity from 0.13 to 0.38 W·m−1·K−1. GNPs, MWCNTs and CNFs at 1.0 wt% all improved the mechanical properties of PC, i.e. increments of 13.8%, 5.7% and 13.8% for Young's modulus, 6.2%, 11.7% and 21.2% for tensile strength, and 9.6%, 10.2% and 5.7% for impact strength. At 10.0 wt%, the PC/GNP nanocomposite displayed the least reduction of tensile strength of PC whilst the PC/CNF nanocomposite slightly increased the un-notched Charpy impact strength from 161 to 186 kJ/m2. The structure-property relationship of these nanocompsoites was analysed, with the relavent mechanisms proposed. Overall, twin-screw extrusion proved effective for dispersing various carbon nanomaterials in PC. This work provides a guide for industry to design and manufacture thermoplastic/carbon nanomaterial composites using the extrusion method.

Effects of ZnO/trimethylsilyl cellulose nano-composite coating on anti-UV and anti-fungal properties of papers

Trimethylsilyl cellulose (TMSC) was employed as the coating matrix for the application of zinc oxide nanoparticles (ZnO) onto paper surfaces and the protections of ZnO/TMSC coating against UV-induced damages and fungal spoilage were evaluated. Filter papers were immersed in 2% w/v TMSC solution loaded with ZnO and air-dried. Three ZnO/TMSC suspensions were prepared with 0.1, 0.5, and 1% w/v ZnO NPs. The presences of ZnO/TMSC protective layers were confirmed with ATR-IR spectroscopy. The coated papers exhibited high surface hydrophobicities. After the coated papers were subject to 365-nm UV irradiation at 400 W for 3 h, the contact angles dramatically dropped. The trimethylsilyl (TMS) groups exposed on the surface formed a moisture barrier and were partially removed on UV exposure. ATR-IR revealed that more TMS groups were removed in the protective layer with no ZnO. UV-irradiated papers turned yellow and papers protected with 1% ZnO/TMSC exhibited significantly lower color changes than that of the uncoated one. Compared to the TMSC-coated paper, the addition of ZnO resulted in a significant reduction in tensile strength at maximum. However, after UV irradiation, significant increases in both the strain at break and strength at maximum were only observed in 1% ZnO/TMSC-protected papers. Regarding their anti-fungal properties, the 1% ZnO/TMSC films were effective in growth inhibitions of Aspergillus sp. and Penicillium sp. on the nonirradiated papers. Despite being hydrophilic after UV-irradiation, growths of the molds were severely suppressed on the UV-irradiated paper.

Through the Forming Process of Femtosecond-Laser Nanotextured Sheets for Production of Complex 3D Parts

The use of ultra-short pulse lasers in the kW range, combined with an appropriate beam engineering approach, enables the achievement of high-throughput production of laser-functionalised surfaces. However, the manufacturing of complex parts still faces various challenges, such as difficulties in accessing regions with high aspect ratio shapes or intricate profiles, which often leads to the necessity of adapting the laser processing workstation to specific geometries. The forming process is a well-established technique for producing parts of any shape from metallic foils by imposing specific constraints. In this study, we aimed to assess the feasibility of producing laser-functionalised 3D complex products by the forming of laser-treated flat thin metallic sheets. Two-hundred micrometre-thick stainless-steel foils were textured with laser-induced periodic surface structures (LIPSS) through a roll-to-roll pilot line. First, we optimized the morphology of LIPSS. Subsequently, we conducted three types of mechanical tests on both laser-treated and untreated foils: standard tensile tests, fatigue tests, and cruciform specimen tests. We measured and compared parameters such as ultimate tensile strength, breaking strength, maximum elongation, and area reduction between specimens with and without LIPSS, all obtained from the same foil. Additionally, we utilized scanning electron microscopy (SEM) to compare the LIPSS morphology of laser-treated samples before and after mechanical tests.