Improvement In Impact Strength Research Articles

Elevating mechanical and thermal performance on alkali‐treated pineapple/glass fibre sandwich composite

AbstractThe present work generated hybrid composite sandwiches by incorporating 65% epoxy resin and 35% reinforcements derived from pineapple and glass fibres. The specimens were subjected to mechanical characterization by tensile, flexural and impact examinations. Among the untreated samples, the specimens containing untreated pineapple fibres (PF) with a composition of 17% PF, 18% glass fibres (three layers) and 65% epoxy by weight (17PF/TLGF) showed the most superior mechanical characteristics. Nevertheless, specimens containing fibres treated with NaOH exhibited exceptional characteristics, attaining a tensile strength of 88.121 MPa, a flexural strength of 94.213 MPa and an impact energy of 4.1 J. These data indicate a 20% enhancement in both tensile and flexural strength as well as a 63% improvement in impact strength compared to specimens containing 35% PF and lacking glass fibres (35PF/0GF). In comparison to 17PF/TLGF, the specimens treated with NaOH exhibited a 4.34% gain in tensile strength, a 4.24% increase in flexural strength and a 9% increase in impact strength. Experimental TGA was performed on the chemically treated fibre composite specimens, specifically identified as 35PF/0GF and 17PF/TLGF. Approximately 260 °C marked the beginning of decomposition for the 35PF/0GF sample, but the 17PF/TLGF sample decomposed at roughly 310°C. In addition, the fragmented surface of the 17PF/TLGF sample was analysed using SEM. © 2024 Society of Chemical Industry.

Compatibilizing and toughening of the styrene and acrylonitrile copolymer and core‐shell impact modifier obtained by agglomerate technologies

AbstractParticle size distribution and the compatibility of core‐shell impact modifiers play a crucial role in determining the mechanical properties of the resin. This study presents the synthesis of a core‐shell impact modifier, a copolymer of polybutadiene grafted with styrene and acrylonitrile (PBL‐g‐SAN), using emulsion polymerization to enhance the mechanical properties of SAN resin. Polymer agglomeration technologies were employed to increase the particle size of polybutadiene latex, resulting in particles approximately 300 nm in diameter. Moreover, the effects of core‐shell modifiers with different constitutions on the mechanical properties of ABS resin were investigated. By optimizing the grafting polymerization process, improvements in impact strength of ABS resin were observed. When the St/AN ratio of the core‐shell modifier is 75/25, with a core‐shell ratio of 60/40 and MMA content at 2.5%, the impact strength of ABS resin reaches its peak while maintaining high tensile strength. The incorporation of methyl methacrylate improved the dispersion of core‐shell modifiers in SAN resin. Compared to commercial ABS resins with the same SAN and rubber content, the modified resin demonstrated a nearly 20% improvement in impact performance, and significant reductions in both production time and costs due to the polymer agglomeration method.Highlights The 300 nm polybutadiene latex was synthesized by polymer agglomeration technology. The relationship between the composition of these core‐shell modifiers and the mechanical properties of ABS resin was explored. The ABS resin with impact strength exceeding 20% of commercial material is prepared.

Wire arc direct energy deposited multiphase steel through in situ micropowder alloying: mechanical and metallurgical studies

Purpose This study aims to investigate the effect of copper and titanium micropowder addition on the mechanical and metallurgical properties of additively manufactured low-carbon steel, aiming to produce a modified (multiphase) steel with ferritic low-carbon steel using in situ micropowder addition during wire arc direct energy deposition (WA-DED). Design/methodology/approach A robotic arm equipped with a GMA welding source deposited ER70S6 filler wire on AISI S235 substrate steel using WA-DED. Cu and Ti micropowders were interspersed between layers for microstructural modifications. Microscopy, spectroscopy, diffraction and mechanical testing were used to evaluate the properties of the deposited samples. Findings Incorporating Cu and Ti micropowders significantly enhanced the yield and tensile strength of the deposited material, showing an 83% increase in yield strength and a 33% increase in tensile strength. Microstructural analysis identified key phases such as ferrite, pearlite, bainite, retained austenite and martensite/austenite, with Cu and Ti acting as grain refiners. Nanoscaled Cu precipitates contribute to enhanced low-temperature toughness and a 150% improvement in impact strength at −30°C. Originality/value This study presents a novel approach to overcome the limitations of the available alloys (filler materials). This can be achieved by introducing in situ micropowder alloying during the WA-DED process. The micropowder addition allows altering the properties of the deposited material without changing the parent filler material itself, achieving the desired composition. With this approach, there is no need to manufacture the filler material with the preferred alloy composition separately and then carry out the deposition process.

A facile strategy for synthesizing isosorbide-based polyurethane structural adhesives and core–shell rubber

A structural adhesive series of biomass-based polyurethane (Biomass-PU) is synthesized using polypropylene glycol (PPG2000), isosorbide-based polyol (RPO300) as polyols, isophorone diisocyanate (IPDI) as an isocyanate and 4-tert-butylphenol (BP) as a capping agent. Three different equivalent ratios of PPG2000/RPO300, 9/1 (Biomass-PU1), 7/3 (Biomass-PU2), and 1/1 (Biomass-PU3), are evaluated to determine the effect of isosorbide-based polyol content on the properties and the optimizing formulation of biomass-PU structure adhesive. The 9/1 ratio of PPG2000/RPO300 substantially leads to the improvement of impact strength by up to 35 MPa, and the PPG2000/RPO300 = 9/1 ratio exhibits better thermal properties and impact strength than those of other ratios. To achieve more compatibility between biomass-PU structure adhesive and core–shell rubber (CSR) toughener, novel CSRs are successfully synthesized using acryl-PU as a shell and biomass-based PU as a core. The chemical structure of biomass-PU structure adhesives is analyzed through FT-IR Spectroscopy and NCO% titration. Thermal properties are evaluated using TGA and DSC analysis. Their molecular weights are measured by GPC. Also, the core–shell rubber (CSR) with a polyurethane shell is prepared to reinforce the impact strength of Biomass-PU structure adhesive.

Hybrid toughening effect of flax fiber and thermoplastic polyurethane elastomer in 3D‐printed polylactic acid composites

AbstractFlax fiber has emerged as a promising, eco‐friendly alternative to traditional synthetic reinforcement in polymer composites. However, manufacturing biocomposites using three‐dimensional (3D) printing technology is typically accompanied by significant processing challenges and weak product performance under dynamic loading conditions. This study aims to unlock the potential of 3D‐printed polylactic acid (PLA) by incorporating chemically modified chopped flax fibers and thermoplastic polyurethane elastomer to improve impact strength and processability. To achieve this, we employed the fused deposition modeling (FDM) technique to prepare composite specimens for the study. The crystallization behavior, tensile and impact properties, as well as the fracture behavior of the composites were investigated. The findings suggest that our approach stands out because it not only facilitates the challenging task of 3D printing PLA with fiber additives of high weight fraction and high aspect ratio but also results in a remarkable 120% enhancement in impact strength and an around 31.2% increase in tensile elongation compared to neat PLA, without compromising the elastic modulus.Highlights Flax fibers were modified through alkalization and silanization. Alkalization significantly enhanced printing quality. Silanization reduced fiber attrition and doubled the fiber aspect ratio. TPU particles facilitated the 3D printing of biocomposites. For the first time, the hybrid strategy doubled the impact strength of PLA.

Lignin-polylactic acid biopolymer blends for advanced applications – Effect of impact modifier

In this study, lignin underwent chemical modification via acetylation of hydroxyl groups to enhance its interfacial connection with poly (lactic acid) (PLA). Further enhancement of the blend was attained by adding an impact modifier, Biomax Strong. Incorporating Biomax Strong into PLA-lignin blends resulted in improvements in material characteristics, particularly in impact strength and thermal stability. This blend exhibited a unique set of mechanical properties, characterized by a reduction in tensile modulus as well as an increase in ductility. This will allow a more versatile use of PLA in various applications. The observed improved impact strength highlights the synergistic effect of stress redistribution within the PLA matrix contributing to widespread applications of PLA based composites. This can clearly be observed for the compound containing PLA and 15 wt.% lignin, where the impact strength was approximately 15 kJ/m2. With the addition of 5 wt.% impact modifier, the impact strength increased by 60 %, reaching approximately 25 kJ/m2. This synergy effect reinforces the overall structure, improving the impact toughness behavior. The combination of Biomax Strong and lignin not only address the limitations of PLA but also introduces new opportunities for applications requiring a balance of impact strength, ductility, and thermal stability. These advancements indicate a promising future for composite materials in various applications.

Polydopamine-primed FeCo-LDH endowed epoxy resin with enhanced flame retardancy and mechanical properties

The integration of layered double metal hydroxides (LDH) into epoxy resin (EP) for flame retardancy is in line with the principles of environmentally friendly and sustainable development. In this study, polydopamine (PDA)-primed intercalated LDH containing iron and cobalt ions (LDH-DBS@PDA) was prepared, and its chemical composition, structure and morphology were thoroughly characterized. Due to the synergistic flame-retardant properties exhibited by LDH and PDA, as well as the catalytic charring properties of iron and cobalt ions in both condensed and gaseous phases, EP composite with 5 wt% LDH-DBS@PDA achieved a UL-94 V-0 rating with a limiting oxygen index of 30.7 %. Moreover, EP/LDH-DBS@PDA exhibited a significant decrease in total heat release by 48 % and smoke release by 52 %, demonstrating remarkable fire safety performance. Additionally, the existence of LDH-DBS@PDA improved impact strength, tensile strength, and glass transition temperature due to strong interactions between PDA and EP matrix. This work presents a promising strategy for developing highly efficiency flame retardants with excellent compatibility for polymeric materials.

Experimental study on the effects of SS304 and Aluminium reinforcements on mechanical and vibration properties in jute‐epoxy composites

AbstractJute fiber has emerged as a promising reinforcement material in polymer composites, and researchers are actively exploring hybrid composite materials to overcome its individual mechanical property limitations and enhance overall performance. The paper introduces a unique hybridization of polymer composites that harnesses the advantages of stainless steel and aluminium offering a lightweight material for potential engineering applications. In this study, stainless steel 304 wire mesh (S), aluminium wire mesh (Al) and aluminium perforated sheet (Alp) are used as an additional reinforcement along with jute (J) and glass (G) fibers to fabricate hybrid polymer composites with varying volume fractions of SS304 and Al wire mesh. Seven laminates of hybrid composites namely J/J/J/S/J/J/J, J/J/S/J/J/S/J/J, J/J/J/Al/J/J/J, J/J/Al/J/J/Al/J/J, J/J/J/Alp/J/J/J, G/J/J/J/S/J/J/J/G, (J/J/S/J/J/S/J/J)450 along with virgin composite laminate J/J/J/J/J/J/J/J were fabricated and tested to obtain mechanical and vibration properties. Bonding between metal wire and matrix is investigated and reported through ILLS tests and SEM observations. Experimental findings indicate a notable 24% and 7% increase in tensile and ILSS strength, respectively, with SS304 reinforcement. Moreover, significant improvements in flexural and impact strength, approximately 48% and 33% for J/J/S/J/J/S/J/J, demonstrate the effectiveness of the hybrid approach. The J/J/S/J/J/S/J/J laminate excels in damping capacity under various boundary conditions. The study underscores the potential of metallic reinforcement to enhance the mechanical properties of jute fiber‐reinforced polymer composites, presenting opportunities for the development of lightweight, sustainable, and high‐performance materials in engineering applications.Highlights Developed jute fiber‐based hybrid polymer composites with metal wire reinforcement. Significant increase in strength and stiffness observed with addition of metal wires. Bonding between metal wire and matrix is investigated through ILLS tests and SEM observations. Vibration damping of all hybrid materials is reported. Study provides valuable data to develop sustainable, lightweight, and cost‐effective materials.

Enhancing performance of Prosopis juliflora fiber reinforced epoxy composites with silane treatment and Syzygium cumini filler

The utilization of natural fibers and fillers in composite materials has gained significant attention for their potential to enhance mechanical, thermal, and tribological properties while promoting sustainability. In this study, Prosopis juliflora fiber (PJF) reinforced epoxy composites, treated with silane and incorporating Syzygium cumini filler (SCF), were investigated to assess their performance across various parameters. The composites were subjected to comprehensive mechanical, tribological, thermo-gravimetric, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 3D profilometer, and morphology studies to elucidate the effects of silane treatment and SCF content on composite properties. The results of the mechanical characterization revealed significant improvements in tensile strength, impact strength, and microhardness in silane-treated composites with higher SCF content compared to untreated samples and those with lower SCF content. Specifically, the ST/SCF3 composite exhibited the highest values, with a tensile strength of 118.65 ± 4.63 MPa, impact strength of 27.83 ± 1.96 kJ/m2, and microhardness of 91.63 ± 2.84 HV. Tribological analysis indicated enhanced wear resistance and reduced coefficient of friction in silane-treated composites with higher SCF content, with the ST/SCF3 composite demonstrating the lowest wear loss (62 μm) and frictional force (5.2 N). Thermal characterization revealed improved thermal stability in silane-treated composites, particularly in the ST/SCF1 and ST/SCF3 formulations, suggesting increased resistance to temperature-induced degradation.

Production and mechanical characterization of Carbon fiber laminated composites modified by Graphene nano platelets (GnP) for high performance application

Polymeric materials play a pivotal role in diverse high-performance engineering domains, including aerospace, marine, automotive, and defense sectors. Their applications span from essential protective gear to intricate components vital for aircraft missiles, showcasing their versatility and significance in modern technology. The Graphene nano platelets (GnP) have the exceptional properties of a high contact area with the reinforcement material and enhanced synergistic effect, which is highly desired to improve the material performance. The present work describes the production of Carbon fiber laminated composites enhanced by Graphene nano Platelets (GnP) using a cost-effective Hand layup method (HLM). Herein, three different concentrations of GnP at 0.25, 1.0, and 1.75 wt% were used to modify the CFRP laminates. This is primarily performed to examine the viscoelastic and mechanical properties of the proposed GnP/CFRP sample. The findings of mechanical testing reveal that GnP nanofiller addition of 1.00 wt% significantly enhances the tensile and flexural properties by 20.7% and 10.05% respectively in comparison to neat sample. Also, the composites show satisfactory improvement in impact strength by 31.60% and enhanced viscoelastic properties at a 0.25 wt% of GnP loading. The XRD and DMA findings support GnP loading for high performance applications.

Analyzing Impact Strength Improvement in Polymer Laminates: A Comparative Study of Machine Direction Oriented (MDO)-PE/LLDPE and Polyamide (PA)/LLDPE Structures

The mechanical strength of 2 film structures, machine-direction-oriented polyethylene (MDO-PE) laminated with linear low-density polyethylene (LLDPE) and polyamide (PA) laminated with LLDPE was evaluated. PA/LLDPE films demonstrated superior impact strength (0.834 J/mm²) compared to MDO-PE/LLDPE films (0.445 J/mm²). Tensile strength for modified LLDPE (C₆) was 40 N/mm², higher than standard LLDPE (C₈) at 33 N/mm². The elongation at break for LLDPE reference C₈ was 689 %, compared to 682 % for LLDPE sample C₆. Film stiffness was measured at 162 MPa for the LLDPE reference C₈ and 122 MPa for the LLDPE sample C₆. PA films exhibited increased mechanical strength due to their intrinsic polyamide structure, while MDO-PE films benefited from molecular orientation during production. The modified LLDPE or C₆ displayed improved impact resistance and tensile strength with reduced stiffness. MDO-PE/LLDPE films are promising for sustainable and robust food packaging. HIGHLIGHTS Comparative Mechanical Strength of Films: Polyamide (PA) films, owing to their chemical structure rich in amide groups, exhibit superior mechanical strength compared to machine direction-oriented polyethylene (MDO-PE) films. Peeling Strength Dynamics: PA/LLDPE laminates display greater initial peeling strength; however, MDO-PE/LLDPE laminates show a gradual increase in peeling strength, indicating potential for improved long-term adhesion. Impact of LLDPE Density on Mechanical Properties: A comparison between LLDPE C₈ and LLDPE C₆ highlights the influence of polymer density on mechanical characteristics, with LLDPE C₆ demonstrating enhanced impact and tensile strengths at the expense of modulus and elongation. Strength Variability Among Laminates: The mechanical properties of laminated films are significantly influenced by the nature of their constituent layers, revealing the complexity of integrating polymers with differing characteristics. Potential of MDO-PE/LLDPE Laminates: Despite the superior properties of PA/LLDPE laminates, MDO-PE/LLDPE emerges as a viable alternative for sustainable and cost-effective packaging solutions, necessitating further validation to fully harness its advantages. GRAPHICAL ABSTRACT

Machine learning strategy to improve impact strength for PP/cellulose composites via selection of biomass fillers

ABSTRACT Lignocellulosic materials have inherent complexities and natural nanoarchitectures, such as various chemical constituents in wood cell walls, structural factors such as fillers, surface properties, and variations in production. Recently, the development of lignocellulosic filler-reinforced polymer composites has attracted increasing attention due to their potential in various industries, which are recognized for environmental sustainability and impressive mechanical properties. The growing demand for these composites comes with increased complexity regarding their specifications. Conventional trial-and-error methods to achieve desired properties are time-intensive and costly, posing challenges to efficient production. Addressing these issues, our research employs a data-driven approach to streamline the development of lignocellulosic composites. In this study, we developed a machine learning (ML)-assisted prediction model for the impact energy of the lignocellulosic filler-reinforced polypropylene (PP) composites. Firstly, we focused on the influence of natural supramolecular structures in biomass fillers, where the Fourier transform infrared spectra and the specific surface area are used, on the mechanical properties of the PP composites. Subsequently, the effectiveness of the ML model was verified by selecting and preparing promising composites. This model demonstrated sufficient accuracy for predicting the impact energy of the PP composites. In essence, this approach streamlines selecting wood species, saving valuable time.

Mechanical Properties of Basalt / Chopped E-Glass Fiber and Graphite Powder Reinforced Hybrid Composites

In the current investigation an effort has put to study the effect of E-glass chopped mat and graphite powder in variations of 5g, 10g, and 15g on the tensile and flexural behavior of a basalt fiber-reinforced epoxy composite laminate reinforced with E-Glass fiber and Graphite powder. Hand layup technique has been used for the fabrication of the composites. Tensile, flexural, impact, and hardness tests were done on the Basalt/E-glass/Graphite epoxy composite in accordance with ASTM standards. The results indicate significant improvement in tensile strength, impact strength and hardness when E-glass was incorporated in the basalt/epoxy composite. However, basalt/E-glass/10% graphite epoxy composite was shown to have a greater flexural strength. An excellent dispersion of the reinforcements in the polymeric matrix, which elevated surface area for solid interfacial contact and effective load transmission, could possibly be accountable for the improved performance of the laminates that were successfully developed.

Synergistic effects of organosilicon flame retardant and DOPO-based reactive compatibilizer for high performance PC/PBT composites

PC/PBT alloy is flammable resulting in fire safety hazards in practical applications and the existing flame retardants have a great influence on the mechanical properties, which limits its application range. Therefore, it is an urgent problem to improve the flame retardancy of PC/PBT alloy while taking its mechanical properties into account. Herein, a novel flame retardant and reactive compatibilizer was synthesized by grafting 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) onto ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA), named as DOPO-EG, to improve the flame retardancy and mechanical properties of PC/PBT alloy simultaneously. Additionally, based on the effective synergistic effect of enhancing the charring and flame retardancy between silicon and phosphorus, the organosilicon flame retardant (RMSi) is introduced and compounded with DOPO-EG to prepare excellent flame retardancy PC/PBT/DOPO-EG/RMSi composites. The results showed that the PC/PBT/DOPO-EG/RMSi composites with 10 wt% DOPO-EG and 8 wt% RMSi (CBE10P10Si8) reached UL-94 V-0 rating and the peak of heat release rate (PHRR) and total heat release rate (THR) of CBE10P10Si8 decreased by 42% and 16% respectively. This is due to the fact that DOPO is cracked into phosphorus radicals to capture and eliminate the active H and OH radicals, inhibiting the chain free radical reaction, and RMSi is enriched on the surface of CBE10P10Si8 to form an inorganic oxygen insulation protective layer during combustion. The impact strength of CBE10P10Si8 increased from 5.8 kJ/m2 to 11.9 kJ/m2. The improvement of impact strength is owing to the existence of DOPO-EG which promotes the formation of the interface layer between PC and PBT phases, resulting in the transfer of stress between the two phases. This work provides a new method for the preparation of PC/PBT alloy with excellent flame retardancy and mechanical properties, and also provides a certain reference value for the research of flame retardancy and toughening modification of polymer composites.

Cross-Linked Polyolefins through Tandem ROMP/Hydrogenation.

Cross-linked polyolefins have important advantages over their thermoplastic analogues, particularly improved impact strength and abrasion resistance, as well as increased chemical and thermal stability; however, most strategies for their production involve postpolymerization cross-linking of polyolefin chains. Here, a tandem ring-opening metathesis polymerization (ROMP)/hydrogenation approach is presented. Cyclooctene (COE)-co-dicyclopentadiene (DCPD) networks are first synthesized using ROMP, after which the dispersed Ru metathesis catalyst is activated for hydrogenation through the addition of hydrogen gas. The reaction temperature for hydrogenation must be sufficiently high to allow mobility within the system, as dictated by thermal transitions (i.e., glass and melting transitions) of the polymeric matrix. COE-rich materials exhibit branched-polyethylene-like crystallinity (25% crystallinity) and melting points (Tm = 107 °C), as well as excellent ductility (>750% extension), while majority DCPD materials are glassy (Tg = 84 °C) and much stiffer (E = 710 MPa); all materials exhibit high tensile toughness. Importantly, hydrogenation of olefins in these cross-linked materials leads to notable improvements in oxidative stability, as saturated networks do not experience the same substantial degradation of mechanical performance as their unsaturated counterparts upon prolonged exposure to air.

Molecular dynamics simulation and experimental study on the mechanical properties of PET nanocomposites filled with CaCO3, SiO2, and POE-g-GMA

Abstract This work investigated the mechanical properties of polyethylene terephthalate (PET) reinforced with calcium carbonate (CaCO3) and silica (SiO2) nanoparticles, respectively, and the improvement in toughness of the ternary system with the incorporation of graft-modified ethylene-1-octene copolymer (POE-g-GMA). PET nanocomposites were prepared by melt blending extrusion and injection molding. Molecular dynamics (MD) simulation was employed to construct models for binary system filled with nanoparticles and ternary system with the additional inclusion of POE-g-GMA elastomers. The results of mechanical property tests and MD simulation revealed that the binary system exhibited increased elastic modulus and tensile strength, mainly attributed to the effective reinforcement of rigid nanoparticles and the surface adsorption between nanoparticles and the PET matrix enhanced the interfacial interactions. CaCO3 indicated a more pronounced reinforcing effect, possibly due to the higher crystallinity of its composites. The incorporation of POE-g-GMA resulted in a significant improvement in impact strength and the elongation at break of PET nanocomposites. This enhancement in toughness is attributed to the elastomer’s ability to absorb a substantial amount of impact energy, while the elastic modulus is higher than that of pure PET.

Gadolinium oxide Nanoparticles Infusion in Heat-Cured Acrylic Denture Base Material: Impact on Glass Transition Temperature and Mechanical Strength Enhancement

Introduction: Nano dentistry has paved the way for advanced therapeutic opportunities in various dental disciplines, particularly in the improvement of oral health. One area of focus is the enhancement of mechanical properties of dental materials, such as acrylic resins commonly used in denture base materials. Various strategies, including chemical corrections and the addition of particles, have been explored to augment the mechanical qualities. This study investigates the impact of incorporating Gadolinium oxide nanoparticles into heat-cured acrylic denture materials. Materials and Methods: The denture base was processed using a standardized approach, with the addition of Gadolinium oxide nanoparticles during the monomer phase. A total of 120 specimens were fabricated. 30 specimens for each test using 10 specimens for each nanoparticle concentration (Control 0%, 1%, and 1,5% nanoparticles). The nanoparticles were dispersed using sonication to ensure uniform distribution. The study assessed properties such as glass transition temperature using a differential scanning calorimeter, impact strength and transverse strength utilizing an Instron universal testing machine, and surface roughness via profilometer measurements. Scanning electron microscope also utilized. One way ANOVA was used to determine the mean differences. Results: The study revealed significant improvements in glass transition temperature, impact strength, and transverse strength. The peak values were often seen in the 1.5% wt. group. Surface roughness, however, showed non-significant changes with nanoparticle additions, possibly due to the minimal involvement of nanoparticles on the outer surface. Conclusion: Incorporating Gadolinium oxide nanoparticles into heat-cured acrylic denture base materials demonstrated notable enhancements in key mechanical properties. The findings suggest that nanoparticle additions contribute to increased strength and rigidity, as evidenced by improvements in impact and transverse strength. However, surface roughness remained largely unaffected. This study contributes valuable insights into the potential benefits of nanotechnology in optimizing dental materials for improved clinical performance and patient outcomes.

Thermal, mechanical, electrical properties of poystyrene/poly (styrene-b-isobutylene-b-styrene/carbon nanotube nanocomposites

In this study, high impact polystyrene (HIPS) materials was prepared by using a styrenic elastomer (10, 20, 30 wt%) and carbon nanotube (CNT) (3, 5, 7, 10 phr) by melt blending technique as alternative to commercial HIPS including polybutadiene rubber. The poly (styrene- b-isobutylene- b-styrene) (SIBS) was used as thermoplastic elastomer with polystyrene (PS) to improve its poor impact resistance and CNT was added to PS/SIBS blend matrix to maintain its strength and stiffness. The modulus, tensile strength and toughness values of the blends decreased while those of impact resistance increased in comparison to neat PS. The impact strength of PS20SIBS blend containing 20 wt% SIBS was found to be approximately 530% higher than pure PS. The nanocomposites of the PS20SIBS exhibited a decrease in the size of SIBS particles with increasing CNT compared to PS20SIBS. This was ascribed to the increased viscosity of PS matrix via CNT filler, preventing the coalescence of the elastomer domains. Compared to the PS20SIS, its nanocomposites showed higher strength, modulus and toughness, but lower impact strength. The toughness of the nanocomposite containing 5 phr CNT (PS20SIBS-5CNT), increased by 117% while its creep deformation decreased by approximately 40%, in comparison with PS20SIBS blend. Although PS20SIBS-5CNT exhibited lower impact strength than the PS20SIBS blend due to the dispersion of smaller SIBS particles in the PS matrix, it still increased the impact strength of pure PS by 188%. The PS20SIBS-5CNT nanocomposite, which improved impact strength and creep resistance with optimal toughness and tensile modulus can be used as a novel HIPS material that tunes the hardness-toughness/impact balance effectively. Moreover, the same nanocomposite was found to reach the conductivity threshold by exhibiting 106 times lower electrical resistance in comparison with that containing 3 phr CNT, leading to a conductive filer network with 5 phr loading of the nanotubes into the system.

An Approach to Testing Antivandal Composite Materials as a Function of Their Thickness and Striker Shape-A Case Study.

Our research material comprised antivandal fire-retardant hybrid composites modified with inorganic and organic fillers intended for application in public transport vehicles. This paper presents an approach to studying their impact strength as a function of the composite thickness (3 to 6 mm) and striker shape (hemispherical, semicylindrical, wedge-shaped) used in the experimental stand. Group A composites, made of single fabric layers (n = 5), were thinner and their impact strength was lower by 73% than that for Group B composites made of double fabric layers. Study results show an almost threefold improvement in impact strength for a thickness increase of as little as 0.3 mm. Statistical analysis (the Shapiro-Wilk test, p > 0.05) did not show any significant differences in the quantitative evaluation of changes (n = 3) on the surface of the examined materials caused by impacts with strikers of different shapes. In turn, a linear correlation (Shapiro-Wilk test, W = 0.0857, p = 0.022) was found between impact strength and the thickness of the studied materials. It was observed that appropriate arrangement of fabrics and powder fillers can lead to a different distribution of forces and energy absorbed by the tested material. A lower impact strength was observed for the composite which had powder fillers in its composition, which caused the formation of microvoids in the structure of the material and thus led to a weakening in their strength properties. An effect of the placement of the glass fabric layer in the composite on the results was also observed. Moreover, SEM evaluation of the composites revealed their layered structure and the impregnation of woven fabrics with resin.

A Bio-Inspired Approach to Improve the Toughness of Brittle Bast Fibre-Reinforced Composites Using Cellulose Acetate Foils.

Bast fibre-reinforced plastics are characterised by good strength and stiffness but are often brittle due to the stiff and less ductile fibres. This study uses a biomimetic approach to improve impact strength. Based on the structure of the spicules of a deep-sea glass sponge, in which hard layers of bioglass alternate with soft layers of proteins, the toughness of kenaf/epoxy composites was significantly improved by a multilayer structure of kenaf and cellulose acetate (CA) foils as impact modifiers. Due to the alternating structure, cracks are deflected, and toughness is improved. One to five CA foils were stacked with kenaf layers and processed to composite plates with bio-based epoxy resin by compression moulding. Results have shown a significant improvement in toughness using CA foils due to increased crack propagation. The unnotched Charpy impact strength increased from 9.0 kJ/m2 of the pure kenaf/epoxy composite to 36.3 kJ/m2 for the sample containing five CA foils. The tensile and flexural strength ranged from 74 to 81 MPa and 112 to 125 MPa, respectively. The tensile modulus reached values between 9100 and 10,600 MPa, and the flexural modulus ranged between 7200 and 8100 MPa. The results demonstrate the successful implementation of an abstract transfer of biological role models to improve the toughness of brittle bast fibre-reinforced plastics.