Mechanical Properties Of Polymers Research Articles

High performance fully-printed strain-sensing e-textile for human posture recognition

Developing strain-sensing electronic textiles (e-textiles) that combine the functionality of stretchable strain sensors with the wearing comfort of textiles is an important development direction for wearable electronics. However, achieving low-cost and high-volume fabrication of strain-sensing e-textiles with both a wide strain working range and high sensitivity remains a huge challenge. Herein, we report high-performance printed strain-sensing e-textiles by designing the composite conductive ink from the perspective of optimizing polymer binders. The composite conductive inks based on different polymer binders present different rheological properties, volume shrinkage, and mechanical properties, which further affect the sensing performance of printed strain-sensing e-textiles. Compared with other four composite conductive inks, the carbon blacks/high elastic transparent glue-based printed strain-sensing e-textile with microcrack structure exhibits higher sensitivity (120.6 at a strain range of 0–100%) over a wide strain working range (150%), while also exhibiting low detection limits (0.1%) and outstanding dynamic stability (10000 cycles). On this basis, the demonstration of smart clothing integrated with 9 printed strain-sensing elements in human body posture recognition and monitoring proves its application prospects in human–machine interaction and virtual reality. This work opens a new research idea for constructing high-performance strain-sensing e-textiles.

Construction of hierarchical SiO2 microcapsule towards flame retardation, low toxicity and mechanical enhancement of epoxy resins

A novel approach for improving the flame retardancy, smoke suppression and mechanical properties of epoxy resins (EPs) has been proposed by incorporating functionalized hollow mesoporous silica microcapsules (SHP) loaded with phosphorous silane flame retardants (SCA) and coated with polydopamine (PDA) and transition metals. The proposed approach involves a multi-level structure that combines several mechanisms to enhance the flame-retardant properties of EP. The physical barrier provided by silica serves to impede heat and mass transfer during combustion, while the catalytic carbonization effect of phosphorus and transition metals promotes the formation of a protective char layer, which acts as a barrier to further flame propagation. Incorporating a low loading amount of 3 wt% SHP into the epoxy matrix resulted in EP/SHP-3 composites with significantly improved flame retardancy, as evidenced by a limiting oxygen index of 31.5% and a V-1 rating, in contrast to the values obtained for unmodified EP, which were 23.8% and no rating, respectively. In addition, cone calorimeter test (CCT) results indicated that the total heat release, peak heat release rate and total smoke production of EP/SHP-3 decreased by 18.2%, 25.2% and 18.4%, respectively. Moreover, the improved interfacial compatibility facilitated by polydopamine assists in the dispersion and compatibility of the SHP with the epoxy matrix, leading to better mechanical properties. Herein, the addition of 1 wt% SHP to EP significantly improved its mechanical performance, with a 16.7% increase in tensile strength and a 19.2% increase in impact strength. The design of the multi-level structural approach has the potential to provide new ideas for the simultaneous improvement of fire safety as well as mechanical properties of polymers.

A comprehensive review of the recent developments in thermoplastics and rubber blends‐based composites and nanocomposites

AbstractVarious blends and composites have been prepared during the past decade to address limitations, including the poor mechanical properties of polymers, or to balance out the high cost of synthetic polymers. Rubber‐based thermoplastic blends and composites are being developed to attain improved performance and balanced qualities for usage in a variety of industries, including automotive, packaging, home products, space technology, and biomedical. Thermoplastics can be produced via standard manufacturing procedures and have outstanding qualities like low density, good chemical resistance, and heat resistance. However, rubbers are being used because of their elastic attributes, including their resilience, impact resistance, and good tear strength. These two materials work well together when blended or combined. In this article, an effort was made to narrow the gap between rubbers and thermoplastics. The mechanical, rheological, and morphological properties of the rubber/thermoplastic blends and composites/nanocomposites containing various types of conventional fillers and nanofillers were discussed comprehensively. Blends of these materials can provide too easier melt processing as well as financial benefits. The flexible nature and damping properties of rubber and better thermal stability and thermoplastic processability contributed to the development of high‐performance rubber/thermoplastic composites with better ductility, impact strength, and stiffness. Rubber reduced the high brittleness of thermoplastics because of its resilience and damping properties. In contrast, the poor processability and weak chemical resistance of rubbers were overcome via better processability and higher stiffness of thermoplastics. Rubber‐based thermoplastic composites and nanocomposites have been reported to offer greater flexibility, better processing, high impact strength, and chemical resistance.Highlights The properties of rubber/thermoplastic blends were discussed in this article. More recent advancements in rubber/thermoplastic blends were evaluated. Morphological properties depend on the rubber/thermoplastic blend ratio. The addition of reinforcements affects the rheological properties. Dispersion of additives and blend ratio influence the mechanical properties.

Strain-rate dependence of mechanical characteristics of PLLA with different MW

Abstract Dynamic mechanical properties of polymers for biomedical applications are crucial parameters for development and engineering of new medical devices. Here, the time-dependent material behavior is a key factor for durability. Varying the strain rate is a convenient implementation of time-dependency for uniaxial testing. This study investigates time-dependence of Poly(L-Lactide) (PLLA) through uniaxial testing with different strain rates and PLLA with different molecular weight. The results show strain dependence for elongation at break and yield stress, Young’s modulus however is not rate dependent. An increase in elongation at break is also seen with increasing molecular weight of PLLA. Plastic strain increases significantly only for PLLA with an intermediate inherent viscosity. Results show distinct time dependencies regarding strain rate for PLLA with slightly different inherent viscosities. For stent-related mechanical material characteristics, higher molecular weight PLLA seems to be advantageous. This study only considers base materials, although appropriate thermal, mechanical as well as chemical post processing approaches for further adjustment of different properties have already been shown. A combination of the best possible base material and a suitable post-processing should be targeted.

Manufacture of Polymer Concrete Based on Snake-Fruit Seeds (Salacca zalacca) and Sawdust with Polyester Resin as an Adhesive

This study aims to determine the effect of adding snake-fruit (Salacca zalacca) seeds and sawdust on polymer concrete's physical and mechanical properties. The results showed that the highest physical properties were 1.27 g/cm3 density, 12.5% porosity, and 13.22% water absorption. The lowest physical properties are a density of 0.85 g/cm3, porosity of 2.65%, and water absorption of 2.07%. The highest mechanical properties are compressive strength of 16.70 MPa, tensile strength of 4.39 MPa, and flexural strength of 7.93 MPa. The lowest mechanical properties are compressive strength of 6.80 MPa, tensile strength of 1.11 MPa, and flexural strength of 1.50 MPa. SEM test results showed that the microstructure of polymer concrete showed differences between concrete samples A1 (consisting of 35 g of snake-fruit seeds, 15 g of sawdust, and 15 g of polyester resin) and polymer concrete samples B1 (consisting of 30 g of snake-fruit seeds, 15 g of sawdust, and 20 g of polyester resin). The SEM analysis of the A1 concrete sample reveals a dark surface color and conspicuous white lumps, which are attributed to polyester resin and arise from inadequate mixing of ingredients. In the case of sample B1, a higher concentration of visible resin lumps is observed.

Gelatine based gel polymer electrolyte towards more sustainable Lithium-Oxygen batteries

The lithium-oxygen battery has attracted wide interest thanks to its very high theoretical energy density, and as such it is considered by many as a valid battery of the future candidate. However, the challenges in its practical application are many, such as liquid electrolyte evaporation in semi-open systems, as well as solvents instability in a highly oxidizing environment. In this work, we propose to use gelatin, from cold water fish skin, a waste from the fishing industry, to prepare an efficient gel electrolyte for future Li-O2 battery applications. After a single step methacrylation in water, methacrylated gelatine is directly cross-linked in presence of liquid electrolyte through UV- initiated radical polymerization. The obtained gel polymer electrolytes present good thermal and mechanical properties, good electrochemical stability against Li metal and ionic conductivities as high as 2.51 mS cm−1 at room temperature. the Li-O2 cells assembled with this bio-renewable gel polymer electrolytes were able to perform more than 100 cycles at 0.1 mA cm−2, under constant O2 flow, at room temperature and at a fixed capacity of 0.2 mAh cm−2. Cathodes post- mortem analysis confirmed that the cross-linked gelatin matrix was able to slow down solvent degradation and therefore enhance the cell reversibility.

Polymer grafted aramid nanofiber reinforces immiscible waste polypropylene/poly(ethylene terephthalate)

AbstractPolypropylene (PP) and poly(ethylene terephthalate) (PET) are plastics commonly used for packaging because of their excellent barrier and mechanical properties. The properties of these plastics are often diminished after mechanical recycling, inevitably causing down‐cycling. This problem is exacerbated when different kinds of polymers mix. Aramid nanofibers have the potential to improve the mechanical properties of polymers due to their excellent mechanical properties but their poor dispersion in polymers is a challenge. Grafting polymers onto nanofibers can help address this challenge. In this work, different loading levels (1%, 2%, and 5%) of polymer grafted aramid nanofibers (ANFs) are blended with waste PP/PET (90/10), simulating a PP waste stream containing traces of PET contaminants. Scanning electronic microscopy, rheology, and differential scanning calorimetry results show the affinity of PP functionalized aramid nanofibers (PP_ANF) towards the PP matrix. At 1 wt% of the nanofiber, the size of the PET droplets in the PP matrix of the PP_ANF blend range from 0.2 to 2.0 μm while that of unmodified ANF and PET_ANF blends are in the range of 0.1–6.2 and 0.5–7.4 μm, respectively. In summary, polymer grafted ANFs have the tendency of improving properties of its like polymers due to similarity in the grafting polymer and the polymer matrix.

Dual bio-based epoxy resin as green substitute for DGEBA analogue with high performances

The epoxy resin made from petroleum-based bisphenol A has clear shortcomings both in raw material sustainability and the heat resistance as well as mechanical properties of polymers, which limits its use in high-performance products. A multifunctional epoxy resin was derived from sustainable resveratrol and phloroglucinol via a solvent-free procedure. The matrix showed its advantages in phase transition temperature (Tg, 247.5°C), storage modulus (4.14GPa), flexural strength (184.70 MPa), tensile modulus (6.14 GPa), and lap shear strength (28.15 MPa). Besides, the thermal conductivity (0.151 W/m•K), and coefficient of thermal expansion (84 ppm/°C) suggested its outstanding structural stability and dimensional stability below 250 °C. Moreover, it also possessed an intrinsic flame retardancy. The highly extended performances implied its promising applications in lightweight, fireproof, and heat insulation engineering.

Correlation between reference point indentation and mechanical properties of 3D-printed polymers

Reference point indentation (RPI) is a novel experimental technique designed to evaluate bone quality. This study utilizes two RPI instruments, BioDent and Osteoprobe, to investigate the mechanical responses of several 3D-printed polymers. We correlated the mechanical properties from a tensile test with the RPI parameters obtained from the BioDent and OsteoProbe. In addition, we tested the same polymers five years later (Age 5). The results show that for Age 0 polymers, the elastic modulus is highly correlated with average unloading slope (r = 0.87), first unloading slope (r = 0.85), bone material strength index (BMSi) (r = 0.85), average loading slope (r = 0.82), first indentation distance (r = 0.79), and total indentation distance (r = 0.76). The ultimate stress correlates significantly with first unloading slope (r = 0.85), average unloading slope (r = 0.83), BMSi (r = 0.81), first indentation distance (r = 0.73), average loading slope (r = 0.71), and total indentation distance (r = 0.70). The elongation has no significant correlation with the RPI parameters except with the average creep indentation distance (r = 0.60). For Age 5 polymers, correlations between mechanical properties and RPI parameters are low. This study illustrates the potential of RPI to assess the mechanical properties of polymers nondestructively with simple sample requirements. Furthermore, for the first time, 3D-printed polymers and aged polymers are investigated with RPI.

Molecular Dynamics Modeling for the Determination of Elastic Moduli of Polymer-Single-Walled Carbon Nanotube Composites.

The use of carbon nanotubes to improve the mechanical properties of polymers is one of the promising directions in materials science. The addition of single-walled carbon nanotubes (SWCNTs) to a polymer results in significant improvements in its mechanical, electrical, optical, and structural properties. However, the addition of SWCNTs does not always improve the polymer properties. Also, when a certain content of SWCNTs is exceeded, the mechanical properties of the nanocomposite become worse. This article reports the results of computer simulations for predicting the mechanical properties of polymer/single-walled carbon nanotube nanocomposites. The efficiency of reinforcing polymer composites is considered depending on the concentration of carbon nanotubes in the polymer matrix, their size, and structure. The elastic moduli of the nanocomposites are predicted using computer simulations for unit cell tension (0.1%). General trends in the mechanical properties of composites with polypropylene (PP), poly(ethyl methacrylate) (PEMA), polystyrene (PS) matrices, and SWCNTs are shown.

High-Throughput Screening and Prediction of High Modulus of Resilience Polymers Using Explainable Machine Learning.

The ability to store and release elastic strain energy, as well as mechanical strength, are crucial factors in both natural and man-made mechanical systems. The modulus of resilience (R) indicates a material's capacity to absorb and release elastic strain energy, with the yield strength (σy) and Young's modulus (E) as R = σy2/(2E) for linear elastic solids. To improve the R in linear elastic solids, a high σy and low E combination in materials is sought after. However, achieving this combination is a significant challenge as both properties typically increase together. To address this challenge, we propose a computational method to quickly identify polymers with a high modulus of resilience using machine learning (ML) and validate the predictions through high-fidelity molecular dynamics (MD) simulations. Our approach commences by training single-task ML models, multitask ML models, and Evidential Deep Learning models to forecast the mechanical properties of polymers based on experimentally reported values. Utilizing explainable ML models, we were able to determine the critical substructures that significantly impact the mechanical properties of polymers, such as E and σy. This information can be utilized to create and develop new polymers with improved mechanical characteristics. Our single-task and multitask ML models can predict the properties of 12 854 real polymers and 8 million hypothetical polyimides and uncover 10 new real polymers and 10 hypothetical polyimides with exceptional modulus of resilience. The improved modulus of resilience of these novel polymers was validated through MD simulations. Our method efficiently speeds up the discovery of high-performing polymers using ML predictions and MD validation and can be applied to other polymer material discovery challenges, such as polymer membranes, dielectric polymers, and more.

Effects of carbon nanotubes-based composites on the corrosion protection and mechanical properties of polymer coating in chloride environment

Carbon nanotubes (CNTs) possess excellent mechanical, thermal, electrical, electrochemical and optical properties. The combination of tungsten disulphide (WS2) and 3-aminopropyltriethoxysilane (APTES) with carbon nanotubes (CNTs) has improved the anticorrosive and mechanical capabilities of poly(p-phenylenediamine) (PpPD) coatings. Scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and X-Ray diffraction (XRD) techniques were used to characterize the composites such as APTES/CNTs, CNTs/WS2, and APTES/CNTs-WS2. As a result, the dielectric constant of PpPD was raised by 82 times at 102 Hz with the addition of just 0.6% APTES/CNTs-WS2. The APTES/CNTs-WS2 composite demonstrate improved anticorrosive and mechanical performance of the PpPD coating, according to electrochemical methods and mechanical testing. With a water contact angle (WCA) of 157°, this material is highly hydrophobic. Additionally, the PpPD-APTES/CNTs-WS2 was discovered to have significantly stronger resistance (17989 kΩ.cm2) than pure PpPD (101 kΩ.cm2), as well as significantly higher microhardness and tensile strength. The structure of the PpPD-APTES/CNTs-WS2 nanocomposite plays major role in enhancing the mechanical and anticorrosion properties. As a result, the PpPD-APTES/CNTs-WS2 nanocomposite may be used as a covering for solar panel frames.

Mechanical Properties of Polymer Modified Concrete with Steel Fiber

For the concrete used in highway, bridge and other structures, the problems such as the premature failure of the surface material and the failure of the interface between the surface course and the base course have not been solved, and the research at home and abroad mainly focuses on the strength and durability of concrete. It is also considered that polymer modified concrete and fiber reinforced concrete can improve the strength and toughness of concrete. This paper mainly studies the compressive and flexural properties of polymer modified fiber reinforced concrete. The experiment found that the mix design of styrene butadiene lotion modified steel fiber reinforced concrete proposed in this paper was reasonable, and the flexural strength at the age of 3 days reached 6.321Mpa, which was 16.9% higher than that of plain concrete; based on the plastic damage model (CDP) theory of concrete, the constitutive model of polymer modified fiber reinforced concrete is established, and the cubic concrete model is simulated under uniaxial compression, and the influence of concrete mortar with different strength substrates on the stress-strain field of uniaxial compression simulation is further analyzed.

Effect of post-processing on the mechanical properties of polymers printed by the fused filament fabrication method used as prosthodontic materials and dental biomaterials: a systematic review

Effect of post-processing on the mechanical properties of polymers printed by the fused filament fabrication method used as prosthodontic materials and dental biomaterials: a systematic review

Evaluation of Mechanical Properties of Bio-degradable Hybrid Particulate Fibre Reinforced Polymer Composite

Recent interest in advancement of biomaterials and their implant applications is well known. In the last five decades, great advances have been made in the field of biomaterials, including ceramics, glasses, polymers, composites, glass-ceramics and metal alloys. A variety of bio implants are currently used in body implantation. In the present study, ISO Polymer and crab shell derived hydroxyapatite (HAp) have been selected to develop composites by hand lay-up method targeted for degradable implant applications. Composite was successfully developed with various fractions of crab shell powder (0%, 5%, 10% and 15%) & e-glass fiber was composed to prepared hybrid polymer composites. HAp powder reinforced hybrid polymer composites, SEM studies and mechanical properties (hardness, tensile strength and impact strength) were determined as per ASTM standards. The higher mechanical properties were obtained at 15% Crabshell powder particulate composite. The introduced Crab Shell (HAp) enhances bio mineralization and promotes rapid healing rate in the bio medical implants applications.

A cellulose nanocrystals/tung oil-based multifunctional polymer with good mechanical properties, thermal stability, adhesive, self-healing, and recyclable properties

The vigorous development of dynamic covalent chemistry has inspired the study of dynamic covalent disulfide bond materials. However, the low bond energy of the disulfide bond leads to weak mechanical properties of polymers. Developing polymers with both self-healing and good mechanical properties is still a huge challenge. Herein, a novel fully bio-based multifunctional polymer (TCNC/TO) was designed by thioctic acid (TA), tung oil (TO), and cellulose nanocrystals (CNC). Tung oil (TO) was used as a cross-linking agent and free radical quenching agent. CNC was reacted with thioctic acid (TCNCs) as a reinforcing agent to enhance mechanical properties of TCNC/TO. The fully bio-based TCNC/TO exhibits promising self-healing ability (95% healing efficiency) and good mechanical properties (250% increase in tensile strength compared with polymers without CNC). Even after 10 cyclic tensile tests, the mechanical properties of TCNC/TO are not damaged. Furthermore, TCNC/TO possesses outstanding recyclability (still shows certain mechanical properties after repeated recycling) and adhesion (high adhesive strength towards various substrates). These impressive performances make TCNC/TO a candidate in the field of self-healing materials and adhesives.

The Effect of Heat Treatment on a 3D-Printed PLA Polymer’s Mechanical Properties

Three-dimensional printing is a useful and common process in additive manufacturing nowadays. The advantage of additive polymer technology is its rapidity and design freedom. Polymer materials' mechanical properties depend on the process parameters and the chemical composition of the polymer used. Mechanical properties are very important in product applicability. The mechanical properties of polymers can be enhanced by heat treatment. Additive-manufactured PLA's mechanical properties and structure can be modified via heat treatment after the 3D printing process. The goal of this research was to test the effect of heat treatment on the mechanical and structural parameters of additive-manufactured PLA. This was achieved via the FDM processing of standard PLA tensile test specimens with longitudinal and vertical printing orientations. After printing, the test specimens were heat-treated at 55 °C, 65 °C and 80 °C for 5 h and after being held at 20 °C for 15 h. The printed and heat-treated specimens were tested using tensile tests and microscopy. Based on the test results, we can conclude that the optimal heat treatment process temperature was 65 °C for 5 h. Under the heat treatment, the test specimens did not show any deformation, the tensile strength increased by 35% and the porosity of the PLA structure decreased.

Recent Biomedical Applications of Coupling Nanocomposite Polymeric Materials Reinforced with Variable Carbon Nanofillers.

The hybridization between polymers and carbon materials is one of the most recent and crucial study areas which abstracted more concern from scientists in the past few years. Polymers could be classified into two classes according to the source materials synthetic and natural. Synthetic polymeric materials have been applied over a floppy zone of industrial fields including the field of biomedicine. Carbon nanomaterials including (fullerene, carbon nanotubes, and graphene) classified as one of the most significant sources of hybrid materials. Nanocarbons are improving significantly mechanical properties of polymers in nanocomposites in addition to physical and chemical properties of the new materials. In all varieties of proposed bio-nanocomposites, a considerable improvement in the microbiological performance of the materials has been explored. Various polymeric materials and carbon-course nanofillers were present, along with antibacterial, antifungal, and anticancer products. This review spots the light on the types of synthetic polymers-based carbon materials and presented state-of-art examples on their application in the area of biomedicine.

Photo- and Water-Degradation Phenomena of ZnO Bio-Blend Based on Poly(lactic acid) and Polyamide 11.

The goal of this work was to investigate the morphological and chemical-physical changes induced by adding ZnO nanoparticles to bio-based polymeric materials based on polylactic acid (PLA) and polyamide 11 (PA11). Precisely, the photo- and water-degradation phenomena of nanocomposite materials were monitored. For this purpose, the formulation and characterization of novel bio-nanocomposite blends based on PLA and PA11 at a ratio of 70/30 wt.% filled with zinc oxide (ZnO) nanostructures at different percentages were performed. The effect of ZnO nanoparticles (≤2 wt.%) within the blends was thoroughly explored by employing thermogravimetry (TGA), size exclusion chromatography (SEC), matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and scanning and transmission electron microscopy (SEM and TEM). Adding up to 1% wt. of ZnO resulted in a higher thermal stability of the PA11/PLA blends, with a decrement lower than 8% in terms of molar masses (MMs) values being obtained during blend processing at 200 °C. ZnO promoted trans-ester-amide reactions between the two polymers, leading to the formation of PLA/PA11 copolymers. These species could work as compatibilisers at the polymer interface, improving thermal and mechanical properties. However, the addition of higher quantities of ZnO affected such properties, influencing the photo-oxidative behaviour and thus thwarting the material's application for packaging use. The PLA and blend formulations were subjected to natural aging in seawater for two weeks under natural light exposure. The 0.5% wt. ZnO sample induced polymer degradation with a decrease of 34% in the MMs compared to the neat samples.

Carbon Nanotube-Based Intumescent Flame Retardants Achieve High-Efficiency Flame Retardancy and Simultaneously Avoid Mechanical Property Loss.

Intumescent flame retardants (IFR) are an excellent solution to the problem of easy combustion of polymers. Still, the negative effect of the addition of flame retardants is the decline of the mechanical properties of polymers. In this context, carbon nanotubes (CNTs) are modified with tannic acid (TA) and then wrapped on the surface of ammonium polyphosphate (APP) to construct a special intumescent flame retardant structure (CTAPP). The respective advantages of the three components in the structure are explained in detail, especially the role of CNTs with high thermal conductivity in the flame retardant system. Compared with pure natural rubber (NR), the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) of the composites proposed with special structural flame retardants are decreased by 68.4%, 64.3%, and 49.3%, respectively, while the limiting oxygen index (LOI) increased to 28.6%. The TA-modified CNTs wrapped on the surface of APP can effectively reduce the mechanical damage caused by the flame retardant to the polymer. To sum up, the flame retardant structure of TA-modified CNTs wrapped on APP can effectively enhance the flame retardant properties of the NR matrix and reduce the negative impact on mechanics caused by adding APP flame retardant.