Fabrication Of Polymer Nanocomposites Research Articles

Structural, dielectric, and optical properties based on spinel ferrite (Mn0.5Fe1.5Mg0.5Ni0.5O4) nanoparticles filler reinforced PVA for optoelectronic, laser CUT-OFF filters and energy storage devices

The fabrication of polymer nanocomposites with specialized traits is gaining popularity across the world due to novel added qualities. In this work we used a flash auto-combustion method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles and the casting method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite polymer films with doping of nanoparticles various from 1–5 wt.%. The effect of Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles addition on the structural, optical, and dielectric characteristics of nanocomposite polymer films was analyzed. The structural properties were studied using x-ray diffraction pattern, high resolution transmission electron microscope, Fourier transform infrared, and field emission scanning electron microscope. The effects of nanoparticles doping on ac conductivity, electric modulus, impedance, and dielectric constant were investigated. It shows that Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite films have higher values of permittivity and ac conductivity than PVA and exhibit lower values of dielectric loss, electric modulus, and impedance. The optical properties showed the indirect optical decreased from 4.8 to 4.4 eV. According to the experimental results, these nanocomposite polymer films show promise for laser CUT-OFF filters and energy storage devices.

Computational modeling of passive transport of functionalized nanoparticles.

Functionalized nanoparticles (NPs) are complex objects present in a variety of systems ranging from synthetic grafted nanoparticles to viruses. The morphology and number of the decorating groups can vary widely between systems. Thus, the modeling of functionalized NPs typically considers simplified spherical objects as a first-order approximation. At the nanoscale label, complex hydrodynamic interactions are expected to emerge as the morphological features of the particles change, and they can be further amplified when the NPs are confined or near walls. Direct estimation of these variations can be inferred via diffusion coefficients of the NPs. However, the evaluation of the coefficients requires an improved representation of the NPs morphology to reproduce important features hidden by simplified spherical models. Here, we characterize the passive transport of free and confined functionalized nanoparticles using the Rigid Multi-Blob (RMB) method. The main advantage of RMB is its versatility to approximate the mobility of complex structures at the nanoscale with significant accuracy and reduced computational cost. In particular, we investigate the effect of functional groups' distribution, size, and morphology over nanoparticle translational and rotational diffusion. We identify that the presence of functional groups significantly affects the rotational diffusion of the nanoparticles; moreover, the morphology of the groups and number induce characteristic mobility reduction compared to non-functionalized nanoparticles. Confined NPs also evidenced important alterations in their diffusivity, with distinctive signatures in the off-diagonal contributions of the rotational diffusion. These results can be exploited in various applications, including biomedical, polymer nanocomposite fabrication, drug delivery, and imaging.

Surface Modification of Hetero-phase Nanoparticles for Low-Cost Solution-Processable High-k Dielectric Polymer Nanocomposites.

The surface modification of nanoparticles (NPs) is crucial for fabricating polymer nanocomposites (NCs) with high dielectric permittivity. Here, we systematically studied the effect of surface functionalization of TiO2 and BaTiO3 NPs to enhance the dielectric permittivity of polyvinylidene fluoride (PVDF) NCs by 23 and 74%, respectively, measured at a frequency of 1 kHz. To further increase the dielectric permittivity of PVDF/NPs-based NCs, we developed a new hetero-phase filler-based approach that is cost-effective and easy to implement. At a 1:3 mixing ratio of TiO2:BaTiO3 NPs, the dielectric constant of the ensuing NC is found to be 50.2, which is comparable with the functionalized BaTiO3-based NC. The highest dielectric constant value of 76.1 measured at 1 kHz was achieved using the (3-aminopropyl)triethoxysilane (APTES)-modified hetero-phase-based PVDF composite at a volume concentration of 5%. This work is an important step toward inexpensive and easy-to-process high-k nanocomposite dielectrics.

Mild air oxidation of boron nitride nanotubes. Application as nanofillers for thermally conductive polycarbonate nanocomposites

Boron nitride nanotubes (BNNTs) have experienced considerable growth in recent years due to their unique intrinsic properties, in particular for the fabrication of polymer nanocomposites. Dispersion of pure BNNTs in nanocomposites is often difficult due to their poor compatibility with most polymer matrices. An approach involving the creation of hydroxyl groups on their surface could improve their dispersion. While some harsh oxidation processes have been reported so far, a mild oxidation of BNNTs using air as the oxidant is reported here. This new catalytic reaction leads to slightly oxidized BNNTs, which were characterized by scanning electron microscope, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. Polycarbonate nanocomposites were then fabricated using pristine and oxidized BNNTs as nanofillers. The measured thermal conductivity increased linearly with the mildly oxidized BNNTs content. It reached a five-fold increase up to 1.19 W m.K−1 at 15% vol. content which is significantly improved over nanocomposites fabricated with severely oxidized BNNTs, while the electrically insulating character remained unchanged.

A review on lignin based nanocomposites: Fabrication, characterization and application

Polymer Composite material is made of two or more constituent materials that, when combined, produce a material with properties that are distinct from those of the individual constituents. The fabrication of polymer nanocomposites especially lignin-based nanocomposites are growing prospective research interest, thanks to various advancements made possible by the combination of a polymeric matrix with, in most cases, an inorganic nonmaterial. The advancement and modification of lignin-based nanocomposites is a step towards the replacement of conventional plastics (traditional polymer). Polymer composites have been produced or formed specifically for a variety of applications that are employed in a specific location for a specific purpose. Lignin is a highly heterogeneous polymer that is found naturally in plants that account for up to 15–35% of woody biomass made up of several precursors. Lignols that crosslink in a variety of ways with antioxidant property, high thermal stability, biodegradability, and UV absorption characteristics. Despite the fact that lignin is the most prevalent phenolic component in nature, and a small percentage of lignin removed by industrial processing which gets turned into dispersants and fillers has the potential to enhance various properties like mechanical, thermal, thermo-chemical, anticorrosive, flame retardant and many more of the polymer composite which is beneficial for our society as well our environment.

The Dispersion and Coagulation of Negatively Charged Ca2Nb3O10 Perovskite Nanosheets in Sodium Alginate Dispersion.

Chemically exfoliated nanosheets have been extensively employed as functional nanofillers for the fabrication of polymer nanocomposites due to their remarkable electrical, magnetic and optical properties. However, achieving a good dispersion of charged nanosheets in polymer matrix, which will determine the performance of polymer nanocomposites, remains a challenge. Herein, we investigated the dispersion and aggregation behavior of negatively charged Ca2Nb3O10 (CNO) perovskite nanosheets in negatively charged sodium alginate (SA) aqueous dispersion using dynamic light scattering (DLS). When CNO nanosheets meet with SA, aggregation and coagulation inevitably occurred owing to the absorption of SA on nanosheets. By controlling the electrostatic attraction between positively charged poly(ethylene imine) (PEI) and negatively charged SA, the charge density and hydrodynamic size of SA can be tuned to enable the good dispersion of CNO nanosheets in SA. This result may provide a new strategy to achieve the good dispersion of charged nanosheets in charged polymers for the rational design of multifunctional nanocomposites.

A study of the mechanical performance of nanocomposites of polyethylene containing exfoliated boron nitride nanoplatelets

AbstractBoron nitride nanoplatelets (BNNPs) are emerging as a potential candidate for developing polymer‐based thermally conducting nanocomposites that have electrically insulating properties. Generally, the mechanical performance of such polymer‐based nanocomposites, for example, toughness, is often found to be inferior, primarily, owing to the poor dispersion of BNNP, resulting from weaker interfacial interactions between BNNPs and polymer matrices. Here, we report on a successful method to fabricate high density polyethylene (HDPE)/BNNP nanocomposites, with superior mechanical properties, through the in situ exfoliation of the nanofiller via a melt‐extrusion technique. The results obtained showed that the toughness of a nanocomposite with 15 wt% BNNP loading is 18.8 × 103 KJ m−3, that is, about 1.5 times enhancement as compared to the control HDPE sample. The enhancement in mechanical properties can be attributed to a greater degree of homogeneous dispersion of the exfoliated BNNPs achieved using the melt‐ extrusion route. The results that were analyzed through scanning electron microscope and Fourier transform infrared measurements showed that an interesting microstructural feature, named “sunflower‐like” core‐shell structure, formed owing to the relatively stronger interactions between BNNPs and polyethylene chains, which in turn facilitated the uniform dispersion of exfoliated BNNPs in HDPE matrix. This work, therefore, opens up a pathway toward an easy and up‐scalable version for fabricating polymer nanocomposites that have superior mechanical performance and with wider applicability.

Superior energy storage of sandwiched PVDF films by separate introduction of core-shell Ag@BT nanoparticles and 2D MXene nanosheets

Polymer-based dielectrics exhibit promising applications in energy storage devices due to their enormous power density, good flexibility, and low cost. However, the low energy storage density remains to be the bottleneck. Here, sandwiched polymer-ceramic nanocomposite films are designed by stacking the PVDF middle layer incorporated Ag-decorated BaTiO3 (BT) ceramic nanoparticles (Ag@BT NPs) and the PVDF top/bottom layers embedded 2D layered MXene nanosheets. Interestingly, the optimal performances with a reversible energy storage density (Wre) as high as ∼ 22.3 J/cm3 with an efficiency η ∼ 77% at a low electric field of 270 MV/m are achieved for the film with 5 wt% DA@Ag@BT/PVDF middle layer. Strong interfacial coupling, ionic interaction, and enhanced breakdown strength due to the Coulomb blocking effect in the hierarchical structures with different fillers are responsible for the high energy storage performance. Moreover, the phase-field simulation further proved an appropriate amount of DA@Ag@BT NPs can effectively prevent the formation of the conductive network, inhibit the dielectric loss and improve the breakdown strength. This hierarchical strategy demonstrates an applicable route for fabricating polymer nanocomposites with high performance.

Antimicrobial polymeric composites in consumer goods and healthcare sector: A healthier way to prevent infection

AbstractPolymeric goods have been instrumental due to its versatility, properties like hygienic, lightweight, flexible, and highly durable and hence it accounts for the largest usage of applications worldwide in sectors like electrical, electronic, packaging, automotive, energy generation, furniture, marine, aerospace, military, consumer goods, construction, medical and healthcare, and so forth. However, as the demand for consumer goods continues to grow—from smartphones, smart watches to automobiles, home appliances, food packaging, pharmacy, and so forth; disease transmission (especially during the outbreak of epidemic/pandemic) via tangibility has emerged as a major hurdle to cater the out breaking microbial transmission through touch. The surfaces of these goods/products are required to suffice antimicrobial properties to prevent such contagious surface transmission. Considering the current challenges and need for antimicrobial polymer, a review is presented to collectively enlist the theoretical fundamental; commercial, R&D activities, economic performance, and challenges on large‐scale practice of antimicrobial polymeric products. The review also enumerates the potential antimicrobial nanofillers used for the fabrication of polymer nanocomposites with biostatic and biocidal properties along with expected property enhancement.

Research progress on the correlation between properties of nanoparticles and their dispersion states in polymer matrix

AbstractWhen fabricating polymer nanocomposites (PNCs), it is difficult for nanoparticles to disperse stably in polymer matrix since their high‐surface energy can cause them to attract each other. In this paper, we review the effects of nanoparticle size, surface chemical properties, and thermodynamic parameters on the dispersion state of nanoparticles (including inorganic and organic particles) in PNCs and describe some key measures to promote the nanoparticles dispersion. The ideal nanoparticles dispersion in polymer melt is available when the particle size is smaller than the rotation radius of polymer chains and the particle surface is highly compatible or has interactions with the matrix. In polymer solution, establishing proper thermodynamic parameters is necessary to ensure the balance interactions among particles, solvents, and polymers, leading to the successful preparation of PNCs with ideal structure. These results could supply theoretical suggestions for the design of PNCs. Moreover, the equilibrium dispersion may be unavailable without reasonable kinetic parameters, even if the dispersion process is thermodynamically favorable. Therefore, more studies are required on both thermodynamics and kinetics of the dispersion process.

Hybridization of MMT/Lignocellulosic Fiber Reinforced Polymer Nanocomposites for Structural Applications: A Review

In the recent past, significant research effort has been dedicated to examining the usage of nanomaterials hybridized with lignocellulosic fibers as reinforcement in the fabrication of polymer nanocomposites. The introduction of nanoparticles like montmorillonite (MMT) nanoclay was found to increase the strength, modulus of elasticity and stiffness of composites and provide thermal stability. The resulting composite materials has figured prominently in research and development efforts devoted to nanocomposites and are often used as strengthening agents, especially for structural applications. The distinct properties of MMT, namely its hydrophilicity, as well as high strength, high aspect ratio and high modulus, aids in the dispersion of this inorganic crystalline layer in water-soluble polymers. The ability of MMT nanoclay to intercalate into the interlayer space of monomers and polymers is used, followed by the exfoliation of filler particles into monolayers of nanoscale particles. The present review article intends to provide a general overview of the features of the structure, chemical composition, and properties of MMT nanoclay and lignocellulosic fibers. Some of the techniques used for obtaining polymer nanocomposites based on lignocellulosic fibers and MMT nanoclay are described: (i) conventional, (ii) intercalation, (iii) melt intercalation, and (iv) in situ polymerization methods. This review also comprehensively discusses the mechanical, thermal, and flame retardancy properties of MMT-based polymer nanocomposites. The valuable properties of MMT nanoclay and lignocellulose fibers allow us to expand the possibilities of using polymer nanocomposites in various advanced industrial applications.

Polymer nanocomposites comprising PVA matrix and AgGaO2 nanofillers: Probing the effect of intercalation on optical and dielectric response for optoelectronic applications

Objectives: Synthesis of hybrid nanoparticles (NPs) and intercalation of as prepared NPs inside polymer matrix to fabricate polymer nanocomposites (NC) and evaluate the optoelectronic properties. Method: A simple, time consuming solution combustion method was used to synthesize silver doped gallium oxide (AgGaO2) NPs. The solution casting process was employed to prepare NC films of poly(vinyl alcohol) (PVA) with the inclusion of AgGaO2 NPs as nanofiller. Finding: The analytical technique such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and differential scanning calorimetry analyses were used to analyze the PVA/AgGaO2 NC films. The findings of various characterization approaches showed that the morphological, structural and thermal characteristics of PVA/AgGaO2 NC films had improved, as well as confirms the existence of AgGaO2 NPs in the PVA matrix. Furthermore, the dielectric characteristics of the PVA/AgGaO2 NC films were studied using an LCR meter at various frequencies (50 Hz–1 MHz). With intercalating four different wt% of AgGaO2 NPs content as 0.5, 1, 2 and 4 wt% the dielectric constant and dielectric loss of NC films with 4 wt % AgGaO2 NPs incorporated were 112.1 and 51.5 respectively. Novelty: This improvement in dielectric characteristics revealed the uniform distribution and effective interaction of AgGaO2 NPs with the active site of PVA chains. The preceding findings demonstrated that the obtained PVA NCs were promising materials for flexible energy storage and UV-shielding applications. Keywords: Hybrid metal oxides; Dielectric constant and dielectric loss; AC conductivity; Optical energy band gap

One-pot exfoliation and synthesis of hydroxyapatite-functionalized graphene as multifunctional nanomaterials based on electrochemical approach

Based on electrochemical exfoliation route, a simplified one-pot approach was put forward to obtain hydroxyapatite-functionalized graphene (GNS@HAP), as a multifunctional nanomaterial. The disappearance of characteristic peaks in XRD results and the microstructure morphology observed by electron microscope observation directly confirmed the successful exfoliation and functionalization of graphene in one pot process. Compared with pure graphene which has few functional groups, GNS@HAP can strongly interact with polymer chains by introducing uniformly-dispersed rod-like hydroxyapatite. Moreover, GNS@HAP presents more significant enhancement effects in flame retardancy, toxic gas suppression and mechanical property of thermoplastic polyurethane (TPU) nanocomposites. The peak values of heat release rate and total heat release of TPU-GNS@HAP-2.0 were decreased by 24.4% and 19.8%, respectively. The simplified one-pot electrochemical route offers an environmentally friendly and commercially available method to develop the application of graphene in fabricating polymer nanocomposites.

Application of r-GO-MMT Hybrid Nanofillers for Improving Strength and Flame Retardancy of Epoxy/Glass Fibre Composites

The application of nanomaterials as a strengthening agent in the fabrication of polymer nanocomposites has gained significant attention due to distinctive properties which can be utilised in structural applications. In this study, reduced graphene oxide (r-GO) and montmorillonite (MMT) nanoclay were used as filler materials to fabricate hybrid epoxy-based nanocomposites. The synergistic effect of nanomaterials on flammability and mechanical behaviour of nanocomposites were studied. Results revealed that the addition of nanofiller showcases 97% and 44.5% improvement in tensile and flexural strength. However, an increment in the percentage of filler material over 0.3% exhibits a decremental mechanical property trend. Likewise, the addition of nanofiller increases the nonignition timing of the glass-fibre-reinforced epoxy composites. Fracture surface morphology displays the occurrence of the ductile fracture mechanism owing to the presence of hybrid fillers.

Processes and Properties of Ionic Liquid-Modified Nanofiller/Polymer Nanocomposites—A Succinct Review

Ionic liquids can typically be synthesized via protonation, alkylation, metathesis, or neutralization reactions. The many types of ionic liquids have increased their attractiveness to researchers for employment in various areas, including in polymer composites. Recently, ionic liquids have been employed to modify nanofillers for the fabrication of polymer nanocomposites with improved physicochemical properties. In this succinct review, four types of imidazolium-based ionic liquids that are employed as modifiers—specifically alkylimidazolium halide, alkylimidazolium hexafluorophosphate, alkylimidazolium tetrafluoroborate, and alkylimidazolium bistriflimide—are reviewed. Additionally, three types of ionic liquid-modified nanofiller/polymer nanocomposites—namely ionic liquid-nanofiller/thermoplastic nanocomposites, ionic liquid-nanofiller/elastomer nanocomposites, and ionic liquid-nanofiller/thermoset nanocomposites—are described as well. The effect of imidazolium-based ionic liquids on the thermo-mechanico-chemical properties of the polymer nanocomposites is also succinctly reviewed. This review can serve as an initial guide for polymer composite researchers in modifying nanofillers by means of ionic liquids for improving the performance of polymer nanocomposites.

Hierarchically Structured Composite Fibers for Real Nanoscale Manipulation of Carbon Nanotubes

AbstractCarbon nanotube (CNT)‐reinforced polymer fibers have broad applications in electrical, thermal, optical, and smart applications. The key for mechanically robust fibers is the precise microstructural control of these CNTs, including their location, dispersion, and orientation. A new methodology is presented here that combines dry‐jet‐wet spinning and forced assembly for scalable fabrication of fiber composites, consisting of alternating layers of polyacrylonitrile (PAN) and CNT/PAN. The thickness of each layer is controlled during the multiplication process, with resolutions down to the nanometer scale. The introduction of alternating layers facilitates the quality of CNT dispersion due to nanoscale confinement, and at the same time, enhances their orientation due to shear stress generated at each layer interface. In a demonstration example, with 0.5 wt% CNTs loading and the inclusion of 170 nm thick layers, a composite fiber shows a significant mechanical enhancement, namely, a 46.4% increase in modulus and a 39.5% increase in strength compared to a pure PAN fiber. Beyond mechanical reinforcement, the presented fabrication method is expected to have enormous potential for scalable fabrication of polymer nanocomposites with complex structural features for versatile applications.

Highly conductive polyimide nanocomposite prepared using a graphene oxide liquid crystal scaffold

High loading of aligned graphene filler is effective for fabricating polymer nanocomposites with drastically improved properties, while practical preparation of such composites remains elusive. This paper reports on a method of preparing polyimide (PI, BPDA/PDA) nanocomposites containing highly loaded graphene fillers that are uniformly aligned parallel to the coating substrate in the PI matrix. The highly aligned graphene/PI film was achieved by infiltrating water-soluble poly(amic acid) ammonium salt (PAAS) into the scaffold of the graphene oxide liquid crystal. After thermal treatment, a freestanding reduced graphene oxide/polyimide (rGO/PI) film was prepared with the imidization of PAAS and reduction of graphene oxide. Owing to the excellent mechanical properties of the infiltrated PI, the hardness and modulus of the rGO/PI film were as high as 0.9 GPa and 9.3 GPa, respectively. In addition, the rGO/PI film was highly conductive, with an electrical conductivity of 446 S/m, because of the well-connected electrical pathways of the highly loaded and aligned graphene sheets.

Extraction of Nanochitin from Marine Resources and Fabrication of Polymer Nanocomposites: Recent Advances.

Industrial sea food residues, mainly crab and shrimp shells, are considered to be the most promising and abundant source of chitin. In-depth understanding of the biological properties of chitin and scientific advancements in the field of nanotechnology have enabled the development of high-performance chitin nanomaterials. Nanoscale chitin is of great economic value as an efficient functional and reinforcement material for a wide range of applications ranging from water purification to tissue engineering. The use of polymers and nanochitin to produce (bio) nanocomposites offers a good opportunity to prepare bioplastic materials with enhanced functional and structural properties. Most processes for nanochitin isolation rely on the use of chemical, physical or mechanical methods. Chitin-based nanocomposites are fabricated by various methods, involving electrospinning, freeze drying, etc. This review discusses the progress and new developments in the isolation and physico-chemical characterization of chitin; it also highlights the processing of nanochitin in various composite and functional materials.

Construction of hierarchical functionalized black phosphorus with polydopamine: A novel strategy for enhancing flame retardancy and mechanical properties of polyvinyl alcohol

As a rising star of two-dimensional (2D) materials, single or few-layer black phosphorus (BP) possess great potential as nanofiller in fabricating polymer nanocomposites, due to its thermodynamic stability, nano-size effect and structural characteristics. Herein, few-layer BP nanosheets were scalable exfoliated via solvent-thermal method, the Lithium ion intercalation was achieved during this procedure. Follow by a polydopamine (PDA) encapsulated BP sandwich nanostructure was developed by oxidation–reduction strategy, which improved the air stability of few-layer BP and its interfacial compatibility with polymer matrix. As could be expected, the PDA encapsulated BP (BP-PDA) can effectively enhance the mechanical properties and flame retardancy of polyvinylalcohol (PVA) nanocomposite films. For instance, the PVA/BP-PDA5.0 nanocomposite film loaded with 5 wt% BP-PDA exhibited 57.2% maximum decrease in peak heat release rate and 47.9% maximum reduction in total heat release. Meanwhile, while the BP-PDA loading achieved 2 wt%, PVA/BP-PDA2.0 nanocomposite film revealed an 81.1% increase in the tensile strength. In particular, onaccountofdual protection of the PDA encapsulation and polymer matrix embedding, the air stability of BP in PVA matrix was significantly improved. As an evidence, the ratio of Ag1/Ag2 in Raman spectra of BP-PDA decreased from the initial 0.72 to 0.62, even after exposed to air for five months, indicating a low level of oxidation. This work provides a novel strategy for scalable exfoliation and functionalization of BP, and enables a wide range of potential applications of BP in polymer nanocomposites.

Polymer-inorganic hybrid colloids for ultraviolet-assisted direct ink write of polymer nanocomposites

Inorganic-polymer hybrid colloids present a modular and tunable route to fabricate polymer nanocomposites from low viscosity precursors; however, their use in additive manufacturing remains limited. This manuscript describes photocurable “hybrid colloids” to enable layered fabrication of elastomeric nanocomposites, i.e., combination of continuous-phase photocrosslinking chemistry with hybrid colloids of water-dispersible silica nanoparticles and styrene-butadiene rubber (SBR) latex particles. Varying the relative concentrations of polymeric and inorganic particles afforded precise tuning of filler loading in the final nanocomposite and introduced a bimodal particle size distribution with desirable rheological behavior for extrusion-based additive manufacturing. Specifically, ultraviolet-assisted direct ink write (UV-DIW) processing of the photocurable hybrid colloid pastes generated free-standing green bodies, which contained a combination of SBR and silica nanoparticles. Subsequent drying of the green bodies allowed SBR particle coalescence and penetration through the scaffold and surrounding the silica nanoparticles, which yielded a semi-interpenetrating network (sIPN) nanocomposite. Facile tuning of silica concentrations in the hybrid colloid enabled tuning of both the colloidal ink rheology and mechanical properties of the final sIPN nanocomposites to achieve additive manufacturing of silica-SBR nanocomposites with ultimate tensile strains exceeding 300 % and ultimate tensile strengths above 10 MPa.