Article

Polymer Data Handbook

Authors:
To read the full-text of this research, you can request a copy directly from the author.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the author.

... Considering the density measurements, the experimental results are in good agreement with the values in the literature [33]. The density increases with increasing sulfur content and hence the crosslinking degree. ...
... The values of thermal diffusivity, thermal conductivity and specific heat capacity obtained from the LFA analysis are in agreement with those reported in the literature [33]. No significant differences are observed within the prepared samples, leading to the conclusion that the crosslinking density, in the range studied, does not influence the thermal properties of the samples. ...
... Crosslinking The values of thermal diffusivity, thermal conductivity and specific heat capacity obtained from the LFA analysis are in agreement with those reported in the literature [33]. No significant differences are observed within the prepared samples, leading to the conclusion that the crosslinking density, in the range studied, does not influence the thermal properties of the samples. ...
Article
Full-text available
Elastocaloric cooling is recognized as a promising alternative to modern vapor-compression cooling systems, which often rely on environmentally hazardous refrigerants. Natural rubber (NR), a well-known renewable resource, stands out among elastomers exhibiting elastocaloric behavior due to a peculiar combination of nontoxicity, low cost, softness, long-life fatigue and high caloric power. Despite these properties, research on the refrigeration potential of NR is still in its early stages, and several aspects require attention. This work investigates, for the first time, the effect of crosslinking density on the elastocaloric properties of NR. Samples with three different crosslinking densities (2.9, 4.0 and 5.2 mol·10−4/cm3) were produced by internal compounding and hot pressing, and thermo-mechanically characterized. The assessment of the elastocaloric effect of the produced samples revealed that reducing the crosslinking degree significantly enhanced the elastocaloric properties. To compare the cooling capacity of the samples, a qualitative coefficient of performance (COPmat) was evaluated as the ratio between extracted thermal energy and deformational work per unit volume. The results highlight that the least crosslinked sample achieved the higher COPmat, equal to 2.4. These results underscore the significance of crosslinking density as one of the primary factors to be considered to enhance the refrigeration potential of NR.
... We searched each literature source for that par-ticular polymer sample's properties (density and T g , see below). When the source did not provide this information, we used a typical value for that polymer from a different literature source, a reference book, [36][37][38][39] or an online resource. [40][41][42] We included diffusivity in three liquid solvents in the dataset (water, ethanol, and carbon tetrachloride) using literature values for their density and T g (ranging from -176°C to -137°C). ...
... For comparison, we collected polymer properties from a variety of sources to define an overall chemical space for polymers. [36][37][38][39][40][41][42] We only included data for bulk polymers in this space, since other types of material (e.g., composites) are not directly addressed by the predictive model. To define a chemical space for medical device-relevant polymers, we conducted a search of publicly available device summary documents (i.e., 510(k) summaries and PMA statements of safety and effectiveness in FDA's public databases). ...
Article
Additives and contaminants in polymer‐based medical devices may leach into patients, posing a potential health risk. Physics‐based mass transport models can estimate the leaching kinetics, but they require upper‐bound estimates of solute diffusivity in the polymer. Experiments to measure can be costly and time‐consuming. Alternatives to estimate exist, but they suffer from several drawbacks, such as requiring experimental data to calibrate or specialized knowledge to apply, being limited to certain polymers, or being too time‐consuming given the plethora of polymer/solute combinations in devices. Here, we leverage a large database of diffusivity measurements and apply a machine learning method—quantile random forests (QRF)—to predict bounds on for arbitrary polymer/solute combinations, using only the solute structure and readily available polymer properties (glass transition temperature and density). The most influential factors for determining are these polymer properties and several descriptors related to solute size (e.g., molecular weight ), structure, and interactions. Note that application of the model is limited to the applicability domain defined herein and polymers with relatively low fractional‐free‐volume. We demonstrate the ability of the model to predict and diffusion‐limited transport kinetics, where it compares favorably to other available methods while also overcoming the aforementioned drawbacks.
... We show in appendix A that the results are independent of the arbitrary position x 0 taken in the static meniscus and do not vary significantly with the initial position L 0 of the fiber, as long as L 0 √ 2. These parameters will henceforth be set to x 0 = 0.1 and L 0 = √ 2, as justified in appendix A. The system of partial differential equations (22)(23), supplemented by the initial solutions (29) and boundary conditions (30)(31), is solved using the direct solver MUMPS in COMSOL 5.0. Since the problem involves a moving boundary -the fiber which is lifted at a constant velocity to create the film -the domain geometry is changing with time. ...
... Commercially available silicone oils are actually mixtures of PDMS chains of different lengths (or equivalently of different molar masses), the distribution of which is peaked around the number average molar mass M n . The surface tension of silicone oil increases with the number average molar mass up to M n ∼ 10 4 g/mol, where the surface tension saturates at a constant value γ ≈ 21 mN/m [31]. Since short PDMS chains (i.e. with a molar mass less than about 10 4 g/mol) have a lower surface tension than longer chains, any spatial heterogeneity in their concentration -either due to the creation of fresh interface or to evaporation -can generate surface tension gradients. ...
Preprint
Full-text available
In this paper, we derive a lubrication model to describe the non-stationary free liquid film that is created when a vertical frame is pulled out of a liquid reservoir at a given velocity. We here focus on the case of a pure liquid, corresponding to a stress-free boundary condition at the liquid/air interfaces of the film, and thus employ an essentially extensional description of the flow. Taking into account van der Waals interactions between the interfaces, we observe that film rupture is well-defined in time as well as in space, which allows us to compute the critical thickness and the film height at the moment of rupture. The theoretical predictions of the model turn out to be in quantitative agreement with experimental measurements of the break-up height of silicone oil films in a wide range of pulling velocities and supporting fiber diameters.
... Cada uno de estos se ve afectado por diferentes variables del proceso y las propiedades del material. Las propiedades de los materiales que se utilizarán se representan en la Tabla 2.2 y se obtuvieron de fuentes bibliográficas (Harper, 1996;Mark, 2009 ...
... Las variables de decisión continuas como la Presión de Inyección x1, la Temperatura de la masa fundida x2, la Temperatura del Molde x3 y la Temperatura de expulsión x4 están dadas por ciertos valores límites que están en función del Tipo de material x6, los cuales se representan en la tabla 2.3 y se obtuvieron a través de una revisión bibliográfica (Harper, 1996;Mark, 2009) ...
... Refraction Index 1.4 [5] Thermal conductivity (W/m·K) 0.2−0.27 [6,7] Young's modulus (kPa) 360−870 [8] Poisson ratio 0.5 [9] Tensile strength (MPa) 2.24−6.7 [5,6] Hardness (Shore A) 41−43 [10,11] Hydrophobicity/contact angle ( • )~108 • ± 7 • [12] Melting Point ( • C) −49.9 to −40 [13] These unique qualities have led to the widespread use of PDMS in a variety of applications, including micropumps [14], microvalves [11], optical systems [15,16], in vitro blood studies [17,18], blood analogs [19], implants [20,21], and microfluidics [22,23]. ...
... Refraction Index 1.4 [5] Thermal conductivity (W/m·K) 0.2−0.27 [6,7] Young's modulus (kPa) 360−870 [8] Poisson ratio 0.5 [9] Tensile strength (MPa) 2.24−6.7 [5,6] Hardness (Shore A) 41−43 [10,11] Hydrophobicity/contact angle ( • )~108 • ± 7 • [12] Melting Point ( • C) −49.9 to −40 [13] These unique qualities have led to the widespread use of PDMS in a variety of applications, including micropumps [14], microvalves [11], optical systems [15,16], in vitro blood studies [17,18], blood analogs [19], implants [20,21], and microfluidics [22,23]. PDMS is the most frequently used material to fabricate biomedical microdevices, crucial for developing systems like drug delivery, clinical diagnostics, and point-of-care testing [24]. ...
Article
Full-text available
Polydimethylsiloxane (PDMS) has become a popular material in microfluidic and macroscale in vitro models due to its elastomeric properties and versatility. PDMS-based biomodels are widely used in blood flow studies, offering a platform for improving flow models and validating numerical simulations. This review highlights recent advances in bioflow studies conducted using both PDMS microfluidic devices and macroscale biomodels, particularly in replicating physiological environments. PDMS microchannels are used in studies of blood cell deformation under confined conditions, demonstrating the potential to distinguish between healthy and diseased cells. PDMS also plays a critical role in fabricating arterial models from real medical images, including pathological conditions such as aneurysms. Cutting-edge applications, such as nanofluid hemodynamic studies and nanoparticle drug delivery in organ-on-a-chip platforms, represent the latest developments in PDMS research. In addition to these applications, this review critically discusses PDMS properties, fabrication methods, and its expanding role in micro- and nanoscale flow studies.
... for nanoclays used as reinforcement (Ku et al., 2011;Ji et al., 2021;Józó et al., 2022;Majeed 350 et al., 2013;Mohanty et al., 2018). However, the E values are still lower than those obtained 351 for synthetic polymers (Mark, 1999). 352 353 Table 3. ...
... The increase of E indicates that the reinforced TPS sheets are stiffer than the control (0% of AFs); also, the obtained values are comparable in magnitude to those found in the literature for nanoclays used as reinforcement (Ku et al., 2011;Ji et al., 2021;Józó et al., 2022;Majeed et al., 2013;Mohanty et al., 2018). However, the E values are still lower than those obtained for synthetic polymers (Mark, 1999). Another factor that influences the UTS values of reinforced TPS sheets is the difference in the tensile strength between fibers and the TPS matrix. ...
... In addition, the maximum DTG for both matrices was around 294 C. Regarding the DSC analysis of the PLLA matrices, still in the absence of reinforcement, they showed melting temperatures ranging from 169 to 173 C, glass transition temperatures around 53-54 C and crystallinity from 49% to 54% which is in line with literature values for high molar masses PLLA (Table 1). 33,34 In contrast to synthetic fibers such as glass fabrics, flax fibers exhibit an irregular and non-uniform structure, contributing to irregularities and voids within the composite material. The inherent irregularities in flax fibers can cause disruptions in the resin flow during the injection process, leading to the formation of voids and unfilled areas. ...
... Regarding thermal properties, T g of PLLA/flax (UD) matrix increased from 3 C and its T m decreased from 173 to 168 C, phenomena which were observed in the literature. 33,34 The T g of PLLA/flax(TW) matrix did not change drastically after 30 days, however the T m was affected with a decrease from 170 to 160 C ( Table 4). The highest number of voids in the PLLA/flax(TW) composite increased the exposed area of the plate to UV irradiation which may cause more degradation to the matrix than in PLLA/flax(UD) one. ...
Article
Full-text available
Development of biocomposites is becoming a necessity due to environmental concerns. Polylactide is a matrix of choice, regarding its bio‐sourced and compostable nature along with its mechanical properties. In this study, poly(L‐lactide)/flax biocomposites were produced using thermoplastic resin transfer molding (TP‐RTM) in one step process from the monomer, affording sustainable and fully compostable composite materials. The polymerization of L‐lactide (L‐LA) monomer was promoted by tin octoate, affording poly(L‐lactide) (PLLA) matrices displaying monomer conversions superior to 96% and mass‐average molar masses above 140,000 g/mol. Flax fibers were used as received without any functionalization which is usually conducted to prevent the hydroxyl groups to conduct side reactions. Mechanical testing revealed bending modulus of 9.3 GPa and bending strength of 177 MPa comparable to existing literature values for PLLA/flax composites produced by other techniques. Digital microscopy analysis provided insights into impregnation quality and void characterization within the composites. In addition, the durability of these biocomposites was also evaluated via accelerated aging tests. Highlights PLLA/flax biocomposites were produced by TP‐RTM for the first time. In situ polymerization of the PLLA matrix associated with non‐functionalized flax fabrics was conducted. Bending properties were found in line with those of PLLA/flax composites produced by compression molding. Aging tests under UV at 50°C of PLLA/flax biocomposites were conducted.
... Ce type de polarisation a une durée de vie dans le même domaine que celles associées à la polarisation d'orientation, pouvant varier de la microseconde à des périodes beaucoup plus longues. Un exemple particulier de ce mécanisme est la polarisation interfaciale de Maxwell-Wagner et Sillard[50] qui est typique des systèmes hétérogènes. Cela peut également se traduire par l'accumulation de charges à l'interface entre les différents composants du diélectrique, comme au niveau des joints de grain, par exemple. ...
Thesis
Full-text available
الخلاصة : في هذه الدراسة ، تم فحص زجاج الفوسفات ذو التركيبة التالية Na2ZnP2O7 لمعرفة سلوك التبلور غير متساوي الحرارة والمرحلة التي يتبلور فيها الزجاج. تُستخدم عمليات حيود الأشعة السينية (DRX) والتحليل الحراري التفاضلي (ATD)لدراسة الطور البلوري والمعلمات الحركية المرتبطة به في عينات الزجاج، على التوالي. يشير مخطط حيود الزجاج المركب إلى بنية زجاجية غير متبلورة دون مرحلة بلورية إضافية. بالإضافة إلى ذلك، تظهر عينة الزجاج المعالجة بالحرارة تبلور المرحلة البلورية Na2ZnP2O7 تمت دراسة حركية التبلور والمعلمات المرتبطة بها لزجاجNa2ZnP2O7 باستخدام نماذج مختلفة. تم استنتاج أس أفرامي لفهم تشكل خلية الوحدة للبلورة ونمو المراحل البلورية المختلفة التي تكونت عن طريق المعالجة الحرارية للزجاج. يؤكد تغيير الأس الأفرامي المحلي مع جزء الحجم المتبلور أن عملية التبلور تحدث عن طريق تشكل خلية وحدة بلورية حجمية ( نواة) ، حيث يليها النمو ثلاثي الأبعاد. في المقابل، تم تصنيع سلسلة من زجاج فوسفات الزنك المطعمة بأيونات معادن انتقالية مختلفة ذات تركيب 〖 Na〗_2 Zn_((1-x) ) M_x P_2 O_7حيث M = Ni أو Co ،بنسب مختلفة 5 % 2% 1% في المول و تمت دراسة الجزء التخيلي لثابت العزل الكهربائي للنظام باستخدام حواجز عازلة موضوعة على جانبي العينة، في نطاق درجة الحرارة والتردد من 273 إلى 473 كلفن و-210هرتز إلى 1 ميجا هرتز، على التوالي، من خلال التحليل الطيفي للممانعة. بالإضافة إلى ذلك، تمت مناقشة المعلمات الديناميكية الحرارية المحسوبة، مثل طاقة التنشيط الحرة (ΔF)، والمحتوى الحراري للتنشيط (ΔH)، وانتروبيا التنشيط (ΔS)، بناءً على التركيب وطبيعة كاتيون المنشطات. الكلمات الدالــــة : زجاج الفوسفات، حركية التبلور، التحليل الحراري التفاضلي، مطيافية المقاومة المركبة، الخواص العازلة، المحتوى الحراري، الإنتروبي،االانتالبي. Abstract: In the present investigation, a glass of the composition Na2ZnP2O7 is studied for its non-isothermal crystallization behaviour and the phase into which the glass crystallizes. X-ray diffraction (XRD) and differential thermal analysis (DTA) processes are used to study the crystalline phase and its associated kinetic parameters for the glass sample, respectively. The diffractogram of the as-synthesized glass indicates an amorphous glassy structure without an additional crystalline phase. Moreover, the heat-treated glass sample shows the crystallization of the Na2ZnP2O7 crystalline phase. The crystallization kinetics and associated parameters of Na2ZnP2O7 glass were deeply delved into, with various models. Avrami exponents are deduced to understand the nucleation and growth of different crystalline phases formed by glass heat treatment. The change in the local Avrami exponent with the crystallized volume fraction confirms that the crystallization process occurs through volume nucleation, mainly with 3D growth. In other hand, a series of zinc phosphate glass doped with different transition metal ions of the composition Na_2 Zn_((1-x) ) M_x P_2 O_7 (where M = Ni and Co), with x = 2 and 5 mol %, were synthesized. The imaginary part of the dielectric constant properties of the system has been investigated with insulating barriers placed on both sides of the sample, in the temperature and the frequency range 273–473 K and 10-2 Hz–1MHz, respectively, by means of impedance spectroscopy. Moreover, the calculated thermodynamic parameters, such as the free energy of activation (ΔF), the enthalpy of activation (ΔH), and the entropy of activation (ΔS), were discussed as function composition and nature of cation doping. Keywords: Phosphate glasses, crystallization kinetics, Differential Thermal Analysis, Complex Impedance Spectroscopy, dielectric properties, enthalpy, entropy Résumé : Dans la présente étude, un verre de composition Na2ZnP2O7 est étudié pour son comportement de cristallisation non isothermique et la phase dans laquelle le verre se cristallise. Les processus de diffraction des rayons X (XRD) et d'analyse thermique différentielle (DTA) sont utilisés pour étudier la phase cristalline et ses paramètres cinétiques associés aux échantillons de verre, respectivement. Le diffractogramme du verre synthétisé indique une structure vitreuse amorphe sans phase cristalline additionnelle. De plus, l'échantillon de verre traité thermiquement montre la cristallisation de la phase cristalline Na2ZnP2O7. La cinétique de cristallisation et les paramètres associés du verre Na2ZnP2O7 ont été approfondis, avec divers modèles. Les exposants d'Avrami sont déduits pour comprendre la nucléation et la croissance des différentes phases cristallines formées par le traitement thermique du verre. Le changement de l'exposant local d'Avrami avec la fraction de volume cristallisé confirme que le processus de cristallisation se produit par nucléation de volume, principalement avec une croissance en 3D. En revanche, une série de verres de phosphate de zinc dopés avec différents ions de métaux de transition de composition Na_2 Zn_((1-x) ) M_x P_2 O_7 (où M = Ni et Co), avec x = 2 et 5 % mol, ont été synthétisés. La partie imaginaire des propriétés de la constante diélectrique du système a été étudiée avec des barrières isolantes placées des deux côtés de l'échantillon, dans la plage de température et de fréquence de 273 à 473 K et de 10-2 Hz à 1 MHz, respectivement, par le biais de la spectroscopie d'impédance. De plus, les paramètres thermodynamiques calculés, tels que l'énergie libre d'activation (ΔF), l'enthalpie d'activation (ΔH) et l'entropie d'activation (ΔS), ont été discutés en fonction de la composition et la nature du cation dopant. Mots clés : Verres de phosphate, cinétique de cristallisation, Analyse Thermique Différentielle, Spectroscopie d'Impédance Complexe, propriétés diélectriques, enthalpie, entropie.
... The spectrum of the recovered LDPE exhibits all the characteristic absorption bands expected for LDPE [33,34]. The bands at around 2915 cm −1 and 2848 cm −1 correspond to Solution Before processing After processing Percent recovery Solvent 50 ml 45 ml 90 Polyethylene 0.2565 gr 0.2554 gr 100 Table 5 Recovery rate of solvent and polyethylene after distillation process the asymmetric and symmetric C-H stretching vibrations of the methylene (-CH2-) groups, respectively. ...
Article
Full-text available
Aseptic packaging refers to cartons made of paper, polyethylene, and aluminum layers that provide sterile packaging for products such as beverages, but recycling these multilayer laminates poses multiple challenges. Conventional recycling relies on hydropulping, which partially destroys and limits material recovery. This study demonstrates a new closed-loop process for recycling aseptic packaging through a chemical method without hydropulping. In this method, a solvent mixture of gasoline: xylene: toluene (50:25:25, v/v) is shown for the first time to completely dissolve the polyethylene and free the other layers. The dissolved polymer is distilled and converted back to pure LDPE. Dissolution efficiency is compared using different volumetric ratios and the effects of parameters including solid-to-liquid ratio, stirrer speed, time, and processing temperature are examined. By circumventing the paper pulping process and its associated issues and problems, the dissolution-distillation process enables reuse of all components of aseptic packaging in their original form. This approach, aided by solvent recycling, enables sustainable multilayer laminate recycling.
... The most commonly used polymer for packaging products is low-density polyethylene (LDPE), which presents the additional advantage of a low price/satisfactory product quality ratio [1]. LDPE is a flexible, waxy, transparent, thermoplastic [2] that loses its elastic properties after prolonged exposure to sunlight and moisture. Polyethylene films have low permeability to water vapour, are resistant to acids and alkalis, and can withstand low temperatures, making them a preferred option for packaging applications [3]. ...
Article
Full-text available
Plastic film, also known as low-density polyethylene (LDPE), poses serious environmental challenges due to mass production, short life cycle, and poor waste management. The main aim of this paper was to examine the suitability of using agricultural waste film as a binder in construction composites instead of the traditional cement slurry. Molten at temperatures of around 120-150 °C wastes was mixed with fine sand and gravel aggregate as filler. Twelve samples consisting of different mixtures were produced-F20, F25, F30, F35, F40, F45, F50, F60, F70, F80, F90, and F100-where a given number indicates the weight ratio of film waste to aggregate used. The composites were subjected to various tests, including volumetric density, compressive strength, and flexural strength. The vol-umetric density () of the composites decreased with increasing amounts of waste. Composites containing 100% recyclate (F100) depicted density, = 0.74 g/cm 3 , was 50.7% lower than for a composite that contained 20% recyclate (F20). The highest soakability was recorded in F20 (2.19%). Subsequently, the absorbency tested in composites decreased with increasing recyclate content. Compression strength (σcomp) was highest for F40 (σcomp = 39.46 MPa). In contrast, F20 had the lowest recorded compressive strength value (σcomp = 11.13 MPa) and was 71.8% lower than F40. F70 had the highest recorded flexural strength value (σflex = 27.77 MPa). The other composites showed lower strength for higher amounts of recyclate and the amount of sand. SEM imaging proved that the contact zone between the aggregate grains and the bonding phase of the recycled film was consistent, with no anomalies, cracks, or voids. The results prove that LDPE film waste is suitable for use as a binder in building composites. However, appropriately selecting proportions of the re-cyclate, sand, and gravel aggregate is crucial to obtain a composite with technical parameters similar to those of cementitious composites.
... Heating was performed between 30 • C and 290 • C at a ramp rate of 10 • C/min. The following data were used for the calculation of the crystallinity degree (Xc): the heat of fusion of PPS is 76.5 J/g [42], the heat of fusion of PP is 165 J/g [43], and the resin content of GF/PPS composites is 40%, while GF/PP composites have a resin content of 30%, as indicated in Table 1. ...
Article
Full-text available
Filament winding is a widely used out-of-autoclave manufacturing technique for producing continuous fiber-reinforced thermoplastic composites. This study focuses on optimizing key filament winding process parameters, including heater temperature, roller pressure, and winding speed, to produce thermoplastic composites. Using Box–Behnken response surface methodology (RSM), the study investigates the effects of these parameters on the compressive load of glass fiber-reinforced polypropylene (GF/PP) and polyphenylene sulfide (GF/PPS) composite cylinders. Mathematical models were developed to quantify the impact of each parameter and optimal processing conditions were identified across a wide temperature range, enhancing both manufacturing efficiency and the overall quality of the composites. This study demonstrates the potential of thermoplastic filament winding as a cost-effective and time-efficient alternative to conventional methods, addressing the growing demand for lightweight, high-performance, out-of-autoclave composites in industries such as aerospace, automotive, and energy. The optimized process significantly improved the performance and reliability of filament winding for various thermoplastic applications, offering potential benefits for industrial, aerospace, and other advanced sectors. The results indicate that GF/PPS composites achieved a compressive load of 3356.99 N, whereas GF/PP composites reached 2946.04 N under optimized conditions. It was also revealed that operating at elevated temperatures and reduced pressure levels enhances the quality of GF/PPS composites, while for GF/PP composites, maintaining lower temperature and pressure values is crucial for maximizing strength.
... In this context, the polydimethylsiloxane rubber (PDMS) appears as a potential mechanocaloric material. PDMS is a well-studied polymer for several applications, such as medicine, food industry, toxicity tests, microfabrication [25]. From a physico-chemical point of view, PDMS is an elastomer, i.e., composed of long-chain molecules with freely rotating links, weak secondary forces between the molecules, and cross-links able to form a three-dimensional network [26]. ...
Preprint
The barocaloric effect is still an incipient scientific topic, but it has been attracting an increasing attention in the last years due to the promising perspectives for its application in alternative cooling devices. Here, we present giant values of barocaloric entropy change and temperature change induced by low pressures in PDMS elastomer around room temperature. Adiabatic temperature changes of 12.0 K and 28.5 K were directly measured for pressure changes of 173 MPa and 390 MPa, respectively, associated with large normalized temperature changes (~70 K GPa-1). From adiabatic temperature change data, we obtained entropy change values larger than 140 J kg-1 K-1. We found barocaloric effect values that exceed those previously reported for any promising barocaloric materials from direct measurements of temperature change around room temperature. Our results stimulate the study of the barocaloric effect in elastomeric polymers and broaden the pathway to use this effect in solid-state cooling technologies.
... The observed dependence is linear and the linear thermal expansion coefficient can be directly extracted from this measurement, yielding a value = (3.4 ± 0.3) · 10 -4 °C -1 , in good agreement with the value reported in literature 28 . One can easily determine the amount of biaxial expansion/compression of the substrate directly from the temperature = · ( − 25 ℃). ...
Preprint
Since their discovery single-layer semiconducting transition metal dichalcogenides have attracted much attention thanks to their outstanding optical and mechanical properties. Strain engineering in these two-dimensional materials aims to tune their bandgap energy and to modify their optoelectronic properties by the application of external strain. In this paper we demonstrate that biaxial strain, both tensile and compressive, can be applied and released in a timescale of a few seconds in a reproducible way on transition metal dichalcogenides monolayers deposited on polymeric substrates. We can control the amount of biaxial strain applied by letting the substrate expand or compress. To do this we change the substrate temperature and choose materials with a large thermal expansion coefficient. After the investigation of the substrate-dependent strain transfer, we performed micro-differential spectroscopy of four transition metal dichalcogenides monolayers (MoS2, MoSe2, WS2, WSe2) under the application of biaxial strain and measured their optical properties. For tensile strain we observe a redshift of the bandgap that reaches a value as large as 95 meV/% in the case of single-layer WS2 deposited on polypropylene. The observed bandgap shifts as a function of substrate extension/compression follow the order MoSe2 < MoS2 < WSe2 < WS2. Theoretical calculations of these four materials under biaxial strain predict the same trend for the material-dependent rates of the shift and reproduce well the features observed in the measured reflectance spectra.
... The thickness of the slabs was varied between 20 mm and 30 mm with no changes in the observed dynam-ics. The Young's modulus and Poisson's ratio for PDMS were estimated as 1 MPa and 0.46 respectively, from shear [28] and bulk modulus values reported in the literature [29]. ...
Preprint
Stick-slip, manifest as intermittent tangential motion between two solids, is a well-known friction instability that occurs in a number of natural and engineering systems. In the context of adhesive polymer interfaces, this phenomenon has often been solely associated with Schallamach waves, which are termed slow waves due to their low propagation speeds. We study the dynamics of a model polymer interface using coupled force measurements and high speed \emph{in situ} imaging, to explore the occurrence of stick-slip linked to other slow wave phenomena. Two new waves---slip pulse and separation pulse---both distinct from Schallamach waves, are described. The slip pulse is a sharp stress front that propagates in the same direction as the Schallamach wave, while the separation pulse involves local interface detachment and travels in the opposite direction. Transitions between these stick-slip modes are easily effected by changing the sliding velocity or normal load. The properties of these three waves, and their relation to stick-slip is elucidated. We also demonstrate the important role of adhesion in effecting wave propagation.
... This is why it is not possible to measure T g for PS film thinner than 10 nm by this approach, due to the noise. For the data shown in Figure 3, the measured value of T g is 364 ± 1.5 K, reduced in comparison to the value 373 K that was measured for a 120 nm thick film, and which is also the value reported in the litterature for the bulk T g [39]. Figure 4 shows all T g s of the different samples configurations measured in this study, as a function of the overall film thickness. ...
Preprint
We present an investigation of the effect of the interaction between a thin polystyrene film and its supporting substrate on its glass transition temperature (Tg). We modulate this interaction by depositing the film on end-tethered polystyrene grafted layers of controlled molecular parameters. By comparing Tg measurements versus film thickness for films deposited on different grafted layers and films deposited directly on a silicon substrate, we can conclude that there is no important effect of the film-subtrate interaction. Our interpretation of these results is that local orientation and dynamic effects substantial enough to influence Tg cannot readily be obtained by grafting prepolymerized chains to a surface, due to intrinsic limitation of the surface grafting density.
... The layers were then assembled on a hot press set at 110°C, slightly above the glassy transition temperature of PS (≈100°C). [39] Exposing polymers like PS to such conditions gives them rubber-like properties, which translates into a slight softening of the material that allows the layers to bond to each other, [40] allowing the production of a device solely using the PS slabs ( Figure 2B). ...
Article
Full-text available
Tumor‐on‐chip (ToC) is crucial to bridge the gap between traditional cell culture experiments and in vivo models, allowing to recreate an in vivo‐like microenvironment in cancer research. ToC use microfluidics to provide fine‐tune control over environmental factors, high‐throughput screening, and reduce requirements of samples and reagents. However, creating these microfluidic devices requires skilled researchers and dedicated manufacturing equipment, making widespread adoption cumbersome and difficult. To address some bottlenecks and improve accessibility to ToC technology, innovative materials and fabrication processes are required. Polystyrene (PS) is a promising material for microfluidics due to its biocompatibility, affordability, and optical transparency. Herein, a fabrication process based on direct laser writing on thermosensitive PS, allowing the swift and economical crafting of devices with easy pattern alterations, is presented. For the first time, a device for cell culture fabricated only by PS is presented, allowing customizing and optimization for efficient cell culture approaches. These biochips support 2D and 3D cultures with comparable viability and proliferation kinetics to traditional 96‐well plates. The data show that gene and protein silencing efficiencies remain consistent across both chip and plate‐based cultures, either 2D culture or 3D spheroid format. Although simple, this approach might facilitate the use of customized chip‐based cancer models.
... PCL's biodegradability is another critical feature, with its degradation rate influenced by factors like molecular weight, environmental conditions, and crystallinity. [220,221] For example, PCL can exhibit a notable crystallinity of up to 69%, [222] and its degradation initiates from its amorphous phase, potentially leading to an increase in crystallinity. [223] The reduction in molecular weight occurs due to the cleavage of ester bonds, contributing to its biodegradation. ...
Article
Full-text available
3D printing, also known as additive manufacturing, holds immense potential for rapid prototyping and customized production of functional health‐related devices. With advancements in polymer chemistry and biomedical engineering, polymeric biomaterials have become integral to 3D‐printed biomedical applications. However, there still exists a bottleneck in the compatibility of polymeric biomaterials with different 3D printing methods, as well as intrinsic challenges such as limited printing resolution and rates. Therefore, this review aims to introduce the current state‐of‐the‐art in 3D‐printed functional polymeric health‐related devices. It begins with an overview of the landscape of 3D printing techniques, followed by an examination of commonly used polymeric biomaterials. Subsequently, examples of 3D‐printed biomedical devices are provided and classified into categories such as biosensors, bioactuators, soft robotics, energy storage systems, self‐powered devices, and data science in bioplotting. The emphasis is on exploring the current capabilities of 3D printing in manufacturing polymeric biomaterials into desired geometries that facilitate device functionality and studying the reasons for material choice. Finally, an outlook with challenges and possible improvements in the near future is presented, projecting the contribution of general 3D printing and polymeric biomaterials in the field of healthcare.
... Common polymers used for shielding materials are[19]: Poly Aniline, Poly Vinyl Alcohol, Poly Vinyl Chloride, Poly Ethylene, Poly Propylene, Poly Lactic Acid etc. Among all the conducting polymers, Polyaniline (PANI) belonging to the semi-flexible rod polymer family has been investigated extensively because of several unique properties like: good processability, high stability, soluble in various solvents, simplicity in preparation, inexpensive monomer, light weight ...
Conference Paper
Full-text available
Today's fast growing wireless world faces one new type of problem, Electromagnetic (EM) pollution due to advancements and penetration of communication technologies. This disturbs the proper functioning of electronic devices due to EM Interference (EMI) and also harmful for human health at some extent. Therefore, EM Compatibility (EMC) becomes necessary for electronic devices. Another problem faced by the world, is environment pollution created by biomass waste. Researchers have shown very much interest in the fabrication of EMI shields made from Bio composite materials to minimize the effect of above mentioned two types of pollutions. The Bio composite shields can be made from blending and mixing of polymers, bio char and highly conductive nano fillers. The shielding effectiveness (SE) of Bio composite shields is mainly function of conductivity, thickness, dielectric properties of shield and frequency of EM waves incident on shield. The S-parameters of shield can be measured by standard waveguide method and shielding effectiveness can be calculated. This paper presents the simulations of S-parameters of shield using CST microwave studio simulator for the frequencies from 8 GHz to 12 GHz i.e. X band. The SE is calculated from S-parameters and effect of thickness and conductivity of shield on SE is analyzed and discussed.
... The engineering stress vs strain curves and corresponding camera images indicated that the perforated composites featured elastomeric behavior, with Young's moduli of $0.6 MPa and breaking strains of $700% comparable to those of analogous composites without perforation (supplementary material Fig. 2 and supplementary material Table I). [24][25][26][27][28] The local optical microscopy images showed that the perforated composites' metal layers contained round holes surrounded by abutting Cu domains without any applied strain but contained oval holes surrounded by separated Cu domains upon the application of strain, indicating that the previously reported operating mechanism was maintained [ Fig. 2(c)]. [24][25][26] These experiments demonstrated the straightforward fabrication of perforated composite materials with large areas, robust mechanical properties, and reconfigurable surface microstructures. ...
Article
Full-text available
Advanced thermal management technologies represent an important research frontier because such materials and systems show promise for enhancing personal physiological comfort and reducing building energy consumption. These technologies typically offer the advantages of excellent portability, user-friendly tunability, energy efficiency, and straightforward manufacturability, but they frequently suffer from critical challenges associated with poor breathability, inadequate wash stability, and difficult fabric integration. Within this broader context, our laboratory has previously developed heat-managing composite materials by drawing inspiration from the color-changing skin of the common squid. Herein, we describe the design, fabrication, and testing of breathable, washable, and fabric-integrated variants of our composite materials, which demonstrate state-of-the-art adaptive infrared properties and dynamic thermoregulatory functionalities. The combined findings directly advance the performance and applications scope of our bioinspired thermoregulatory composites and ultimately may guide the incorporation of desirable multifunctionality into other wearable technologies.
... At the end of the reaction, the polymer can be recovered by precipitation or lyophilization. Polymers such as polyacrylic acid are commonly made by solution polymerization (Mark, 1999), (Ohara, 2011). ...
Article
Full-text available
A model is proposed to estimate the dosage rate of monomers in a polymerization reaction. The model consists of a bimodal Gamma probability distribution function for describing the conversion velocity of monomers in a flask polymerization reactio (laboratory scale). The function of conversion percentage of monomers (the integral of the conversion velocity of monomers) is correlated with the experimental data. From this function, the conversion percentage of monomers is developed for a polymerization reaction, where monomers are added with a suitable dosage rate. The dosage rate of monomers is determined from a minimization procedure applied to the mean square deviation between the conversion percentage of the fast and slow monomers. In this way, the dosage rate of monomers is estimated to define the polymerization experiment on micro-plant scale. From these experiments, the resulting polymeric product (with 1 L or 5 L scale) is homogeneous and without residual monomers. Keywords: Terpolymers, synthesis, Gamma distribution, dosage rate, micro plant
... For the DSC measurements, the glass transition temperature (T g ), the melting temperature (T m ), the melting enthalpy (ΔH m ), the enthalpy of crystallisation (ΔH c ) and the crystalline fraction (X c ) were determined. We calculated the crystalline fraction (X c ) with Eq. (1), where ΔH m is the enthalpy of crystallisation of the first heating curve, ΔH 100% is the enthalpy of the melting if the polymer is 100 % crystalline, which for PA6 is ΔH 100% =188 J/g [37], and α is the flame retardant content. ...
... It can be dissolved in acetone and other organic solvents and has low toxicity. [55][56][57] By virtue of these properXes, PECH paves the way for applicaXons requiring flexibility, durability, and recyclability. The Ni97Co3 AMR microparXcles with a volume raXo of 50% or [Co/Cu]50 GMR microflakes with a concentraXon of 40 mg/mL were incorporated into the elastomer binder to produce printable composites. ...
Article
Full-text available
We have developed recyclable printed magnetoresistive sensors using giant magnetoresistive (GMR) microflakes and anisotropic magnetoresistive (AMR) microparticles as functional fillers, with polyepichlorohydrin (PECH) as the elastomer binder. Under their respective...
... Як видно з рис. 5 склування аморфної складової чистого ПХТФЕ спостерігається в температурному інтервалі 45 ÷ 50 С, що цілком узгоджується із літературними даними [15]. Внесення до складу систем 0,96% ТРГ та 0,95% ТРГ/30%SiO2 призводить до пониження температур склування полімерної матриці, що свідчить про її розрихлення, що одночасно зі збільшенням температур плавлення полімерної складової (рис. ...
Article
Full-text available
Polymeric nanocomposites based on polychlorotrifluoroethylene (PCTFE) with a low content of dispersed thermally expanded graphite TRG and modified filler TRG/SiO2, characterized by high electrophysical properties, were obtained. The features of the electronic structure of the composite surface have been investigated. The regularities of changes in the electrophysical properties of the composites depending on the content of fillers and temperature have been established. On the basis of studies and comparative analysis of the thermophysical properties (specific heat capacity cp, temperature coefficient of linear expansion a) of the systems, the influence of the structural morphological state of the components and their concentration, the level of interfacial interaction on the physical properties of nanocomposites have been investigated.It has been established that the modified nanofiller is more active towards the polymer matrix than the unmodified one. The composites exhibit a double effect of the modified nanofiller on the matrix structure, which consists in the formation of a powerful crystal structure in the zones of influence of the nanofiller and amorphization of the polymer matrix in the peripheral zones. It has been found that the amorphization of the matrix results in a decrease in the area of temperature reflexes peaks on the temperature dependences of the specific heat capacity and a change in the absolute value of the temperature coefficient of linear expansion with an increase in the concentration of the modified TRG.
... [38][39][40] Recent studies have achieved an antifouling to low-surfacetension liquids by cleverly designing non-fluoroalkyl groups (─CH 3 and ─CH 2 ), overcoming the simple superhydrophobicity of previous studies on pure water, salt water, or ethylene glycol with high surface tension ( ≥ 72.8 mN m −1 or = 47.7 mN m −1 ). [41,42] However, due to the selfpolymerization of short-chain silanes, the alkycompounds require to be prepared through vapor deposition, which requires more complex processing conditions than the liquid-phase reaction. [43][44][45][46] Meanwhile, the durability of the reported superhydrophobic alky compounds remains a long-standing challenge. ...
Article
Full-text available
Superhydrophobic surfaces garner tremendous research attention due to their potential applications in the fields of oil–water separation membrane, self‐cleaning, and anti‐icing systems. However, the reported superhydrophobic materials that achieve low‐surface‐tension (<60 mN m⁻¹) liquid repellency are typically prepared using perfluorinated compounds (PFCs), which pose significant risks to the natural environment and human health. Here a concept based on the excluded volume effect in polymer dilute solutions is explored to achieve a hydrophobic flexible polymer‐chain wrapping of multidimensional particles, which forms a nonadherent soft‐shell‐hard‐core structure and maintains the original structural integrity of particles. The prepared fluoro‐free super‐repellent multidimensional particles can be spray‐coated and dip‐coated on different substrates to prepare large‐scale superhydrophobic coatings, which exhibit excellent low‐surface‐tension (42.6−50 mN m⁻¹) liquid repellency superior to the reported fluoro‐free superhydrophobic materials. Benefiting from the strong interaction of super‐repellent particles with flexible polymer chains, the superhydrophobic coatings show unexpected wear resistance and durability. This first demonstration of hydrophobic polymer‐wrapped particles for repelling low‐surface‐tension liquids provides insights into next‐generation fluoro‐free superhydrophobic materials.
... where ϵ 0 represents the vacuum permittivity, ϵ r is the relative permittivity of the medium, A denotes the electrode area, and d is the separation distance [37]. When biomarker-tagged MNPs accumulate in the detection zone, they alter the effective relative permittivity (ϵ r ), leading to a measurable change in capacitance (∆C): ...
Article
Full-text available
This study presents the design and comprehensive 3D multiphysics simulation of a novel microfluidic immunosensor for non-invasive, real-time detection of pro-inflammatory biomarkers in human sweat. The patch-like device integrates magnetofluidic manipulation of antibody-functionalized magnetic nanoparticles (MNPs) with direct-field capacitive sensing (DF-CS). This unique combination enhances sensitivity, reduces parasitic capacitance, and enables a more compact design compared to traditional fringing-field approaches. A comprehensive 3D multiphysics simulation of the device, performed using COMSOL Multiphysics, demonstrates its operating principle by analyzing the sensor’s response to changes in the dielectric properties of the medium due to the presence of magnetic nanoparticles. The simulation reveals a sensitivity of 42.48% at 85% MNP occupancy within the detection zone, highlighting the sensor’s ability to detect variations in MNP concentration, and thus indirectly infer biomarker levels, with high precision. This innovative integration of magnetofluidic manipulation and DF-CS offers a promising new paradigm for continuous, non-invasive health monitoring, with potential applications in point-of-care diagnostics, personalized medicine, and preventive healthcare.
... Additionally, a noticeable divergence is observed as the temperature rises. By fitting the two branches with straight lines, the diffusion coefficients converge smoothly toward the point at 375 K, which is quite close to the experimental value of 373 K. [49] The difference between the calculated and experimental data is mainly due to the incomplete description of the second-order phase transition. The results indicate that the glass transition of PS can be quantitatively calculated from chain diffusion kinetics. ...
Article
Full-text available
The mechanisms behind the polymer glass transition, though not fully elucidated, have garnered significant attention. The Locally Correlated Lattice (LCL) theory [R. P. White, J. E. Lipson, Macromolecules 2016, 49, 3987] provides a novel perspective on free volume and establishes the relationship between polymer glass transition and free volume. In this study, we present a dynamic theoretical model based on the thermodynamic LCL theory, focusing on the kinetic evolution of free volume during polymer glass transition. Our analysis simultaneously examines the segmental diffusion coefficient, dynamic correlation length, free volume, and isobaric heat capacity. The results indicate that, upon reaching a critical temperature, heterogeneous dynamics and singular thermodynamics emerge concurrently. This study establishes a comprehensive correlation between thermodynamic singularities and dynamic inhomogeneities, offering valuable insights into the polymer glass transition process.
... where ν is the Poisson's ratio, given at 0.5 for generic PDMS [22]. E, expressed in MPa, can be estimated from Shore A measurements by several empiric approximations. ...
Article
Full-text available
Elastomers are intriguing materials for many applications, one of these being icephobic coatings. Elastic modulus and work of adhesion are the key parameters coming into play in ice detachment mechanisms, and can be related to hardness and wettability. Polydimethylsiloxane (PDMS) is widely used for anti-ice applications; however, not many works deal with the correlation between cross-linking grade, curing treatments, and icephobicity. This study focuses on PDMS (Sylgard184®) coatings, encompassing four different pre-polymer to cross-linking agent (A:B) ratios ranging from 5:1 to 30:1, and nine curing treatments. The results indicate that increasing the A:B ratio enhances hydrophobicity, softness, and icephobicity, assessed through shear stress measurements. Curing treatments primarily affect hardness and icephobicity, with longer heat treatments resulting in higher hardness and ice adhesion. All samples exhibit promising performances in lowering shear stress values, up to seven times in respect to the uncoated reference for 30:1 ratio. Additionally, a durability assessment is conducted on samples exposed to stress tests in the climatic chamber. A slight deterioration in hydrophobicity across all samples is observed and, notably, a significant hardness increase, around 13%, is experienced for the 5:1 ratio only. The samples also demonstrate an overall robust icephobicity after stress tests, and, for the 30:1 ratio, an average shear stress value four times lower than the reference is maintained. In this work, we highlight the importance of the fine-tuning of the precursors ratio and thermal treatments on the PDMS properties and durability.
... In accordance with the Flory theory [38][39][40], the average molecular weight of the chain segment between crosslinks was calculated as follows: Here M n is the average molecular weight of the polymer and V e is the effective number of chains per unit volume, which was determined as (6) where is the polymer specific volume, V 1 is the solvent molar volume, υ 2, s and υ 2, r is the volume fraction of the polymer after swelling and in the relaxed state, and χ is the polymer-solvent interaction parameter (χ = 0.49 [41]). The values of υ 2, s and υ 2, r were calculated according to the known approach described in [40]. ...
... where ∆H m is the specific enthalpy of melting, and ∆H 0 is the enthalpy of melting with 100% crystalline PA6 (188 J/g) [18]. ...
Article
Full-text available
In this study, we successfully realized the hydrolytic ring-opening co-polymerization of ε-caprolactam (CPL) and lysine derivative. A novel antibacterial modified polyamide 6 with a branched structure was obtained after the quaternization of the co-polymers. The co-polymers exhibited a significant increase in zero shear viscosity, melt index and storage modulus at the low frequency region. The quaternized co-polymers displayed thermal properties different from pure PA6 and good mechanical (tensile) properties. The antibacterial activity of the quaternized co-polymers depends on the quaternary ammonium groups’ incorporated content. At 6.2 mol% incorporation of quaternary ammonium groups, the strong antibacterial activity has been introduced to the co-polymers. As the quaternary ammonium groups approached 10.1 mol%, the antibacterial polymers demonstrated nearly complete killing of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). The above research results provided a new approach for the study of high-performance nylon.
... The capacitance (C) of the system is primarily governed by the dielectric properties of the materials between the electrodes, as described by the equation: [36] ...
Preprint
Full-text available
This study presents the design and comprehensive 3D multiphysics simulation of a novel microfluidic immunosensor for real-time, non-invasive monitoring of pro-inflammatory biomarkers in human sweat. The patch-like device, designed using COMSOL Multiphysics, integrates magnetofluidic manipulation with direct-field capacitive sensing. The sensor comprises two distinct units: an immunocomplex enhancement unit, employing a series of microcoils to optimize the binding efficiency, reaction kinetics, and homogeneity of biomarker-magnetic nanoparticle (MNP) interactions, thereby enhancing the sensor's specificity; and a layered capacitive sensing unit, designed to concentrate and detect biomarker-tagged MNPs, thus amplifying sensitivity. Simulations of the capacitive sensing unit revealed a substantial sensitivity increase of up to 42.48\% at an 85\% MNP concentration within the detection zone. These findings highlight the potential of the proposed immunosensor for efficient and precise real-time biomarker monitoring, which may facilitate early disease diagnosis and enable personalized healthcare interventions.
... 초기의 구형 입자는 개별의 입자가 흡착되어 입자 와 입자 사이의 물리적인 거리가 감소되는 응고(coagulation), 개별의 입자가 흡착된 후 새로운 크기의 구형 입자를 형성하 는 합체(coalescence) 그리고 파손(breakage)의 과정을 거쳐 응 집체(agglomerates)로 성장한다 (4) . 응집체는 0. (12) . PMMA는 화염전파속도 및 폭발압력 상승 속도가 빠르기 때 문에 (13) 불꽃 연소시 높은 화재의 위험성을 가진다. Figure 2는 PMMA 시험편 사진을 나타내며 ...
Article
Large amounts of smoke and toxic gases generated during combustion are the main causes of fire casualties and are major factors that hinder evacuation (i.e., by reducing the visibility). Since the size of the smoke particles closely influences the scattering and absorption of light, it has a direct effect on the opacity of the smoke. Therefore, it is important to determine the correlation between the particle size distribution of smoke particles and smoke opacity to ensure the safety of evacuees. In this study, the correlation between density and size distribution of smoke particles from polymethyl methacrylate (PMMA) and visibility were measured with and without flame conditions. We achieved this by setting up an ISO 5659-2 smoke density chamber, equipped with a particle measuring device (OPC), and recording the visibility changes with increasing temperature. Specific optical density and visibility secured during evacuation were compared. As the specific optical density increased, the particle concentration with a size of 0.25 - 0.3 μm decreased but the one with a size of 0.3 - 0.58 μm increased significantly. Regression analysis confirmed that 0.25 - 0.58 μm particles affected light extinction the most. The difference in visibility secured during evacuation was determined based on the number of particles and size distribution.
Article
Full-text available
Since the introduction of polydimethylsiloxane (PDMS) microfluidic devices at the beginning of the 21st century, this elastomeric polymer has gained significant attention in the engineering community due to its biocompatibility, exceptional mechanical and optical properties, thermal stability, and versatility. PDMS has been widely used for in vitro experiments ranging from the macro- to nanoscale, enabling advances in blood flow studies, biomodels improvement, and numerical validations. PDMS devices, including microfluidic systems, have been employed to investigate different kinds of fluids and flow phenomena such as in vitro blood flow, blood analogues, the deformation of individual cells and the cell free layer (CFL). The most recent applications of PDMS involve complex hemodynamic studies such as flow in aneurysms and in organ-on-a-chip (OoC) platforms. Furthermore, the distinctive properties of PDMS, including optical transparency, thermal stability, and versality have inspired innovative applications beyond biomedical applications, such as the development of transparent, virus-protective face masks, including those for SARS-CoV-2 and serpentine heat exchangers to enhance heat transfer and energy efficiency in different kinds of thermal systems. This review provides a comprehensive overview of the current research performed with PDMS and outlines some future directions, in particular applications of PDMS in engineering, including biomicrofluidics, in vitro biomodels, heat transfer, and face masks. Additionally, challenges related to PDMS hydrophobicity, molecule absorption, and long-term stability are discussed alongside the solutions proposed in the most recent research studies.
Article
Full-text available
The present study aims to evaluate thin plate-injected polypropylene (PP) composites containing short aramid fibers (AF) and graphene nanoplatelets (GNPs). The aramid fibers were manually cut to a length of 10 mm and added to the polypropylene matrix at a concentration of 10 wt.%. Additionally, GNPs were incorporated at concentrations of 0.1, 0.25, and 0.5 wt.%. Maleic anhydride grafted polypropylene (MAPP) was used at a concentration of 2 wt.% to improve the adhesion and compatibility between the polymer matrix and the fillers. Thermal analyses, tensile and flexural tests, and dynamic mechanical thermal analysis were performed, followed by statistical analysis using ANOVA and Tukey’s test. The composites demonstrated significant improvements in storage and loss moduli compared to neat polypropylene. With the addition of AF and GNPs, tensile strength increased to 46.8 MPa, which represents a 265% enhancement compared to PP. Similarly, flexural strength reached 62.4 MPa, significantly higher than the 36.73 MPa for PP, particularly for the composite containing AF and 0.25 wt.% GNPs. The results presented in this study highlight the synergistic effect of aramid fibers and GNPs on PP. These improvements make the proposed composites highly promising for a range of applications, including ballistic interlayered aramid/thin-plate laminates.
Preprint
Thin polymer films have attracted attention because of both their broad range of applications and of the fundamental questions they raise regarding the dynamic response of confined polymers. These films are unstable if the temperature is above their glass transition temperature Tg. Here, we describe freestanding thin films of centimetric dimensions made of a comb copolymer melt far from its glass transition that are stable for more than a day. These long lifetimes allowed us to characterize the drainage dynamics and the thickness profile of the films. Stratified regions appear as the film drains. We have evidence that the stability, thinning dynamics and thickness profile of the films result from structural forces in the melt. Understanding the key mechanisms behind our observations may lead to new developments in polymeric thin films, foams and emulsions without the use of stabilizing agents.
Article
Full-text available
We use ultrashort optical pulses to excite and detect vibrations of single silica spheres with a diameter of 5 μ m placed at the surface of an acoustically mismatched substrate. In addition to the photoelastic detection of picosecond longitudinal acoustic pulses propagating inside the bulk, we detect gigahertz acoustic resonances of the sphere through probe beam defocusing. The mode frequencies are in close accord with those calculated from the elastic vibrations of a free sphere. We also record a resonant enhancement in the amplitude of specific modes of two touching spheres.
Article
Full-text available
The capacity to discern and locate positions in three-dimensional space is crucial for human-machine interfaces and robotic perception. However, current soft electronics can only obtain two-dimensional spatial locations through physical contact. In this study, we report a non-contact position targeting concept enabled by transparent and thin soft electronic skin (E-skin) with three-dimensional sensing capabilities. Inspired by the active electrosensation of mormyroidea fish, this E-skin actively ascertains the 3D positions of targeted objects in a contactless manner and can wirelessly convey the corresponding positions to other devices in real-time. Consequently, this E-skin readily enables interaction with machines, i.e., manipulating virtual objects, controlling robotic arms, and drones in either virtual or actual 3D space. Additionally, it can be integrated with robots to provide them with 3D situational awareness for perceiving their surroundings, avoiding obstacles, or tracking targets.
Chapter
Superliquiphobic and superliquiphilic surfaces have attracted interest in the scientific community and industry. These are being considered for applications which require self-cleaning/anti-smudge/fingerprint resistance, anti-icing, antifogging, optical transparency, low adhesion, drag reduction in fluid flow, and anti-fouling properties.
Article
Исследована реокинетика гелеобразования систем на основе водного раствора поливинилового спирта с химическими сшивками и физическими узлами, в том числе гибридных. Для получения гидрогелей в качестве сшивающих компонентов использовали глутаровый альдегид и/или тетраметоксисилан. Установлено, что на начальном этапе гелеобразования (до достижения критической конверсии гелеобразования) эффективность процесса определяется не химической природой сшивок сетки, а концентрацией сшивающего агента. Выполнен сравнительный анализ механических свойств химических, физических и гибридных гидрогелей при разной температуре. Проведение испытаний в квазистатических условиях на одноосное сжатие и растяжение позволило выявить вклад узлов и сшивок сетки в поведение гибридных гидрогелей и их отличительные особенности.
Article
This study presents the production of polypropylene (PP) biocomposites utilizing different biomasses such as apricot kernel shell (AKS, 48% lignin), hazelnut shell (HS, 40%), walnut shell (WS, 35% lignin), and corn cob (CC, 15% lignin, 40% cellulose). The biocomposites were manufactured using a twin-screw extruder by varying the type and amount (5% to 20%) of biomass used as filler. The characterizations are done using spectral, thermal, and mechanical methods. In addition, using two different brands of PP samples the effects of crystallinity on thermal and mechanical properties of the biocomposites were examined. The composition of the biomass was important; higher lignin content (as in AKS) resulted in better compounding due to its hydrophobic behavior. Another important factor affecting the performance of the biocomposites was filler content. The optimum performance was obtained 10% content. In general, addition of the filler caused an increase in crystallinity which was detected by spectral and thermal methods.
Chapter
Recent research in the field of glassy organic ionic conductors, with a focus on aromatic polymers, has contributed to advancements in solid electrolyte technology. Central to these developments is the strategic employment of asymmetric lithium salts. This approach has led to an enhancement in ionic conduction and high lithium-ion transference in the amorphous salt phases within polymer matrices such as poly(p-phenylene oxide). Utilizing machine learning techniques has been crucial in exploring and identifying the key relationships that drive electrolyte performance. The findings from this research emphasize the significant impact of using asymmetric salts in conjunction with polymer matrices. This combination improves the efficiency and functionality of solid electrolytes, presenting new possibilities for the development of more efficient energy storage solutions.
Article
Polydimethylsiloxane (PDMS)-based organic‒inorganic composites have attracted considerable attention due to PDMS’s unique features, such as transparency, softness, biocompatibility, chemical stability, heat resistance, and insulation. To extend the lifespans of organic‒inorganic...
Article
Full-text available
Poly(ethylene terephthalate) (PET) is an important polyester utilized for a wide variety of applications such as in the manufacturing of bottles, fibers and engineering compositions. Its chemical composition depends on the use of main monomers (e.g. terephthalic acid and ethylene glycol) and comonomers (e.g. diethylene glycol and isophthalic acid) at low concentrations, defining several reaction pathways upon its degradation or (mechanical) recycling. The present work provides a detailed overview of these molecular pathways, differentiating among thermal, thermo-mechanical, thermo-oxidative, photo-oxidative, hydrolytic and enzymatic degradation reactions. Considering the lowest contaminant amount, under ideal (mechanical) recycling (lab) conditions, a wide range of functional group variations has already been revealed, specifically during consecutive polyester processing cycles. Moreover, as a key novelty, how molecular variations influence material behavior is explained, considering rheological, thermal and mechanical properties. Supported by basic life cycle analysis, it is highlighted that our future improved assessment of the mechanical recycling potential of PET must better link the molecular and material scales. Only this linkage will open the door to a well-balanced polyester waste strategy, including (i) the evaluation of the most suitable recycling technology at the industrial scale, dealing with the mitigation of contaminants, and (ii) its further adoption and design in the context of overall virgin and recycling market variation.
Article
Full-text available
The mining and steelmaking industries, while vital for economic and social development, produce and dispose of waste that contributes to environmental instability and discomfort. In this context, this study aimed to develop novel polymer composites intended for Artificial Ornamental Stone (AOS) application by incorporating iron ore tailings (IOTs), quartzite waste (QTZ), and steel slag (SS) into an epoxy (EP) matrix. The chemical, mineralogical, physical, mechanical, morphological, and thermal properties of the materials were assessed. Three waste mixtures were proposed using the Modified Andreassen Curve method, each with 35, 45, and 55 v/v% of EP. The composite properties were evaluated, showing that the composite with QTZ, SS, and 55 v/v% EP exhibited the lowest porosity (0.3%), water absorption (0.1%), and highest flexural strength (41 MPa). The composite containing the three wastes with 55 v/v% EP presented 1.0% porosity, 0.4% water absorption, and 34 MPa flexural strength. Lastly, the composite with IOTs, QTZ, and 55 v/v% EP exhibited 1.1% apparent porosity, 0.5% water absorption, and 23 MPa flexural strength. Therefore, the polymer composites developed with IOTs, QTZ, SS, and EP demonstrated suitable properties for wall cladding and countertops, presenting a potentially sustainable alternative to reduce environmental impacts from the mining and steelmaking industries.
Article
Full-text available
Thermally driven membrane processes provide an alternative method to conventional pressure driven processes to recover high quality water and manage odour from concentrated blackwater, using a low-grade heat source instead of electrical energy.
Article
Full-text available
Three-dimensional optical nanostructures have garnered significant interest in photonics due to their extraordinary capabilities to manipulate the amplitude, phase, and polarization states of light. However, achieving complex three-dimensional optical nanostructures with bottom-up fabrication has remained challenging, despite its nanoscale precision and cost-effectiveness, mainly due to inherent limitations in structural controllability. Here, we report the optical characteristics of intricate two- and three-dimensional nanoarchitectures made of colloidal quantum dots fabricated with multi-dimensional transfer printing. Our customizable fabrication platform, directed by tailored interface polarity, enables flexible geometric control over a variety of one-, two-, and three-dimensional quantum dot architectures, achieving tunable and advanced optical features. For example, we demonstrate a two-dimensional quantum dot nanomesh with tuned subwavelength square perforations designed by finite-difference time-domain calculations, achieving an 8-fold enhanced photoluminescence due to the maximized optical resonance. Furthermore, a three-dimensional quantum dot chiral structure is also created via asymmetric stacking of one-dimensional quantum dot layers, realizing a pronounced circular dichroism intensity exceeding 20°.
ResearchGate has not been able to resolve any references for this publication.