Papers by Keyword: Polymer

Abstract: This paper deals with the problematics of polymer repair and adhesive mortars. In this study, the vinyl ester and epoxy resins filled with siliceous filler are used. This paper studies physical-mechanical properties and chemical resistance of developed mortars. The compressive strength, flexural strength and visual evaluation of reaction and degradation of polymer mortars in presence of common acids, alkalis and other compounds are compared. The results show, the amine-based epoxy mortar can withstand against a large variety of solutions, but the overall chemical resistance of vinyl ester mortar is higher.

Abstract: Reduced glutathione (GSH) is incorporated in polymeric wound dressings to prevent oxidative stress-induced cellular damage and the development of chronic wounds. The present study investigates the influence of polyvinyl alcohol (PVA), polyethylene oxide (PEO), and PVA/PEO blend polymeric solutions on the stability of GSH during the preparations or storage. The stability was studied in three concentrations which were 3%, 5% and 8%, after sometimes between 0 to 7 days. The level of GSH achieved the highest electron donor activity at day 7 in 8% PVA/PEO (95.42%) and 8% PVA (94.27%) solutions, whereas GSH activity decreased when incorporated with PEO solutions. Such a decrease in the GSH activity due to PEO being less water-resistant and hydrolytic degradation susceptibility could expose the GSH to an aqueous environment and lead to the loss of GSH activity. In conclusion, a higher concentration of polymer and less-water resistant polymers can shield the GSH from an aqueous environment and maintain its stability in the polymer solutions used in wound dressing applications.

Abstract: Large scale buoyant structures typical of offshore wave energy generation devices may be produced using the rotational foam moulding process. Due to the challenging environmental conditions these parts experience during their lifetime at sea, it is important that the structures are optimised to ensure acceptable mechanical performance. Foams containing large cells suffer a reduction in mechanical properties; therefore, an optimal foam contains small, evenly sized, and well distributed bubbles in large numbers. Due to the lower pressures used in the process, this can be challenging to achieve. Careful selection of material and processing conditions is required to achieve an optimal structure. A unique bench-based rig was used to observe developing foam structures. A camera was used to record the foam height change at intervals. Foam height change was obtained using digital image analysis. Several parameters were studied such as the polymer particle size or the mould pressure for example. In addition to the foam height change, foam density were analysed. It is found that mould pressure, polymer particle size, chemical blowing agent concentration, and polymer rheology may be used to control the foamed structures.

Abstract: A material testing apparatus for measuring the biaxial deformation behavior of a polymer tube has been developed to quantitatively evaluate the deformation behavior of polymeric materials. The testing apparatus can apply axial force and internal pressure to a tubular specimen. A noncontact strain measurement system was also developed, and the biaxial strain components and the radius of curvature in the axial direction of the bulging specimen are continuously measured to control the stress path applied to the specimen. Polyethylene tube with an outer diameter of 17 mm and a thickness of 2 mm are used as a test sample. The tubular specimens were subjected to linear stress paths with stress ratios of σ_Φ:σ_θ =1:0, 4:1, 2:1, 4:3, 1:1, 3:4, 1:2, 1:4, and 0:1, where σ_Φ and σ_θ are the axial and circumferential stress components, respectively, applied to the central area of the bulging specimen. Loading and unloading tests were performed to determine the biaxial true stress-logarithmic plastic strain curves. The strain rate was 1×10^-3s^-1. From these test results, contours of plastic work and the directions of the plastic strain rates were measured to identify a proper material model for the test sample using the Yld2000-2d yield function (Barlat et al., 2003).

Abstract: Membrane technology advancement has gained momentous consideration around the globe because of their appealing highlights, such as effectiveness, low expenses, and effective solutions for longstanding issues in alchemical industries. This study expected to incorporate graphene nanoparticles into Polyvinylidene difluoride (PVDF) to form nanofiltration (NF) layers using DMF (Dimethyl formamide) as solvent via DIPS (diffusion induced phase separation) technique. PVDF polymer membrane performances with varied percent (1 – 6% wt.) of graphene concentrations are studied Infrared spectral, water uptake, water contact angle, and ion rejection measurements. Scanning electron microscope (SEM) analysis showed that the pore size is often regulated by incorporating graphene nanoparticles (80-90 nm) as compared to PVDF membranes. The PVDF membranes exhibited a relative increase in the contact angle from PVDF to PVDF-G6% i.e. 50.3° to 63.46 ± .3, thus, showing a relative increase in hydrophobicity. The higher percent of graphene (> 6% by wt.) results in nanoparticle accumulation that showed the performances of PVDF/graphene rejection possessing relatively the same results. The results confirmed that the prepared membranes possess an excellent ability to treat wastewater.

Abstract: The article examines the aspects of predicting the durability of equipment components assembled using polymer reinforcing compounds. A method for calculating the key parameters of joints that have a primary impact on the durability of friction units is presented.

Abstract: The paper discusses computer modeling of the temperature dependences of the dielectric constant of polymer composite materials. Issues of the combined radio wave and thermal methods of diagnostics of nondestructive inspection of the polymer composite materials in the laboratory conditions are considered. The paper offers a method for combining the measurement and heating processes. This method can be implemented, the way is to do the heating and the measurement at the same frequency with using a high-power sounding wave. As a result, the radiant material heating is obtained, and we judge about the substance parameters and a presence of defects in the substance by a reflected wave in an indirect method. A descriptive characteristic of such a problem boils down to describing all the processes in the sample by the electrodynamic theory. The heating process can also be described by the electrodynamics equations, but the process will be described by the thermal equations in the nonstationary heating conditions in the most accurate way.

Abstract: Recently, perovskite nanocomposites have attracted much ‎attention as active layers due to the relatively high stable efficiency of solar cells based on them. In this ‎paper, we study perovskite nanocomposite layers based on ‎semiconductive/nonconductive molecules or polymers, their deposition methods, properties, and ‎influence on the device performance. We have found that the quality of the ‎perovskite layer (morphology and crystallinity, cross-linked grains, trap states density, as well as ‎conductivity and charge carrier mobility) is strongly affected by various factors ‎related to the additive: such as type (i. e. semiconductive or nonconductive, ‎molecule or polymer), chemical structure (backbone length and ‎molecular weight, functional groups, π system, side chains, donating atoms and basicity), amount,‎ solubility, conductivity, photoactivity, polarity, hydrophobicity, and addition methods. Due to the small amounts added, these additives can lead to slight changes in energy levels, bandgap (E_g), and light absorption ‎properties. Ultimately, using the suitable deposition method and additive at an optimal amount can ‎greatly improve the stability and efficiency of the devices and reduce ‎hysteresis.

Abstract: During a world-wide pandemic solutions for the production of anti-viral products is an at all-time high, motivating research into a wide array of potential solutions, with special interest to those capable of being deployed with as close to zero alterations to the production methods. The present work investigates the potential of using two additives, a commercially available masterbatch and a copper oxide powder, compounded using LDPE as a matrix, to be incorporated in a standard industrial setting. The final products were conventional polyester-based TNTs with 5 g m^-2 coatings obtained from the micronized LDPE compounds. Antimicrobial and antiviral properties were evaluated for the two TNT products, revealing both solutions as technical equivalents and capable solutions for the production of PPEs.

Abstract: The influence of fiber length and treated chemically on wear properties by using jute fibers reinforcing in polymer-matrix composites (PMC) has been considered. From the results, it was found that The wear rate decreasing with increasing load from (78.6 -70.35)%, (65.6-59.16)% and (72.9-67.7)% for (5,10,15) KN load respectively that decreasing due to disintegrating the sample's surface under increasing loads. also, The wear rate decreases with increasing load from (78.6 -70.35) gm/mm (65.6-59.16)gm/mm and (72.9-67.7) gm/mm for (5,10,15) KN load respectively that decreasing due to disintegrating the sample's surface under increasing loads. also,The rate of wear decreases with an increase in the length of the fibers by (65%), due to the effect of fiber length that causes difficulty in separating between fibers from the polymeric material, which means that the material is resistant to collapse and also in the presence of a chemical in the processing, which causes a strong bond and good adhesion between the reinforcing material and the material The basis resulting from pitting caused by chemical treatment.