Properties Of Polymeric Materials Research Articles

Regulation of Dihedral Angle on Molecular Engineering for Enhancing Triboelectric Performance

AbstractThe performance of triboelectric polymers relies on their molecular structure. Therefore, investigating how to construct high‐performance molecular structures of triboelectric polymers becomes imperative, yet the relationship between microscopic structural parameters and triboelectric performance remains unclear. In this study, the relationship is studied between dihedral angles of adjacent conjugated planes and triboelectric performance. Various polyimide monomers are synthesized to manipulate the conjugated dihedral angles within the molecular chains. Introducing larger dihedral angles in polyimides (PIs) reduces the conjugation between molecular chains, suppressing the formation of charge transfer complexes (CTCs), and widening the energy gap between molecular orbitals. With the increase in dihedral angles, the output performance improved by 100%. The surface charge density of 335 µC·m−2 is achieved through the synergistic effect of the high charge retention capability of the PI film and the high triboelectric properties of the corona‐polarized fluorinated ethylene propylene (FEP). A large dihedral angle can form numerous deep traps and effectively prevent charge escaping while ensuring stable output. This study provides a feasible strategy for investigating the construction of high triboelectric performance molecular structures, enriching the understanding of how molecular structures influence the triboelectric properties of polymer materials and promote high‐performance fluorine‐free and environmentally friendly polymers.

Modeling and solution of eigenvalue problems of laminated cylindrical shells consisting of nanocomposite plies in thermal environments

This work is dedicated to the modeling and solution of eigenvalue problems within shear deformation theory (SDT) of laminated cylindrical shells containing nanocomposite plies subjected to axial compressive load in thermal environments. In this study, the shear deformation theory for homogeneous laminated shells is extended to laminated shells consisting of functionally graded (FG) nanocomposite layers. The nanocomposite plies of laminated cylindrical shells (LCSs) are arranged in a piecewise FG distribution along the thickness direction. Temperature-dependent material properties of FG-nanocomposite plies are estimated through a micromechanical model, and CNT efficiency parameters are calibrated based on polymer material properties obtained from molecular dynamics simulations. After mathematical modeling, second-order time-dependent and fourth-order coordinate-dependent partial differential equations are derived within SDT, and a closed-form solution for the dimensionless frequency parameter and critical axial load is obtained for first time. After the accuracy of the applied methodology is confirmed by numerical comparisons, the unique influences of ply models, the number and sequence of plies and the temperature on the critical axial load and vibration frequency parameter within SDT and Kirchhoff–Love theory (KLT) are presented with numerical examples.

Obtaining unsaturated polyester resins using products of recycled polyethylene terephthalate solvolysis

A technique for obtaining an unsaturated polyester resin based on recycled polyethylene terephthalate has been developed. The process of curing an unsaturated polyester resin under the action of styrene, a peroxide compound (Butanox 50M) and an accelerator (cobalt ortoate) has been studied. The physical and mechanical properties of polymeric materials based on the developed resin have been studied, it was found that their strength depends on the mass fraction of recycled polyethylene terephthalate in the oligoether polyol used in the synthesis.

Graphene nanoribbon hydrogel scaffold for highly conductive and robust polyimide nanocomposite

Graphene nanoribbon hydrogel scaffold for highly conductive and robust polyimide nanocomposite

Dynamic mechanical behavior of CNT-reinforced epoxy under medium-strain rate: A comparative study

Dynamic mechanical behavior of CNT-reinforced epoxy under medium-strain rate: A comparative study

Study the optical properties of polymer material and its applications

Study the optical properties of polymer material and its applications

Study the mechanical properties of polymer material and its applications

Study the mechanical properties of polymer material and its applications

An Innovative Approach to Assessing the Quality of Organoleptic Properties of Base Polymers in Orthopedic Dentistry

Modern technologies using an «electronic nose» imitating the human sense of smell open up new prospects for the objective assessment of the organoleptic properties of polymer materials. The purpose of the study was to compare the level of emissions of volatile organic compounds from modern base materials used in various technological processes for the manufacture of removable denture structures, as well as to assess the possible organoleptic properties of the finished dentures in comparison with known analogues using an «electronic nose» gas analyzer. For this purpose, samples were made from different polymer base materials in the amount of 26 pieces, which were studied using an “electronic nose” gas analyzer using the author’s method [Kuchmenko et al., 2023]. The study confirmed the effectiveness of the proposed improved technology in reducing the noise level of volatile organic compounds in samples made from the «Belakril-E GO» base material by 29 % compared to similar samples produced using standard technology. A reduction in the amount of volatile organic compounds that can cause unwanted odors confirms the higher purity and quality of the polymer and will contribute to a more comfortable adaptation of patients to removable dentures made from this polymer.

Revealing the ESIPT process in benzoxazole fluorophores within polymeric matrices through theory and experiment.

The impact of the polymeric matrix on the photophysical characteristics of monomeric dyes responsive to excited-state intramolecular proton transfer (ESIPT) was investigated through UV-Vis absorption as well as steady-state and time-resolved emission spectroscopies. For this purpose, two benzoxazole monomers (M1 and M2) with acryloyl groups at different positions in their molecular structures were employed to facilitate covalent bonding within a styrene chain. Our findings reveal significant variations in their excited-state properties due to the proximity of the acryloyl groups, which affects the energy barrier of the ESIPT reaction, the emission wavelength, and the balance between the normal and tautomeric forms. The experimental results were corroborated through theoretical investigations at the DFT/TDDFT level, specifically using the B3LYP-D3/def2-TZVP methodology. Three notable observations emerged: donor/acceptor groups at the meta/para positions induced electron distribution changes, causing red-shifted emission for M2; in the polymer film, particularly in PM1, intramolecular hydrogen bond deactivation favored N* emission over T* emission; and the zwitterionic character of the T* species. This study underscores the advantages of functionalization in polymers, which can lead to colorless films and prevalent N* or T* emission, and contributes valuable insights into molecular design strategies for tailoring the photophysical properties of polymeric materials.

Structural, topological, and rheological characteristics of entangled short-chain branched polymer melts under shear flow in comparison with the linear analog

We present a detailed analysis of the general influence of short branches on the structural, topological, and rheological behaviors of entangled short-chain branched (SCB) polyethylene (PE) melt systems under shear flow via direct comparison with the corresponding linear analogs using extensive atomistic nonequilibrium molecular dynamics (NEMD) simulations, for a wide range of flow strengths. In comparison with the linear melt, the SCB systems generally exhibit more compact chain structures and larger dynamic resistance, in response to an imposed flow field at all flow strengths. These features essentially arise from (i) the increased chain stiffness due to the torsional restriction of backbone atoms around the branch points and (ii) the fast random Brownian motion of short branches via their very short characteristic relaxation time. We analyzed various structural and rheological properties, such as anisotropic chain dimension and orientation and their detailed distributions, topological characteristics of the entanglement network, material functions, chain rotation dynamics, and flow birefringence. Distinctive physical characteristics of the entangled SCB systems exposed by these individual properties can be consistently understood based on the fundamental structural and dynamical roles of short branches. These findings are considered informative in our systematic understanding and prediction for the general rheological behaviors of long entangled SCB polymer systems under flow, and in tuning the material properties of SCB polymers in practical applications.

Comparison of the heat resistance of flame retardants of various classes for polymer cable channels

The article presents a comparison of different classes of flame retardants, the mechanisms of their action and their effect on the physico-chemical properties of polymer materials. Based on studies of the heat resistance of flame retardants, an optimal formulation for the manufacture of polymer cable channels has been proposed.

Ultrathin Al2O3 film modification on waterborne epoxy coatings by atomic layer deposition for augmenting the corrosion resistance

The polar channels formed by the curing of waterborne anticorrosive coatings compromise their water resistance, leading to coating degradation and metal corrosion. To enhance the anticorrosive performance of waterborne coatings, this study proposed a novel method of depositing ultrathin Al2O3 films on the surface of waterborne epoxy coatings by atomic layer deposition, a technique that can modify the surface properties of polymer materials by depositing functional films. The Al2O3-modified coatings exhibited improved sealing and barrier properties by closing the polar channels and surface defects and cracks. The surface structure and morphology of the modified coatings were characterized by x-ray photoelectron spectroscopy and scanning electron microscopy. The hydrophilicity and corrosion resistance of the modified coatings were evaluated by water contact angle measurement, Tafel polarization curve, and electrochemical impedance spectroscopy. The results indicated that the water contact angle of the Al2O3-modified coating increased by 48° compared to the unmodified coating, and the protection efficiency of the modified coating reached 99.81%. The Al2O3-modified coating demonstrated high anticorrosive efficiency and potential applications for metal anticorrosion in harsh marine environments.

Effect of Block Copolymer Self-Assembly on Phase Separation in Photopolymerizable Epoxy Blends.

Directing self-assembly of photopolymerizable systems is advantageous for controlling polymer nanostructure and material properties, but developing techniques for inducing ordered structure remains challenging. In this work, well-defined diblock or random copolymers were incorporated into cationic photopolymerizable epoxy systems to investigate the impact of copolymer architecture on self-assembly and phase separated nanostructures. Copolymers consisting of poly(hydroxyethyl acrylate)-x-(butyl acrylate) were prepared using photoiniferter polymerization to control functional group placement and molecular weight/polydispersity. Prepolymer configuration and concentration induced distinctly different effects on the resin flow and photopolymerization kinetics. The diblock copolymer self-assembled into nanostructured phases within the resin matrix, whereas the random copolymer formed an isotropic mixture. Rapid photopolymerization and ambient temperature conditions during cure facilitated retention of the self-assembled phases, leading to considerably different composite morphology and thermomechanical behavior. Increased loading of the diblock copolymer induced long-range ordered cocontinuous structures. Even with nearly identical prepolymer composition, controlled nanophase separation resulted in significantly enhanced tensile properties relative to those of the isotropic system. This work demonstrates that controlling phase separation with a block copolymer architecture allows access to nanostructured photopolymers with unique and enhanced properties.

Nanocomposites with polyurethane polymer matrix/ particulate material

The environment is currently considered one of the main concerns of the industrial sector and society. In the particular case of the oil industry, one of the biggest environmental catastrophes that can happen are large oil spills, where to reduce or minimize the environmental damage caused, various cleaning methods are used. Thus, nanocomposites aim to change the mechanical, physical and chemical properties of polymer matrices. The main focus of modifying Polyurethanes has been directed to materials science, the objective of which is to obtain particulate materials, allowing surfaces to be differentiated, reducing surface energy and increasing interlayer spacing for polymer intercalation. This particulate material, produced and modified, interspersed with the Polymer, allows us to absorb crude oil, as it is hydrophobic and, consequently, organophilic. The factors that define the degree of sorption of organic compounds are: hydrophobicity, porosity, molecular structure and volume, and the volume of the surface area of the sorbent material. Therefore, the sorbent must be wettable by the hydrophobic compound and non-wettable or slightly wettable by water. Sorbent materials must have characteristics such as a large surface area, high porosity, good oleophilic character, as well as good oil retention capacity and ease of application. Polyurethane presents several of these characteristics, making it an interesting sorbent for the oil sector. The present work studies the obtaining of these nanocomposites, using a particulate material to combat leaks or spills of hydrocarbons.

Exploiting Waste towards More Sustainable Flame-Retardant Solutions for Polymers: A Review.

The development of sustainable flame retardants is gaining momentum due to their enhanced safety attributes and environmental compatibility. One effective strategy is to use waste materials as a primary source of chemical components, which can help mitigate environmental issues associated with traditional flame retardants. This paper reviews recent research in flame retardancy for waste flame retardants, categorizing them based on waste types like industrial, food, and plant waste. The paper focuses on recent advancements in this area, focusing on their impact on the thermal stability, flame retardancy, smoke suppression, and mechanical properties of polymeric materials. The study also provides a summary of functionalization methodologies used and key factors involved in modifying polymer systems. Finally, their major challenges and prospects for the future are identified.

Identification method on the vibration properties of a periodic core sandwich: Thermal impact on the band gap

This paper focuses on the thermal impact of filtering properties on sandwich structures with periodic core. The evolution of the bandgap is carefully studied as a function of temperature. Sandwich structure allows to shear the viscoelastic core layer and increases passive damping. Two polymers are selected for their viscoelastic properties and their adhesion properties with metal surfaces. The mechanical properties, shear modulus G(ω) and loss factor η(ω) of these polymers, are determined at temperature by an inverse method. The periodicity of the sandwich structure is achieved by alternating two materials with specific viscoelastic properties in the core, allowing resonant frequencies to be located in beams creating frequency ranges without resonant peaks. Temperature has a strong influence on the mechanical properties of polymer materials. This is why we felt it was important to be able to carry out a temperature investigation. Numerical finite element modelling is developed considering periodicity and temperature. Periodic sandwich fabricated in our laboratory are tested under thermal conditioned. The results show the importance of considering the effect of temperature. It has a direct impact on the filtering properties obtained by periodic structures.

Preparation and properties of a metal-organic frameworks polymer material based on Sa-son seed gum capable of simultaneously absorbing liquid water and water vapor

Atmospheric water harvesting (AWH) technology has attracted significant attention as an effective strategy to tackle the global shortage of freshwater resources. Work has focused on the use of hydrogel-based composite adsorbents in water harvesting and water conservation. The approaches adopted to make use of hygroscopic inorganic salts which subject to a "salting out" effect. In this study, we report the first use of modified UIO-66-NH2 as a functional steric cross-linker and Sa-son seed gum was used as polymeric substrate to construct super hygroscopic hydrogels by free radical copolymerization. The maximum water uptake on SMAGs (572cm3·g-1) outperforms pure UIO-66-NH2 (317cm3·g-1). Simultaneously, our first attempt to use it for anti-evaporation applications in an arid environment (Lanzhou, China) simulating sandy areas. The evaporation rate of the anti-evaporation material treated with 0.20% super moisture-absorbent gels (SMAGs) decreased by 6.1% over 64h period under natural condition in Lanzhou, China. The prepared material can not only absorb liquid water but also water vapor, which can provide a new way for water collection and conservation technology. The design strategy of this material has wide applications ranging from atmospheric water harvesting materials to anti-evaporation technology.

Multi-objective design optimization of polymer spur gears using a hybrid approach

Polymer gears are used in applications requiring small to moderate loads to effectively transmit power and use the limited place available as possible. Various commercial standards have been provided designers with the rating criteria and acquaintance of different polymer material properties for the process of design. However, the result was unsatisfactory in terms of economy, time, and the optimality of the product. Thus, classic and stochastic algorithms have been embraced to reach the best design of polymer gears. Taking advantage of the former and latter algorithm’ methods, optimal design of gears could be attained with an increased gear life span and decreased failure modes. In this study, polyoxymethylene (POM) spur gear set has been optimized combining the mathematical model from plastic standards and hybrid optimization approach of multi-objective genetic algorithm (MOGA) and sequential quadratic programming (SQP). Weight and power loss were the objective functions. Five design variables were optimized with the satisfaction of bending and contact stresses, temperature, wear, and deformation as constraints. Solutions of the problem were formulated as Pareto optimal set. The results of multi-objective were compared with previously published single-objective optimization. The results favored multi-objective optimization (82.67%, 31.39% reduction in weight and power loss respectively) as it gave the best applicable solution fitting in real life situations. The results also went hand in hand with literature confirming the efficiency of the proposed algorithm. With the variation of operating parameters, various optimal designs could be obtained where the designers can choose the design that is suitable for a particular application.

Influences of sodium hydroxide and oxalic acid treatments on physical, mechanical, thermal properties, and morphology of ramie fibers

Influences of sodium hydroxide and oxalic acid treatments on physical, mechanical, thermal properties, and morphology of ramie fibers

Development of Low-Molecular-Weight Gelator/Polymer Composite Materials Utilizing the Gelation and Swelling Process of Polymeric Materials.

The creation of polymer composite materials by compositing fillers into polymer materials is an effective method of improving the properties of polymer materials, and the development of new fillers and their novel composite methods is expected to lead to the creation of new polymer composite materials. In this study, we develop a new filler material made of low-molecular-weight gelators by applying a gelation process that simultaneously performs the swelling (gelation) of crosslinked polymer materials and the self-assembly of low-molecular-weight gelators into low-dimensional crystals in organic solvents within polymer materials. The gelation process of crosslinking rubber-based polymers using alkylhydrazides/toluene as the low-molecular-weight gelator allowed us to composite self-assembled sheet-like crystals of alkylhydrazides as fillers in polymeric materials, as suggested by various microscopic observations, including infrared absorption measurements, small-angle X-ray diffraction measurements and thermal analysis, microscopy, and infrared absorption measurements. Furthermore, tensile tests of the composite materials demonstrated that the presence of fillers improved both the Young's modulus and the tensile strength, as well as the elongation at yield. Additionally, heat treatment was shown to facilitate filler dispersion and enhance the mechanical properties. The findings demonstrate the potential of self-assembled sheet-like crystals of low-molecular-weight gelators as novel filler materials for polymers. The study's composite method utilizing gelators via gelation proved effective.