Kinds Of Polymeric Materials Research Articles

Research Progress of Carbon-Silicone Composite Materials

Silicone is a kind of polymer material with high cross-linked structure, which is composed by Si-O-Si main chain. Due to the special molecular chain structure, silicone materials are characterized by oxidation resistance, aging resistance, high and low temperature resistance and chemical corrosion resistance. Moreover, silicone materials have processable properties, simple forming process, good mechanical property, non-toxic and pollution-free. Therefore, silicone has been widely concerned by researchers at home and abroad. In this paper, the main research progress and application directions of carbon-silicone composite at home and abroad in recent years are reviewed.

Influence of the aniline concentration on the morphology and property of polyaniline nanotubes and their polymerization mechanism

Polyaniline is a kind of polymer material with excellent electrochemical performance, and it stands out among a number of conductive polymer materials owing to its low cost, easy availability of raw materials, and excellent physical and chemical properties. However, the poor processability of polyaniline impedes its broad application. Preparing nanosized structure and introducing big molecular organic acids as dopant are practical strategies to solve this problem. Here using ammonium persulfate as oxidant, sodium dodecyl sulfate as surfactant, and 3,5-dinitrobenzoic acid as doping acid, polyaniline nanotubes were successfully prepared via emulsion polymerization method and characterized by various measurements. The influence of aniline concentration on the morphology and property of the product was explored. The polymerization mechanism of polyaniline nanotubes was discussed in detail based on the analysis of the microscopic morphology. As the concentration of aniline monomer increases, the position of the characteristic absorption peak in the infrared spectrum of the polyaniline main chain remains almost unchanged, but the ratio of benzene to quinone gradually increases. Along with the increasing aniline concentration, the crystallinity of polyaniline gradually decreases from 56.21% to 40.37%. In addition, the optimal conductivity is 2.05×10−2 S/cm when the concentration of aniline monomer is 0.5 mol/L.

Design and experiment of high load-bearing acrylic connection node for the world's largest acrylic spherical vessel

Acrylic is a kind of polymer material and is gradually applied to load-bearing components. The working stress and ultimate bearing capacity of the acrylic structure are the main design indexes. Aiming at the world’s largest acrylic spherical vessel, the structural design, finite element analysis and full-size prototype tensile test of a new acrylic connection node were carried out in this paper. This acrylic node will bear 90 kN tension force for 20 years. According to the viscoelastic characteristics of the material and the working environment, the stress of acrylic should be controlled below 3.5 MPa for long term used. At the time, the ultimate bearing capacity should be greater than 6 times the working load. According to the stress-strain curve of acrylic, its tensile strength is about 75 MPa. There is no obvious plastic deformation after fracture, showing the material characteristics of brittle fracture. According to the failure analysis of previous acrylic node structures and the characteristics of acrylic, the new acrylic node structure is proposed in this paper. Its performance is improved by reducing the cutting amount of acrylic nodes, optimizing the structure of embedded part and avoiding sharp corners. A 1/4 symmetrical acrylic node model is established FEA software, and the nonlinear problems such as material nonlinearity and friction contact are solved by finite element method. The FEA results show that the maximum principal stress of the node is about 2.92 MPa. The relative error between the FEA results and the experimental results is 7.24%, indicating that the FEA results are credible. The ultimate tensile load of the node can reach 1000 kN, which is about 11 times the working load. The failure of the node occurs at a sharp corner of the groove, instead of the maximum stress point. Therefore, stress concentration caused by sharp corners should be avoided in the design of acrylic structure.

물 흡수에 따른 다양한 고분자 재료의 기계적/트라이볼로지적 물성 연구

The physical, chemical and mechanical properties of polymer materials used in water environment for a long time will change due to their water absorption characteristics, which will affect their tribological properties. This work studied the changes of physicochemical, mechanical, and tribological properties for five kinds of polymer materials (polyethylene, polyformaldehyde,polyamide, polytetrafluoroethylene, and poly-ether-etherketone) before and after water absorption. The mechanism of water absorption for polymer materials was revealed by molecular dynamics simulation. The results show that the higher the water absorption of polymer, the larger the swelling volume, the more the surface hardness and compressive strength decrease, and the toughness and friction coefficient of the material increase obviously. The water absorption status of polymer materials is closely related to the polarity of molecular chain. Water molecules are easy to form hydrogen bonds with polymer molecular chains of high polarity, which is the main factor of water absorption.

Synthesis and Rheological Properties of Polyacrylamide Nanospheres and SiO2/PAM Composite Nanospheres

AbstractPolyacrylamide nanospheres are a kind of polymer material that can improve the development effect of oilfield water flooding and realize reservoir stimulation. However, due to its good water absorption, the strength cannot well meet the needs of practical production, and is forced to be limited to application on oil displacement. Therefore, in this paper, SiO2/PAM composite nanospheres were synthesized by the inverse microemulsion method to meet the needs of profile control and water shutoff in oilfields. The structure, oil displacement effect and rheological properties of polyacrylamide nanospheres and SiO2/PAM composite nanospheres were comparatively studied. The results show that both nanospheres are viscoelastic nanospheres. Since the elastic response is greater than the viscous response in SiO2/PAM composite nanospheres, and the polymer nanospheres do the opposite, there are significant differences in various rheological properties, such as variation of apparent viscosity with shear rate, creep recovery characteristics, viscoelasticity etc. This work provides a basis for the practical application of SiO2/PAM composite nanospheres in oilfields.

Application of Poly(ether sulfone)-Based Membranes in Clean Energy Technology.

Poly(ether sulfone) (PES) is a kind of polymer materials with excellent electrical insulation and acid/alkali stability. PES can be operated at high temperature continuously for a long time and still maintain excellent property stability in the environments with rapidly changed temperature, namely, great thermostability. Moreover, PES has low molding shrinkage, good dimensional stability and excellent film-forming characteristics. Compared with inorganic membranes, PES-based membranes have lower cost, which have received more attention and wide recognition in the field of clean energy technologies in recent years, such as flow batteries, fuel cells, water treatment, and gas separation. Therefore, this review summarizes the research status and prospect of the utilization of PES-based membranes in clean energy fields, in order to further promote their development and application.

Chemically Recyclable Poly(β-thioether ester)s Based on Rigid Spirocyclic Ketal Diols Derived from Citric Acid.

Incorporating rigid cyclic acetal and ketal units into polymer structures is an important strategy toward recyclable high-performance materials from renewable resources. In the present work, citric acid, a widely used platform chemical derived from biomass, has been efficiently converted into di- and tricyclic diketones. Ketalization with glycerol or trimethylolpropane afforded rigid spirodiols, which were obtained as complex mixtures of isomers. After a comprehensive NMR analysis, the spirodiols were converted into the respective di(meth)acrylates and utilized in thiol–ene polymerizations in combination with different dithiols. The resulting poly(β-thioether ester ketal)s were thermally stable up to 300 °C and showed glass-transition temperatures in a range of −7 to 40 °C, depending on monomer composition. The polymers were stable in aqueous acids and bases, but in a mixture of 1 M aqueous HCl and acetone, the ketal functional groups were cleanly hydrolyzed, opening the pathway for potential chemical recycling of these materials. We envision that these novel bioderived spirodiols have a great potential to become valuable and versatile bio-based building blocks for several different kinds of polymer materials.

Separation and quantitative detection of fermentation γ-polyglutamic acid

γ-Polyglutamic acid (γ-PGA) is a kind of polymer material with good biocompatibility and degradability, which is widely used in food, medicine, environmental protection, cosmetics and agriculture. As γ-PGA is produced by microbial fermentation, its separation, purification and quantitative detection are very important. In this study, the separation methods such as organic solvent precipitation, copper salt precipitation and membrane separation precipitation were mainly discussed, and the quantitative determination methods such as spectrophotometer, enzyme method and viscosity method of γ-PGA were discussed and compared. Furthermore, Molecular imprinting as a new method for the separation of γ-PGA has also been analyzed and discussed in order to provide a reference for the separation and purification of γ-PGA.

Application of Chitosan and Its Derivative Polymers in Clinical Medicine and Agriculture.

Chitosan is a biodegradable natural polymer derived from the exoskeleton of crustaceans. Because of its biocompatibility and non-biotoxicity, chitosan is widely used in the fields of medicine and agriculture. With the latest technology and technological progress, different active functional groups can be connected by modification, surface modification, or other configurations with various physical, chemical, and biological properties. These changes can significantly expand the application range and efficacy of chitosan polymers. This paper reviews the different uses of chitosan, such as catheter bridging to repair nerve broken ends, making wound auxiliaries, as tissue engineering repair materials for bone or cartilage, or as carriers for a variety of drugs to expand the volume or slow-release and even show potential in the fight against COVID-19. In addition, it is also discussed that chitosan in agriculture can improve the growth of crops and can be used as an antioxidant coating because its natural antibacterial properties are used alone or in conjunction with a variety of endophytic bacteria and metal ions. Generally speaking, chitosan is a kind of polymer material with excellent development prospects in medicine and agriculture.

The Effect of Phenyl Content on the Liquid Crystal-Based Organosilicone Elastomers with Mechanical Adaptability.

An elastomer with mechanical adaptability is a new kind of polymer material in which the increasing stress under continuous deformation is significantly inhibited in a large deformation area. Liquid crystal-based organosilicone elastomers, which can dissipate energy through reversible internal phase transition under external stimulation and have recoverable large deformation capacity, have drawn much interest as mechanical adaptability materials. However, there is no good way to control the mechanical adaptability at present. For this purpose, we prepared a new liquid crystal-based phenyl silicone rubber (LCMVPQ) using two-step click reactions and systematically explored the effect of phenyl content on its mechanical adaptability to achieve the regulation of mechanical adaptability. With an increase in phenyl content in the LCMVPQs, phenyl can hinder the rearrangement of the mesogenic units along the applied stress direction, which enables the adjustment of mechanical adaptability to meet the needs of different situations. In addition, the introduction of the liquid crystal phase impedes the internal friction of the molecular chain movement of the LCMVPQs and reduces the damping performance of silicone rubber. This research achieves the regulation of elastomers with mechanical adaptability and is expected to be applied in practical application fields.

Review on the Durability of Polypropylene Fibre‐Reinforced Concrete

Polypropylene fibre (PPF) is a kind of polymer material with light weight, high strength, and corrosion resistance. The crack resistance of concrete can be improved by adding PPFs. PPF can optimize the pore size distribution of concrete. As a result, the durability of concrete is significantly enhanced since PPF can block the penetration of water or harmful ions in concrete. This paper summarizes the influence of polypropylene fibre on the durability of concrete, including drying shrinkage, creep, water absorption, permeability resistance, chloride ion penetration resistance, sulfate corrosion resistance, freeze‐thaw cycle resistance, carbonation resistance, and fire resistance. The authors analysed the effects of fibre content, fibre diameter, and fibre hybrid ratio on these durability indexes. The durability property of concrete can be further improved by combining PPFs and steel fibres. The drawbacks of PPF in application in concrete are the imperfect dispersion in concrete and weak bonding with cement matrix. The methods to overcome these drawbacks are to use fibre modified with nanoactive powder or chemical treatment. At last, the authors give the future research prospects of concrete made with PPFs.

Machinability of the Thermoplastic Polymers: PEEK, PI, and PMMA.

The thermoplastic polymer such as poly(methyl methacrylate) (PMMA), polyetheretherketone (PEEK), and polyimide (PI) is a kind of polymer material with properties of good mechanical strength. It has been widely used in the fields of aerospace, optical engineering, and microfluidics, etc. Thermoplastic polymers are considered to be one of the most promising engineering plastics in the future. Therefore, it is necessary to further study its mechanical properties and machinability, especially in ultra-precision machining. Furthermore, mechanical property and machinability were studied in this work. Through the dynamic mechanical analysis experiment, the elastic modulus and temperature effect of PMMA, PEEK, and PI are analyzed. In addition, the high-speed micromilling experiment is conducted to show that the surface roughness, burrs, and cutting chip characteristics in the high-speed micromilling process. In general, the surface quality of the brittle removal is generally better than that of the viscoelasticity state. The results show that PMMA, PEEK, and PI have good mechanical properties and machinability. Base on the results, the material will be in a viscoelastic state as the temperature increases. The surface quality of the brittle removal is generally better than the viscoelastic state.

Tribological and Vibration Properties of Three Different Polymer Materials for Water-Lubricated Bearings.

Water-lubricated bearings usually operate under severe environmental conditions, most likely in the mixed regime, in which surface contact between the drive shaft and the bearing sleeve is often significant. This presents great challenges to bearing design, especially material selection. The Tenmat, Thordon, and Rubber are common water-lubricated bearing composites. In this paper, by using a block-on-ring test apparatus, the Stribeck curve, wear rate, and vibration characteristics of three kinds of polymer materials in water-lubricated bearings (Tenmat, Thordon SXL, and Ben Teng Group (BTG) Rubber) under low speed and heavy load were studied. The experimental results show that, under the same working conditions, BTG rubber has excellent tribological properties and vibration properties. The research method in this paper can provide references for the selection of materials used for friction pair, improvement of working performance and vibration reduction of water-lubricated bearings in the future.

Conductive Hydrogels-A Novel Material: Recent Advances and Future Perspectives.

A conductive hydrogel is a kind of polymer material having substantial potential applications with various properties, including high toughness, self-recoverability, electrical conductivity, transparency, freezing resistance, stimuli responsiveness, stretchability, self-healing, and strain sensitivity. Herein, according to the current research status of conductive hydrogels, properties of conductive hydrogels, preparation methods of different conductive hydrogels, and their application in different fields, such as sensor and actuator fabrication, biomedicine, and soft electronics, are introduced. Furthermore, the development direction and application prospects of conductive hydrogels are proposed.

Polymer Materials for High-Performance Triboelectric Nanogenerators.

As an emerging branch of energy conversion technologies, the triboelectric nanogenerator (TENG) pioneers a brand‐new path to effectively harness varieties of mechanical energies for the purpose of powering and/or sensing. Since its invention in 2012, the TENG has experienced a booming and revolutionary development in every respect, ranging from materials synthesis and modification, architecture design to performance optimization, power management, and application exploration. In comparison to the organic solar cell and organic light‐emitting diodes, TENG is a unique technique that opens the venue of using polymer materials (PMs) for harvesting mechanical energy. So far, by virtue of superior charge transfer and capturing capabilities during friction, various kinds of PMs have been developed and used as triboelectric materials in order to achieve high‐performance TENGs. Here, this work focuses on the utilization and development of PMs for the TENGs technology and first gives a summary of main PMs that are frequently adopted in currently reported energy‐harvesting TENGs. Second, several kinds of PMs used lately in a few novel TENGs for special or specific energy‐harvesting circumstances are introduced and highlighted. Finally, the perspectives on and challenges in developing high‐performance PMs toward TENGs technology are conceived and expected to be instructive to future research.

Relationship between the Ionization Degree and the Inter-Polymeric Aggregation of the Poly(maleic acid-alt-octadecene) Salts Regarding Time.

Alternating amphiphilic copolymers are macromolecular systems with a polarity duality in their structure, since they are generally formed by alternating segments corresponding to a potential electrolyte group and an alkyl (aliphatic or aromatic) group. These systems, depending on the ionization degree, as well as the time, may form different types of intra and interpolymeric aggregates in aqueous media. Therefore, this study, which in fact is the continuation of a previously reported work, is focused on establishing how the ionization degree of the sodium and potassium salts of the poly(maleic acid-alt-octadecene) affect zeta potential, pH, electrical conductivity, particle size, polydispersity index, and surface tension over time. The results showed that polymeric salts with a high ionization degree in aqueous media formed homogeneous systems with bimodal sizes and high zeta potential values, which tended to quickly become less negative, lowering the pH and slightly increasing the electrical conductivity; while systems with low ionization degree lead to the opposite, forming heterodispersed systems with several populations of particle sizes, high polydispersity, low zeta potential values, neutral and invariable pH values, and high electrical conductivity values. Consequently, these results suggest that the values of particle size, polydispersity index, zeta potential, pH, and electrical conductivity change regarding the polymeric ionization degree, as well as the time. Therefore, such variables should be considered and controlled when working with this kind of polymeric materials.

Molecular modelling of the effect of loading rate on elastic properties of CNT-polyethylene nanocomposite and its interface

Polymer composites reinforced by carbon nanotubes (CNTs) are so attractive for many mechanical applications due to their higher strength and elastic modulus than those of polymer itself. Besides the mechanical performance of CNTs being superior, another main reason is related to the CNT-polymer interface. The interface at nanoscale level plays a key role of load transfer. These kind of polymeric materials are highly sensitive to temperature and loading rates (or strain rates), and further as the matrix with nanoparticle additives, the mechanical properties of the composite have also been found to be strongly dependent on temperature and loading rates. In this paper, specifically for the CNT-reinforced polyethylene nanocomposite, we studied the effect of loading rates on the elastic properties of the nanocomposite and its CNT-polyethylene interface by molecular dynamics (MD) modelling. Our simulated results are well agreed with the ones that are calculated on the rule-of-mixtures (ROM) and from other publications. The results show that higher loading rates lead to larger stress and Young’s modulus of the nanocomposite. And on the atomistic model with taking account of the CNT-polyethylene interface, we found that the interface thickness is independent on loading rates, while its interaction energy and Young’s modulus are related to selected CNTs, and dependent on loading rates. Both of them reach the largest value when the CNTs with the highest aspect ratios (correspondingly the highest specific surface areas) are selected and the nanocomposite being under the fastest loading rate. These results are very valuable for deeply understanding the elastic properties of CNT-polyethylene nanocomposites and their microstructural design.

Nano-emulgel: Emerging as a Smarter Topical Lipidic Emulsion-based Nanocarrier for Skin Healthcare Applications.

In recent decades, enormous efforts for different drug discovery processes have led to a number of drug molecules available today to overcome different challenges of the health care system. Unfortunately, more than half of these drugs are listed in either BCS (biopharmaceutical classification system) class II/ IV or both are eliminated from the development pipeline due to their limited clinical use. A nanotechnological approach bears much hope and lipoidal fabrication is found to be suitable for the delivery of such drugs. Nanoemulsion based gel i.e. nanoemulgel out of different nanolipoidal formulations has been found to be a suitable approach to successful drug delivery through topical routes. In past few years many herbal and synthetic active pharmaceutical ingredients (APIs) has been patented as nano sized emulsified gel for various therapeutic activities. Nanoemulgel is basically an emulsion-based topical gel formulation, where nanosized emulsion globules can be prepared with the help of high energy or low energy methods and further converted into nanoemulgel by adding a suitable gelling agent. Nanoemulgel fabrication enlists various kinds of polymeric materials, surfactants and fatty substances of natural, synthetic and semi-synthetic nature with a globule size range from 5 to 500 nm. Nanoemulgel can be applicable to various acute and chronic diseases through topical routes. Nanoemulgel preparations of many recently approved drugs are being used successfully in different areas of health care and have re-defined the significance of topical route of delivery as compared to other routes. However, along with various improvements in the current state of the delivery system, the safety factor needs to be taken into account by toxicological studies of the materials used in such formulations.

New Kind of Polymer Materials Based on Selected Complexing Star-Shaped Polyethers.

In today’s analytical trends, there is an ever-increasing importance of polymeric materials for low molecular weight compounds including amines and drugs because they can act as carriers or capture amines or drugs. The use of this type of materials will allow the development of modern materials for the chromatographic column beds and the substrates of selective sensors. Moreover, these kinds of materials could be used as a drug carrier. Therefore, the aim of this study is presenting the synthesis and complexing properties of star-shaped oxiranes as a new sensor for the selective complexation of low molecular weight compounds. Propylene oxide and selected oxirane monomers with carbazolyl in the substituent were selected as the monomers in this case and tetrahydrofuran as its solvent. The obtained polymer structures were characterized using the MALDI-TOF. It was found that in the initiation step potassium hydride deprotonates the monomer molecule and takes also part in the nucleophilic substitution. The resulting polymeric material preferably cross-linked with selected di-oxiranes (1,2,7,8-diepoksyoktan in respect ratio 3:1 according to active center) was then used as a stationary phase in the column and thin layer chromatography for amine separation and identification. Sorption ability of the resulting deposits was determined using a quartz microbalance (QCMB). The study was carried out in stationary mode and flow cells to simulate actual operating phase conditions. Based on changes in electrode vibration frequency, the maximum amount of adsorbed analyte and the best conditions for its sorption were determined.

Effects of Typical Physical Properties on Tribological Behaviors of Three Kinds of Polymer Materials for Water-Lubricated Bearings

The stretching, shearing, deformation, peeling, and temperature rise phenomena at the micro–nano contact interface have a great influence on its tribological properties and significantly affect the service life of key moving parts made of polymers. The physical properties of the three typical polymer materials used for ship bearing polymer materials (ultra-high-molecular-weight polyethylene, synthetic rubber, and polypropylene) were examined to investigate their effects on the wear behaviors. The results showed that synthetic rubber has good wear resistance because of its excellent shear strength, tensile strength, and high initial thermoplastic deformation temperature. Low initial thermoplastic deformation temperature resulted in great wear to the polypropylene material under dry friction, whereas its good wettability resulted in good wear resistance under water-lubricated condition. The ultra-high-molecular-weight polyethylene had the poorest wear resistance under water-lubricated condition because it had the poorest shear strength and tensile strength. The knowledge gained herein provides a better understanding of the relationships between the physical behaviors of polymer materials and their friction and wear mechanisms, along with guidance for selecting and designing polymer friction pairs for ship bearings.