High-performance Engineering Thermoplastics Research Articles

High-performance thermoplastic nanocomposites for aerospace applications: A review of synthesis, production, and analysis

Thermoset polymers are cured under natural or synthetic created conditions and retain their solid form when exposed to heat. Unlike thermosets, thermoplastics melt when exposed to heat after production. Thermoplastics are preferred as raw materials because they can be easily shaped after production, have a high shelf life and are recyclable. In this regard, the prominence of high-performance engineering polymers in recent years has led to the preference of alternative polymers to thermosets. High-performance engineering thermoplastics include thermoplastics such as polyphenylene-sulfide (PPS), polyether-ether-ketone (PEEK), polyether-ketone-ketone (PEKK), polyphenylene-ether, polysulfone,polyoxadiazole, polyimide, polyether-amide, polyether-amide-imide, polynaphthalene, and polyamide-imide. These polymers exhibit application potential in aerospace, defense, automotive, marine, energy, and medical sectors. In challenging conditions such as high pressure, temperature, and corrosive environments, they possess high service temperatures, enhanced mechanical and physical properties, preferable chemical resistance as well as out-of-autoclave and rapid processing properties. In this review article, nanomaterial production methods (bottom-up and top-bottom) are mentioned. In the following sections, PPS, PEEK, and PEKK thermoplastics are explained, and carbon- and boron-based nano additives used in constructing nanocomposites are investigated. In the last section, PPS, PEKK, and PEEK polymer nanocomposites are investigated.

Synthesis and characterization of long carbon chain polyamide 1012 modified polyamide 6 via melt copolymerization

Polyamide6 is a vital high-performance commercial engineering thermoplastics polymer, but it exhibits low toughness and high hydrophilicity. To improve its disadvantages, the facile melt co-polycondensation method was proposed to synthesis a novel polyamides 6-1012 copolymers (PA6-1012) with different PA1012 salt loading. Experimental results show that the melting temperature (Tm), crystallization temperature(Tc), melting enthalpy(ΔHm), and crystallinity(Xc) decreased with the increase of PA1012 loading in the copolyamides. The size and number of the copolymers’ spherical crystals decrease by the additions of 1012 units, but its crystalline structure and thermal stabilities does not be affected. The hydrophilicity decreases with increasing PA1012 content from 0 to 28 wt% and the highest contact angle value at the PA1012 loading of 28 wt% is 96°, which can be considered as a surface hydrophobic material. Low temperature (−5 °C)mechanical test results reveal that loss in tensile strength is exchanged for a considerable increase in the strain at break. The impact strength of the PA6-1012 copolyamides is notably enhanced by increasing the PA1012 loading in different test temperatures due to the increase of molecular chain flexibility, indicating that the copolyamindes exhibit enough toughness to suitably apply in low temperature environment.

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion.

High-performance engineering thermoplastics offer lightweight and excellent mechanical performance in a wide temperature range. Their composites with carbon nanotubes are expected to enhance mechanical performance, while providing thermal and electrical conductivity. These are interesting attributes that may endow additional functionalities to the nanocomposites. The present work investigates the optimal conditions to prepare polyether ether ketone (PEEK)/multi-walled carbon nanotube (MWCNT) nanocomposites, minimizing the MWCNT agglomerate size while maximizing the nanocomposite electrical conductivity. The aim is to achieve PEEK/MWCNT nanocomposites that are suitable for melt-spinning of electrically conductive multifilament's. Nanocomposites were prepared with compositions ranging from 0.5 to 7 wt.% MWCNT, showing an electrical percolation threshold between 1 and 2 wt.% MWCNT (107-102 S/cm) and a rheological percolation in the same range (1 to 2 wt.% MWCNT), confirming the formation of an MWCNT network in the nanocomposite. Considering the large drop in electrical conductivity typically observed during melt-spinning and the drawing of filaments, the composition PEEK/5 wt.% MWCNT was selected for further investigation. The effect of the melt extrusion parameters, namely screw speed, temperature, and throughput, was studied by evaluating the morphology of MWCNT agglomerates, the nanocomposite rheology, and electrical properties. It was observed that the combination of the higher values of screw speed and temperature profile leads to the smaller number of MWCNT agglomerates with smaller size, albeit at a slightly lower electrical conductivity. Generally, all processing conditions tested yielded nanocomposites with electrical conductivity in the range of 0.50-0.85 S/cm. The nanocomposite processed at higher temperature and screw speed presented the lowest value of elastic modulus, perhaps owing to higher matrix degradation and lower connectivity between the agglomerates. From all the process parameters studied, the screw speed was identified to have the higher impact on nanocomposite properties.

Poly(arylene ether)s-Based Polymeric Membranes Applied for Water Purification in Harsh Environment Conditions: A Mini-Review.

Confronting the pressing challenge of freshwater scarcity, polymeric membrane-based water treatment technology has emerged as an essential and effective approach. Poly(arylene ether)s (PAEs) polymers, a class of high-performance engineering thermoplastics, have garnered attention in recent decades as promising membrane materials for advanced water treatment approaches. The PAE-Based membranes are employed to resist the shortages of most common polymeric membranes, such as chemical instability, structural damage, membrane fouling, and shortened lifespan when deployed in harsh environments, owing to their excellent comprehensive performance. This article presents the advancements in the research of several typical PAEs, including poly(ether ether ketone) (PEEK), polyethersulfone (PES), and poly(arylene ether nitrile) (PEN). Techniques for membrane formation, modification strategies, and applications in water treatment have been reviewed. The applications encompass processes for oil/water separation, desalination, and wastewater treatment, which involve the removal of heavy metal ions, dyes, oils, and other organic pollutants. The commendable performance of these membranes has been summarized in terms of corrosion resistance, high-temperature resistance, anti-fouling properties, and durability in challenging environments. In addition, several recommendations for further research aimed at developing efficient and robust PAE-based membranes are proposed.

SYNTHETIC PROTOCOLS AND SIGNIFICANCE OF HETEROCYCLIC FLUORESCENT - REINFORCING POLYMERS: A COMPREHENSIVE REVIEW

Fluorescent High-Performance polymers are well known as high performance engineering thermoplastics because of their good thermal stability, chemical resistance and excellent mechanical properties. Polymers having S-triazine ring become a subject of interest because of enhanced toughness and low moisture absorption and commercially available high performance engineering plastic materials. However, the thermal stability of triazine ring makes it an attractive monomer for use in high temperature polymers. Synthesis of polymers containing chromophoric groups which are responsible for fluorescent property have significant applications in fields such as biosensors, clean energy technologies, explosive sensing, pH/temperature sensor, biological imaging, life science, material science, ultrasensitive molecular diagnosis and novel light - emitting nano devices. The aromatic azo group is being more interest because of the existence of cis-trans isomerism and its effect on the photochromic properties of the polymers. Therefore, polymers having azo group have potential use in a variety of applications. Fluorescent polymers can be developed with different methods; generally, there are two methods for preparation of fluorescent polymers. One of them is polymerization of a monomer having a fluorescent chromophore such as fluorescent compounds as initiator, fluorescent compounds as chain transfer agents, chemical bonding between fluorescent groups and polymers. The second way, chemical alteration of commercially available polymers having reactive groups by using fluorescent dyes or organic molecules.

Effects of raster angle in single- and multi-oriented layers for the production of polyetherimide (PEI/ULTEM 1010) parts with fused deposition modelling

Abstract Material type and part deposition orientation are two important concerns in additive manufacturing. Additive manufacturing methods utilized by the industry are generally based on polylactic acid (PLA) or acrylonitrile butadiene styrene (ABS) materials using the fused deposition modelling (FDM) method. However, in present commercial applications, besides extensive use of PLA/ABS, their low strength has emerged as their biggest disadvantage. However, polyetherimide (PEI)/ULTEM 1010 parts represent high-performance engineering thermoplastics and offer superior mechanical properties with high thermal stability. On the other hand, selection of an appropriate raster angle orientation for single- and multi-oriented layers is also of considerable interest. A comprehensive study has been conducted herein on the building of a part using the FDM method using PEI/ULTEM 1010, and attempts have been made to identify the effects of raster angle in single- (0°, 30°, 45°, 60°, 90°) and multi-oriented (0/90°, 30°/−60°, 45°/−45°, 0°/90°/45°/−45°) layers. PEI specimens were manufactured via 3D printer, and the mechanical behaviour (tensile, bending and hardness) of the printed parts was correlated with their structures. Morphological properties of tensile fracture surface of 3D printed samples were analysed using scanning electron microscopy (SEM). Analysis indicated that a 0° part deposition orientation offers optimal mechanical properties because of the bonding structure.

UV-assisted direct ink write printing of fully aromatic Poly(amide imide)s: Elucidating the influence of an acrylic scaffold

High performance engineering thermoplastics exhibit excellent thermomechanical performance and chemical resistance, however, the rigid polymeric main chains that are derived from highly or fully aromatic repeating units impose processing challenges. The design of photo-reactive precursors now enables additive manufacturing of poly(amide imide) (PAI) precursor organo-gels via UV-assisted direct ink write (DIW) printing. Solution rheology revealed prerequisite high solution viscosities and shear thinning behavior of organic solutions of the PAI precursors. Additionally, photorheology of PAI precursors exhibited rapid gelation and high gel strengths, enabling production of self-supporting organo-gels that are necessary for successful DIW. Thermal post-treatment of the printed organo-gels revealed isotropic linear shrinkage as low as 26% during drying and imidization. The reduced chain rigidity of the poly(amide imide), relative to fully-aromatic polyimides, prevented quantitative thermal removal of the poly (hydroxyethyl acrylate) (poly(HEA)) scaffold, resulting in a decreased glass transition temperature (263 °C) relative to commercial PAI (290 °C). Moreover, crosslinking of the PHEA during thermal imidization limited scaffold removal upon solvent extraction, however, suggested the formation of novel multiphase polymers. Selective dissolution of the PAI from the crosslinked PHEA enabled assessment of the role of the scaffold on thermomechanical properties and characterization of printed PAI. Spectroscopic and thermal analysis confirmed the formation of the desired PAI composition with this photochemical synthetic method.

Laser Welding of Transmitting High-Performance Engineering Thermoplastics.

Laser processing is a rapidly growing key technology driven by several advantages such as cost and performance. Laser welding presents numerous advantages in comparison with other welding technologies, providing high reliability and cost-effective solutions. Significant interest in this technology, combined with the increasing demand for high-strength lightweight structures has led to an increasing interest in joining high-performance engineering thermoplastics by employing laser technologies. Laser transmission welding is the base method usually employed to successfully join two polymers, a transmitting one through which the laser penetrates, and another one responsible for absorbing the laser radiation, resulting in heat and melting of the two components. In this work, the weldability of solely transmitting high-performance engineering thermoplastic is analyzed. ERTALON® 6 SA, in its white version, is welded by a pulsed Nd:YAG laser. Tensile tests were performed in order to evaluate the quality of each joint by assessing its strength. A numerical model of the joint is also developed to support the theoretical approaches employed to justify the experimental observations.

Recent advances in additive manufacturing of engineering thermoplastics: challenges and opportunities.

There are many limitations within three-dimensional (3D) printing that hinder its adaptation into industries such as biomedical, cosmetic, processing, automotive, aerospace, and electronics. The disadvantages of 3D printing include the inability of parts to function in weight-bearing applications, reduced mechanical performance from anisotropic properties of printed products, and limited intrinsic material performances such as flame retardancy, thermal stability, and/or electrical conductivity. Many of these shortcomings have prevented the adaptation of 3D printing into product development, especially with few novel researched materials being sold commercially. In many cases, high-performance engineering thermoplastics (ET) provide a basis for increased thermal and mechanical performances to address the shortcomings or limitations of both selective laser sintering and extrusion 3D printing. The first strategy to combat these limitations is to fabricate blends or composites. Novel printing materials have been implemented to reduce anisotropic properties and losses in strength. Additives such as flame retardants generate robust materials with V0 flame retardancy ratings, and compatibilizers can improve thermal or dimensional stability. To serve the electronic industry better, the addition of carbon black at only 4 wt%, to an ET matrix has been found to improve the electrical conductivity by five times the magnitude. Surface modifications such as photopolymerization have improved the usability of ET in automotive applications, whereas the dynamic chemical processes increased the biocompatibility of ET for medical device materials. Thermal resistant foam from polyamide 12 and fly ash spheres were researched and fabricated as possible insulation materials for automotive industries. These works and others have not only generated great potential for additive manufacturing technologies, but also provided solutions to critical challenges of 3D printing.

Merging versatile polymer chemistry with multifunctional nanoparticles: an overview of crosslinkable aromatic polyester matrix nanocomposites.

The current trend in the global advanced material market is expeditiously shifting towards more lightweight, multifunctional configurations, considering very recent developments in electrical aircraft, biomedical devices, and autonomous automobiles. Hence, the development of novel polymer nanocomposite materials is critical to advancing the current state-of-the-art of structural material technologies to address the pressing performance demands. Aiming at expanding the existing material design space, we have investigated crosslinkable aromatic polyester matrix nanocomposites. Aromatic polyesters, in the thermosetting form, are a prospective high-performance/high-temperature polymer technology, which is on a par with conventional epoxy-derivative resins and high-performance engineering thermoplastics in the range of their potential applications. The aromatic matrix-based thermosetting nanocomposites manifest greatly enhanced physical properties enabled by a chemistry-favored robust interfacial covalent coupling mechanism developed during the in situ polymerization reaction with various nanofiller particle configurations. Here, we provide a summary review of our recent efforts in developing this novel polymer nanocomposite material system. We highlight the chemical strategy, fabrication approach, and processing techniques developed to obtain various nanocomposite representations for structural, electrical, optical, biomedical, and tribological applications. The unique characteristic features emerging in the nanocomposite morphologies, along with their physicochemical effects on the multifunctional macroscale properties, are demonstrated. This unique matrix configuration introduces superior performance elements to polymer nanocomposite applications towards designing advanced composite materials.

Effect of PS-g-MAH Content on ABS/PC Composites

Acrylonitrile-Butadiene-Styrene (ABS) is a common plastic which used in many fields with two-phase system Polycarbonate (PC) is a high-performance amorphous engineering thermoplastics. ABS/PC composites were researched in many academic papers and used in many fields. Polystyrene(PS) grafted with maleic anhydride (MAH)( PS-g-MAH) on ABS/PC composites is studied in this article. The tensile strength and elongation at break of ABS/PC blends have the maximum value when the content of PS-g-MAH is 3%. Tg of ABS in blends increase with the content of PS-g-MAH, which maybe induced by the increase of ABS/PC interface compatibility. From the photo of SEM, the addition of PS-g-MAH improves the compatibility of the interface of the two phases, leading to an increasing trend in the size of PC particles.

Advances in polyarylethers: opening new opportunities

High performance engineering thermoplastics are being extended to high-dimensional porous materials and sustainable biomass-driven materials.

Synergistic effects of short glass fiber/short carbon fiber hybrids on the mechanical properties of polyethersulfone composites

Polyethersulfone (PES) is one of important high performance engineering thermoplastics but its mechanical and tribological properties are not comparable to those of metals and have to be enhanced in order to widen its applications. In this work, both short glass fibers (SGFs) and short carbon fibers (SCFs) are employed to reinforce PES and the SCF/SGF/PES composites were prepared using melt blending and injection molding techniques. The simultaneous usage of SCFs and SGFs with various volume ratios is to examine their possible synergistic effects in reinforcing PES. The results reveal that the tensile and flexural properties as well as wear resistance are all enhanced by the addition of both SCFs and SGFs. The tensile/flexural strength and modulus of the hybrid PES composites increase with increasing the SCFs volume fraction in fillers. Meanwhile, the friction coefficient and specific wear rate of the hybrid PES composites decrease with increasing the SCFs volume fraction in fillers. Interestingly, the tensile strength, flexural strength and wear resistance of the hybrid SCF/SGF/PES composites at proper SCF/SGF volume fraction ratios are obviously higher than those predicted by the rule of mixtures, representing the typical positive synergistic effects of SCFs and SGFs. Consequently, it is promising to employ both expensive SCFs and cheap SGFs at proper SCF/SGF volume fraction ratios for reinforcing PES in considering the combination of properties and cost. POLYM. COMPOS., 40:E1725–E1731, 2019. © 2018 Society of Plastics Engineers

Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers.

Phenolphthalein‐based cardo poly(arylene ether sulfone): Preparation and application to separation membranes

AbstractCardo poly(arylene ether sulfone)s are an important type of high performance engineering thermoplastics. They possess unique properties, including good processability, thermal stability, and good insulating and mechanical properties as well as excellent chemical resistance. They are potential candidates for the preparation of ion exchange, water purification, and gas separation membranes. This review focuses on the synthesis of phenolphthalein‐based cardo poly(arylene ether sulfone)s, including synthesis of cardo bisphenols and their polymers, and their application to separation membranes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A Simple and Selective Biphasic Catalytic System for the Oxidative Polymerization of 2,6-Dimethylphenol

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) is widely used in high-performance engineering thermoplastics and thus, it is economically attractive. An effective catalytic procedure has been developed, consisting of a toluene/water solvent mixture in which the oxidative coupling of 2,6-dimethylphenol (DMP) is performed. This biphasic system allows an easy separation of the polymer from the copper catalyst.

High glass transitions of high-performance thermoplastics

Demand of high-performance engineering thermoplastics in industrial countries drives the development of this class of materials in over 30 years. They display high heat distortion temperature, high modulus and strength, dimensional stability, chemical resistance, inherent flame retardancy and share the commonality of high glass transition. The observed variations of T g with composition are compared with the postulated using Van Krevelen's structural group contribution theory. The predicted T g does not differentiate the variations affected by moisture and crystallinity. The `wet' T g's are determined by modulated temperature-DSC (MT-DSC), while the `dry' or the constained T g due to orientation and/or annealing is detectable by standard DSC. The glass transitions of the constrained domains in highly crystalline polymers can be followed by DMA, DEA and thermal expansibility.

Self‐Reinforced composites of two thermotropic liquid crystalline polymers

AbstractBlends of two thermotropic liquid crystalline polymers (LCP) based on 6‐oxy‐2‐naphthoyl and p‐oxybenzoyl moieties and p‐oxybenzoyl, terephthaloyl and hydroquinone moieties have been studied. The blends were prepared by melt mixing using a twin screw extruder. Thermal, rheological, mechanical, and morphological studies were carried out. Based on the dynamic mechanical thermal analysis and the morphological observations, the blends are found to be immiscible. The viscosity ratios of pure LCP melts exceed values of 10 over a wide range of shear rates, with the viscosity of the blends lying between those of the pure components. The prepared blends are shown to be self‐reinforced composites in which one LCP enhances the molecular orientation of the other. Studies of the injection molded bars by scanning electron microscopy indicate a complicated hierarchical morphology with microfibrils of submicron level in diameter, bundled, and intertwined into fibrils of a substantially larger diameter. Due to self reinforcement, impact and tensile properties of the blends show significant synergism when compared to those of the pure LCP components. The properties obtained are remarkably higher than those known for any high performance engineering thermoplastics.

Miscible Blends of Poly(siloxane Imide) Segmented Copolymers and Polybenzimidazole as Potential High Performance Aerospace Materials

Compatible blends of high performance engineering thermoplastics have been investigated for aerospace applications, where stability in an aggressive atomic oxygen environment is of significant concern. The blends were comprised of polyimide homopolymers and poly(siloxane imide) segmented copolymers based upon benzophe-none tetracarboxylic dianhydride (BTDA) and m-diaminodiphenyl sulfone, and polybenzimidazole (PBI). The blends exhibited glass transition temperatures in excess of 300°C, and significantly reduced water sorption relative to PBI. Conversion of the siloxane surface to an inorganic, oxidation resistant silicate in the presence of atomic oxygen accounted for the enhanced stability of siloxane-containing blends to a simulated low earth orbit environment.

Friction and wear studies of a short glass-fibre-reinforced polyetherimide composite

Polyetherimide, commercially known as ULTEM resin, is one of the newest high performance engineering thermoplastics. It has a unique combination of thermal, mechanical and electrical (insulating) properties. Its glass-fibre-reinforced (20%) composite has still better mechanical properties and has been studied in the present work to evaluate its potential as a tribological material. Tribological studies were carried out on a tri-pin-ondisc machine against mild steel as a counterface at various loads, surface roughnesses and speeds. The specific wear rate was found to be comparable with that of commercially available bearing materials. However, the friction coefficient was high and slightly unsteady. Scanning electron microscopy studies were done to investigate the wear mechanisms.