High-performance Thermoplastics Research Articles

Incompatible blends of liquid crystalline polymers and engineering thermoplastic

The increasing demand of the high technology market for new applications in the aerospace industry has led to research on high performance thermoplastics as composite matrices. The inclusion of solid fibres in this class of materials during manufacturing may result in processing conditions that are too demanding. High temperature and pressure in stamping or injecting tools may result in thermal degradation of the organic matrix. Moreover, the load transfer through the fibre–matrix interface produces fibres breaking into fragments shorter than the critical length, affecting their aspect ratio, and consequently reducing the final performance of the product. The possibility of producing the reinforcing filler during the cooling cycle of the composite processing has suggested the definition of 'in situ' composite. In this paper the addition of thermotropic liquid crystalline polymer to engineering thermoplastics has been investigated. X–ray diffraction techniques have been used to evaluate the molecular orientation of the dispersed phase. The rheology and the mechanical properties of the in situ composites is related to the morphology of the material and to the processing operations.

Tailoring surface nanostructures on polyaryletherketones for load-bearing implants

High-performance thermoplastics including polyetheretherketone (PEEK) are key biomaterials for load-bearing implants. Plasma treatment of implants surfaces has been shown to chemically activate its surface, which is a prerequisite to achieve proper cell attachment. Oxygen plasma treatment of PEEK films results in very reproducible surface nanostructures and has been reported in the literature. Our goal is to apply the plasma treatment to another promising polymer, polyetherketoneketone (PEKK), and compare its characteristics to the ones of PEEK. Oxygen plasma treatments of plasma powers between 25 and 150 W were applied on 60 μm-thick PEKK and 100 μm-thick PEEK films. Analysis of the nanostructures by atomic force microscopy showed that the roughness increased and island density decreased with plasma power for both PEKK and PEEK films correlating with contact angle values without affecting bulk properties of the used films. Thermal analysis of the plasma-treated films shows that the plasma treatment does not change the bulk properties of the PEKK and PEEK films.

Mass Appeal

Plastics EngineeringVolume 69, Issue 7 p. 6-14 Cover Story Mass Appeal High-performance thermoplastics spark automakers' relentless drive to reduce weight and increase fuel economy Pat Toensmeier, Pat ToensmeierSearch for more papers by this author Pat Toensmeier, Pat ToensmeierSearch for more papers by this author First published: 01 July 2013 https://doi.org/10.1002/j.1941-9635.2013.tb01034.xCitations: 1AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume69, Issue7July-August 2013Pages 6-14 RelatedInformation

Influence of the Degree of Crystallinity on the Mechanical and Tribological Properties of High-Performance Thermoplastics Over a Wide Range of Temperatures: From Room Temperature up to 250°C

The mechanical characteristics of block-shaped samples of a number of thermally stable thermoplastics for structural applications are investigated over a wide range of temperatures: from the room temperature (RT) up to 250°C. Together with several commercially available materials, namely, polyetheretherketone, polyphenylene sulfide, and a polyetherimide Ultem-1000; a number of polyimide thermoplastics designed at the Institute of Macromolecular Compounds RAS having both semicrystalline and amorphous structures were studied. The tribological behavior of these thermoplastics was investigated in the tribometers of different types using polymer–steel couples with the variation of both the temperature (from RT to 250°C) and the contact pressure. The experimental determination of the overheating values of the contact surface of the polymer sample was carried out during the friction process at different medium temperatures. The possibilities of obtaining a maximally broad temperature range for applications of thermoplastic polymeric material by regulating the degree of its structural ordering are analyzed.

Random copolymer of styrene and diene derivatives via anionic living polymerization followed by intramolecular Friedel–Crafts cyclization for high-performance thermoplastics

Rubbery random copolymers of styrenes and dienes prepared via anionic living polymerizations were intramolecularly cyclized into high-performance thermoplastics.

Experimental analysis of drilling damage in carbon-fiber reinforced thermoplastic laminates manufactured by resin transfer molding

The emergence of new high-performance thermoplastics to replace thermosets in fiber-reinforced polymers puts up a new challenge: their machining. In this study, carbon fiber-reinforced poly-cyclic butylene terephthalate laminates were manufactured, drilled, and inspected. Different commercial drill geometries and machining conditions were compared. Roughness, microscopy, and non-destructive tests allowed us to determine the hole quality as well as delamination. The surface tests showed better results after working at the most common cutting speed (3000 rpm) than at high speed (15,000 rpm) with a constant feed rate. This fact can be explained based on the viscoelastic properties of the matrix that becomes fragile at high cutting speeds. The Delamination factor obtained by means of Ultrasonics and X-ray Computed Tomography also confirmed that the best results are achieved with a Twist drill bit at 3000 rpm. In contrast to carbon fiber-reinforced thermosets, the detected delamination at high cutting speeds is not as remarkable as expected. These results allow us to conclude that this new composite will certainly increase production rate without delamination damage. Chip formation takes also a special role. It can be recovered to be used as reinforcement in manufacturing processes due to the recyclability of the thermoplastic matrix.

Enhanced Continuous Glass Fibre-Reinforced Poly(phthalazinone ether sulfone ketone) Composites by Blending Polyetherimide and Polyethersulfone

Poly(phthalazinone ether sulfone ketone) (PPESK) is a novel high performance thermoplastic with outstanding high temperature resistance and excellent mechanical properties and therefore, it is a very ideal candidate matrix for advanced composites. However, the high melt viscosity of PPESK makes it difficult to melt-process. In this paper, two well-known high performance thermoplastics, polyetherimide (PEI) and polyethersulfone (PES) were introduced into PPESK in order to reduce its melt viscosity and to improve the properties of its composites. The effect of the addition of PEI and PES on the resultant composites was studied. A series of unidirectional composites was made from PPESK and its PEI and PES blends as matrices and continuous glass fibre as reinforcement. The solution prepregging method and hot-press moulding method were used in the preparation of composites. The effects of the polymer blend matrices on the mechanical properties, interfacial adhesion and fracture mode were studied by three point bending, interlaminar shearing, porosity measurements and SEM microscopy. The results showed that the mechanical properties and interfacial adhesion increased and the porosity decreased after blending PEI or PES in the matrix. Addition of PEI and PES to PPESK also resulted in an obvious transition of fracture mode.

New hybrid nanocomposites containing carbon nanotubes, inorganic fullerene-like WS2 nanoparticles and poly(ether ether ketone) (PEEK)

Single-walled carbon nanotubes (SWCNTs) and inorganic fullerene-like WS2 nanoparticles were successfully dispersed in poly(ether ether ketone) (PEEK) by advantageously traditional melt processing techniques. This strategy offers an attractive way to combine the merits of organic and inorganic materials into novel hybrid systems that challenge emerging polymer/CNT nanocomposites in terms of performance, cost and processability. In particular, the incorporation of IF-WS2 has shown to be efficient to produce well-dispersed PEEK/SWCNT composites influenced in turn by the processing method. The morphology, thermal stability, crystallization behaviour, thermal conductivity as well as mechanical and electrical properties of PEEK/SWCNT composites were tuneable by the introduction of small amounts of IF-WS2. The overall structural, thermal, mechanical and electrical performances confirm the potential use of SWCNTs and IF-WS2 for the preparation of advanced hybrid nanocomposites as lightweight alternatives for use in critical industrial applications of high-performance and high-temperature thermoplastics like PEEK.

Microstructure and mechanical properties of flame-sprayed PEEK coating remelted by laser process

Poly-ether-ether-ketone (PEEK) is one of the high-performance thermoplastics. It is being increasingly used for many industrial applications due to its excellent properties. In this paper, a flame spraying technique is used to deposit PEEK coating on 304L stainless substrates. CO 2 and Nd:YAG laser treatments are chosen to remelt the as-sprayed polymer coating to get a dense coating. The microstructures of the as-sprayed and remelted coatings are characterized by SEM and XRD. The results show that both CO 2 and Nd:YAG lasers are suitable for densifying the PEEK coating on stainless substrate. However, the remelted coatings present different crystalline structure due to their laser processing parameters. Hardness measurements, tribological and scratch tests are conducted to characterize the mechanical properties of remelted coating. The coatings’ mechanical properties are correlated with their structures.

Modified continuous carbon fiber‐reinforced poly(phthalazinone ether sulfone ketone) composites by blending polyetherimide and polyethersulfone

AbstractPoly(phthalazinone ether sulfone ketone) (PPESK) is a novel high performance thermoplastic with outstanding high temperature resistance and excellent mechanical properties and therefore, it is a very ideal candidate matrix for advanced composites. However, its high melting viscosity makes the melting process difficult. In this article, two well‐known high performance thermoplastics, polyetherimide (PEI) and polyethersulfone (PES) were introduced to PPESK in order to reduce the melting viscosity of PPESK and to improve the properties of composites. The effect of addition of PEI and PES on the resultant composites was studied. A series of unidirectional composites were made of PPESK and its PEI and PES blends as matrix and continuous carbon fiber (T700) as reinforcement. The solution prepregging method and hot‐press molding method were used in preparation of composites. The effects of polymer blends matrix on mechanical properties, interfacial adhesion, and fracture mode were studied by three points bending, interlaminar shearing, porosity, and scanning electron microscope test. The results show that the mechanical properties and interfacial adhesion increases, and the porosity decrease after blending PEI or PES in the matrix. Addition of PEI and PES to PPESK results in an obvious transition of fracture mode. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

High-Performance Thermoplastics

Plastics EngineeringVolume 63, Issue 6 p. 18-22 Europe High-Performance Thermoplastics Peter Mapleston, Peter MaplestonSearch for more papers by this author Peter Mapleston, Peter MaplestonSearch for more papers by this author First published: 01 June 2007 https://doi.org/10.1002/j.1941-9635.2007.tb00131.xAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume63, Issue6June 2007Pages 18-22 RelatedInformation

Environmentally degradable, high-performance thermoplastics from phenolic phytomonomers

Aliphatic polyesters, such as poly(lactic acid), which degrade by hydrolysis, from naturally occurring molecules form the main components of biodegradable plastics. However, these polyesters have become substitutes for only a small percentage of the currently used plastic materials because of their poor thermal and mechanical properties. Polymers that degrade into natural molecules and have a performance closer to that of engineering plastics would be highly desirable. Although the use of a high-strength filler such as a bacterial cellulose or modified lignin greatly increases the plastic properties, it is the matrix polymer that determines the intrinsic properties of the composite. The introduction of an aromatic component into the thermoplastic polymer backbone is an efficient method to intrinsically improve the material performance. Here, we report the preparation of environmentally degradable, liquid crystalline, wholly aromatic polyesters. The polyesters were derived from polymerizable plant-derived chemicals--in other words, 'phytomonomers' that are widely present as lignin biosynthetic precursors. The mechanical performance of these materials surpasses that of current biodegradable plastics, with a mechanical strength, sigma, of 63 MPa, a Young's modulus, E, of 16 GPa, and a maximum softening temperature of 169 degrees C. On light irradiation, their mechanical properties improved further and the rate of hydrolysis accelerated.

Impact-Modified Poly(ethylene terephthalate)/Polyethylene-Octene Elastomer Blends

Poly(ethylene terephthalate) (PET) is a low cost, high performance thermoplastics. However, its shortcoming is that it has poor impact-strength properties. High-impact strength PET was prepared using polyethylene-octene elastomer (POE) grafted with a toughener, maleic anhydride. The effect of the maleate compatibilizer on the interfacial adhesion and impact-strength properties of PET/POE blends was investigated through impact testing, scanning electron microscopy (SEM) observation, and rheological behavior analysis. The results showed that unmodified POE has hardly any contribution to the toughness of PET, whereas maleic anhydride-grafted POE (POE-g-MA) significantly improves the compatibility of POE and PET. The size of POE-g-MA particles in the PET matrix were sharply reduced due to interaction between POE-g-MA and PET during melt processing.

AFM approach toward understanding morphologies in toughened thermosetting matrices

Atomic force microscopy, AFM, has been used for determining the microstructure of thermosetting matrices toughened by incorporation of core-shell particles and high-performance thermoplastics. A variety of systems has been considered in this work: one group is based on diglycidyl ether of bisphenol-A (DGEBA) epoxy matrix, and the other group is based on bisphenol-A dicyanate (DCBA) matrix. The studied epoxy systems were: DGEBA cured with an aromatic hardener, diamino diphenyl sulfone (DDS), and modified with polymethylmethacrylate (PMMA), or cured with a cycloaliphatic hardener, diamino dimethyl cyclohexylmethane (3DCM), and modified with core-shell particles of polystyrene-co-butylacrylate (PS-co-Bu). The DCBA-based matrices have been modified with polysulfone of bisphenol-A (PSU) or with polyetherimide (PEI). The influence of the modifiers and the curing conditions on the generated morphologies is reported as analysed by AFM in contact and tapping modes.

Microcellular foams from polyethersulfone and polyphenylsulfone: Preparation and mechanical properties

Polymeric foams having microcellular structures were successfully prepared from some high-performance thermoplastics, specifically polyethersulfone and polyphenylsulfone. A two-stage batch foaming process was used and the resulting materials had average cell sizes in the range 2–13 μm, and cell densities the order of 10 10–10 11 cells/cm 3. The foam densities (relative to those of the unfoamed polymers) were in the range 0.90–0.35. Average cell sizes increased with foaming temperature and foaming time; on the other hand, cell densities and relative foam densities decreased slightly with foaming temperature but remained almost constant with foaming time. Experimental values of Young’s modulus in compression and the elastic collapse strength were higher than theoretically predicated at high relative densities, but the discrepancies became small at lower densities. In contrast, Young’s moduli in tension were in very good agreement with theory, but the relative strengths were somewhat lower than predicated.

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-Temperature Polymers for Advanced Microelectronics

Several series of aromatic polyethers and polybenzoxazoles with high thermal stability and low dielectric constant were prepared and characterized. The polyethers were synthesized by nucleophilic aromatic displacement of fluorine with phenoxides. In order to avoid strongly polar groups such as carbonyl and sulfone, trifluoromethyl groups were used to activate the fluorine for displacement. An additional benefit of the presence of the trifluoromethyl groups is the decreased dielectric constant, which fluorinated materials exhibit. This is attributed to two factors: the strong electronegativity of fluorine, resulting in very low polarizability of the C–F bonds, and the larger radius of a fluorine atom in comparison with a hydrogen atom, resulting in increased free volume. Trifluoromethyl substituted terphenyl and quadriphenyl poly(arylether)s prepared in this study exhibit decomposition temperatures far in excess of 500°C, even in air, dielectric constants below three, and mechanical properties comparable to engineering plastics such as polycarbonate and high-performance thermoplastics such as PEEK. Poly(benzoxazole)s were prepared with and without fluorine substituents. Since most of the poly(benzoxazole)s were insoluble, they were prepared via soluble poly(hydroxyamide) precursors, which were converted to the final polymers by thermal treatment. These materials had dielectric constants as low as 2.69 and also decomposition temperatures far above 500°C in air.

Synthesis and properties of novel random and block copolymers composed of phthalimidine- and perfluoroisopropylidene-polyarylether-sulfones

A series of novel polyarylethersulfone (AB)(n) block copolymers with different segment lengths have been synthesized by nucleophilic solution polycondensation of phenoxide-terminated and fluorine-terminated oligomers; random copolymers have been prepared over the whole composition ranges. The structures of the resultant copolymers have been confirmed by FTIR, C-13 NMR spectra and differential scanning calorimetry (DSC). Compared with two homopolymers and random copolymers, the block copolymers of this study possess excellent thermal stability (5% thermal decomposition under nitrogen atmosphere above 500 C) and high glass transition temperatures, and have a wide melt-processing temperature range. They may become a new class of mouldable high performance thermoplastics. (C) 2001 Society of Chemical Industry.

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.

Physical aging of high‐performance thermoplastics: Enthalpy relaxation in PEK‐C and PES‐C

AbstractThe developments of physical aging in phenolphthalein poly(aryl‐ether‐ketone) (PEK‐C) and poly(aryl‐ether‐sulfone) (PES‐C) with time at two aging temperatures up to 20 K below their respective glass transition temperatures (Tg = 495 and 520 K) have been studied using differential scanning calorimetry (DSC). Substantial relaxation within the aging course of several hours were observed by detecting (Tg) decreasing during physical aging process at the two aging temperatures. The relaxation processes of both polymers are extremely nonlinear and self‐retarding. The time dependencies of their enthalpies during the initial stages of annealing were approximately modeled using the Narayanaswamy‐Tool model. The structure relaxation parameters obtained from this fitting were used to predict the possibility of physical aging occurring at their respective using temperatures. © 1995 John Wiley & Sons, Inc.