Search

The friction and wear behavior of sliding bearings made from high temperature thermoplastics was investigated to determine the possibility of dry sliding applications. A test apparatus for plain bearing testing was designed and built to enable load, speed, and temperature to be controlled and temperature, friction and wear to be continuously monitored. Bulk material bearings (polyaryletherketone-based composites and neat polybenzimidazole) and metal-thermoplastic compound bearings with a sliding layer of polyetheretherketone were investigated. Their suitability for dry sliding bearing applications was assessed using the values of friction coefficient, wear rate and friction induced temperature. In general, the operating performance is mainly influenced by the operating conditions and the precise construction of the bearing. A fiber reinforcement of the thermoplastic matrix is necessary at high loads, whereas it is unnecessary at low loads. A further increase of the operational limits is made possible by improving the heat conduction from the contact area, as comparison with results of pin-on-disk investigations indicates. The materials tested provide operation of dry sliding bearings to temperatures over 200°C.

This chapter focuses on high-temperature, high-performance plastics. Chemical structures with effects of weathering, common stabilizers, manufacturers and trade names along with typical end uses of the plastics are included besides extensive tabular and graphical physical, mechanical, electrical and thermal properties before and after various weathering processes. Plastics included in this section are polyether ether ketone, polyaryletherketone, polyphenylene sulfide, polyphenylsulfone, polyethersulfone, polysulfone, Parylene (poly(p-xylylene)) and polyoxymethylene (acetal homopolymer)/polyoxymethylene copolymer (acetal copolymer).

Amorphous blends from a deuterated polyaryletherketone and a polyetherimide have been prepared and investigated by neutron scattering. The used components differ remarkably in their structure antheir solution properties. The blends on the other hand are combinatorial mixtures : the scattering quantity Φ 1 Φ 2 /S(q) is independent of the composition of the blends if the polymer chains have the same length

The non-isothermal crystallization kinetics of polyphenylene sulfide (PPS) and its blends with polyaryletherketone-bearing phthalidylidene group (PEK-C) was investigated by differential scanning calorimetry. The experimental data were evaluated quantitatively. It was found that the blend of PPS incorporating 10 wt% PEK-C has the maximum crystallizability. The mechanism involved in the effect of PEK-C on PPS crystallization behaviour is proposed.

Publisher Summary This chapter introduces a paradigm for the design of bioactive polyaryletherketone PAEK composites for biomedical devices. The clinical and commercial success of PAEK implants in interbody spinal fusion was enabled by several advantageous properties. PAEK polymers are generally biocompatible, bioinert, and radiolucent; PAEK polymers also exhibit a high strength and similar compliance to bone. The design of bioactive PAEK composites is considered within the framework of processing–structure–property relationships common to materials science and engineering. The processing, structure, and properties of the materials used in a biomedical device have great influence on the device performance. PAEK composites can be prepared by compounding and injection molding, cold pressing and pressureless sintering, compression molding, and selective laser sintering. The latter three methods can also be used to produce macroporous PAEK scaffolds. Each method has its own advantages and disadvantages. Compounding and injection molding is amenable to low-cost, high-volume commercial manufacturing of net shapes with a dense microstructure. Standard PAEK beads for injection molding may be used since bioactive reinforcements are mixed into the molten polymer by shear flow during compounding. Cold pressing and pressureless sintering require low overhead equipment costs and are amenable to almost any level of reinforcement during processing. Compression molding is similar to injection molding in relatively low-cost, high-volume commercial manufacturing of net shapes with a dense microstructure, except that production rates are slightly lower and machining may be required to attain nongeometric shapes. Numerous gaps in the current state of knowledge for bioactive PAEK composites have been noted.

This chapter focuses on high-temperature and high-performance plastics. Chemical structures, manufacturers, and trade names along with typical end uses of the plastics are included besides extensive tabular and graphical physical, mechanical, electrical, and thermal properties before and after various sterilization processes. Plastics included in this section are polyether ether ketone, polyaryletherketone, polyphenylene sulfide), polyethersulfone, polysulfone, polyphenylsulfone, polybenzimidazole, Parylene (poly( p -xylylene)), polyoxymethylene (acetal homopolymer)/polyoxymethylene copolymer (acetal copolymer), and self-reinforced polymers.

Publisher Summary This chapter reviews basic information about polymers in general and describes the structure and composition of polyaryletheretherketone (PEEK). It is a member of the polyaryletherketone polymer (PAEK) family that has been used for orthopedic and spinal implants. Historically, the availability of PEEK arrived at a time when there was a growing interest in the development of “isoelastic” hip stems and fracture fixation plates, with stiffnesses comparable with the bone. Much of the research on PEEK implants has been fragmented in the materials science, composites, biomaterials, and application-specific literature. PEEK had emerged as the leading high-performance thermoplastic candidate for replacing metal implant components, especially in orthopedics and trauma. Numerous studies have documented the successful clinical performance of PAEKs in orthopedic and spine patients. Recent research has also investigated the biotribology of PEEK composites as bearing materials and flexible implants used for joint arthroplasty. Because of the interest in further improving implant fixation, PEEK biomaterials research has also focused on compatibility of the polymer with bioactive materials, including hydroxyapatite, either as a composite filler or as a surface coating. As a result of ongoing biomaterials research, PEEK and related composites can be engineered today with a wide range of physical, mechanical, and surface properties, depending upon their implant application.

Polyaryletheretherketone (PEEK) is a challenge to synthesize and convert into surgical implants. The polymer is chemically inert and insoluble in all conventional solvents at room temperature. PEEK can only be completely dissolved using fairly esoteric solvents, such as diaryl sulfones. Although inertness and insolubility are desirable for a biomaterial, these attributes constrain the synthesis and manufacture of PEEK. There are various synthetic routes involved in the production of polyketone-based materials. These routes have been developed to overcome the initial challenges in relation to polyketone manufacturing, resulting in the consistent production of polymers for medical applications. The synthetic chemistry used in polyaryletherketone (PAEK) manufacture has a major influence on the thermal stability of the polymer in processing operations and on the leachable and volatile content of these polymers. Therefore, the manufacturing route has the potential to alter the biocompatibility of PAEK materials. The progress in manufacturing has been extended to processing where established methods have been developed to allow the production of reproducible components from a range of production techniques such as injection molding or machining of stock shapes. The relatively recent addition of a biomedical focus to manufacturing and supply offers device companies an opportunity to use these PEEK-based materials, in implants, with confidence in the quality and security of supply.

Various polyaryletherketone-based composites were investigated with regard to their high temperature dry-sliding behaviour. In the range between room temperature and 220 °C, all grade with a polytetrafluoroethylene (PTFE) content of 10–15 wt.% exhibited a friction behaviour that is very similar to that of neat PTFE. Studies of the wear-pv relationship of some of the grades showed that fibre contents of 30 wt.% are found to stabilize the specific wear, up to pv products of 16 MPa m s−1.

Publisher Summary This chapter presents information and multipoint properties for several high-temperature, high-performance plastics, grouped together because of their performance levels. Polyetheretherketones, also referred to as polyketones, is a thermoplastic with extraordinary mechanical properties. The material is also resistant to both organic and aqueous environments, and is used in bearings, piston parts, pumps, compressor plate valves, and cable insulation applications. It is one of the few plastics compatible with ultrahigh vacuum applications. Polyethersulfone (PES) is an amorphous polymer and high temperature engineering thermoplastic. Even though PES has high temperature performance, it can be processed using conventional plastics processing equipment. PES has an outstanding ability to withstand exposure to elevated temperatures in air and water for prolonged periods. Polyphenylene Sulfide (PPS) is a semicrystalline material. It offers an excellent balance of properties, including high temperature resistance, chemical resistance, flowability, dimensional stability, and electrical characteristics. PPS must be filled with fibers and fillers to overcome its inherent brittleness. Polysulfone (PSU) is a rigid, strong, tough, high-temperature amorphous thermoplastic. It has a high heat deflection temperature. Polybenzimidazole (PBI) is a unique and highly stable linear heterocyclic polymer. PBI exhibits excellent thermal stability, resistance to chemicals, acid and base hydrolysis, and temperature resistance.

This chapter focuses on high temperature and high-performance plastics. Chemical structures with manufacturers and trade names along with typical end uses of the plastics are included besides extensive graphical, physical, mechanical, and electrical as a function of temperature. Plastics included in this section are polyether ether ketone, polyaryletherketone, polyether ketones, polyether ketone ether ketone ketones, polyphenylene sulfide, polyphenylsulfone, polyethersulfone, polysulfone, Parylene (poly(p-xylylene)), and polyoxymethylene (acetal homopolymer)/polyoxymethylene copolymer (acetal copolymer).

Host polymers play an important role in determining the thermal, optical and electrical properties of guest-host electro-optic (EO) polymers. In this study, a series of novel polymers, polyaryletherketones (PEKs) and polyarylethersulfones (PES'), were synthesized. After an initial screening on EO modulator fabrication-related properties, a PEK, LP120, was identified as a good candidate to host the highly stable chromophores (DH6 and DH52) developed in the company. Further optimization indicated that solvents in chromophore/polymer solutions have a strong impact on the quality of spin-coated films. DH6/LP120 and DH52/LP120 films spun from cyclopentanone gave lower optical losses of 1.97 and 1.55 dB/cm, respectively, when compared with 2.84 dB/cm for DH6/APC and 1.96 dB/cm for DH52/APC. Moreover, poling efficiencies as being reflected by EO coefficient were also improved by using LP120 compared to APC.

Publisher Summary This chapter opens with a general discussion of various types of joining techniques in context to Ultrapek high-heat resistant polyaryletherketone (PEEK) polymer. Dissoluble or indissoluble bonds can be formed by various means among Ultrapek parts and parts produced from the same or other materials. Ultrapek can be welded by heated-tool, vibration, spin and ultrasonic techniques. High frequency welding is not feasible, owing to Ultrapek's low dissipation factor. Heated-tool welding is mainly resorted to for assembling large parts, e.g. tubes and sheet. Ultrapek demands high heatedtool temperatures, for which conventional nonstick coatings are unsuitable. It can be welded by heated-tool, vibration, spin and ultrasonic techniques. High frequency welding is not feasible, owing to Ultrapek's low dissipation factor. The adhesives used for bonding Ultrapek articles to other articles produced from Ultrapek or another material may be based on epoxy resins, cyanoacrylates, polyurethanes, silicones, or other polymers. Examples of other techniques for increasing the bond strength are plasma treatment or etching with potassium dichromate/sulfuric acid solution.

Novel rare earth-coordinated polymers were prepared using carboxyl-containing polyaryletherketone (PEK) as the macromolecular ligand and 8-hydroxyquinoline (HQ) as the co-ligand to coordinate with erbium (Er3+), neodymium (Nd3+) and ytterbium (Yb3+), respectively. The FTIR, elemental analysis, inductively coupled plasma, and UV-vis results confirm that the rare earth ions have been attached to the polymer backbone via a coordination bond. The complexes can emit the characteristic near-infrared fluorescence of the corresponding rare earth ions. Moreover, it is found that the synergistic effect of PEK and HQ can significantly enhance the emission intensities. In particular, for PEK-Er3+-HQ, the full width at half maximum (FWHM) of the 4I13/2→4I15/2 transition is up to 78 nm. The combination of strong fluorescence emission in the near-infrared range, high glass transition temperature and wide gain bandwidth provides promising potential for optical amplification applications.

Amorphous blends from a deuterated polyaryletherketone and a polyetherimide have been prepared and investigated by small-angle neutron scattering (SANS). The blends are combinatorial mixtures: the scattering quantity Φ1Φ2/S(q) is independant of the composition of the blends.

The present investigation deals with an attempt to improve the toughness of polyphenylene sulfide (PPS) through blending with a China - made polyaryletherketone (PEK - C). It is found that on certain processing conditions PPS can be made very tough in the case of lower PEK - C content. On the basis of mechanical performance measurement and fractographic analysis, the toughening mechanism is discussed tentatively.

We have studied the structure and morphology of the useful high‐temperature/high‐strength polymer polyaryletherketone (PEEK) by transmission electron microscopy and three‐dimensional electron diffraction after finding suitable solvents (α‐chloronaphthalene and benzophenone) that allowed casting of the required ultrathin polymer films. When crystallized from the melt, PEEK grows in the form of spherulites consisting of narrow lamellae and having the b axis of the unit cell radial. Additionally, at high temperatures in these ultrathin films, the spherulites attain an extraordinary cylindrical symmetry as a result of growth of their lamellae on edge, with the c crystallographic direction parallel to the film plane and the a direction corresponding to the cylinder axis. Reasons for this mode of growth are attributed to the highly anisometric molecular cross section normal to the chain direction, which favors crystal nucleation on the substrate with the bc plane. At lower temperatures during crystallization from the melt, a more random lamellar disposition is seen in these thin‐film spherulites, although lamellae on edge still predominate. Crystallization by heating from the quenched glassy phase yields random lamellar aggregates and small spherulites. The glassy phase in ultrathin PEEK shows no consistent morphological features down to a level of resolution of 1.0 nm. Scanning electron microscopic examination of the free surfaces of bulk samples crystallized under controlled conditions both from the melt and from the glass, show that our findings from ultrathin films (with the exception of the quasicylindrical spherulitic substructure) also apply to these thicker specimens.

4 pags.3 figs., Poly-p-phenilene, prepared in laboratory, commercial poly-p-phenylene sulphide and two new high temperature thermoplastic polymers (polyarylethersulphone and polyaryletter ketone) have been doped by means of SbCl5. Measurements of electrical conductivity at room temperature carried out in situ as a function of doping time are reported.

Polyaryletherketones were reported independently by ICI and du Pont [1,2] in the patent literature as novel materials at about the same time as the corresponding polyethersulphones in the early 1960s. It is likely therefore that these discoveries arose from scientific and technological considerations similar to those detailed in the previous chapter for the polyethersulphones except that the polyketone inventors were probably looking for fibre forming polymers as Goodman et. al. [1] were working in the Fibres Division of ICI and Bonner [2] reported drawing fibres from a melt of one of his polymers. Union Carbide was also interested in polyetherketones at this time and exemplified a polyaryletherketonesulphone and a polyaryletherketone containing a bis-phenol. A residue in the repeat unit in the British Patent [3] describing their polyether synthesis and concerned mainly with polyarylethersulphones.