Thermoplastic Polyphenylene Sulfide Research Articles

A New Strengthening Process for Carbon-Fiber-Reinforced Thermoplastic Polyphenylene Sulfide (CFRTP-PPS) Interlayered Composite by Electron Beam Irradiation to PPS Prior to Lamination Assembly and Hot Press

Impact by hailstone, volcanic rock, bird strike, or also dropping tools can cause damage to aircraft materials. For maximum safety, the goal is to increase Charpy impact strength (auc) of a carbon-fiber-reinforced thermoplastic polyphenylene sulfide polymer (CFRTP-PPS) composite for potential application to commercial aircraft parts. The layup was three cross-weave CF plies alternating between four PPS plies, [PPS-CF-PPS-CF-PPS-CF-PPS], designated [PPS]4[CF]3. To strengthen, a new process for CFRP-PPS was employed applying homogeneous low voltage electron beam irradiation (HLEBI) to both sides of PPS plies prior to lamination assembly with untreated CF, followed by hot press under 4.0 MPa at 573 K for 8 min. Experimental results showed a 5 kGy HLEBI dose was at or near optimum, increasing auc at each accumulative probability, Pf. Optical microscopy of 5 kGy sample showed a reduction in main crack width with significantly reduced CF separation and pull-out; while, scanning electron microscopy (SEM) and electron dispersive X-ray (EDS) mapping showed PPS adhering to CF. Electron spin resonance (ESR) of a 5 kGy sample indicated lengthening of PPS chains as evidenced by a reduction in dangling bond peak. It Is assumed that 5 kGy HLEBI creates strong bonds at the interface while strengthening the PPS bulk. A model is proposed to illustrate the possible strengthening mechanism.

Automatically controlled laser-based welding process for repair of CFRP parts

Due to a high strength-to-weight ratio, carbon fiber-reinforced plastics (CFRPs) have become a standard in the lightweight industry, which results in the development of new machining and repairing methods. Specifically, CFRP with a thermoplastic matrix material is more attractive for many applications as a thermosetting matrix material. Thermoplastic matrix materials enable new joining processes due to their thermoformability and weldability. Currently, the repair process is mainly executed manually. In order to reduce repair costs, an automated, reliable, and fast process is needed. For the new laser-based repair process, first a scarf joint is prepared in a CFRP laminate consisting of a thermoplastic polyphenylene sulfide matrix material. To refill the scarf, a patch with the same matrix material and fiber setup as the original laminate is cut into shape and welded into the scarf area. In order to obtain a reliable and stable welding process resulting in high weld seam qualities, an automated controlled welding process is being used, which controls the laser power via the surface temperature, which is detected by a pyrometer. For the development of the welding process, the influence of the welding time and the surface temperature on the resulting weld seam quality were evaluated. For the analysis of the joining quality, overlap samples were welded and tested in order to determine the weld seam strength. In addition, cross sections were prepared and analyzed with a microscope. Finally, the measured results were correlated in order to determine a parameter set generating a high-quality weld seam.

Delamination migration in CFRP laminates under mode I loading

Abstract This paper focuses on the effect of interfacial fibre orientation and interleaved veil on the delamination migration of carbon fibre reinforced polymer laminates under Mode I loading. Double cantilever beam specimens with midplane interfacial fibre orientations of 0/0, 90/90, 0/90, 0/45 and 90/45 were tested under two conditions: one with interleaved thermoplastic polyphenylene sulfide veil at the midplane and one without. Results show that, except for the 0/0 configuration, all other orientations exhibit varying levels of migration associated with the interfacial fibre orientation and veil interleaving. The apparent fracture toughness determined with the modified compliance calibration method is closely related to the delamination migration and hence a structural energy dissipation measure dependent on interfacial fibre orientation and the interleaved veil. Distributions of the fibre and matrix materials around the delamination front are found to be closely related to the delamination migration behaviour along its path. The experimental observation and rationalisation presented in this paper provide further knowledge regarding delamination migration and its correlation to the apparent fracture toughness, which is of direct relevance to the damage tolerance design of laminated composite components.

Palladium-catalyzed carbon-sulfur or carbon-phosphorus bond metathesis by reversible arylation.

Compounds bearing aryl-sulfur and aryl-phosphorus bonds have found numerous applications in drug development, organic materials, polymer science, and homogeneous catalysis. We describe palladium-catalyzed metathesis reactions of both compound classes, each of which proceeds through a reversible arylation manifold. The synthetic power and immediate utility of this approach are demonstrated in several applications that would be challenging to achieve by means of traditional cross-coupling methods. The C(sp2)-S bond metathesis protocol was used in the depolymerization of a commercial thermoplastic polymer and in the late-stage derivatization of a drug. The C(sp2)-P variant led to the convenient preparation of a variety of phosphorus heterocycles, including a potential chiral ligand and fluorescent organic materials, via a ring-closing transformation.

Effects of UV Light on Mechanical Properties of Carbon Fiber Reinforced PPS Thermoplastic Composites

SummaryThe recent attention in the applications of the fiber reinforced thermoplastic composite have raised some concerns because of the ability and performance of the fiber reinforced thermoplastic composite after long‐term exposures to environmental weathering (e.g., UV radiation, moisture, and oxygen). This weathering can be very destructive to the thermoplastic polymers; hence, a systematic study of the UV radiation effects on the properties of fiber‐reinforced thermoplastic composite is crucial for industrial applications. The major objective of the project was to study the correlation between thermoplastic fabrication parameters and the final properties of composites. In this study, carbon fiber (CF) reinforced polyphenylene sulfide (PPS) thermoplastic composites were manufactured using high temperature press after optimizing the parameters. Subsequently, the effects of long‐term UV exposures on the thermal and mechanical properties of CF/PPS thermoplastic composites were investigated in detail. The test results showed that the correlation between the processing parameters and the physical properties of the laminate composites were in all good agreements. The test results also revealed a significant decrease in the glass transition temperature, as well as storage modulus, and tensile strengths. Furthermore, short (200 hrs) and long (300 hrs) term UV exposures changed various thermal and mechanical properties of the thermoplastic PPS composites. This study can provide some preliminary knowledge to engineers and scientists in the field and develop new set of structural composites.

T-Ray NDE Inspections on the Fiber Direction of Thermoplastic PPS-Based CFRP Composites

Terahertz ray (T-ray) imaging has been emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques, and new application systems are under processing development for the area applications. The terahertz time domain spectroscopy (THz TDS) can be considered as a useful tool using general non-conducting materials; however it is quite limited to conducting materials. In this study, a new time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configuration using the terahertz time domain spectroscopy. However, the T-ray is limited in order to penetrate a conducting material to some degree. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS (poly-phenylene sulfide)-based CFRP solid laminate.

Characterization of Fiber Direction Influence in CFRP Composites Using Advanced NDE Techniques

A nondestructive technique would be very useful. Advanced NDE T-ray (terahertz ray) techniques of technology and instrumentation has provided a probing field on the electromagnetic spectrum. However, the T-ray is limited in order to penetrate a conducting material to some degree. Here, the T-ray would not go through easily the CFRP composite laminates since carbon fibers are electrically conducting while the epoxy matrix is not. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS(poly-phenylene sulfide)-based CFRP solid laminate. It is found that the electrical conductivity of CFRP composites depends on the direction of unidirectional fibers.

Use of Inorganic Fullerene-like WS2 to Produce New High-Performance Polyphenylene Sulfide Nanocomposites: Role of the Nanoparticle Concentration

The use of tungsten disulfide (WS2) nanoparticles offers the opportunity to produce novel and advanced polymer-based nanocomposite materials via melt blending. The developed materials, based on the high-performance engineering thermoplastic polyphenylene sulfide (PPS), display a unique nanostructure on variation of the nanoparticle concentration, as confirmed by time-resolved synchrotron X-ray diffraction. The cold-crystallization kinetics and morphology of PPS chains under confined conditions in the nanocomposite, as determined by differential scanning calorimetry (DSC) and atomic force microscopy (AFM), also manifest a dependence on the IF-WS2 concentration which are unexpected for polymer nanocomposites. The addition of IF-WS2 with concentrations greater than or equal to 0.5 wt % of IF-WS2 remarkably improves the mechanical performance of PPS with an increase in the storage modulus of 40-75%.

Self‐lubricating and self‐protecting properties of polymer composites for wear and friction applications

AbstractBased on the well‐known pin‐on‐disc test rig, a new test setup has been developed for online measuring of the wear and friction behavior of polymer matrix composites. Contrasting with a traditional friction and wear test rig, a steel pin and composite disc are presently used to study the influence of wear debris and fiber orientation. This test setup has a main influence on the results. The polymer materials, a thermoset polyester, and a thermoplastic polyphenylene sulfide were reinforced with glass and carbon fibers, respectively. The results show two different promising aspects of “new” materials for wear and friction applications and more specific to different machine components, namely self‐lubricating and self‐protecting ability. The self‐lubricating ability exists from creating a polymer film on the surface which reduces the coefficient of friction, and the self‐protecting behavior is because of the creation of a protecting carbon film on the surface. The self‐lubricating ability depends on the test parameters, while the self‐protecting ability was due to the material and the structure. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Facile Single-step Technique for Simultaneous In Situ Fabrication of Ag/Ag2S–Polymer Nanocomposites via PPS Cyclization Route

Abstract We herein propose a facile single-step approach involving solid-state reaction between silver salt and engineering thermoplastic polyphenylene sulfide for simultaneous in situ generation of nanoscale metallic silver as well as semiconducting silver sulfide.

The plasma treatment of thermoplastic fibre composites for adhesive bonding

The adhesive bonding of three unidirectional carbon fibre composites — with thermoplastic polyetheretherketone, thermoplastic polyphenylene sulfide and, for comparative purposes, thermosetting epoxy matrices — has been examined. The adhesives were a room-temperature-curing epoxy paste and a hot-curing epoxy film; composite substrates were pretreated by light abrasion and solvent cleaning, followed by either an oxygen-plasma or corona treatment. It is shown that good adhesive bonding of the thermoplastic composites can be achieved if a plasma treatment is used prior to bonding. For the oxygen-plasma and corona treatments employed, the adhesive fracture energy, G c , for the thermoplastic composite joints increases steadily with the intensity of the treatment until a plateau value of G c is reached. On the other hand, the thermosetting-based composite needs only light abrasion and solvent cleaning to give high values of G c . Without the oxygen-plasma or corona treatment, the thermoplastic composite joints fail at the adhesive/composite interface at a very low applied load. The oxygen-plasma and corona treatments lead to an increase in the surface concentration of polar, oxygen-containing groups, resulting in both increased wetting by the epoxy adhesive on the substrate and greater intrinsic adhesion across the adhesive/composite interface. The enhancement in intrinsic adhesion is reflected in the locus of failure of the joints moving away from the adhesive/composite interface, and in far higher values of G c .

Impact Resistance of Cross-Plied Polyphenylene Sulfide Composites

Impact resistance and residual strength of thermoplastic polyphenylene sulfide (PPS) composites are studied with regard to laminate configurations consisting of cross-plied Glass/PPS, 50% hybrid Glass/Graphite/PPS and Graphite/PPS. By means of impact testing, ballistic limit measurements show that hybridization can be used to modify penetration resistance. Residual strength measurements show that the percent reduction in strength is about 50% for all the laminate configurations The original strength values are Glass/PPS-440 MPa (63 ksi), 50% hybrid Glass/Graphite/PPS-530 MPa (76 ksi), and Graphite/PPS-585 MPa (84 ksi). For microstructural comparison of the damage modes and progression, two series of impact tests were done In one series, impact was inhibited such that only damage initiation was possible, and in the second series, the impact was allowed to a completion. Three impact velocities, 10 m/sec, 20 m/sec, and 30 m/sec were used. Microstructural observation of damage initiation alone revealed matrix cracking in Glass/PPS, delamination in Glass/Graphite/PPS, and spalling of Graphite/PPS. Further, upon completion of impact, Glass/PPS is minimally perforated and exhibits matrix crack ing and delamination, Glass/Graphite/PPS is delaminated and matrix cracking has oc curred and there is shear cut-out, and Graphite/PPS is severely sheared and forms a plug. Thus, by evaluating the microstructure after damage initiation and completion, the damage development and progression for each configuration is described.