Polyphenylene Sulfide Research Articles

Predictive Thermal Modeling and Characterization of Ultrasonic Consolidation Process for Thermoplastic Composites

Abstract Ultrasonic consolidation (USC) of thermoplastic composites is a highly attractive and promising method to manufacture high-performance composites. This work focuses on USC of dry carbon fiber (CF) fabrics with high-temperature polyphenylene sulfide (PPS) films. Experimental trials to assess feasibility of the process are time-consuming. Consequently, a predictive thermal model would facilitate process parameters selection to reduce expensive trial-and-error approaches. This paper presents a 2D finite element model of samples under consolidation, incorporating equations for viscoelastic heating, matrix phase change, and material properties. Theoretical temperature profiles for nodes of interest were compared to the corresponding experimental temperature curves for various control parameters (i.e., weld time and vertical displacement of sonotrode) and showed good agreement during heating phase. It was found that welding time values below 1750 ms were insufficient to reach melting temperature, whereas weld times above 3000 ms led to the lowest average void content (2.43 ± 0.81%). More specifically, the time the material spent above melting temperature, i.e., residence time, was established as a parameter that could estimate cases resulting in better consolidation and lower void content (time above 2600 ms for void content below 2.5%). X-ray diffraction (XRD) characterization revealed that the USC process led to mostly amorphous PPS, due to the high cooling rates (70 °C/s to 108 °C/s). Overall, the thermal model and micro-structural outcomes confirmed the feasibility of the USC process for layered composites made from dry fabric and high-temperature thermoplastic films.

Tribological properties of cyclic phenylene sulfide heat‐treated carbon fiber/polyphenylene sulfide composites

AbstractHigh‐performance self‐lubricating polyphenylene sulfide (PPS)/carbon fiber (CF) composites were obtained by treating the CF surface with heat‐treated cyclic phenylene sulfide oligomers (CPS). The influence of CPS treat conditions on the structure and properties such as mechanical and tribological performance of the composites were studied in detail. The results indicate that the PPS/CPS‐sized CF composites exhibit higher mechanical strength and better tribological performance than the PPS/original CF composites, especially under the condition of higher loads and speeds (300 N × 200 rpm and 200 N × 200 rpm). The performance enhancement is reasonably ascribed to the improved compatibility of the modified CF with the PPS matrix. Further structural analysis reveals that the modified CF treated at 300°C under N2(CF‐300N) has the most similar structure to the PPS matrix, which makes the comprehensive performances of PPS/CF‐300N composites superior to the products obtained under the other heat‐treatment conditions.

Double-Layer MWCNTs@HPPS Photothermal Paper for Water Purification with Strong Acid-Alkali Corrosion Resistance.

Solar-driven interfacial evaporation technology has been identified as a promising method to relieve the global water crisis, and it is particularly important to design an ideal structure of the solar thermal conversion evaporation device. In this paper, hydrophilic polyphenylene sulfide (HPPS) paper with loose structure and appropriate water transmission performance was designed as the based-material, and multi-walled carbon nanotubes (MWCNTs) layer with excellent photothermal conversion performance was constructed to realize the high-efficiency solar-driven evaporation. Under tail swabbing mode, the cold evaporation surface on the back of the evaporator greatly improved the evaporation rate, cut off the heat transfer channel to bulk water, and achieved the maximum evaporation rate of 1.23 L/m2·h. Ethyl cellulose (EC) was introduced to adjust the water supply performance of HPPS layer, and a large specific surface area of cold evaporation was obtained, thus improving the water evaporation rate. In the simulation experiment of seawater desalination and dye wastewater treatment, it showed good water purification capacity and acid/alkali-resistance, which had great practical application significance.

Design of sandwich-structured para-aramid paper with polyphenylene sulfide non-woven fabric for enhancing mechanical properties and breakdown strength

The rapid development of national defense, military industry, and aerospace puts forward higher requirements to the mechanical property, breakdown strength, dielectric properties, and heat resistance of high-performance aramid paper. However, the vast majority of aramid paper-based materials can hardly have a combination of satisfactory high mechanical properties and breakdown strength due to the porous structure of paper-based materials. Herein, we report a para-aramid chopped fibers/polyphenylene sulfide (ACFs/PPS) composite paper with a sandwich structure by designing the structure of aramid paper. Dense PPS microfiber membrane as robust armor filled and repaired the voids and defects on ACFs/PPS composite paper. Additionally, strong barrier interfaces between PPS film and ACFs/PPS composite paper effectively slow down the transmission of voltage to the inside of the composite paper. Thus we obtain the sandwich-structured ACFs/PPS composite paper with excellent mechanical strength (158.7 MPa) and breakdown strength (55 kV/mm), which are almost 1.5 and 2.5 times higher than ACFs/PPS composite paper, respectively. Besides, excellent mechanical properties and breakdown strength are wonderfully integrated with superior dielectric properties (tanδ <0.0035), chemical stability, and thermal stability (DTGmax > 575 °C), far superior to reported aramid paper-based materials. This work plays an important role in fabricating fabulous multi-attribute combinations of aramid paper-based materials and can also be extended to other materials and structures.

Strategies to improve joint strength of friction lap welded AA7475/PPS hybrid joint with surface pre-treatment on AA7475

Friction lap welding (FLW) technology has recently emerged as a promising joining technology to join aluminium alloys and polymers. The strength of the metal-polymer hybrid joint can be enhanced by surface pre-treating of the metal. In this study, FLW experiments were performed on the surface pre-treated aluminium alloy 7475-T761 (AA7475-T761) with Polyphenylene sulfide (PPS) polymer. Three different kinds of laser texturing patterns were made, includes grooves, circles, and square grid patterns. In addition, the alloy surface is also roughened with the wet grinding process. Surface roughness, surface topography characteristics, and contact angle (CA) were measured for treated surfaces. Furthermore, the tensile lap shear strength (TLS) of surface pre-treated FLWed joints was compared to that of untreated weldments. Results showed that the wet grinding process had minimal effect on joint strength. TLS was enhanced by 120% on a laser-textured square grid-patterned substrate in comparison with the untreated specimen weldment. The X-ray photoelectron spectroscopy (XPS) examination confirmed that the AlOC chemical bond represents the secondary bonding mechanism along the micro-mechanical interlocking.

Performance of proton exchange membrane fuel cells with microporous layer hydrophobized by polyphenylene sulfide at conventional temperature and cold start

Polyphenylene sulfide (PPS), a thermoplastic polymer with excellent chemical and thermal stability, has properties similar to those of polytetrafluoroethylene (PTFE) but is less expensive. In this study, the feasibility of using PPS to replace conventional PTFE as a hydrophobic agent for microporous layers (MPLs) in proton exchange membrane fuel cells (PEMFCs) is explored. First, PTFE-MPL and PPS-MPL with 30 wt% hydrophobic agent were prepared. The pore size, porosity, contact angle, and microstructure of the two MPL samples were measured and analyzed. Subsequently, PEMFCs with the two MPL samples were tested for their operational performance at a conventional temperature of 70 °C and cold-start capability at −10 °C. The performances of PTFE-MPL and PPS-MPL at conventional temperatures were similar, but PPS-MPL showed obvious advantages in cold-start performance. In addition, the operating performance of PEMFC at the conventional temperature and cold-start capability at −10 °C were investigated for PPS mass fractions of 10%, 20%, and 30% in MPL, and for PPS particle sizes of 10 and 30 μm. The results indicate that the optimal performance can be attained when the PPS particle size is 10 μm and the mass fraction is 20%.

Effect of Polymer Substrate on Adhesion of Electroless Plating in Irradiation-Based Direct Immobilization of Pd Nanoparticles Catalyst.

Pd nanoparticles were directly immobilized on acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), polystyrene (PS), polyphenylene sulfide (PPS), poly(vinyl chloride) (PVC), polypropylene (PP), and polyethylene (PE) polymer substrates via chemical reactions induced by ionizing irradiation. X-ray photoelectron spectroscopy analysis revealed that the chemical state of the immobilized Pd nanoparticles depended on the polymer substrate type. Electroless plating was performed using the immobilized Pd nanoparticles as the catalyst, and Cu-plating films were deposited on all polymer substrates. The results of the tape-peeling test suggested that the chemical state of the immobilized Pd nanoparticles on the polymer substrates affected the plating adhesion strength. Notably, ABS with immobilized Pd particles exhibited a high adhesion strength beyond the practical level, even without prior chemical etching. It was presumed that the high adhesion strength was owing to the anchoring effect of the holes generated on the ABS surface by ionizing irradiation.

Applicability assessment of thermoset coating onto additively manufactured thermoplastic composite molds

Coatings can significantly enhance the surface characteristics of printed molds however, there is no guideline to assess the coating applicability for additively manufactured fiber-reinforced thermoplastic molds. Therefore, the applicability of a thermoset polymer surface coating onto additively manufactured carbon fiber-reinforced Polyphenylene Sulfide (CF-PPS) composite mold was investigated. The coating application temperature should not be higher than the maximum operable temperature of the substrate. Therefore, Dynamic Mechanical Analysis (DMA) of the printed CF-PPS was performed to characterize the dependence of the elastic modulus on temperature as well as to verify the thermal stability of the printed molds at the coating processing temperature. The cure kinetics of the coating material was characterized to guide the design of processing conditions to achieve a complete cure of the thermoset resin. The composite mold needs to withstand multiple thermal cycles for the part manufacturing process. Thermal degradation of the coating was assessed for multiple thermal cycles utilizing Thermogravimetric Analysis (TGA) and the results did not show significant degradation. To provide insights into the coefficient of thermal expansion (CTE) mismatch between the coating and the printed CF-PPS, the CTE was characterized for both material systems. Additionally, the coating adhesion was characterized via pull-off tests after multiple thermal cycles and the results revealed no significant change in the pull-off strength after ten cycles. Finally, the coating was demonstrated on a mold printed with CF-PPS which was subjected to multiple autoclave composite part manufacturing cycles. The durability of the coating and the geometrical deviation of the mold were investigated throughout the manufacturing cycles.

Molecular evolution mechanism of flow-induced crystallization in polyphenylene sulfide

Microstructures play a significant role on the mechanical performance of materials. Based on the experimental characterization and molecular modeling techniques, this work assessed the influences on the mechanical properties of semi-crystalline 1-4 polyphenylene sulfide (PPS) from pressure and temperature. It was found that the shear deformation in the flow field is a key factor that induces the transformation from amorphous polymers to precursors. Though, pressure can accelerate the transition of precursors to crystals, proportion of precursors in the PPS is not observed under higher pressure. The understanding established in this work is helpful to identify optimal processing parameters during the manufacturing of PPS for target applications.

Efficient heavy metal recycling and water reuse from industrial wastewater using new reusable and inexpensive polyphenylene sulfide derivatives

Heavy metal (HM) pollution is a serious environment problem. Recovering HM from industrial wastewater by efficient adsorbents is a sustainable method due to recycling HM and acquiring reusable water. However, popular efficient adsorbents are usually expensive or non-reusable. In this paper, methods of efficient HM recycling and water reuse from industrial wastewater were developed using efficient adsorbents, new polyphenylene sulfide derivatives, which are recyclable and stable in an acidic, alkaline or oxidative aqueous solution. Moreover, they can efficiently and quickly adsorb HM ions. The maximum adsorption capacities of these adsorbents for HM ions are at the range from 51.3–184.2 mg·g−1. The adsorption equilibrium times of them for HM ions are at the range from 10 to 80 min. Therefore, this paper suggests sustainable methods of HM recovery and water reuse from industrial wastewater.

Superhydrophobic polyphenylene sulfide fiber paper with nanofiber network-like structure prepared via regulation of TIPS process for oil/water separation

Superhydrophobic polyphenylene sulfide fiber paper with nanofiber network-like structure prepared via regulation of TIPS process for oil/water separation

A water-soluble PAAs sizing agent for enhancing interfacial adhesion of carbon fiber reinforced polyphenylene sulfide composites (CF/PPS)

Due to low activity and poor wettability of carbon fiber (CF), the interaction between CF and polyphenylene sulfide (PPS) matrix is weak, which decreases the mechanical properties of CF reinforced PPS （CF/PPS） composites. In this article, the interfacial adhesion of CF/PPS composites was strengthened by using a water-soluble poly (amic acid) ammonium salt (PAAs) as sizing agent. This PAAs-based sizing agent had good compatibility with PPS and formed hydrogen bonds with CF activated by Meldrum’s acid. Significantly, the PAAs sizing agent can be soluble in water (up to 20 wt % high solid content) without organic solvents and surfactants, which shows huge potential in industrial applications. Experimental results demonstrated that the interlaminar shear strength (ILSS), flexural strengths, and moduli of modified CF/PPS composites increased by 19.5%, 24.9%, and 10.1%, respectively. According to the SEM images on fractured surfaces of composites, fiber and PPS resin were tightly packed, and the failure mechanism was interface deformation or resin breakage.

Impact of Pin Length on Joint Strength of Friction Lap Welded Aluminum Alloy 7475 and Polyphenylene Sulfide Thermoplastic Polymer Joints

Impact of Pin Length on Joint Strength of Friction Lap Welded Aluminum Alloy 7475 and Polyphenylene Sulfide Thermoplastic Polymer Joints

Effect of Polyphenylene Sulphide Particles and Films on the Properties of Polyphenylene Sulphide Composites.

Glass fibre-reinforced polyphenylene sulphide composites were prepared by hot-pressing glass fibre fabrics and polyphenylene sulphide resins. The effects of different polyphenylene sulphide resin forms on the properties of the composites were investigated using scanning electron microscopy, dynamic mechanical analyser, pendulum impact tester and universal testing machine. The results showed that different polyphenylene sulphide resin forms had nearly no effect on the glass transition temperature of the composites, which are all located at about 100 °C. Compared with other polyphenylene sulphide composites, the bending strength of polyphenylene sulphide film composites was the highest, reaching 314.58 MPa, and the impact strength of polyphenylene sulphide particle composites was the highest, reaching 245.4 KJ/m2. The bending strength and impact strength were calculated using a standard fraction, and the highest standard fraction was obtained when the ratio of polyphenylene sulphide film to particle was 1:2. The impact strength and bending strength could be obtained. The impact strength reached 229.8 KJ/m2, and the bending strength reached 284.16 MPa.

OPPS Fibers with High Temperature Resistance and Excellent Antioxidant Properties by an Oxidation Method.

Polyphenylene sulfide (PPS) fiber products have been widely used for separation and filtration in harsh environments due to their excellent chemical resistance and relatively economical price. However, the poor temperature and weak oxidation resistance of PPS significantly shorten its service life under high temperature and strong oxidation environments. Herein, we report a type of oxidation-modified PPS (OPPS) fibers with excellent high temperature and oxidation resistance. This is achieved by oxidizing the thioether sulfide groups in PPS molecular chains into sulfoxide and sulfone groups and cross-linking the intermolecular chains. Both experiments and density functional theory (DFT) calculations indicate that hypochlorous acid (HClO) molecules can rapidly oxidize the PPS fiber surface. In addition, molecular dynamics (MD) simulations prove that there are strong hydrogen bonds and van der Waals interactions between HClO molecules and OPPS molecular chains, which promote the penetration of HClO molecules into the interior of the fiber to complete the layer-by-layer oxidation. The prepared OPPS-20 fibers exhibit excellent structural stability under high temperature and strong oxidant environments. Impressively, the OPPS-20 nonwoven filter still exhibits a high dust filtration efficiency of 99.95% after aging at 320 °C for 12 h, and the corresponding pressure drop is 24 Pa. In addition, the OPPS-20 nonwoven filter also maintains excellent filtration performance after aging in 60% HNO3 solution for 12 h, and the filtration efficiency and pressure drop are 99.96% and 29 Pa, respectively. This work demonstrates that the novel OPPS fibers have excellent application prospects in the field of separation and filtration in harsh environments.

Effect of Perfluoropolymers on the Anti-Wear Properties of Carbon Fiber/Polyphenylene Sulfide Composites: A Comparative Study

In this work, several perfluoropolymers (PFP), including commercial polytetrafluoroethylene (PTFE), perfluorinated ethylene-propylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and irradiated PTFE (iPTFE) were used as additives to lubricate carbon fiber (CF)-reinforced polyphenylene sulfide (PPS) composites. The tribological properties of the yielding composites were studied and correlated with the melt processability of PFPs. Although the neat FEP and PFA have higher friction coefficients when compared with neat PTFE, the composites filled with FEP and PFA additives were found to exhibit a lower friction coefficient compared to PTFE at PFP content below 10 wt %. Moreover, the iPTFE-filled composites also showed similar results as FEP or PFA filled ones, very different from PTFE at low additions. Based on the morphological investigation, we postulate that FEP, PFA, and iPTFE are melt-kneaded with PPS due to their melt processability at processing temperature, leading to the good dispersion in composites in the form of smaller deformed spheres and/or fibril bands. The well-dispersion of PFPs in composites promotes the formation and growth of the transfer film on the counterface during sliding.

Biological oyster shell waste enhances polyphenylene sulfide composites and endows them with antibacterial properties

To date, there is no research that deals with biological waste as fillers in polyphenylene sulfide (PPS). In this study, oyster shells were recycled and treated to prepare thermally-treated oyster shells (TOS), which were used as PPS fillers to make new bio-based antibacterial composite materials. The effect of varying the content of TOS was studied by means of structure and performance characterization. PPS/TOS composites were demonstrated to have an antibacterial effect on the growth of E coli and S. aureus. Qualitative analysis showed that when the TOS content was ≥ 30% and 40%, the composite materials had an apparent inhibition zone. Quantitative analysis showed that the antibacterial activity increased with the TOS content. Fourier transform infrared spectroscopy indicated the formation of hydrogen bonds between the molecular chains of TOS and PPS and the occurrence of a coordination reaction. At 10% TOS, the composite tensile strength reached a maximum value of 72.5 MPa, which is 9.65% higher than that of pure PPS. The trend of bending properties is the same as that of tensile properties, showing that the maximum property was reached for the composite with 10% TOS. At the same time, the crystallinity and contact angle were the highest, and the permeability coefficient was the lowest. The fatigue test results indicated that for the composite with 10% TOS, the tensile strength was 23% lower than static tensile strength, and the yield strength was 10% lower than the static yield strength. The results of the study showed that TOS not only could reduce the cost of PPS, but also could impart antibacterial properties and enhance the mechanical and, barrier properties, the thermostability, as well as the crystallinity.

Competition of memory effect and thermal degradation on the crystallization behavior of polyphenylene sulfide

Polyphenylene sulfide (PPS) is one of most widely used special engineering plastics in the world. However, owing to the unique memory effect and thermal degradation effect, the crystalline structure of PPS is extremely difficult to control during the practical processing, resulting in the deterioration of processability and performance of PPS products. In this work, the differential scanning calorimetry (DSC), polarized optical microscopy (POM), in-situ X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and rheological tests were carried out to distinguish these two effects on the crystallization behavior of PPS systematically. It is found that the memory effect and thermal degradation compete “as one falls, another rises” on the crystallization behavior of PPS, both of which accelerate the crystallization rate and reduce the uniformity of crystalline structure. The residual of local ordered structures in PPS melt increases the nucleation rate significantly and could be eliminated as the pre-treatment temperature (Tp) reaches 350 °C. Nevertheless, the chain scission reaction is activated and dominates the crystallization process of PPS when Tp is higher than 350 °C, leading to the notable promotion of crystal growth rate. Accordingly, processing around the transition temperature can minimize the cooperation of melt memory and thermal degradation on the crystallization behavior of PPS, resulting in the lowest crystallization rate and the most uniform crystal size distribution.

Polyphenylene Sulfide Ultrafine Viscous Fibrous Membrane Modified by ZIF-8 for Highly Effective Oil/Water Separation under High Salt or Alkaline Conditions.

The oil/water separation in harsh environments has always been a challenging topic all over the world. In this study, the ZIF-8/PPS fiber membranes were fabricated via the combination of hot pressing and in situ growth. The distribution of ZIF-8 in the membranes was adjusted by changing the ZIF-8 in situ growth time, which could control the oil/water separation effect. Due to the hydrophilic nature of the ZIF-8/PPS fiber membranes, the water molecules in the oil-in-water emulsion could quickly penetrate into the fiber membrane under the drive of pressure, gravity, and capillary force, forming a water layer on the surface of the fiber membranes. The coupling of the water layer and the fiber structure prevented direct contact between the oil molecules and the fiber membrane, thereby realizing the separation of the emulsion. The results show that when the ZIF-8 in situ growth time was 10 h, the contact angle, the porosity, and the pure water flux of the ZIF-8/PPS fiber membranes were 72.5°, 52.3%, and 12,351 L/h·m2, respectively. More importantly, the separation efficiency of M10 was 97%, and the oil/water separation efficiency reached 95% after 14 cycles. This study provides a novel strategy for preparing MOFs/fiber materials for oil/water separation in harsh environments.

Cooling rate-dependent mechanical properties of polyphenylene sulfide (PPS) and carbon fiber reinforced PPS (CF/PPS)

This study investigated the effect of cooling rates on the crystallization, thermomechanical, and fracture properties in both semi-crystalline thermoplastic resin (polyphenylene sulfide, PPS) and carbon fiber reinforced PPS (CF/PPS). Our results showed that high crystallinity caused by a slow cooling rate increases the elastic modulus and yield stress but decreases the strength and fracture toughness. This trend is caused by the competing influences between high stiffness of the crystal layer and high ductility of the amorphous layer. Particularly, in neat resin, a transition from brittle to ductile fractures emerged between 1 and 10 °C/min and highly increased the fracture toughness. However, because of the weak bonding between the fiber and PPS, the fracture toughness of CF/PPS was less affected by the cooling rate and was significantly lower than that of neat PPS. This means that the fiber/matrix interface properties are the key factors affecting the mechanical properties of CF/PPS.