Pure PPS Research Articles

Effect of Carbon Nanofibers (CNF) on The Crystallization Kinetics of Polyphenylene Sulfide (PPS)

The presence of a reinforcement in polymeric materials can cause alterations in their physical properties, and increase the crystallization rate of their polymeric matrix. Therefore, this research work was oriented toward the incorporation of different percentages of carbon nanofibers (0.6-1-3 and 5%) in a PPS thermoplastic matrix, with the purpose to establish and understand each one of the variables that control crystallization kinetics. The results showed a gradual decrease in crystallization times for contents of up to 5% of CNF, where carbon nanofibers act as nucleation sites, accelerating the crystallization process. According to the values obtained in the Avrami exponent, these fell within a range that oscillates from 2.5 to 3 for pure PPS and PPS/1%CNF which indicates that the presence of carbon nanofibers does not have an effect on the nucleation mechanism of polyphenylene sulphide crystalline phase, thus suggesting crystallization with heterogeneous nucleation and two-dimensional growth with circular geometry

A Cleanable Self-Assembled Nano-SiO2/(PTFE/PEI)n/PPS Composite Filter Medium for High-Efficiency Fine Particulate Filtration.

A silicon dioxide/polytetrafluoroethylene/polyethyleneimine/polyphenylene sulfide (SiO2/PTFE/PEI/PPS) composite filter medium with three-dimensional network structures was fabricated by using PPS nonwoven as the substrate which was widely employed as a cleanable filter medium. The PTFE/PEI bilayers were firstly coated on the surfaces of the PPS fibers through the layer-by-layer self-assembly technique ten times, followed by the deposition of SiO2 nanoparticles, yielding the SiO2/(PTFE/PEI)10/PPS composite material. The contents of the PTFE component were easily controlled by adjusting the number of self-assembled PTFE/PEI bilayers. As compared with the pure PPS nonwoven, the obtained SiO2/(PTFE/PEI)10/PPS composite material exhibits better mechanical properties and enhanced wear, oxidation and heat resistance. When employed as a filter material, the SiO2/(PTFE/PEI)10/PPS composite filter medium exhibited excellent filtration performance for fine particulate. The PM2.5 (particulate matter less than 2.5 μm) filtration efficiency reached up to 99.55%. The superior filtration efficiency possessed by the SiO2/(PTFE/PEI)10/PPS composite filter medium was due to the uniformly modified PTFE layers, which played a dual role in fine particulate filtration. On the one hand, the PTFE layers not only increase the specific surface area and pore volume of the composite filter material but also narrow the spaces between the fibers, which were conducive to forming the dust cake quickly, resulting in intercepting the fine particles more efficiently than the pure PPS filter medium. On the other hand, the PTFE layers have low surface energy, which is in favor of the detachment of dust cake during pulse-jet cleaning, showing superior reusability. Thanks to the three-dimensional network structures of the SiO2/(PTFE/PEI)10/PPS composite filter medium, the pressure drop during filtration was low.

Do self-reports of procrastination predict actual behavior?

ObjectivesProcrastination is typically assessed via self‐report questionnaires. So far, only very few studies have examined actual procrastination behavior, providing inconclusive results regarding the real‐life validity of self‐reports in this domain. The present study aimed to examine for the first time whether participants' self‐reported procrastination can predict their actual behavior on a real‐life task.MethodsFor that purpose, we assessed self‐reported levels of procrastination [via the Pure Procrastination Scale, PPS] and actual procrastination behavior on a naturalistic task [i.e., having to send in an attendance sheet before a deadline] in 93 participants.ResultsResults show that self‐reports significantly predicted procrastination behavior. Analyses of underlying dimensions suggest that real‐life procrastination can be the result of “voluntarily delaying planned actions,” but can also have more passive causes such as “running out of time.”ConclusionsComparing our results with the available literature suggests that PPS self‐reports reflect a particularly valid tool to assess real‐life procrastination behavior. Findings are discussed in the context of strategies and mechanisms that potential interventions may target in order to reduce procrastination.

Conductive films of silver nanoparticles as novel susceptors for induction welding of thermoplastic composites

In the present work, a conductive film of silver nanoparticles (nAg) as a novel heating element type, called susceptor, was developed and tested for induction welding of carbon fiber/polyphenylene sulfide (CF/PPS) thermoplastic composites, i.e., unidirectional pre-impregnated 16 plies of CF/PPS compression-molded in a quasi-isotropic stacking sequence. The nAg were synthesized, dispersed in deionized (DI) water and casted onto a pure PPS film, resulting in a conductive film upon the evaporation of DI water and thermal post-annealing. The thermal annealing at 250 °C significantly (by 7 orders) decreased the film’s electrical resistivity from 9.4 × 103 down to 3.1 × 10−4 Ω cm. The new susceptors led to fast heating rates in induction welding when compared to the standard stainless steel mesh susceptors under similar welding conditions. Lap shear mechanical testing revealed that the apparent lap shear strength (LSS) is sensitive to the susceptors’ resistivity and the input current. A relatively high LSS value was achieved for the specimens welded using the new susceptors which exceeded the value of those welded using stainless steel mesh susceptors (28.3 MPa compared to 20 MPa). The weld interface and specimens’ cross-section observation revealed that the nAg were dispersed and embedded into the resin upon welding. This study contains preliminary results that show high potential of nanoparticles as effective susceptors to further improve the mechanical performance of the joints in welding of thermoplastic composites.

A sturdy self-cleaning and anti-corrosion superhydrophobic coating assembled by amino silicon oil modifying potassium titanate whisker-silica particles

A sturdy self-cleaning and anticorrosion superhydrophobic coating based on poly(phenylene sulfide) (PPS) matrix has been successfully fabricated by combination of sol-gel and spraying technology without using any fluorine materials. The prepared coating possessed excellent superhydrophobicity with the water contact angle (WCA) (161 ± 1.2)° and slide angle (SA) (2 ± 1.5)°, which was ascribed to the synergistic effect of low-surface energy material amino silicon oil (ASO) and the binary potassium titanate whisker-silica (PTW-SiO2) composite particles formed by in-situ growth of SiO2 on modified PTW via sol-gel. Moreover, The PPS/ASO/PTW-SiO2 superhydrophobic coating exhibited decent self-cleaning property with clean surface even after 100 times immersion in muddy solution. The abrasion test demonstrated that the mechanical stability of prepared coating was about 2 times of the pure PPS coating. Simultaneously, the potentiodynamic polarization and electrochemical impedance spectroscopy testified the excellent corrosion resistance of prepared coating with the performance of lower corrosion current (1.289 × 10−10 A/cm2) and high protection efficiency (99.999%) even after immersion in 3.5 wt.% NaCl solution for 28 days. It is believed that this sturdy self-cleaning and anti-corrosion superhydrophobic coating might have a promising application prospect in industry.

Effect of polyphenylene sulfide containing amino unit on thermal and mechanical properties of polyphenylene sulfide/glass fiber composites

ABSTRACTThree kinds of high‐molecular‐weight compatibilizers [copoly(1,4‐phenylene sulfide)‐poly(2,5‐phenylene sulfide amine)] (PPS‐NH2) containing different proportions of amino units in the side chain) were synthesized by the reaction of dihalogenated monomer and sodium sulfide via nucleophilic substitution polymerization under high pressure. The intrinsic viscosity of the obtained copolymers was 0.354–0.489 dL/g and they were found to have good thermal performance with melting point (Tm) of 271.3–281.0 °C and initial degradation temperature (Td) of 490.0–495.7 °C. There was an excellent physical compatibility between PPS‐NH2 and the pure industrial PPS. The results of dynamic mechanical analysis and macro‐ and micromechanical test showed that the selective compatibilizer PPS‐NH2 (1.0) (1.0% mol aminated ratio) can improve the mechanical and interfacial properties of polyphenylene sulfide/glass fiber (PPS/GF) composite. The macro‐optimal tensile strength, Young's modulus, bending strength, and notched impact strength of 5%PPS‐NH2 (1.0)/PPS/GF composite raised up to 141 MPa, 1.98 GPa, 203 MPa, and 6.15 kJ/m2, which increased 12.8%, 9.4%, 4.1%, and 13.8%, respectively, comparing with the pure PPS/GF composite (125 MPa, 1.81 GPa, 195 MPa, and 5.40 kJ/m2, respectively). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45804.

C60 as fine fillers to improve poly(phenylene sulfide) electrical conductivity and mechanical property

Electrical conductive poly(phenylene sulfide) (PPS)/fullerene (C60) composites were prepared by 1-chlornaphthalene blending method, and the interface effects of C60 and PPS on PPS/C60 properties were characterized. C60 is an excellent nanofiller for PPS, and 2 wt% PPS/C60 composite displayed the optimal conductivity which achieved 1.67 × 10−2 S/cm. However, when C60 concentration reached 2 wt%, the breaking strength and tensile modulus of PPS/C60 fiber achieved maximum 290 MPa and 605 MPa, and those values were 7.72 and 11.2 times as that of pure PPS. The excellent conductive and mechanical properties of PPS/C60 were attributed to the heterogeneous nucleation of C60 during PPS crystallization, formation of a large number of covalent bond by main C60-thiol adducts and minor C60-ArCl alkylation between C60 outer surface and PPS matrix. At same time, PPS/C60 thermal properties were also investigated.

Novel Heating Elements for Induction Welding of Carbon Fiber/Polyphenylene Sulfide Thermoplastic Composites

Conductive films of carbon nanofibers (CNFs) decorated/coated with metals, either silver (Ag) or nickel (Ni) are fabricated using a solution casting process and used as novel heating elements (HEs) for induction welding of carbon fiber/polyphenylene sulfide (CF/PPS) thermoplastic composites. Prior to making the films, the metal‐coated CNFs are prepared by an electroless plating method using Ag or Ni precursors. A solution of the metal‐coated CNFs is then casted onto a pure PPS film to give a robust conductive film upon solvent evaporation and annealing in an oven at 200 °C. SEM observation and electrical resistivity measurements reveal that the CNFs are successfully coated with the metals which result in a significant decrease of the films’ electrical resistivity. A third type of HE is also fabricated by solution mixing Ag‐coated CNFs and magnetic Fe3O4 nanoparticles. The welding efficiency of the fabricated films is assessed for induction welding of two different types of thermoplastic composites, that is, unidirectional pre‐impregnated 16 plies ​​of CF/PPS compression‐molded in a quasi‐isotropic stacking sequence and 8‐ply of satin weave fabric CF/PPS compression‐molded in a cross‐ply stacking sequence. The mechanical apparent lap shear strength (LSS) of the induction‐welded joints is evaluated for the fabricated HEs and compared with the LSS of joints welded using conventional stainless steel mesh susceptors. Under similar testing conditions, Ag‐coated CNFs HEs lead to the highest LSS with an average value of ≈31.5 MPa. In general, the new HEs result in superior LSS and higher heating rates when compared to the metallic mesh counterparts. The present work offers a new perspective to push the boundaries toward high quality welding of thermoplastic composites using nanomaterials‐based HEs.

A fluorine-free superhydrophobic PPS composite coating with high thermal stability, wear resistance, corrosion resistance

Abstract A simple spraying method was used for fabricating stability and wear-resistance fluorine-free superhydrophobic coatings by introducing the silicone rubber (SR) particles and carbon nanotubes (CNTs) into poly(phenylene sulfide) (PPS) matrix. When the weight content of PPS:SR:CNTs = 0.7:0.3:0.015, the water contact angle (WCA) and the slide angle (SA) of the prepared coating were (164 ± 1.5)° and (1 ± 0.8)°, respectively. The WCA of the prepared coating also possessed good durability, which could maintain (141 ± 1)° after 10,000 times of abrasion. It was mainly ascribed to the internal micro/nano-structure designed by combining SR particles with CNTs and low surface free energy groups Si-CH3 of SR. Moreover, the prepared coating exhibited excellent wear resistance, which was 2 times higher than pure PPS coating. The adhesive ability of the prepared coating corresponded with Grade 4 according to ASTM D3359 due to the synergy of SR particles and CNTs. The test results of thermogravimetric (TG) indicated the outstanding thermal stability of the prepared coating with weight loss less than 10% under 478 °C. Furthermore, the corrosion resistance of the aluminum could be effectively enhanced by the prepared superhydrophobic coating with performance of higher corrosion potential −756.69 mV and lower corrosion current 4.97 × 10−8 A/m2 after 15 days immersion in 3.5 wt.% NaCl solution. Therefore, it is believed that the prepared coating with excellent thermal-stability, wear-resistance and corrosion-resistance might have a huge potential in large-scale industrial application.

Why Synthesizing Poly(1,4-Phenylene Sulfide) through Oxidative Polymerization Has not so far Been Adopted as the Industrial Process

Synthesis of poly (1, 4-phenylene sulfide) (PPS) through oxidative polymerization seems promising to us. Comparing with current commercial method to poly (1, 4-phenylene sulfide) from 1, 4-phenylene sulfide and sodium sulfide (Phillips’ Method), there are many advantages of the oxidative polymerization method. For example, it can synthesize PPS at normal temperature and pressure; the yield of reaction is very high; it provides pure PPS without salt contamination. However, several years have passed away; synthesis of poly (1, 4-phenylene sulfide) through oxidative polymerization has not so far been adopted as the industrial process. Many of us are puzzled, why? Through studying all kinds of reported preparation route to poly (1, 4-phenylene sulfide) through oxidative polymerization compared to Phillips’ Method, a generic polymerization mechanism is achieved for most of them excepting two with obvious shortcomings. We suddenly realize that synthesis of poly (1, 4-phenylene sulfide) through oxidative polymerization seems unsuitable to be used in industrial production recently because of its own limits.

Microcellular foams of glass-fiber reinforced poly(phenylene sulfide) composites generated using supercritical carbon dioxide

Microcellular foaming of poly(phenylene sulfide) (PPS) and its glass–fiber (GF) reinforced composites using supercritical CO2 as a blowing agent presents a promising approach to produce novel cellular materials with tailored microstructures. This study investigated the effects of the material composition and process conditions on the foaming behaviors and final morphologies of the microcellular foamed PPS and PPS/GF composites. The rheological and thermal properties as well as the saturation and desorption behaviors of CO2 in the pure PPS and PPS/GF composites were also detailedly discussed. The results show that microcellular foams with various relative densities, cell sizes, cell-size distributions, and cell densities can be attained by tailoring the fiber content and key process parameters. At low foaming temperatures below the cold crystallization temperature, the microcellular foamed PPS and PPS/GF composites both present a unimodal cell-size distribution. At elevated temperatures, the generated crystalline superstructures including spherulites in the polymer matrix and transcrystals around the GF will cause a secondary heterogeneous cell nucleation. This leads to the observations of bimodal and trimodal cell-size distributions in the pure PPS and the PPS/GF composites, respectively. The mechanisms for the solid-state foaming behaviors of pure PPS and PPS/GF composites have been illustrated by establishing theoretical models. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

A computed model for tribological properties of porous self-lubricating PPS composites: Numerical analysis and experimental verification

A novel 2D model that was based on the cross-section microstructure of porous PPS composites was established to predict its tribological properties. The variable λ, based on pore size and spacing, was used in the micro-scale model. Heat-stress coupled field analysis was applied to study the self-lubricating behavior and the effects of porosity on the tribological properties of porous PPS composites. The approach included the distributions of temperature, displacement and Von Mises stress. Experimental results indicated that the porous PPS composites exhibited a 13,000-fold increase in wear resistance and a 90% decrease in friction coefficient compared with pure PPS under dry sliding condition. The micro-scale pores of composite were filled with grease, contributing to the decrease of friction coefficient and wear rate. Simulation results revealed that the optimum porosity significantly improved the self-lubricating performance of porous PPS composites. The accuracy of numerical analysis was verified by comparing it with experimental results. The errors were less than 11%.

Study on Preparation and Property of High Thermal Oxidation Stability PPS/SiO<sub>2</sub> Fiber

PPS/SiO2 composite was studied to enhance the thermal oxidation stability of PPS. In order to improve the dispersity of SiO2 in PPS matrix, the SiO2 was modified by silane coupling agent, KH-570. The fractured surface morphologies, thermal properties and rheological property of PPS/SiO2 composite were researched. The high thermal oxidation stability PPS/SiO2 fibers were prepared by melt spinning. The thermal ageing treatment was carried out, and the strength and retention strength, before and after ageing treatment, of two kinds of fibers (PPS fibers and PPS/SiO2 fibers) were compared. The results of SEM showed the good dispersity of the modified SiO2 in PPS matrix. After adding modified SiO2, the initial decomposition temperature increased. At the same time, the fiber strength and retention strength were improved, which can be found by comparing. Compared with pure PPS, after adding 1.0 wt%, which was proved to be the optimum dosage by the research, modified SiO2 into PPS, the initial decomposition temperature was increased by 15.3°C, the retention strength was increased from 60.3% to 85.1% after ageing treat.

Thermal percolation behavior of graphene nanoplatelets/polyphenylene sulfide thermal conductivity composites

The volume fraction of functionalized graphene nanoplatelets (GNPs) influencing on the thermal conductivities of GNPs/polyphenylene sulfide (GNPs/PPS) composites are investigated. Results reveal that a great improvement of the thermal conductivities with the addition of functionalized GNPs, and the thermal conductivity of the GNPs/PPS composite is 4.414 W/mK with 29.3 vol% functionalized GNPs, 19 times higher than that of the pure PPS matrix. The significantly high improvement of the thermal conductivities is ascribed to good thermal transmission through GNPs networks in the PPS matrix, following a thermal percolation behavior. Meantime, the GNPs have strong ability to generate continuous thermally conductive chains, and the formation of thermally conductive networks becomes much easier. POLYM. COMPOS., 35:1087–1092, 2014. © 2013 Society of Plastics Engineers

Tribological properties of porous PPS/PTFE composite filled with mesopore titanium oxide whisker

Nano-micro hierarchical porous polyphenylene sulfide/polytetrafluoroethylene (PPS/PTFE) composites were prepared by mold-leaching and vacuum melting process under high temperature condition. The tribological behaviors of porous PPS/PTFE composites and the synergism as a result of incorporation of both micro-porogen (NaCl) and mesoporous TiO2 whiskers were investigated. The effects of mesoporous TiO2 whiskers and nonperforated TiO2 whiskers on the friction and wear properties of PPS/PTFE composites were comparatively studied, respectively. Results indicated that the wear rate of porous PPS/PTFE composites with 30 wt % NaCl and 7 wt % mesoporous TiO2 whiskers obtained the lowest values under the load of 100 N. Compared with pure PPS, the wear resistance of nano-micro porous PPS/PTFE composite was enhanced by 6.45 × 103 times, showing outstanding wear resistance. During sliding condition, grease could be squeezed through the nano-micro pores under the coupling effect of load and friction heat, and formed a lubricanting layer on friction surface, providing self-lubricating effect and high wear resistance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Boron Nitride Based Poly(phenylene sulfide) Composites with Enhanced Thermal Conductivity and Breakdown Strength

Dielectric polymer composites with high thermal conductivity and high breakdown strength have wide applications in electronic devices and electrical equipment. In this study, poly(phenylene sulfide) [PPS] and boron nitride (BN) were selected for preparing high thermal conductivity composites for high temperature insulation application. The composites were prepared by melt compounding to contain 0-40.0wt% BN. Laser flash method was used to measure the thermal conductivity. As a result, the composites exhibit significantly enhanced thermal conductivity when compared with the pure polymer. For instance, the composite sample shows an increase of thermal conductivity from 0.28W/(m·K) (the pure PPS) to 1.21W/(m·K) when it contains 40.0wt% BN. Weibull statistical distribution was used to analyze the breakdown data and the characteristic breakdown strength was used to compare the breakdown strength of various samples. It was found that, except the sample containing the low concentration of BN filler, the composites show enhanced breakdown strength when compared with the pure PPS. Scanning electron microcopy (SEM) results show that the BN flakes are homogeneously distributed in the PPS matrix. Thermogravimetric analysis shows that the composites have increased thermal stability when compared with the pure PPS.

Effect of Curing Poly(<i>p</i>-Phenylene Sulfide) on Thermal Properties and Crystalline Morphologies

Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C showed a monotonous increase of crystallization temperature compared to pure PPS. However, a further increase of curing time decreased the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the crystallization temperature. Thus, the cross-linking of PPS affected crystallization behaviors significantly. To a certain extent, crosslinks acted as nucleation agents, but excessive cross-linking hindered the crystallization. Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS.

Preparation of SiO<sub>2</sub>/PPS Fiber and Study of its Heat-Resistant Properties

Through the addition of nano-silicon dioxide in the pure polyphenylene sulfide, the masterbatches were obtained, then using melt spinning technology to prepare SiO2/PPS fiber. The structure and heat-resistant properties of samples were characterized by transmission election microscopy (TEM), infrared spectrum (IR), differential scanning calorimeter (DSC) and other measurements. The experiment results indicate that the mechanical and heat resistance properties of PPS fiber were improved after adding the content of 1%wt nano-silicon dioxide. When the fiber was heated at 230°C for 24 hours, the breaking strength and elongation increased by 2.412cN/dtex and 11.90% compared to the pure PPS fiber. Moreover, the working temperature raised by 50°C.

Fabrication, thermal and electrical properties of polyphenylene sulphide/copper composites

The thermal and electrical properties of high performance poly(phenylene sulphide) (PPS) composites reinforced up to 31 vol% Cu particles were investigated to be used as materials for electronic applications. The thermal stability and char yield of the composites increased significantly. Both pre- and post- glass transition coefficient of thermal expansion (CTE) of composites decreased significantly. The microhardness was increased by more than 50% compared to pure PPS matrix. Microhardness and CTE of composites correlated well with the rule of mixtures. A percolation threshold about 6 vol% Cu was obtained. The electrical conductivity was increased by about eight orders of magnitude for 18 vol% composite. Dielectric constant and dissipation factor of composites at 1 MHz was increased by about 6-fold and 70-fold compared to matrix, respectively. They decreased gradually with increasing frequency up to 1 MHz and thereafter, there was insignificant change. The scanning electron microscope showed almost uniform distribution of Cu particles in the matrix. Owing to better dimensional stability and good electrical properties, these composites are very promising for electronic applications.

Electrical properties of polymer/expanded graphite nanocomposites with low percolation

Expanded graphite (EG)-filled poly(phenylene sulfide) (PPS) nanocomposites prepared by a simple method exhibited an electrical conductivity percolation threshold of 1 wt% (0.6 vol%). In contrast to this, the percolation threshold of micrometre-sized graphite flake filled PPS composites prepared by the same method was 5 wt%. The electrical conductivity for 2 wt% nanocomposites increased 14 orders of magnitude higher than that of pure PPS. The dielectric constants and dissipation factor of nanocomposites were measured in a frequency range from 100 kHz to 15 MHz. The dielectric constant of the nanocomposites with more than 1 wt% EG showed a strong dependence on EG content and frequencies. The dielectric constants for 2 wt% and 10 wt% nanocomposites measured at 1 MHz were increased more than 102 and 105 times, respectively. Similarly, the dissipation factor was increased. Scanning electron microscopy showed a three-dimensional conducting network of EG across the PPS matrix which may be the reason for the significant improvement in electrical properties. The significantly increased electrical conductivity, dielectric constant and dissipation factor of the nanocomposites are favourable for their use in antistatic and electromagnetic interference shielding applications.