A study on the ternary blends of polyphenylenesulfide,polysulfone, and liquid crystalline polyesteramide

Ternary blends of poly(p-phenylenesulfide) (PPS), thermotropic liquid crystalline polyesteramide (LCP), and polysulfone (PSF) were investigated in terms of processing characteristics, blend morphology, and physical properties. In the incompatible PPS/LCP blends, LCP imparted a nucleating effect to the crystallization of PPS. Up to 10wt% LCP content, the tensile properties of PPS/LCP blends were enhanced with increasing LCP content, but they deteriorated if the LCP content exceeded 20wt%. Addition of a third component, PSF, to the 90/10 PPS/LCP blend promoted development of rodlike or threadlike fibrillar structure and orientation of the deformed LCP domains, which led to improvement of tensile strength up to 20%.     

Poly(p-phenylene sulphide)/liquid crystalline polymer blends. I. Miscibility and morphologic studies

The miscibility in the melt and solid state of blends made of poly(p-phenylene sulphide) (PPS) with a liquid crystalline polymer (LCP) from DuPont was studied by polarized light optical microscopy (PLOM) and dynamic thermal mechanical analysis. Both techniques showed that the PPS and the LCP are immiscible in both states, and that the critical concentration for the formation of fibrils C^*, in this particular system, was located between 20 and 25 wt % LCP. The resultant blend morphology was studied by PLOM and scanning electron microscopy (SEM). It was observed that when LCP fibrils are formed in the PPS matrix, the PPS macromolecules will crystallize around the LCP fibrils by forming columnar layers called transcrystallites. These transcrystallites are the result of the LCP acting as a nucleating agent for the PPS, promoting heterogeneous nucleation. © 1996 John Wiley & Sons, Inc.     

A preliminary investigation of flash formation during injection molding of polyphenylene sulfide and liquid crystalline polymer blends

Flashing in pure polyphenylene sulfide (PPS) and a blend containing PPS and liquid crystalline polymer (LCP) during injection molding was investigated by differential scanning calorimetry and scanning electron microscopy. The shape of the flash was observed by use of a projector. Flashing was detected in pure PPS and 90/10 PPS/LCP blend but was not found in other compositions, including pure LCP. The DSC thermograms of the flash revealed both exothermic and endothermic peaks at around 120° and 285°C. The first peak, known as crystallization temperature on heating, occurred as a result of early crystallization of PPS. The observed double peaks indicated that the degree of crystallinity was lower in the flash than in the molded part. The morphological studies revealed the presence of LCP fibrils in the skin region and droplets in the core region of 90/10 PPS blend. The absence of flash was attributed to the diameters of the fibrils and droplets, which were found to increase with increasing LCP component.     

Rheology of blends of a thermotropic liquid crystalline polymer with polyphenylene sulfide

Blends of thermotropic liquid crystalline polymer (LCP) and polyphenylene sulfide (PPS) were studied over the entire composition range using Rheometrics Stress Rheometer, capillary rheometer, and differential scanning calorimeter. There is no molecular scale mixing or chemical reaction between the components, as evidenced by melting and crystallization points in the PPS phase. From the strain scaling transients test at low‐rate, LCP and the blends require approximately 60 strain units to obtain steady stale shearing results. The large recoveries in the strain recovery test, magnitude 3 to 3.3 strain unit, are likely the results of texture present in LCPs. With increasing PPS content in LCP/PPS blends, the total recovery declines. Scaling of the transient strain rate remains, but the magnitude of the transients is reduced. At low‐rate, when the LCP is added to the PPS, the pure melts have similar visosity: 500 Pa · s for LCP and 600 Pa · s for PPS, but the viscosity of the blends goes through a maximum with concentration that is nearly three times the viscosity of the individual melts. At high‐rate, a significant depression of the viscosity is observed in the PPS‐rich compositions and this may be due to the fibrous structure of the LCP at high shear rates.     

Poly(p-phenylene sulfide)/liquid crystalline polymer blends. II. Crystallization kinetics

The crystallization kinetics of blends made of poly(p-phenylene sulfide) (PPS) with a liquid crystalline polymer (LCP) was studied. The blends were found to be immiscible by dynamic mechanical thermal analysis (DMTA). Results of non-isothermal and isothermal crystallization experiments made by differential scanning calorimetry (DSC) showed that both components had their crystallization temperatures increased; also the LCP melting temperature was found to increase in the blends. It was concluded that the addition of LCP to the PPS increased the PPS overall crystallization rate due to heterogeneous nucleation. The fold interfacial free energy, σ_e of the PPS in the blends was observed not to vary with composition. © 1996 John Wiley & Sons, Inc.     

Polymer bonded magnets. II. Effect of liquid crystal polymer and surface modification on magneto‐mechanical properties

We studied the effect of liquid crystal polymer (LCP) and surface modification of neodymium‐iron‐boron (Nd‐Fe‐B) magnetic alloy on the magneto‐mechanical behavior of poly (phenylene sulfide) (PPS) bonded Nd‐Fe‐B magnets to accelerate efforts to develop useful thermoplastic magnets with optimal performance. The results indicate that blending the LCP with PPS provides the required balance of properties for the targeted applications. These properties include superior magneto‐mechanical performance at elevated temperatures, minimal melt viscosity at optimal LCP volume fraction, high stiffness, and improved dimensional stability, making the thermoplastic magnets suitable for use at elevated temperatures and in chemically corrosive environments where commercial rare earth alloy magnets are not useable. Enhanced wetting of the magnetic Nd‐Fe‐B powders by the polymers, formation of reinforcing LCP domains, and interactions between the polymers and the magnetic powders are thought to be responsible for the beneficial function of the LCP and Nd‐Fe‐B surface modifier in the PPS bonded Nd‐Fe‐B magnets.     

Through-thickness distribution of LCP in PPS/LCP blends

Through-thickness distribution of liquid crystalline polymer (LCP) of blends containing polyphenylene sulfide (PPS) and LCP was investigated using differential scanning calorimetry and scanning electron microscopy. The effect of the LCP distribution on the mechanical test was checked through bending testing of the various compositions of the injection molded samples. These studies showed a nonuniform distribution of LCP in the PPS-rich region where the LCP content in the skin layer was higher than in the core layer or boundary between the two layers. The LCP component was uniformly distributed in the LCP-rich region. The increase of bending modulus with increasing LCP content was attributed to the reinforcing nature of the LCP fibrils in the skin layer. © 1994 John Wiley & Sons, Inc.     

国外工程塑料新品级的开发状况

叙述了国外最近对聚甲醛、聚碳酸酯、聚酯、聚苯醚、聚苯硫酸、液晶聚合物及热塑性聚酰亚胺７种工程塑料新品级及其应用的开发状况。     

Effects on the melt rheology of systems of Nd‐Fe‐B particles suspended in a poly(phenylene sulfide) and liquid crystalline polymer blend

The melt rheology of blends of a liquid crystalline polymer (LCP) and poly(phenylene sulfide) (PPS) and their composites with ferromagnetic Nd‐Fe‐B particles (MQP) was studied. We investigated the effects of LCP concentration, Nd‐Fe‐B particle volume fraction and size, distribution, and shear rate on the rheological properties of these composites. Enthalpy of fusion changes that were observed resulted from the addition of the LCP and Nd‐Fe‐B particles to the polymer blends/composites. The shear rate and frequency dependencies of the materials revealed a viscosity reduction at low (1–3 wt%) and moderate (10–15 wt%) LCP concentrations, and strong effects on the shear‐thinning characteristics of the melt. The suspensions of polydispersed Nd‐Fe‐B particle configurations in PPS that were of lower size ratios gave better processability, which is contradictory to previously reported behavior of suspensions containing spherical particles. Specifically, the compositions with unimodal and a bimodal distribution of Nd‐Fe‐B particles gave the lowest viscosities. The experimental data were correlated with semi‐empirical viscosity model equations of Maron‐Pierce, Krieger‐Dougherty, Eilers, and Thomas and were found to be consistent with the data. The maximum packing fraction, ϕ_m, of the MQP particles was estimated to be within the range of 0.78 ϕ ≤_m ≤ 1.0 through graphical and parametric evaluation methods.     

Dispersion of Poly(phenylene ether) in a Poly(phenylene sulfide)/Poly(phenylene ether) Alloy

We have devised and developed a new method for the preparation of a poly(phenylene sulfide)/poly(phenylene ether) (PPS/PPE) alloy, which has micro‐dispersed PPE in the PPS matrix. PPS was chemically treated to activate the reactivity of the PPS end‐group by extrusion in the presence of diphenylmethane diisocyanate (MDI) in its molten state at 300°C. The reactive processing of the MDI‐treated PPS with maleic anhydride‐modified PPE gave a PPS/PPE alloy with micro‐dispersed PPE in the PPS matrix. The PPS/PPE alloy showed mechanical properties superior to those of PPS at elevated temperature (150°C) and also showed precision‐molding ability superior to that of PPS.     

Liquid crystal polymer/polyethylene blends for thin film applications

A series of liquid crystal polymer/polyethylene (LCP/PE) blends have been studied to determine the potential of such a system to produce a high modulus film material which retains fabrication and low temperature characteristics of some current PE films. The subject of liquid crystalline polymer blends has been the focus of significant attention for the last decade due to the novel rheological and mechanical properties of this class of polymers. It has been demonstrated that if an LCP blend is processed under elongational flow conditions, the partially ordered LCP meso-phase intermediate allows the development of an oriented fibrillar morphology which is retained upon solidification. In this study, blown films of blends of 5 and 15% LCP in PE have been produced which show an enhancement in modulus over the neat PE matrix. These results are discussed in terms of processing conditions, LCP reinforcement aspect ratio, fibril diameter, and LCP/PE modulus ratio.     

Extruded blends of a thermotropic liquid crystalline polymer with polyethylene terephthalate,polypropylene, and polyphenylene sulfide

Structure–property relationships were investigated for blends of a polyester-type thermotropic liquid crystalline polymer (LCP) with polyethylene terephthalate (PET), polypropylene (PP), and polyphenylene sulfide (PPS). The polymers were melt blended in a twin-screw extruder and the blends were extruded to strands of different draw ratios. Tensile properties of the blends were determined as a function of LCP content and draw ratio and compared with the results of morphological and rheological analyses. In general, the strength and stiffness of the matrix polymers were improved with increasing LCP content and draw ratio. At a draw ratio of 11, the blends of PET/30 wt % LCP exhibited a tensile strength about three times and an elastic modulus nearly four times that of pure PET. All blends exhibited a skin/core morphology with thin fibrils in the skin region. The formation and the sizes of the fibril-like LCP domains in the matrices were found to depend on LCP content and the viscosity ratio of the blend components.     

In situ reactive compatibilized noryl/LCP blends

This article reveals that the already known improved properties of the thermoplastic–liquid crystalline polymer (LCP) blends can be further improved substantially over the corresponding noncompatibilized counterparts by using a reactive in situ type compatibilizer, the styrene–glycidyl methacrylate (SG) copolymer. This SG copolymer has been demonstrated in this article to be an effective reactive compatibilizer to improve the processability, heat deflection temperature, and mechanical properties of Noryl/LCP blends. The epoxy functional groups of the SG copolymer can react with the end groups of PPO (in Noryl) and LCP. The in situ-formed SG–g–LCP copolymer tends to reside along the interface of Noryl–LCP and reduces the interfacial tension during melt processing. The resultant LCP fibers in the Noryl matrix of the compatibilized blends have a higher aspect ratio because the fibers become finer, longer, and tend to form lamellate domains with a greater interphase contact area than those from the noncompatibilized blends. The compatibilized blends also improve the interphase adhesion between Noryl and LCP. The presence of ethyl triphenylphosphonium bromide catalyst promotes the grafting reaction to improve blend compatibilization. © 1995 John Wiley & Sons, Inc.     

Effects of shear rate,viscosity ratio and liquid crystalline polymer content on morphological and mechanical properties of polycarbonate and LCP blends

Studies were conducted on the effects of shear rate, viscosity ratio and liquid crystalline polymer (LCP) content on the morphological and mechanical properties of polycarbonate (PC) and LCP blends. The LCP (LC5000) used was a thermotropic liquid crystalline polymer consisting of 80/20 of parahydroxybenzoic acid and poly(ethylene terephthalate) (PHB/PET). The viscosity ratio (viscosity of LCP: viscosity of matrix) was varied by using two processing temperatures. Due to the different sensitivity of materials to temperature, variation in the processing temperature will lead to varying viscosity of the components in the blends. Based on this principle, the processing temperature could be manipulated to provide a favourable viscosity ratio of below unity for fibre formation. To study the effect of shear rate, the flow rate of the blend and the mould thickness were varied. The shear rate has a significant effect on the fibrillation of the LCP phase. The effect was more prominent when the viscosity ratio was low and the matrix viscosity was high. At 5 wt% LCP, fibrillation did not occur even at low viscosity ratios and high shear rates. It was also observed that the LCP content must be sufficiently high to allow coalescence of the dispersed phase for subsequent fibrillation to occur. © 2002 Society of Chemical Industry     

Unique orientation of lamellae in film processed poly (phenylene sulfide)

The morphology of poly(phenylene sulfide), PPS, obtained as processed film has been studied using wide angle X-ray scattering (WAXS), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). A unique morphology has been identified in the original film. The spherulites are very small in size and possess a cylindrical symmetry with their lamellae oriented on the edge. In these processed PPS films, the a-axis of the lattice is preferentially aligned perpendicular to the film plane, while the b and c axes are predominantly in the film plane. In the PPS isothermally crystallized from the melted, original film, there is no such preferential orientation. Thermal analysis of the original and melt crystal-lized PPS shows that while the degree of crystallinity is about the same, the nature of the amorphous phase in the two materials is different. In the original film, we did not observe a heat capacity increment at a glass transition temperature by DSC, indicating that all of the amorphous phase belongs to the category of rigid amorphous phase. In the melt crystallized PPS, a distinct glass transition was seen, though only a portion of the amorphous phase becomes mobile at T_g. The differences in orientation and mobility of the amorphous phase in the original film compared to melt crystallized PPS are explained by the different thermal processing procedures used for the two materials.     

Elastomer-toughened poly(phenylene sulfide)

For use as electrical and electronics parts, or automobile and mechanical parts, toughened poly(phenylene sulfide) (PPS) is desired. For these applications, our investigation centered on improving the toughness of PPS and developing elastomer-toughened PPS and elastomer-toughened compounds of PPS. Using chemically treated PPS and an olefinic elastomer with a functional group, we developed elastomer-toughened PPS using a reactive processing method. In the PPS matrix, the elastomer is finely dispersed. While the notched Izod impact strength of the original PPS is about 1 kg · cm/cm. clastomer-toughened PPS has a notched impact strength around 50 kg · cm/cm. The notched fracture surface of elastomer-toughened PPS is observed using a scanning electron microscope. We concluded that the mechanism for the toughening is attributed to energy dissipation by matrix yield.     

Mechanical and morphological study of polyphenylene sulfide/liquid crystalline polymer blends compatibilized with a maleic anhydride grafted copolymer

Blends of thermotropic liquid crystalline polymer (LCPA‐950), based on a copolyester of hydroxynapthoic acid and hydroxybenzoic acid with an engineering thermoplastic, poly(phenylene sulfide) (PPS), were prepared using a corotating twin‐screw extruder. Addition of a third component, a functionalized polypropylene (maleic anhydride grafted polypropylene, MA‐PP), that interact with the thermotropic liquid crystalline polymer (TLCP) facilitates the structural development of the TLCP phase by acting as a compatibilizer at the interface. Differential scanning calorimetry and dynamic mechanical thermal analysis results, however, show that there is an interaction between the polymers in the presence of compatibilizer. This means that MA‐PP can be used as a compatibilizer for the PPS/LCP in situ composite system. The viscosity of the compatibilized in situ composite was decreased by the compatibilizer, and this is mainly due to the fibrous structure of the LCP at the high shear rate. The mechanical properties of the ternary blends were increased when a proper amount of MA‐PP was added. This is attributed to fine fibril generation induced by the addition of MA‐PP. Morphological observations determined the significance of the third component in immiscible polymer blends, and an optimum amount of MA‐PP exists for the best mechanical performance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Morphology and mechanical properties of liquid crystalline copolyester and polyester elastomer blends

Blends of a polyester elastomer (PEL) having a hard segment of polyester (PBT) and soft segment of polyether (PTMG) and a liquid crystalline copolyester (LCP), poly(benzoate-naphthoate), were prepared in a twin-screw extruder. Specimens for mechanical testing were prepared by injection molding. The morphology of the LCP/PEL blends was characterized under different processing conditions. To determine what conditions were necessary for the development of a fibrillar morphology of LCP, we have studied the effect of processing method (extrusion and injection molding), injection molding temperature (below and above the melting point of LCP), and gate position in the mold (direct gate and side gate). SEM studies revealed that some extensional flow was required for the fibrillar formation of LCP and the fibrillar structure of LCP was controlled by the processing method. The morphology of the blends was found to be affected by their compositions and processing conditions. SEM studies revealed that finely dispersed spherical domains of LCP were formed in the PEL matrix and the inclusions were deformed in fibrils from the spherical droplets with increasing LCP content and injection temperature. The mechanical properties of the LCP/PEL blends were also found to be affected by their compositions and processing conditions. The mechanical properties of LCP/PEL blends were very similar to those of polymeric composite. An attempt was made to correlate the structure of the blends from the scanning electron microscope with the measured mechanical properties. All of the aspects of the morphology were possible to explain in terms of the mechanical properties of the blends. A DSC study revealed that the crystallization of PEL was accelerated by the addition of LCP in the matrix and a partial compatibility between LCP and PEL was predicted. The rheological behavior of the LCP/PEL blends was found to be very different from that of the parent polymers, and significant viscosity reductions were observed in the blend consisting of only 5 wt% of LCP.     

火焰喷涂改良型聚苯硫醚涂层研究

为了能将聚苯硫醚（ＰＰＳ）用于现场涂装，本文采用火焰喷涂法制得了改良型ＰＰＳ涂层，初步考察了不同类型，不同分子量的ＰＰＳ以及喷涂工艺对涂层性能的影响，结果表明，在一定的喷涂工艺条件下，中等分子量和高分子量的改良型ＰＰＳ比通用型ＰＰＳ涂层的成膜性，韧性和附着力都好。     

Thermal and crystallization behavior of engineering polyblends. II. Unfilled polyphenylene sulfide with poly(ethylene terephthalate)

The melting and crystallization behavior of blends of poly(phenylene sulfide) (PPS) with poly(ethylene terephthalate) (PET) has been investigated. The component polymers in the blend exhibited separate crystallization peaks and overlapping melting peaks. The nonisothermal DSC scans indicated that the crystallization parameters for PET become modified to a greater extent than do those for PPS in the blends. The PET crystallization peak became narrower with a higher heat of crystallization, suggesting a faster rate of crystallization as a result of blending with PPS. The isothermal crystallization studies revealed that the nucleation of PPS is facilitated by the presence of PET. This contention has been substantiated by polarized light microscopic observations. The spherulites of PPS were found to be smaller in the blends as compared to those in neat PPS. This enhancement in the nucleation of PPS has been attributed to the possibilities of chemical interactions between the component polymers. On the other hand, the increase in the rate of crystallization of PET has been attributed to the heterogeneous nucleation provided by the alreadycrystallized PPS. The melt crystallized blends exhibited slightly higher heats of fusion compared to the values computed from the rule of proportional additivity. © 1994 John Wiley & Sons, Inc.