Creep and recovery behavior of novel organic‐inorganic polymer hybrids

A novel class of organic‐inorganic polymer hybrids were developed by meltblending up to 50 (v/v) % [about 83 (w/w) %] tin‐based polyphosphate glass (Pglass) and low‐density polyethylene (LDPE) in conventional plastics processing equipment. The creep and recovery behavior of these polymer hybrids at 30°C were studied to understand the effect of the Pglass on the creep resistance of the LDPE. The results suggest that the Pglass acts as a reinforcement and an increase in the Pglass loading leads to significantly lower creep strains. This creep resistance is further enhanced by pretreating the Pglass with coupling agents prior to incorporating them into the Pglass‐LDPE hybrids. The experimental creep compliance of these materials conformed excellently with empirical power‐law equation and a modified Burger's model, suggesting that the materials are linearly viscoelastic under the test conditions.     

Crystallization kinetics of low‐density polyethylene and polypropylene melt‐blended with a low‐Tg tin‐based phosphate glass

The nonisothermal and isothermal crystallizations of low‐density polyethylene (LDPE) and polypropylene (PP) in phosphate glass (Pglass)–polymer hybrid blends were studied through differential scanning calorimetry (DSC). As the Pglass volume fraction was increased, the percentage crystallinity decreased. The half‐time for crystallization decreased as the propagation rate constant rose, for both of the polymer matrices, with increasing Pglass concentrations. The Pglass was observed to be a nucleating agent for formation of two‐ or three‐dimensional spherulites in the hybrids. Tensile modulus improved for both of the Pglass–polymer hybrids up to 40% Pglass, but the energy to break decreased. Tensile strength changed slightly with the addition of Pglass to the LDPE matrix, exhibiting a larger value than that of pure LDPE at 30%. The tensile strength decreased as more Pglass was added to the PP matrix. The observed differences between tensile properties of the Pglass–PP and Pglass–LDPE hybrids at identical Pglass volume concentration were found to be consistent with that of the crystallization behavior of the hybrids. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3445–3456, 2003     

An experimental study of morphology and rheology of ternary Pglass‐PS‐LDPE hybrids

Ternary blends of low‐density polyethylene (LDPE), polystyrene (PS), and a low T_g tin‐based phosphate glass (Pglass) were prepared at compositions ranging from 0–50 vol% Pglass in which either LDPE or PS was the continuous matrix phase. Differential scanning calorimetry was used to investigate the phase behavior of the pure components, PS‐LDPE blends and binary Pglass‐polymer hybrids. Interesting steady‐shear and transient rheology was observed for the hybrids. In particular, the steady shear viscosity curves for the hybrids of ?_Pglass ≤ 30% exhibited unusual, four‐region flow behavior, similar to that of liquid crystalline polymers. Two Newtonian plateaus at low (${\rm \dot \gamma }$ ≤ 0.1 s^?1) and moderate (0.4 ≤ ${\rm \dot \gamma }$ ≤ s^?1) shear rates connected by two distinct shear‐thinning regimes were apparent. This observed rheology is ascribed to a unique composite morphology of these multi‐component systems. Rheological data on the binary Pglass‐polymer systems suggest that the presence of the Pglass within both PS and LDSE contributes significantly to this unusual behavior, perhaps because of the interfacial behavior between the phases. Micrographs obtained via scanning electron microscopy reveal preferential placement of the Pglass phase dispersed within the PS‐phase and surrounding the LDPE phase. Optical shearing data confirmed the evolution of this microstructure under specific shear conditions.     

Investigation of phase behavior during melt processing of novel inorganic‐organic polymer hybrid material

The phase behavior of novel, binary organic‐inorganic hybrids consisting of an ultra‐low T_g tin‐based phosphate glass (Pglass) and polystyrene (PS) was investigated. Dynamic mechanical analysis (DMA) revealed that the glass transition peaks of the PS changed slightly with Pglass volume fraction, leading to a broad peak at the phase inversion point. The phase inversion and degree of phase continuity of the hybrid were studied through solvent extraction, optical/scanning electron microscopy, and dynamic rheology. The Jordhamo and Utracki viscosity ratio models provided reliable estimates of the inversion point. Torque rheometry revealed a trend toward linear additivity within the temperature range 200°C–230°C. Small‐angle neutron scattering experiments gave further evidence of the hybrid phase incompatibility. The results of this study point to a promising new class of blend materials with the potential to present a unique combination of properties impossible to achieve with classical polymer blends. Polym. Eng. Sci. 44:1692–1701, 2004. © 2004 Society of Plastics Engineers.     

Study of the effects of melt blending speed on the structure and properties of phosphate glass/polyamide 12 hybrid materials

The effects of melt blending conditions on the rheology, crystallization kinetics, and tensile properties of phosphate glass/polyamide 12 hybrid systems were investigated for the first time, to understand their complex processing/structure/property relationships. Increasing amounts of phosphate glass (Pglass) caused an increase in hybrid viscosity. Hybrid viscosity was also affected by processing (melt‐mixing) speed and small‐amplitude oscillatory shear tests and scanning electron microscopy (SEM) were used for a qualitative examination of the hybrid morphology. The addition of Pglass caused a decrease in hybrid crystallinity that was unaffected by processing (melt‐mixing) speed. The two‐parameter Avrami equation was applied successfully to the hybrid systems, and Pglass was found to nucleate the growth of polyamide 12 crystals. The nucleation effect was found to be dependent on concentration and processing history. The tensile properties of the hybrids were also studied, and the Halpin–Tsai equation was applied to the results to determine the maximum packing fraction of the Pglass. These results provide a basis for the prediction of hybrid mechanical properties for different Pglass concentrations and processing histories. Further, because of their facile processibility and desirable characteristics, such as the strong physicochemical interaction between the hybrid components and favorable viscoelasticity, these Pglass/polyamide 12 hybrids can be used as model systems for exploring feasibility of new routes for driving organic polymers and inorganic Pglass to self‐assemble into useful organic/inorganic hybrid materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

New phosphate glass/polymer hybrids—Current status and future prospects

The physical modification of polymer structure and properties via polymer blending and reinforcement is a common practice in the plastics industry and has a large economic advantage over synthesizing new polymeric materials to fulfill new material needs. In this context, a new class of inorganic glass/organic polymer hybrids with enhanced benefits has been recently developed by blending low-Tg phosphate glasses with polymeric materials in the liquid state, to afford new hybrid materials with significant improvements in properties that are impossible to achieve from classical polymer blends and composites. Because of their facile synthesis and desirable characteristics, these phosphate glass/polymer hybrid materials may be model systems for exploring feasibility of new routes for driving inorganic glasses and organic polymers to self-assemble into useful materials. Conceptually, it may even be possible to use block copolymers, with one block being miscible with Pglass, to perform self-directed assembly of nanostructured hybrids, where the Pglass is confined solely to one phase. This article reviews some new insights into the structural dynamics, melt rheology, molecular relaxation processes, and phase behavior of a few representative examples of these unique hybrid materials with prescribed rheological properties, macromolecular structure and function. The unanswered questions are discussed to guide future research directions, and facilitate progress in this emerging area.     

Unusual accelerated molecular relaxations of a tin fluorophosphate glass/polyamide 6 hybrid studied by broadband dielectric spectroscopy

Phosphate glass (Pglass)/polymer hybrids are a relatively new class of materials that combine the advantages of classical polymer blends and composites without their disadvantages. In the case of highly interacting Pglass/polymer (i.e., polyamide 6) hybrids, counter-intuitive properties that are difficult to explain are often observed. To shed light into the origins of the special behavior of the hybrids, we investigated the molecular relaxation processes in the hybrids using broadband dielectric spectroscopy. The dielectric loss spectra were fitted with the Havriliak-Negami equation and the characteristic relaxation times of the hybrid and the pure components were observed. The temperature dependence of the characteristic relaxation times was described using either the Vogel-Fulcher-Tammann, for the α-relaxations, or an Arrhenius type equation, for the β- and γ-relaxations. The addition of Pglass greatly accelerated both the α- and β-relaxations of the polyamide 6. However, the γ-relaxation was found to be independent of Pglass composition. This suggests partial miscibility in the solid state, which was confirmed via NMR spectroscopy. The unexpected dramatic change in the β-relaxation process in the 10 vol.% Pglass hybrid suggests that blending can change the local environment of polyamide 6 due to the nanoscale morphology of this system as confirmed by TEM and NMR. It is thought that the fraction of miscible Pglass disrupts the hydrogen bonding between polyamide 6 chains and thereby reduces coordinated, multiple chain motion. In turn, this produces a plasticization effect and possible modification of the polyamide 6's crystalline structure in the Pglass/polyamide 6 hybrids.     

Toward forced assembly of in situ low‐density polyethylene composites reinforced with low‐Tg phosphate glass fibers: Effects of matrix crystallization and shear deformation

This study is aimed at investigating the feasibility of using facile forced assembly methods (temperature and shear strain‐induced orientation of the dispersed phase) to create novel “in situ” low‐density polyethylene (LDPE) composites containing fibrillar inorganic phosphate glass (P‐glass) reinforcing phase during the composite fabrication. Clearly, the experimental results show that unique thermo‐rheological conditions exist under which the “in situ” LDPE composites containing fibrillar P‐glass with potential enhanced benefits can be prepared. DSC results showed that the P‐glass has a moderate nucleating effect on the LDPE crystallization that restricts in situ deformation of the P‐glass during the composite fabrication. Rheo‐optical data showed that a 5% P‐glass/95% LDPE hybrid composition, subjected to a shear rate of 20 s^?1 in the parallel plate configuration and 130°C gave “in situ” LDPE composite samples with the largest amount of P‐glass fibers in the limited range of experimental conditions used. This study may spur interests in a better understanding of the potential for the “in situ” reinforcement of engineering plastics with inorganic P‐glasses, at the molecular level, to produce novel “in situ” polymer composites with very high aspect ratios of the reinforcing inorganic phase. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Formation of macroporous organic‐inorganic polymer hybrids using tea extract

Macroporous organic–inorganic polymer hybrids were prepared from poly(vinyl pyrrolidone), and inorganic alkoxides. To a reaction mixture of poly(vinyl pyrrolidone) and tetramethoxysilane, extract from tea leafs and HCl aqueous solution in methanol were added. The resulting mixture was constantly stirred at room temperature for 1 h and heated at 60°C for two weeks. Consequently, the corresponding polymer hybrid became a macroporous material having a pore size from 3.26 to 20.86 μm. We succeeded in finding that the pruned tea leafs were able to utilize the synthesis of novel macroporous materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Recycling of poly(ethylene terephthalate) as polymer‐polymer composites

Microfibrillar reinforced composites (MFC) comprising an isotropic matrix from a lower melting polymer reinforced by microfibrils of a higher melting polymer were manufactured under industrially relevant conditions and processed via injection molding. Low density polyethylene (LDPE) (matrix) and recycled poly(ethylene terephthalate) (PET) (reinforcing material) from bottles were melt blended (in 30/70 and 50/50 PET/LDPE wt ratio) and extruded, followed by continuous drawing, pelletizing and injection molding of dogbone samples. Samples of each stage of MFC manufacturing and processing were characterized by means of scanning electron microscopy (SEM), wide‐angle X‐ray scattering (WAXS), dynamic mechanical thermal analysis (DMTA), and mechanical testing. SEM and WAXS showed that the extruded blend is isotropic but becomes highly oriented after drawing, being converted into a polymer‐polymer composite upon injection molding at temperatures below the melting temperature of PET. This MFC is characterized by an isotropic LDPE matrix reinforced by randomly distributed PET microfibrils, as concluded from the WAXS patterns and SEM observations. The MFC dogbone samples show impressive mechanical properties—the elastic modulus is about 10 times higher than that of LDPE and about three times higher than reinforced LDPE with glass spheres, approaching the modulus of LDPE reinforced with 30 wt% short‐glass fibers (GF). The tensile strength is at least two times higher than that of LDPE or of reinforced LDPE with glass spheres, approaching that of reinforced LDPE with 30 wt% GF. The impact strength of LDPE increases by 50% after reinforcement with PET. It is concluded that: (i) the MFC approach can be applied in industrially relevant conditions using various blend partners, and (ii) the MFC concept represents an attractive alternative for recycling of PET as well as other polymers.     

Crystallization of low‐density polyethylene‐ and linear low‐density polyethylene‐rich blends

The crystallization of a series of low‐density polyethylene (LDPE)‐ and linear low‐density polyethylene (LLDPE)‐rich blends was examined using differential scanning calorimetry (DSC). DSC analysis after continuous slow cooling showed a broadening of the LLDPE melt peak and subsequent increase in the area of a second lower‐temperature peak with increasing concentration of LDPE. Melt endotherms following stepwise crystallization (thermal fractionation) detailed the effect of the addition of LDPE to LLDPE, showing a nonlinear broadening in the melting distribution of lamellae, across the temperature range 80–140°C, with increasing concentration of LDPE. An increase in the population of crystallites melting in the region between 110 and 120°C, a region where as a pure component LDPE does not melt, was observed. A decrease in the crystallite population over the temperature range where LDPE exhibits its primary melting peaks (90–110°C) was noted, indicating that a proportion of the lamellae in this temperature range (attributed to either LDPE or LLDPE) were shifted to a higher melt temperature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1009–1016, 2000     

Melt rheological behavior of intimately mixed short sisal–glass hybrid fiber‐reinforced low‐density polyethylene composites. I. Untreated fibers

The melt rheological behavior of intimately mixed short sisal–glass hybrid fiber‐reinforced low‐density polyethylene composites was studied with an Instron capillary rheometer. The variation of melt viscosity with shear rate and shear stress at different temperatures was studied. The effect of relative composition of component fibers on the overall rheological behavior also was examined. A temperature range of 130 to 150°C and shear rate of 16.4 to 5470 s^?1 were chosen for the analysis. The melt viscosity of the hybrid composite increased with increase in the volume fraction of glass fibers and reached a maximum for the composite containing glass fiber alone. Also, experimental viscosity values of hybrid composites were in good agreement with the theoretical values calculated using the additive rule of hybrid mixtures, except at low volume fractions of glass fibers. Master curves were plotted by superpositioning shear stress and temperature results. The breakage of fibers during the extrusion process, estimated by optical microscopy, was higher for glass fiber than sisal fiber. The surface morphology of the extrudates was analyzed by optical and scanning electron microscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 432–442, 2003     

Dynamic and capillary rheology of LDPE‐EVA–based thermoplastic elastomer: Effect of silica nanofiller

The effect of pristine silica nanoparticles on the dynamic and capillary rheology of a model LDPE‐EVA thermoplastic elastomeric system is explored in this paper. The pristine silica nanoparticles were melt‐blended with the LDPE‐EVA system at 1.5, 3, and 5 wt% loadings, respectively, by varying the sequence of addition. In one of the compositions, coupling agent bis‐[3‐(triethoxysilyl)propyl] tetrasulphide (Si‐69) was used to improve the interaction of hydrophilic silica particles with polymer matrix. Results obtained reveal that the viscoelastic behavior of such composites is influenced remarkably by loadings of silica, variation of sequence, and addition of Si‐69. Upon addition of coupling agent, G′ value increases especially at higher strain levels due to increased polymer‐filler interactions. All systems with various loading of nanosilica represent an increase in elastic response with increasing frequency. Both the unfilled and filled blends exhibit rheological behavior of non‐Newtonian fluids. But interestingly, the viscoelastic response varies markedly with the temperature. The dynamic and steady shear rheological properties register a good correlation in regard to the viscous vs. elastic response of such systems. Finally, the rheological behavior is correlated with morphology of the present system processed at various shear rates. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Mechanical and thermal properties of polyimide/silica hybrids with imide‐modified silica network structures

A series of hybrid materials incorporating imide‐modified silica (IM‐silica) network structures into a polyimide (PI) matrix were produced with a sol–gel technique from solution mixtures of poly(amic acid) and tetraethoxysilane (TEOS) containing alkoxysilane‐terminated amic acids with various degrees of polymerization. The hybrid films, obtained by solvent evaporation, were heated successively to a maximum temperature of 300°C to carry out the imidization process and silica network formation in the PI matrix. The morphology and mechanical properties of these hybrids with IM‐silica networks were studied and compared with the properties of one in which reinforcement of the matrix was achieved with a pure silica network generated from TEOS. The introduction of longer imide spacer groups into the silica network led to a drastic decrease in the silica particle size. Improved tensile modulus was observed in such compatibilized hybrid systems. Comparative thermogravimetric measurements of these hybrids showed improved thermooxidative resistance. A PI hybrid with 30% IM‐silica had a thermal decomposition temperature nearly 260°C higher than that of the pure PI matrix. The high surface area of the interconnected silica domains and increased interfacial interaction were believed to restrict the segmental motion of the polymer and thus slow the diffusion of oxygen in the matrix, thereby slowing the oxidative decomposition of the polymer. The reinforcement of existing and new PIs by this method offers an opportunity for improving their thermooxidative stability without degrading their mechanical strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(vinyl alcohol)/water glass (SiO2) nano‐hybrids via sol‐gel process

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as catalyst supporting. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with water glass. The inorganic phase was also modified by incorporating a hexamethyldisiloxane as precursor. The hybrid aerogel powder was analyzed by scanning electron microscopy, TG‐DTA, Nitrogen adsorption–desorption, X‐ray diffraction and fourier transform infrared spectroscopy (FTIR) spectroscopy. The powder obtained had a higher porosity varying from 65 to 90% and the nanopore diameter ranged from 17 to 20 nm. The surface area and nanopore volume decreased as polymer content increased in the hybrids. The sharp decline in the weight observed at around 500°C accompanied an exothermic peak of the DTA curve. The sharp peak was observed around 211°C represents the DTA curve of Poly vinyl alcohol constituent in nano hybrids. The peak at 1638 cm^?1 in the FTIR indicated the formation of Si? O? PVA? O? Si bridge in aerogel powder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Simulation of nonisothermal flow of melt during melting process of vibration‐induced polymer extruder

A simplified 2D melt film model was established to simulate the nonisothermal melt flow during the melting process of the vibration‐induced polymer extruder of which the screw can vibrate axially. Since polymer has time‐dependent nonlinear viscoelastic characteristic with vibration force filed (VFF), a self‐amended nonisothermal Maxwell constitutive equation that can reflect the relaxation time spectrum of polymer was adopted. Using the 2D melt film model, melt films of two kinds of thickness representing different melting stages were simulated to investigate the influence tendency of the same VFF on the different melting stage. Special flow patterns and temperature distribution of melt in the melt film between the driving wall and the solid/melt interface with various vibration force fields were systematically simulated. It is found out that within a certain range of vibration strength, the application of vibration can optimize the time‐averaged shear‐rate distribution, improve the utilization efficiency of energy, and promote melting process; and the thinner the melt film is, the more intense the nonlinear viscoelastic response becomes with the same VFF; moreover, there exists optimum vibration strength to make the melting process fastest, which is in accord with the visualization experimental results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5825–5840, 2006     

Preparation of viscoelastic gel‐like halloysite hybrids and their application in halloysite/polystyrene composites

Self‐reinforcement gel‐like halloysite nanotube (g ‐HNT ) hybrids with various viscoelastic behaviors were fabricated by firstly treating with various concentrations of sodium hydroxide (NaOH ) solution and then grafting tertiary amine and ion‐exchange reacting with sulfonate anions. The morphology, composition, thermal stability and rheological behavior of the g ‐HNT hybrids were systematically characterized and analyzed using various methods. It is found that the viscoelasticity of g ‐HNT hybrids can be easily regulated by using different NaOH solution‐treated HNTs as inorganic core and temperatures. In addition, the g ‐HNT hybrids treated with medium concentration of NaOH (0.06 mol L^?1) have the lowest viscosity and highest level of dispersion compared with those treated with other concentrations of NaOH solution. Due to the amphiphilic nature of g ‐HNT hybrids and their lower viscosity than HNT powder, as novel hybrid fillers, they were utilized to prepare polystyrene composites by direct melt blending for achieving simultaneous reinforcement and plasticization effects. Besides the above mentioned advantages, the thermal conductivity of polystyrene composites is also surprisingly improved by reducing the interfacial mismatch between the filler and polymer matrix. The solvent‐free and self‐reinforcement hybrids provide a convenient and green path for fabricating high‐performance polymer composites. © 2017 Society of Chemical Industry     

Structure and dynamics of polyethylene/clay films

The relationships between structure and rheology of polyethylene/clay hybrid composite blown films were investigated through rheological tests both in shear and elongational flow. Two polymer matrices (low density polyethylene, LDPE and linear low density polyethylene, LLDPE) with different relaxation kinetics were used. Independently from the matrix, morphological analyses (TEM, XRD, and SEM) indicate that the hybrid structures are similarly constituted of delaminated platelets or tactoids having a relevant degree of orientation along the draw direction. This strongly affects the rheological behavior of materials. However, despite the similarities emerged from morphological analyses, both shear (steady shear and oscillatory) and elongation measurements show a negligible effect upon the rheology of LDPE‐based nanohybrids. Conversely, relevant increases of shear viscosity, dynamic moduli and melt strength of LLDPE‐based nanohybrids have been detected. The effects of homopolymer relaxation kinetics have been investigated by means of stress relaxation tests. The results obtained seem to be consistent with the existence of a roughly bimodal population of dynamical species: a matrix component behaving like the homopolymer, and a fraction interacting with the filler, whose rheological behavior is controlled by the particles and their interactions with the polymer. Mechanical properties of hybrid films were also investigated. Differently from what happens in the melt state, the solid‐state properties mainly depend on the filler amount. The relative increases of tensile modulus and melt strength are of the same order of magnitude for both the matrices used, indirectly confirming the similarities in hybrids structures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4749–4758, 2006     

In situ composites from blends of polycarbonate and a thermotropic liquid‐crystalline polymer: The influence of the processing temperature on the rheology,morphology, and mechanical properties of injection‐molded microcomposites

This work was aimed at understanding how the injection‐molding temperature affected the final mechanical properties of in situ composite materials based on polycarbonate (PC) reinforced with a liquid‐crystalline polymer (LCP). To that end, the LCP was a copolyester, called Vectra A950 (VA), made of 73 mol % 4‐hydroxybenzoic acid and 27 mol % 6‐hydroxy‐2 naphthoic acid. The injection‐molded PC/VA composites were produced with loadings of 5, 10, and 20 wt % VA at three different processing barrel temperatures (280, 290, and 300°C). When the composite was processed at barrel temperatures of 280 and 290°C, VA provided reinforcement to PC. The resulting injection‐molded structure had a distinct skin–core morphology with unoriented VA in the core. At these barrel temperatures, the viscosity of VA was lower than that of PC. However, when they were processed at 300°C, the VA domains were dispersed mainly in spherical droplets in the PC/VA composites and thus were unable to reinforce the material. The rheological measurements showed that now the viscosity of VA was higher than that of PC at 300°C. This structure development during the injection molding of these composites was manifested in the mechanical properties. The tensile modulus and tensile strength of the PC/VA composites were dependent on the processing temperature and on the VA concentrations. The modulus was maximum in the PC/VA blend with 20 wt % VA processed at 290°C. The Izod impact strength of the composites tended to markedly decrease with increasing VA content. The magnitude of the loss modulus decreased with increasing VA content at a given processing temperature. This was attributed to the anisotropic reinforcement of VA. Similarly, as the VA content increased, the modulus and thus the reinforcing effect were improved comparatively with the processing temperature increasing from 280 to 290°C; this, however, dropped in the case of composites processed at 300°C, at which the modulus anisotropy was reduced. Dynamic oscillatory shear measurements revealed that the viscoelastic properties, that is, the shear storage modulus and shear loss modulus, improved with decreasing processing temperatures and increasing VA contents in the composites. Also, the viscoelastic melt behavior (shear storage modulus and shear loss modulus) indicated that the addition of VA changed the distribution of the longer relaxation times of PC in the PC/VA composites. Thus, the injection‐molding processing temperature played a vital role in optimizing the morphology‐dependent mechanical properties of the polymer/LCP composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Solid polymer electrolytes. XI. Preparation,characterization and ionic conductivity of new plasticized polymer electrolytes based on chemical‐covalent polyether–siloxane hybrids

A new hybrid polymer electrolyte system based on chemical‐covalent polyether and siloxane phases is designed and prepared via the sol–gel approach and epoxide crosslinking. FT‐IR, ¹³C solid‐state NMR, and thermal analysis (differential scanning calorimetry (DSC) and TGA) are used to characterize the structure of these hybrids. These hybrid films are immersed into the liquid electrolyte (1M LiClO₄/propylene carbonate) to form plasticized polymer electrolytes. The effects of hybrid composition, liquid electrolyte content, and temperature on the ionic conductivity of hybrid electrolytes are investigated and discussed. DSC traces demonstrate the presence of two second‐order transitions for all the samples and show a significant change in the thermal events with the amount of absorbed LiClO₄/PC content. TGA results indicate these hybrid networks with excellent thermal stability. The EDS‐0.5 sample with a 75 wt % liquid electrolyte exhibits the ionic conductivity of 5.3 × 10^?3 S cm^?1 at 95°C and 1.4 × 10^?3 S cm^?1 at 15°C, in which the film shows homogenous and good mechanical strength as well as good chemical stability. In the plot of ionic conductivity and composition for these hybrids containing 45 wt % liquid electrolyte, the conductivity shows a maximum value corresponding to the sample with the weight ratio of GPTMS/PEGDE of 0.1. These obtained results are correlated and used to interpret the ion conduction behavior within the hybrid networks. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1000–1007, 2006