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An environmentally friendly free-carrier technique was used to prepare poly propylene/poly(trimethylene terephthalate) (PP/PTT) blend fibers. As PTT loading increased, its average diameter enhanced, and its distribution narrowed. In addition, the results of mechanical properties demonstrated that incorporating PTT into the PP matrix led to a decrease in tenacity and elongation-at-break. The more the PTT content, the less the tenacity and the elongation-at-break. Moreover, the crystallinity of PP enhanced by about 12% when 20 wt.% PTT was incorporated while melting and crystallization temperatures did not change remarkably. The molten blends indicated almost a Newtonian behavior. On the other hand, the storage modulus enhanced almost linearly in the frequency range of 1–1000 1/sec for all samples. Also, approximately 60% improvement in dyeability and 10% progress in resiliency behavior were observed. The dye uptake ability of samples was improved with the addition of PTT. In addition, the washing and light fastness of the blends were admissible for textile fibers. Generally, blends with PTT content less than 20 wt.% exhibited better physical and mechanical properties, especially resiliency behavior. Therefore, PP/PTT blend fibers are promising candidates for use in textiles in the coming years. [ABSTRACT FROM AUTHOR]

The increasing concern about the environment has enhanced the utilization of sustainable products in every field of life, from common household items to fabrics. Although cotton is a plant-based fiber, its cultivation requires large amounts of water and pesticides. Therefore, the future of product development demands environmental friendliness. To overcome the problems of cotton related to the environment, a novel sustainable fabric was developed by using Tencel and jute fiber for the apparel industry to reduce the usage of cotton. In this current study, six blended yarns of two counts (10 & 20 Ne) of Tencel and jute (90:10, 80:20, and 70:30) were developed by ring spinning to weave fabric in two weave designs (Plain & Twill). These developed fabrics were assessed for mechanical, comfort, and hand properties. The results revealed that the blended fabric with a high content of Tencel is good in terms of mechanical, comfort, and hand properties, except for stiffness, pilling resistance, resilience, and drapeability. Additionally, fabric woven with a fine yarn count is also good in the above-stated properties, except for stiffness, resilience, and wrinkle recovery. However, fabrics woven with a twill weave design have good comfort and hand properties, except for smoothness and drapability. On the other hand, fabric with a plain weave design is good in terms of mechanical properties, except for tear strength. The comparison of TJ blended fabric with PC blended fabric shows that the tensile strength, air permeability and OMMC of JT blended fabric is 8.31%, 96%, and 29.46% higher than PC blended fabric but tear strength is 99% less. Furthermore, statistical analysis was performed to check the effect of the input variables on the response factors, and it was found that the effect of yarn count on all output responses is statistically the most significant. [ABSTRACT FROM AUTHOR]

To achieve increased flow and reduce fouling, polymeric membranes can be functionalized with hydrophilic groups such as sulfone, amines, and others. This research has aimed at the sulfonation of Polysulfone (PSU) with various agents and at varying substitution degrees to change its hydrophobic character. PSU was also blended with Poly(lactic acid) (PLA), which is a more hydrophilic polymer. The phase inversion method was used to make PSU, PLA, sulfonated PSU, and PSU/PLA blend-based membranes. Sulfonation degrees of sulfonated PSU membranes were assessed using FT-IR, mechanical characteristics of membranes were determined, and thermal properties of membranes were clarified using DSC and TGA techniques. Hydrophilic natures and membrane alterations were investigated, as well as contact angle and water uptake measures. Among three distinct sulfonation agents (trimethylsilyl chlorosulfonate (TMSCS), sulfuric acid, and chlorosulfonic acid) employed to produce a 20% sulfonation degree of polysulfone, TMSCS was chosen as having the highest sulfonation efficiency (91.5%). With increasing sulfonation degree, a drop in molecular weight was seen in all sulfonated polysulfone samples. The mechanical strength values of polysulfone after sulfonation with TMSCS rose from 35.23 MPa to 63.35 MPa, while the contact angle value decreased from 85.58° to 71°. The contact angle value reduced from 85.58° to 64.68° while the mechanical strength of the PSU and PSU/PLA (50:50) blend increased from 35.23 MPa to 39.3 MPa. Membranes were also tested for pure water flux, hydrostability, and biostability. In terms of application requirements, it was determined that sulfonated PSU-based membranes manufactured with TMSCS with a 20% sulfonation degree and PSU/PLA blend-based membranes with a 50:50 (w:w) ratio have the optimum compositions with high flux quantities. [ABSTRACT FROM AUTHOR]

The mechanical properties of γ-irradiated ethylene propylene diene monomer (EPDM)/high styrene-butadiene rubber (HSBR) blends were investigated with special reference to the effects of blend ratio. Among the blends, the one with 80/20 EPDM/HSBR has been found to exhibit the highest tensile, hardness, thermal, and abrasion properties. The effect of γ-irradiation dose on the mechanical properties namely tensile strength and elongation at break was investigated. The effect of silane coupling agent on the mentioned properties of the EPDM/HSBR blend was studied. The results showed that the mechanical and the thermal properties of the γ-irradiated EPDM/HSBR blend improved with the addition of the silane coupling agent due to the increase in the cross-linking density. The inclusion of both the 30 phr fumed silica and N, N - m -phenylenedimaleimide coagent in the 80/20 EPDM/HSBR nanocomposite irradiated to 150 kGy leads to a synergistic effect. Thermogravimetric analysis was carried out to analyze the thermal stability of the nanocomposites. The mechanical properties have been interpreted in terms of the morphology of the blends as attested by scanning electron microscope. [ABSTRACT FROM AUTHOR]

A kind of modified bismaleimide resin, with good processability, heat resistance, and impact strength was developed, using 4,4′-dipropargyloxydiphenyl ether (DPEDPE), N -(4-propargyloxyphenyl)maleimide (4-PPM), and 3-ethynylphenyl maleimide (3-EPM) as modifiers. The DPEDPE, 4-PPM, and 3-EPM were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and 1H-nuclear magnetic resonance (1H NMR), and used to modify the N,N ′-(4,4′-diphenylmethane)bismaleimide (BDM)/2,2′-diallyl bisphenol A (DABPA) resin system (BD) to obtain the different blend resin systems of DPEDPE-modified BD (BDD), 4-PPM-modified BD (BDP), and 3-EPM-modified BD (BDE). The curing temperature of BD resin increases with increase of the alkynyl-terminated modifier content. The processability of BD resin was improved with addition of the propargyloxy-terminated compounds. The temperature of 5% weight loss, residual yield at 800°C and glass transition temperature of the cured BD resin increase with increase of the alkynyl-terminated modifier content and can reach 443°C, 46.7% and higher than 380°C. The tensile strength of the cured BD resin decreases with increase of alkynyl-terminated modifier content. The impact strength of the cured BD resin increases with increase of the propargyloxy-terminated compound content and can increase by 65%. The tensile strength, elastic modulus, and impact strength of the cured BD resin blended with DPEDPE can be 73.7 MPa, 4.1 GPa, and 19.6 kJ m−2, respectively. Moreover, the cured BD resin blended with DPEDPE has good water absorption resistance. [ABSTRACT FROM AUTHOR]

The effect of electron beam (e-beam) irradiation on the thermal and mechanical properties of ethylene-vinyl acetate copolymer/ternary polyamide (EVA/tPA) blends was studied. The e-beam irradiation was carried out over a range of dose from 50 kGy to 500 kGy with trimethylolpropane trimethacrylate (TMPTMA) and triallyl isocyanurate (TAIC) as cross-linking coagents. With increasing irradiation dose, the gel fraction of the EVA/tPA blends increased significantly. After irradiated by e-beam at 500 kGy, the insoluble fraction of EVA/tPA blends with 3 parts per hundred rubber TMPTMA increased from 28% to 86%. The tensile strength of EVA/tPA/TMPTMA-3 (70/30/3) considerably increased up to 172% with a value of 10.01 MPa at 500 kGy due to an increase in cross-linking compared to the EVA/tPA/TAIC-3 (70/30/3) blend. However, the melting temperature and crystallization peak temperature of EVA/tPA blends decreased with increasing irradiation dose. Thermogravimetric analysis demonstrated that the irradiation cross-linking could improve the thermal stability of the EVA/tPA blends. The degradation kinetics of the EVA/tPA blends at elevated temperatures were studied using the Kissinger, Flynn–Wall–Ozawa, and Friedman methods. Irradiation cross-linked EVA/tPA blends exhibited a remarkable improvement in their oil resistance, with the identified improvement being most prominent in the EVA/tPA/TMPTMA-3 blend. [ABSTRACT FROM AUTHOR]

Antistatic packagings are very important for proper transportation and storage of electronic components since these components can be damaged with electric overloads generated through rubbing. Therefore, the purpose of this study was to develop an innovative material for antistatic packaging with a sustainable character. For this, a blend of recycled poly(ethylene terephthalate) (PET), polycarbonate (PC), and polyaniline (PAni) was prepared by melt extrusion. Samples have a final content of 68 wt% of PET, 29 wt% of PC, and 3 wt% of PAni doped with cobalt (PAni-Co). The properties were determined by differential scanning calorimetry, thermogravimetric analysis, tensile testing, electrical resistivity analysis, and Fourier transform infrared spectroscopy. To the best of our knowledge, no previous work studied the incorporation of PAni-Co in PET/PC blend. [ABSTRACT FROM AUTHOR]

Sulfonated poly(ether ether ketone) (sPEEK) membrane is a promising proton-conducting membrane for fuel cell. However, the performance and lifetime of sPEEK membrane depend on the degree of sulfonation (DS). High DS of sPEEK increases the performance, but the mechanical properties could deteriorate progressively which affect its lifetime. Thus, this study investigated the effect of adding polyvinylidene fluoride (PVDF) into high DS (80%) of sPEEK through solution blending method toward its physicochemical properties and morphology structures. The PVDF concentration was varied to 5, 10, 15, and 20 wt% relative to the sPEEK content. The existence of hydrophobic PVDF in 80% sPEEK improved the mechanical properties where the water uptake and swelling degree of membrane decreased, whereas the tensile strength increased. The sPEEK/PVDF 15 exhibited the highest proton conductivity (46.23 mS cm−1) at 80°C. Incorporating PVDF into high DS of sPEEK enhanced the mechanical properties which can be used as a proton-conducting membrane for fuel cell that may improve the performance and prolong the lifetime of the cell. [ABSTRACT FROM AUTHOR]

Electrospun polymer scaffolds are regarded as an ideal tissue engineering scaffold due to similar morphological properties with the native extracellular matrix. Among these, polycaprolactone is widely used to fabricate electrospun fibrous scaffolds due to its excellent biocompatibility, good mechanical properties, and ease of manufacture. However, its low biodegradation rate has a negative influence on its application in tissue engineering scaffold. To address this issue, this study prepared hybrid scaffolds composed of polycaprolactone and polydioxanone (a fast-degrading polyether-ester) via either the blend or co-electrospinning. Subsequently, the structural characteristics, mechanical strength, in vitro/vivo degradation, cellularization, and vascularization of two kinds of hybrid scaffolds were evaluated to decide which method is more suitable for producing tissue engineering scaffolds. The incorporation of polydioxanone increased the mechanical strength of both composite scaffolds. Moreover, co-electrospun scaffolds exhibited improved hydrophilicity compared to blend scaffolds. The results of in vitro and in vivo degradation studies showed that the degradation rate of both composite scaffolds was faster than that of neat polycaprolactone scaffolds due to the incorporated polydioxanone component. Especially in co-electrospun scaffolds, the fast degradation of polydioxanone fiber gave rise to larger pore size, thus leading to faster cellularization and better vascularization compared to blend scaffolds. Therefore, co-electrospinning was demonstrated to be superior to blend electrospinning for the preparation of composite scaffolds. Co-electrospun polycaprolactone–polydioxanone scaffolds may be promising candidates for tissue engineering. [ABSTRACT FROM AUTHOR]

Bispropargyl ether (BPE) of bisphenol-A was prepared. It was blended with 4,4'-bismaleimido diphenyl methane (BMI, 0.5:0.5 mol). The copper sulphate pentahydrate (CuSO4·5H2O) was blended (1% w/w) separately with pure BPE and BPE-BMI blend and the materials were thermally cured. The structural characterization of the materials was done using a Fourier-transform infrared spectrophotometer. The curing behaviour of the materials was investigated using differential scanning calorimetry. The presence of copper salt in BPE shifted the curing temperature to lower temperature region. The presence of copper salt in BPE-BMI blend also decreased the curing onset temperature by approximately 15°C. The thermal property of the polymers was investigated using thermogravimetry. The incorporation of copper salt in BPE-BMI blend led to polymer with increased thermal stability. [ABSTRACT FROM AUTHOR]

A melt blending method was used to prepare acrylonitrile–butadiene–styrene terpolymer and polyethylene terephthalate blends to develop a new blend which can withstand higher temperatures required especially for automotive or home appliance paint curing processes. Blends were characterized by rheological, thermal and mechanical properties. Dimensional stability at 125°C was used to correlate with injection molded part shrinkage. The melt viscosity–composition curves for acrylonitrile–butadiene–styrene/polyethylene terephthalate blends exhibited a trend like the rule of mixtures in which adding acrylonitrile–butadiene–styrene to polyethylene terephthalate improved the processability. Scanning electron microscopy examination revealed different morphologies depending on the composition such as dispersed, co-continuous and phase inverted, which indicated that the binary blends were immiscible and form a two-phase structure. Tensile properties increased with an increase in the polyethylene terephthalate content while the unnotched impact strength reached a maximum at 40 wt.% acrylonitrile–butadiene–styrene content. In differential scanning calorimetry analysis, no partial miscibility was observed from the polyethylene terephthalate phase melting temperature shifts as compared to those of the neat component. Also, acrylonitrile–butadiene–styrene phases acted as nucleating agents due to change in polyethylene terephthalate cold crystallization temperature. In applied post shrinkage measurements by heat aging, we saw that the acrylonitrile–butadiene–styrene dimensional stability was improved with added polyethylene terephthalate. [ABSTRACT FROM AUTHOR]

Self-healing of polymeric material using microcapsules has been developed to repair microcracks within the materials. The self-healing character is reflected from the curing behavior of the material. In this work, curing study of alkyd/epoxy blend was carried out by replacing part of amine hardener with alkyd in the epoxy formulation. The inclusion of alkyd in the epoxy blend resulted in higher degree of curing and higher thermal stability compared to the alkyd-free blend, as evidenced from higher heat of reaction values of differential scanning calorimetry and maximum degradation temperature at 379°C, respectively. Self-healing reaction of epoxy coating as evaluated by Fourier-transform spectroscopy revealed that the 914 cm−1 peak attributed to C–O–C of epoxy has decreased, as the epoxide group was consumed in the reaction. Appearance of a new peak at 1631–1632 cm−1 in the cured coating confirmed that the epoxide has reacted with the carboxylic acid group of alkyd to form ester. [ABSTRACT FROM AUTHOR]

The main aim is to investigate the effect of adding of 5% hydrolyzed poly (ethylene-co-vinyl acetate) (EVAOH), itaconic anhydride (naturally obtained during fermentation of sugars (It.anhydride)), and mercapto-modified ethylene-co-vinyl acetate (EVASH) as compatibilizers on the mechanical properties before and after thermal oxidative aging at 90°C for different time periods up to 7 days, electrical properties, and morphology of ethylene propylene diene monomer/ethylene vinyl acetate (EPDM/EVA) blends of different compositions (75/25, 60/40, 50/50, and 25/75, respectively). Stress at yield, tensile strength, and elongation at break of EPDM/EVA were improved markedly by the addition of 5% compatibilizers (EVAOH, It.anhydride, and EVASH). The micrographs of fractured surfaces obtained from the scanning electron microscope demonstrated further the enhancement of compatibility between EPDM and EVA by the addition of reactive compatibilizers. Further, the blends permittivity ε′ and dielectric loss ε″ have been measured at specific temperatures. The dielectric properties revealed that It.anhydride and EVASH/EPDM/EVA compositions are promising materials for insulation purposes. Finally, aging resistance was improved by the use of compatibilizers. [ABSTRACT FROM AUTHOR]

Typical silicones, including poly(dimethyl siloxane) (PDMS), are amorphous, but poly(tetramethyl-p-silphenylene-siloxane) (PTMPS) containing phenyl rings in the main chain is crystalline. A combination of in-situ X-ray and NMR measurements during heating of PTMPS indicates that the molecular motion of the phenyl rings exhibits remarkable anisotropy even in the molten state, suggesting rigidity of the PTMPS molecules. Therefore, a melt-drawing technique could be successfully applied to PTMPS. The obtained melt-drawn PTMPS membrane is transparent but exhibits an excellent tensile modulus and strength of 1.7 GPa and 20 MPa, which are enough for various industrial applications. Similar introduction of phenyl rings in the main chain is also effective for property development of silicone elastomer. Blend films of PTMPS and silicone elastomer exhibits the characteristic phase separation, depending on the blending compositions. Such blend films give the remarkably higher tensile strength than the original silicone elastomer, due to the crystalline component. [ABSTRACT FROM AUTHOR]

Polycarbonate is an important thermoplastic polymer. Due to its high performance, polycarbonate has a range of engineering applications in construction, automotive, aircraft, data storage, electrical, and telecommunication hardware. However, polycarbonate’s use is limited in advanced applications due to limitations, such as strong hydrophobicity, relatively limited chemical functionality, high melt viscosity, notch sensitivity of mechanical properties, and relative softness. Blending with other thermoplastic polymers improves its physical characteristics. The present review outlines up-to-date developments concerning the design and application of polycarbonate blends. A particular emphasis has been given to establish polycarbonate blends such as:• polycarbonate/polyethylene• polycarbonate/poly(methyl methacrylate)• polycarbonate/poly(vinylchloride)• polycarbonate/ polystyrene• polycarbonate/polyurethane• polycarbonate/polyester• polycarbonate/poly(ɛ-caprolactone).To improve the polycarbonate blend properties, fillers including organic and inorganic reinforcement materials (carbon nanotube, montmorillonite nanoclay, and metal nanoparticle) have also been employed. Polycarbonate blend applications in biomedical, flame retardant, and membrane materials have also been reviewed. To fully exploit the future potential for polycarbonate-based engineering materials, the structure–property relationship and compatibilization mechanisms need to be further explored. [ABSTRACT FROM AUTHOR]

Chitosan, the second most abundant natural fiber after cellulose, is a partially deacetylated polymer of N-acetyl-d-glucosamine. Chitosan is nontoxic, biodegradable, and biocompatible. It also has film-forming properties. Chitosan is blended with many polymeric materials such as: poly(methyl methacrylate), epoxy, polystyrene, polyaniline, polysulfone, and polycarbonate. Chitosan has been used as a filler as well as a fiber material in thermoplastic polymers. However, polymer/chitosan blends may show incompatibility owing to repulsion between polar chitosan functional groups and hydrophobic polymeric matrices. Other limitations associated with the using chitosan in blends are high moisture absorption, low processing temperature, low heat stability, and low flame resistance. Consequently, the fabrication techniques, miscibility, mechanical strength, morphology, and structural features of polymer/chitosan blends have been investigated. Moreover, chitosan addition as a compatibilizer in blended systems has been explored. There are many potential applications for polymer/chitosan in membrane technology, dye removal, packaging materials, drug delivery, tissue engineering, and biochemical relevance. [ABSTRACT FROM AUTHOR]

The market for commercial polymer blends has grown steadily. A good blend should have strong interphases between different parts of the constituted polymers. Lack of strong interphases is a classical problem of the blend industry. Ethylene-propylene-diene monomer rubber (EPDM)/styrene-butadiene rubber (SBR) blends have a very good aging resistance and good compression sets. However, these rubbers are partially miscible. To improve the miscibility of EPDM and SBR in their blends, a Lewis acid, AlCl3, was used to form EPDM–g–SBR copolymer through Friedel–Crafts reactions. The existence of covalent bonds between EPDM and SBR macromolecules was studied by the cure traces of the blends, that is, ΔTorque, Fourier transform infrared spectrums, differential scanning calorimetry (DSC) heat flow curves, thermogravimetric analysis curves, and scanning electron (SEM) micrographs. Subsequently, several blends with EPDM/SBR ratio of 40/60 and with various AlCl3 amounts were prepared and after curing, their mechanical properties were measured and compared. The results showed covalent bonds formed between SBR–EPDM and SBR–SBR macromolecules. An exothermic change in heat flow in the DSC curve was observed around 111.28°C, which can be attributed to the formation of carbocations in Friedel–Crafts reactions. Adding 2 phr AlCl3 had an efficient effect on EPDM–SBR and or SBR–SBR linkages. The mechanical properties of the cured blends, that is, tensile strength were lower when compared with corresponding values for prepared compound with SBR. Excellent compatibility between the two polymers and strong interphases were observed in SEM micrograph of the cured blend with 1 phr AlCl3. [ABSTRACT FROM AUTHOR]

The final color of blend yarns is dependent on the proportion of the various colored fibers used in colored spun yarns. How to scientifically and effectively quantify the relationship between the proportion of different colored fibers and the color of the yarn is a major problem hindering the development of color spinning technology. This paper suggests three methods for analyzing and comparing the color of gray spun yarns. A color match software, Datacolor Match, was used to calculate a recipe simulating the match of dyes; the a predicting formula based on color mixing model of Kubelka-Munk (K-M) double-constant theory for fiber blends was established. Finally, the colored fiber formula based on the known reflectance curve was calculated according to the relationship between the reflectance value of gray spun yarn and proportion of colored fiber present. This work provides an understanding of colored spun yarn fabrication. [ABSTRACT FROM AUTHOR]

Recycling of scrapped tires has become an essential worldwide challenge. The preparation of soft plastics, or thermoplastic elastomers (TPEs), is one of many ways possible for this. Many researchers have prepared TPEs using rubber particles with dimensions 500 μm or more. However, we assume mechanical properties of the TPEs could be improved by using rubber powder with smaller particles. Therefore, we studied the influence of six rubber powder fractions (diameters ranging from 120 to 500 μm) on mechanical properties of TPE samples prepared by blending of ground waste tire rubber (GTR) with lowdensity polyethylene (PE-LD) in the laboratory mixer (Brabender Plastograph). In addition, two adhesion components were applied: ethylene-propylene-diene rubber (EPDM) and a styrene-ethylene/butylene-styrene copolymer (SEBS). The results of tensile tests suggest that the use of smaller particle sizes, together with the adhesion component, can produce TPEs with improved mechanical properties. [ABSTRACT FROM AUTHOR]

Background: The amorphous poly(lactic acid-co-lysine) (PLL) with hydrophilic reactive groups was synthesized by the condensing copolymerization and the blending miscibility of poly(L-lactic acid) (PLLA) and PLL was investigated. Methods: The miscibility of PLLA and PLL was evaluated by analyzing the thermal properties, crystallization behaviors, crystal morphologies and mechanical properties of the PLLA/PLL blends. Results: The results indicated that amorphous PLL changed the crystallization behaviors and thermal properties of PLLA, decreasing the crystallinity of PLLA in the blends. The amorphous PLL molecule chains in PLLA/PLL blends were able to enter into the lamellars of PLLA spherulites and affect the crystallization behaviors of PLLA, resulting in imperfect, spherulite structures of PLLA. The formation of hydrogen bonds between PLLA molecular chains and PLL molecular chains enabled partial compatibility in this blend system. Conclusions: The existence of PLL improved the hydrophility of PLLA/PLL blends, led to a higher content of PLL in the PLLA/PLL blend system, and better hydrophilic properties of the blend system. The PLL was partially miscible with the PLLA, and the PLLA/PLL blend with 10 wt% PLL had improved tensile properties. [ABSTRACT FROM AUTHOR]

Nanotechnology provides the ability to engineer the properties of materials. Nano zinc oxide having particle size ∼50 nm was used with different concentrations to coat the following textiles fabrics: cotton, polyester and blend cotton/ polyester (65/35) using the pad-dry-cure method. The main advantages of these treated samples were their light weight, increasing surface area per unit volume with increasing treatment concentration. The treated samples were characterized through the following measurements: wide angle X-ray diffraction, mechanical tests (tensile strength and elongation percentage) and thermal properties, i.e. diffraction scanning calorimeter. The results indicated that the behavior of the change in crystal parameters for treated cotton samples greatly differed as compared for polyester. The highest intensity and d-spacing in case of treated cotton were observed at zinc oxide concentration 0.25% followed by a decrease. The polyester samples showed gradual increase in intensity by increasing the zinc oxide concentration, while the hybrid structure blend samples followed the mixture behavior rule. The order of improvement in crystalline parameters for the three treated samples was cotton > blend > polyester. Also, the order of improvement in mechanical properties was cotton > polyester > blend; these results may be due to the uniform distribution of ZnO nano-particles on the fabric surface thus the elasticity of the coated fabric increases. [ABSTRACT FROM AUTHOR]

The effect of dispersion of polyaniline on the mechanical, morphology, electrical, and thermal properties of the PS/PMMA blends prepared by solution casting fabrication process was investigated. PS/PMMA (50/50) wt% blend with 3% pluronic and 1% polyaniline gave the best tensile strength in comparison with other blends. So, different concentrations from polyaniline (1, 3, 5, 10, 15, and 20 wt%) were evaluated to obtain the suitable effective concentrations that can be used. The morphology suggests that 3% pluronic and 1% polyaniline can act as mechanical compatibilizer between PS and PMMA as well as a thermodynamic compatibilizer. The thermal stability of the PS/PMMA (50/50 wt%) blend with different concentrations of polyaniline in the presence of 3% pluronic was studied using thermogravimetric analysis, which showed an increase in thermal stability due to the presence of polyaniline. The dielectric investigations reflected an increase in both the permittivity and dielectric loss with increasing the content of polyaniline (PANI), due to interfacial polarization and conductivity effects. In addition the increase in the conductivity of the composites is related to the increase of the conductive paths among the filler. The pathway of conductive filler was easy to form lower percolation threshold of the composite due to better dispersion of PANI. However, composites with low percolation threshold will be favorites for the practical applications with regard to the less deteriorated mechanical properties and processability. [ABSTRACT FROM AUTHOR]

Poly (lactic acid)/maleic-anhydride-grafted-polypropylene (PLA/MAPP) blends were prepared by melt blending method. The effect of MAPP content on the dispersion morphology, thermal properties, and rheological behavior of PLA/MAPP blends was studied. Then PLA/MAPP blends were foamed using supercritical CO2 as physical blowing agent; and the cellular structure, cell size, as well as cell density were investigated. The results showed that of MA reacted with PLA, and thus a small amount of branched polymer would be formed. The branching structure strongly affected the rheological behavior, as well as the thermal properties of PLA. The blending morphology of PLA/MAPP blends also had a significant effect on the cell density of all the samples. The results indicated that homogeneous and finer cellular morphology for PLA/MAPP foams with high expansion ratio could be achieved with a proper content of MAPP in the blends. [ABSTRACT FROM AUTHOR]

In this study, the moisture and thermal transmission properties of cotton/polylactic acid-blended knitted fabrics were studied. Cotton and polylactic acid fibers were blended to produce yarns of 14.7 tex (40 s Ne) with two different blend proportions. The yarns were then knitted into plain jersey structures, followed by scouring and bleaching treatments. The produced fabrics were evaluated for dynamic moisture transport properties using SDL Atlas moisture management tester. The moisture vapor transmission rate of developed fabrics was measured using the dish method, and the thermal properties were measured using KES Thermolabo instrument. Results indicate that blending of polylactic acid fibers with cotton fibers improve the moisture management properties of the resultant fabric. The overall moisture management capability values were found to be better for cotton/polylactic acid fiber 65:35 blended fabric. A marginal improvement was observed only in the case of cotton/polylactic acid fiber 80:20 blended fabric. The moisture vapor transmission and air permeability of blended fabrics were also found to be higher than those of 100% cotton fabric. The thermal conductivity, insulation, and warm–cool feel values of blended fabrics range between 100% cotton and 100% polylactic acid fiber fabrics. This type of fabric is more suitable for use as sportswear and active wear. [ABSTRACT FROM AUTHOR]

Elastomer blends based on fluorosilicone and silicone rubber have been investigated as a seal for aeronautical fuel system. Fluorosilicone seals are widely used as a prospective candidate in the aeronautical fuel system due to its notable resistance to aircraft turbine fuel (ATF) as well as its service in wide temperature applications. However, the FVMQ is relatively inferior in strength and high in cost compared to other ATF resistant elastomers. The drawbacks of FVMQ can be improved by blending with a High Consistent Rubber (HCR) such as vinyl methyl silicone (VMQ), which enhances the strength and reduces the cost. In the present work, an attempt has been made to study the properties and optimization of FVMQ-VMQ blend ratio by varying VMQ content. Blends were prepared in two-roll rubber mixing mill, cured and characterized for rheological, mechanical, physical, ageing and low temperature brittleness resistance. Furthermore, the effects of various aeronautical fluids such as ATF, lubricating and hydraulic oil on blends were also analysed. This paper reports the preface analysis of the properties of FVMQ-VMQ blend as a futuristic seal for the aeronautical fuel system. [ABSTRACT FROM AUTHOR]

A binary blend of acrylonitrile butadiene styrene–high-impact polystyrene (ABS–HIPS 50% wt) was prepared on a twin-screw extruder at 190–210°C. The different properties were then analyzed using tensile strength and impact tests, melt flow index, thermogravimetric analysis, and Fourier transform infrared spectroscopy (FTIR). The analysis of mechanical properties showed a decrease in elongation at break and impact strength. FTIR analysis indicated heterogeneous distribution of the blend in injected pieces and scanning electron microscopic images show heterogeneous distribution of both ABS and HIPS phase. On the other hand, by varying the percentage of styrene–ethylene–butylene–styrene (SEBS) from 10 to 30% wt using a twin-screw extruder at 190–210°C, we have prepared ternary blends of ABS-HIPS-SEBS. The addition of SEBS to the binary system ABS–HIPS allowed us to increase the ductile properties (elongation at break and impact strength), as well as reducing the viscosity. [ABSTRACT FROM AUTHOR]

Poly(lactic acid)/polycarbonate blends were prepared by melt mixing. The transesterification reaction between poly(lactic acid) and polycarbonate was promoted by using tetrabutyl titanate as a catalyst. For poly(lactic acid)/polycarbonate (weight ratio of 75/25) blend with catalyst content up to 0.5 wt%, polycarbonate particles finely dispersed in the poly(lactic acid) matrix and the adhesion between the phases were improved, due to the enhanced compatibility by transesterification reaction. The blends were foamed by using batch-foaming process with CO2 as the blowing agent. Cell density of poly(lactic acid)/polycarbonate blend increased at low-catalyst content, while decreased at high-catalyst content, which was due to the changes of interfacial properties of blend phases through transesterification reaction and crystallinity of polycarbonate component. Cell types of poly(lactic acid)/polycarbonate blends were transferred from submicro-sized and even nanoscale cells to microscale cells by the deceased crystallinity of poly(lactic acid) component, which was caused by the increased degree of transesterification reaction and temperature. The declined viscosity of poly(lactic acid)/polycarbonate blend because of degradation during blend processing led to large cell size and low-cell density. However, the improvement of elasticity and viscosity of poly(lactic acid)/polycarbonate blend by transesterification reaction could decrease the cell size. [ABSTRACT FROM AUTHOR]

Ultrasonically aided extrusion of natural rubber (NR), styrene butadiene rubber (SBR), and NR/SBR blends with ratio of 70/30, 50/50, and 30/70 were carried out at various ultrasonic amplitudes up to 10 μm. A die pressure of NR and NR/SBR blends continuously decreased with increase of ultrasonic amplitude, while that of SBR showed a slight increase with increase in amplitude from 5.0 to 7.5 μm due to a dominant effect of SBR gel formation. Complex dynamic viscosity, minimum and maximum torque of curing curves of NR, SBR, and NR/SBR blends, and cross-link density and gel fraction of their vulcanizates were decreased by the ultrasonic treatment at an amplitude of 10 μm, due to the molecular chain scission. The latter also led to a decrease in the hardness, modulus at a strain of 100%, and abrasion resistance of NR and NR/SBR blends. However, the modulus and abrasion resistance of SBR showed an improvement at amplitude of 7.5 μm, dueto a dominant effect of gel formation. Both the tensile strength and elongation at break of ultrasonically treated NR/SBR blends showed a maximum at amplitude of 5.0 μm, with the modulus at a strain of 100% not being affected. Morphological studies using the phase-contrast optical microscope and atomic force microscopy showed a reduction in the size of rubber phases and a better homogeneity of NR/SBR blend by the ultrasonic treatment at amplitude of 5.0 μm. Accordingly, the increase in both the tensile strength and elongation at break of ultrasonically treated NR/SBR blends at an amplitude of 5.0 μm is mainly ascribed to the lower size of rubber phases and improved uniformity of blend caused by the ultrasonic treatment. [ABSTRACT FROM PUBLISHER]

Poly(vinyl alcohol) (PVA)/pullulan (PULL) blend nanofibres were prepared from their aqueous solutions by electrospinning method. Polymer solutions with different concentrations and blend ratios were used to investigate the effect of polymer concentrations and blend ratios on the morphologies and properties of PVA/PULL nanofibres. At a fixed blend ratio, the total polymer concentrations were also adjusted to find suitable electrospinning condition for preparing uniform and bead-free nanofibres. The as-prepared nanofibres were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Their mechanical properties were also studied by measuring their tensile strength. The results showed that polymer concentrations and blend ratios have direct influence on the morphologies and properties of PVA/PULL nanofibres. 12 wt.% total polymer concentration and higher PVA contents have been found to be favourable for obtaining uniform and bead free PVA/PULL blend nanofibres with improved mechanical and thermal properties. [ABSTRACT FROM AUTHOR]

Presently, for economic and technological concerns, production of blended fibers has attracted the attention of industrial technologists and academic researchers. The importance of blended fibers can be derived from its use in the various fields such as geotextiles, composites, and insulation. In this study, PP/LDPE blended filament yarns with blend ratios of 100/0, 99/1, 97/3, 95/5, 93/7, 90/10 were melt spun, drawn, and textured at temperatures of 110, 120,130,140 and 150° C. Tensile properties (except modulus) of the textured yarns spun from PP/LDPE blends were found to be higher than those of pure PP at most applied texturing temperatures. Crimp properties of samples were improved by increasing the texturing temperature. By increasing the LDPE fraction in samples, especially at 140°C and 150°C, however, lower crimp properties were observed. [ABSTRACT FROM AUTHOR]

This study reports the results of the characterization of cellulose acetate butyrate and polycaprolactone-triol blends in terms of miscibility, swelling capacity, mechanical properties, and inflammatory response in vivo. The cellulose acetate butyrate film was opaque and rigid, with glass transition (Tg) at 134℃ and melting temperature of 156℃. The cellulose acetate butyrate/polycaprolactone-triol films were transparent up to a polycaprolactone-triol content of 60%. Tg of the cellulose acetate butyrate films decreased monotonically as polycaprolactone-triol was added to the blend, thus indicating miscibility. FTIR spectroscopy revealed a decrease in intramolecular hydrogen bonding in polycaprolactone-triol, whereas no hydrogen bonding was observed between cellulose acetate butyrate and –OH from polycaprolactone-triol. The increase in polycaprolactone-triol content in the blend decreased the water uptake. An increase in polycaprolactone-triol content decreased the modulus of elasticity and increased the elongation at break. A cellulose acetate butyrate/polycaprolactone-triol 70/30 blend implanted in rats showed only an acute inflammatory response 7 days after surgery. No change in inflammation mediators was observed. [ABSTRACT FROM AUTHOR]

In this work, we report a melt blend of poly(lactic acid)(PLA)/epoxidized natural rubber (ENR) with liquid natural rubber (LNR). The LNR was synthesized by a photochemical degradation technique and used as a compatibilizer in the PLA/rubber binary blending systems. The PLA/ENR/LNR blends were melt-blended in a Haake internal mixer at 180°C and mixing speed of 50 r. min−1 for 15 min. It was found that the addition of LNR compatibilizer has improved the tensile strength and elongation at break for the compositions of the 40PLA/55ENR/5LNR blend system when compared with a noncompatibilized system (40PLA/55ENR/5NR). The elongation at break for the blend with 5% LNR compatibilizer showed a twofold increment compared with the blend without LNR. The increase in tensile strength and elongation at break were associated with the ability of LNR to promote the uniform dispersion between the natural rubber (NR) and PLA phases as observed in the scanning electron microscopic analysis. Moreover, the differential scanning calorimetric results indicated that the 40PLA/55ENR/5LNR showed the highest degree of crystallinity and thus contributed to improve their mechanical properties. Thermogravimetric analysis showed that two degradation transitions for both compatibilized and noncompatibilized blend systems due to higher degradation temperatures of ENR50 and NR parts. Fourier transform infrared spectroscopic analysis revealed that the PLA/ENR/NR and PLA/ENR/LNR blends were not miscible. [ABSTRACT FROM PUBLISHER]

High melt strength/block polypropylene (HMSPP/PPB) blends and high melt strength/random polypropylene (HMSPP/PPR) blends were prepared by a twin-screw extruder to decrease the high stiffness of polypropylene and to improve its impact strength. Rheological properties of the two blends were investigated using a rotational rheometer . The complex viscosity and storage modulus data at low frequency region indicated that the melt elasticity and melt strength of the blends were affected by varying the content of PPB and PPR in the blends. Moreover, the melt strength of HMSPP/PPR blends was better than that of HMSPP/PPB. The non-isothermal crystallization behaviour of the blends was studied using differential scanning calorimetry with various cooling rates and was analyzed by the Avrami method. It was found that the melt and crystallization temperatures of the blends increased with the ratio of PPR and PPB. PPB also changed the crystallization process of the blends, leading to smaller spherulite size and more spherulites, but PPR only slightly affected the crystal behaviour. [ABSTRACT FROM AUTHOR]

The bisphenol AF/benzyltriphenylphosphonium chloride (BPP) vulcanization system is the most commonly used fluoroelastomer (FPM) vulcanization system. In this article, polyphenol hydroxy acrylic rubber (PHACM) was prepared through a two-step reaction: grafting polymerization and condensation. The properties of FPM/PHACM/acrylic rubber (ACM) blends including vulcanization properties, mechanical properties, aging properties, oil resistance and thermal properties were studied. The results of vulcanization properties show that under the bisphenol AF/BPP vulcanization system, the FPM can achieve covulcanization with PHACM without adding bisphenol AF and get longer scorch time than that of FPM with the same level of bisphenol AF, which means that FPM/PHACM/ACM blends have better processability and curing security. Furthermore, the blends show better mechanical properties and thermal stability. The results of differential scanning calorimeteric analysis show that the FPM and PHACM achieve co-cross-linking and have good compatibility. The glass transition temperature (Tg) of the blends has been reduced to −18.57°C, which is 8.33°C lower than that of pure FPM, when the content of blends is equal to 100/100. The scanning electron microscopy shows that PHACM can improve interfacial adhesion between the FPM and ACM. [ABSTRACT FROM PUBLISHER]

Thermosetting blends of 4-aminophenoxyphthalonitrile (APN)/epoxy resin (ER) were investigated by differential scanning calorimetry (DSC), dynamic rheological analysis and thermogravimetric analysis (TGA). The self-promoted curing behaviors and processing properties of the APN/ER blends and prepolymers were studied by DSC and rheological analysis under dynamic and isothermal conditions. The APN/ER blends and prepolymers exhibited two-step polymerization reactions in the absence of any other curing additives. The APN/ER blends and prepolymers had large processing windows with low melt viscosity, and the size of the processing windows was dependent on the APN monomer concentration. The thermal behaviors of the APN/ER copolymers were studied by TGA. These cured copolymers exhibited decomposition temperatures over 367 oC in either flowing nitrogen or air, and high char yield at 800 oC of 68% under nitrogen atmosphere. Consequently, these studies revealed that the APN/ER system exhibits attractive self-promoted curing reaction, desirable processing feature, excellent thermal and thermal-oxidative stabilities, and high char yields. The APN/ER copolymer will be a good candidate as a matrix for high-performance polymeric materials. [ABSTRACT FROM AUTHOR]

Polycaprolactone/polyethylene glycol (PCL/PEG) blends were prepared by electrostatic spinning. The melting behavior and isothermal, non-isothermal crystallization kinetics were investigated using differential scanning calorimetry (DSC). The results showed the DSC thermograms of blend samples. With increasing PEG content, the position of the crystallization peak shifted to a higher temperature, while the position of the melting peak shifted slightlys. With increasing the heating rates, the position of the melting peak shifted to a higher temperature and the total heat of fusion also gradually increased. Both PCL and PEG could crystallize. By DSC, the PEG and PCL mutually promote to develop a thicker crystal and more perfect crystallite. This effect of promotion may result from the interaction of the molecular chain period of the two polymers. The Avrami equation described the non-isothermal crystallization kinetics of this blend very well. [ABSTRACT FROM AUTHOR]

In this work, isotactic polypropylene (iPP)/high density polyethylene (HDPE) composites filled with carbon black (CB) were prepared by the mild compounding method and the common melt-mixing method. The selective distribution of CB particles in the immiscible iPP/PE blends was determined by the interfacial tensions, but the morphologies of the polyblends strongly depended on the compounding method. The mild compounding method strongly affected PE phases to form triple phase morphology in the composites, which inhibited effective conductivity network formation in the low CB content range. A skin-core structure of the iPP/HDPE/CB composite, prepared by the common melt-mixing process, was present when an effective conductivity network was obtained, and a co-continuous structure of the iPP/HDPE matrix is not necessary. [ABSTRACT FROM AUTHOR]

Proton exchange membranes were prepared by blending sulfonated poly(ether sulfone ether ketone ketone) (SPESEKK) with sulfonated poly(ether sulfone) (SPES). The morphology, tensile strength, proton conductivity and methanol permeability of the blend membranes were investigated. The scanning electron microscope and transmission electron microscope observation indicates the good dispersion of the SPES in SPESEKK polymer matrix. The addition of SPES also enhances the tensile strength of the SPESEKK membrane. The blend membrane shows lower methanol diffusivity and higher proton conductivity with comparison to the pure SPESEKK membrane, ascribing to the inhabitation of the player SPES to methanol permeation and facilitation of the increment of sulfonic acid groups to the proton transport. The SPESEKK/SPES 5 : 5 membrane exhibits an appreciable tensile strength of 52.3 MPa and a reduced methanol permeability of 6.6 × 10−7 cm2 s−1. This SPESEKK/SPES composite membrane shows a potential feasibility as a promising electrolyte for direct methanol fuel cells. [ABSTRACT FROM PUBLISHER]

In this study, polymer membranes were prepared by the melt processing, based on a polycarbonate (PC)/polyamide (PA6) blend, using PC as the matrix phase and PA6 as the dispersed phase. Moreover, nanocomposite membranes were also prepared by the melt processing on the basis ofa PC/PA6/nanoclay blend. The permeability of polymeric membranes was calculated using theoretical models. On the other hand, the permeability of PC/PA6/ nanoclay nanocomposite membranes was measured by an isochoric method. Then the results were compared. The cross-sectional morphology of the prepared membranes was observed by SEM. The surface roughness of the samples was measured by AFM. Results showed that the levels of porosity and surface roughness of membranes decreased with increase in PA6 concentration. According to the results, an increase in permeability is observed, with increase in PA6 concentration, and PC/PA6 benefit blend for prepared membrane to increase selectivity and performance. With the addition of nanoclay to the blend, the degree of porosity and the free volume decreased, and the roughness in membrane also decreased; in fact, a decrease in permeability is observed when nanoclays are added. [ABSTRACT FROM AUTHOR]

The blends of polycarbonate (PC) and Poly (aryl ether ketone) containing 1,4-Naphthalene (NA-PAEK) were prepared by melt mixing in a Brabender-like apparatus. The specimens for measurements were made by compression molding under pressure and then were water-quenched at room temperature. The miscibility behavior of PC with NA-PAEK was examined using differential scanning calorimeter (DSC), scanning electron microscope (SEM), and density. [ABSTRACT FROM AUTHOR]

For the case of the ternary blend system of polycarbonate (PC), polyethersulfone (PES) and a multi-block random copolymer of PES and PC, it was found that the interfacial adhesion was enhanced, the size of the dispersed phase was reduced and PES and PC formed an interlocking structure with the multi-block random copolymer. This suggests that the addition of the compatibilizer may have improved the miscibility between PES and PC, and yielded an improvement of the mechanical properties of the blends. The compatibility behavior of PES with PC was examined using differential scanning calorimetry, scanning electron microscopy, and dynamic mechanical analysis. [ABSTRACT FROM AUTHOR]

In this work, preparation and characterization of HDPE/PA6 foam blends is presented. Using a chemical blowing agent based on azodicarbonamide, foams were produced via extrusion using different concentrations of the dispersed phase PA6. Due to very different thermal and rheological properties of the polymers, good cellular structures could only be obtained by a careful selection of the temperature profile and feeding strategy of the materials. Furthermore, the use of a coupling agent was also found necessary to stabilize the blend before foaming. The final foam morphology was controlled by post-extrusion conditions and the results are discussed in terms of deformation and dimensions of foam cells and dispersed phase particles. The tensile and impact properties of the resulting foams are also reported. [ABSTRACT FROM PUBLISHER]

The blends of fluororubber (FKM) and silicone rubber (MVQ) were prepared by the incorporation of fumed silica at different contents using 2,2,2-trifluoroethyl methacrylate grafted silicone rubber (MVQ-g-TFEMA) as a compatibilizer. The effect of the compatibilizer content on the curing characteristics, crosslink density, mechanical properties, heat aging properties, oil resistance, and low temperature properties were investigated. The effect of fumed silica content on the mechanical properties of FKM/MVQ blends in the presence of MVQ-g-TFEMA was also studied. The dynamic mechanical analysis indicates that MVQ-g-TFEMA acts as a compatibilizer in the FKM/MVQ blends. The mechanical properties and oil resistance of FKM/MVQ blends increase with the increasing of MVQ-g-TFEMA content up to 6 phr and the heat aging properties increase with the addition of the compatibilizer. Rubber—filler interactions in the blends increase with the increasing of the compatibilizer content. Rubber—filler interaction studies show that the presence of MVQ-g-TFEMA enhances the interfacial interaction of fumed silica and rubber matrix. The tear strength and hardness increase by the incorporation of fumed silica, and the tensile strength and elongation at break increase with the addition of the fumed silica up to 30 phr in the presence of 6 phr MVQ-g-TFEMA. [ABSTRACT FROM PUBLISHER]

Foaming of blend systems is a promising approach to develop cellular materials with a set of desired properties. However, foaming of blend systems is not only a chance but also a challenge, as different polymers have to be foamed at the same foaming conditions. The best conditions during foaming are individual to each polymer and influence the obtained cellular structure. In immiscible polymer blends like poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) (SAN) the differences in glass-transition temperature (Tg) and viscosity are vast and can inhibit the foaming of the blend system. In order to minimize the above-mentioned difference in Tg and viscosity, one approach is to choose a blowing agent, which shows a selective solubility in one polymer phase, working as a selective plasticizer. The aim of the present study is to evaluate systematically the foaming behavior of immiscible PPE/SAN blend systems using ethanol and n-pentane as blowing agents. Mass uptake of ethanol and n-pentane in the PPE/SAN-blends as function of the blend composition is measured, offering a selective solubility of ethanol in SAN, while n-pentane shows a high affinity to PPE. The plasticizing effect on the blend phases PPE and SAN is theoretically estimated using the Chow-equation and the WLF-equation. After foaming the blowing agent saturated blend samples in an oil-bath at different temperatures, the density reduction and the cellular structures are analyzed and correlated to the blend morphology, the blowing agent solubility in the blend phase, the rheological properties and the glass transition temperature of the nonsaturated and saturated blend phases. [ABSTRACT FROM AUTHOR]

The fluororubber/silicone rubber blends were prepared by using fluororubber grafted by γ-methacryloxypropyltrimethoxysliane as a compatibilizer. Fourier transform infrared Spectra revealed that γ-methacryloxypropyltrimethoxysliane has been grafted onto fluororubber backbone. The effect of the compatibilizer content on curing characteristics, stress-strain behavior, mechanical properties, heat aging properties, and oil resistance was investigated. The results showed that the mechanical properties and oil resistance of the blends were improved with increasing of the compatibilizer up to 11.8 wt%. The compatibility of fluororubber and silicone rubber phase was characterized by dynamic mechanical analysis. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) was synthesized chemically and doped with camphor sulfonic acid. New PANI/formvar blend films were prepared using solution blending. These blend films were characterized by UV-visible, Fourier transform infrared spectra and scanning electron microscopy to investigate their optical, structural and morphological properties. It was found that the percolation threshold of these blend films is 4.4 wt.% of PANI. The dc and ac conductivities of these blend films were measured at a temperature range from 70 to 300 K in the frequency range of 10 kHz-1 MHz. The temperature dependence of the dc conductivity of the PANI/formvar blend films followed the three-dimensional variable range hopping. Temperature variation of frequency exponents in this blend suggests that ac conduction is attributed to be correlated to barrier hopping. [ABSTRACT FROM AUTHOR]

Glycerol and formamide are used as plasticizers to prepare dry thermoplastic starch (DTPS) in a single-screw extruder. Glycerol/formamide-water plasticized starch (TPS) is also studied as a standard. Scanning electron microscopy reveals that more residual granules exist in glycerol-plasticized dry starch than in other blends. After the removal of water, DTPS becomes rigid and fragile. Increasing the formamide content results in a dramatic increase in the elongation of DTPS, and it maintains a high tensile strength. Dynamic mechanical thermal analysis demonstrates that formamide can decrease the glass transition temperature (Tg) of TPS and replace water to form formamide-starch mixtures in DTPS. Thermogravimetric analysis shows that destructurization of the polysaccharide chain is accelerated after removal of water, but it is alleviated by increasing the formamide content. It is also shown using Fourier transform infrared spectroscopy that formamide can form stronger hydrogen-bond interactions with starch than glycerol. At the same time, X-ray diffractometry shows that starch is plasticized more completely both in TPS and DTPS with a high formamide content. Finally, rheological study shows that formamide can decrease the shear viscosity and improve the fluidity of TPS and DTPS. [ABSTRACT FROM AUTHOR]

A novel method for synthesis of sulfonated ionomer of (styrenebutadiene- styrene) triblock copolymer (SBS) is developed. SBS is first epoxidized by performic acid formed in situ, followed by ring-opening reaction with an aqueous solution of NaHSO3. The optimum conditions for ring-opening reaction of the epoxidized SBS with aqueous solution of NaHSO3 and some properties of the ionomer are studied. It has been found that during the ring-opening reaction phase transfer catalyst, ring-opening catalyst, and a pH regulator are necessary to raise the conversion of epoxy groups to ionic groups. The product is characterized with FTIR spectrophotometry and transmission electron microscopy (TEM) to be the sulfonated ionomer with ionic domains about 5 nm in diameter. With increasing ionic groups, the water absorbency of the ionomer and the dilute solution viscosity of the ionomer increase, whereas the oil absorbency decreases. The ionomer behaves as thermoplastic elastomer in the presence of zinc stearate as ionic plasticizer. The tensile strength and ultimate elongation of the sodium ionomers are higher than those of the original SBS and both increase with zinc stearate below 10wt% and with ionic group content up to about 1 mmol]g. When the ionomer is blended with crystalline polypropylene, a synergistic effect occurs with respect to the tensile strength. The ionomer can act as a compatibilizer for blending equal weight of SBS and off-resistant chlorohydrin rubber. In the presence of 3% ionomer, the blend exhibits much better mechanical properties and solvent resistance than the blend without the ionomer. The blend of equal weight of SBS and CHR compatibilized by the ionomer behaves as an oil resistant thermoplastic elastomer. Scanning electron micrographs of the blends with or without the ionomer indicate the increased compatibility between the two components in the presence of the ionomer. [ABSTRACT FROM AUTHOR]

Blends of low density polyethylene (LDPE) and polyamide-6 (PA6) are produced via blown film extrusion to study the effect of freeze-line position and stretching force on blend morphology. An experimental setup is designed to measure the stretching force as a function of draw ratio (DR) and freeze-line position for 4, 6, and 10 wt% PA6 in LDPE. Numerical simulations of the non-isothermal and viscoelastic process are in good agreement with the experimental data of film dimensions. However, as reported many times in the literature, the calculated stretching force is underestimated and can be predicted more precisely by using a simple correction factor. The results also show that the dispersed phase deformation increases with DR and decreases with freeze-line height. [ABSTRACT FROM AUTHOR]

Well-defined poly(2,6-dimethyl-4,4′-phenylene oxide)-g-poly(styrenesulfonic acid) (PPO-g-PSSA) graft copolymer was synthesized via living radical polymerization. For the graft copolymer, poly(2,6-dimethylphenylene oxide) (PPO) was brominated first, and the brominated PPO (PPO-Br) was used as a macroinitiator in the atom transfer radical polymerization (ATRP) of styrenesulfonic acid sodium salt. The number of grafts per PPO chain and the molecular weight of the graft were controlled by adjusting the degree of bromination, and conversion in ATRP, respectively. The graft copolymers obtained were transformed into proton exchange membranes for direct methanol fuel cell (DMFC) application. The performance of the membranes was measured in terms of water uptake, proton conductivity, methanol permeability, and thermal stability. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with PSSA block content. Very low methanol permeability and good proton conductivity were observed by adjusting grafting frequency and PSSA block content. [ABSTRACT FROM PUBLISHER]