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Neat Polymer (neat + polymer)
Selected AbstractsApproaches to polymer selection for mascara formulationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2010Y. Loginova J. Cosmet. Sci., 60, 125,133 (March/April 2009) Synopsis The use of hair-care and hair-styling polymers in mascara formulation is well known. This paper introduces pre-formulative evaluation of film formers which are intended to be applied on eyelashes for mascara development to screen film formers more effectively. The film-forming characteristics of randomly selected hairstyling polymers were evaluated under the influence of pH, temperature, surfactant, and pigment dispersion. The selected polymers included acrylics, polyurethanes, and a pyrrolidone, all of which are used throughout the hair-care and mascara industries. An Erichsen Model 299/300 Pendulum Damping Tester was used to determine film hardness. In analyzing samples by the effect of temperature, the hardest neat polymer, a styrene-acrylate, softened 30% after heating. For most of the other polymers, the hardness was slightly lower compared to the neat polymer. The addition of pigment did not significantly influence the hardness of one acrylic copolymer and a urethane dispersion, but most of the other polymers exhibited a reduction in film hardness. Various hardnesses were observed with different surfactants and different pH's. [source] Synthesis and Study of CdS Nanoparticle-Doped Poly(1,4-dihexyloxybenzene)MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 4 2008Gouri Sankar Paul Abstract A simple, economical and high yielding method to prepare poly(1,4-dihexyloxybenzene), an alkylated derivative of poly(para -phenylene) (PPP), is reported. We further prepared a composite of poly(1,4-dihexyloxybenzene) and CdS nanoparticles and studied their structural, optical, stability and transport properties. It was observed that the conductivity of poly(1,4-dihexyloxybenzene) increased by several orders of magnitude when doped with CdS nanoparticles. Similarly, CdS nanoparticle-doped PPP showed higher thermal stability, when compared to the neat polymer. As these composites could be processed in the same way as organic polymers, they would find applications in many low-cost optoelectronic devices. [source] Effect of processing technique on the dispersion of carbon nanotubes within polypropylene carbon nanotube-composites and its effect on their mechanical propertiesPOLYMER COMPOSITES, Issue 5 2010Amal M.K. Esawi Carbon nanotube-reinforced polymer composites are being investigated as promising new materials having enhanced physical and mechanical properties. With regards to mechanical behavior, the enhancements reported thus far by researchers are lower than the theoretical predictions. One of the key requirements to attaining enhanced behavior is a uniform dispersion of the nanotubes within the polymer matrix. Although solvent mixing has been used extensively, there are concerns that any remaining solvent within the composite may degrade its mechanical properties. In this work, a comparison is carried out between solvent and "solvent-free" dry mixing for dispersing multiwall carbon nanotubes in polypropylene before further melt mixing by extrusion. Various weight fractions of carbon nanotubes (CNTs) are added to the polymer and their effect on the mechanical properties of the resulting composites is investigated. Enhancements in yield strength, hardness, and Young's modulus when compared with the neat polymer, processed under similar conditions, are observed. Differences in mechanical properties and strain as a function of the processing technique (solvent or dry) are also clearly noted. In addition, different trends of enhancement of mechanical properties for the solvent and dry-mixed extrudates are observed. Dry mixing produces composites with the highest yield strength, hardness, and modulus at 0.5 wt% CNT, whereas solvent mixing produces the highest mechanical properties at CNT contents of 1 wt%. It is believed that this difference is primarily dependent on the dispersion of CNTs within the polymer matrix which is influenced by the processing technique. Field emission scanning electron microscopy analysis shows the presence of clusters in large wt% CNT samples produced by dry mixing. Samples produced by solvent mixing are found to contain homogeneously distributed CNTs at all CNT wt fractions. CNT pull-out is observed and may explain the limited enhancement in mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Kaolin,epoxy-based nanocomposites: A complementary study of the epoxy curing by FTIR and fluorescencePOLYMER COMPOSITES, Issue 5 2010P.D. Castrillo This work is focused on the study of the effect exerted by the presence of kaolin on the cure reaction of an epoxy-based polymer, discussing the influence of different kaolin pretreatments. During the last few years, the interest on polymer matrix nanocomposite materials has sharply increased because generally they show improved properties when compared with those of the neat polymer (without filler). Among this sort of materials, polymer clay nanocomposites have been widely studied. However, there are not many works about kaolin-based composites. Although several techniques have been used to monitor the cure process in epoxy-based composites such as Fourier transform infrared spectroscopy (FTIR) or differential scanning calorimetry, only the use of the fluorescent response from a fluorophore seems to be adequate to monitor the reaction exactly at the interfaces at a molecular scale. In this work, FTIR and fluorimetry were used to monitor the cure reaction of the different composite systems at different curing temperatures. The analysis of FTIR experiments revealed that the presence of the reinforcement clay affects the extent of the cure reaction depending on the nature of its surface. On the other hand, the use of a fluorescent molecule chemically bonded to the reinforcement allows studying the curing exactly at the interface. Finally, with the collected data, a kinetic analysis was done and the results obtained were compared in terms of the technique used and the information source (interface or bulk). At the interface, the activation energy for the epoxy reaction is lower than that carried out in the bulk indicating that the reaction at the interface proceeds via a particular mechanism for which the reaction is favored. It seems that a higher amount of hydroxyl groups is capable of catalyzing the cure reaction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Mechanical properties of Al2O3/polymethylmethacrylate nanocompositesPOLYMER COMPOSITES, Issue 6 2002Benjamin J. Ash Alumina/polymethylmethacrylate (PMMA) nanocomposites were produced by incorporating alumina nanoparticles, synthesized using the forced gas condensation method, into methylmethacrylate. The particles were dispersed using sonication and the composites were polymerized using free radical polymerization. At an optimum weight percent, the resulting nanocomposites showed, on average, a 600% increase in the strain-to-failure and the appearance of a well-defined yield point when tested in uniaxial tension. Concurrently, the glass transition temperature (Tg) of the nanocomposites dropped by as much as 25°C, while the ultimate strength and the Young's modulus decreased by 20% and 15%, respectively. For comparison, composites containing micron size alumina particles were synthesized and displayed neither phenomenon. Solid-state deuterium NMR results showed enhanced chain mobility at room temperature in the nanocomposites and corroborate the observed Tg depression indicating considerable main chain motion at temperatures well below those observed in the neat polymer. A hypothesis is presented to relate the thermal and mechanical behavior observed in the composites to the higher chain mobility and Tg depression seen in recent ultrathin polymer film research. [source] Measurement and prediction of LDPE/CO2 solution viscosityPOLYMER ENGINEERING & SCIENCE, Issue 11 2002Surat Areerat When CO2 is dissolved into a polymer, the viscosity of the polymer is drastically reduced. In this paper, the melt viscosities of low-density polyethylene (LDPE)/supercritical CO2 solutions were measured with a capillary rheometer equipped at a foaming extruder, where CO2 was injected into a middle of its barrel and dissolved into the molten LDPE. The viscosity measurements were performed by varying the content of CO2 in the range of 0 to 5.0 wt% and temperature in the range of 150°C to 175°C, while monitoring the dissolved CO2 concentration on-line by Near Infrared spectroscopy. Pressures in the capillary tube were maintained higher than an equilibrium saturation pressure so as to prevent foaming in the tube and to realize single-phase polymer/CO2 solutions. By measuring the pressure drop and flow rate of polymer running through the tube, the melt viscosities were calculated. The experimental results indicated that the viscosity of LDPE/CO2 solution was reduced to 30% of the neat polymer by dissolving CO2 up to 5.0 wt% at temperature 150°C. A mathematical model was proposed to predict viscosity reduction owing to CO2 dissolution. The model was developed by combining the Cross-Carreau model with Doolittle's equation in terms of the free volume concept. With the Sanchez-Lacombe equation of state and the solubility data measured by a magnetic suspension balance, the free volume fractions of LDPE/CO2 solutions were calculated to accommodate the effects of temperature, pressure and CO2 content. The developed model can successfully predict the viscosity of LDPE/CO2 solutions from PVT data of the neat polymer and CO2 solubility data. [source] Thermoplastic silicone elastomer lubricant in extrusion of polypropylene wood flour compositesADVANCES IN POLYMER TECHNOLOGY, Issue 2 2007Velichko Hristov Abstract A possibility of using a thermoplastic silicone elastomer (TPSE) for reduction of surface defects in the extrusion of wood-filled metallocene polypropylene (mPP) has been investigated in this work. A capillary rheometer and a single-screw extruder have been utilized to study the effect of the additive on the extrudate distortions. Maleated syndiotactic metallocene polypropylene was also used as an adhesion promoter in mPP/wood flour composites. At loadings of 50 wt% wood flour in the mPP, the extrudates come out of the die with significant tearing and surface roughness. The surface rupture mechanism is similar to that of sharkskin in neat polymers; however, the defect is much more exaggerated in the case of wood fiber-filled composites. It was found that TPSE at low concentrations (1 wt%) was able to reduce or even completely eliminate extrudate surface tearing. Increasing the extrusion speed yielded better results. Addition of a coupling agent also provides improvement in the extrudate appearance. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:100,108, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20090 [source] Gas sorption in polymers, molecular sieves, and mixed matrix membranesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Theodore T. Moore Abstract Gas sorption has been an underutilized technique for characterizing organic,inorganic hybrid (mixed matrix) membranes. Sorption in these membranes, which are composed of rigid inorganic domains, such as zeolites, dispersed in a polymer matrix, should be approximately additive. Sorption in the neat polymers and zeolites were first measured to demonstrate that sorption in mixed matrix membranes is approximately additive in the absence of other effects. Sorption in mixed matrix membranes was demonstrated to be additive. This extends to cases where sorption in one or both phases of the mixed matrix membrane is affected by an outside contaminant. For example, zeolite 4A is extremely hydrophilic and easily affected by contaminants from processing or from the test gases. Zeolite 4A encapsulated within a polymer matrix can still be affected by these same components, and this causes sorption lower than predicted based on that in unaffected polymers and sieves. This sorption analysis has proven to be very important in understanding the permeabilities and selectivities of mixed matrix membranes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4053,4059, 2007 [source] Effect of pressure on the luminescence of a series of methoxy phenylacetylene dendrimers neat and in dilute solution in solid poly(tert -butyl methacrylate)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2001A. Zhu Abstract The effect of pressure up to 60 kbar was measured on the luminescence peak location and efficiency for a series of methoxy phenylacetylene dendrimers (MeO). Dendrimers MeO-3, MeO-7, MeO-15, MeO-31, MeO-63, and MeO-127 were studied as neat polymers. MeO-3, MeO-15, MeO-63, and MeO-127 were also investigated in dilute solutions in poly(tert -butyl methacrylate). According to measurements of the dilute solutions, there is a charge-transfer (CT) state that, for the smaller dendrimers, lies well above the ,* state; for the larger dendrimers, it is the emitting state at 1 atm. With increasing pressure, the intramolecular CT state is rapidly stabilized, so that at high pressure the emission is from this state for all dendrimers. For the neat polymers, there is an initial redshift that reverses direction at a pressure that is higher for smaller dendrimers. This reversal is attributed to intermolecular CT. There may be changes in the molecular geometry and/or relative orientation of adjacent dendrimers that tend to stabilize the intermolecular CT in the solid state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2859,2865, 2001 [source] The effect of interface characteristics on the static and dynamic mechanical properties of three-component polymer alloysPOLYMER COMPOSITES, Issue 3 2002I. Fisher The effect of interfacial characteristics on the structure-property relationships of ternary polymer alloys and blends comprising polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH) and glass beads (GB) or fibers (GF) was investigated. The systems studied were based on a binary PP/EVOH immiscible blend, representing a blend of a semi-crystalline apolar polymer with a semi-crystalline highly polar copolymer. The ternary systems studied consisted of filler particles encapsulated by EVOH, with some of the minor EVOH component separately dispersed within the PP matrix. Modification of the interfacial properties was done using silane coupling agents for the EVOH/glass interface and compatibilization using a maleic anhydride grafted PP (MA-g-PP) for the PP/EVOH interface. Both glass fillers increased the dynamic modulus and decreased the damping of the neat polymers and of their binary blends, especially in the rubbery region. GF has a more profound effect on both the modulus and the damping. Glass surface treatments and compatibilization have only a marginal effect on the dynamic mechanical behavior of the ternary blends. Yet, compatibilization shifted the polymers' TgS to higher temperatures. Both glass fillers increased the elastic modulus of the binary blends, where GF performed better than GB as a reinforcing agent. GF slightly increased the strength of the binary blends while, GB reduced it. Both fillers reduced the ductility of the binary blends. The blends' mechanical properties were related to the morphology and their components' crystallinity. The compatibilizer increases both stiffness and strength and reduces deformability. [source] Dynamic mechanical properties and morphology of poly(benzyl methacrylate)/epoxy thermoset blendsPOLYMER ENGINEERING & SCIENCE, Issue 9 2010Margarita G. Prolongo Poly(benzyl methacrylate) (PBzMA)/epoxy thermoset blends of composition 5 to 25 wt% of PBzMA were prepared curing with 4,4,diaminodiphenylmethane (DDM), to study the influence of composition on the morphology and dynamic-mechanical properties of the blends. The cured blends are phase separated in PBzMA-rich phase and epoxy rich-phase. As the PBzMA content increases, the morphology evolves from nodular, to combined and to totally inverted. The analysis of the ,-mechanical relaxations indicates that the glass transition temperatures (Tg) of PBzMA and of epoxy in the blends are different from the neat polymers, this is related to a noncomplete phase separation on curing. The profiles of the loss modulus-temperature curves are correlated with the change in morphology that appears increasing the PBzMA content. The storage modulus-temperature curves are highly dependent on the morphology of the samples. The storage modulus-composition dependence is predicted using several models for two phase composites. POLYM. ENG. SCI., 50:1820,1830, 2010. © 2010 Society of Plastics Engineers [source] | ||||||||||