Search results for "Polymer blend"
showing 10 items of 219 documents
Evolution of the morphology and characterzation of compatibilized PBT/EVA blends prepared by reactive extrusion
2006
In this work, the possibility of preparing compatibilized blends of poly(butylene terephthalate) (PBT) and an ethylene vinyl acetate (EVA) copolymer by reactive extrusion in the presence of an ethylene acrylic acid copolymer (EAA) and a bisoxazoline compound (PBO) as compatibilization promoters has been studied. In addition, the evolution of the morphology of the blends under different annealing conditions in the presence and absence of the compatibilizing promoters has been studied. Binary blends of PBT and EVA showed behavior typical of incompatible blends with a gross morphology and bad mechanical performance. The situation was however different for ternary PBT/EVA/EAA and especially for…
Effect of the additive level and of the processing temperature on the re-building of post consumer pipes from polyethylene blends
2007
Abstract One of the main shortcomings of the mechanical recycling is that the properties of the secondary materials are generally sensibly inferior with respect to the virgin ones. This feature implies, for sure, that they cannot be used for the same technological application but also other uses of the secondary material are impossible. The aim of this work is to study the re-building of recycled post-consumer pipes, made of a blend of different polyethylenes, by re-processing in the presence of a nitroxyl compound as radical generator. The processing temperature and the additive concentration have been varied in order to study the effect of these parameters on the final properties. The mec…
Physical properties of virgin-recycled ABS blends: Effect of post-consumer content and of reprocessing cycles
2012
Abstract Virgin/post-consumer ABS (pc-ABS) blends were re-processed and re-formed up to three times. The effect of pc-ABS content and of reprocessing cycles on the physical properties of the prepared blends was evaluated by mechanical tests (tensile, flexural and impact tests) and by rheological and thermo-mechanical measurements. The processability of pc-ABS blends was not substantially different by that of virgin ABS up to two recycling steps even if the third one induced a slightly decrease of viscosity, more remarkable on increasing the pc-ABS content. The mechanical and thermo-mechanical properties of the samples worsened on increasing the level of pc-ABS and after each reprocessing op…
Using Janus Nanoparticles To Trap Polymer Blend Morphologies during Solvent-Evaporation-Induced Demixing
2015
Using ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and Janus particles (JPs) with symmetric PS and PMMA hemispheres, we demonstrate the stabilization of dispersed and bicontinuous phase-separated morphologies by the interfacial adsorption of Janus particles during demixing upon solvent removal. The resulting blend morphology could be varied by changing the blend composition and JP loading. Increasing particle loading decreased the size of phase-separated domains, while altering the mixing ratio of the PS/PMMA homopolymers produced morphologies ranging from PMMA droplets in a PS matrix to PS droplets in a PMMA matrix. Notably, bicontinuous morphologies were obtained …
The glass transition of mixtures of polystyrene with alkyl-terminated oligostyrene — experimental evidence for microphase separation in a polymer ble…
1995
Mixtures of high molecular weight polystyrene (P n = 961.5 ; T g = 373 K) and sec-butyl-terminated oligostyrene (P n = 10.6 ; T g = 302 K) show a dependence of the glass transition on the composition (i.e., number-average molecular weight) which cannot be described by the classic equations of Fox & Flory or Kanig & Ueberreiter. Addition of small amounts of the oligostyrene strongly decreases the glass transition, and above an oligomer content of 40 wt.-% the glass transition remains constant within experimental error. This behavior can be attributed to the unfavorable interactions between the alkyl-terminated oligomer and the high molecular weight PS. As a result the oligomer is a bad solve…
Influence of the Copolymer Content on the Miscibility, Phase Behaviour and Morphology of a DGEBA/Polystyrene/Styrene-co-Maleic Anhydride Ternary Blend
2009
The miscibility, phase behaviour and morphology of ternary systems, formed by a DGEBA-based epoxy resin, polystyrene (PS) and styrene-co-maleic anhydride (SMA) copolymers have been investigated through phase diagrams. The analysis has been done in the absence and in the presence of 4,4'-methylene bis(2,6-diethyl aniline) (MDEA) as curing agent. In both cases, the influence of the copolymer content on blend compatibility, has been discussed. The results show that miscibility is enhanced by the presence of SMA copolymer in the blend and as the MA content in the copolymer is increased (from 7 to 14wt.-%), due to specific H-bonding interactions between the H-donor hydroxyl groups on the epoxy r…
Rheology of a Lower Critical Solution Temperature Binary Polymer Blend in the Homogeneous, Phase-Separated, and Transitional Regimes
1996
Small amplitude oscillatory shear rheology is employed in order to investigate the linear viscoelastic behavior of the lower critical solution temperature blend polystyrene/poly(vinyl methyl ether), PS/PVME, as a function of temperature and composition. At low temperatures, where the mixture is homogeneous, the dependence of the zero shear viscosity (η0) on concentration is measured and is well-described by means of a new mixing rule, based on surface fractions instead of volume fractions. Shift factors from time-temperature superposition (TTS) exhibit a Williams−Landel−Ferry (WLF) behavior. As the macrophase separation temperature is approached (the phase diagram being established by turbi…
Degradation of polymer blends: A brief review
2017
Abstract The usefulness of any material, including polymer blends, depends on its degradability and durability. The blend composition can significantly affect the degradative behavior of a polymer blend and can differ from the degradation routes of the pure components since the interactions among different species in the blends during degradation, and among the degradation products, can occur. These reactions can lead either to an acceleration of the degradation rate or to a stabilizing effect in comparison with the pure components. Thus, the additive rule cannot be often applied in case of degradation of polymer blends and, therefore, it is difficult to predict the degradative behavior of …
Mechanical Properties of High-Density Polyethylene/Chlorinated Polyethylene Blends
2004
Results of experimental investigation of mechanical properties of high-density polyethylene (HDPE)/chlorinated polyethylene (CPE) blends in tension are reported. The specimens of pure HDPE, CPE, and nine types of HDPE/CPE blends, with different component ratios at 10 wt.% intervals, are examined. The features of the stress-strain curves obtained are discussed. Data on the influence of blend composition on the elastic modulus, yield stress, breaking stress, and ultimate elongation are obtained. The results of investigations into the creep behavior are also presented. It is found that the creep compliance obeys the power law of creep with coefficients depending on blend composition.
Thermomechanical properties of radiation-modified blends of polyethylene with liquid crystalline copolyester
1999
The results of investigation of gamma irradiated blends of high-density polyethylene (PE) with thermotropic polymer liquid crystal (PLC) are presented. The PLC used was a copolyester of 40% poly(ethylene terephthalate) with 60% p-(hydroxy-benzoic acid). The PLC content in the blends was 0, 5, and 10 wt%. The constituents were blended with the use of a single screw extruder. The specimens were prepared by compression molding. The irradiation of the samples was performed by a Co 60 γ-radiation source in inert atmosphere (argon) up to absorbed relatively low doses (up to 200 kGy: 1 Mrad = 10 kGy). The morphological, thermal, and mechanical properties were investigated for irradiated and unirra…