Search results for "Plastics"
showing 10 items of 2724 documents
Electrospun rubber/thermoplastic hybrid nanofibers for localized toughening effects in epoxy resins
2020
Synthetic rubber/thermoplastic blends were electrospun from their solutions. The rubber was a solid acrylonitrile/butadiene/acrylic acid copolymer and the thermoplastic was polyacrylonitrile. The aims of this study were to identify suitable systems and processing conditions for obtaining rubber-based electrospun nanofibers, to investigate the ability of an epoxy resin system to impregnate and swell selected hybrid rubber/thermoplastic mats, and to assess the impact of the nanofibers on the resin morphology and curing behavior. In particular, electrospinning trials were carried out varying the composition of the feed solution and process parameters, such as the applied voltage, the flow rate…
Deposition and production of highly reproducible hybrid Cu[(tBu)4Pc]-polystyrene thin layers via spin casting
2012
This study focuses on the determination of a protocol for the production of a hybrid material composed of a polymer and a macrocyclic complex, namely polystyrene and a tetra-tert-butyl-copper phthalocyanine (Cu[(tBu)4Pc]), in order to obtain a layer thickness of about 100 nm and a controlled porosity in a highly reproducible way. Several methods were implemented and their reproducibility was evaluated through elements of characterization such as optical microscopy, atomic force microscopy and scanning electron microscopy. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers
On the Improvement of the Processability of UHMW-HDPE by Adding a Liquid Crystalline Polymer and a Fluoroelastomer
2001
Ultra-high molecular weight polyethylene possesses many interesting properties but a very bad processability. This material is not usually processed in conventional devices but only by compression moulding and RAM extrusion. Low molecular weight polyethylene can be used to improve the processability. In this work small amounts of a fluoroelastomer and of a liquid crystalline polymer have been used as processing aids to improve the extrudability of this polymer. In fact, the die pressure decreases whereas the output flow rate slightly increases with increasing concentration of the processing aids. Solution viscosity data shows that reduction of the mechanical stress during extrusion decrease…
Rapeseed oil-based rigid polyisocyanurate foams modified with nanoparticles of various type
2014
Polyisocyanurate foams have been developed using a polyol system partially derived from rapeseed oil (RO). The effect of nanofillers with iso-dimensional geometry (zinc oxide), nanofibers (carbon nanotubes), and nanoplatelets (organically modified montmorillonite) on stiffness and strength of the foams has been studied. It was demonstrated that the tensile properties of the filled foams are enhanced by roughly the same proportion as the stiffness and strength of monolithic filled polymers.
On the Use of the Nanoindentation Unloading Curve to Measure the Young's Modulus of Polymers on a Nanometer Scale
2005
Summary: The nanoindentation test is a fundamental tool to assess the link between morphology and mechanical properties. The preliminary results of a more exhaustive study about the applicability to polymers of the most used procedure to determine elastic modulus by indentation are reported in this short communication. A departure of the experimental conditions from the theoretical assumptions and results that give rise to the Oliver and Pharr analysis is shown to occur under a wide range of experimental conditions, with applied loads and penetration depths covering several orders of magnitude and using different indenter geometries. Unloading curves with exponents significantly larger than…
Solid State Analysis of Metal-Containing Polymers Employing Mossbauer Spectroscopy, Solid State NMR and F EI TOF MALDI MS
2010
Polymers in general and metal-containing polymers in particular are often sparingly soluble or insoluble, in contrast to small molecules. Thus, special significance is attached to characterization techniques that can be applied to the materials as solids. Here, three techniques are discussed that give structural information gained from the solid material. Mossbauer spectroscopy is a powerful technique that may give information on the structure about the metal-containing moiety for about 44 different nuclei. Its use in describing the structure of the product obtained from organotin dichlorides and the unsymmetrical ciprofloxacin is presented along with the reaction implications of the result…
Pyrolysis gas chromatography-mass spectrometry in environmental analysis: Focus on organic matter and microplastic
2020
Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) has great potential within environmental analysis. This technique is mainly used for the chemical identification of macromolecules that cannot be characterized by either liquid or gas chromatography due to their big size. Through pyrolysis (controlled thermal degradation), these macromolecules are broken down into simpler molecules that can be separated by gas chromatography and detected by mass spectrometry. This technique has been traditionally used in environmental samples for the characterization of organic matter and humic substances, contaminants, lignins, etc. It attains the identification of the different types of chemical un…
Consequences of linking charged and uncharged monomers to binary copolymers studied in dilute solution. Part I: Viscometric behavior of the homopolym…
2017
Abstract Intrinsic viscosities, generalized intrinsic viscosities and viscometric interaction parameters were measured for aqueous solutions of poly(ethylene oxide) [PEO], poly(N,N-dimethyl aminoethyl methacrylate) [PR] (uncharged) and for poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} [PR+] (charged) within a wide range of molar masses. In this manner it was possible to establish the information required for the study of non-additivity effects upon the formation of binary copolymers from the monomers specified above. The following additional items were of particular interest: The effects of charging PR to PR+ and the composition dependence of the coil overlap in the case of sali…
Intrinsic Viscosities of Polymer Blends: Sensitive Probes of Specific Interactions between the Counterions of Polyelectrolytes and Uncharged Macromol…
2018
In joint dilute aqueous solutions of pullulan (PUL) and poly(sodium 4-styrenesulfonate) (PSS-Na) the Na+ ions of the polyelectrolyte interact so favorably with the monomeric units of PUL that isolated coils containing both types of macromolecules are formed upon dilution. When water is replaced against a 1 M solution of NaCl, this effect dies out because of the large surplus of Na+ ions. On the other hand, if the water contains increasing amounts of the respective counterpolymer instead of NaCl, the formation of mixed isolated coils is fostered, where a further diminution of the intrinsic viscosities is caused by the lower the solvent quality. The molar mass of PSS-Na plays an important rol…
Combined Effects of Pressure and Shear on the Phase Separation of Polymer Solutions
1998
Experimental information available in the literature on the phase separation behavior of the system trans-decalin/polystyrene as a function of pressure and shear rate for different molar masses M o...