Search results for "Plastics"
showing 10 items of 2724 documents
A new method of nanocrystalline nickel powder formation by magnetron sputtering on the water-soluble substrates
2018
Due to the accurate and relatively easy control magnetron sputtering is an attractive technique for the synthesis of metallic particles. This work describes a new method of nickel powder production by depositing nickel on the surface of sodium chloride particles which were used as the template and are soluble in water. Ni powder with flake-like structure was obtained after washing Ni coated salt particles in ultrasonic cleaner. Salt particles and nickel powder were characterized using scanning electron microscope (SEM), energy-dispersive x-ray spectrometer, XRD and X-ray photoelectron spectroscopy (XPS) techniques. SEM images showed that thickness of the received Ni particles varied in the …
Surface reconstruction of the lamellar morphology in a symmetric poly(styrene-block-butadiene-block-methyl methacrylate) triblock copolymer: A tappin…
1996
The surface morphology of a symmetric poly(styrene-block-butadiene-block-methyl methacrylate) triblock copolymer (PS-b-PB-b-PMMA) with 6 wt % PB has been investigated by tapping mode scanning force microscopy (SFM). The results are compared to the bulk morphology as determined by transmission electron microscopy (TEM). In solvent-cast films PS/PMMA lamellae are formed, which are oriented nearly perpendicular to the free surface. Like in the bulk, also at the free film surface polybutadiene spheres are located at the lamellar PS/PMMA interface. However, contrary to the bulk, the surface morphology includes a large number of defects such as curved lamellar and disclinations, and the lamellar …
Analysis of pectin biopolymer phase states using acoustic emissions.
2019
Acoustic emissions are stress or elastic waves produced by a material under external load. Since acoustic emissions are generated from within and transmitted through the substance, the acoustic signature provides insights into the physical and mechanical properties of the material. In this report, we used a constant velocity probe with force and acoustic emission monitoring to investigate the properties of glass phase and gel phase pectin films. In the gel phase films, a constant velocity uniaxial load produced periodic premonitory acoustic emissions with coincident force variations (saw-tooth pattern). SEM images of the gel phase microarchitecture indicated the presence of slip planes. In …
An Innovative Treatment Based on Sodium Citrate for Improving the Mechanical Performances of Flax Fiber Reinforced Composites
2021
The goal of this paper is to evaluate the effectiveness of a cost-effective and eco-friendly treatment based on the use of sodium citrate (Na3C6H5O7) on the mechanical properties of flax fiber reinforced composites. To this scope, flax fibers were soaked in mildly alkaline solutions of the sodium salt at different weight concentration (i.e., 5%, 10% and 20%) for 120 h at 25 °C. The modifications on fibers surface induced by the proposed treatment were evaluated through Fourier transform infrared analysis (FTIR), whereas scanning electron microscope (SEM) and helium pycnometer were used to obtain useful information about composites morphology. The effect of the concentration of the treating …
Neutron Scattering Studies on the Crystallization of Polymers
1985
Abstract Neutron scattering on mixtures of deuterated and undeuterated molecules offer a new approach for solving long standing problems of the structure of semicrystalline polymers. The various ranges of the amount of the scattering vector q yield different informations. From small angle studies the radius of gyration Rg can be obtained, which does not change markedly by crystallization. The scattering intensity in “the intermediate angle range yields mainly the average distance of the crystalline stems. Experimental results show that not only Rg remains almost constant, but that also the pair distribution function g(r) of the monomer units for r«Rg does not change appreciably during cryst…
Chain conformation and structure in amorphous polymers as revealed by X-ray, neutron, light and electron diffraction
1976
Abstract The physical structure of the melt, the supercooled melt, and the glassy state of amorphous polymers can be characterized by the chain conformation, the local order, and the morphology. The conformation was studied by small-angle neutron scattering. The local order was characterized by pair distribution functions which were derived from electron scattering curves. In addition, model calculations were used to gain information about short-range order. The morphology was studied by means of light scattering (density and anisotropy fluctuations), small-angle X-ray scattering (density fluctuations), and magnetic birefringence measurements (orientational order). Experiments were performe…
Structure and thermodynamics in polymer blends. Neutron scattering measurements on blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitr…
1992
Abstract Neutron scattering on polymer blends of deutero-poly(methyl methacrylate) (D-PMMA) and poly(styrene-co-acrylonitrile) with 19 wt% acrylonitrile (PSAN-19) exhibits excess scattering for scattering vectors Q≲0.2 nm−1 if the volume fraction of D-PMMA is less than 0.5 and greater than 0.05. The range of occurrence and the amount of excess scattering depends to a certain degree on the procedure of sample preparation. If the excess scattering is eliminated by linear extrapolation from large to small Q in the Zimm representation, the residual scattering intensity in the small and intermediate Q-range can be interpreted by the mean field approach of de Gennes with a concentration-dependent…
Role of thermal history on quiescent cold crystallization of PET
2002
8 pags., 9 figs.
SAXS/WAXS study of the annealing process in quenched samples of isotactic poly(propylene)
1999
The structural rearrangement in samples of quenched isotactic poly(propylene) (iPP) submitted to different annealing treatments has been studied using simultaneous small- and wide-angle X-ray scattering (SAXS/WAXS) at the synchrotron radiation source of DESY, Hamburg. From a quantitative analysis of the WAXS profiles the values of the α-monoclinic, mesomorphic, and amorphous mass fractions coexisting in the material were determined. It is demonstrated that the SAXS patterns were characterized by two different long-period values that are attributed to α- and mesomorphic periodicity, respectively. The related α- and mesomorphic volume phase fractions, calculated from the analysis of the SAXS …
Synthesis and properties of model - micronetworks
1989
Microgels are small network particles with overall dimensions in the 100nm-region. Some experiments concerning the behaviour of cross-linked matter can be more easily performed using the molecular nature of μ-gels. In this publication, the synthesis and characterization by light and neutron scattering and dynamic-mechanical shear experiments of two different types of μ-gels are presented.