Binary and ternary blends of PC, ABS, and PMMA were studied. The blends were produced from original and recycled materials by melt mixing in a wide range of compositions. Instrumented Charpy impact testing, tensile testing, rheology investigations, and electron microscopy were carried out to determine the relationship between the deformation and fracture behavior, blend composition, morphology, and processing parameters. Resistance against unstable crack propagation was evaluated using the concepts of J-integral and crack-tipopening displacement (CTOD). The transition from ductile elastic-plastic to brittle-linear elastic fracture behavior was observed in the case of PC/ABS/PMMA blend at 10% of PMMA. Reprocessing had only a slight influence on the deformation and fracture behavior of the recycled blends. The blends produced from recycled materials proved to be competitive with the original pure materials.
The polyethylene (PE) coatings could be very promising for various branches of industry due to their chemical stability and impact resistance. Plasma modification of powder has recently attracted much interest because of new prospects to control the interfacial properties. Plasma modification also significantly enhanced the adhesion of the polymer to the substrate. Powders find wide application in various branches of industry like paintings, biotechnology, filling for composite materials etc., but the plasma modification of powder surface has not found such application as plasma modification of flat solid materials. This is due to problems connected with the three dimensional geometry, necessity of solid mixing (due to the aggregation phenomenon) and the large surface area of powders which should be treated. We investigated plasma modification of PE powder, its adhesion properties on steel surface and mechanism influencing this adhesion. PE powder was modified using various working gases and chemicals. It was found that adhesion properties were strongly influenced by concentration of oxygen containing groups and also by PE crosslinking after modification. The value of crosslinking depends on used working gas and chemicals. The ternary mixture of O2/H2O/methanol was found to be an appropriate working gas for plasma treatment of PE for adhesion purposes. The treated PE had good wettability, low crosslinking and very high adhesion to the steel substrate.
Structural changes caused by cold drawing low and high molecular weight polyethylene (M = 7 × 104 and 1.5 × 106) were investigated by using wide‐angle x‐ray diffraction, light and electron microscopy. Results obtained from drawn samples subjected to stress and samples at zero stress, revealed important differences in the behavior of these two polymers. In contrast with the low molecular weight polyethylene, the high molecular weight samples were deformed homogeneously without neck formation; the orthorhombic lattice, when subjected to stress, is transformed into a monoclinic one, not only in the initial stage, but over the whole deformation range up to breaking. The spherulitic structure in both polymers changes into the fibrillar one, while the degree of orientation attainable for the low molecular weight polyethylene is higher than that for the high molecular weight sample. During deformation of the low molecular weight polymer, cracks form between fibrils, and the fibrils become separated. Such an effect has not been observed with the high molecular weight material. After the external stress has been removed, a considerable contraction and decrease in orientation characterize the high molecular weight polyethylene. The differences in behavior of the two types of polymers are discussed in terms of different structural models.
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