The main advantages of Thermoplastic Polyester Elastomers (TPE-E) are their elastomer properties as well as their ability to be processed in the same way as thermoplastic polymers (e.g., injection moulding, compression moulding and extrusion). However, TPE-Es’ properties, mainly their mechanical properties and thermal characteristics, are not as good as those of elastomers. Because of this TPE-Es are often modified with the aim of improving their properties and extending their range of application. Radiation cross-linking using accelerated electron beams is one of the most effective ways to change virgin polymers’ properties significantly. Their electrical (that is to say permittivity and resistivity measurements), mechanical (that is, tensile and impact tensile tests), as well as surface (that is, nano-indentation) properties were measured on modified/cross-linked TPE-E specimens with and/or without a cross-linking agent at irradiation doses of 0, 33, 66, 99, 132, 165 and 198 kGy. The data acquired from these procedures show significant changes in the measured properties. The results of this study allow the possibility of determining the proper processing parameters and irradiation doses for the production of TPE-E products which leads to the enlargement of their application in practice.
The goal of this research was to examine the effect of two surface modification methods, i.e., radiation cross-linking and plasma treatment, on the adhesive properties and the final quality of adhesive bonds of polypropylene (PP), which was chosen as the representative of the polyolefin group. Polymer cross-linking was induced by beta (accelerated electrons—β−) radiation in the following dosages: 33, 66, and 99 kGy. In order to determine the usability of β− radiation for these applications (improving the adhesive properties and adhesiveness of surface layers), the obtained results were compared with values measured on surfaces treated by cold atmospheric-pressure plasma with outputs 2.4, 4, and 8 W. The effects of both methods were compared by several parameters, namely wetting contact angles, free surface energy, and overall strength of adhesive bonds. Furthermore, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were conducted. According to our findings the following conclusion was reached; both tested surface modification methods significantly altered the properties of the specimen’s surface layer, which led to improved wetting, free surface energy, and bond adhesion. Following the β− radiation, the free surface energy of PP rose by 80%, while the strength of the bond grew in some cases by 290% in comparison with the non-treated surface. These results show that when compared with cold plasma treatment the beta radiation appears to be an effective tool capable of improving the adhesive properties and adhesiveness of PP surface layers.
Nowadays, it is very desirable to obtain the low cost polymeric material with the best material properties. For the best modification of the commodity and construction polymeric materials it is firstly necessary to know the basic material properties. In this study the bending and Charpy impact test specimens were fabricated via a professional FDM 3D printer Fortus 900mc, from company Stratasys, processing ABS-M30 in three build orientation XY, XZ-H and XZ-V. The 3D printed test specimens were examined to compare the effect of layer thickness and building orientation. Tensile test machine Zwick 1456 and impact pendulum Zwick HIT50P were used for bending and Charpy impact tests. Optical microscopy was utilized to perform fractography on impact test specimens to explore the effect of the layer thickness and building orientation on the fracture surface morphology of the failed specimens. This study demonstrates the need for material testing for specific processing as additive manufacturing technologies.
Grafting of poly(oxytetramethy1ene) (polytetrahydrofuran) chains containing living oxonium end groups onto polymers containing aromatic rings was investigated. The rate of grafting was found to be slow, but under favourable conditions several moles of polytetrahydrofuran can be grafted to one mole of polystyrene. Macrocations may also be grafted to the surface of insoluble polymers dispersed in a solution of grafting ions. This was proved by grafting living polytetrahydrofuran onto poly(pheny1ene oxide) or random poly(1-butene-co-styrene). Macrocations can be prepared from an anionic living polymer via transformation of the growing centers. Thus, poly(dimethylsiloxane), whose original anionic centers were transformed into cationic ones, was grafted to polystyrene. Exchange reactions were found to take place in the living system on polytetrahydrofuran or poly(dimethylsi1oxane) grafts, thus influencing their length. The graft copolymers are strong surfactants. Separation from their mixture with homopolymers by a repeated extraction of homopolymers with a solvent is difficult and sometimes impossible.
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