Low density polyethylene (LDPE) was exposed to multiple consecutive extrusion cycles to simulate the process of mechanical recycling. W characterized thermal, rheological, mechanical and morphological properties. The results show that simulated recycling did not significantly change thermal properties of LDPE. However, results from rheological measurement, crystallinity, creep measurement and GPC suggest that thermal degradation and gelation of LDPE occur after extensive extrusion which leads to crosslinking of the polymer chains.
COBISS.SI-ID: 12490267
The chapter reviews the experimental techniques and the mathematical formalism needed for the characterization and modeling of the time-dependent mechanical material functions, discusses limitations of the existing theories (models), and presents some latest developments in the mathematical modeling of viscoelastic material functions.
COBISS.SI-ID: 11881243
Characterization of time- and/or frequency-dependent material properties usually requires shifting of the measured segments according to the Time-Temperature Superposition principle. This paper presents a closed form mathematical methodology (CFS) which completely removes ambiguity related to the manual shifting procedures. The derivation of the shifting algorithm is presented, and its validation using several simulated- and real- experimental data. It has been shown that error caused by shifting performed with CFS is at least 10–50 times smaller then the underlying experimental error.
COBISS.SI-ID: 11702043
The work discusses new possibilities of modifying the functionality of polymer products by changing their material structure during processing and consequently the time-dependent properties which define the durability of the final product. By analysing the low density polyethylene extrudates produced with a laboratory extruder, we observed that changing the processing conditions improves the durability of extrudates by several orders of magnitude. This opens new possibilities in the field of modifying the functionality of polymer products, and hence, better competitiveness on the world market.
COBISS.SI-ID: 11292955
Elastomeric materials (tire-rubber) are time dependent (viscoelastic) materials, which characteristics strongly depend on time, temperature and rate of mechanical loading. Almost inexhaustible source of elastomeric component is represented by discarded tires, which are also major ecological problem. Solving this ecological problem is possible with recycling of tire-rubber, for example, for producing elastomeric-thermoplastic and elastomeric-concrete composites. From the review of world scientific literature in the field of physical properties of the concrete with added granular rubber from discarded tires it is evident that they have number of advantages compared to the conventional concrete, such as: better deformability, better ability of damping mechanical vibrations, lower thermal conductivity and better resistance to freezing and thawing. Thus, it would be possible to use concrete with added granular rubber in construction applications, where damping of mechanical vibration is needed (eg, buildings and machinery foundations).
COBISS.SI-ID: 12607259