This work examines the possibility of using POM with bimodal molecular mass distribution as the main component of the binding agent in powder injection molding (PIM technology) by studying its time-dependent properties and comparing them to monomodal POM. It is shown how the addition of short polymeric chains in bimodal POM influences its time-dependent properties in solid and molten state, which can be an important tool for the optimization of binders designed to be used in PIM technology.
COBISS.SI-ID: 12353051
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
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
This paper presents a brief overview on experimental approaches accompanied with corresponding numerical procedures for characterization of time-dependent properties of viscoelastic materials. Upgraded experimental procedure is proposed for characterization of material creep and relaxation properties from a single experiment, which are usually measured separately. In addition, newly developed numerical approaches for the construction of unique master curves, and for the analysis of time-dependent materials fatigue properties are presented. The newly developed experimental-numerical methodologies are aimed to optimize process of characterization, and give complete information on time-dependent material behaviour.
COBISS.SI-ID: 12336923
This chapter is a part of the book entitled "Some Critical Issues for Injection Molding". It gives an overview of the current state of the art of powder injection molding of metal and ceramic parts. It describes procedures of powder manufacturing, binder formulations and characteristics of the feedstock preparation, as well as the complete procedure of manufacturing parts of complex geometries by using PIM. PIM technology utilizing polyoxymethylene (POM) binder is presented as the advanced and fast procedure in PIM. However, there are some critical points pointed out in relation to this, and possibilities for the optimization of the process in different segments.
COBISS.SI-ID: 12261147