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Polymers that are created by the chemical polymerization of naturally occurring monomers are attracting considerable commercial interest in the last few years because of their non-toxicity, biodegradability and biocompatibility, and use of feedstock that is renewable. The development of specialized lignin compounds, such as electrically conducting polymers, engineering plastics, and polyurethane, is an area of highest interest and growth. The paper will present the comparison of the mechanical and thermal properties of conventional polyurethane and bio-based polyurethane, i. e. polyurethane based on polyols produced by liquefaction of waste wood biomass. [ABSTRACT FROM AUTHOR]

Rubber is the basis in the production of elastomeric materials which is transformed into the rubber-elastic state through the crosslinking procedure. A crosslinking agent is used for crosslinking - sulphur, as well as accelerators, activators and retarders if pre-crosslinking of rubber compound is to be prevented. Crosslinking occurs at higher temperatures. The type of used rubber determines the basic properties of the final rubber product: stability, ageing and flexibility at lower temperatures, strength and elasticity. In the work, the central composite test plan was used to study the mechanical properties of chloroprene rubber (CR) regarding different crosslinking parameters (time and temperature of crosslinking). [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is the selection of production parameters in selective laser sintering – SLS for the production of quality products (e.g. good mechanical properties). The manufacturing procedure affects the properties, which is especially significant in additive procedures, as the products are not cheap and the procedure and material need to be optimally selected.Design/methodology/approach The paper presents an analysis of the fabrication parameters in selective laser sintering (SLS) that affect the flexural properties of the finished product. Findings The influence of a new parameter has been found, the overlay ratio, and using the mathematical and scheme method, the selection of parameters for obtaining the optimal flexural properties has been proposed.Originality/value The paper presents a new mathematical model for the calculation of the processing parameters in SLS of polymer products and gives a diagram for the determination of which parameters are the best to use for practical purposes. [ABSTRACT FROM AUTHOR]

Injection moulding is one of the most important processes of plastics and rubber compounds processing. It enables the production of very complex plastics and rubber parts, even parts made of different plastics and rubber compounds, in one cycle. The system for injection moulding of polymers consists of different elements such as the mould, injection moulding machine and device for mould temperature regulation (tempering), and additional elements: dryers, robots, etc. For successful injection moulding, optimisation of moulded part material selection as well as elements of the injection moulding system is necessary. All of the mentioned factors consume signifi cant amounts of energy. The paper presents the analysis of energy consumption in injection moulding systems, as well as the possibilities of energy savings in injection moulding process, starting with material selection, in order to obtain a more energy effi cient process. [ABSTRACT FROM AUTHOR]

Injection moulding is one of the most important processes of cyclic polymer and other materials processing. It enables the production of very complex parts, in one cycle. For successful injection moulding, injection moulding system is necessary. It consists of main elements: the mould, injection moulding machine and device for mould temperature regulation (tempering), and additional elements: dryers, robots etc. All of the mentioned elements consume significant amounts of energy. The paper presents the analysis of the possibilities of energy savings in injection moulding process, starting with moulded part geometry, in order to obtain more energy efficient process. [ABSTRACT FROM AUTHOR]

The paper presents phases of the development from the idea to the final product using the case of a letter opener which contains the visual identity (logotype) of the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, which has been adapted for the ninetieth anniversary of the Faculty. [ABSTRACT FROM AUTHOR]

Rapid prototyping (RP) can substantially shorten the time and reduce the cost of developing a new product from the initial idea to production. Rapid prototyping can help in recognizing the basic defects whose subsequent correction may prove very expensive, especially if they have already been made when the product is ready for production. There are also many restrictions of RP procedures, primarily in the number of available materials and their properties, which may differ significantly from the properties of end product materials. In this work, based on the stipulated standards of the 3D printing machines ( ZPrinter 310 Plus) and the hybrid Polyjet technique ( Objet Eden 330), adequate test specimens were made. Furthermore, with adequate equipment, we carried out the analysis of the dimensions, roughness of surfaces, and mechanical properties of prototype test specimens. Then, based on the data obtained by testing of properties, we provided a critical commentary regarding the data stipulated by their producers. [ABSTRACT FROM AUTHOR]

In today's world environmental protection plays an important role. This also includes the rivers, lakes, seas and oceans. The general problem in the seas and oceans, among other things, are the discarded plastic products. Such fl oating plastic products act as absorbers of heavy metals, pesticides, polychlorinated biphenyls (PCBs) and other toxins that then get accumulated in sea animals, and consequently in humans as well. The most common sources of pollution are the ships (35 to 85%), i.e. people who throw various products into the sea, lost fi shermen's nets and waste from rivers or brought by the wind. The need to reduce the quantities of discarded non-degradable plastics in sea, has led to the development of marine degradable materials that after having been discarded into water (sea, lake and river) degrade completely after a certain time. The paper analyzes the possibility of processing the marine degradable material using the injection moulding process, and also the testing of mechanical properties has been performed. Its degradability in the sea has been tested as well as the applicability of the material for manufacturing of products that come into close contact with food. [ABSTRACT FROM AUTHOR]