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Natural and wood fibre plastic composites (WPC) are among the most rapidly growing markets within the plastics industry. They are manufactured by combining either wood or other natural fibers such as flax, hemp, jute or kenaf with polymers. Thermoplastic resins, such as polypropylene, polyethylene or polystyrene, are mixed with other materials (such as wood), and form a composite product. The resulting composite can be easily processed into various shapes and can be recycled. The experiments were made to study the behaviour of the wood flour-polypropylene composite during injection moulding, and to what extent the mechanical properties deteriorate after several processing cycles, i.e. mechanical recycling. Regarding efficiency of energy recovery, the heating value of wood-thermoplastic composite with different contents of wood and thermoplastics was determined as well.

Additive manufacturing (AM) is increasingly applied in the development projects from the initial idea to the finished product. The reasons are multiple, but what should be emphasised is the possibility of relatively rapid manufacturing of the products of complicated geometry based on the computer 3D model of the product. There are numerous limitations primarily in the number of available materials and their properties, which may be quite different from the properties of the material of the finished product. Therefore, it is necessary to know the properties of the product materials. In AM procedures the mechanical properties of materials are affected by the manufacturing procedure and the production parameters. During SLS procedures it is possible to adjust various manufacturing parameters which are used to influence the improvement of various mechanical and other properties of the products. The paper sets a new mathematical model to determine the influence of individual manufacturing parameters on the polymer product made by selective laser sintering. Old mathematical model is checked by statistical method with central composite plan and it is established that old mathematical model must be expanded with new parameter beam overlay ratio. Verification of new mathematical model and optimization of the processing parameters are made on SLS machine.

If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -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.

Purpose -This paper aims to emphasize compared experimental analysis of influence of hybrid and classic moulds on the properties of moulded parts and the processing parameters. Such analysis enables optimization of processing parameters in case of the hybrid mould. Design/methodology/approach -Representative moulded part and appropriate hybrid and classic moulds have been designed and manufactured. The experimental work contains a screening design and the main central composite design for analysing the performance of both moulds and moulded parts properties. In case of hybrid mould a numerical optimization of processing parameters was used. Findings -It was found that hybrid moulds can be successfully applied for production of thin-wall moulded parts with some limitations. The compressibility of prototype mould inserts was higher compared to classic inserts. The differences in thermal properties of mould inserts materials result in different moulded part properties and mould cavity wall temperature fields. These differences can be reduced by optimizing the processing parameters. Practical implications -RT technologies can be usefully applied for fast production of moulds for injection moulding. The potential user of hybrid moulds should be aware of the influence of prototype inserts on the moulded part properties. Guidelines for optimization can be used for fast achieving of parameters from optimal processing window. Originality/value -This paper shows a detailed analysis of influence of hybrid and classic moulds on the thermoplastic moulded part properties. Some of these influences are explained in detail, which was not found in the related papers. In this paper, a further step was made by optimizing the processing parameters in case of hybrid mould.

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Abstract. In selective laser sintering (SLS) of polymer products the price of material is not the most important factor, but it does play a significant role when analysing the overall i.e. final price of the product, and therefore recycling of material is becoming an increasingly important factor, as well as the ratio of the shares in combining the original and the already used materials. In practice it is inevitable to use the products in various atmospheric conditions (UV radiation and humid environment), intentionally or unintentionally. UV light, with sun being its most common source, and average humidity in different parts of the world can be approximately from 20% to 90%, depending on time, day and geographic location. Therefore, it is necessary to determine how UV light after a longer period of time of exposure affects the product properties. The properties of the final product are also affected by the orientation in the working area of the machine. In the paper an analysis has been performed of the impact of three different types of product orientation in the machine working area and three different ratios of the used polyamide material (100% original, combined in 50:50 ratio of original and recycled and 100% recycled material after the third cycle of usage) on hardness of the polyamide product made by selective laser sintering.

This work investigates the methodology of producing a 3D-printed microreactor from the acrylic resin by PolyJet Matrix process. The PolyJet Matrix technology employs different materials or their combinations to generate 3D-printed structures, from small ones to complex geometries, with different material properties. Experimental and numerical methods served for the evaluation of the geometry and production of the microreactor and its hydrodynamic characterization. The operational limits of the single-phase flow in the microchannels, further improvements and possible applications of the microreactor were assessed based on the hydrodynamic characterization.