The concept of materials coming from nature with environmental advantages of being biodegradable and/or biobased (often referred to as bioplastics) is very attractive to the industry and to the consumers. Bioplastics already play an important role in the fields of packaging, agriculture, gastronomy, consumer electronics and automotive, but still they have a very low share in the total production of plastics (currently about 1% of the about 300 million tonnes of plastic produced annually). Biodegradable plastics are often perceived as the possible solution for the waste problem, but biodegradability is just an additional feature of the material to be exploited at the end of its life in specific terms, in the specific disposal environment and in a specific time, which is often forgotten. They should be used as a favoured choice for the applications that demand a cheap way to dispose of the item after it has fulfilled its job (e.g. for food packaging, agriculture or medical products). The mini-review presents the opportunities and future challenges of biodegradable plastics, regarding processing, properties and waste management options.

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.

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.

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.

Modern process control is based on the use of statistical methods to improve and ensure quality, and thus reduce the process cost due to waste and rejects. The paper deals with the process capability analysis in the manufacturing of poly(ethylene-terephthalate) bottles for packaging of table oil. PET bottles are manufactured by the procedure of injection stretch blow moulding. The preforms made by injection moulding are biaxially extruded in the blow mould, with blow parameters affecting the mechanical properties, the barrier properties and the transparency of the manufactured bottle. The performance of blow moulding machine was monitored by measuring the volumes of blown bottles. Based on the collected data, the capability analysis of the blow moulding process was conducted.

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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.

The catalyst for this paper on biofuels and bioplastics was a newspaper report which appeared in January 2007. The report stated that maize prices on the Chicago Stock Exchange had hit an all-time high, while stocks were at their lowest level for ten years. The price rises and dwindling stocks were explained by the decision by President George W. Bush to cover 10% of the country's fuel consumption with ethanol. This marked the culmination of one of the most important trends in recent decades: to use agriculture products as fuel for machines-known as biofuel-rather than as food for living creatures. Food prices, for their part, rose. All of this was justifi ed by the argument that greenhouse emissions would be reduced as a consequence. Leading plastics producers, albeit to a lesser extent, are also interested in processing agriculture products in biorefi neries to obtain intermediates for plastics production. This too is symptomatic of the current drive to produce everything from natural resources, but it is based on a fallacy. Agriculture products are not natural products; they are the result of human skill and industry. Truly natural products, by contrast, are natural gas, petroleum or crude oil, natural rubber from the rainforests. Adopting a cross-scientifi c approach to take account of technical, economic and social-but not ideological-perspectives, we investigated the attempt to produce everything from renewable resources. We asked how the production of greenhouse gases, specifi cally CO 2 , can be reduced and how it can be used. Some of our answers were drawn from the writings of G. Menges. Two concepts for producing plastics from renewable raw materialsthe DuPont concept for sustainability and environmental compatibility and that developed by GE Plastics (now SABIC) for environmentally compatible polymers-are discussed in detail. The conclusion we reach is that all waste, including biomass waste, must be processed using all available methods. The idea of producing everything from renewable resources-plastics, fuels, textiles, leather, etc.-is socially absolutely unacceptable.