Maja Rujnić-Sokele

Challenges and opportunities of biodegradable plastics: A mini review:

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.

Influence of hybrid mould on moulded parts properties

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 field...

Impact of ageing, different share of recycled material and orientation on SLS polyamide product hardness

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 o...

STUDY ON THERMAL PROPERTIES OF SYNTHETIC AND BIO-BASED POLYURETHANE

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.