The influence of the processing temperature of polylactide (PLA) on the structure geometry changing (SGC) and its functional properties were analyzed. The PLA samples subjected to testing were manufactured using incremental fused deposition modeling technology (FDM) with processing temperatures ranging from 180°C to 230°C. The topography of the PLA surfaces formed during heat dissipation and generated by the work table was analyzed. The roughness measurements were carried out using the profile method in accordance with PN ISO 3274: 2011. Registered profiles of the surfaces were analyzed numerically in fractal terms using the method of the S(Δx) structure function. The functional properties of the PLA surface were evaluated on the basis of Abbott-Firestone curves, according to PN EN ISO 13565–2: 1999.

Studies on packaging made of polylactide (PLA) subjected to long-term influence of soil environment conditions have been presented in this paper. The scientific objective of this study was to determine changes in selected properties of the PLA packaging after long-term incubation in soil. These changes were investigated by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography. The structure, thermal properties, and disintegration degree of the packaging after their three-year incubation in soil have been discussed. It was found that the PLA packaging did not disintegrate significantly in the soil environment, and slight changes in their structure and lack of significant changes in thermal properties indicate that the efficiency of their degradation in soil conditions after three years is very low. This was mainly due to inadequate temperatures in the soil. It was also found (based on the results of scanning electron microscopy and gel permeation chromatography) that initiation of the biodegradation process took place and that this process is much faster than in the case of conventional non-biodegradable polymers. The results are confirmation that materials obtained of various biodegradable polymers (not only PLA) should be biodegradable only under strictly defined conditions, allocated to a specific type of polymer, i.e. those in which they are easily and quickly biodegradable

In the paper presented are results of a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened sodium silicate base sands (SSBS) prepared of high-silica base sand and a PLA (Polylactide) 3D-prited (3DP) mould walls. Measurements of power loss of microwave radiation (P _in) expressed by a total of absorbed power (P _abs), output power (P _out) and reflected power (P _ref) were carried-out on a stand of semiautomatic microwave slot line for determining balance of microwave power emitted into selected multimaterial systems. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands and prepared by fused deposition modelling (FDM) 5 mm polylactide (PLA) walls with grid infill density from 25% to c.a. 100% served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological importance for microwave manufacture of high-quality casting sand moulds and cores in possibility of use 3D-printed mould tools and core boxes. It was found that apparent density of SSBS placed in a waveguide with PLA walls influences parameters of power output (P _out) and power reflected (P _ref). The PLA wall position and grid infill density were identified to have a limited effect on effectiveness of absorbing microwaves (P _abs).

In sand casting, Fused Deposition Modeling (FDM) printing by using Poly Lactic Acid (PLA) filament is one of the innovative foundry technologies being adopted to substitute traditional pattern making. Several literatures have reported the influence of process parameters such as raster angle and print speed on some mechanical properties of FDM-printed, PLA-prototypes used in other applications. This study investigated the effects of interior fill, top solid layer, and layer height on the compressive strength of rapid patterns for sand casting application. Different values of the process parameters were used to print the pre-defined samples of the PLA-specimens and a compression test was performed on them. The coupled effects of the process parameters on compressive strength were investigated and the optimum values were determined. Interior fill of 36%, layer height of 0.21 mm and top solid layer of 4 were found to produce a FDM-printed, PLApattern that sustained a compaction pressure of 0.61 MPa. A simulation analysis with ANSYS® to compare failure modes of both experiment and model shows a similarity of buckling failure that occurred close to the base of each specimen.

The article presents the results of the research related to the decomposition of polylactic acid (PLA)/halloysite nanotube (HNTs) biocomposites into a simple organic form. After manufacturing the nanocomposites, the evaluation of the composting process simulation was conducted using the biodegradation method. First, the selected properties of PLA/HNTs biocomposites, such as density, water absorption, and impact strength were tested. Next, the impact of the composting process on the behavior of PLA/HNTs composites was investigated from 30 to 90 days. Finally, the loss of mass of the composites, hardness, and the structural changes of biocomposites under the composting conditions before and after the composting were evaluated using SEM microscopy. The results showed that the PLA modified by HNT particles has biodegradation-friendly properties and therein is fully suitable for organic recycling. Due to this, in the coming years, it may contribute to the replacement of non-biodegradability polymers, i.e. polyolefins and polyesters, and reduction of plastic packaging wastes.

The transition to circular economy requires diversifying material sources, improving secondary raw materials management, including recycling, and finally finding sustainable alternative materials. Both recycled and bio-based plastics are often regarded as promising

alternatives to conventional fossil-based plastics. Their broad application instead of fossilbased plastics is, however, frequently the subject of criticism because of offering limited

environmental benefits. The study presents a comparative life cycle assessment (LCA) of

fossil-based polyethylene terephthalate (PET) versus its recycled and bio-based counterparts. The system boundary covers the plastics manufacturing and end-of-life plastic management stages (cradle-to-cradle/grave variant). Based on the data and assumptions set

out in the research, recycled PET (rPET) demonstrates the best environmental profile out

of the evaluated plastics in all impact categories. The study contributes to circular economy in plastics by providing transparent and consistent knowledge on their environmental

portfolio.