The growth of poultry meat production is increasing industrial waste quantities every year. Feathers represent a huge part of the waste, and international directives and restrictions prevent landfilling of such biodegradable materials with high burning values. Furthermore, with their unique properties, poultry waste feathers are already a reliable resource for many byproducts, such as keratin extraction, fibres, hydrogel production, etc., all trying to achieve a high-added value. However, mass reduction of waste feathers into useful applications, such as development of alternative building materials, is also an important aspect. To take advantage of feathers’ thermal insulation capabilities, sound damping, and biodegradability, we worked towards mixing waste feathers with wood residues (wood shavings, dust, and mixed residues) for production of composite fibreboards, comparable to the market’s medium density fibreboards. The emphasis was to evaluate waste poultry feathers as the component of natural insulation composites, along with mixed waste wood residues, to improve their mechanical properties. Various composite fibreboards with different shares of wood and feathers were produced and tested for mechanical, thermal, and acoustic properties, and biodegradability, with comparison to typical particle boards on the market. The addition of waste feather fibres into the fibreboards` structure improved thermal insulation properties, and the biodegradability of fibreboards, but decreased their bending strength. The sound transition acoustic loss results of the presented combination fibreboards with added feathers improved at mid and high frequencies. Finally, production costs are estimated based on small scale laboratory experiments of feather processing (cleaning and drying), with the assumption of cost reduction in cases of large industrial application.
Wear resistance is one of the most important physical properties of the artificial teeth used in acrylic dentures. The goal of this research was to synthesize a new composite material made of matrix Poly-(methyl methacrylate)-PMMA with different percentages (2 % and 3 % of volume fractions) of zinc-oxide nanoparticles (ZnO NPs) as reinforcing elements, to improve its mechanical properties. The dynamic mechanical behaviour of this composite was studied through the DMA method in comparison to the pure PMMA supported by the characterization of their microstructures. Then the wear resistance was analysed on the samples, which were prepared in the form of teeth. In this context their vertical height loss was measured after 100,000 chewing cycles on a chewing simulator, before and after the artificial thermal ageing. Investigations showed that the PMMA/ZnO NP composites dampened the vibrations better than the pure PMMA, which could be assigned to the homogenous distribution of ZnO NPs in the PMMA matrix. It was found that the mean vertical height loss for the pure PMMA teeth was significantly higher (more than 4 times) compared to composite teeth made with ZnO NPs. Introducing the thermal artificial ageing led to the finding that there was no effect on the height loss by the composite material with 3 % of volume fractions of ZnO NPs. Based on this it was concluded that PMMA/ZnO NPs composites showed improved in-vitro wear resistance compared to acrylic-resin denture teeth, so this new composite material should be preferred when occlusal stability is considered to be of high priority. Keywords: poly-(methyl methacrylate)-PMMA, zinc-oxide nanoparticles, composite, resin teeth Odpornost proti obrabi je ena izmed najbolj pomembnih fizikalnih lastnosti umetnih zob pri akrilnih protezah. Cilj te raziskave je bil sintetiziranje novega kompozitnega materiala, izdelanega iz matrice poli-(metil meta akrilata)-PMMA z razli~nimi volumskimi odstotki (2 % in 3 %) nanodelcev cinkovega oksida (ZnO NPs), uporabljenimi kot oja~itveni element za izbolj{anje mehanskih lastnosti materiala. Dinami~no mehansko obna{anje teh kompozitov smo raziskali z metodo DMA v primerjavi s istim PMMA, ter s karakterizacijo njihovih mikrostruktur. Nato je bila analizirana odpornost proti obrabi na vzorcih, ki so bili pripravljeni v obliki zob. Izmerjena je bila njihova navpi~na izguba vi{ine po 100.000`ve~ilnih ciklih na`ve~ilnem simulatorju, pred in po umetnem toplotnem staranju. Preiskave so pokazale, da so PMMA/ZnO NPs kompoziti bolje bla`ili vibracije kot~isti PMMA, kar lahko pripi{emo homogeni porazdelitvi ZnO NPs v PMMA matrici. Ugotovili smo, da je bila povpre~na navpi~na izguba vi{ina za~isti PMMA zob znatno vi{ja (ve~kot 4×) v primerjavi s kompozitnimi zobmi z ZnO NPs. Umetno toplotno staranje ni imelo u~inka na izgubo navpi~ne vi{ine zoba iz kompozitnega materiala s 3 volumskimi % ZnO NPs. Na podlagi tega smo sklenili, da imajo kompoziti PMMA/ZnO NPs izbolj{ano in vitro odpornost proti obrabi, v primerjavi z zobno protezo iz akrilne smole, zato n...
We investigated the effects of two different types of impact modifiers, i.e. core-shell rubber and aliphatic polyester, on the mechanical and thermal properties of polylactide (PLA) filaments for 3D printing. First, PLA/impact modifier blends with various concentrations of impact modifiers were prepared by melt blending in a co-rotating twin screw extruder and test specimens by injection molding. The mechanical and thermal properties of blends were investigated by tensile and bending tests, dynamic mechanical analysis (DMA) and Charpy impact test. It was found that core-shell rubber remarkably improved Charpy impact strength at loadings above 5 wt % (up to 746 %). As shown by DMA, the PLA/10 wt % core-shell rubber blend exhibited better damping performance as compared to neat PLA over the whole examined frequency range, especially at high frequencies, which explained the increase in impact strength. The filament for a fused deposition modeling (FDM), 3D printer was prepared from blend with the highest impact strength (PLA/10 wt % core-shell rubber), whereas PLA and acrylonitrile-butadiene-styrene copolymer (ABS) filaments were used for reference. Test specimens were prepared by using a consumer FDM 3D printer. The mechanical and thermal properties were investigated by tensile and bending tests, DMA, Charpy impact test, and ultra-fast differential scanning calorimetry (Flash DSC). Specimens from PLA blend exhibited 109 % increase in Charpy impact strength as compared to neat PLA. In contrast to injection molded specimens, 3D printed PLA blend exhibited higher tensile E modulus than neat PLA, which was ascribed to improved interlayer adhesion. Moreover, DMA and Flash DSC analysis of 3D printed specimens showed an increase in the glass transition temperature as compared to injection molded specimens. This phenomenon was ascribed to reduction of free volume because of slow cooling in 3D printing process, which is also the reason for increased tensile E modulus of the PLA blend. All tested PLA, PLA blend and ABS filaments were in amorphous state as shown by Flash DSC analysis. Bending test showed an increased toughness of PLA blend in comparison to neat PLA and also higher toughness as compared to ABS. The modified polylactide (PLA/10 wt % core-shell rubber) filament thus combines easy processability of PLA filament and impact toughness of ABS filament.
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