The Influence of the Direction of Wood Cutting on the Vibration and Noise of Chainsaws

Chainsaws generate high levels of vibrations and noise during work. Regardless of the type of their drive (electric, combustion) chainsaws excel TLVs (Threshold Limited Values) of vibration accelerations and the A-weighted sound level specified for eight-hour working day. The intensity of a vibro-acoustic impact of chainsaws on their operators depends on many factors. One of them is the type of the drive. This is due to significant differences in chainsaw design (inter alia characteristics of the drive, rotational speed, quasi-constant for an electric drive and variable for a combustion one). For chainsaws of the same or alike power and different type of the drive levels of vibrations and noise may vary. In this article noise levels and frequency weighted vibration accelerations for different direction of cutting kerf have been compared. Tests were performed with the same interchangeable cutting set (guide bar, cutting chain). The repeatability of conditions of the cutting process was ensured

Compatibility of Sustainable Mater-Bi/poly(ε-caprolactone)/cellulose Biocomposites as a Function of Filler Modification

Despite their popularity and multiplicity of applications, wood–polymer composites (WPCs) still have to overcome particular issues related to their processing and properties. The main aspect is the compatibility with plant-based materials which affects the overall performance of the material. It can be enhanced by strengthening the interfacial adhesion resulting from physical and/or chemical interactions between the matrix and filler, which requires introducing a compatibilizer or a proper modification of one or both phases. Herein, the impact of cellulose filler modifications with varying contents (1–10 wt%) of hexamethylene diisocyanate (HDI) on the compatibility of Mater-Bi/poly(ε-caprolactone) (PCL)-based biocomposites was evaluated. An analysis of surface wettability revealed that the filler modification reduced the hydrophilicity gap between phases, suggesting compatibility enhancement. It was later confirmed via microscopic observation (scanning electron microscopy (SEM) and atomic force microscopy (AFM)), which pointed to the finer dispersion of modified particles and enhanced quality of the interface. The rheological analysis confirmed increased system homogeneity by the reduction in complex viscosity. In contrast, thermogravimetric analysis (TGA) indicated the efficient modification of filler and the presence of the chemical interactions at the interface by the shift of thermal decomposition onset and the changes in the degradation course.This work was supported by the National Science Centre (NCN, Poland) in the frame of SONATINA 2 project 2018/28/C/ST8/00187—Structure and properties of lignocellulosic fillers modified in situ during reactive extrusion. The study was partially co-funded under project with grants for education allocated by the Ministry of Science and Higher Education in Poland executed under the subject of No 0613/SBAD/4820

Morphology, Thermo-Mechanical Properties and Biodegradibility of PCL/PLA Blends Reactively Compatibilized by Different Organic Peroxides

Reactive blending is a promising approach for the sustainable development of bio-based polymer blends and composites, which currently is gaining more and more attention. In this paper, biodegradable blends based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were prepared via reactive blending performed in an internal mixer. The PCL and PLA content varied in a ratio of 70/30 and 55/45. Reactive modification of PCL/PLA via liquid organic peroxides (OP) including 0.5 wt.% of tert-butyl cumyl peroxide (BU), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (HX), and tert-butyl peroxybenzoate (PB) is reported. The materials were characterized by rotational rheometer, atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile tests and biodegradability tests. It was found that the application of peroxides improves the miscibility between PCL and PLA resulted in enhanced mechanical properties and more uniform morphology. Moreover, it was observed that the biodegradation rate of PCL/PLA blends reactively compatibilized was lower comparing to unmodified samples and strongly dependent on the blend ratio and peroxide structure. The presented results confirmed that reactive blending supported by organic peroxide is a promising approach for tailoring novel biodegradable polymeric systems with controllable biodegradation rates.This research work was funded by the National Science Centre (NCN Poland) grant number PRELUDIUM 15 project 2018/29/N/ST8/02042

The effect of glycerin content in sodium alginate/poly(vinyl alcohol)- based hydrogels for wound dressing application

The impact of different amounts of glycerin, which was used in the system of sodium alginate/poly(vinyl alcohol) (SA/PVA) hydrogel materials on the properties, such as gel fraction, swelling ability, degradation in simulated body fluids, morphological analysis, and elongation tests were presented. The study shows a significant decrease in the gel fraction from 80.5 2.1% to 45.0 1.2% with the increase of glycerin content. The T5 values of the tested hydrogels were varied and range from 88.7 C to 161.5 C. The presence of glycerin in the matrices significantly decreased the thermal resistance, which was especially visible by T10 changes (273.9 to 163.5 C). The degradation tests indicate that most of the tested materials do not degrade throughout the incubation period and maintain a constant ion level after 7-day incubation. The swelling abilities in distilled water and phosphate buffer solution are approximately 200–300%. However, we noticed that these values decrease with the increase in glycerin content. All tested matrices are characterized by the maximum elongation rate at break in a range of 37.6–69.5%. The FT-IR analysis exhibits glycerin changes in hydrogel structures, which is associated with the cross-linking reaction. Additionally, cytotoxicity results indicate good adhesion properties and no toxicity towards normal human dermal fibroblasts

Porównanie technik pomiarowych typu off-line, on-line i in-line stosowanych w ocenie właściwości reologicznych kompozytów polietylenowych z węglanem wapnia

The article has presented comparative tests of the rheological characteristics of lowdensity polyethylene (LDPE) with an addition of calcium carbonate (CaCO3), containing 7, 14, 21 and 28 wt % of filler, respectively. The measurements were carried out by an off -line measuring technique (using a modified dead-weight plastometer), an on-line measuring technique (with a gear pump capillary rheometer) and an in-line measuring technique (with an extruder rheometer). The rheological parameters of the polymeric materials were determined based on the Ostwald de Waele powerlaw model at a temperature of 170 °C. The effect of calcium carbonate addition on the characteristic of operation of each of the employed instruments, the flow curves, the viscosity curves, and the values of power-law index (n) and consistency factor (K) have been determined.Przedstawiono badania porównawcze charakterystyk reologicznych kompozytów polietylenu małej gęstości (LDPE) z dodatkiem 7, 14, 21 i 28 % mas. węglanu wapnia (CaCO3). Zastosowano techniki pomiarowe typu off-line (zmodyfikowany plastometr obciążnikowy), on-line (reometr kapilarny z pompą zębatą) oraz in-line (reometr wytłaczarkowy). Parametry reologiczne materiałów polimerowych wyznaczano w temperaturze170 °C na podstawie modelu potęgowego Ostwalda-de-Waele. Określano wpływ dodatku węglanu wapnia na charakterystykę pracy każdego z zastosowanych urządzeń, przebieg krzywych płynięcia, przebieg krzywych lepkości oraz wartości wykładnika płynięcia (n) i współczynnika konsystencji (K)

Polylactide: from Synthesis and Modification to Final Properties

The article reports ways and trends in polylactide (PLA) modification methods concerning literature data. The paper consists of two parts and presents the process of polylactide production, and the connection of changes in its properties with the polymer structure obtained thanks to appropriate process conditions and methods of its final polymer properties improvement. Discussing both the most advantageous properties and disadvantages, the possibilities of increasing the scope of its applicability in reference to selected modification methods were presented and discussed. The presented research results related to various modification methods arrange the knowledge from the discussed scope, indicating the best possible effects and limitations. The most considerable emphasis is on the methods and results obtained from heterogeneous nucleation and incorporating various fillers in the PLA matrix. The other methods, like applying chemical interaction methods (crosslinking, using chain extenders), development of polymer blends, copolymerization, and plasticization, are presented synthetically. In summary, the review present and organizes the achievements in the possibility of modifying the most prospective biodegradable polymer, which is PLA

Effect of Quinacridone Pigments on Properties and Morphology of Injection Molded Isotactic Polypropylene

Two quinacridone pigments were added (0.01; 0.05; 0.1; 0.5; 1; 2 wt%) to isotactic polypropylene (iPP), and their influence on mechanical and thermomechanical properties were investigated. Complex mechanical and thermomechanical iPP properties analyses, including static tensile test, Dynstat impact resistance measurement, and hardness test, as well as dynamic mechanic thermal analysis (DMTA), were realized in reference to morphological changes of polymeric materials. In order to understand the differences in modification efficiency and changes in polymorphism of polypropylene matrix caused by incorporation of pigments, differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) experiments were done. Both pigments acted as highly effective nucleating agents that influence morphology and mechanical properties of isotactic polypropylene injection molded samples. Differences between polypropylene samples nucleated by two pigments may be attributed to different heterogeneous nucleation behavior dependent on pigment type. As it was proved by WAXS investigations, the addition of γ-quinacridone (E5B) led to crystallization of polypropylene in hexagonal phase (β-iPP), while for β-quinacridone (ER 02) modified polypropylene no evidence of iPP β-phase was observed

The Influence of Sub-Zero Conditions on the Mechanical Properties of Polylactide-Based Composites

Polylactide-based composites filled with waste fillers due to their sustainability are a subject of many current papers, in which their structural, mechanical, and thermal properties are evaluated. However, few studies focus on their behavior in low temperatures. In this paper, dynamic and quasi-static mechanical properties of polylactide-based composites filled with 10 wt% of linseed cake (a by-product of mechanical oil extraction from linseed) were evaluated at room temperature and at −40 °C by means of dynamic mechanical analysis (DMA), Charpy’s impact strength test and uniaxial tensile test. It was found that the effect of plasticization provided by the oil contained in the filler at room temperature is significantly reduced in sub-zero conditions due to solidification of the oil around −18 °C, as it was shown by differential scanning calorimetry (DSC) and DMA, but the overall mechanical performance of the polylactide-based composites was sufficient to enable their use in low-temperature applications

Limitations of Short Basalt Fibers Use as an Effective Reinforcement of Polyethylene Composites in Rotational Molding Technology

The rotational molding technology is becoming more popular and even outstanding some of the conventional polymer processing technologies. The production of polymer composites via this technology is still not described thoroughly. This work discusses the possibilities of obtaining polyethylene composites reinforced with short basalt fibers. Two methods of incorporating the fibrous fillers, dry-blending and through preliminary extrusion, are concerned. The application of the extrusion step to mixed polymer matrix with basalt fiber results in better distribution of basalt fibers than the direct dry blending polymer powder with fiber in the mold. The basalt fibers from rotomolded samples prepared from melt mixed plastic powder significantly reduced their length, leading to a substantial limitation in their reinforcing effect on the polymer matrix. The possible reinforcing effect was evaluated in a mechanical test such as a tensile test, impact test, and hardness. Optical microscopy helped in the investigation of the distribution of basalt fibers. Not only the physical structure of composites was examined, but also the chemical composition using the Fourier transform infrared spectroscopy. The spectroscopic analysis confirms a properly realized technological process without degradation caused by rotational molding or additional melt blending. The production of good-quality rotomolded composites reinforced with basalt fibers depends on the method of incorporating the fibrous filler

Recent Advances in Development of Waste-Based Polymer Materials: A Review

Limited petroleum sources, suitable law regulations, and higher awareness within society has caused sustainable development of manufacturing and recycling of polymer blends and composites to be gaining increasing attention. This work aims to report recent advances in the manufacturing of environmentally friendly and low-cost polymer materials based on post-production and post-consumer wastes. Sustainable development of three groups of materials: wood polymer composites, polyurethane foams, and rubber recycling products were comprehensively described. Special attention was focused on examples of industrially applicable technologies developed in Poland over the last five years. Moreover, current trends and limitations in the future “green” development of waste-based polymer materials were also discussed