Search Results (18)

Analysis of the impact of aging processes induced by environmental conditions, particularly aggressive ones, on the properties of polymeric materials and products made from them has been the subject of intensive research for many years. Developing materials characterized by high resistance to the specific external factors in which these materials are used is a key issue in the context of developing a sustainable economy aimed at minimizing waste and extending the service life of polymeric components. The main objective of this research was to assess and quantify the degradation mechanisms of polymeric materials manufactured using additive Fused Deposition Modeling (FDM) technology when exposed to aggressive marine environments. To achieve this, the study analyzed the influence of seawater corrosion conditions on the changes in mechanical and rheological properties of two polymeric materials: recycled polylactide (rPLA) and a wood–polymer composite (WPC) based on PLA reinforced with wood flour (MD). The results revealed that rPLA exhibited an approximately 16% decrease in average molecular weight after 9 months of seawater exposure, accompanied by a 37% reduction in tensile strength and a 24% decrease in elastic modulus. In the case of the WPC, the molecular weight decreased by about 20%, while tensile strength and elastic modulus dropped by 30% and 51%, respectively. The findings provide quantitative evidence of the susceptibility of additively manufactured biodegradable polymers to marine-induced degradation, highlighting the necessity of further optimization for maritime and coastal applications. Full article

The new wood–plastic composites (WPC) biocomposites, a promising blend of poly(lactic acid) (PLA) and lignocellulosic fillers, are the subject of our study. We used bark and sawdust at 40, 50, and 60% as PLA fillers. The innovative use of ion implantation to modify the surface properties of the produced composites could have significant implications. Argon ions were used in three dosages (1 × 10¹⁵, 1 × 10¹⁶, and 1 × 10¹⁷ cm⁻²) at an accelerating voltage of 60 kV. The modified composites were then analyzed for changes in surface wettability, surface energy, and color. Our findings demonstrate that the dosage of argon ion implantation and the filler used have a profound impact on the properties of the modified surfaces. In general, ion implantation enhances the surface wettability of composites and pure PLA, with the recorded relationships being more pronounced in composites containing higher proportions of lignocellulosic fillers. Furthermore, the implantation of ions on the surface of composites induces changes in their color, opening up new possibilities for the field of materials science. Full article

Particle size of wood fillers used in FDM 3D printing filaments is a topic not commonly discussed in the literature. Research on traditional wood–polymer composites (WPCs) suggests that bigger particles improve the composite’s tensile properties. Is that the case at the 3D printing scale? Five variants of composites were prepared using recycled PLA and sawdust, differentiated by filler particle size (<0.2 mm, 0.2 mm–0.4 mm, 0.4 mm–0.6 mm, 0.6 mm–0.8 mm, 0.8 mm–1 mm). Current draw during extrusion, as well as tensile strength and tensile modulus, were tested. Test results of tensile strength, ranging from 9.21 MPa to 14.28 MPa, and tensile modulus, ranging from 802 MPa to 1014 MPa, have shown no clear correlation between wood particle size and tensile properties of the composites at the 3D printing scale. A clear increase in forces needed to extrude composites containing larger particles of wood was discovered, as well as the inability to extrude composites filled with the biggest tested particle size. To further explore this topic, SEM/EDS imaging of the tested composites was performed. Based on the test results, wood particle sizes ranging from one-fifth to one-half of the nozzle size are recommended for use as fillers in wood–PLA composites intended for 3D printing. Full article

Wood plastic composites (WPCs) offer a means to reduce the carbon footprint by incorporating natural fibers to enhance the mechanical properties. However, there is limited information on the mechanical properties of these materials under hostile conditions. This study evaluated composites of polypropylene (PP), polystyrene (PS), and polylactic acid (PLA) processed via extrusion and injection molding. Tests were conducted on tensile and flexural strength and modulus, heat deflection temperature (HDT), and creep analysis under varying relative humidity conditions (10% and 90%) and water immersion, followed by freeze—thaw cycles. The addition of fibers generally improved the mechanical properties but increased water absorption. HDT and creep were dependent on the crystallinity of the composites. PLA and PS demonstrated a superior overall performance, except for their impact properties, where PP was slightly better than PLA. Full article

This study investigated the closed-loop recycling of 3D-printed wood fiber (WF)-filled polylactic acid (PLA) composites via fused filament fabrication (FFF). The WF–PLA composites (WPCs) were extruded into WPC filaments (WPC_fs) to produce FFF-printed WPC parts (WPC_ps). The printed WPC_ps were reprocessed three times via extrusion and 3D-printing processes. The tensile properties and impact strengths of the WPC_fs and WPC_ps were determined. To further investigate the impact of closed-loop recycling on the surface morphology, crystallinity, and molecular weight of WPC_fs, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively, were used. After closed-loop recycling, the surface morphology of the WPC_fs became smoother, and a decrease in the pore sizes was observed; however, the tensile properties (tensile strength and elongation at break) deteriorated. With increasing numbers of recycling iterations, the molecular weight of the PLA matrix decreased, while an increase in crystallinity was observed due to the recrystallization of the low-molecular-weight PLA molecules after recycling. According to the SEM images of the recycled WPCps, their layer heights were inconsistent, and the layers were rough and discontinuous. Additionally, the color difference (ΔE*) of the recycled WPC_ps significantly increased. Compared with those of the WPC_ps after recycling them only once, the tensile strength, elongation at break, and impact strength of the WPC_ps noticeably decreased after recycling them twice. Considering the changes in various properties of the WPC_fs and WPC_ps, the FFF-printed WPC parts can be reprocessed only once through 3D printing. Full article

This study explores the possibilities of utilisation of coniferous bark as a filler in wood–polymer composites (WPCs), its impact on properties such as the modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling (TS) and water absorption (WA) after 2 h and 24 h of immersion in water and the significance of this impact compared to other factors. Six variants of bark–polylactic acid (PLA) WPCs were manufactured, differentiated by their filler content and filler particle size. As a comparison, analogous composites filled with coniferous sawdust were also manufactured. Bark-filled composites were characterised by lower TS and WA after both 2 h and 24 h of immersion, as well as lower water contact angles and surface free energy. The bark filler decreased the composites’ MORs and MOEs, while greater differences were noticed for variants filled with small particles. The type of filler was the second most important factor contributing to variance in this study, with the filler content being the most important one. Full article

The global packaging industry has been growing significantly, resulting in an increase in waste and emissions. Social responsibilities, regulations and targets are shifting companies’ priorities to various sustainable practices. This study comprised a life cycle assessment (LCA) to quantify and compare key initiatives influencing the sustainability of plastic cosmetic packaging. The life cycle environmental effects of dematerialisation, recycled content, energy-saving initiatives and renewable energy powering the manufacturing processes, and the end-of-life (EoL) recycling rates of various scenarios, were evaluated. Moreover, a variety of fossil-based and bio-based polymers, such as acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene terephthalate (PET), wood–polymer composite (WPC) and polylactic acid (PLA), were considered. The study determined that dematerialisation and recycled content had the most beneficial impacts on packaging sustainability. When 100% recycled materials were used, an overall impact reduction of 42–60% was noted for all the materials considered. Using 100% renewable energy and applying measures to reduce the energy consumption in the manufacturing stage by 50% reduced the total impact by approximately 9–17% and 7–13%, respectively. Furthermore, it was concluded that PP had the lowest environmental impacts in the majority of the case scenarios considered, by an average of 46%. Full article

Wood fibers (WFs) were treated at a fixed heat temperature (180 °C) for 2−6 h and added to a polylactic acid (PLA) matrix to produce wood−PLA composite (WPC) filaments. Additionally, the effects of the heat-treated WFs on the physicomechanical properties and impact strength of the WPC filaments and 3D-printed WPC parts using fused filament fabrication (FFF) were examined. The results revealed that heat-treated WFs caused an increase in crystallinity and a significant reduction in the number of pores on the failure cross section of the WPC filament, resulting in a higher tensile modulus and lower elongation at break. Additionally, the printed WPC parts with heat-treated WFs had higher tensile strength and lower water absorption compared to untreated WPC parts. However, most of the mechanical properties and impact strength of 3D-printed WPC parts were not significantly influenced by adding heat-treated WFs. As described above, at the fixed fiber addition amount, adding heat-treated WFs improved the dimensional stability of the WPC parts and it enabled a high retention ratio of mechanical properties and impact strength of the WPC parts. Full article

In the last two decades, there has been increased interest in research focused on developing innovative polymer composite materials for food packaging, obtained by compounding polymers with organic fillers, intended for the manufacture of food storage containers. Woodplastic composites (WPCs), due to high content of lignocellulosic filler, are consideredbiocomposites and can be used for the fabrication of such types of containers. Their formulations include, along with the matrix and the filler, functional additives. One of the most important considerations while developing a food packaging material is to choose eco-friendly additives. The suberinic acids (SAs), extracted from birch outer bark by hydrolysis in KOH water solution, were examined as lubricants in the formulation of recycled polypropylene/polylactic acid (rPP/PLA) composite filled with the alkali-treated milled birch shaving microparticles and proceeded by extrusion and injection molding. The incorporation of Sas in a birch wood-rPP/PLA composite was performed by treaing the wood microparticles with the SAs water suspension at the defined concentration. Their presence at the optimal content in the composite improved its processing by reducing the extruder rotor torque and injection pressure, which increased the mechanical properties and decreased the wettability of the composite. Full article

Wood–plastic composites (WPCs) represent composite materials that employ shredded wood combined with a thermoplastic substance, such as polylactic acid (PLA), to establish structural cohesion within the product profile. This amalgamation of materials results in a robust structure designed to fulfill specialized roles under the influence of pressure and temperature. Given the nature of the constituent materials, the resultant product can be classified as a biocomposite. The creation of such biocomposites entails a rigorous process necessitating the fine-tuning of specific parameters and suitable technologies. The foundational materials employed in this process must be both natural and biodegradable. However, it is noteworthy that natural components like fibers exhibit anisotropic behavior, wherein their mechanical attributes are contingent on the direction of the applied force. Consequently, predicting their performance during biocomposite production proves challenging. The principal objective of this study was to conduct a comparative analysis of wood-based composites incorporating PLA thermoplastic binding agents. The intention was to discern variations in density profiles arising from distinct measurement methodologies. Two measurement methods were used for the measurement: X-ray and spectrum desaturation. Additionally, the study sought to investigate the impact of introducing PLA additives at 25% and 50% concentrations on the fabrication of WPC from wood chips. The properties of these composites were assessed by considering the inherent traits of the composite materials. Full article

Wood–plastic composites (WPCs) increase the range of applications of materials by creating new material solutions. As part of this research, PLA (polylactic acid)- and HDPE (high-density polyethylene)-based composites were manufactured. Softwood sawdust or conifer bark with different sizes (large and small) were used as filler. In selected cases, the addition of 3% additives, such as calcium oxide in the case of PLA or polyethylene-graft-maleic anhydride in the case of HDPE, were tested. The manufactured composites were examined for their density profile and their susceptibility to drilling, defined by the value of the axial force occurring during drilling. The obtained results revealed that the type of matrix had the greatest influence on the axial forces during drilling. Regardless of the composite formulation, composites based on PLA had 25% to 56% higher axial forces during drilling than those based on HDPE. Furthermore, increasing the proportion of lignocellulosic fillers resulted in a decrease in the value of axial forces during drilling, with PLA composites experiencing a greater decrease than HDPE composites. The type and size of the filler had a minor impact on the axial force values during drilling. The statistical analysis indicated that the additives had a greater influence on HDPE than on PLA. Full article

In recent years, under the pressure of resource shortage and white pollution, the development and utilization of biodegradable wood-plastic composites (WPC) has become one of the hot spots for scholars’ research. Here, corn straw fiber (CSF) was chosen to reinforce a poly(lactic acid) (PLA) matrix with a mass ratio of 3:7, and the CSF/PLA composites were obtained by melt mixing. The results showed that the mechanical properties of the corn straw fiber core (CSFC) and corn straw fiber skin (CSFS) loaded PLA composites were stronger than those of the CSFS/PLA composites when the particle size of CSF was low. The tensile strength and bending strength of CSFS/CSFC/PLA are 54.08 MPa and 87.24 MPa, respectively, and the elongation at break is 4.60%. After soaking for 8 hours, the water absorption of CSF/PLA composite reached saturation. When the particle size of CSF is above 80 mesh, the saturated water absorption of the material is kept below 7%, and CSF/PLA composite has good hydrophobicity, which is mainly related to the interfacial compatibility between PLA and CSF. By observing the microstructure of the cross section of the CSF/PLA composite, the research found that the smaller the particle size of CSF, the smoother the cross section of the composite and the more unified the dispersion of CSF in PLA. Therefore, exploring the composites formed by different components of CSF and PLA can not only expand the application range of PLA, but also enhance the application value of CSF in the field of composites. Full article

Due to the content of lignocellulosic particles, wood plastic composites (WPC) composites can be attacked by both domestic and mold fungi. Household fungi reduce the mechanical properties of composites, while mold fungi reduce the aesthetics of products by changing their color and surface decomposition of the wood substance. As part of this study, the impact of lignocellulosic fillers in the form of sawdust and bark in poly (lactic acid) (PLA)-based biocomposites on their susceptibility to mold growth was determined. The evaluation of the samples fouled with mold fungi was performed by computer analysis of the image. For comparison, tests were carried out on analogous high-density polyethylene (HDPE) composites. Three levels of composites’ filling were used with two degrees of comminution of lignocellulosic fillers and the addition of bonding aids to selected variants. The composites were produced in two stages employing extrusion and flat pressing. The research revealed that PLA composites were characterized by a higher fouling rate by Aspergillus niger Tiegh fungi compared to HDPE composites. In the case of HDPE composites. The type of filler (bark, sawdust) affected this process much more in the case of HDPE composites than for PLA composites. In addition, the use of filler with smaller particles enhanced the fouling process. Full article

The use of wood particles in wood-plastic composites (WPC) is well known and similar use could occur in materials for fused deposition modeling (FDM) 3D printing. Wood particles could be one of the possible solutions in the search for natural-based materials to minimize the use of synthetic-origin materials in additive manufacturing. Wood particles for 3D printing filaments can be made from wood waste and could serve as a cheap filler or as a value-added reinforcing component, depending on their properties and incorporation. The disadvantages of wood (dimensional changes due to water adsorption and desorption) could be used as functions when dimensional change is desirable, such as in shape-changing 4D printing materials. In this research, FDM printing materials made of polylactic acid (PLA), with different amounts of wood particles, were used to design moisture-induced shape-changing bilayer actuators, which could serve as a principle for active façade or ventilation valves. The initial research shows that the wood content in the WPC causes dimensional changes and thus shape changes of the designed actuators under changing climates. The shape change depends on the ratio of the materials in the two-layered actuator and the wood content in the wood-PLA composite used, and thus on sorption. The rate of the shape change behaves in the same way: the higher the wood content, the greater the change observed. The dynamics of the hygromorphism of bimaterial composites is greater with a small amount of added hygromechanically active material. Full article

Wood-plastic composite (WPC) based on a polylactic acid (PLA) matrix is a promising material since it is biobased, degradable, sustainable, and 3D printable. However, due to its coloring, visible layers after 3D-printing, and small build volumes of these printers, a coating or gluing of parts might be required. This study investigates the influence of a dielectric barrier discharge (DBD) plasma treatment of PLA-based WPC to activate the surface and improve, e.g., coating capabilities. X-ray photoelectron spectroscopy (XPS) measurements showed the oxidation of the surface due to the formation of carbonyl and carboxyl groups. Laser scanning microscopy revealed a surface roughening after the treatment. Contact angles of water and diiodomethane decreased significantly after the plasma treatment and the consecutively calculated surface free energy increased. Finally, two practical adhesion tests revealed an improvement of the applied acrylic dispersion coating’s adhesion to the WPC surface: The assigned cross-cut class improved, and the pull-off strength increased from 1.4 to 2.3 N/mm². Full article