In this paper, four varieties of wood flour (WF)/poly (lactic acid) (PLA) composites by organo‐montmorillonite (OMMT) modification were fabricated via different modification process. The distribution ...of OMMT was characterized and the mechanical capacities of these composites were tested. After different OMMT‐modified process, the mechanical capacities of composites were distinctly different. However, except for the impact strength, almost the whole mechanical capacities showed improvements after modifying by OMMT; composite made of pure PLA and OMMT‐modified WF behaved the best mechanical properties, while composite made of pure WF and OMMT‐modified PLA behaved the worst; either for PLA modified by OMMT or WF/PLA composites modified by OMMT, the existence of the OMMT aggregates could cause damage to the mechanical properties. However, intercalated OMMT into WF or WF/PLA composite was beneficial to the mechanical properties.
In recent years, additive manufacturing has become a regular process in various industries, and consequently there is an increasing need to evaluate the environmental aspects of this technology and ...its associated materials. In this paper, comparative cradle-to-grave life cycle assessments between a conventional product and a 3D-printed alternative made of polylactic acid (PLA) and PLA-wood material were investigated based on the standard ISO 14044:2006. The environmental impact of each product was quantified for 18 categories. The goal of life cycle assessment (LCA) was to determine whether the use of 3D printed PLA/PLA-wood products can be a sustainable alternative to traditional metal products. The paper presents a case study in which a comparative LCA was conducted. The results show that a metal part manufactured using conventional subtractive processes (milling, drilling, welding, etc.) has a higher environmental impact compared to 3D-printed alternatives made from renewable materials. However, there are many sub-issues that need to be adequately addressed.
Posljednjih je godina aditivna proizvodnja postala redoviti proces u raznim industrijama, a posljedično se pojavila sve veća potreba za procjenom ekoloških aspekata te tehnologije i s njom povezanih materijala. U ovom su radu ispitane i uspoređene procjene životnog vijeka konvencionalnog proizvoda „od kolijevke do groba” te 3D isprintane alternative izrađene od polilaktične kiseline (PLA) i PLA-drvnog materijala na temelju standarda ISO 14044:2006. Utjecaj svakog proizvoda na okoliš kvantificiran je unutar 18 kategorija. Cilj procjene životnog vijeka takvih proizvoda (LCA) bio je utvrditi može li uporaba 3D printanih PLA/PLA-drvnih proizvoda biti održiva alternativa tradicionalnim metalnim proizvodima. U radu je prikazana studija slučaja u kojoj je provedena komparativna procjena životnog vijeka – LCA. Rezultati pokazuju da metalni dio proizveden primjenom konvencionalnih subtraktivnih procesa (glodanja, bušenja, zavarivanja itd.) ima veći utjecaj na okoliš nego 3D isprintane alternative izrađene od obnovljivih materijala. Međutim, u vezi s tim postoje i mnoga potpitanja koja se moraju adekvatno riješiti.
Conductive and degradable nanofibrous scaffolds have great potential in promoting cell growth, proliferation, and differentiation under an external electric field. Although the issue of inferior ...electrical conductivity in body fluids still exists, polyaniline (PANI)-based degradable nanofibers can promote cell adhesion, growth, and proliferation. To investigate whether the effect is caused by the PANI morphology, we selected three inorganic acids as dopants in the process of PANI in situ oxidative polymerization: hydrochloric acid, sulfuric acid, and perchloric acid. The obtained polyaniline/polylactic acid (PANI/PLA) composite nanofibers were characterized via SEM, FTIR, and XPS analysis, and we confirmed that the PLA nanofibers were successfully coated by PANI without any change to the porous structure of the PLA nanofibers. The in vitro mechanical properties and degradability indicated that the oxidation of acid dopants should be considered and that it was likely to have a higher oxidation degradation effect on PLA nanofibers. The contact angle test demonstrated that PANI/PLA composite nanofibers with different surface morphologies have good wettability, implying that they meet the requirements of bone tissue engineering scaffolds. The surface roughness and cell viability demonstrated that different PANI morphologies on the surface can promote cell proliferation. The higher the surface roughness of the PANI, the better the biocompatibility. Consequently, the regulated surface morphology of PANI/PLA composite nanofibers via different acids doping has positive effect on biocompatibility in tissue engineering.
Off-the-shelf hip joints are considered essential parts in rehabilitation medicine that can help the disabled. However, the failure of the materials used in such joints can cause individual ...discomfort. In support of the various motor conditions of the influenced individuals, the aim of the current research is to develop a new composite that can be used as an acetabular liner inside the hip joint. Polylactic acid (PLA) can provide the advantage of design flexibility owing to its well-known applicability as a 3D printed material. However, using PLA as an acetabular liner is subject to limitations concerning mechanical properties. We developed a complete production process of a natural filler, i.e., date pits. Then, the PLA and date pit particles were extruded for homogenous mixing, producing a composite filament that can be used in 3D printing. Date pit particles with loading fractions of 0, 2, 4, 6, 8, and 10 wt.% are dispersed in the PLA. The thermal, physical, and mechanical properties of the PLA–date pit composites were estimated experimentally. The incorporation of date pit particles into PLA enhanced the compressive strength and stiffness but resulted in a reduction in the elongation and toughness. A finite element model (FEM) for hip joints was constructed, and the contact stresses on the surface of the acetabular liner were evaluated. The FEM results showed an enhancement in the composite load carrying capacity, in agreement with the experimental results.
This article reports joining feasibility of polylactic acid-polyether ketone ketone-hydroxyapatite-chitosan composite scaffold with consumable tool in friction stir spot welding (FSSW) as a novel ...process. Also, investigations have been made for mechanical, thermal, and morphological characteristics of the joints prepared. The results for joint strength are supported with axial/transverse force and interface temperature measurement for bone scaffolds. The FSSW process parameters, namely rotational speed, pin depth, and stirred time, have been varied to correlate the changes in force and temperature with mechanical and morphological properties. The results of the study highlighted that ultimate tensile strength (6.57 MPa) and flexural strength (139.2 MPa) were obtained best at 800 r/min rotational speed and 20 s stirring time with 2.5-mm pin depth.
This study investigated the mechanical and tribological properties of 3D-printed Poly (lactic acid) (PLA) composites reinforced with different concentrations of carbon fibers (SCF) and graphene ...nanoparticles (GNP) (0.5 to 5 wt.% of each filler). The samples were produced using FFF (fused filament fabrication) 3D printing. The results showed a good dispersion of the fillers in the composites. SCF and GNP promoted the crystallization of the PLA filaments. The hardness, elastic modulus, and specific wear resistance grew with the increase in the filler concentration. A hardness improvement of about 30% was observed for the composite with 5 wt.% of SCF + 5 wt.% GNP (PSG-5) compared to PLA. The same trend was observed for the elastic modulus with an increase of 220%. All the composites presented lower coefficients of friction (0.49 to 0.6) than PLA (0.71). The composite PSG-5 sample showed the lowest value of specific wear rate (4.04 × 10
mm
/N.m), corresponding to about a five times reduction compared to PLA. Therefore, it was concluded that the addition of GNP and SCF to PLA made it possible to obtain composites with better mechanical and tribological behavior.
Utilizing 3D-printing techniques to fabricate novel composites with multifunctional properties is a real challenge. This study deals with the synthesis of graphitic carbon nitride (g-C
3
N
4
) using ...melamine and reinforcing it with Poly (lactic acid) (PLA) to achieve enhanced mechanical and thermal properties. g-C
3
N
4
is a silane surface modified to increase the bonding strength between filler and matrix. PLA/ g-C
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N
4
composite filament is extruded using a controlled speed of 30 rpm and a temperature of 170 °C, and samples are 3D-printed. To improve mechanical and thermal properties, varying weight percentages (0, 0.5, 1, 3, 5) of g-C
3
N
4
are reinforced into the PLA matrix. The PLA composite (3% filler) exhibited a tensile strength of 62 MPa. The flexural and impact strengths of the composite containing 3% g-C
3
N
4
were 63 MPa and 6.5 KJ/m
2
, respectively. Mechanical properties of 3D printed PLA/g-C
3
N
4
composites were enhanced due to dispersed g-C
3
N
4
filler particles, which shared the stress produced in the polymer and the g-C
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N
4
entrapped the polymer matrix molecular chain. Compared to PLA composite (5% filler) and pure PLA, the initial and final degradation temperatures were increased by about 4.15% and 4.38%, respectively. The thermal properties improved owing to the g-C
3
N
4
particles acting as a thermal barrier in the PLA matrix. Additionally, silane-treated g-C
3
N
4
particles meet the PLA matrix, and the organo-functional group of the silane interacts with the PLA matrix, thus enhancing the interfacial bonding, which restricts the motion of polymer chains at elevated temperatures. The 3D printing process could make them more competitive in the market by making commercial PLA parts that are better for the environment and have better mechanical and thermal properties.
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.
Artificial implants are very essential for the disabled as they are utilized for bone and joint function in orthopedics. However, materials used in such implants suffer from restricted mechanical and ...tribological properties besides the difficulty of using such materials with complex structures. The current study works on developing a new polymer green composite that can be used for artificial implants and allow design flexibility through its usage with 3D printing technology. Therefore, a natural filler extracted from corn cob (CC) was prepared, mixed homogeneously with the Polylactic-acid (PLA), and passed through a complete process to produce a green composite filament suit 3D printer. The corn cob particles were incorporated with PLA with different weight fractions zero, 5%, 10%, 15%, and 20%. The physical, mechanical, and tribological properties of the PLA-CC composites were evaluated. 3D finite element models were constructed to evaluate the PLA-CC composites performance on a real condition implant, hip joints, and through the frictional process. Incorporating corn cob inside PLA revealed an enhancement in the hardness (10%), stiffness (6%), compression ultimate strength (12%), and wear resistance (150%) of the proposed PLA-CC composite. The finite element results of both models proved an enhancement in the load-carrying capacity of the composite. The finite element results came in line with the experimental results.
Frost-retted hemp fibers were investigated to assess their suitability for composite applications. Chemical analysis of frost-retted hemp fibers highlighted a high amount of solubles (pectins) at the ...fibers surface and a low lignin content in the fibers that was attributed to an unfavorable synthesis of lignin in the cell wall due to the particularly cold temperature during hemp growth in the Nordic countries. The fibers tensile properties were considered at two different scales and the performances of hemp/PLA composites were assessed. Recommendations were provided for the use of frost-retted hemp fibers in the reinforcement of thermoplastic composites.
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