Effects of Aging and Infill Pattern on Mechanical Properties of Hemp Reinforced PLA Composite Produced by Fused Filament Fabrication (FFF)

2021 ◽  
Author(s):  
Alperen Dogru ◽  
Ayberk Sozen ◽  
Gokdeniz Neser ◽  
M. Ozgur Seydibeyoglu
Keyword(s):  
Mechanical Properties ◽  
Mass Loss ◽  
Natural Fibers ◽  
Accelerated Aging ◽  
Aging Effect ◽  
Fused Filament Fabrication ◽  
Tensile Direction ◽  
Chemical Treatments ◽  
Tensile Performance ◽  
Effects Of Aging

Reinforcing natural fibers to polymer matrices provides an increase in mechanical properties. In addition, bio composite materials contribute to the sustainable ecosystem with its ease of recyclability. The effect of accelerated aging on the mechanical properties of PLA matrix bio composite specimens has been observed in previous research, but the effect of accelerated aging on the mechanical properties and the resulting mass loss of the material produced with fused filament fabrication (FFF) has been discussed for the first time in this study. Aging was applied to the bio composite consisted of 10% hemp and PLA matrix produced at a constant rate, parallel to the tensile direction and cross (+/– 45°) angle, and the results were examined as tensile stress and mass loss. The aging effect has been observed even from the first week. Specimens with parallel printing to tensile direction showed a lower tensile performance than cross printing one, since the structure in the laminates is quite durable, the adhesion performance in the laminate or through thickness direction has been low. Natural fibers are found so highly hygroscopic that chemical treatments will improve the interface and increase the mechanical properties.

scholarly journals Evaluation of the Deterioration of the Mechanical Properties of Poly(lactic acid) Structures Fabricated by a Fused Filament Fabrication 3D Printer

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 21 ◽  
Author(s):  
Miho Suzuki ◽  
Asahi Yonezawa ◽  
Kohei Takeda ◽  
Akira Yamada
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Tensile Tests ◽  
Poly Lactic Acid ◽  
3D Printer ◽  
Fused Filament Fabrication ◽  
Tensile Direction ◽  
Test Pieces ◽  
3D Printers ◽  
Scan Pattern

A fused filament fabrication (FFF) 3D printer is a simple device capable of manufacturing three-dimensional structures in a series of easy steps. Commercial-level FFF 3D printers have spread rapidly in many fields in recent years. Poly(lactic acid) (PLA) is a biodegradable thermoplastic polymer used as a typical printing medium for FFF 3D printers. The FFF printer constructs an object with melted polymer extruded from a tiny scanning nozzle. The mechanical properties of FFF 3D structures printed with different scan patterns can therefore vary in accordance with the directions from which forces act upon them. The nozzle scan pattern also influences the deterioration of the mechanical properties of the structures in accordance with the degradation caused by the hydrolysis of PLA. In this study we conducted tensile tests to evaluate the strength characteristics of 3D printed test pieces formed from PLA using four different scan patterns: parallel, vertical, parallel-and-vertical, and cross-hatched at opposing diagonal angles to the tensile direction. We also formed test pieces by an injection molding method using the same material, for further comparison. We evaluated the deterioration of the test pieces after immersing them in saline for certain periods. After the test pieces formed by different nozzle scan patterns were immersed, they exhibited differences in the rates by which their maximum tensile stresses deteriorated and their masses increased through water uptake. The influences of the scan patterns could be classified into two types: the unidirectional scan pattern influence and bidirectional scan pattern influence. The data obtained in this research will be applied to structural design when the FFF 3D printer is employed for the fabrication of structures with PLA filament.

scholarly journals Accelerated Aging Effect on Mechanical Properties of Common 3D-Printing Polymers

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4132
Author(s):  
Catalin Gheorghe Amza ◽  
Aurelian Zapciu ◽  
Florin Baciu ◽  
Mihai Ion Vasile ◽  
Adrian Ionut Nicoara
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Structural Changes ◽  
Prolonged Exposure ◽  
Accelerated Aging ◽  
Aging Treatment ◽  
Aging Effect ◽  
Control Group ◽  
Outdoor Environments ◽  
3D Printed

In outdoor environments, the action of the Sun through its ultraviolet radiation has a degrading effect on most materials, with polymers being among those affected. In the past few years, 3D printing has seen an increased usage in fabricating parts for functional applications, including parts destined for outdoor use. This paper analyzes the effect of accelerated aging through prolonged exposure to UV-B on the mechanical properties of parts 3D printed from the commonly used polymers polylactic acid (PLA) and polyethylene terephthalate–glycol (PETG). Samples 3D printed from these materials went through a dry 24 h UV-B exposure aging treatment and were then tested against a control group for changes in mechanical properties. Both the tensile and compressive strengths were determined, as well as changes in material creep characteristics. After irradiation, PLA and PETG parts saw significant decreases in both tensile strength (PLA: −5.3%; PETG: −36%) and compression strength (PLA: −6.3%; PETG: −38.3%). Part stiffness did not change significantly following the UV-B exposure and creep behavior was closely connected to the decrease in mechanical properties. A scanning electron microscopy (SEM) fractographic analysis was carried out to better understand the failure mechanism and material structural changes in tensile loaded, accelerated aged parts.

Effect of Pretreatment Methods on Properties of Natural Fiber Composites: A Review

2016 ◽  
Vol 24 (7) ◽  
pp. 555-566 ◽  
Author(s):  
N. Venkatachalam ◽  
P. Navaneethakrishnan ◽  
R. Rajsekar ◽  
S. Shankar
Keyword(s):  
Mechanical Properties ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Agricultural Waste ◽  
Research Work ◽  
Natural Fibers ◽  
Synthetic Fiber ◽  
Fiber Reinforced ◽  
Chemical Treatments

India as a tropical agricultural country has great potential to develop and use fiber derived from agricultural waste. Natural fibers are an important by-product of extraction process and they can be used as reinforcement in composite products. Composites are developed with unsaturated polyester resin as the matrix with natural fiber as the reinforcement. The results show decreased strength and modulus with increasing the fiber volume fraction. This indicates ineffective stress transfer between the fiber and matrix due to lower adhesion. It is necessary to bring a hydrophobic nature to the fibers by suitable chemical treatments in order to develop composites with improved mechanical properties. In these review papers, different types of natural fibers are subjected to a variety of physical and chemical treatments. The types of treatments studied in these papers include Physical treatments such as beating and heating, and chemical treatments like alkalization, silane, acetylation and benzoylation. The effects of these treatments on mechanical properties of the composites are analyzed. Fractures are analyzed by using the scanning electron microscopy (SEM). Analysis by FTIR and DMA showed that physico-chemical changes of surfaces of treated natural fibers. In general, treatments to the fibers can significantly improve adhesion and reduce water absorption, thereby improving mechanical properties of the composites. The purpose of this review paper is to summarize the research work done on various pretreatments in the preparation of natural fiber reinforced composites and to highlight the potential use of natural fiber reinforced polymer composites in industry and its potential to replace the synthetic fiber composite and conventional materials in the future.

Effect of Chemical Treatment on Mechanical Properties of Banana and Abaca Fiber Reinforced Composites

2015 ◽  
Vol 813-814 ◽  
pp. 25-29 ◽  
Author(s):  
B. Krishnakumar ◽  
T. Panneerselvam ◽  
S. Raghuraman
Keyword(s):  
Mechanical Properties ◽  
Chemical Treatment ◽  
Moisture Absorption ◽  
Natural Fibers ◽  
High Strength ◽  
Chemical Treatments ◽  
Polymer Resin ◽  
Untreated Fiber ◽  
Low Weight ◽  
Treated Fiber

In materials industries, composite is an emerging material known for its low weight - high strength. The composite is a material that contains two different phases in order to create particular properties. The synthetic composites require a large quantum of energy and also the environment is being affected due to the pollution generated during the production and recycling. This draws the attention to use natural fibers as it is lower in cost and biodegradable. In this work, the chemical treatments of the banana and abaca natural fibers are carried out to modify the surface, stop the moisture absorption and improves the adhesion. The chemical treatment is carried out for both fibers separately in 10% concentrated sodium hydroxide for a duration of five hours and 5% concentrated potassium permanganate for a duration of two hours. The composite materials are fabricated using treated fiber and untreated fiber individually with general polymer resin by the hand lay-up process. The fabricated composites are tested to evaluate mechanical properties such as tensile, impact and flexural strength as per the ASTM standards. The mechanical properties of the treated fiber and untreated fiber are compared and it is found that the mechanical properties have been significantly improved due to the chemical treatment.

scholarly journals Mechanical Properties of Mortars Reinforced with Amazon Rainforest Natural Fibers

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 155
Author(s):  
Régis Pamponet da Fonseca ◽  
Janaíde Cavalcante Rocha ◽  
Malik Cheriaf
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Natural Fibers ◽  
Construction Materials ◽  
Hot Water ◽  
Amazon Rainforest ◽  
Hot Water Treatment ◽  
Composite Binder ◽  
Naoh Solution ◽  
Reference Samples

The addition of natural fibers used as reinforcement has great appeal in the construction materials industry since natural fibers are cheaper, biodegradable, and easily available. In this work, we analyzed the feasibility of using the fibers of piassava, tucum palm, razor grass, and jute from the Amazon rainforest as reinforcement in mortars, exploiting the mechanical properties of compressive and flexural strength of samples with 1.5%, 3.0%, and 4.5% mass addition of the composite binder (50% Portland cement + 40% metakaolin + 10% fly ash). The mortars were reinforced with untreated (natural) and treated (hot water treatment, hornification, 8% NaOH solution, and hybridization) fibers, submitted to two types of curing (submerged in water, and inflated with CO2 in a pressurized autoclave) for 28 days. Mortars without fibers were used as a reference. For the durability study, the samples were submitted to 20 drying/wetting cycles. The fibers improved the flexural strength of the mortars and prevented the abrupt rupture of the samples, in contrast to the fragile behavior of the reference samples. The autoclave cure increased the compressive strength of the piassava and tucum palm samples with 4.5% of fibers.

scholarly journals The Structure and Mechanical Properties of Hemp Fibers-Reinforced Poly(ε-Caprolactone) Composites Modified by Electron Beam Irradiation

2021 ◽  
Vol 11 (12) ◽  
pp. 5317
Author(s):  
Rafał Malinowski ◽  
Aneta Raszkowska-Kaczor ◽  
Krzysztof Moraczewski ◽  
Wojciech Głuszewski ◽  
Volodymyr Krasinskyi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Electron Beam ◽  
Impact Strength ◽  
Flexural Modulus ◽  
Natural Fibers ◽  
High Energy ◽  
Electron Radiation ◽  
Elongation At Break ◽  
Hemp Fibers

The need for the development of new biodegradable materials and modification of the properties the current ones possess has essentially increased in recent years. The aim of this study was the comparison of changes occurring in poly(ε-caprolactone) (PCL) due to its modification by high-energy electron beam derived from a linear electron accelerator, as well as the addition of natural fibers in the form of cut hemp fibers. Changes to the fibers structure in the obtained composites and the geometrical surface structure of sample fractures with the use of scanning electron microscopy were investigated. Moreover, the mechanical properties were examined, including tensile strength, elongation at break, flexural modulus and impact strength of the modified PCL. It was found that PCL, modified with hemp fibers and/or electron radiation, exhibited enhanced flexural modulus but the elongation at break and impact strength decreased. Depending on the electron radiation dose and the hemp fibers content, tensile strength decreased or increased. It was also found that hemp fibers caused greater changes to the mechanical properties of PCL than electron radiation. The prepared composites exhibited uniform distribution of the dispersed phase in the polymer matrix and adequate adhesion at the interface between the two components.

scholarly journals Effect of Accelerated Aging on Some Mechanical Properties and Wear of Different Commercial Dental Resin Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2769
Author(s):  
Jonne Oja ◽  
Lippo Lassila ◽  
Pekka K. Vallittu ◽  
Sufyan Garoushi
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Accelerated Aging ◽  
Wear Depth ◽  
Resin Composites ◽  
Expiration Date ◽  
Dental Resin ◽  
Hydrothermal Aging ◽  
Dental Resin Composites

The aim of current in vitro research was to determine the effect of hydrothermal accelerated aging on the mechanical properties and wear of different commercial dental resin composites (RCs). In addition, the effect of expiration date of the composite prior its use was also evaluated. Five commercially available RCs were studied: Conventional RCs (Filtek Supreme XTE, G-aenial Posterior, Denfil, and >3y expired Supreme XTE), bulk-fill RC (Filtek Bulk Fill), and short fiber-reinforced RC (everX Posterior). Three-point flexural test was used for determination of ultimate flexural strength (n = 8). A vickers indenter was used for testing surface microhardness. A wear test was conducted with 15,000 chewing cycles using a dual-axis chewing simulator. Wear pattern was analyzed by a three-dimensional (3D) noncontact optical profilometer. Degree of C=C bond conversion of monomers was determined by FTIR-spectrometry. The specimens were either dry stored for 48 h (37 °C) or boiled (100 °C) for 16 h before testing. Scanning electron microscopy (SEM) was used to evaluate the microstructure of each material. Data were analyzed using ANOVA (p = 0.05). Hydrothermal aging had no significant effects on the surface wear and microhardness of tested RCs (p > 0.05). While flexural strength significantly decreased after aging (p < 0.05), except for G-aenial Posterior, which showed no differences. The lowest average wear depth was found for Filtek Bulk Fill (29 µm) (p < 0.05), while everX Posterior and Denfil showed the highest wear depth values (40, 39 µm) in both conditions. Passing the expiration date for 40 months did not affect the flexural strength and wear of tested RC. SEM demonstrated a significant number of small pits on Denfil’s surface after aging. It was concluded that the effect of accelerated aging may have caused certain weakening of the RC of some brands, whereas no effect was found with one brand of RC. Thus, the accelerated aging appeared to be more dependent on material and tested material property.

scholarly journals Valorization of Invasive Plants from Macaronesia as Filler Materials in the Production of Natural Fiber Composites by Rotational Molding

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2220
Author(s):  
Zaida Ortega ◽  
Francisco Romero ◽  
Rubén Paz ◽  
Luis Suárez ◽  
Antonio Nizardo Benítez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Invasive Plant ◽  
Natural Fiber ◽  
Ricinus Communis ◽  
Local Level ◽  
Natural Fibers ◽  
Fiber Composites ◽  
Filler Materials ◽  
Natural Fiber Composites ◽  
Rotational Molding

This paper compares the mechanical properties of different natural fiber composites produced by rotational molding as a way of waste valorization from campaigns to control invasive plant species in Macaronesia. Rotomolded parts produced with polymeric matrices (polyethylene) and filled with up to 20% by weight of cellulosic fibers obtained from Arundo donax L., Pennisetum setaceum, and Ricinus communis plants were characterized in terms of tensile, flexural, and impact strength. It was found that the sieving of natural fibers allowed for their introduction in higher loadings, from 10 (for un-sieved material) to 20%; fiber size greatly affected the mechanical properties of the final parts, although some combinations were proven not to reduce the mechanical properties of the neat resin. This study is a first approach to the valorization of residues obtained from periodic campaigns of the control of invasive species performed by public authorities, usually at the local level. It is important to highlight that the main objective of this research did not focus on economically profitable activity; instead, it was focused on the reduction of wastes to be disposed from ecosystem maintenance actions and the investment of potential income into preservation policies.

scholarly journals Effects of Aging under Stress on Mechanical Properties and Microstructure of EN AW 7075 Alloy

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1142
Author(s):  
S. V. Sajadifar ◽  
P. Krooß ◽  
H. Fröck ◽  
B. Milkereit ◽  
O. Kessler ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Screening Tool ◽  
Precipitation Kinetics ◽  
Scanning Calorimetry ◽  
Aging Precipitation ◽  
Precipitation Processes ◽  
External Stresses ◽  
7075 Alloy ◽  
Effects Of Aging

In the present study, microstructural and mechanical properties of EN AW 7075 following stress-aging were assessed. For this purpose, properties of stress-aged samples were compared with values obtained for conventionally aged counterparts. It is revealed that the strength and hardness of EN AW 7075 can be increased by the presence of external stresses during aging. Precipitation kinetics were found to be accelerated. The effects of conventional and stress-aging on the microstructure were analyzed using synergetic techniques: the differently aged samples were probed by differential scanning calorimetry (DSC) in order to characterize the precipitation processes. DSC was found to be an excellent screening tool for the analysis of precipitation processes during aging of this alloy with and without the presence of external stresses. Furthermore, using electron microscopy it was revealed that an improvement in mechanical properties can be correlated to changes in the morphologies and sizes of precipitates formed.

scholarly journals Evaluation of the influence of design in the mechanical properties of honeycomb cores used in composite panels

2021 ◽  
pp. 146442072098519
Author(s):  
A Miranda ◽  
M Leite ◽  
L Reis ◽  
E Copin ◽  
MF Vaz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Failure Modes ◽  
Industrial Applications ◽  
Sandwich Composite ◽  
Composite Panels ◽  
Distribution Analysis ◽  
Absorbed Energy ◽  
Fused Filament Fabrication ◽  
Subtractive Manufacturing

The aerospace, automotive, and marine industries are heavily reliant on sandwich panels with cellular material cores. Although honeycombs with hexagonal cells are the most commonly used geometries as cores, recently there have been new alternatives in the design of lightweight structures. The present work aims to evaluate the mechanical properties of metallic and polymeric honeycomb structures, with configurations recently proposed and different in-plane orientations, produced by additive and subtractive manufacturing processes. Structures with configurations such as regular hexagonal honeycomb (Hr), lotus (Lt), and hexagonal honeycomb with Plateau borders (Pt), with 0°, 45°, and 90° orientations were analyzed. To evaluate its properties, three-point bending tests were performed, both experimentally and by numerical modeling, by means of the finite element method. Honeycombs of two aluminum alloys and polylactic acid were fabricated. The structures produced in aluminum were obtained either by selective laser melting technology or by machining, while polylactic acid structures were obtained by material extrusion using fused filament fabrication. From the stress distribution analysis and the load–displacement curves, it was possible to evaluate the strength, stiffness, and absorbed energy of the structures. Failure modes were also analyzed for polylactic acid honeycombs. In general, a strong correlation was observed between numerical and experimental results. The results show that the stiffness and absorbed energy increase in the order, Hr, Pt, Lt, and with the orientation through the sequence, 45°, 90°, 0°. Thus, Lt structures with 0° orientation seem to be good alternatives to the traditional honeycombs used in sandwich composite panels for those industrial applications where low weight, high stiffness, and large energy-absorbing capacity are required.

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