Search results for: polylactic acid particles

Authors: Feng Ju Chuang, Yu Wen Wang, Tai Jung Hsieh, Shyh Ming Kuo

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Polylactic acid is a synthetic polymer with good biocompatibility and degradability, is widely used in clinical applications. In this study, we utilized Polylactic acid particles as stimulants for macrophages and the collagen synthesis of co-cultured fibroblasts was evaluated. The results indicated that Polylactic acid particles were nontoxic to cells from 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. No obvious inflammation effect was observed (under the PLLA concentration of 1 mg/mL) after 24-h co-culture of Raw264.7 and NIH3T3 cells (from TNF-α assay). The addition of PLLA particles to the Raw264.7 and NIH3T3 co-cultures increased the synthesis of collagen, the highest collagen synthesis from the fibroblast was the 0.2 mg/mL (approximately 60% increased as compared with without addition Polylactic acid particles). Moreover, a co-axial atomization delivery device was used to percutaneously introduce Polylactic acid particles into the dermis layer and stimulating macrophages to secrete growth factors promoting fibroblasts to produce collagen. The preliminary results demonstrated the synthesis of collagen was increased mildly after the introduction of Polylactic acid particles for 28-d post implantation. The Polylactic acid particles could be successfully introduced into the dermis layer from H&E staining examination, however, the optimum concentration of Polylactic acid particles and the time-period for collagen synthesis still need to be evaluated.

Keywords: collagen synthesis, macrophage, NIH3T3 cells, polylactic acid particles

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Authors: Qasar Saleem

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The aim of this project was to synthesize and analyze Polylactic acid-grafted TiO2 nanocomposite. When dispersed at the nanoscale TiO2 can behave as see through transparent UV filters and thermomechanical materials. The synthesis plan involved three stages. First, dispersion of TiO2 white powder in water/ethanol solvent system. Second grafting TiO2 surface by oligomers of lactic acid aimed at changing its surface features. Third polymerization of lactic acid monomer with grafted TiO2 in the presence of anhydrous stannous chloride as a catalyst. Polylactic acid grafted-TiO2 nanocomposite was synthesized by melt polycondensation in situ of lactic acid onto titanium oxide (TiO2) nanoparticles surface. The product was characterized by TGA, DSC, FTIR, and UV analysis and degradation observation. An idea regarding bonds between the grafting polymer and surface modified titanium oxide nanoparticles. Characteristics peaks of Ti–carbonyl bond, the related intensities of the Fourier transmission absorption peaks of graft composite, the melt and decomposition behavior stages of Polylactic acid-grafted TiO2 nanocomposite convinced that oligomers of polylactic acid were chemically bonded on the surface of TiO2 nanoparticles. Through grafting polylactic acid, the Polylactic acid grafted -TiO2 sample shown good absorption in UV region and degradation behavior under normal atmospheric conditions. Regaining transparency of degraded white opaque Polylactic acid-grafted TiO2 nanocomposite on heating was another character. Polylactic acid-grafted TiO2 nanocomposite will be a potential candidate in future for biomedical, UV shielding and environment friendly material.

Keywords: condensation, nanocomposites, oligomers, polylactic

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Authors: Fathilahbinti Ali, Jamarosliza Jamaluddin, Arun Kumar Upadhyay

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Poly(lactic acid) (PLA) is a biodegradable polymer which has good mechanical properties, however, its brittleness limits its usage especially in packaging materials. Therefore, in this work, PLA based polyurethane films were prepared by synthesizing with different types of isocyanates; methylene diisocyanate (MDI) and hexamethylene diisocyanates (HDI). For this purpose, PLA based polyurethane must have good strength and flexibility. Therefore, polycaprolactone which has better flexibility were prepared with PLA. An effective way to endow polylactic acid with toughness is through chain-extension reaction of the polylactic acid pre-polymer with polycaprolactone used as chain extender. Polyurethane prepared from MDI showed brittle behaviour, while, polyurethane prepared from HDI showed flexibility at same concentrations.

Keywords: biodegradable polymer, flexible, poly(lactic acid), polyurethane

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Authors: Hamad Al-Turaif, Usman Saeed

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The development of nanofibers with the help of electrospinning is being prioritized as a method of choice because of the simplicity and efficiency of the process. The parameters of the electrospinning process effectively convert the polymer solution into an electrospun final product made of the desired diameter of nanofiber. The aim of the study presented is to recognize and analyze the effect of proposed parameters on biodegradable and biocompatible polylactic acid (PLA)/polybutylene succinate (PBS) nanofiber developed by the electrospinning process. The morphology of the fiber is characterized by implementing Scanning Electron Microscope. Studies were conducted to characterize the result of using different electrospinning parameters on the final diameter and orientation of fiber. It was determined that varying polymer solution concentration, feed rate, and applied voltage show different outcomes. The best results were obtained at 6% polymer solution concentration, 20 kV, and 0.5 ml/h, which can be applicable for biomedical applications. Finally, protein adsorption and mechanical testing were conducted on the PLA/PBS fiber.

Keywords: electrospinning, polylactic acid, polybutylene succinate, morphology

Procedia PDF Downloads 75

Authors: A. Bárbara Cattozatto Fortunato, D. de Lucca Soave, E. Pinheiro de Mello, M. Piasentini Oliva, V. Tavares de Moraes, G. Wolf Lebrão, D. Fernandes Parra, S. Marraccini Giampietri Lebrão

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Due to increasing environmental pressure for biodegradable products, especially in polymeric materials, in order to meet the demands of the biological cycles of the circular economy, new materials have been developed as a sustainability strategy. This study proposes a composite material developed from the biodegradable polymer PLA Ecovio® (polylactic acid - PLA) with natural sisal fibers, where the soybean ester was used as a plasticizer, which can aid in adhesion between the materials and fibers, making the most attractive final composite from an environmental point of view. The composites were obtained by extrusion. The materials tests were produced and submitted to biodegradation tests. Through the biodegradation tests, it can be seen that the biodegradable polymer composition with 5% sisal fiber presented about 12.4% more biodegradability compared to the polymer without fiber addition. It has also been found that the plasticizer was not a compatible with fibers and the polymer. Finally, fibers help to anticipate the decomposition process of the material when subjected to conditions of a landfill. Therefore, its intrinsic properties are not affected during its use, only the biodegradation process begins after its exposure to landfill conditions.

Keywords: biocomposites, sisal, polilactic acid, Polylactic Acid (PLA)

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Authors: G. K. Awari, Vishwajeet V. Ambade, S. W. Rajurkar

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The field of additive manufacturing is growing, and discoveries are being made. 3D printing machines are also being developed to accommodate a wider range of 3D printing materials, including plastics, metals (metal AM powders), composites, filaments, and other materials. There are numerous printing materials available for industrial additive manufacturing. Such materials have their unique characteristics, advantages, and disadvantages. In order to avoid errors in additive manufacturing, key elements such as 3D printing material type, texture, cost, printing technique and procedure, and so on must be examined. It can be complex to select the best material for a particular job. Polylactic acid (PLA) is made from sugar cane or cornstarch, both of which are renewable resources. "Black plastic" is another name for it. Because it is safe to use and print, it is frequently used in primary and secondary schools. This is also how FDM screen printing is done. PLA is simple to print because of its low warping impact. It's also possible to print it on a cold surface. When opposed to ABS, it allows for sharper edges and features to be printed. This material comes in a wide range of colours. Polylactic acid (PLA) is the most common material used in fused deposition modelling (FDM). PLA can be used to print a wide range of components, including medical implants, household items, and mechanical parts. The mechanical behaviour of the printed item is affected by variations in infill patterns that are subjected to compressive tests in the current investigation to examine their behaviour under compressive stresses.

Keywords: fused deposition modelling, polylactic acid, infill density, infill pattern, compressive strength

Procedia PDF Downloads 43

Authors: M. S. E. Hamroun, K. Bachari, A. Berrayah, L. Mechernene, L. Guerbous

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Composite films containing homogeneously dispersed scintillation nano-particles of Lu₂SiO₅:Ce³⁺, in optically transparent polymer matrix, have been prepared and characterized through X-ray diffraction, differential scanning calorimetric (DSC), thermogravimetric analysis (ATG), dynamic mechanical analysis (DMA), electron scanning microscopy morphology (SEM) and photoluminescence (PL). Lu₂SiO₅:Ce³⁺ scintillator powder was successfully synthesized via Sol-Gel method. This study is realized with different mass ratios of nano-particles embedded in polystyrene and polylactic acid polymer matrix (5, 10, 15, 20%) to see the influence of nano-particles on the mechanical, structural and optical properties of films. The composites have been prepared with 400 µm thickness. It has found that the structural proprieties change with mass ratio on each sample. PL photoluminescence shows the characteristic Lu₂SiO₅:Ce³⁺ emission in the blue region and intensity varied for each film.

Keywords: nano-particles, sol gel, photoluminescence, Ce³⁺, scintillator, polystyrene

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Authors: Daniel Tarrazó-Serrano, Sergio Pérez-López, Sergio Castiñeira-Ibáñez, Pilar Candelas, Constanza Rubio

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Zone Plates (ZPs) are used in many areas of physics where planar fabrication is advantageous in comparison with conventional curved lenses. There are several types of ZPs, such as the well-known Fresnel ZPs or the more recent Fractal ZPs and Fibonacci ZPs. The material selection of the lens plays a very important role in the beam modulation control. This work presents a comparison between two Fresnel ZP made from different materials in the ultrasound domain: Polylactic Acid (PLA) and brass. PLA is the most common material used in commercial 3D-printers due to its high design flexibility and low cost. Numerical simulations based on Finite Element Method (FEM) and experimental results are shown, and they prove that the focusing capabilities of brass ZPs and PLA ZPs are similar. For this reason, PLA is proposed as a Magnetic Resonance Imaging (MRI) compatible material with great potential for therapeutic ultrasound focusing applications.

Keywords: FZP, PLA, focus, ultrasound, MRI

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Authors: Mingchuan Zhou, Haitao Zhang, Hongfang Ma, Weiyong Ying

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Alumina supported PtSn catalysts with cylindrical particles were prepared and characterized by using low temperature N2 adsorption/desorption and X-ray diffraction. Low temperature N2 adsorption/desorption demonstrate that the tableting changed the texture properties of catalysts. XRD pattern indicate that the crystal structure of supports had no change after reaction. The performances over particles of PtSn/Al2O3 catalysts were investigated with regards to reaction temperature, pressure, and H2/AcOH mole ratio. After tableting, the conversion of acetic acid and selectivity of ethanol and acetyl acetate decreased. High reaction temperature and pressure can improve conversion of acetic acid. H2/AcOH mole ratio of 9.36 showed the best performance on acetic acid hydrogenation. High pressure had benefits for the selectivity of ethanol and other two parameters had no obvious effect on selectivity.  

Keywords: acetic acid hydrogenation, cylindrical particles, ethanol, PtSn

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Authors: Sónia Ribeiro, Diana Farinha, Hélia Sales, Rita Pontes, João Nunes

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The demand and commitment to sustainability in the agrifood sector introduce news opportunities for new composite materials. Composite materials are emerging as a vital entity for the sustainable development. Polylactic acid (PLA) has been recognized as a potential polymer with attractive characteristics for agrifood sector applications. PLA that can be beneficial for the development of composites, biocomposites, films, porous gels, and so on. The production of PLA from lignocellulosic biomass residues matrix is a key option towards a sustainable and circular bioeconomy and a non-competitive application with feed and food sector. The Flui and BeirInov projects presents news developments in the production of PLA composites to value the Portuguese forest ecosystem, with high amount of lignocellulosic biomass residues and available. A performance production of lactic acid from lignocellulosic biomass undergoes a process of autohydrolysis, saccharification and fermentation, originating a lactic acid fermentation medium with a 72.27g.L-1 was obtained and a final purification of 72%. The high purification PLA from multi lignocellulosic residues representing one economic expensive process, and a new materials and application for the polymers and a combination with others types of composites matrix characteristic is the drive-up for this green market.

Keywords: polylactic acid, lignocellulosic biomass, agrifood, composite materials

Procedia PDF Downloads 45

Authors: Amir Doustgani

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Melt electrospinning is a safe and simple technique for the production of micro and nanofibers which can be an alternative to conventional solvent electrospinning. The effects of various melt-electrospinning parameters, including molecular weight, electric field strength, flow rate and temperature on the morphology and fiber diameter of polylactic acid were studied. It was shown that molecular weight was the predominant factor in determining the obtainable fiber diameter of the collected fibers. An orthogonal design was used to examine process parameters. Results showed that molecular weight is the most effective parameter on the average fiber diameter of melt electrospun PLA nanofibers and the flow rate has the less important impact. Mean fiber diameter increased by increasing MW and flow rate, but decreased by increasing electric field strength and temperature. MFD of optimized fibers was below 100 nm and the result of software was in good agreement with the experimental condition.

Keywords: fiber formation, processing, spinning, melt blowing

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Authors: J. H. O. Nascimento, F. R. Oliveira, K. K. O. S. Silva, J. Neves, V. Teixeira, J. Carneiro

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These the aliphatic polyesters such as Polylactic Acid (PLA) in the form of fibers, nanofibers or plastic films, generally possess chemically inert surfaces, free porosity, and surface free energy (ΔG) lesser than 32 mN/m. It is therefore considered a low surface energy material, consequently has a low work of adhesion. For this reason, the products manufactured using these polymers are often subjected to surface treatments in order to change its physic-chemical surface, improving their wettability and the Work of Adhesion (WA). Plasma Radio Frequency low pressure (RF) treatment was performed in order to improve the Work of Adhesion (WA) on PLA fibers. Different parameters, such as, power, ratio of working gas (Argon/Oxygen) and treatment time were used to optimize the plasma conditions to modify the PLA surface properties. With plasma treatment, a significant increase in the work of adhesion on PLA fiber surface was observed. The analysis performed by XPS showed an increase in polar functional groups and the SEM and AFM image revealed a considerable increase in roughness.

Keywords: RF plasma, surface modification, PLA fabric, atomic force macroscopic, Nanotechnology

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Authors: Ala Abobakr Abdulhafidh Al-Dubai

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Bone loss has risen due to fractures, surgeries, and traumatic injuries. Scientists and engineers have worked over the years to find solutions to heal and accelerate bone regeneration. The bone grafting technique has been utilized, which projects significant improvement in the bone regeneration area. An extensive study is essential on the relation between the mechanical properties of bone scaffolds and the pore size of the scaffolds, as well as the relation between the mechanical properties of bone scaffolds with the development of bioactive coating on the scaffolds. In reducing the cost and time, a mechanical simulation analysis is beneficial to simulate both relations. Therefore, this study highlights the simulated mechanical analyses on three-dimensional (3D) polylactic acid (PLA) scaffolds at two different pore sizes (P: 400 and 600 μm) and two different internals distances of (D: 600 and 900 μm), with and without the presence of hydroxyapatite (HA) coating. The 3D scaffold models were designed using SOLIDWORKS software. The respective material properties were assigned with the fixation of boundary conditions on the meshed 3D models. Two different loads were applied on the PLA scaffolds, including side loads of 200 N and vertical loads of 2 kN. While only vertical loads of 2 kN were applied on the HA coated PLA scaffolds. The PLA scaffold P600D900, which has the largest pore size and maximum internal distance, generated the minimum stress under the applied vertical load. However, that same scaffold became weaker under the applied side load due to the high construction gap between the pores. The development of HA coating on top of the PLA scaffolds induced greater stress generation compared to the non-coated scaffolds which is tailorable for bone implantation. This study concludes that the pore size and the construction of HA coating on bone scaffolds affect the mechanical strength of the bone scaffolds.

Keywords: hydroxyapatite coating, bone scaffold, mechanical simulation, three-dimensional (3D), polylactic acid (PLA).

Procedia PDF Downloads 22

Authors: Camila Hurtado, Maria A. Morales, Diego Torres, L.H. Reyes, Alejandro Maranon, Alicia Porras

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This work presents the physical and chemical characterization of beer brand fibers and the properties of novel composite materials made of these fibers and polylactic acid (PLA). Treated and untreated fibers were physically characterized in terms of their moisture content (ASTM D1348), density, and particle size (ASAE S319.2). A chemical analysis following TAPPI standards was performed to determine ash, extractives, lignin, and cellulose content on fibers. Thermal stability was determined by TGA analysis, and an FTIR was carried out to check the influence of the alkali treatment in fiber composition. An alkali treatment with NaOH (5%) of fibers was performed for 90 min, with the objective to improve the interfacial adhesion with polymeric matrix in composites. Composite materials based on either treated or untreated beer brand fibers and polylactic acid (PLA) were developed characterized in tension (ASTM D638), bending (ASTM D790) and impact (ASTM D256). Before composites manufacturing, PLA and brand beer fibers (10 wt.%) were mixed in a twin extruder with a temperature profile between 155°C and 180°C. Coupons were manufactured by compression molding (110 bar) at 190°C. Physical characterization showed that alkali treatment does not affect the moisture content (6.9%) and the density (0.48 g/cm³ for untreated fiber and 0.46 g/cm³ for the treated one). Chemical and FTIR analysis showed a slight decrease in ash and extractives. Also, a decrease of 47% and 50% for lignin and hemicellulose content was observed, coupled with an increase of 71% for cellulose content. Fiber thermal stability was improved with the alkali treatment at about 10°C. Tensile strength of composites was found to be between 42 and 44 MPa with no significant statistical difference between coupons with either treated or untreated fibers. However, compared to neat PLA, composites with beer bran fibers present a decrease in tensile strength of 27%. Young modulus increases by 10% with treated fiber, compared to neat PLA. Flexural strength decreases in coupons with treated fiber (67.7 MPa), while flexural modulus increases (3.2 GPa) compared to neat PLA (83.3 MPa and 2.8 GPa, respectively). Izod impact test results showed an improvement of 99.4% in coupons with treated fibers - compared with neat PLA.

Keywords: beer bran, characterization, green composite, polylactic acid, surface treatment

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Authors: Z. Ansari, M. R. M. Rejab, D. Bachtiar, J. P. Siregar

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This study focus on the compression and tensile properties of new and recycle square honeycombs structure from sugar palm fibre (SPF) and polylactic acid (PLA) composite. The end data will determine the failure strength and energy absorption for both new and recycle composite. The control SPF specimens were fabricated from short fibre co-mingled with PLA by using a bra-blender set at 180°C and 50 rpm consecutively. The mixture of 30% fibre and 70% PLA were later on the hot press at 180°C into sheets with thickness 3mm consecutively before being assembled into a sandwich honeycomb structure. An INSTRON tensile machine and Abaqus 6.13 software were used for mechanical test and finite element simulation. The percentage of error from the simulation and experiment data was 9.20% and 9.17% for both new and recycled product. The small error of percentages was acceptable due to the nature of the simulation model to be assumed as a perfect model with no imperfect geometries. The energy absorption value from new to recycled product decrease from 312.86kJ to 282.10kJ. With this small decrements, it is still possible to implement a recycle SPF/PLA composite into everyday usages such as a car's interior or a small size furniture.

Keywords: failure modes, numerical modelling, polylactic acid, sugar palm fibres

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Authors: Anis A. Ansari, M. Kamil

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The development of 3D printing technology has allowed the manufacturing industry to create parts with a high degree of automation, increased design freedom, and improved mechanical performance. Fused deposition modelling (FDM) is a 3D printing technique in which successive layers of thermoplastic polymer are deposited and controlled to create a three-dimensional product. In this study, process parameters such as nozzle temperature and printing speed were chosen to investigate their effects on hardness properties. 3D printed specimens were fabricated by an FDM 3D printer from Polylactic acid (PLA) polymer. After analysis, it was observed that the hardness property is much influenced by print speed and nozzle temperature parameters. Maximum hardness was achieved at higher print speed which indicates that the Shore D hardness is directly proportional to the print speed. Moreover, at higher print speed, it has no significant dependence on the nozzle temperature. Hardness is also influenced by nozzle temperature, though to a lesser extent. The hardness slightly lowers when the nozzle temperature is raised from 190 to 210 oC, but due to improved bonding between each raster, a further rise in temperature increases the hardness property.

Keywords: 3D printing, fused deposition modeling (FDM), polylactic acid (PLA), print speed, nozzle temperature, hardness property

Procedia PDF Downloads 58

Authors: Gansukh Erdenedelger, Doljinsuren Sukhbaatar, Trung Dung Dao, Byeong-Kyu Lee, Han Mo Jeong

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Two kinds of carboxylated thermally reduced graphenes (C-TRGs) having different lateral sizes are examined as a Pickering stabilizer in the suspension polymerization of methyl methacrylate. The size and the shape of the prepared composite particles are irregular due to agglomeration, more evidently when the larger C-TRG is used. In addition, C-TRG is distributed not only on the surface but also inside the composite particles. It indicates that the C-TRG alone is not a stable Pickering agent. However, a very small dosage of acrylic acid remedies all these issues, because acrylic acid interacts with C-TRG and synergizes the stabilizing effect. The compression molded composite of the core/shell poly(methyl methacrylate)/C-TRG particles exhibits a very low percolation threshold of electrical conductivity of 0.03 vol%. It demonstrates that the C-TRG shells of the composite particles effectively form a segregated conductive network throughout the composite.

Keywords: pickering, graphene, polymerization, PMMA

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Authors: Sukhila Krishnan, Smita Mohanty, Sanjay K. Nayak

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Polylactide (PLA) and thermoplastic starch (TPS) are the most promising bio-based materials presently available on the market. Polylactic acid is one of the versatile biodegradable polyester showing wide range of applications in various fields and starch is a biopolymer which is renewable, cheap as well as extensively available. The usual increase in the cost of petroleum-based commodities in the next decades opens bright future for these materials. Their biodegradability and compostability was an added advantage in applications that are difficult to recycle. Currently, thermoplastic starch (TPS) has been used as a substitute for synthetic plastic in several commercial products. But, TPS shows some limitations mainly due to its brittle and hydrophilic nature, which has to be resolved to widen its application.The objective of the work we report here was to initiate chemical modifications on TPS and to build up a process to control its chemical structure using a solution process which can reduce its water sensitive properties and then blended it with PLA to improve compatibility between PLA and TPS. The method involves in cleavage of starch amylose and amylopectin chain backbone to plasticize with glycerol and water in batch mixer and then the prepared TPS was reacted in solution with diisocyanates i.e, 4,4'-Methylenediphenyl Diisocyanate (MDI).This diisocyanate was used before with great success for the chemical modification of TPS surface. The method utilized here will form an urethane-linkages between reactive isocyanate groups (–NCO) and hydroxyl groups (-OH) of starch as well as of glycerol. New polymer synthesised shows a reduced crystallinity, less hydrophilic and enhanced compatibility with other polymers. The TPS was prepared by Haake Rheomix 600 batch mixer with roller rotors operating at 50 rpm. The produced material is then refluxed for 5hrs with MDI in toluene with constant stirring. Finally, the modified TPS was melt blended with PLA in different compositions. Blends obtained shows an improved mechanical properties. These materials produced are characterized by Fourier Transform Infrared Spectra (FTIR), DSC, X-Ray diffraction and mechanical tests.

Keywords: polylactic acid, thermoplastic starch, Methylenediphenyl Diisocyanate, Polylactide (PLA)

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Authors: Nurul Aqilah Mohd Zaini, Afroditi Chatzifragkou, Dimitris Charalampopoulos

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D-Lactic acid production is gaining increasing attention due to the thermostable properties of its polymer, Polylactic Acid (PLA). In this study, D-lactic acid was produced in microbial cultures using Lactobacillus coryniformis subsp. torquens as D-lactic acid producer and hydrolysates of Dried Distillers Grains with Solubles (DDGS) as fermentation substrate. Prior to fermentation, DDGS was first alkaline pretreated with 5% (w/v) NaOH, for 15 minutes (121oC/ ~16 psi). This led to the generation of DDGS solid residues, rich in carbohydrates and especially cellulose (~52%). The carbohydrate-rich solids were then subjected to enzymatic hydrolysis with Accellerase® 1500. For Separate Hydrolysis and Fermentation (SHF), enzymatic hydrolysis was carried out at 50oC for 24 hours, followed by fermentation of D-lactic acid at 37oC in controlled pH 6. The obtained hydrolysate contained 24 g/l glucose, 5.4 g/l xylose and 0.6 g/l arabinose. In the case of Simultaneous Saccharification and Fermentation (SSF), hydrolysis and fermentation were conducted in a single step process at 37oC in pH 5. The enzymatic hydrolysis of DGGS pretreated solids took place mostly during lag phase of L. coryniformis fermentation, with only a small amount of glucose consumed during the first 6 h. When exponential phase was started, glucose generation reduced as the microorganism started to consume glucose for D-lactic acid production. Higher concentrations of D-lactic acid were produced when SSF approach was applied, with 28 g/l D-lactic acid after 24 h of fermentation (84.5% yield). In contrast, 21.2 g/l D-lactic acid were produced when SHF was used. The optical pu rity of D-lactic acid produced from both experiments was 99.9%. Besides, approximately 2 g/l acetic acid was also generated due to lactic acid degradation after glucose depletion in SHF. SSF was proved an efficient towards DDGS ulilisation and D-lactic acid production, by reducing the overall processing time, yielding sufficient D-lactic acid concentrations without the generation of fermentation by-products.

Keywords: DDGS, alkaline pretreatment, SSF, D-lactic acid

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Authors: J. Y. Tan, L. C. Lum, M. G. Lee, S. Mansouri, K. Hapgood, X. D. Chen, M. W. Woo

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Folic acid (FA) is known to be an important supplement to prevent neural tube defect (NTD) in pregnant women. Similar to some commercial formulations, sodium bicarbonate solution is used as a solvent for FA. This work uses the antisolvent vapor precipitation (AVP), incorporating ethanol vapor as the convective drying medium in place of air to produce branch-like micro-structure FA particles. Interestingly, the dissolution rate of the resultant particle is 2-3 times better than the particle produce from conventional air drying due to the higher surface area of particles produced. The higher dissolution rate could possibly improve the delivery and absorption of FA in human body. This application could potentially be extended to other commercial products, particularly in less soluble drugs to improve its solubility.

Keywords: absorption, antisolvent vapor precipitation, dissolution rate, folic acid

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Authors: Sabriye Piskin, Sibel Kasap, Muge Sari Yilmaz

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Nanocrystalline TiO₂ particles were successfully synthesized via sol-gel and sonochemical combination using titanium tetraisopropoxide as a precursor at lower temperature for a short time. The effect of the reaction parameters (hydrolysis media, acid media, and reaction temperatures) on the synthesis of TiO₂ particles were investigated in the present study. Characterizations of synthesized samples were prepared by X-ray diffraction (XRD) analysis. It was shown that the reaction parameters played a significant role in the synthesis of TiO₂ particles.

Keywords: crystalline TiO2, sonochemical mechanism, sol-gel reaction, XRD

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Authors: Somya Ranjan Patro, Abhigna Bhatt, Arnab Banerjee

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Inertial amplifier has recently gained increasing attention as a new mechanism for vibration control of structures. Currently, theoretical investigations are undertaken by researchers to reveal its fundamentals and to understand its underline principles in altering the structural response of structures against dynamic loadings. This paper investigates experimental and analytical studies on the dynamic characteristics of hybrid beam inertial amplifier (HBIA). The analytical formulation of the HBIA has been derived by implementing the spectral element method and rigid body dynamics. This formulation gives the relation between dynamic force and the response of the structure in the frequency domain. Further, for validation of the proposed HBIA, the experiments have been performed. The experimental setup consists of a 3D printed HBIA of polylactic acid (PLA) material screwed at the base plate of the shaker system. Two numbers of accelerometers are used to study the response, one at the base plate of the shaker second one placed at the top of the inertial amplifier. A force transducer is also placed in between the base plate and the inertial amplifier to calculate the total amount of load transferred from the base plate to the inertial amplifier. The obtained time domain response from the accelerometers have been converted into the frequency domain using the Fast Fourier Transform (FFT) algorithm. The experimental transmittance values are successfully validated with the analytical results, providing us essential confidence in our proposed methodology.

Keywords: inertial amplifier, fast fourier transform, natural frequencies, polylactic acid, transmittance, vibration absorbers

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Authors: Aliakbar Sayadi, Thomas R. Neitzert, G. Charles Clifton, Min Cheol Han

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The present study aims to assess the performance of vermiculite concrete containing poly-lactic acid beads as an eco-friendly aggregate. Vermiculite aggregate was replaced by poly-lactic acid in percentages of 0%, 20%, 40%, 60% and 80%. Mechanical and thermal properties of concrete were investigated. Test results indicated that the inclusion of poly-lactic acid decreased the PH value of concrete and all the poly-lactic acid particles were dissolved due to the formation of sodium lactide and lactide oligomers when subjected to the high alkaline environment of concrete. In addition, an increase in thermal conductivity value of concrete was observed as the ratio of poly-lactic acid increased. Moreover, a set of equations was proposed to estimate the water-cement ratio, cement content and water absorption ratio of concrete.

Keywords: poly-lactic acid (PLA), vermiculite concrete, eco-friendly, mechanical properties

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Authors: Mohammed S. Razali, Kamel Khimeche, Dahah Hichem, Ammar Boudjellal, Djamel E. Kaderi, Nourddine Ramdani

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The use of additive manufacturing technologies has revolutionized various aspects of our daily lives. In particular, 3D printing has greatly advanced biomedical applications. While fused filament fabrication (FFF) technologies have made it easy to produce or prototype various medical devices, it is crucial to minimize the risk of contamination. New materials with antibacterial properties, such as those containing compounded silver nanoparticles, have emerged on the market. In a previous study, we prepared a newly sintered seashell filler (SSh) from bio-based seashells found along the Mediterranean coast using a suitable heat treatment process. We then prepared a series of polylactic acid (PLA) and polybutylene succinate (PBS) biocomposites filled with these SSh particles using a melt mixing technique with a twin-screw extruder to use them as feedstock filaments for 3D printing. The study consisted of two parts: evaluating the antibacterial activity of newly prepared biocomposites made of PLA and PBS reinforced with a sintered seashell in the first part and experimental and modeling analysis of the non-isothermal crystallization kinetics of these biocomposites in the second part. In the first part, the bactericidal activity of the biocomposites against three different bacteria, including Gram-negative bacteria such as (E. coli and Pseudomonas aeruginosa), as well as Gram-positive bacteria such as (Staphylococcus aureus), was examined. The PLA-based biocomposite containing 20 wt.% of SSh particles exhibited an inhibition zone with radial diameters of 8mm and 6mm against E. coli and Pseudo. Au, respectively, while no bacterial activity was observed against Staphylococcus aureus. In the second part, the focus was on investigating the effect of the sintered seashell filler particles on the non-isothermal crystallization kinetics of PLA and PBS 3D-printing composite materials. The objective was to understand the impact of the filler particles on the crystallization mechanism of both PLA and PBS during the cooling process of a melt-extruded filament in (FFF) to manage the dimensional accuracy and mechanical properties of the final printed part. We conducted a non-isothermal melt crystallization kinetic study of a series of PLA-SS and PBS-SS composites using differential scanning calorimetry at various cooling rates. We analyzed the obtained kinetic data using different crystallization kinetic models such as modified Avrami, Ozawa, and Mo's methods. Dynamic mode describes the relative crystallinity as a function of temperature; it found that time half crystallinity (t1/2) of neat PLA decreased from 17 min to 7.3 min for PLA+5 SSh and the (t1/2) of virgin PBS was reduced from 3.5 min to 2.8 min for the composite containing 5wt.% of SSh. We found that the coated SS particles with stearic acid acted as nucleating agents and had a nucleation activity, as observed through polarized optical microscopy. Moreover, we evaluated the effective energy barrier of the non-isothermal crystallization process using the Iso conversional methods of Flynn-Wall-Ozawa (F-W-O) and Kissinger-Akahira-Sunose (K-A-S). The study provides significant insights into the crystallization behavior of PLA and PBS biocomposites.

Keywords: avrami model, bio-based reinforcement, dsc, gram-negative bacteria, gram-positive bacteria, isoconversional methods, non-isothermal crystallization kinetics, poly(butylene succinate), poly(lactic acid), antbactirial activity

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Authors: Rangrong Yoksan, Amporn Sane, Nattaporn Khanoonkon, Chanakorn Yokesahachart, Narumol Noivoil, Khanh Minh Dang

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Polylactic acid (PLA) is the most commercially available bio-based and biodegradable plastic at present. PLA has been used in plastic related industries including single-used containers, disposable and environmentally friendly packaging owing to its renewability, compostability, biodegradability, and safety. Although PLA demonstrates reasonably good optical, physical, mechanical, and barrier properties comparable to the existing petroleum-based plastics, its brittleness and mold shrinkage as well as its price are the points to be concerned for the production of rigid and semi-rigid packaging. Blending PLA with other bio-based polymers including thermoplastic starch (TPS) is an alternative not only to achieve a complete bio-based plastic, but also to reduce the brittleness, shrinkage during molding and production cost of the PLA-based products. TPS is a material produced mainly from starch which is cheap, renewable, biodegradable, compostable, and non-toxic. It is commonly prepared by a plasticization of starch under applying heat and shear force. Although glycerol has been reported as one of the most plasticizers used for preparing TPS, its migration caused the surface stickiness of the TPS products. In some cases, mixed plasticizers or natural fibers have been applied to impede the retrogradation of starch or reduce the migration of glycerol. The introduction of fibers into TPS-based materials could reinforce the polymer matrix as well. Therefore, the objective of the present research is to study the effect of starch type (i.e. native starch and phosphate starch), plasticizer type (i.e. glycerol and xylitol with a weight ratio of glycerol to xylitol of 100:0, 75:25, 50:50, 25:75, and 0:100), and fiber content (i.e. in the range of 1-25 % wt) on properties of PLA/TPS blend and composite. PLA/TPS blends and composites were prepared using a twin-screw extruder and then converted into dumbbell-shaped specimens using an injection molding machine. The PLA/TPS blends prepared by using phosphate starch showed higher tensile strength and stiffness than the blends prepared by using the native one. In contrast, the blends from native starch exhibited higher extensibility and heat distortion temperature (HDT) than those from the modified starch. Increasing xylitol content resulted in enhanced tensile strength, stiffness, and water resistance, but decreased extensibility and HDT of the PLA/TPS blend. Tensile properties and hydrophobicity of the blend could be improved by incorporating silane treated-jute fibers.

Keywords: polylactic acid, thermoplastic starch, Jute fiber, composite, blend

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Authors: Manel Hannachi, Mustapha Nechiche, Said Azem

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This study focuses on biodegradable materials made from Poly-lactic acid (PLA) and vegetal reinforcements. Three materials are developed from PLA, as a matrix, and : (i) olive kernels (OK); (ii) alfa (α) short fibers and (iii) OK+ α mixture, as reinforcements. After processing of PLA pellets and olive kernels in powder and alfa stems in short fibers, three mixtures, namely PLA-OK, PLA-α, and PLA-OK-α are prepared and homogenized in Turbula®. These mixtures are then compacted at 180°C under 10 MPa during 15 mn. Scanning Electron Microscopy (SEM) examinations show that PLA matrix adheres at surface of all reinforcements and the dispersion of these ones in matrix is good. X-ray diffraction (XRD) analyses highlight an increase of PLA inter-reticular distances, especially for the PLA-OK case. These results are explained by the dissociation of some molecules derived from reinforcements followed by diffusion of the released atoms in the structure of PLA. This is consistent with Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analysis results.

Keywords: alfa short fibers, biodegradable composite, olive kernels, poly-lactic acid

Procedia PDF Downloads 123

Authors: Januar Parlaungan Siregar, Davindra Brabu Mathivanan, Dandi Bachtiar, Mohd Ruzaimi Mat Rejab, Tezara Cionita

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Natural fibres play a significant role in mass industries such as automotive, construction and sports. Many researchers have found that the natural fibres are the best replacement for the synthetic fibres in terms of cost, safety, and degradability due to the shortage of landfill and ingestion of non biodegradable plastic by animals. This study mainly revolved around pineapple leaf fibre (PALF) which is available abundantly in tropical countries and with excellent mechanical properties. The composite formed in this study is highly biodegradable as both fibre and matrix are both derived from natural based products. The matrix which is polylactic acid (PLA) is made from corn starch which gives the upper hand as both material are renewable resources are easier to degrade by bacteria or enzyme. The PALF is treated with different alkaline solution to remove excessive moisture in the fibre to provide better interfacial bonding with PLA. Thereafter the PALF is washed with distilled water several times before placing in vacuum oven at 80°C for 48 hours. The dried PALF later were mixed with PLA using extrusion method using fibre in percentage of 30 by weight. The temperature for all zone were maintained at 160°C with the screw speed of 50 rpm for better bonding and afterwards the products of the mixture were pelletized using pelletizer. The pellets were placed in the specimen-sized mould for hot compression under the temperature of 170°C at 5 MPa for 5 min and subsequently were cold pressed under room temperature at 5 MPa for 5 min. The specimen were tested for tensile and flexure strength according to American Society for Testing and Materials (ASTM) D638 and D790 respectively. The effect of surface modification on PALF with different alkali solution will be investigated and compared.

Keywords: natural fibre, PALF, PLA, composite

Procedia PDF Downloads 264

Authors: Natalia Fijol, Aji P. Mathew

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We present the processing and characterisation of three-dimensional (3D) monolith filters based on polylactic acid (PLA) reinforced with various nature-derived nanospecies such as hydroxyapatite, modified cellulose fibers and chitin fibers. The nanospecies of choice were dispersed in PLA through Thermally Induced Phase Separation (TIPS) method. The biocomposites were developed via solvent-assisted blending and the obtained pellets were further single-screw extruded into 3D-printing filaments and processed into various geometries using Fused Deposition Modelling (FDM) technique. The printed prototypes included cubic, cylindrical and hour-glass shapes with diverse patterns of printing infill as well as varying pore structure including uniform and multiple level gradual pore structure. The pores and channel structure as well as overall shape of the prototypes were designed in attempt to optimize the flux and maximize the adsorption-active time. FDM is a cost and energy-efficient method, which does not require expensive tools and elaborated post-processing maintenance. Therefore, FDM offers the possibility to produce customized, highly functional water purification filters with tuned porous structures suitable for removal of wide range of common water pollutants. Moreover, as 3D printing becomes more and more available worldwide, it allows producing portable filters at the place and time where they are most needed. The study demonstrates preparation route for the PLA-based, fully biobased composite and their processing via FDM technique into water purification filters, addressing water treatment challenges on an industrial scale.

Keywords: fused deposition modelling, water treatment, biomaterials, 3D printing, nanocellulose, nanochitin, polylactic acid

Procedia PDF Downloads 89

Authors: Somya R. Patro, Arnab Banerjee, G. V. Ramana

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A flexural beam carrying elastically mounted concentrated masses, such as engines, motors, oscillators, or vibration absorbers, is often encountered in mechanical, civil, and aeronautical engineering domains. To prevent resonance conditions, the designers must predict the natural frequencies of such a constrained beam system. This paper investigates experimental and analytical studies on vibration suppression in a cantilever beam with a tip mass with the help of spring-mass to achieve local resonance conditions. The system consists of a 3D printed polylactic acid (PLA) beam screwed at the base plate of the shaker system. The top of the free end is connected by an accelerometer which also acts as a tip mass. A spring and a mass are attached at the bottom to replicate the mechanism of the spring-mass resonator. The Fast Fourier Transform (FFT) algorithm converts time acceleration plots into frequency amplitude plots from which transmittance is calculated as a function of the excitation frequency. The mathematical formulation is based on the transfer matrix method, and the governing differential equations are based on Euler Bernoulli's beam theory. The experimental results are successfully validated with the analytical results, providing us essential confidence in our proposed methodology. The beam spring-mass system is then converted to an equivalent two-degree of freedom system, from which frequency response function is obtained. The H2 optimization technique is also used to obtain the closed-form expression of optimum spring stiffness, which shows the influence of spring stiffness on the system's natural frequency and vibration response.

Keywords: euler bernoulli beam theory, fast fourier transform, natural frequencies, polylactic acid, transmittance, vibration absorbers

Procedia PDF Downloads 72

Authors: Gómez S. Jennifer, Méndez V. Camila, Moncayo M. Diana, Vega M. Lizeth

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The cape gooseberry is a climacteric fruit; Colombia is one of the principal exporters in the world. The environmental condition of temperature and relative moisture decreases the titratable acidity and pH. These conditions and fruit maturation result in the fungal proliferation of Botrytis cinerea disease. Plastic packaging for fresh cape gooseberries was used for mechanical damage protection but created a suitable atmosphere for fungal growth. Beta-cyclodextrins are currently implemented as coatings for the encapsulation of hydrophobic compounds, for example, with bioactive compounds from essential oils such as cinnamaldehyde, which has a high antimicrobial capacity. However, it is a volatile substance. In this article, the casting method was used to obtain a polylactic acid (PLA) polymer film containing the beta-cyclodextrin-cinnamaldehyde inclusion complex, generating an insert that allowed the controlled release of the antifungal substance in packed cape gooseberries to decrease contamination by Botrytis cinerea in a latent state during storage. For the encapsulation technique, three ratios for the cinnamaldehyde: beta-cyclodextrin inclusion complex were proposed: (25:75), (40:60), and (50:50). Spectrophotometry, colorimetry in L*a*b* coordinate space and scanning electron microscopy (SEM) were made for the complex characterization. Subsequently, two ratios of tween and water (40:60) and (50:50) were used to obtain the polylactic acid (PLA) film. To determine mechanical and physical parameters of colourimetry in L*a*b* coordinate space, atomic force microscopy and stereoscopy were done to determine the transparency and flexibility of the film; for both cases, Statgraphics software was used to determine the best ratio in each of the proposed phases, where for encapsulation it was (50:50) with an encapsulation efficiency of 65,92%, and for casting the ratio (40:60) obtained greater transparency and flexibility that permitted its incorporation into the polymeric packaging. A liberation assay was also developed under ambient temperature conditions to evaluate the concentration of cinnamaldehyde inside the packaging through gas chromatography for three weeks. It was found that the insert had a controlled release. Nevertheless, a higher cinnamaldehyde concentration is needed to obtain the minimum inhibitory concentration for the fungus Botrytis cinerea (0.2g/L). The homogeneity of the cinnamaldehyde gas phase inside the packaging can be improved by considering other insert configurations. This development aims to impact emerging food preservation technologies with the controlled release of antifungals to reduce the affectation of the physico-chemical and sensory properties of the fruit as a result of contamination by microorganisms in the postharvest stage.

Keywords: antifungal, casting, encapsulation, postharvest

Procedia PDF Downloads 41