scholarly journals Morphology, Thermal and Mechanical Properties of Co-Continuous Porous Structure of PLA/PVA Blends by Phase Separation

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1083
Author(s):  
Natthapong Chuaponpat ◽  
Tsubasa Ueda ◽  
Akira Ishigami ◽  
Takashi Kurose ◽  
Hiroshi Ito
Keyword(s):  
Continuous Phase ◽  
Hot Water ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Poly Vinyl Alcohol ◽  
High Porosity ◽  
Absorption Energy ◽  
Maximum Indentation Depth ◽  
The Degree Of Crystallinity ◽  
Porous Morphology

Poly (lactic acid) (PLA) was blended with poly (vinyl alcohol) (PVA) in the composition of 70/30 (L7V3), 60/40 (L6V4), and 50/50 (L5V5) wt.%. L7V3 exhibits a sea–island morphology, while L6V4 and L5V5 show co-continuous phase morphologies. These polymers exhibited a solitary glass transition temperature, which obeyed the Fox equation. Thereafter, the blends were made porous by an etching process in hot water (35 °C) for 0–7 days, to remove PVA. The maximum etched PVA content of L7V3, L6V4, and L5V5 was 0.5%, 13.4%, and 36.1%, respectively; hence, L5V5 exhibited a co-continuous porous morphology with the porosity of 43.4%, the degree of swelling of 47.5%, and the pore size of 2 µm. The degree of crystallinity of PLA, exposed PLA, and L7V3 showed an insignificant change. L5V5, having the highest porosity, demonstrated the highest increase in the degree of crystallinity of approximately two times, because water induced the crystallization of PLA. The high porosity of L5V5 exhibited an excellent absorption property by increasing absorption energy more than two times, as obtained by micro indention. It had the maximum indentation depth more than 250 µm. Flexural and tensile properties considerably decreased with an increase in the porosity.

scholarly journals Hemp Fibre Reinforced Poly(Lactic Acid) Composites

2007 ◽  
Vol 29-30 ◽  
pp. 337-340 ◽  
Author(s):  
M.A. Sawpan ◽  
K.L. Pickering ◽  
Alan Fernyhough
Keyword(s):  
Lactic Acid ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Hemp Fibre ◽  
Reinforcing Material ◽  
Fibre Loading ◽  
The Degree Of Crystallinity

The potential of hemp fibre as a reinforcing material for Poly(lactic acid) (PLA) was investigated. Good interaction between hemp fibre and PLA resulted in increases of 100% for Young’s modulus and 30% for tensile strength of composites containing 30 wt% fibre. Different predictive ‘rule of mixtures’ models (e.g. Parallel, Series and Hirsch) were assessed regarding the dependence of tensile properties on fibre loading. Limited agreement with models was observed. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) studies showed that hemp fibre increased the degree of crystallinity in PLA composites.

Influence of selective laser sintering process parameters on microstructure and physicochemical properties of poly(vinyl alcohol) for the production of scaffolds

2020 ◽  
Vol 26 (6) ◽  
pp. 1155-1164
Author(s):  
Camila Fernandes Higa ◽  
Thatyanne Gradowski ◽  
Selene Elifio-Esposito ◽  
Marcelo Fernandes de Oliveira ◽  
Paulo Inforçatti ◽  
...  
Keyword(s):  
Cell Culture ◽  
Process Parameters ◽  
Vinyl Alcohol ◽  
Laser Power ◽  
Selective Laser Sintering ◽  
Degree Of Crystallinity ◽  
Poly Vinyl Alcohol ◽  
Content Type ◽  
The Degree Of Crystallinity

Purpose This study aims to investigate the production of scaffolds by selective laser sintering (SLS) using poly(vinyl alcohol) (PVA) polymer, for in vitro studies, a relatively new and growing area in which scaffolds could be used in the design of three-dimensional models for in vitro disease model or tissue equivalent for safety and effectiveness tests. Design/methodology/approach The influence of the SLS process parameters laser power, 26 W and 32 W, and number of laser scans, 1, 2, 4 and 6, on the surface microstructure of the samples and on the degree of crystallinity and chemical stability of PVA material, was investigated using powder with particle size of 20-320 µm. Laser sintered PVA samples were subjected to cell culture tests using osteoblastic cells derived from human osteosarcoma (SaOs-2). Findings The laser power has no significant influence on the microstructure of the laser-sintered samples, however the number of scans has a considerable influence on the sintering degree; the SLS process causes a decrease in the degree of crystallinity and changes the chemical structure of the as-received PVA, especially when using higher laser power and more number of scans. Preliminary in vitro cell culture tests show that the laser-sintered PVA material is biocompatible with SaOs-2 cells. Originality/value SLS offers good potential for the fabrication of scaffolds and thus, may be applied as an alternative to conventional scaffold fabrication processes to overcome their limitations.

scholarly journals Poly(lactic acid)/Cellulose Films Produced from Composite Spheres Prepared by Emulsion-Solvent Evaporation Method

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 66 ◽  
Author(s):  
Sónia Sousa ◽  
Ana Costa ◽  
Abílio Silva ◽  
Rogério Simões
Keyword(s):  
Lactic Acid ◽  
Surface Chemistry ◽  
Solvent Evaporation ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Poly Vinyl Alcohol ◽  
Cellulose Films ◽  
Chemically Modified ◽  
Biocomposite Films ◽  
Biocomposite Film

The compound of poly(lactic acid) (PLA) and cellulose was made by the emulsion-solvent evaporation technique in order to obtain spheres which are then compression molded to produce a biocomposite film. The effect of the dispersant (poly(vinyl alcohol)—PVA)/PLA ratio on the spheres yield was studied. Moreover, to evaluate the effect of cellulose particle size and surface chemistry on the process yield, unbleached eucalypt kraft pulp and microcrystalline cellulose (MCC), both unmodified and physically or chemically modified were used. PLA/cellulose spheres were characterized regarding its physical properties. It was found that the spheres yield is essentially determined by the PVA/PLA ratio and the percentage of cellulose incorporation is greatly affected by the surface chemistry of cellulose. Regarding the films, DSC runs showed a significant effect of the cellulose type incorporated into PLA matrix on the cold crystallization temperature and on the degree of crystallinity of the biocomposite films. The measurement of tensile properties of the biocomposite films revealed that the strength, elongation at break and toughness (tensile energy absorption at break) of the films incorporating unmodified and chemically modified MCC were substantially improved.

scholarly journals From disposal to sustainable development: technological potential of poly(lactic acid) (PLA) blends with 3D filament waste

2020 ◽  
Vol 9 (12) ◽  
pp. e13291210767
Author(s):  
Wellerson Salomão Diniz Marinho ◽  
Carlos Bruno Barreto Luna ◽  
Edcleide Maria Araújo ◽  
Carlos Heitor de Andrade Lustosa ◽  
Celso Rosendo Bezerra Filho ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Softening Temperature ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Continuous Growth ◽  
Technological Potential ◽  
Twin Screw ◽  
Injection Molded ◽  
The Degree Of Crystallinity

Additive manufacturing is growing rapidly in the automotive, medical, and aerospace industries as an option for the manufacturing of products. However, there is a continuous growth in the amount of waste generated by 3D filaments, thus, the reuse practice becomes important, since it brings environmental and economic gains. The present research evaluated the mechanical, thermal, thermomechanical and rheological properties of PLA/PLAr blends containing post-consumption 3D filament. The blends were prepared in a co-rotational twin screw extruder and, subsequently, the extruded granules were injection molded. As the PLAr content in the blends (PLA/PLAr) increased, there was a reduction in viscosity, indicating an improvement in manufacturability. The PLA/PLAr blend (75/25 % wt.) increased the degree of crystallinity compared to neat PLA, indicating that PLAr acted as a nucleating agent. As a consequence, the PLA/PLAr blend (75/25 % wt.) showed performance comparable to neat PLA in thermal stability, elastic modulus, tensile strength, Shore D hardness, impact strength, heat deflection temperature (HDT) and Vicat softening temperature. The reuse of post-consumption 3D filament PLA is feasible for the development of materials with good properties. In addition, value is added to the post-consumption material and there is a contribution to sustainable development.

Blending and plasticising effects on the behaviour of poly(lactic acid)/poly(ε-caprolactone)

2018 ◽  
Vol 26 (5-6) ◽  
pp. 337-345 ◽  
Author(s):  
Nesrine Khitas ◽  
Kamira Aouachria ◽  
Mohamed Tahar Benaniba
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Triethyl Citrate ◽  
Acetyl Tributyl Citrate ◽  
The Degree Of Crystallinity

Polymer blending is one of the most convenient methods to be used to overcome the limitations of some single properties of polymers and to achieve the combinations required for specific applications. Another feasible common practice is the incorporation of additives of low molecular weight such as plasticisers to impart flexibility, improve toughness and lower the glass transition temperature ( Tg). This study focused on the effects of blending and plasticising on the crystallisation behaviour of poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL). PCL with longer degradation time compared with other polymers was blended with PLA to overcome the limitation of its brittleness and poor thermal stability. Acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (TEC) were used as plasticiser in PLA/PCL blends. The rigid and plasticised blends at various ratios were analysed by differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The results revealed a slight increase in the degree of crystallinity and a significant increase in the Tg of PLA due to the addition of PCL. The addition of ATBC has promoted a decrease in thermal stability of the blends. The slight increase in the degree of crystallinity suggested that PCL acted as a nucleating agent. The citrate plasticisers were shown to lower the Tg and have much more enhanced the crystallisation of PLA. Moreover, the rigid and plasticised blends were shown to be partially miscible.

Studies on thermal and degradation kinetics of cellulose micro/nanoparticle filled polylactic acid (PLA) based nanocomposites

2021 ◽  
pp. 096739112098717
Author(s):  
Achal Bhiogade ◽  
Murugasamy Kannan
Keyword(s):  
Degradation Kinetics ◽  
Thermo Gravimetric Analysis ◽  
Composite Films ◽  
Degree Of Crystallinity ◽  
Hydroxyl Group ◽  
Poly Lactic Acid ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Kinetics Of ◽  
The Degree Of Crystallinity

The aim of this work is to understand the effect of concentration of plasticizer, particle size and wt% of nanoparticles on nanocomposites by fabricating poly lactic acid (PLA) based bio-nanocomposites. The bio-nanocomposites were prepared by a solution casting method with PLA as the matrix, chloroform as solvent and poly ethylene glycol (PEG) as plasticizer. Microcrystalline cellulose (MCC) and cellulose nanocrystal (CNC) were used as reinforcements in 1, 3 and 5 wt% to modify the properties of the bio-nanocomposite. The degradation kinetics of the PLA based composites were determined by using the Coats-Redfern equation over the range of 0-5 wt% of MCC and CNC. Fabricated PLA based composite films were analyzed by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM). The analyses showed that the amount of PEG, MCC and CNC affected the degree of crystallinity. DSC results showed that the MCC/CNC content level affected the degree of crystallinity compared to neat PLA. The FTIR showed a free hydroxyl group (−OH) present in the system. The TGA analysis showed that the PLA/MCC3%/ PEG 10% composition had the highest stability compared to the other compositions but less than neat PLA.

scholarly journals Characteristics of sago pith and sago bark waste from Seram Island, Maluku, Indonesia

2019 ◽  
Vol 20 (12) ◽  
Author(s):  
Herman Siruru ◽  
WASRIN SYAFII ◽  
I NYOMAN J. WISTARA ◽  
GUSTAN PARI
Keyword(s):  
Lignin Content ◽  
Small Diameter ◽  
Volatile Matter ◽  
Water Soluble ◽  
Hot Water ◽  
Degree Of Crystallinity ◽  
Main Peak ◽  
Phenol Compound ◽  
Sago Bark ◽  
The Degree Of Crystallinity

Abstract. Siruru H, Syafii W, Wistara I. N. J, Pari G. 2019. Characteristics of Metroxylon rumphii (pith and bark waste) from Seram Island, Maluku, Indonesia. Biodiversitas 20: 3517-3526. Sago (Metroxylon rumphii Martius) pith waste (SPW) and sago bark waste (SBW) are lignocellulosic materials that can be used for various needs directly or indirectly. It is necessary to understand SPW and SBW characteristics to maximize their utilization. In this study, we analyzed the proximate, ultimate, and crystallinity by XRD, the functional groups by FTIR, morphology by SEM, and the derivate analysis of hot water-soluble extractives by GCMS. The contents of SPW and SBW hot-water soluble extractive, lignin, and holocellulose were 57.7 and 4.9%, 6.1 and 29.4%, and 45.74 and 66.74%, respectively. The volatile matter, ash content, silica, fixed carbon, C, H, and O contents of the SPW and SBW were 81.48 and 84.56%, 1.30 and 3.04%, 1.25% and 2.03, 12.77 and 18.06%, 37.93 and 44.64%, 6.37 and 6.49%, and 47.75 and 51.10%, respectively. The degree of crystallinity of SPW was 15.04%, while that of SBW was 47.28%, where both have a monoclinic structure with the main peak by 2Ɵ 16° and 26°. SPW and SBW contained several minerals such as silica, boron, sulfur, and phosphorus. The surface morphology of the SPW was porous with a small diameter and thin cell wall, while that of SBW was covered by minerals. Nitrogen, alcohol, and sugar group compounds were found more in SPW, whereas phenol compound was more in SBW. SBW has high lignin content and SPW has a very large amount of hot water-soluble extractive.

scholarly journals Silicon and Phosphorus Linkage with Iron via Oxygen in the Amorphous Matrix of Gallionella ferruginea Stalks

2011 ◽  
Vol 78 (1) ◽  
pp. 236-241 ◽  
Author(s):  
Tomoko Suzuki ◽  
Hideki Hashimoto ◽  
Atsushi Itadani ◽  
Nobuyuki Matsumoto ◽  
Hitoshi Kunoh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Degree Of Crystallinity ◽  
High Porosity ◽  
Content Type ◽  
X Ray ◽  
Transmission Electron ◽  
Primary Particles ◽  
Constituent Elements ◽  
The Degree Of Crystallinity

ABSTRACTBacterial species belonging to the genusGallionellaare Fe-oxidizing bacteria that produce uniquely twisted extracellular stalks consisting of iron-oxide-encrusted inorganic/organic fibers in aquatic environments. This paper describes the degree of crystallinity ofGallionellastalks and the chemical linkages of constituent elements in the stalk fibers. Transmission electron microscopy revealed that the matrix of the fiber edge consisted of an assembly of primary particles of approximately 3 nm in diameter. Scanning transmission electron microscopy revealed the rough granular surfaces of the fibers, which reflect the disordered assembly of the primary particles, indicating a high porosity and large specific surface area of the fibers. This may provide the surface with broader reactive properties. X-ray diffractometry, selected-area electron diffraction, and high-resolution transmission electron microscopy together showed that the primary particles had an amorphous structure. Furthermore, energy-dispersive X-ray analysis and Fourier transform infrared spectroscopy detected the bands characteristic of the vibrational modes assigned to O-H, Fe-O-H, P-O-H, Si-O-H, Si-O-Fe, and P-O-Fe bonds in the stalks, suggesting that the minor constituent elements P and Si could affect the degree of crystallinity of the fibers by linking with Fe via O. This knowledge about the mutual associations of these elements provides deeper insights into the unique inorganic/organic hybrid structure of the stalks.

PVA/PVAm Hydrogel Membranes for Removal of Metal Ions from Aqueous Solution

2011 ◽  
Vol 130-134 ◽  
pp. 1507-1510 ◽  
Author(s):  
Qiang Chen ◽  
Lin Zhu
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Degree Of Crystallinity ◽  
Poly Vinyl Alcohol ◽  
Degree Of Ionization ◽  
Hydrogel Membranes ◽  
Swelling Studies ◽  
Removal Of Metal ◽  
Removal Of Metal Ions ◽  
The Degree Of Crystallinity

Glutaraldehyde cross-linked Poly (vinyl alcohol)/Polyvinylamine (PVA/PVAm) membranes for removal of metal ions from aqueous solution were prepared by solution casting and solvent evaporation techniques. The membranes were characterized using XRD, Swelling studies and metal ions adsorption experiments. The results show that PVA/PVAm membranes exhibit semi-crystalline natures as PVA macromolecular, however, the degree of crystallinity of membranes decrease as PVAm increased. The membranes were pH-sensitive and the swelling ability of membranes was significantly enhanced. It was found that the change of swelling behavior versus pH was consistent with the change of degree of ionization versus pH. The amount of Cu2+ions adsorbed increased as PVAm increased as well as increasing pH of solution in the range of 2.5~6.0.

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