Structure and properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(L-lactic acid) quasi core/sheath melt-electrospun microfibers

2018 ◽  
Vol 89 (9) ◽  
pp. 1770-1781 ◽  
Author(s):  
Huaizhong Xu ◽  
Benedict Bauer ◽  
Masaki Yamamoto ◽  
Hideki Yamane
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Lactic Acid ◽  
Tensile Tests ◽  
Processing Parameters ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffraction Patterns

A facile route was proposed to fabricate core–sheath microfibers, and the relationships among processing parameters, crystalline structures and the mechanical properties were investigated. The compression molded poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/poly(L-lactic acid) (PLLA) strip enhanced the spinnability of PHBH and the mechanical properties of PLLA as well. The core–sheath ratio of the fibers was determined by the prefab strip, while the PLLA sheath component did not completely cover the PHBH core component due to the weak interfacial tension between the melts of PHBH and PLLA. A rotational target was applied to collect aligned fibers, which were further drawn in a water bath. The tensile strength and the modulus of as-spun and drawn fibers increased with increasing the take-up velocities. When the take-up velocity was above 500 m/min, the jet became unstable and started to break up at the tip of the Taylor cone, decreasing the mechanical properties of the fibers. The drawing process facilitated the crystallization of PLLA and PHBH, and the tensile strength and the modulus increased linearly with the increasing the draw ratio. The crystal information displayed from wide-angle X-ray diffraction patterns and differential scanning calorimetry heating curves supported the results of the tensile tests.

scholarly journals Relationship between the Stereocomplex Crystallization Behavior and Mechanical Properties of PLLA/PDLA Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1851
Author(s):  
Hye-Seon Park ◽  
Chang-Kook Hong
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Crystallization Behavior ◽  
Mechanical Analysis ◽  
X Ray Diffraction ◽  
Nucleation Agent ◽  
Scanning Calorimetry ◽  
Nucleation Sites ◽  
Wide Range ◽  
Degree Of Crystallization

Poly (l-lactic acid) (PLLA) is a promising biomedical polymer material with a wide range of applications. The diverse enantiomeric forms of PLLA provide great opportunities for thermal and mechanical enhancement through stereocomplex formation. The addition of poly (d-lactic acid) (PDLA) as a nucleation agent and the formation of stereocomplex crystallization (SC) have been proven to be an effective method to improve the crystallization and mechanical properties of the PLLA. In this study, PLLA was blended with different amounts of PDLA through a melt blending process and their properties were calculated. The effect of the PDLA on the crystallization behavior, thermal, and mechanical properties of PLLA were investigated systematically by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized optical microscopy (POM), dynamic mechanical analysis (DMA), and tensile test. Based on our findings, SC formed easily when PDLA content was increased, and acts as nucleation sites. Both SC and homo crystals (HC) were observed in the PLLA/PDLA blends. As the content of PDLA increased, the degree of crystallization increased, and the mechanical strength also increased.

scholarly journals Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Sintered Density ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Velocity Compaction ◽  
Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

Physical and Mechanical Properties of Cement Paste Were Used Partially with Fly Ash and Kaolin Waste

2017 ◽  
Vol 866 ◽  
pp. 199-203
Author(s):  
Chidchanok Chainej ◽  
Suparut Narksitipan ◽  
Nittaya Jaitanong
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Room Temperature ◽  
Physical And Mechanical Properties ◽  
Partial Replacement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lime Water ◽  
Diffraction Patterns ◽  
Iron Mold

The aims of this research were study the microstructures and mechanical properties for partial replacement of cement with Fly ash (FA) and kaolin waste (KW). Ordinary Portland cement were partially replaced with FA and KW in the range of 25-35% and 10-25% by weight of cement powder. The kaolin waste was ground for 180 minutes before using. The specimen was packing into an iron mold which sample size of 5×5×5 cm3. Then, the specimens were kept at room temperature for 24 hours and were moist cured in the incubation lime water bath at age of 3 days. After that the specimens were dry cured with plastic wrap at age of 3, 7, 14 and 28 days. After that the compounds were examined by x-ray diffraction patterns (XRD) and the microstructures were examined by scanning electron microscopy (SEM). The compressive strength was then investigated.

Research on compatibility and surface of high impact bio-based polyamide

2021 ◽  
pp. 095400832110055
Author(s):  
Yang Wang ◽  
Yuhui Zhang ◽  
Yuhan Xu ◽  
Xiucai Liu ◽  
Weihong Guo
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Crystallization Behavior ◽  
High Impact ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Scanning Electron

The super-tough bio-based nylon was prepared by melt extrusion. In order to improve the compatibility between bio-based nylon and elastomer, the elastomer POE was grafted with maleic anhydride. Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA) were used to study the compatibility and micro-distribution between super-tough bio-based nylon and toughened elastomers. The results of mechanical strength experiments show that the 20% content of POE-g-MAH has the best toughening effect. After toughening, the toughness of the super-tough nylon was significantly improved. The notched impact strength was 88 kJ/m2 increasing by 1700%, which was in line with the industrial super-tough nylon. X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) were used to study the crystallization behavior of bio-based PA56, and the effect of bio-based PA56 with high crystallinity on mechanical properties was analyzed from the microstructure.

Effect of Nitrogen Addition on Mechanical Property of Ti-Cr-Sn Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2126-2129 ◽  
Author(s):  
Yuichi Nakahira ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki ◽  
Hideki Hosoda
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Nitrogen Addition ◽  
N Addition ◽  
X Ray Diffraction ◽  
Solution Hardening ◽  
X Ray ◽  
Bcc Phase ◽  
Cold Workability

Effect of nitrogen (N) addition on mechanical properties of Ti-Cr-Sn alloy was investigated in this study. Ti-7mol%Cr-3mol%Sn was selected and less than 0.5wt% of N were systematically added. The alloys were characterized by optical microscopy, X-ray diffraction analysis and tensile tests at room temperature. The apparent phase was β (bcc) phase, whereas the presence of precipitates was confirmed in 0.5wt%N-added alloy only which did not exhibit sufficient cold workability. The grain size was not largely affected by N addition being less than 0.5wt%. Tensile tests revealed that less than 0.5wt%N addition improves the strength which is due to the solution hardening by interstitial N atoms.

The Structure and Mechanical Properties of Plastically Consolidated Al-Ni Alloy

2016 ◽  
Vol 682 ◽  
pp. 245-251 ◽  
Author(s):  
Grzegorz Włoch ◽  
Tomasz Skrzekut ◽  
Jakub Sobota ◽  
Antoni Woźnicki ◽  
Justyna Cisoń
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Intermetallic Phases ◽  
Scanning Calorimetry ◽  
Porosity Formation ◽  
X Ray ◽  
Ni Alloy ◽  
Thermal Stability Of

Mixed and preliminarily consolidated powders of aluminium and nickel (90 mass % Al and 10 mass % Ni) were hot extruded. As results the rod, 8 mm in diameter, was obtained. As-extruded material was subjected to the microstructural investigations using scanning electron microscopy (SEM/EDS) and X-ray analysis (XRD). The differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA) were also performed. The mechanical properties of as extruded material were determined by the tensile test and Vickers hardness measurements. In order to evaluate the thermal stability of PM alloy, samples were annealed at the temperature of 475 and 550 °C. After annealing Vickers hardness measurements and tensile tests were carried out. The plastic consolidation of powders during extrusion was found to be very effective, because no pores or voids were observed in the examined material. The detailed microstructural investigations and XRD analyses did not reveal the presence of the intermetallic phases in the as-extruded material. During annealing, the Al3Ni intermetallic compound was formed as the result of chemical reaction between the alloy components. The hardness of the alloy after annealing at the temperature of 475°C was found to be comparable to the hardness in as-extruded state. Annealing of the material at the temperature of 550°C results in hardness decreasing by about 50%, as the consequence of porosity formation and Al3Ni cracking.

Effects of Cooling Rate and Sn Addition on the Microstructure of Ti-Nb-Sn Alloys

2011 ◽  
Vol 172-174 ◽  
pp. 190-195 ◽  
Author(s):  
Giorgia T. Aleixo ◽  
Eder S.N. Lopes ◽  
Rodrigo Contieri ◽  
Alessandra Cremasco ◽  
Conrado Ramos Moreira Afonso ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Melting Furnace ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Arc Melting ◽  
Ti Alloys ◽  
Ω Phase

Ti-based alloys present unique properties and hence, are employed in several industrial segments. Among Ti alloys, β type alloys form one of the most versatile classes of materials in relation to processing, microstructure and mechanical properties. It is well known that heat treatment of Ti alloys plays an important role in determining their microstructure and mechanical behavior. The aim of this work is to analyze microstructure and phases formed during cooling of β Ti-Nb-Sn alloy through different cooling rates. Initially, samples of Ti-Nb-Sn system were prepared through arc melting furnace. After, they were subjected to continuous cooling experiments to evaluate conditions for obtaining metastable phases. Microstructure analysis, differential scanning calorimetry and X-ray diffraction were performed in order to evaluate phase transformations. Depending on the cooling rate and composition, α” martensite, ω phase and β phase were obtained. Elastic modulus has been found to decrease as the amount of Sn was increased.

Contribution of the hybrid component to the structure and properties of ceramics based on metastable phases Al2O3

2021 ◽  
pp. 127-136
Author(s):  
A. V. Maletsky ◽  
T. E. Konstantinova ◽  
D. R. Belichko ◽  
G. K. Volkova ◽  
V. V. Burkhovetsky
Keyword(s):  
Mechanical Properties ◽  
Yttrium Aluminum Garnet ◽  
Metastable Phase ◽  
Physical And Mechanical Properties ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Mutual Inhibition ◽  
X Ray ◽  
Tetragonal Lattice ◽  
Yttrium Aluminum

The paper presents results of the study of the effect of doping with yttrium oxide on ceramics of the composition (γ + θ) Al2O3 + nY2O3 (n = 0, 1, 2, 3 wt%), sintered at 1550°C for 2 h, from powders of the specified composition annealed at temperatures of 500 , 800, 1000°С. X-ray diffraction analysis established the formation in ceramics of yttrium aluminum garnet Y3Al5O12 (YAG) and a metastable phase of the same composition with a tetragonal lattice type in powders at temperatures above 1200°C. The effect of YAG on the physical and mechanical properties was established: high properties were demonstrated by ceramics of the composition α-Al2O3 + 2wt% Y2O3, obtained from a powder annealed at 1000°C. In addition, high physical and mechanical properties were observed in ceramics of the composition α-Al2O3 + 0wt% Y2O3, obtained from a powder annealed at 800°C. The effect of the so-called “mutual protection against crystallization” was discovered, which consists in the mutual inhibition of crystallization processes in powders of the Al2O3 – Y2O3 system.

Effects of Extrusion on the Mechanical Properties and Damping Capacity of Mg-1.8Cu-0.5Mn Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 257-260 ◽  
Author(s):  
Zhen Yan Zhang ◽  
Li Ming Peng ◽  
Xiao Qin Zeng ◽  
Lin Du ◽  
Lan Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Damping Capacity ◽  
X Ray Diffraction ◽  
Dynamic Mechanical Analyzer ◽  
X Ray ◽  
Solute Atoms

Effects of extrusion on mechanical properties and damping capacity of Mg-1.8wt.%Cu -0.5wt.%Mn (MCM1805) alloy have been investigated. Tensile tests and dynamic mechanical analyzer were respectively used to measure tensile properties and damping capacity at room temperature of as-cast and as-extruded MCM1805 alloy. The microstructure was studied using optical microscope, X-ray diffraction and scanning electron microscope with an energy dispersive X-ray spectrometer. Granato-Lücke model was used to explain the influences of extrusion on damping capacity of MCM1805 alloy. The results showed that extrusion dramatically decreases the grain size but has little influence on phase composition and solute atoms concentration of MCM1805 alloy, and the grain refinement was the dominant reason for the obvious increase of tensile properties and decrease of internal friction of MCM1805 alloy.

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.

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