A setup to characterize the tensile mechanical properties of poly(L-lactic acid) materials applied in bioresorbable polymer stents

2021 ◽  
Vol 16 (12) ◽  
pp. P12005
Author(s):  
G. Zhao ◽  
R. He ◽  
X. Li ◽  
J. Zhang ◽  
J. Cheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Yield Strength ◽  
Biodegradable Polymer ◽  
Elasticity Modulus ◽  
Breaking Elongation ◽  
Measurement Results ◽  
Different Shapes ◽  
Bioresorbable Polymer ◽  
Set Up

Abstract A method for testing mechanical properties of miniature poly(L-lactic acid)(PLLA) specimens is instrumented and set up in this research. This method is specially designed to measure mechanical properties, including elasticity modulus, yield strength and breaking elongation, of miniature PLLA specimens in three different shapes at various tensile speeds and temperatures. Moreover, the measurement results are significantly dependent on the tensile speeds and temperatures. This phenomenon further verifies the obvious existence of the viscoelasticity of PLLA. Finally, it can be concluded that, with this method, mechanical properties of PLLA can be better investigated and understood, especially for PLLA used for biodegradable polymer stents.

Preparation and Properties of High-Density Polyethylene/Silica Composites

2011 ◽  
Vol 279 ◽  
pp. 115-119 ◽  
Author(s):  
Jing Long Gao ◽  
Yan Hui Liu ◽  
Shou Dong Wei
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Thermal Degradation ◽  
Yield Strength ◽  
Silicon Dioxide ◽  
High Density Polyethylene ◽  
High Density ◽  
Breaking Elongation ◽  
Silica Dioxide ◽  
Silicon Dioxide Content

High-density polyethylene (HDPE)/silica composites with different silicon dioxide fraction were prepared by the melting blend method. The effects of silicon dioxide content on the thermal properties and mechanical properties were mainly investigated. The results show that the thermal degradation of the composites shifts towards higher temperatures as the concentration of silicon dioxide is increased. With increasing silica dioxide content, the tension yield strength of HDPE/silicon composites increased, but its breaking elongation decreased. When silicon dioxide content is 5 %, the tension yield strength and its breaking elongation are 29.33 MPa and 102.82 %, respectively.

STRUCTURAL FEATURES AND MECHANICAL PROPERTIES OF PLLA/PEARL POWDER SCAFFOLDS

2013 ◽  
Vol 13 (01) ◽  
pp. 1350020 ◽  
Author(s):  
Y. S. LIU ◽  
Q. L. HUANG ◽  
Q. L. FENG ◽  
N. M. HU ◽  
O. ALBERT
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Lactic Acid ◽  
Yield Strength ◽  
Porous Structure ◽  
Freeze Drying ◽  
Structural Features ◽  
Drying Method ◽  
Composite Scaffolds ◽  
Powder Content

In order to improve the mechanical properties of scaffolds for bone tissue engineering, the present study aims to bring calcium carbonate (CaCO3) with signaling molecules, namely pearl powder, into poly(L-lactic acid) (PLLA). PLLA/aragonite and PLLA/vaterite scaffolds were successfully fabricated by the freeze-drying method. Both composite scaffolds had a similar porous structure but a different saturated content of pearl powders. For both scaffolds, the porosity decreases and yield strength increases as pearl powder content increases. Introducing pearl powders into PLLA can improve the mechanical properties of the scaffolds. The porous structure plays a crucial role in the yield strength of pure PLLA scaffolds, whereas the yield strength of PLLA/pearl powder scaffolds mostly relies on pearl powder content.

scholarly journals Investigations on the mechanics and tribology of multilayer graphene nanosheet in TiAl aviation composites

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110407
Author(s):  
Zhao Dong ◽  
Kang Yang ◽  
Feizhi Zhang
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Elasticity Modulus ◽  
Graphene Nanosheets ◽  
Multilayer Graphene ◽  
Lubrication Film ◽  
Tribological Behaviors ◽  
Low Energy Consumption ◽  
Applied Forces ◽  
Material Volume

Requirements of low energy consumption and material-volume reduction in the aerospace industry have spurred improvements of mechanical and tribological behaviors of TiAl (TA) alloys. TA-graphene (TAG) has poorer mechanical properties (6.02 ± 0.42 GPa nano-hardness, 150 ± 12.32 GPa elasticity modulus, and 802 ± 21 MPa yield strength) than (6.25 ± 0.52 GPa nano-hardness, 159 ± 14.21 GPa elasticity modulus, and 850 ± 19 MPa yield strength) of TA-graphene-silver (TAGS). Multilayer graphene nanosheets were curled into small loops to resist the applied forces, and helped to improve the mechanical properties of the TAGS. Subsequently, the graphene nanosheets enhanced the tribological performances as observed by the ball-on-disk tribometer. The following factors were primarily responsible for more excellent tribological behaviors (approximately 0.27 friction coefficient, 2.82 × 10−4 mm3 N−1 m−1 wear rate) of TAGS than those of the TAG: intra-lamellar separation of graphene, graphene-enhanced capacity of wear scar, plastic deformation of silver, the excellent cooperation lubrication of graphene-silver, the low-hardness lubrication film on the grain-refined layer, the well-distributed film grain, and low grain orientation angles.

Preparation of Biodegradable Polymer Blended of Poly(L-Lactic Acid)/Cellulose Acetate Films in the Solvent Mixture

2013 ◽  
Vol 664 ◽  
pp. 702-706 ◽  
Author(s):  
C. Witthayaprapakorn ◽  
K. Thananukul ◽  
N. Suttenun ◽  
P. Punyamoonwongsa ◽  
Robert Molloy
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Green Chemistry ◽  
Cellulose Acetate ◽  
Biodegradable Polymer ◽  
Plastic Material ◽  
Solvent Mixture ◽  
Environmental Responsibility ◽  
Acid Condition ◽  
Blend Films

Nowadays, bio-plastic is the most popular in packaging field. Green chemistry and environmental responsibility has led it to develop the bio-plastic for use as packaging. Polylactic acid (PLA) is the well known staring material in this area. However, some properties of PLA films have to develop. Polymer blend is the interesting technique, in this work, PLA/Cellulose acetate (CA) blend films were prepare by casting solution at various compositions. Mixing solvent of Chloroform and acetone in acid condition were used, it was found that the mixing solvent can improved the compatibility and mechanical properties of the blend films. From this work CA can significantly increase PLA properties both the usefulness and the possible applications for bio-plastic material.

Study of Bismuth Telluride Crystal Strength

2019 ◽  
pp. 1-8
Author(s):  
A. A. Gorbatovskiy
Keyword(s):  
Tensile Strength ◽  
Bismuth Telluride ◽  
Elasticity Modulus ◽  
Testing Machine ◽  
Bend Testing ◽  
Instron Testing Machine ◽  
Measurement Results ◽  
Strength Tests ◽  
Semiconductor Properties

The article presents results of strength tests of bismuth telluride prismatic samples obtained by growing crystals. These crystals have semiconductor properties and are used in the heat machines, the run-ability of which largely depends on the strength of crystals. Data available in the literature are significantly different from each other. It has been shown that, the most consistent strength tests results are obtained in case of bend testing. The measurement results of the elasticity modulus and tensile strength are given. For tests, an INSTRON testing machine with maximum direct stress of the 1000 H was used.

Possibilities of using biodegradable polymeric materials in the agricultural sector

2020 ◽  
Vol 67 (2) ◽  
pp. 115-120
Author(s):  
Raisa A. Alekhina ◽  
Victoriya E. Slavkina ◽  
Yuliya A. Lopatina
Keyword(s):  
Mechanical Properties ◽  
Biodegradable Polymers ◽  
Biodegradable Polymer ◽  
Agricultural Sector ◽  
Polymeric Materials ◽  
Polymer Materials ◽  
Limiting Factors ◽  
Research Purpose ◽  
Biodegradable Materials ◽  
Advantages And Disadvantages

The article presents options for recycling polymers. The use of biodegradable materials is promising. This is a special class of polymers that can decompose under aerobic or anaerobic conditions under the action of microorganisms or enzymes forming natural products such as carbon dioxide, nitrogen, water, biomass, and inorganic salts. (Research purpose) The research purpose is in reviewing biodegradable materials that can be used for the manufacture of products used in agriculture. (Materials and methods) The study are based on open information sources containing information about biodegradable materials. Research methods are collecting, studying and comparative analysis of information. (Results and discussion) The article presents the advantages and disadvantages of biodegradable materials, mechanical properties of the main groups of biodegradable polymers. The article provides a summary list of agricultural products that can be made from biodegradable polymer materials. It was found that products from the general group are widely used in agriculture. Authors have found that products from a special group can only be made from biodegradable polymers with a controlled decomposition period in the soil, their use contributes to increasing the productivity of crops. (Conclusions) It was found that biodegradable polymer materials, along with environmental safety, have mechanical properties that allow them producing products that do not carry significant loads during operation. We have shown that the creation of responsible products (machine parts) from biodegradable polymers requires an increase in their strength properties, which is achievable by creating composites based on them. It was found that the technological complexity of their manufacture and high cost are the limiting factors for the widespread use of biodegradable polymers at this stage.

scholarly journals Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3732
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak ◽  
Tomasz Torzewicz ◽  
Marcin Janicki
Keyword(s):  
Optical Properties ◽  
Thermal Resistance ◽  
Optical Power ◽  
Junction Temperature ◽  
Operating Parameters ◽  
Cold Plate ◽  
Optical Efficiency ◽  
Forward Current ◽  
Measurement Results ◽  
Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

Conductivity and mechanical properties of carbon black-reinforced poly(lactic acid) (PLA/CB) composites

2021 ◽  
Author(s):  
Jipeng Guo ◽  
Chi-Hui Tsou ◽  
Yongqi Yu ◽  
Chin-San Wu ◽  
Xuemei Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Carbon Black ◽  
Poly Lactic Acid

scholarly journals A Review: Research Progress in Modification of Poly (Lactic Acid) by Lignin and Cellulose

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 776
Author(s):  
Sixiang Zhai ◽  
Qingying Liu ◽  
Yuelong Zhao ◽  
Hui Sun ◽  
Biao Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Composite Materials ◽  
Crystallization Rate ◽  
Research Progress ◽  
Poly Lactic Acid ◽  
Green Composite ◽  
Materials Development ◽  
Research Attention ◽  
Biomass Components

With the depletion of petroleum energy, the possibility of prices of petroleum-based materials increasing, and increased environmental awareness, biodegradable materials as a kind of green alternative have attracted more and more research attention. In this context, poly (lactic acid) has shown a unique combination of properties such as nontoxicity, biodegradability, biocompatibility, and good workability. However, examples of its known drawbacks include poor tensile strength, low elongation at break, poor thermal properties, and low crystallization rate. Lignocellulosic materials such as lignin and cellulose have excellent biodegradability and mechanical properties. Compounding such biomass components with poly (lactic acid) is expected to prepare green composite materials with improved properties of poly (lactic acid). This paper is aimed at summarizing the research progress of modification of poly (lactic acid) with lignin and cellulose made in in recent years, with emphasis on effects of lignin and cellulose on mechanical properties, thermal stability and crystallinity on poly (lactic acid) composite materials. Development of poly (lactic acid) composite materials in this respect is forecasted.

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