scholarly journals Synthesis of Diblocks Copolymers PCL-b-PLLA and Optimization of its Mechanical Characteristics

2010 ◽  
Vol 12 (2) ◽  
pp. 117
Author(s):  
Vitali T. Lipik ◽  
Leonardus K. Widjaja ◽  
Sing S. Liow ◽  
Subramanian S. Venkatraman ◽  
Marc J.M. Abadie
Keyword(s):  
Mechanical Properties ◽  
Polymeric Materials ◽  
Maximum Load ◽  
Absolute Maximum ◽  
Elongation At Break ◽  
Block Polymer ◽  
Second Stage ◽  
Molar Weight ◽  
Block Structures ◽  
To Receive

<p>Biodegradable polymeric materials have a wide application in medicine, ecology and a number of other branches of industry. Overwhelming majority of such polymers is well exposed to the biodegradation, but they have mechanical properties which don’t correspond to the requirements of application areas. As a rule, these materials possess low elasticity. In this work, optimization of mechanical properties of biodegradable polymers and the search of structure of block polymer on the basis of ε-caprolactone and L-lactide with the maximal elasticity are considered. The purpose of the work is to receive the diblock polymer with mechanical properties as close as possible to elastomer for medical devices. The task is reached due to application of design of experiment with the subsequent optimization of the received results. Maximization of elongation at maximum load of received polymer is solved by the greatest possible reduction of crystallinity with a variation of molar weight of both part of diblock: polycaprolactone and polylactide. The absolute maximum of elongation at maximum load of synthesized diblock polymers is found. It is established that diblock with the following structure possesses the best mechanical properties in this class of polymers. Molar weight of the polycaprolactone block is 5000 Da while polylactide block is 7000 Da. Elongation at maximum load of this polymer was about 30%. In the second stage of our research, we try to improve the mechanical properties by making one block partly random (PCL-co-PLLA). Second block was made from homopolymer (PLLA). Maximum received elongation at break is 200%. First block of this polymer contains 25% of lactide, has molar weight of 10000 Da. Second block is the pure polylactide, with molar weight 10000 Da. All the experimental results and mathematical modeling pointing direction to maximum elongation could be achieved by multi-block structures.</p>

scholarly journals Synthesis of Diblocks Copolymers PCL-b-PLLA and Optimization of its Mechanical Characteristics

2009 ◽  
Vol 11 (3) ◽  
pp. 239
Author(s):  
Vitali T. Lipik ◽  
Leonardus K. Widjaja ◽  
Sing S. Liow ◽  
Subramanian S. Venkatraman ◽  
Marc J.M. Abadie
Keyword(s):  
Mechanical Properties ◽  
Polymeric Materials ◽  
Maximum Load ◽  
Absolute Maximum ◽  
Elongation At Break ◽  
Block Polymer ◽  
Second Stage ◽  
Molar Weight ◽  
Block Structures ◽  
To Receive

<p align="LEFT">Biodegradable polymeric materials have a wide application in medicine, ecology and a number of other branches of industry. Overwhelming majority of such polymers is well exposed to the biodegradation, but they have mechanical properties which don’t correspond to the requirements of application areas. As a rule, these materials possess low elasticity. In this work, optimization of mechanical properties of biodegradable polymers and the search of structure of block polymer on the basis of ε-caprolactone and L-lactide with the maximal elasticity are considered. The purpose of the work is to receive the diblock polymer with mechanical properties as close as possible to elastomer for medical devices. The task is reached due to application of design of experiment with the subsequent optimization of the received results. Maximization of elongation at maximum load of received polymer is solved by the greatest possible reduction of crystallinity with a variation of molar weight of both part of diblock: polycaprolactone and polylactide. The absolute maximum of elongation at maximum load of synthesized diblock polymers is found. It is established that diblock with the following structure possesses the best mechanical properties in this class of polymers. Molar weight of the polycaprolactone block is 5000 Da while polylactide block is 7000 Da. Elongation at maximum load of this polymer was about 30%. In the second stage of our research, we try to improve the mechanical properties by making one block partly random (PCL-co-PLLA). Second block was made from homopolymer (PLLA). Maximum received elongation at break is 200%. First block of this polymer contains 25% of lactide, has molar weight of 10000 Da. Second block is the pure polylactide, with molar weight 10000 Da. All the experimental results and mathematical modeling pointing direction to maximum elongation could be achieved by multi-block structures.</p>

New Applications of Tire Powder Recycled by Micro-Waves

2020 ◽  
Vol 1012 ◽  
pp. 84-88
Author(s):  
Moises A. Canazza ◽  
Sandra R. Scagliusi ◽  
Hélio Wiebeck
Keyword(s):  
Mechanical Properties ◽  
Polymeric Materials ◽  
Elongation At Break ◽  
Rubber Powder ◽  
Physico Chemical ◽  
Elastomeric Materials ◽  
International Laws ◽  
Object Of Study ◽  
New Applications ◽  
Butadiene Styrene

In order to minimize impacts caused to environment and to save natural resources, especially from non-renewable sources, recycling of polymeric materials has been object of study. In this scenery, are included elastomeric materials, such as rubber, especially used in tires manufacturing, considering that pneumatic industry consumes around 60% of rubber production. Taking into account that final tires destination is a requirement based on norms and national and international laws, this work aims to the development of a study on the efficacy of micro-wave irradiation in the process of de-vulcanization of tire powder to be used in recycling. Tire powder was subjected to micro-wave irradiation and further merged to SBR (butadiene-styrene rubber) polymeric matrix, at 5, 15, 25 phr; after mixture, resulting compound was characterized for evaluation of physico-chemical and mechanical properties. For the assessment of all samples containing SBR and rubber powder there were applied following essays: Infra-red spectroscopy (FTIR), Tensile strength and elongation at break, Swelling Index. It was verified higher values for mechanical properties imparted by an increased quantity of rubber powder incorporated to SBR matrix.

scholarly journals Preparation of Biodegradable Materials by Reactive Extrusion

2008 ◽  
Vol 587-588 ◽  
pp. 520-524 ◽  
Author(s):  
Isabel Moura ◽  
Ana Vera Machado ◽  
Fernando M. Duarte ◽  
Gabriela Botelho ◽  
Regina Nogueira
Keyword(s):  
Mechanical Properties ◽  
High Density Polyethylene ◽  
Young Modulus ◽  
Polymeric Materials ◽  
Reactive Extrusion ◽  
Biodegradable Materials ◽  
Screw Extruder ◽  
Elongation At Break ◽  
Twin Screw ◽  
Poly Caprolactone

This work aimed to prepare biodegradable polymeric materials based on blends of a synthetic high density polyethylene (HDPE) and biodegradable polymers such as polylactic acid (PCL) and poly(caprolactone) (PLA), in a co-rotating twin-screw extruder. A polyethylene modified with maleic anhydride was used as compatibiliser. The mechanical results showed that the addition of PLA improves the blends stiffness while the addition of PCL leads to materials with a greater elongation at break and a lower Young modulus. This feature is related with the mechanical properties of each material as well as the adhesion between them. Concerning the biodegradability tests, it was found that HDPE/PCL blend presents the highest degree of biodegradability.

Structural features and strength behavior of TRIP/TWIP steels

2020 ◽  
pp. 5-18
Author(s):  
D. V. Prosvirnin ◽  
◽  
M. S. Larionov ◽  
S. V. Pivovarchik ◽  
A. G. Kolmakov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Thermomechanical Processing ◽  
Maximum Load ◽  
Structural Features ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Structural And Functional Properties ◽  
Twip Steels ◽  
The Creation

A review of the literature data on the structural features of TRIP / TWIP steels, their relationship with mechanical properties and the relationship of strength parameters under static and cyclic loading was carried out. It is shown that the level of mechanical properties of such steels is determined by the chemical composition and processing technology (thermal and thermomechanical processing, hot and cold pressure treatment), aimed at achieving a favorable phase composition. At the atomic level, the most important factor is stacking fault energy, the level of which will be decisive in the formation of austenite twins and / or the formation of strain martensite. By selecting the chemical composition, it is possible to set the stacking fault energy corresponding to the necessary mechanical characteristics. In the case of cyclic loads, an important role is played by the strain rate and the maximum load during testing. So at high loading rates and a load approaching the yield strength under tension, the intensity of the twinning processes and the formation of martensite increases. It is shown that one of the relevant ways to further increase of the structural and functional properties of TRIP and TWIP steels is the creation of composite materials on their basis. At present, surface modification and coating, especially by ion-vacuum methods, can be considered the most promising direction for the creation of such composites.

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 Anti-Inflammatory Properties of Injectable Betamethasone-Loaded Tyramine-Modified Gellan Gum/Silk Fibroin Hydrogels

Biomolecules ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1456
Author(s):  
Isabel Matos Oliveira ◽  
Cristiana Gonçalves ◽  
Myeong Eun Shin ◽  
Sumi Lee ◽  
Rui Luis Reis ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Mechanical Properties ◽  
Silk Fibroin ◽  
Therapeutic Efficacy ◽  
Composite Structures ◽  
Gelation Time ◽  
Polymeric Materials ◽  
Gellan Gum ◽  
Traditional Use

Rheumatoid arthritis is a rheumatic disease for which a healing treatment does not presently exist. Silk fibroin has been extensively studied for use in drug delivery systems due to its uniqueness, versatility and strong clinical track record in medicine. However, in general, natural polymeric materials are not mechanically stable enough, and have high rates of biodegradation. Thus, synthetic materials such as gellan gum can be used to produce composite structures with biological signals to promote tissue-specific interactions while providing the desired mechanical properties. In this work, we aimed to produce hydrogels of tyramine-modified gellan gum with silk fibroin (Ty–GG/SF) via horseradish peroxidase (HRP), with encapsulated betamethasone, to improve the biocompatibility and mechanical properties, and further increase therapeutic efficacy to treat rheumatoid arthritis (RA). The Ty–GG/SF hydrogels presented a β-sheet secondary structure, with gelation time around 2–5 min, good resistance to enzymatic degradation, a suitable injectability profile, viscoelastic capacity with a significant solid component and a betamethasone-controlled release profile over time. In vitro studies showed that Ty–GG/SF hydrogels did not produce a deleterious effect on cellular metabolic activity, morphology or proliferation. Furthermore, Ty–GG/SF hydrogels with encapsulated betamethasone revealed greater therapeutic efficacy than the drug applied alone. Therefore, this strategy can provide an improvement in therapeutic efficacy when compared to the traditional use of drugs for the treatment of rheumatoid arthritis.

scholarly journals Effect of Organic Modifier Types on the Physical–Mechanical Properties and Overall Migration of Post-Consumer Polypropylene/Clay Nanocomposites for Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1502
Author(s):  
Eliezer Velásquez ◽  
Sebastián Espinoza ◽  
Ximena Valenzuela ◽  
Luan Garrido ◽  
María José Galotto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Food Packaging ◽  
Clay Nanocomposites ◽  
Organic Modifier ◽  
Thermal And Mechanical Properties ◽  
Chemical Safety ◽  
Elongation At Break ◽  
Fatty Food ◽  
Recycled Plastics ◽  
Thermal Stability Of

The deterioration of the physical–mechanical properties and loss of the chemical safety of plastics after consumption are topics of concern for food packaging applications. Incorporating nanoclays is an alternative to improve the performance of recycled plastics. However, properties and overall migration from polymer/clay nanocomposites to food require to be evaluated case-by-case. This work aimed to investigate the effect of organic modifier types of clays on the structural, thermal and mechanical properties and the overall migration of nanocomposites based on 50/50 virgin and recycled post-consumer polypropylene blend (VPP/RPP) and organoclays for food packaging applications. The clay with the most hydrophobic organic modifier caused higher thermal stability of the nanocomposites and greater intercalation of polypropylene between clay mineral layers but increased the overall migration to a fatty food simulant. This migration value was higher from the 50/50 VPP/RPP film than from VPP. Nonetheless, clays reduced the migration and even more when the clay had greater hydrophilicity because of lower interactions between the nanocomposite and the fatty simulant. Conversely, nanocomposites and VPP/RPP control films exhibited low migration values in the acid and non-acid food simulants. Regarding tensile parameters, elongation at break values of PP film significantly increased with RPP addition, but the incorporation of organoclays reduced its ductility to values closer to the VPP.

scholarly journals Low-Temperature Mechanical Properties of High-Density and Low-Density Polyethylene and Their Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1821
Author(s):  
Ildar I. Salakhov ◽  
Nadim M. Shaidullin ◽  
Anatoly E. Chalykh ◽  
Mikhail A. Matsko ◽  
Alexey V. Shapagin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Impact Strength ◽  
Relative Elongation ◽  
High Density ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Elongation At Break ◽  
Subzero Temperatures ◽  
Izod Impact

Low-temperature properties of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and their blends were studied. The analyzed low-temperature mechanical properties involve the deformation resistance and impact strength characteristics. HDPE is a bimodal ethylene/1-hexene copolymer; LDPE is a branched ethylene homopolymer containing short-chain branches of different length; LLDPE is a binary ethylene/1-butene copolymer and an ethylene/1-butene/1-hexene terpolymer. The samples of copolymers and their blends were studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), 13С NMR spectroscopy, and dynamic mechanical analysis (DMA) using testing machines equipped with a cryochamber. It is proposed that such parameters as “relative elongation at break at −45 °C” and “Izod impact strength at −40 °C” are used instead of the ductile-to-brittle transition temperature to assess frost resistance properties because these parameters are more sensitive to deformation and impact at subzero temperatures for HDPE. LLDPE is shown to exhibit higher relative elongation at break at −45 °C and Izod impact strength at −20 ÷ 60 °C compared to those of LDPE. LLDPE terpolymer added to HDPE (at a content ≥ 25 wt.%) simultaneously increases flow properties and improves tensile properties of the blend at −45 °C. Changes in low-temperature properties as a function of molecular weight, MWD, crystallinity, and branch content were determined for HDPE, LLDPE, and their blends. The DMA data prove the resulting dependences. The reported findings allow one to understand and predict mechanical properties in the HDPE–LLDPE systems at subzero temperatures.

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