Proton-Conducting Cross-Linked Sulfonated Aromatic Polymers for Fuel Cells Application

2012 ◽  
Vol 1384 ◽  
Author(s):  
B. Maranesi ◽  
L. Pasquini ◽  
M. Khadhraoui ◽  
P. Knauth ◽  
M.L. Di Vona
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Hydrolytic Degradation ◽  
Exchange Capacity ◽  
Polymer Chains ◽  
Cross Linking ◽  
Ionic Exchange ◽  
Acid Base ◽  
Acid Base Titration ◽  
Aromatic Polymers

AbstractThermal stability, hydration and mechanical properties of thermally cross-linked Sulfonated Aromatic Polymers (SAP) with high ionic exchange capacity (IEC) were measured and compared to untreated samples. The formation of cross-linking greatly stabilizes SAP in terms of thermal, mechanical, and hydrolytic degradation: they can resist in water even at a temperature of 145 °C with improved mechanical properties. Acid-base titration and FTIR spectra consistently indicate that SAP microstructure stabilization is related to cross-linking of the polymer chains by SO2 bridges, which is promoted by temperature.

scholarly journals Enzymatic and Chemical Cross-Linking of Bacterial Cellulose/Fish Collagen Composites—A Comparative Study

2021 ◽  
Vol 22 (7) ◽  
pp. 3346
Author(s):  
Agata Sommer ◽  
Paulina Dederko-Kantowicz ◽  
Hanna Staroszczyk ◽  
Sławomir Sommer ◽  
Marek Michalec
Keyword(s):  
Thermal Stability ◽  
Bacterial Cellulose ◽  
Secondary Alcohol ◽  
Water Vapor Permeability ◽  
Polymer Chains ◽  
Cross Linking ◽  
Vapor Permeability ◽  
Covalent Bonds ◽  
Fish Collagen ◽  
Chemical Cross Linking

This article compares the properties of bacterial cellulose/fish collagen composites (BC/Col) after enzymatic and chemical cross-linking. In our methodology, two transglutaminases are used for enzymatic cross-linking—one recommended for the meat and the other proposed for the fish industry—and pre-oxidated BC (oxBC) is used for chemical cross-linking. The structure of the obtained composites is characterized by scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy, and their functional properties by mechanical and water barrier tests. While polymer chains in uncross-linked BC/Col are intertwined by H-bonds, new covalent bonds in enzymatically cross-linked ones are formed—resulting in increased thermal stability and crystallinity of the material. The C2–C3 bonds cleavage in D-glucose units, due to BC oxidation, cause secondary alcohol groups to vanish in favor of the carbonyl groups’ formation, thus reducing the number of H-bonded OHs. Thermal stability and crystallinity of oxBC/Col remain lower than those of BC/Col. The BC/Col formation did not affect tensile strength and water vapor permeability of BC, but enzymatic cross-linking with TGGS improved them significantly.

scholarly journals Alginate/Poly(γ-glutamic Acid) Base Biocompatible Gel for Bone Tissue Engineering

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Wing P. Chan ◽  
Fu-Chen Kung ◽  
Yu-Lin Kuo ◽  
Ming-Chen Yang ◽  
Wen-Fu Thomas Lai
Keyword(s):  
Mechanical Properties ◽  
Glutamic Acid ◽  
Blood Compatibility ◽  
Cross Linking ◽  
Temperature Sensitive ◽  
Minor Effect ◽  
Acid Base ◽  
A Minor ◽  
Sodium Form ◽  
Alginate Matrix

A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid), alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca2+from Ca–γ-PGA directly andγ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and forγ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials.

The Behaviour of Cross-Linking Filled PP to Micro-Indentation Test

2016 ◽  
Vol 368 ◽  
pp. 138-141
Author(s):  
Martin Ovsík ◽  
Vojtech Šenkeřík ◽  
David Manas ◽  
Miroslav Maňas ◽  
Michal Stanek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Beta Radiation ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
Depth Sensing ◽  
Surface Layers ◽  
Micro Indentation ◽  
Different Doses

Cross-linking is a process in which polymer chains are associated through chemical bonds. Radiation, which penetrated through specimens and reacted with the cross-linking agent, gradually formed cross-linking (3D net), first in the surface layer and then in the total volume, which resulted in considerable changes in specimen behaviour. The aim of the experiments was to study the influence of different doses of Beta radiation to the structure and micro-mechanical properties of polypropylene filled by 30% glass fiber (PP+GF). Hard surface layers of PP+GF can be formed by radiation cross-linking by β – radiation with doses of 33, 66 and 99 kGy. Material properties created by β – radiation are measured by micro-indentation test using the DSI method (Depth Sensing Indentation). Individual radiation doses caused structural and micro-mechanical changes which have a significant effect on the final properties of the PP+GF tested. Micro-mechanical properties increased with increasing value of the dose of irradiation material (increase about 49%). The changes were examined and confirmed by X-ray diffraction.

Irradiation of Polyamide Measured by Micro-Indentation Test

2015 ◽  
Vol 1120-1121 ◽  
pp. 1179-1182
Author(s):  
Martin Ovsik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Adam Skrobak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Material Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Cross Linking ◽  
Indentation Hardness ◽  
Chemical Bonds ◽  
Depth Sensing ◽  
Micro Indentation

Cross-linking is a process in which polymer chains are associated through chemical bonds. This research paper deals with the possible utilization of irradiated polyamide. Influence of the intensity of irradiation on micro-indentation hardness was investigated. Material properties created by β – radiation are measured by micro-indentation test using the DSI method (Depth Sensing Indentation). Hardness increased with increasing dose of irradiation at everything samples; however results of micro-indentation test shows increasing in micro-mechanical properties of surface layer. The highest values of micro-mechanical properties were reached radiation dose of 99 kGy, when the micro-mechanical values increased by about 18%.

Surface Properties of Crosslinking Polyamide Measured by Micro-Indentation Test

2018 ◽  
Vol 919 ◽  
pp. 111-119
Author(s):  
Martin Ovsik ◽  
Michal Stanek ◽  
Vojtech Senkerik
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Surface Properties ◽  
Electron Beam Irradiation ◽  
Indentation Test ◽  
Polymer Chains ◽  
Beta Radiation ◽  
Cross Linking ◽  
Micro Indentation ◽  
Different Doses

Cross-linking is a process in which polymer chains are associated through chemical bonds. Radiation, which penetrated through specimens and reacted with the cross-linking agent, gradually formed cross-linking (3D net), first in the surface layer and then in the total volume, which resulted in considerable changes in specimen behavior. This paper studies the effect of different doses of ionizing beta radiation on the micro-mechanical properties of commercially available polyamide. The measured results indicate, that electron beam irradiation is very effective tool for improvement of surface properties of PA6. In terms of micro-mechanical properties, the values of micro-hardness of surface layer increased by 24% at radiation dose of 132 kGy, stiffness of surface micro layer by 26% (132 kGy) as a result of different loads (0.5N and 2N). Improvement of micro-mechanical properties of radiated polyamide has a great significance also for industry. The modified polyamide shifts to the group of materials that have considerably better properties. Its micro-mechanical properties make polyamide ideal for a wide application in areas where higher resistance to wear, creep are required. Commonly manufactured PA6 can hardly fulfil these criteria.

scholarly journals Anisotropic magnetic hydrogels: design, structure and mechanical properties

2019 ◽  
Vol 377 (2143) ◽  
pp. 20180217 ◽  
Author(s):  
Cristina Gila-Vilchez ◽  
Mari C. Mañas-Torres ◽  
Rafael Contreras-Montoya ◽  
Miguel Alaminos ◽  
Juan D. G. Duran ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Biomedical Applications ◽  
Magnetic Particles ◽  
Precursor Solution ◽  
Polymer Chains ◽  
Cross Linking ◽  
Theme Issue ◽  
Design Structure ◽  
Internal Structures ◽  
Intrinsic Feature

Anisotropy is an intrinsic feature of most of the human tissues (e.g. muscle, skin or cartilage). Because of this, there has been an intense effort in the search of methods for the induction of permanent anisotropy in hydrogels intended for biomedical applications. The dispersion of magnetic particles or beads in the hydrogel precursor solution prior to cross-linking, in combination with applied magnetic fields, which gives rise to columnar structures, is one of the most recently proposed approaches for this goal. We have gone even further and, in this paper, we show that it is possible to use magnetic particles as actuators for the alignment of the polymer chains in order to obtain anisotropic hydrogels. Furthermore, we characterize the microstructural arrangement and mechanical properties of the resulting hydrogels. This article is part of a theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’.

Effects of Starting Compositions on the Properties of Methylsilsesquioxane Aerogels

2010 ◽  
Vol 1247 ◽  
Author(s):  
Gen Hayase ◽  
Kazuyoshi Kanamori ◽  
Kazuki Nakanishi ◽  
Teiichi Hanada
Keyword(s):  
Mechanical Properties ◽  
Phase Separation ◽  
Energy Savings ◽  
Sol Gel ◽  
Light Transmittance ◽  
Cross Linking ◽  
Methyl Groups ◽  
Acid Base ◽  
Control Phase ◽  
Composition Properties

AbstractRecent years, although silica aerogel is expected to be the material for energy savings, the lack of the strength prevents from commercial usages such as heat-insulating windows. To improve mechanical properties, methyltrimethoxysilane is used as a precursor of aerogels because the network becomes flexible due to the relatively low cross-linking density and to the unreacted methyl groups. Because of the strong hydrophobicity of MTMS-derived condensates, uniform and homogeneous gel networks are hardly attained. In this study, we employed surfactant n-hexadecyltrimethylammonium chloride (CTAC) in starting compositions to control phase separation during a 2-step acid/base sol-gel reaction. By changing the starting composition, properties of aerogels such as bulk density and light transmittance are affected. With increasing amount of CTAC, the gel networks became denser and less transparent. Highly transparent aerogels were obtained when the amount of urea was increased.

Micro-Indentation Test and Morphology of Electron Beam Irradiated HDPE

2015 ◽  
Vol 662 ◽  
pp. 189-192
Author(s):  
Martin Ovsik ◽  
Petr Kratky ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Cross Linking ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
Irradiation Dosage ◽  
The Cross ◽  
Micro Indentation ◽  
Different Doses

Cross-linking is a process in which polymer chains are associated through chemical bonds. The cross-linking level can be adjusted by the irradiation dosage and often by means of a cross-linking booster. The polymer additional cross-linking influences the surface nanoand micro layers in the way comparable to metals during the thermal and chemical-thermal treatments. The aim of this paper is to study the effect of ionizing radiation with different doses (33, 66 and 99 kGy), on micro-mechanical properties of polyethylene (HDPE) and compare these results with those of non-irradiated samples. Influence of the cross-linking by β – radiation of the tested HDPE on micro-indentation test and morphology was investigated. Micro-mechanical properties increased with increasing value of the dose of irradiation material. The changes were examined and confirmed by X-ray diffraction.

scholarly journals LOCAL NANO-MECHANICAL PROPERTIES OF CROSS-LINKED POLYBUTYLENE

2020 ◽  
Vol 27 ◽  
pp. 112-115
Author(s):  
Martin Ovsík ◽  
Michal Staněk ◽  
Adam Dočkal ◽  
Petr Fluxa
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Polymer Chains ◽  
Cross Linking ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Depth Sensing ◽  
Polybutylene Terephthalate ◽  
3D Network ◽  
Irradiation Dosage

Cross-linking is a process in which polymer chains are associated through chemical bonds. The cross-linking level can be adjusted by the irradiation dosage and often by means of a cross-linking booster. The polymer additional cross-linking influences the surface nano and micro layers in the way comparable to metals during the thermal and chemical-thermal treatments. Polybutylene terephthalate (PBT) can be found in a group of structural polymers, which are often used in industry, especially in automotive. Applying the technology of electron radiation induces a creation of 3D network structure, which improves the local mechanical properties. These were later measured by a depth sensing indentation (DSI) test. This state of the art method is based on immediate detection of indentation depth in relation to applied force. The creation of 3D network caused an increase in nano-mechanical properties values, such as indentation hardness and indentation modulus, in comparison to the virgin material. The indentation hardness rose by 80%, while the indentation modulus elevated by 62%. The selected structural materials, e.g. PBT, were modified by the electron irradiation in a positive way and as such could be moved to a group of high performance materials.

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