Ageing of PA 11 Pipes in CO2 Medium: A Tool to Predict Their Residual Lifetime

2002 ◽  
Author(s):  
F. Thominette ◽  
I. Merdas ◽  
J. Verdu
Keyword(s):  
Kinetic Model ◽  
Computer Program ◽  
Acid Medium ◽  
Molar Mass ◽  
Catalytic Effect ◽  
Hydrolysis Reaction ◽  
High Conversion ◽  
Residual Lifetime ◽  
Average Molar Mass ◽  
Polyamide 11

The study of polyamide 11 hydrolysis in acid medium has a great importance taking into account the presence of CO2 pressure in the fields. Experimentally we have put in evidence that CO2 accelerates PA 11 hydrolysis and shift the equilibrium towards high conversions. Theoretically, two mechanisms can be involved in the CO2 effect on hydrolysis: - a catalytic effect by H+ ions (acceleration of the hydrolysis reaction); - an amine scavenging by CO2 (shift of the equilibrium towards high conversion) From this mechanistic scheme we propose a kinetic model. Then, we have built a computer program allowing to made all the calculations needed in practice by the users as the average molar mass and the residual lifetime for given conditions.

Inter-laboratory evaluation of SEC-post-column calcofluor for determination of the weight-average molar mass of cereal β-glucan

2015 ◽  
Vol 124 ◽  
pp. 254-264 ◽  
Author(s):  
Anne Rieder ◽  
Svein Halvor Knutsen ◽  
Ann-Sissel T. Ulset ◽  
Bjørn E. Christensen ◽  
Roger Andersson ◽  
...  
Keyword(s):  
Molar Mass ◽  
Laboratory Evaluation ◽  
Average Molar Mass

scholarly journals Determination of the Average Molar Mass of the Vapour Above Molten Sodium Chloride by the Transpiration Method.

1979 ◽  
Vol 33a ◽  
pp. 407-412 ◽  
Author(s):  
Halvor Kvande ◽  
Oldrich Strouf ◽  
Pär Svanström ◽  
Elina Näsäkkälä ◽  
Eberhard Hoyer ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Molar Mass ◽  
Average Molar Mass ◽  
Molten Sodium ◽  
Transpiration Method

The effect of polymer branching and average molar mass on the formation, stabilization and thermoresponsive properties of gold nanohybrids stabilized by poly(N-isopropylacrylamides)

2015 ◽  
Vol 6 (32) ◽  
pp. 5838-5850 ◽  
Author(s):  
Hong Hanh Nguyen ◽  
Annie Brûlet ◽  
Dominique Goudounèche ◽  
Pascale Saint-Aguet ◽  
Nancy Lauth-de Viguerie ◽  
...  
Keyword(s):  
Molar Mass ◽  
Average Molar Mass

The architecture of PNIPAM based polymers strongly influences both their thermoresponsiveness and their abilities to control and stabilize AuNP formation.

scholarly journals Hyaluronic Acid in the Intestinal Tract: Influence of Structure, Rheology, and Mucoadhesion on the Intestinal Uptake in Rats

Biomolecules ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1422
Author(s):  
Alexandro Barbosa de Souza ◽  
Marco Vinícius Chaud ◽  
Thais Francine Alves ◽  
Juliana Ferreira de Souza ◽  
Maria Helena Andrade Santana
Keyword(s):  
Hyaluronic Acid ◽  
Intestinal Tract ◽  
Molar Mass ◽  
Hydrodynamic Diameter ◽  
Average Molar Mass ◽  
Intestinal Membrane ◽  
Mixed Formulations ◽  
Jejunum Segment

Oral hyaluronic acid (HA) is a ubiquitous biopolymer that has gained attention as a treatment for local or systemic diseases. Here, we prepared and characterized structures of free HA (f-HA) with a high (>105 Da), intermediate (≤105 Da), and low (≤104 Da) average molar mass (MM); nanoparticles crosslinked with adipic dihydrazide (n-HA); and mixed formulations (mixed-HA) containing f-HA and n-HA. MM distribution determined the structure, hydrodynamic diameter, and zeta potential of the f-HAs. Crosslinking changed the physicochemical properties in n-HA. In vitro tack adhesion assays, using mucin tablets or a viable rat intestinal mucosa, showed better mucoadhesion with f-HA (intermediate MM) and mixed-HA (25% n-HA), especially in the jejunum segment. High MM f-HA presented negligible mucoadhesion. n-HA showed the deepest diffusion into the porous of the membranes. In vivo results showed that, except for high MM f-HA, there is an inverse relationship between rheological changes in the intestinal membrane macerates resulting from mucoadhesion and the effective intestinal permeability that led to blood clearance of the structures. We conclude that the n-HA formulations are promising for targeting other tissues, while formulations of f-HA (intermediate MM) and mixed-HA are better for treating dysbiosis.

scholarly journals The investigations of bioactive copper(II) complexes with reduced low-molar dextran

2008 ◽  
Vol 22 (2-3) ◽  
pp. 177-185 ◽  
Author(s):  
Milorad Cakić ◽  
Žarko Mitić ◽  
Goran S. Nikolić ◽  
Ljubomir Ilić ◽  
Goran M. Nikolić
Keyword(s):  
Fourier Transform ◽  
Complex Formation ◽  
Room Temperature ◽  
Molar Mass ◽  
Reaction Conditions ◽  
Average Molar Mass ◽  
Square Planar ◽  
Physicochemical Methods ◽  
Fourier Transform Ir ◽  
Aqueous Complexes

The optimization of the reaction conditions (pH,T,t) to obtain stable copper(II) ion complexes with dextran derivatives were investigated in this paper. A complete synthesis of stable aqueous complexes can be realized with reduced low-molar polysaccharides, at an average molar mass 5000 g mol–1and pH 7.5–8. Fourier-transform IR spectra of polysaccharide dextran and its compounds with copper(II) ion, recorded at room temperature, were analyzed in order to obtain the information about the structure and the conformation of these polymer compounds. The ESR parameters of the spectra indicate the square-planar coordination of Cu(II) ion with four O atoms. Copper(II) complex formation with dextran and its derivatives were analyzed by physicochemical methods. Synthesized complexes of Cu(II) ion with reduced low-molar dextran in comparison with commercial preparations showed the considerably lower acute toxicity (LD501705).

scholarly journals Quantification of Polyphenols in Seaweeds: A Case Study of Ulva intestinalis

Antioxidants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 612 ◽  
Author(s):  
Marie Emilie Wekre ◽  
Karoline Kåsin ◽  
Jarl Underhaug ◽  
Bjarte Holmelid ◽  
Monica Jordheim
Keyword(s):  
Gallic Acid ◽  
Qualitative Data ◽  
Molar Mass ◽  
Total Phenolic ◽  
Special Importance ◽  
Average Molar Mass ◽  
Complex Samples ◽  
Ulva Intestinalis ◽  
Polyphenolic Profile

In this case study, we explored quantitative 1H NMR (qNMR), HPLC-DAD, and the Folin-Ciocalteu assay (TPC) as methods of quantifying the total phenolic content of a green macroalga, Ulva intestinalis, after optimized accelerated solvent extraction. Tentative qualitative data was also acquired after multiple steps of purification. The observed polyphenolic profile was complex with low individual concentrations. The qNMR method yielded 5.5% (DW) polyphenols in the crude extract, whereas HPLC-DAD and TPC assay yielded 1.1% (DW) and 0.4% (DW) respectively, using gallic acid as the reference in all methods. Based on the LC-MS observations of extracts and fractions, an average molar mass of 330 g/mol and an average of 4 aromatic hydrogens in each spin system was chosen for optimized qNMR calculations. Compared to the parallel numbers using gallic acid as the standard (170 g/mol, 2 aromatic H), the optimized parameters resulted in a similar qNMR result (5.3%, DW). The different results for the different methods highlight the difficulties with total polyphenolic quantification. All of the methods contain assumptions and uncertainties, and for complex samples with lower concentrations, this will be of special importance. Thus, further optimization of the extraction, identification, and quantification of polyphenols in marine algae must be researched.

scholarly journals Synthesis, Characterization, and Osteoblastic Cell Culture of Poly(L-co-D,L-lactide-co-trimethylene carbonate) Scaffolds

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
André Dutra Messias ◽  
Kelly Fernanda Martins ◽  
Adriana Cristina Motta ◽  
Eliana Aparecida de Rezende Duek
Keyword(s):  
Tissue Engineering ◽  
Cell Culture ◽  
Glass Transition ◽  
Bone Tissue Engineering ◽  
Molar Mass ◽  
Bulk Polymerization ◽  
Osteoblastic Cell ◽  
Trimethylene Carbonate ◽  
Average Molar Mass ◽  
Copolymer Poly

Lactide-based polymers have been widely investigated as materials for tissue engineering. However, characteristics such as low flexibility and elongation tend to limit particular applications, although these can be enhanced by adding plasticizers such as trimethylene carbonate (TMC) to the polymer chain of the copolymer poly(L-lactide-co-D,L-lactide) (PLDLA). The aim of this work was to synthesize and characterize a terpolymer of L-lactide, D,L-lactide, and TMC. The polymers were synthesized from 30% TMC by bulk polymerization and resulted in an average molar mass >105 g/mol. Thermal investigation of PLDLA-TMC showed a decrease in the glass transition and onset temperatures compared to PLDLA. PLDLA-TMC scaffolds stimulated the proliferation and normal phenotypic manifestations of cultured osteoblasts. These results show that it was possible to produce a terpolymer from L-lactide, D,L-lactide, and TMC. Scaffolds of this terpolymer had important characteristics that could be useful for applications in bone tissue engineering.

Dependence of the zero shear-rate viscosity and the viscosity function of linear high-density polyethylenes on the mass-average molar mass and polydispersity

2005 ◽  
Vol 45 (5) ◽  
pp. 755-764 ◽  
Author(s):  
Florian J. Stadler ◽  
Christian Piel ◽  
Joachim Kaschta ◽  
Sascha Rulhoff ◽  
Walter Kaminsky ◽  
...  
Keyword(s):  
Shear Rate ◽  
Molar Mass ◽  
High Density ◽  
Average Molar Mass ◽  
Viscosity Function
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