Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: hexamethylene diisocyanate

Sortuj według:

Ogranicz wyniki do:

Biobased poly(3-hydroxybutyrate acid) composites with addition of aliphatic polyurethane based on polypropylene glycols

Zarzyka Iwona, Czerniecka-Kubicka Anna, Hęclik Karol, Dobrowolski Lucjan, Krzykowska Beata, Białkowska Anita, Bakar Mohamed

Acta of Bioengineering and Biomechanics

2022

Vol. 24, no. 1

75--89

Poly(3-hydroxybutyrate) (P3HB) is the most important of the polyhydroxyalkanoates. It is biosynthesized, biodegradable, biocompatible, and shows no cytotoxicity and mutagenicity. P3HB is a natural metabolite in the human body and, therefore, it could replace the synthetic, hard-to-degrade polymers used in the production of implants. However, P3HB is a brittle material with limited thermal stability. Therefore, in order to improve its mechanical properties and processing parameters by separating its melting point and degradation temperature, P3HB-based composites can be produced using, for example, linear aliphatic polyurethanes as modifiers. The aim of the study is a modification of P3HB properties with the use of linear aliphatic polyurethanes synthesized in reaction of hexamethylene diisocyanate (HDI) and polypropylene glycols (PPG) by producing their composites. Prepared biocomposites were tested by the scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Furthermore, selected mechanical properties were evaluated. It has been confirmed that new biocomposites showed an increase in impact strength, relative strain at break, decrease of hardness and higher degradation temperature compared to the unfilled P3HB. The biocomposites also showed a decrease in the glass transition temperature and the degree of crystallinity. Biocomposites obtained with 10 wt.% polyurethane synthesized with polypropylene glycol having 1000 g · mole–1 and HDI have the best thermal and mechanical properties.

Synthesis and characterization of new poly(azomethine-urethane) and polyphenol derivatives obtained from 3,4-dihydroxy benzaldehyde and hexamethylene diisocyanate

Kaya I., Kamaci M.

Polimery

2011

T. 56, nr 10

721-733

Oligophenol based poly(azomethine-urethane)s (PAMUs) including azomethine linkages were synthesized in three steps. At the first step, polyurethane (PUR) was synthesized in the copolymerization reaction of 3,4-dihydroxy benzaldehyde with hexamethylene diisocyanate (HDI) under the argon atmosphere. At the second step, the PAMUs were obtained by graft copolymerization of the preformed PUR with aminophenol (2-aminophenol, 3-aminophenol, or 4-aminophenol). At the last step, the obtained PAMUs were converted to their polyphenol derivatives via oxidative polycondensation reaction. The structures of the obtained compounds were confirmed by FT-IR, UV-vis, 1H NMR, and 13C NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined with the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TGA, DTA, and DSC. Fluorescence measurements were carried out in various concentrated dimethylformamide solutions to determine the optimum concentrations to obtain the maximal fluorescence intensities.

Poli(azometino-uretany) (PAMU) zawierające ugrupowania azometinowe syntezowano w trzech etapach. Pierwszy etap to reakcja kopolimeryzacji 3,4-dihydroksybenzaldehydu z diizocyjanianem heksametylenu (HDI) w atmosferze argonu, w której otrzymuje się poliuretan (PUR). W reakcji kopolimeryzacji szczepionej PUR z aminofenolem (2-aminofenolem, 3-aminofenolem lub 4-aminofenolem) stanowiącej drugi etap powstają PAMU, które następnie są przekształcane do odpowiednich pochodnych polifenolu w procesie polikondensacji utleniającej (schemat A). Strukturę otrzymanych związków potwierdzono metodami FT-IR, UV-vis, 1H NMR i 13C NMR (rys. 1—6). Za pomocą chromatografii żelowej (SEC) określano również parametry rozkładu ciężaru cząsteczkowego (tabela 3). Scharakteryzowano także rozpuszczalność zsyntetyzowanych związków w szeregu wybranych rozpuszczalników oraz zbadano ich stabilność termiczną metodami TGA, DTA i DSC (rys. 9, tabele 5 i 6). Przeprowadzono badania fluorescencji roztworów otrzymanych polimerów w dimetyloformamidzie, co umożliwiło wyznaczenie optymalnego stężenia tych roztworów pozwalające na uzyskanie maksymalnej intensywności fluorescencji (tabela 4).