Properties of poly(L-lactide) composites with different amount of surface modified magnesium hydroxide
| Autor: | Prnjak, Petra |
|---|---|
| Přispěvatelé: | Andričić, Branka |
| Jazyk: | chorvatština |
| Rok vydání: | 2018 |
| Předmět: |
toplinska svojstva polimera
entalpija taljenja polymer composites TEHNIČKE ZNANOSTI. Kemijsko inženjerstvo poli(L-laktid)(PLLA) polimerni kompoziti poly(L-lactide)(PLLA) DSC brucite thermal properties of polymers TECHNICAL SCIENCES. Chemical Engineering magnezijev hidroksid brucit enthalpy of melting magnesium hydroxide |
| Popis: | U ovom radu istraživan je utjecaj dodatka magnezijeva hidroksida Mg(OH) 2 na kristalnost i toplinske prijelaze (staklište, talište) poli(L-laktida) (PLLA). Magnezijev hidroksid je prethodno modificiran stearinskom kiselinom (udio stearinske kiseline 4, 6, 8%). Uzorci PLLA/Mg(OH) 2 masenih omjera 90/10, 85/15 i 80/20 pripravljeni su suhim miješanjem, a zatim ekstrudiranjem. Primjenom diferencijalne pretražne kalorimetrije određeni su toplinski prijelazi (staklište, talište), a temeljem entalpije taljenja izračunata je kristalnost PLLA. Utvrđeno je da dodatak Mg(OH) 2 uzrokuje porast staklišta PLLA, ali taj porast ne ovisi o udjelu Mg(OH) 2 i njegovoj površinskoj modifikaciji stearinskom kiselinom. Zbog porasta staklišta PLLA smanjuje se gibljivost segmenata makromolekula te se time otežava kristalizacija. Ovim mjerenjem je utvrđeno da PLLA kompoziti koji imaju veći udjel Mg(OH) 2 imaju manji stupanj kristalnosti. Izvorni PLLA ima talište koje karakterizira jedan pik, dok PLLA u kompozitu ima dva pika taljenja. In this thesis the influence of adding magnesium hydroxide Mg(OH) 2 to the poly (L-lactide) (PLLA) thermal transitions (glass transition, T g and melting temperature, T m ) was investigated. Magnesium hydroxide was previously modified with stearic acid (the fraction of stearic acid was 4, 6, 8 %). Samples of PLLA/Mg(OH) 2 with mass fraction 90/10, 85/15 and 80/20 were prepared by dry mixing and then by extrusion. Using differential scanning calorimetry, the glass transition and melting point temperatures as well as the PLLA crystallinity were determined. It was found that the addition of Mg(OH) 2 causes an increase in PLLA T g , but this increase does not depend on the fraction of Mg(OH) 2 and its surface modification with stearic acid. Due to the increase of T g , the macromolecular motionsare reduced, making it more difficult to crystallize. By this measurement, it was found that PLLA in composites having a higher content of Mg(OH) 2 have a lower degree of crystallinity. The original PLLA has a melting point characterized by one peak, while the PLLA in the composite has two melting peaks. |
| Databáze: | OpenAIRE |
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