Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Non-isothermal melt- and cold-crystallization, melting process, and optical and mechanical properties of PLLA: the effect of TAPH

Huang Hao, Lv Yang, Zhao Lisha, Tan Ninghui, Cai Yanhua

Materials Science Poland

2024

Vol. 42, No. 2

100--112

We synthesized a new phenylacetic hydrazide derivative (TAPH) by acylation and amination to prepare modified poly(L-lactide) (PLLA) materials. The non-isothermal melt- and cold-crystallization, melting process, optical and mechanical properties of modified PLLA were studied with the objective of correlating TAPH to PLLA crystallization and other performances. Non-isothermal melt crystallization showed that TAPH as a heterogeneous additive was able to promote crystallization and accelerate the crystallization rate of PLLA. Unfortunately, an increase in the cooling rate during cooling led to a decrease in crystallization ability. Non-isothermal cold-crystallization results disclosed that PLLA/TAPH’s coldcrystallization behavior depended on the heating rate; and upon a given heating rate, with an increase in TAPH loading, a shift toward the low-temperature side of the cold-crystallization peak further confirmed the nucleation effect of TAPH. The melting processes of PLLA/TAPH effectively depended on TAPH, the heating rate, and previous crystallization behaviors including non-isothermal crystallization and isothermal crystallization. Additionally, the double-melting peaks that appeared during the melt were thought to be due to melting-recrystallization. In terms of the optical property, the influence of TAPH on PLLA’s transparency was extremely negative as 2 wt% TAPH caused PLLA’s transparency to be zero. A comparative study on mechanical properties showed that TAPH could enhance PLLA’s tensile modulus and tensile strength, but elongation at break of any PLLA/TAPH was lower than that of pure PLLA.

Thermal properties and processability of modified poly(L-lactide): the role of phenylacetic acid hydrazide derivative

Huang Hao, Cai Yanhua, Zhao Lisha

Polimery

2022

Vol. 67, nr 9

423--432

The influence of phenylacetic acid hydrazide (NAPAH) derivative content, melt temperature (170−200°C) and cooling rate (1−20°C/min) on poly(L-lactide) (PLLA) nucleation were investigated. Increasing the content of NAPAH (0.5−3.0 wt.%) had a positive effect on PLLA crystallization, while an increase in the cooling rate and heating temperature had a negative effect. In the case of isothermal crystallization carried out for a long time (180 min), the melting process depended only on the crystal lization temperature. NAPAH also influenced the cold crystallization temperature, reduced thermal stability and improved PLLA processability (MFR).

Zbadano wpływ zawartości pochodnej hydrazydu kwasu fenylooctowego (NAPAH), temperatury stopu (170−200°C) i szybkości chłodzenia (1–20°C/min) na nukleację poli(L-laktydu) (PLLA). Zwiększenie zawartości NAPAH (0,5–3,0% mas.) miało pozytywny wpływ na krystalizację PLLA, natomiast wzrost szybkości chłodzenia i temperatury ogrzewania negatywny. W przypadku krystalizacji izotermicznej prowadzonej przez długi czas (180 min), proces topnienia zależał tylko od temperatury krystalizacji. NAPAH wpływał również na temperaturę zimnej krystalizacji, zmniejszał stabilność ter miczną i poprawiał właściwości przetwórcze PLLA (MFR).