Thermoplastic resin transfer molding (T-RTM) technology was applied to synthesize graphene nanoplatelets-based nanocomposites via anionic ring-opening polymerization (AROP). Polyamide 6 (PA6) was obtained by AROP and was used as the polymeric matrix of the developed nanocomposites. The non-isothermal crystallization behavior of PA6 and nanocomposites was analyzed by differential scanning calorimetry (DSC). Nanocomposites with 0.5 wt.% of graphene nanoplatelets (GNPs) with two different diameter sizes were prepared. Results have shown that the crystallization temperature shifted to higher values in the presence of GNPs. This behavior is more noticeable for the nanocomposite prepared with smaller GNPs (PA6/GN). The crystallization kinetic behavior of all samples was assessed by Avrami and Liu's models. It was observed that GNPs increased the crystallization rate, thus revealing a nucleating ability, and also validated the reduction of half-time crystallization values. Such tendency was also supported by the lower activation energy values determined by Friedman's method.
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http://dx.doi.org/10.3390/polym15204109 | DOI Listing |
Molecules
January 2025
Department of Physical Chemistry, Faculty of Chemical Technology, University of Pardubice, nam. Cs Legii 565, 532 10 Pardubice, Czech Republic.
The particle size-dependent processes of structural relaxation and crystal growth in amorphous nifedipine were studied by means of non-isothermal differential scanning calorimetry (DSC) and Raman microscopy. The enthalpy relaxation was described in terms of the Tool-Narayanaswamy-Moynihan model, with the relaxation motions exhibiting the activation energy of 279 kJ·mol for the temperature shift, but with a significantly higher value of ~500 kJ·mol being obtained for the rapid transition from the glassy to the undercooled liquid state (the latter is in agreement with the activation energy of the viscous flow). This may suggest different types of relaxation kinetics manifesting during slow and rapid heating, with only a certain portion of the relaxation motions occurring that are dependent on the parameters of a given temperature range and time frame.
View Article and Find Full Text PDFPolymers (Basel)
December 2024
State Key Laboratory of Organic-Inorganic Composites, Beijing Laboratory of Biomedical Materials, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
A series of polyurethanes (PU-GT) were prepared using polyglycolide-block-polytetrahydrofuran-block-polyglycolide (PGA-PTHF-PGA), polytetrahydrofuran homopolymer (PTHF), glycerol, and hexamethylene diisocyanate (HDI) by a one-pot synthesis method. The non-isothermal crystallization and subsequent heating curves showed that the PTHF component in these polyurethanes could crystallize in a temperature range of -11.5~2.
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November 2024
Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan, Poland.
Biogenic silica (SiO) sourced from living organisms, especially plants such as rice and other cereals, has recently been successfully applied in different polymeric compositions. Another rich source of biogenic silica is common horsetail ( L.), containing up to 25% SiO in the dry matter.
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November 2024
College of Science, Nanchang Institute of Technology, Nanchang 330099, China.
Polylactic acid (PLA) is a widely recognized biodegradable polymer. However, the slow crystallization rate of PLA restricts its practical applications. In this study, camphor leaf biochar decorated with multi-walled carbon nanotubes (C@MWCNTs) was prepared using the strong adhesive properties of polydopamine, and PLA/C@MWCNTs composites were fabricated via the casting solution method.
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November 2024
Metallurgy and Materials Engineering Department, Engineering Faculty, Esentepe Campus, Sakarya University, 54187 Sakarya, Türkiye.
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