A study on the melting and crystallization of polyoxymethylene‐copolymer/hydroxyapatite nanocomposites. (27th November 2012)

• Record Type: Journal Article
• Authors: Pielichowska, Kinga; Dryzek, Ewa; Olejniczak, Zbigniew; Pamuła, Elżbieta; Pagacz, Joanna
• Is Part Of: Polymers for advanced technologies. Volume 24:Number 3(2013:Mar.)
• Page Start: 318
• Page End: 330
• Publication Date: 2012-11-27
• Subjects: Polymers -- Periodicals; 668.9
• DOI: 10.1002/pat.3086
• Languages: English
• ISSNs: 1042-7147

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>In this work, isothermal crystallization kinetics of polyoxymethylene copolymer (POM) in POM/hydroxyapatite (HAp) nanocomposites has been investigated. Melting behavior and crystalline structure formation were studied using TOPEM DSC, positron lifetime spectroscopy (PALS), atomic force microscopy (AFM) and <sup>13</sup>C and <sup>31</sup>P solid‐state NMR. The highest degree of crystallinity was found for POM/0.5% HAp nanocomposite and the lowest for POM/2.5% HAp. Isothermal crystallization analysis showed that an introduction of HAp nanoparticles led to effective heterogeneous nucleation and formation of crystals with higher Avrami exponent. Besides, changes in overall crystallization rate were observed – the highest overall crystallization rate was found for POM/0.5% HAp sample, while the lowest for POM/2.5% HAp was observed. Generally, for POM in POM/HAp nanocomposites, a significant decrease in nucleation activation energy (<italic>K<sub>g</sub></italic>), and the fold surface free energy (<italic>σ<sub>e</sub></italic>) was found. For nanocomposite containing 2.5% HAp, heterogeneous nucleation takes place as well, but too high concentration of nanoparticles hinders POM crystallization and enhances formation of more defected crystals as confirmed by AFM data. The presence of HAp nanoparticles in the POM matrix was confirmed by <sup>31</sup>P MAS‐NMR, but their influence on the crystallization process was not observed in the <sup>13</sup>C CP‐MAS‐NMR spectra. Copyright © 2012 John Wiley & Sons, Ltd.</p> </abstract>