Thermostabilising and nucleating effect of montmorillonite on polyoxymethylene

Abstract

A series of alkyl ammonium/montmorillonite (MMT) organoclays were selected and melt blended with polyoxymethylene (POM) to explore the effect of MMT on the thermostability and mechanical properties of POM. The effects of the nature of the surfactants used in MMT modification on the intercalation of POM chains within the silicate galleries, the interfacial compatibility of POM/MMT and the thermostability of the composites were studied. The POM/MMT composites were prepared via melt, solution, solid state pan milling and in situ intercalative polymerisation blending method respectively, and the effects of preparation methods on the dispersion and exfoliation of MMT in POM matrix were measured by the wide angle X-ray scattering analysis. The thermal stabilisation effect of MMT on POM was studied by the isothermal weight loss analysis, thermogravimetric analysis (TGA) and formaldehyde emission amount measurement (FEA), which showed that a proper type and content of surfactant modified MMT may endow POM with improved thermostability. The crystallisation behaviour of POM/MMT composite was studied by the methods of polarised light microscopy (PLM), isothermal and non-isothermal crystallisation, which showed that a proper type and content of MMT had remarkable nucleation effect on POM and can improve the mechanical properties of POM efficiently.

The influence of polyoxymethylene molar mass on the oxidative thermal degradation of its nanocomposites with hydroxyapatite

“…It should be noted that lower activation energy for POM degradation with autocatalysis model for T2/10 % HAp and T3/10 % HAp composites in comparison with T2 and T3 copolymers was found. This effect can be attributed to the The influence of polyoxymethylene molar mass on the oxidative thermal degradation of its… 759 catalytic influence of HAp and formaldehyde which formation is accelerated by HAp presence, on POM degradation process [31][32][33].…”

Nano-Scale Reinforcing and Toughening Thermoplastics: Processing, Structure and Mechanical Properties

“…www.intechopen.com 4.1.6 Thermo-oxidative properties It has been reported that by adding inorganic fillers (Sun et al, 2007), may increase the thermal stability of thermoplastics. This is at odds with our TGA observation.…”

Nanocomposites of Polyoxymethylene

“…Higher covering of MMT surface with alkyl chains that were introduced with quaternary ammonium salt masked the polar surface of mineral and hindered the formation of stronger interaction between functional groups on the silicate surface and ether linkage in POM macromolecules. Sun et al prepared the POM/MMT composites via four diff erent techniques: direct melt blending and melt blending of POM/MMT masterbatches prepared by solution intercalation, solid-state pan milling and in situ intercalative polymerization [28]. Th ey also applied diff erent ammonium surfactants for improving the compatibility of layered silicates with POM.…”

“…Lamellar pathways were found to grow around the dispersed silicate layers of MMT, losing the symmetrical crystallite formation. Sun et al reported that the addition of MMT restrained the formation of large spherulites and refi ned POM crystal grain [28]. Moreover, MMT led to the rise of the crystallization and melting temperature, the decrease in the crystallization half peak width and increase in the crystallinity.…”

“…Sun et al observed that thermal stability was critically dependent on the molecular structure of ammonium surfactant and content of OMMT [28]. When the content of MMT was above 0,5 wt%, POM decomposed intensively so that extrusion was seriously disturbed by evolution of irritating formaldehyde.…”