Thermal stability of surface-esterified cellulose and its composite with polyolefinic matrix
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Thermal stability of hydrophobized cellulose powders was investigated from the perspective of potential use as filler in non-polar polyolefinic matrix. The hydrophobization was done by heterogeneous esterification with three carboxylic acids which differ in chain length (3, 10 and 18 carbons). Data measured by means of thermogravimetry (TG) were recalculated according to model-free isoconversional method to construct time–temperature plots. It was demonstrated that the esterification significantly decreases thermal stability of the material, which reduces feasible processing window. Under non-oxidative atmosphere, the single-step decomposition of materials is prevailing, while the process is more complex in air. In both cases the oleic acid esters showed the lowest stability and the original cellulose was the most stable. Finally, all powders were compounded with polyethylene or polypropylene. Obtained composites were then subjected to color measurement and TG. Even though the materials were partly degraded, which was indicated by the yellowish hue of the composites, virtually no impact of the filler pyrolysis on the polymer matrix decomposition was observed, particularly in case of decanoyl esters.
KeywordsCellulose Esterification Hydrophobization Stability Degradation Composite
Authors gratefully acknowledge Mr. Radek Holubar for preparation of composites, Mr. Pavol Suly for his help with TG, Dr. Alena Kalendova for her assistance with initial FT-IR measurements, and Dr. Tomas Sedlacek for his help with supply of Arbocel®. All mentioned are from Tomas Bata University in Zlin. The work was supported by the Operational Programme Research and Development for Innovations cofounded by the European Regional Development Fund (ERDF) and national budget of Czech Republic within the framework of the Centre of Polymer Systems project (reg. no.: CZ.1.05/2.1.00/03.0111). Authors gratefully acknowledge also the financial support of this work by the internal grant of Tomas Bata University in Zlin, No. IGA/FT/2012/040 and No. IGA/FT/2013/012, funded from the resources of specific university research.
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