Dispersion and Reinforcing Potential of Carboxymethylated Nanofibrillated Cellulose Powders Modified with 1-Hexanol in Extruded Poly(Lactic Acid) (PLA) Composites

Journal of Polymers and the Environment - Tập 20 - Trang 1052-1062 - 2012
C. Eyholzer1,2, P. Tingaut1, T. Zimmermann1, K. Oksman2
1Applied Wood Materials Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
2Division of Materials Science, Luleå University of Technology, Luleå, Sweden

Tóm tắt

Bionanocomposites of poly(lactic acid) (PLA) and chemically modified, nanofibrillated cellulose (NFC) powders were prepared by extrusion, followed by injection molding. The chemically modified NFC powders were prepared by carboxymethylation and mechanical disintegration of refined, bleached beech pulp (c-NFC), and subsequent esterification with 1-hexanol (c-NFC-hex). A solvent mix was then prepared by precipitating a suspension of c-NFC-hex and acetone-dissolved PLA in ice-cold isopropanol (c-NFC-hexsm), extruded with PLA into pellets at different polymer/fiber ratios, and finally injection molded. Dynamic mechanical analysis and tensile tests were performed to study the reinforcing potential of dried and chemically modified NFC powders for PLA composite applications. The results showed a faint increase in modulus of elasticity of 10 % for composites with a loading of 7.5 % w/w of fibrils, irrespective of the type of chemically modified NFC powder. The increase in stiffness was accompanied by a slight decrease in tensile strength for all samples, as compared with neat PLA. The viscoelastic properties of the composites were essentially identical to neat PLA. The absence of a clear reinforcement of the polymer matrix was attributed to poor interactions with PLA and insufficient dispersion of the chemically modified NFC powders in the composite, as observed from scanning electron microscope images. Further explanation was found in the decrease of the thermal stability and crystallinity of the cellulose upon carboxymethylation.

Tài liệu tham khảo

Auras R, Harte B, Selke S (2004) Macromol Biosci 4:835–864 Garlotta D (2001) J Polym Environ 9:63–84 Siro I, Plackett D (2010) Cellulose 17:459–494 Samir M, Alloin F, Dufresne A (2005) Biomacromolecules 6:612–626 Chazeau L et al (1999) J Appl Polym Sci 71:1797–1808 Favier V, Chanzy H, Cavaille JY (1995) Macromolecules 28:6365–6367 Marchessault RH, Morehead FF, Walter NM (1959) Nature 184:632–633 Turbak AF, Snyder FW, Sandberg KR (1983) J Appl Polym Sci Symp 37:815–827 Oksman K et al (2006) Compos Sci Technol 66:2776–2784 Mathew AP et al (2006) In: Oksman K, Sain M (eds) Cellulose nanocomposites: processing, characterization, and properties. American Chemical Society, Washington, pp 114–131 Petersson L, Kvien I, Oksman K (2007) Compos Sci Technol 67:2535–2544 Bondeson D, Oksman K (2007) Compos A Appl Sci Manuf 38:2486–2492 Bondeson D, Oksman K (2007) Compos Interfaces 14:617–630 Iwatake A, Nogi M, Yano H (2008) Compos Sci Technol 68:2103–2106 Suryanegara L, Nakagaito AN, Yano H (2009) Compos Sci Technol 69:1187–1192 Tingaut P, Zimmermann T, Lopez-Suevos F (2010) Biomacromolecules 11:454–464 Jonoobi M et al (2010) Compos Sci Technol 70:1742–1747 Eyholzer C et al (2010) Cellulose 17:19–30 Lee K-Y, Blaker JJ, Bismarck A (2009) Compos Sci Technol 69:2724–2733 Fukuzumi H et al (2009) Biomacromolecules 10:162–165 Leza ML et al (1989) Die Angewandte Makromolekulare Chemie 168:195–203 Rosenau T et al (2003) Polymer 44:6153–6158