IMPACT OF MICRO/NANOFIBRILLATED CELLULOSE PREPARATION ON THE REINFORCEMENT PROPERTIES OF PAPER AND COMPOSITES FILMS. Denilson DA SILVA PEREZ a, * Sandra TAPIN-LINGUA a , Anne LAVALETTE a,c , Thiago BARBOSA a,c,d , Israel GONZALEZ b , Gilberto SIQUEIRA b , Julien BRAS b , Alain DUFRESNE b . a) Institut Technologique FCBA, New Materials Division, Grenoble, France. b) INP Grenoble PAGORA, Grenoble, France. c) ESB - Ecole Supérieure du Bois, Nantes, France. d) UFPR - Universidade Federal do Parana, Curitiba, Brazil. * E-mail : [email protected]Introduction Micro- and nano-fibrillated cellulose (M/NFC) seem to be one of the ways of better exploiting the potential of cellulosic fibres than the usual paper-based application (1-6). Depending on the fibrous raw materials, pre-treatment and fibrillation conditions, different types of micro/nanofibrillated cellulose can be obtained in terms of microfibrilles individualisation, dimensions, crystallinity, etc. Moreover, the chemical modification of micro- and nano-fibres surfaces can not only impart different functionalities but also be used as pre-treatment for their production. In particular TEMPO-mediated oxidation allow selectively creating carboxyl groups on C6 carbon of cellulosic fibres, which can be used for further grafting of specific moieties either by amidation or esterification (5-8). The work described here aims at understanding the impact of M/NFC preparation on the properties of these materials and consequently on their reinforcement capabilities for paper and composites applications. Materials and Methods Bleached kraft pulps from hardwoods or softwoods were used as raw materials for the production of M/NFC. The pulps were firstly highly refined then enzymatically treated (Celluclast-Novozymes, 5% pulp consistency, 10 mL enzyme for 100 g–dry pulp, 50°C, 2 hours.). Different M/NFC grades were produced by homogenization using laboratory-scale equipment Microfluidizer M110EH at 2 % concentration equipped with different interaction chambers (Z-shaped, internal diameter of 100, 200, and 400 μm) allowoing microfibrils individualisation by high pressure shearing (up to 2200 bars) of the cellulosic suspensions. Three contrasted types of M/NFC were produced and used as reinforcement agents for paper and latex composites films. Moreover, these M/NFC were chemically modified in surface by TEMPO-oxidation and amidation of the carboxyl groups to graft polyethyleneglycol (PEG) or aromatic groups based on the protocol of the work described earlier for fibres (9). Results and discussions 1) M/NFC preparation Different optical and electronic microscopy devices were used to follow the conversion of pulp fibres into nanofibrillated cellulose (Figure 1). Figure 1 – A :Light micrographyexamination of MFC obtained using 400 μm chamber; B : SEM examination of M/NFC obtained using 200 μm chamber; C : TEM examination of NFC obtained using 100 μm chamber. The cellulosic material obtained after 3 passes in 400 μm chamber is essentially composed of short cut fibres and some microfibrils (MFC). After 5 passes in a 200 μm chamber NFC is obtained, but important non-destructured material is still present. Finally, 5 passes in a 100 μm chamber allow obtaining a homogenous material constituted essentially of cellulose nanofibres. A B A C
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IMPACT OF MICRO/NANOFIBRILLATED CELLULOSE PREPARATION ON THE REINFORCEMENT PROPERTIES OF PAPER AND COMPOSITES FILMS.
Denilson DA SILVA PEREZa,* Sandra TAPIN-LINGUAa, Anne LAVALETTE a,c, Thiago BARBOSAa,c,d, Israel GONZALEZb, Gilberto SIQUEIRAb, Julien BRASb, Alain DUFRESNEb. a) Institut Technologique FCBA, New Materials Division, Grenoble, France. b) INP Grenoble PAGORA, Grenoble, France. c) ESB - Ecole Supérieure du Bois, Nantes, France. d) UFPR - Universidade Federal do Parana, Curitiba, Brazil. * E-mail : [email protected]
Introduction Micro- and nano-fibrillated cellulose (M/NFC) seem to be one of the ways of better exploiting the potential of cellulosic fibres than the usual paper-based application (1-6). Depending on the fibrous raw materials, pre-treatment and fibrillation conditions, different types of micro/nanofibrillated cellulose can be obtained in terms of microfibrilles individualisation, dimensions, crystallinity, etc. Moreover, the chemical modification of micro- and nano-fibres surfaces can not only impart different functionalities but also be used as pre-treatment for their production. In particular TEMPO-mediated oxidation allow selectively creating carboxyl groups on C6 carbon of cellulosic fibres, which can be used for further grafting of specific moieties either by amidation or esterification (5-8). The work described here aims at understanding the impact of M/NFC preparation on the properties of these materials and consequently on their reinforcement capabilities for paper and composites applications.
Materials and Methods Bleached kraft pulps from hardwoods or softwoods were used as raw materials for the production of M/NFC. The pulps were firstly highly refined then enzymatically treated (Celluclast-Novozymes, 5% pulp consistency, 10 mL enzyme for 100 g–dry pulp, 50°C, 2 hours.). Different M/NFC grades were produced by homogenization using laboratory-scale equipment Microfluidizer M110EH at 2 % concentration equipped with different interaction chambers (Z-shaped, internal diameter of 100, 200, and 400 µm) allowoing microfibrils individualisation by high pressure shearing (up to 2200 bars) of the cellulosic suspensions. Three contrasted types of M/NFC were produced and used as reinforcement agents for paper and latex composites films. Moreover, these M/NFC were chemically modified in surface by TEMPO-oxidation and amidation of the carboxyl groups to graft polyethyleneglycol (PEG) or aromatic groups based on the protocol of the work described earlier for fibres (9).
Results and discussions
1) M/NFC preparation Different optical and electronic microscopy devices were used to follow the conversion of pulp fibres into nanofibrillated cellulose (Figure 1).
Figure 1 – A :Light micrographyexamination of MFC obtained using 400 µm chamber; B : SEM examination of M/NFC obtained using 200 µm chamber; C : TEM examination of NFC obtained using 100 µm chamber.
The cellulosic material obtained after 3 passes in 400 µm chamber is essentially composed of short cut fibres and some microfibrils (MFC). After 5 passes in a 200 µm chamber NFC is obtained, but important non-destructured material is still present. Finally, 5 passes in a 100 µm chamber allow obtaining a homogenous material constituted essentially of cellulose nanofibres.
A B
A
C
2) Paper reinforcement The different M/NFC were applied as reinforcement agent at 1, 5 and 20 % in weight on refined hardwoods and softwoods pulps aiming at improving the physical properties (bulk and tensile, tear, burst indexes). Figure 2 clearly demonstrates that the smaller and more homogeneous the M/NFC, the higher the reinforcement effects. Thus, the addition of 20 % of M/NFC produced after 5 passes on 100 µm chamber allows improving simultaneously the tensile and tear indexes higher than 90 %. For the M/NFC produced using 400 µm and 200 µm chambers which are less homogenous, the improvements are respectively 38 % and 56 % for the tensile index and 37 % and 80 % for the tear index. TEMPO-oxidation of M/NFC allows further gains in physical properties (+ 10-25 %).
Figure 2: Effect of the addition of hardwood and softwood MFC on the pulp mechanical properties (HW-R-26:
hardwood bleach Kraft pulp refined at 26 °SR; SW-R-25: softwood bleach Kraft pulp refined at 25 °SR / SW_100-5: MFC from softwood pulps; HW_100-5: MFC from hardwood pulps)
3) Composites films An important reinforcement was obtained when using M/NFC (Table 1). At 3 % of M/NFC, the Young’s modulus compared to latex is multiplied by 6 and the tensile strength is by 2. At 12 % of non-modified M/NFC, the Young’s modulus can reach 60-fold the latex one. If TEMPO-oxidized M/NFC are used, values up to 100-fold the modulus of latex were obtained, while the tensile strength is multiplied by 12. Moreover, these composites films preserve certain elasticity, measured by the strain at break values, contrarily to the non-modified M/NFC. Finally, the grafting of PEG or aromatic chains by amidation generated films with high tensile strength and strain at break, but considerably lower Young’s modulus.
Table 1 – Mechanical properties of composites films reinforced with different MFC/NFC. Type and characteristics of the reinforcement E (MPa) ƐR (%) δR (MPa)
Latex alone 0.77 409 0.65
(3%) 4.47±2.05 230±88.05 1.18±0.2 Natural
(12%) 47.64±5.25 76±15.55 2.35±0.04
(3%) 5.32±0.49 307±50.91 1.75±0.25 TEMPO Oxidised (12%) 75.75±19.61 191±62.93 7.82±0.53
Acknowledgments The authors thank ADEME (contract AGRICE 06.01C.0039)/CTPi members for the financial support. References 1) Herrick FW et al. (1983). J Appl Polym Sci: Appl Polym Symp 37:797-813. 2) Turbak AF et al. (1983). J Appl Polym Sci: Appl Polym Symp 37:815 - 827. 3) Henriksson M. et al. (2007). Europ Polym J 43:3434-3441. 4) Paakko M. et al. (2007). Biomacromolecules 8:1934-1941. 5) Saito T. et al. (2006). Biomacromolecules 7:1687-1691. 6) Saito T. et al (2007). Biomacromolecules 8:2485-2491. 7) da Silva Perez, D. et al. (2003) Biomacromolecules, 4, 1417-1425 (2003).
9) da Silva Perez, D. Guillemain, A., Petit-Conil, M., Strategies for surface fibre functionalisation using TEMPO-mediated oxydation. 11th European Workshop on Lignocellulosics and Pulps, Hamburg, Germany (2010) Proceedings, pp 377-380.
Impact of micro/nanofibrillated cellulose preparation on the reinforcement
properties of paper and composites films
Sandra Tapin-Lingua, Denilson Da Silva Perez
Tappi Nano2010 - 28/09/2010 - STL - 2
• Chemical pre-treatmentsControlled acid hydrolysis Alkaline swelling and/or
• MFC ProductionDevelopment of a M/NFC production protocolCharacterisation of M/NFC
• M/NFC induced properties on pulp strengthMechanical properties: x 2 with NFC additionImpact of NFC characteristics on pulp properties the smaller and more homogenous give the best results
• M/NFC induced properties on composites filmsMechanical properties
Young modulus:» x 62 with 12 % NFC »x 98 with 12 % Oxidized NFC
Tensile strength:» x 12 with 12 % oxidized NFC
Oxidation of fibres/MFC improves the strength properties of composites
Tappi Nano2010 - 28/09/2010 - STL - 17
ACKNOWLEDGEMENTS
Co-autors: Anne Lavalette, Thiago Brabosa, IsraelGonzalez, Gilberto Siqueira, Julien Bras and Alain Dufresne
Partial financial support from French energy agency-ADEME