Tratamiento de pulpas para su aplicación en materiales cementícios. Holmer Savastano Junior FZEA USP Brasil

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1 Tratamiento de pulpas para su aplicación en materiales cementícios Holmer Savastano Junior FZEA USP Brasil

2 Preparación de la pulpa celulosica

3 Algunos tipos de tratamientos Modificação mecânica das fibras celulósicas (refino / fibrilação das fibras) Branqueamento das fibras celulósicas Modificação por configurações de micelas Modificação superficial com silanos Modificação superficial com isocianatos Modificações com ácidos e anidridos

4 Ensaio de flotacão - Fibras modificadas com n-octadecil-isocianato

5 Modificação por descargas elétricas e técnicas de irradiação Descargas tipo corona, descargas de plasma e, mais recentemente, laser, raios-gama e irradiação ultra-violeta (UV) em vácuo Modificação via polimerização por abertura de anéis Oxipropilação parcial das fibras celulósicas

6 Modificação via deposição de nanopartículas inorgânicas/poliméricas Uso de nanocristais semi-condutores de sulfeto de cádmio (CdS) e nanopartículas catiônicas poliméricas na superfície de fibras celulósicas para torná-las fotoluminescentes; Precipitação de nanopartículas de dióxido de titânio na superfície de fibras para melhorar as propriedades ópticas da celulose

7 Cement based composites - Problem addressed The need for low cost fiber-cement with acceptable performance under aggressive climates (durability of the products). Availability of the raw-materials commonly used in the manufacture of the asbestos-free fiber-cement. Demand for alternative raw-materials, as appropriate fibers and binders and inert fillers, to substitute traditional ones (high cost and large consumption of energy).

8 Short x long pulp fibers

9 Eucalyptus x Pine pulp Eucalyptus pulp fibres 0.83 ± 0.01 mm Pinus pulp 2.40 ± 0.09 mm less heterogeneous in length Short fibres Higher number of fibres per volume or weight Fraction (%) Eucalyptus pulp Pinus pulp Length ranges (mm) The smaller the fibre length, the easier the fibre dispersion Effect on flocullation Number fibres (10 6 /g) Eucalyptus increasing refining Median chord size (m) Pinus

10 Results BSEI SEM Eucalyptus The short Eucalyptus better distributed The higher number of bridging fibers Pinus Increasing MOR and toughness of the composite.

11 Summary of different treatments to the fibres Bleaching

12 Bleaching Effect of pulp bleaching Bleaching extract the fibre components (lignin and extractives from fibre cell wall). Eucalyptus unbleached Eucalyptus bleached 1 m 1 m

13 Mechanical results days (MPa) (MPa) Eucalyptus unbleached Eucalyptus bleached Pinus unbleached Pinus bleached (mm/mm) (mm/mm) Eucalyptus unbleached Eucalyptus bleached Pinus unbleached Pinus bleached 200 cycles After 28 days of cure Cement composite with Pinus pulp higher mechanical performance After 200 accelerated ageing cycles Cement composite with Eucalyptus pulp significantly higher mechanical performance

Eucalyptus unbleached c 2 Toughness (kj/m ) MOR (MPa) Decrease

14 Mineralization of the fibre Eucalyptus bleached Extensive fibre mineralization a 28 days 200 cycles 8 Eucalyptus unbleached c 2 Toughness (kj/m ) MOR (MPa) Decrease in mechanical properties after accelerated ageing days 200 cycles

15 Alkali treatment dissolves hemicellulose and lignin by hydrolyzing acetic acid esters and by swelling cellulose Acid treatment The lignin in hardwood species is partly dissolved by sulfuric acid during the acid hydrolysis

16 Pyrolysis treatments The pyrolysis of lignin occurs in inert atmospheres at high temperatures The thermal decomposition of the lignin is also affected by the acid pretreatment

17 Refining

18 Fiber microstructure Original sliver Bunch of individual fibres Individual filaments

The fibrillar surface structures of the Eucalyptus fibres higher roughness (RMS = 74 ± 18

19 Results - AFM Eucalyptus fibres: more fibrillar structure. Pinus fibres: the typical surface structure was granular. The fibrillar surface structures of the Eucalyptus fibres higher roughness (RMS = 74 ± 18 nm) than Pinus fibres (RMS = 52 ± 10 nm). Eucalyptus Indicative of the higher potential of the Eucalyptus fibres to anchorage in the cement matrix. Pinus

20 Solids retention (%) Pulp freeness (CSF ml) Eucalyptus Pinus increasing refining b 0 increasing refining c Drainage rate (g/s) Water retention (%) Drainage Parameters Higher number of fibres did not prejudice the drainage rate of the fibre-cement suspensions. Significant improvement of the solids retention during the dewatering of the suspension (18 mesh = 0.9 mm). Possible to improve the solids retention of the Pinus pulp increasing the refining.

21 Refining days 10 Effect of refining Increase in fibre-matrix anchorage after 28 days of cure; Decay in toughness after accelerated ageing. (MPa) Euc unbleached (unrefined) Euc unbleached (CSF 250 ml) (mm/mm) 200 cycles 10 (MPa) Euc unbleached (unrefined) Euc unbleached (CSF 250 ml) (mm/mm)

22 Surface treatments

Modified Fibre treatment Unmodified Condition Modified TE (kj/m2) 6.9 ± 1.1 9.9 ± 1.4 0.86 ± 0.25 6.5 ± 1.

23 Surface treatments Unmodified Effect of surface modification of the pulp fibres with silanes Decrease mineralization of fibers Small improvement in the mechanical properties. Modified Fibre treatment Unmodified Condition Modified TE (kj/m2) 6.9 ± ± ± ± ± ± ± ± ± ± 0.12 LOP (MPa) 28 days Modified Unmodified MOR (MPa) 200 cycles 6.3 ± ± 0.9

24 Fibras após modificação com metacriloxipropiltri-metoxisilano (MPTS) e aminopropiltri-etoxisilano (APTS)

25 Tratamento das macrofibras vegetais Propriedades das fibras vegetais Tipos de tratamento Alterações nas caraterísticas das fibras

26 Nature of the fiber Chemical composition (%) [ ± Cumulative standard deviation] Elemental composition (%) Moisture Lignin Cellulose Hemicellulose Extractives C O H N Ash Coconut coir [±0.05] [±1.73] [±1.44] [±2.34] 8.77 [±0.39] [±0.03] [±0.03] 5.44 [±0.03] 0.36 [±0.002] 1.05 [±0.05] Coconut sheath 5.90 [±1.84] 29.7 [±4.36] [±2.88] [±3.46] 1.74 [±0.71] [±0.21] [±0.23] 5.69 [±0.03] 0.44 [±0.002] 8.39 [±0.03] Bagasse * 45.1* 6.3* ** 3.5* [±1.60] [±2.26] [±2.41] [±2.52] [±0.74] ** ** ** ** ** Banana trunk (Guad.) 9.74 [±1.42] [±0.66] [±3.61] [±2.03] 4.46 [±0.11] [±0.18] [±0.22] 5.19 [±0.02] 0.93 [±0.005] 8.65 [±0.03] Banana trunk (Brazil) ** ** ** ** ** ** ** Banana leaf [±0.03] [±1.32] [±1.42] [±1.11] 9.84 [±0.11] [±0.22] [±0.19] 6.10 [±0.03] 1.36 [±0.007] 7.02 [±0.03] Arrow Root D ** ** ** ** ** Arrow Root D ** ** ** ** ** Sisal ** ** ** ** ** ** ** Softwood ** ** ** ** ** ** **

27 Fiber Untreated fiber dimensions [st. dev.] Aspect ratio L/w Length Untreated Pyrolysis Acid Alkaline Silane Width (µm) Thickness (µm) (mm) Arrow Root (D1) nd nd nd [±3.35] [±86.14] [±38.6] Arrow Root (D2) 5.45 [±2.01] Bagasse (B) 3.69 Banana Trunk (BT) Banana Leaf (BL) Coconut Coir (CC1) Coconut Coir (CC2) Coconut Sheath (CT) ±2.15] 1.9 [±0.64] 1.70 [±0.91] [±8.17] 2.7 [±2.46] 5.47 [±3.08] [±46.98] [±329.4] [±264.49] [±245.94] [±198.72] [±279.42] ±258.23] [±29.61] [±90.75] [±86.94] [±55.26] [±150.94] 215 [±98.67] [±134.76] nd nd nd 6, ,3-12, nd nd nd nd nd nd nd nd Nd nd nd Nd nd

29 SEM images of pyrolyzed banana Banana leaf fiber left x 200 right x 5000 fibers Banana trunk fiber left x 200 right x 5000

30 Tensile strength of treated and untreated fibers Bagasse Banana trunk Tensile Strength (MPa) Acidic treatment Basic treatment Pyrolysis No treatment Treatment of the Fibers

31 Scanning electron micrography of bagasse fibers a) Unpyrolyzed fiber b) Pyrolyzed fiber c) Unpyrolyzed fiber treated with silane S1 d) Pyrolyzed fiber treated with silane S1 e) Unpyrolyzed fiber treated with silane S2 f) Pyrolyzed fiber treated with silane S2

32 Comentários adicionais Importância do preparo da fibra. Destaque para o tratamento de branqueamento x não branqueamento no caso do Eucalipto. Importância do refino para o processo no caso da fibra de Pinus. Interesse no processo de pirólise em atmosfera inerte.

33 Lectura complementar G.H.D. Tonoli, H. Savastano Jr., E. Fuente, C. Negro, A. Blanco, F.A. Rocco Lahr. Eucalyptus pulp fibres as alternative reinforcement to engineered cement-based composites. Industrial Crops and Products, 31 (2010) G.H.D. Tonoli, U.P. Rodrigues Filho, H. Savastano Jr., J. Bras, M.N. Belgacem, F.A. Rocco Lahr. Cellulose modified fibres in cement based composites. Composites: Part A 40 (2009) M.-A. Arsène, K. Bilba, H. Savastano Jr., K. Ghavami. Treatments of non-wood plant fibers used as reinforcement in composite materials. In preparation.

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