Cardanol–formaldehyde thermoset resin was reinforced with raw and chemically modified fibers of bamboo (Bambusoideae). Modified fibers were treated with alkali solutions of NaOH (5% and 10%) and bleached with sodium hypochlorite NaClO/H2O (1:1) at 60℃–75℃. The biocomposites were fabricated with a hand lay-up technique. This study investigated the fibers microstructure before and after alkali treatment, as the interaction between matrix and reinforce by scanning electron microscopy. The Fourier transform infrared spectra allowed the identification of characteristic stretching frequencies attributed to the methyl groups of lignin. A considerable increase in thermal stability was observed in the materials studied, which was verified by thermogravimetric analysis and confirmed by X-ray diffraction. The tensile tests showed that the mechanical properties (tensile modulus, tensile strength, and elongation at break) of bamboo fibers improved after alkali treatment, as well as the increase in the biodegradation in simulated soil, showing that the alkaline treatment acted removing the macro components of the fibers (lignin and hemicellose), making them more susceptible to the action of microorganisms.
BarretoACHEsmeraldoMARosaDS. Cardanol composites reinforced with jute fiber: microstructure, biodegradability and mechanical properties. Polym Compos2010; 31: 1928–1937.
2.
MafezzoliACalòEZurloS. Cardanol based matrix composites reinforced with natural fibres. Compos Sci Technol2004; 64: 839–845.
3.
JosephKThomasSPavithranC. Effect of chemical treatment on the tensile properties of short sisal fibre-reinforced polyethylene composites. Polymer1996; 37: 5139–5149.
4.
NayakSKMohantySSamalSK. Influence of short bamboo/glass fiber on the thermal, dynamic mechanical and rheological properties of polypropylene hybrid composites. Mater Sci Eng A2009; 523: 32–38.
5.
KaliaSKaithBSKaurI. Pretreatments of natural fibers and their application as reinforcing material in polymer composites – a review. Polym Eng Sci2009; 49: 1253–1272.
6.
BarretoACHRosaDSFechinePBA. Properties of sisal fibers treated by alkali solution and their application into cardanol-based composites. Compos A2011; 42: 492–500.
7.
RosaMFChiouBSMedeirosES. Effect of fiber treatments on tensile and thermal properties of starch/ethylene vinyl alcohol copolymers/coir composites. Bioresour Technol2009; 100: 5196–5202.
ScurlockJMODaytonDCHamesB. Bamboo: an overlooked biomass resource. Biomass Bioenergy2000; 19: 229–235.
10.
LiSHZengQYXiaoYL. Biomimicry of bamboo bast fiber with engineering biocomposite materials. Mater Sci Eng1995; 3: 125–130.
11.
HanGLeiYWuQ. Bamboo–fiber filled high density polyethylene composites: effect of coupling treatment and nanoclay. J Polym Environ2008; 16: 123–130.
12.
ShinFGYippMW. Analysis of the mechanical propertiesand microstructure of bamboo-epoxy composites. J Mater Sci1989; 24: 3483–3490.
13.
SwamyRN. Natural fibre reinforced cement and concrete, concrete technology and design, 5th ed. London: Blackie and Son Glasgow, 1888.
14.
DasMChakrabortyD. Processing of the unidirectional powdered phenolic resin-bamboo fiber composites and resulting dynamic mechanical properties. J Reinf Plast Compos2009; 28: 1339–1348.
15.
LomonacoDMaiaFJNMazzettoSE. Thermal evaluation of cashew nutshell liquid as new bioadditives for poly(methyl methacrylate). J Therm Anal Calorim2013; 111: 619–626.
16.
SegalLCreelyLMartinAE. An empirical method for estimating the degree of crystallinity of native cellulose using X-ray diffractometer. Text Res J1959; 29: 786–794.
DasMChakrabortyD. Effects of alkalization and fiber loading on the mechanical properties and morphology of bamboo fiber composites. II. Resol matrix. J Appl Polym Sci2009; 112: 447–453.
19.
AlvarezVAVázquezA. Thermal degradation of cellulose derivatives/starch blends and sisal fibre composites. Polym Degrad Stabil2004; 84: 13–21.
20.
RoutJTripathySSNayakSK. Scanning electron microscopy study of chemically modified coir fibers. J Appl Polym Sci2000; 79: 1169–1177.
21.
GeethammaVG. Biocomposite of short coir fibres and natural rubber: effect of chemical modification, loading and orientation of fibre. Polymer1998; 39: 1483–1497.
22.
ReddyaNYangY. Structure and properties of high quality natural cellulose fibers from cornstalks. Polymer2005; 46: 5494–5500.
23.
MegiattoJrJDSilvaCGRosaDS. Sisal chemically modified with lignins: correlation between fibers and phenolic composites properties. Polym Degrad Stabil2008; 93: 1109–1121.
24.
HullD. An introduction to composites materials, New York: University Press, 1981, pp. 37–42.
25.
WangQFanXGaoW. Characterization of bioscoured cotton fabrics using FT-IR ATR spectroscopy and microscopy techniques. Carbohydr Res2006; 341: 2170–2175.
26.
PendeyKKPitmanAJ. Examination of the lignin content in a softwood and a hardwood decayed by a brown-rot fungus with the Acetyl Bromide Method and Fourier Transform Infrared Spectroscopy. J Polym Sci Part A: Polym Chem2004; 42: 2340–2346.
27.
SgricciaNHawleyMCMisraM. Characterization of natural fiber surfaces and natural fiber composites. Compos A2008; 39: 1632–1637.
28.
Paiva JMF. Compósitos de Matrizes Termorrígidas Fenólicas e Lignocelulólicas Reforçadas com Fibra Vegetais. PhD thesis, Instituto de Química de São Carlos, Universidade de São Paulo, São Paulo, Brazil, 2001.
29.
LiuYHuH. X-ray diffraction study of bamboo fibers treated with NaOH. Fiber Polym2008; 9: 735–739.
30.
GomesAMatsuoTGodaK. Development and effect of alkali treatment on tensile properties of curaua fiber green composites. Compos A2007; 38: 1811–1820.
31.
GassanJBledzkiAK. Possibilities of improving the mechanical properties of jute/epoxy composites by alkali treatment of fibres. Compos Sci Technol1999; 59: 1303–1309.
32.
SzcześniakLRachockiATritt-GocJ. Glass transition temperature and thermal decomposition of cellulose powder. Cellulose2008; 15: 445–451.
33.
YangHYanRChenH. Characteristic of hemicellulose, cellulose and lignin pyrolysis. Fuel2007; 86: 1781–1788.
34.
MaheswariCUReddyKORajuluAV. Tensile properties and thermal degradation parameters of tamarind fruit fibers. J Reinf Plast Compos2008; 27: 1827–1832.
35.
LiuYHuH. X-ray Diffraction study of bamboo fibers treated with NaOH. Fiber Polym2008; 9: 735–739.
36.
SreekumarPAThomasSPSaiterJM. Effect of fiber surface modification on the mechanical and water absorption characteristics of sisal/polyester composites fabricated by resin transfer molding. Compos A2009; 40: 1777–1784.
37.
Barreto ACH, Junior AEC, Freitas JEB, et al. Biocomposites from dwarf-green Brazilian coconut impregnated with cashew nut shell liquid resin. J Compos Mater 2013; 47(4): 459–466.
