Mariatti et al. (2008) proposed the utilization of reinforcing part of unsaturated polyester (USP) resin for more opportunities in the waste management sector. To
Composites from Bagasse Fibers, Its Characterization and Applications 97
modify the fiber properties, chemical treatments processes were carried out by using NaOH and acrylic acid. The result showed that by, selecting different fiber weights, acrylic-acid-treated fiber composites demonstrated improved mechanical characteristics than sodium-hydroxide-treated fiber composites. Dynamic mechani- cal analysis (DMA) shows that the treatment of fibers by sodium-hydroxide- and acrylic-acid-reinforced composites improves the storage properties of composites; however, from water absorption study, it has been found that processed fiber com- posites are better in terms of “lower water absorption properties” than unprocessed fiber composites.
From study, it has been found that on the one hand surface modification of ba- gasse decreases the moisture absorption, and on the other hand it improves the damp ability and hence ultimately improves the mechanical characteristics of composites.
The tensile and flexural properties of the composites, as shown in Figs. 6 and 7, represent the response of treated and untreated bagasse content. It has been found that the most favorable value of treated bagasse fiber for improving the tensile and flexural strength of the polyester composites is from 10 to 20 % (v/v). The increase in mechanical properties of sodium-hydroxide- and acrylic-acid-treated bagasse- based composites is due to increase in fiber surface adhesives characteristics by the fibrillation process as mentioned by Mariatti et al. (2008).
De Sousa et al. (2004) have mentioned the effect of three operating parameters on the mechanical properties of chopped bagasse–polyester-based composites. From the analysis, it has been found that composites made from bagasse with size under mesh #20 sieve pretreated for sugar and alcohol extraction were optimum and have the best mechanical characteristics. This is due to the fact that treatment increases the surface area and the complete sterilization of the bagasse surface. The molding pressure made a closer contact between the bagasse and the resin matrix, which condenses the snare voids. The weight fractions of the chopped bagasse are shown in Table 1. Sieving provides a very uniform size distribution of particulate
D. Verma et al. 98
Table 1 Weight factions of the chopped bagasse. (Reproduced with permission from Elsevier Ltd.
(Sousa et al. 2004))
Sieve (mesh) Size of retained material (mm) Weight fraction (%)
4 > 4.7 0.6
10 4.7–2.0 31.7
20 2.0–0.85 35.8
Bottom < 0.85 31.9
Fig. 7 a Flexural strength and b flexural modulus of treated and untreated fiber composites at dif-
ferent fiber loadings. (Reproduced with permission from Elsevier (Mariatti et al. 2008))
Fig. 6 The a tensile strength and b tensile modulus of treated and untreated fiber composites at
different fiber loadings. Unfilled polyester resin is used as a control. (Reproduced with permission from Elsevier (Mariatti et al. 2008))
Composites from Bagasse Fibers, Its Characterization and Applications 99
material ranging from 4.7 to under 0.85 mm. Three different meshes were used in the present investigation to analyze the effect of the size of bagasse on the mechanical properties of the composites. Table 2 shows the flexural stress ( σr) and the deformation at rupture ( ε) of the composites.
Balakrishna et al. (2013) prepared and tested Asian palmyra which is a natural fiber-reinforced composites (NFRC). The experiments were designed in accordance with a factorial design (three level) and determined the deviation of tensile strength of short and randomly oriented NFRC under the condition of control parameters. A thriving mixture of process parameters showed an improvement in the mechani- cal characteristics of the composite. The developed model was able to explain the influence of a design alter on each one of the operating parameters. Response surface methodology (RSM) is used in this study to model the influence of operat- ing parameter on tensile strength. The mathematical model which is developed to predict tensile strength is found statistically suitable within the operating range of the designed parameters.
Tables 3, 4, and 5 show distinctive experiment values of tensile strength (related to output responses) and are used to put into practice the proposed tactic. The developed mathematical relationships are used to develop a correlation for tensile strength with the range of process parameters which will ultimately result in the
Table 2 Flexural properties as a function of the bagasse size. Untreated bagasse. Molding pres-
sure: 0.3 MPa. (Reproduced with permission from Elsevier Ltd. (Sousa et al. 2004)) Sieve (mesh) σr (MPa) εr (%)
10 7.6 ± 1.4 1.60 ± 0.14
20 19.5 ± 1.1 1.65 ± 0.10
Bottom 21.6 ± 1.6 1.84 ± 0.14
Table 3 Mechanical properties of the composite of fiber length 3 mm. (Reproduced with permis-
sion from Elsevier Ltd. (Balakrishna et al. 2013)) Specimen ID Percent of
fiber Alkali treat-ment time (2, 4, 6 h) Tensile load (N) Tensile strength (MPa) Elongation (%) Sp301 20 2 549.653 13.741 2.51 Sp302 30 2 631.846 15.796 6.66 Sp303 40 2 674.846 16.857 4.78 Sp304 20 4 594.653 14.866 10.47 Sp305 30 4 658.076 16.451 3.57 Sp306 40 4 687.493 17.187 6.09 Sp307 20 6 696.653 17.416 2.42 Sp308 30 6 727.134 18.178 5.32 Sp309 40 6 789.652 19.742 4.27
D. Verma et al. 100
optimization of the operating parameters. For the computation of the regression coefficients, design expert 8.0 as statistical analysis software is used. The interac- tion effects between the process parameters and tensile strength was also found suitable, and based on analysis and results, a second-order quadratic mathematical model is suggested.
Choudhury et al. (2011) prepared epoxy novolac hybrid composites reinforced with the help of short bagasse and coir fibers. The dynamic mechanical properties and the mechanical properties of the composite were determined and reported for different layering patterns of the composites. It is found that the tensile strength of the three-layer composites is maximum as compared to the two-layer composites; on the other hand, it is observed that the flexural performance of the three-layer composites is lesser as compared to two-layer composites. The tensile strength of
Table 4 Mechanical properties of the composite of fiber length 5 mm. (Reproduced with permis-
sion from Elsevier Ltd. (Balakrishna et al. 2013)) Specimen ID Percent of
fiber Alkali treatment time (2, 4, 6 h) Tensile load (N) Tensile strength (MPa) Elongation (%) Sp501 20 2 824.519 20.612 4.06 Sp502 30 2 766.615 19.165 12.17 Sp503 40 2 819.980 20.499 15.89 Sp504 20 4 834.134 20.853 5.35 Sp505 30 4 799.210 19.980 3.27 Sp506 40 4 846.346 21.158 6.42 Sp507 20 6 823.442 20.585 9.56 Sp508 30 6 864.115 21.602 13.79 Sp509 40 6 891.846 22.296 8.60
Table 5 Mechanical properties of the composite of fiber length 7 mm. (Reproduced with permis-
sion from Elsevier Ltd. (Balakrishna et al. 2013)) Specimen ID Percent of
fiber Alkali treatment time (2, 4, 6 h) Tensile load (N) Tensile strength (MPa) Elongation (%) Sp701 20 2 864.423 19.116 2.50 Sp702 30 2 864.136 21.604 4.65 Sp703 40 2 875.961 21.899 1.84 Sp704 20 4 869.346 21.733 17.37 Sp705 30 4 898.856 22.471 19.40 Sp706 40 4 926.960 23.174 11.45 Sp707 20 6 910.653 22.766 3.70 Sp708 30 6 920.340 23.008 3.24 Sp709 40 6 1091.34 27.283 10.23
Composites from Bagasse Fibers, Its Characterization and Applications 101
the mixed composite is similar to that of three-layer composites having bagasse as covering material. The temperature and frequency functions were used to study the effect of different pattern of layers on damping behavior (tan δ), storage modulus ( E′), and loss modulus ( E″). It is found that the modulus value of the two layers composite is lesser than that of three layers as bagasse–coir–bagasse com- posites. The composite made with the coir as covering layer shows minimum E′. The two-layer composite shows the best damping property. The theoretical model- ing represents a suitable relation with experimental outputs above glass transition temperature ( Tg) while the theoretical model departs experimental data at lesser
Tg. The activation energy of the glass transition was calculated by Arrhenius correlation.
Choudhury et al. (2011) also reported and found diameter of fiber (bagasse based) to be higher as compared to coir fiber. The tensile characteristics of various sheeting orders of hybrid composites consisting of three-layer/sheets, two-layer, and mix composites are reported in Fig. 8a, b. It has been noticed that the tensile strength was maximum when bagasse was used as the covering material and coir as the core material. This is due to the fact that the use of high-strength material
Fig. 8 Comparison of mechanical properties of different layering pattern hybrid composites.
D. Verma et al. 102
which is the prime load-bearing component for tensile value computation. In other composites of coir–bagasse–coir, the value is minutely lesser because of the low- strength coir fiber. In the bilayer, the tensile strength is found to be again lesser. The tensile modulus for the trilayer (bagasse/coir/bagasse) composite is found to be higher and the same in all other patterns.
Monteiro et al. (1998) studied the possible uses of bagasse waste as reinforce- ment material in composites of polyester matrix. Preliminary results have attested this possibility. Homogeneous microstructures composites could be fabricated and the levels of their mechanical properties enable them to have practical appli- cations similar to the ones normally associated with wooden agglomerates. Future developments are expected to increase the performance and competitiveness of these composites as compared to those of other materials in the same structural class.
De Sousa et al. (2004) reported the effect of operating parameters on the mechan- ical performance of polyester composites (chopped bagasse based). The parameters to be evaluated were the “size of the material” and “molding pressure.” It has been noticed that composites made with bagasse fiber of #20 sieve size pretreated for sugar and alcohol extraction had good mechanical properties. Acharya et al. (2010) conducted experiments to determine the abrasive wear behavior of reinforced epoxy composite (bagasse fiber-based) in different directions which are named parallel orientation (PO), antiparallel orientation (APO), and normal orientation (NO) by using a abrasion wear tester (two body). Three different types of abrasives wear behavior have been observed in the composite in three directions and follow the fol- lowing trends: WNO < WAPO < WPO, where WNO, WAPO, and WPO are the wear in normal, antiparallel, and parallel directions of fibers orientation, respectively.
Satyanarayana et al. (2011) described an option for pretreatment of sugarcane- based bagasse fibers for fabrication of USP composite. Bagasse fibers were treated by different methods, namely, steam explosion and alkali washing. From the experiments, it is found that the hemicellulose amount and bagasse fiber acid-soluble lignin were reduced by steam explosion method significantly, while acid-insoluble lignin increased in equal proportion.
Satyanarayana et al. (2011) reported that the DMA shows that the application of a small oscillatory mechanical tension leads to the deformation in solid environ- ment under a variation of frequency. The DMA curves of the PPC and the fiber composites are represented in Fig. 10. From the figure it is observed that in all devel- oped specimens a sudden decrease in the modulus is noticed (as shown in Fig. 10), under the temperatures above 0 °C. The Tg displacement (as shown in Fig. 9) is noticed at higher temperature ranges for pretreated fiber composite as compared to the neat matrix or bagasse-fiber-reinforced composites without pretreatment. This performance is because of the good interfacial adhesion of the treated fibers with the matrix.
Lignocellulosic fibers have good water absorption capacity which is also observed in composites reinforced with lignocellulosic fibers. Figure 10 represents the curve for water absorption.
Composites from Bagasse Fibers, Its Characterization and Applications 103
Fig. 9 Dynamic mechanical analysis (DMA) curves of polyester matrix and its composites a
polyester matrix (PPC);b polyester-as-received bagasse (AR-PC); and c polyester-surface treated bagasse (STB-WI and WIPC). (Reproduced with permission from Elsevier Ltd. Satyanarayana et al. (2011))
Fig. 10 Moisture absorption of polyester–bagasse composites containing a as-received bagasse
(AR-PC); b steam-exploded and washed bagasse (STB-WIPC); c steam-exploded + alkali-washed bagasse (STB-WIPC). (Reproduced with permission from Elsevier Ltd. (Satyanarayana et al. 2011))
D. Verma et al. 104
Verma et al. (2012) investigated and developed fly ash–bagasse fiber composite material which has been discussed. The bagasse fiber has been used in two different sizes for the developed material. In two developed composites, the diameter of ba- gasse fiber was varied between 13–16 and 83–95 µm in length. Correspondingly, in the other two developed composites, the length of bagasse fiber was varied from 1 to 5 mm. It was observed that the density decreases by mixing the fiber was more as compared to the composite having both bagasse fiber and fly ash. A bagasse fiber composite with size in the range of µm exhibited better tensile strength than the composite having bagasse fiber size in millimeter. The compressive strength of the material increases, if fly ash alone is used for the composite material but, when bagasse fiber was mixed with the fly ash, it was found that there was a decrease in the compressive strength. It was also observed that there was a reduction in the flexural strength of the material by mixing the bagasse fiber in the matrix.