Fiber pineapple

Mieck et al. [13], and Mukherjee et al. [14] on different types of flax and pineapple fibers. Their results show that tensile strength of flax fibers is remarkably more dependent on the length of the specimen than are usual glass fibers (Fig. 3). In contrast, tensile strength of pineapple fibers is less dependent on the length. The dispersion of the measured values is located mainly in the range of the standard deviation. 

Figure 3 Dependence of tensile-strength on test length, flax fibers [70], and pineapple fibers [88] compared with textile glass-fibers [8].

SEM can also be used for the interface analysis of composites. Figures 16a and 16b show the SEM of PMPPIC-treated and untreated pineapple fiber-rein-forced LDPE composites. Strong adhesion between fiber and matrix is evident from Fig. 16a, whereas Fig. 16b indicates fiber pullout [78]. 

Pineapple fiber showed higher (86.7%) antioxidant activity than orange peel fiber (34.6%), and myricetin was the major polyphenol identified in pineapple fiber (Larrauri and others 1997). 

Rept. 5, A Report on the Leaf Fibers of the United States, Detailing Results of Recent Investigations Relating to Florida Sisal Hemp, the False Sisal Hemp Plant of Florida, and Other Fiber-Producing Agaves Bowstring Hemp, Pineapple Fiber, New Zealand Flax, and Bear Grass, 1893. 

Mukherjee PS, Satyanarayana KG (1986) Structure and properties of some vegetable fibers -Part 2 Pineapple fiber. J Mater Sci 21 51-56... 

George J, Bhagawan SS, Thomas S (1998a) Improved interactions in chemically modified pineapple leaf fibre reinforced polyethylene composites. Cranpos Inlerf 5 201-223 George J, Bhagawan SS, Thomas S (1998b) Effects of environment on the properties of low-density polyethylene composites reinforced with pineapple fibers. Compos Sci Technol 58 1471-1485... 

George J, Sreekala MS, Thomas S, Bhagawan SS, Neelakantan NR (1998c) Stress relaxation behavior of short pineapple fiber reinforced polyethylene composites. J Reinf Plast Compos 17 651-672... 

Luo S, Netravali AN (1999) Interfacial and mechanical properties of enviromnent-fritardly green composites made from pineapple fibers and poly(hydroxybutyrate-co-valerate) resin. J Mater Sci 34 3709-3719... 

Mohanty AK, Parija S, Misra M (1996) Ce(IV)-A(-acetylglycine initiated graft copolymerization of acrylonitrile onto chemically modified pineapple leaf fibers. J Appl Polym Sci 60 931-937 Mohanty AK, Khan MA, Hinrichsen G (2000) Surface modification of jute and its influence on performance ofbiodegradable jute-fabric/Biopol composites. Compos Sci Technol 60 1115-1124 Mohanty AK, Misra M, Drzal LT, Selke SE, Harte BR, Hinrichsen G (2005) Natural fibers, biopolymers and biocomposites an introduction. In Mohanty AK, Misra M, Drzal LT (eds) Natural fibers, biopolymers and biocomposites. Taylor Francis, FL, Boca Raton Mukherjee PS, Satyanarayana KG (1986) Structure and properties of some vegetable fibres Part 2 pineapple fiber. J Mater Sci 21 51-56... 

George J, Bhagawan SS, Thomas S (1996) Thermogravimetric and dynamic mechanical thermal analysis of pineapple fiber reinforced polyethylene composites. J Therm Anal 47 1121-1140... 

Natural fibers-reinforced polymer matrixes provide more alternatives in the materials market due to their unique advantages. Poor fiber-matrix interfacial adhesion may affect the physical and mechanical properties of the resulting composites due to the surface incompatibihty between hydrophilic natural fibers and non-polar polymers. The results presented in this chapter focus on the properties of palm and pineapple fibers in terms of their physical and chemical structure, mechanical properties and processing behavior. The final properties of these fibers with thermoplastics matrixes are also presented, paying particular attention to the use of physical and chemical treatments for the improvement of fiber-matrix interaction. 

Keywords Palm fibers, pineapple fibers, polypropylene, high-density polyethylene, adhesion, mechanical properties... 

The results presented in this chapterfocus on properties in terms of the physical and chemical structure of palm and pineapple fibers, mechanical properties, processing behavior and final properties of these fibers with thermoplastics matrixes, paying particular attention to the use of physical and chemical treatments for the improvement of fiber-matrix interaction. 

Pineapple fiber is rich in cellulose, has a relatively low cost and is abrmdantly available. Because of these characteristics munerous research studies are being carried out [38-44]. The fibers from pineapple have been applied as reinforcement in several polymeric matrices due to the advantages they present such as low cost, low density and high specific properties. 

Below is a brief description of modifications done on the surface of pineapple fibers to improve mechanical properties. 

Sipiao et al. [22] studied the mechanical properties of polypropylene (PP) composites reinforced with pineapple fiber-treated alkali solution. 

Pineapple fibers were extracted from the crown and dried at 80°C for 24 h. Afterwards they were groxmd in a mill and sieved. To remove the soluble extractives and to facilitate adhesion between fibers and matrix, the in-nature pineapple crown fibers were modified by pretreatment with alkaline solution 1% (w/v). Next the fibers were filtered in a vacuum filter and were washed with distilled water until neutral pH. Then, the fibers were dried in an oven at 100°C for 24 h. 

The pretreated pineapple fibers were mixed with the PP in a thermokinetic mixer with speed rate maintained at 5250 rpm, in which fibers were responsible for 5 wt% in the composition. After the mixture, composites were dried and groxmd in a mill. The composites were placed in an injector camera at 165°C and 2°C min heating rate in a required dimension pre-warm mold with specific dimensions for impact specimens. 

The mechanical properties of pretreated pineapple fiber-reinforced polypropylene (PP) composites were determined. Five specimens were analyzed, with dimensions in agreement with the ASTM D 6110, ASTM D638 and ASTM D790 standards. 

Sousa et al. [46] studied the mechanical properties of polypropylene (PP) composites reinforced with pretreated pineapple fibers with sulfuric solution. Pineapple fibers were extracted from residue SuFresh and dried at 80°C for 24 h. After being ground in a mill and sieved, the fibers were pretreated in a 350 L stainless steel reactor, under these conditions 1.0% (w/v) H SO solution in a 1 10 solid liquid ratio, 120°C for 10 min. 

The pretreatment of pineapple fibers evidenced the removal of these extractives, causing the elimination of the superficial layer of the contact area. As a consequence, an increase in the roughness of fibers was observed, which contributed to the increase of the adhesion between fibers and matrix (Figure 10.11). 

Figure 10.11. Morphology of the pretreated pineapple fibers from residue juice at different...

The pineapple fibers from the juice residue reinforced with polypropylene composites presented higher strength compared to modified fibers from the juice residue reinforced with polypropylene composites. 

The amount of reinforcement in the matrix also contributes to the increase in strength. The modification of the pineapple fibers from the juice residue improved the adhesion between fiber/matrix, facilitating the energy transfer of impact, which is one of the influencing factors of this property. However, the unmodified fibers also facilitated the adhesion this occurred because the acidity in the juice production favored treatment in the fibers from the residue. 

Pineapple (Ananas comosus), which is native to Brazil, is a tropical plant with leaves rich in cellulose. Being relatively inexpensive and abundantly available, pineapple fiber may be considered for polymer composite reinforcement. Today, pineapple leaves are a by-product of pineapple cultivation [3]. Devi et al. [43] investigated the dynamic mechanical behavior of pineapple leaf fiber-reinforced polyester composites. Threepopnatkul et al. [44] studied the effects of fiber surface treatments on the performance of pineapple leaf fiber-carbonate composite. 

The chemical content in pineapple fiber is similar to that in flax and jute fiber (Table 2.8), but the lignin content in pineapple leaf fiber is more than that in flax (2—7%) and less than that in Jute (10—18%). Composition and properties of pineapple leaf fiber and bundle fiber are shown in Tables 2.9 and 2.10 [11]. 

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