Ubim Fiber (Geonoma baculífera): A Less Known Brazilian Amazon Natural Fiber for Engineering Applications

Abstract

The production of synthetic materials generally uses non-renewable forms of energy, which are highly polluting. This is driving the search for natural materials that offer properties similar to synthetic ones. In particular, the use of natural lignocellulosic fibers (NLFs) has been investigated since the end of 20th century, and is emerging strongly as an alternative to replace synthetic components and reinforce composite materials for engineering applications. NLFs stand out in general as they are biodegradable, non-polluting, have comparatively less CO2 emission and are more economically viable. Furthermore, they are lighter and cheaper than synthetic fibers, and are a possible replacement as composite reinforcement with similar mechanical properties. In the present work, a less known NLF from the Amazon region, the ubim fiber (Geonoma bacculifera), was for the first time physically characterized by X-ray diffraction (XRD). Fiber density was statistically analyzed by the Weibull method. Using both the geometric method and the Archimedes’ technique, it was found that ubim fiber has one of the lowest densities, 0.70–0.73 g/cm3, for NLFs already reported in the literature. Excluding the porosity, however, the absolute density measured by pycnometry was relatively higher. In addition, the crystallinity index, of 83%, microfibril angle, of 7.42–7.49°, and ubim fiber microstructure of lumen and channel pores were also characterized by scanning electron microscopy. These preliminary results indicate a promising application of ubim fiber as eco-friendly reinforcement of civil construction composite material.

Periquiteira (Cochlospermum orinocense): A Promising Amazon Fiber for Application in Composite Materials

“…The crystallinity index value obtained from the periquiteira fiber was 70.49%. This result is comparable to other values reported from Amazonian NLFs, such as guaruman [25], buriti [30] and ubim [34].…”

“…The peak at 22.78 • , which indicates the crystalline part of the fiber was used to evaluate the MFA and calculated as 7.32 • . This value is similar to MFA values of other lignocellulosic fibers [25,34,38]. According to Junio et al, [38] low MFA values are considered to be favorable indicators of good mechanical properties, providing better fiber strength results.…”

“…The mean density value, obtained from the geometric method, was 0.43 g/cm 3 . This value is lower when compared to the densities of other NLFs from the Amazon, such as guaruman and ubim [25,26,34]. It is also observed, in Figure 3b, that the mean density decreases as the diameter increases.…”

“…This pattern may be related to the number of defects in the fiber structure, as observed in the micrographs, Figure 7, and also in the density pattern, Figure 3b, in relation to the diameter interval. Studies indicate that fibers with smaller diameters tend to present a uniform pattern with more compact microfibrils, fewer void spaces and, consequently, have greater strength [25,34]. However, in thicker fibers, there is a greater number of defects and microstructural porosity, which can cause a decrease in strength [61][62][63][64].…”

“…Several studies have revealed an increase in the search for NLFs that can be used to reinforce polymeric composites, among which those found in the Amazon region stand out [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]; for instance, curaua [23,29], buriti [19,30], mallow [27,35], carnauba [38] and titica vine [39]. In addition to Amazon fibers, several other NLFs are being studied as possible reinforcements for polymer composites.…”