Evaluating and interpreting biodegradability of a tree bark–based green composite through tensile properties

In this study, the barks of several tree species, e.g., calabrian pine (Pinus brutia Ten.), cedar (Cedrus libani), eucalyptus (Eucalyptus camaldulensis), acacia (Robinia pseudoacacia), Anatolia chestnut (Castanea sativa), and Turk oak (Quercus cerris), were phenolated by using sulfuric acid as a catalyst at a temperature of 130 ◦C for 1 h. The obtained phenolated barks were cured by using hexamethylenetetramine (HMTA) at about 190 ◦C under pressure. Subsequently, the tensile properties (tensile strength, Young’s modulus, elongation) of the phenolated bark-based molding materials were also evaluated by comparing with those of phenolated poplar woodand commercial novolak resinbased molding ones. The results showed that that the tensile properties (tensile strength, Young’s modulus and elongation) of the phenolated bark-based moldings was affected by the concentration of the catalyst, and except for Young’s modulus and tensile elongation, the tensile strength values of them obtained at high enough catalyst concentrations between 1–2% was similar to those of the commercial novolak resin-based ones. According to the inventory for 1978, the amounts of tree bark production in the earth reach approximately 338,781,000 m3, which is great deal of lignocellulosic potential, containing various natural polymers, such as cellulose, lignin, condensed tannins, resin acids and so on, for many industries. However, the bark has been most commonly burned in order to get energy for any purpose for a long time, which is the simplest way of using a lignocellulosic materials [1]. On the other hand, rising oil prices and the high energy needs in the production of synthetic polymers require the urgent future use of bio-energy sources such as bark wastes or the other ligno-cellulosics in much more useful applications such as plastic industry rather than in energy production. Meanwhile, a big necessity to develop degradable polymeric products and use the lands

The purpose of this study was to establish the relationship between the chilling resistance of rubber trees and the bark-bleeding characteristics caused by chilling stress, considering physiological indicators in rubber tree bark, cell wall chemical components, fiber morphologies, and tensile properties. This offered a unique perspective for examining the underlying mechanisms of latex bleeding and chilling stress in Hevea brasiliensis. One-year-old seedlings and two-year-old twig segments in five- and twenty-one-year-old rubber trees (5YB and 21YB) were used to compare the age-mediation differences in their various parameters. Meanwhile, the LT50 values were calculated with Logistic regression analysis of relative electrical conductivity (REC) data under gradient low temperatures. Subsequently, changes in corresponding parameters of 1-year-old seedling stem bark at different ages were determined, and the bark-bleeding characteristics of seedlings and twig segments were analyzed under artificially simulated chilling stress, respectively. A correlation analysis between semi-lethal temperature (LT50) values, relative water content (RWC) values, bark-bleeding characteristics, cell-wall chemical component contents, fiber dimensions, and tensile property parameters was implemented to estimate interrelationships among them. The LT50 values ranged from -2.0387 °C to -0.8695 °C. The results showed that the chilling resistance order of rubber trees at different ages was as follows: 21YB (2-year-old twig bark from 21-year-old rubber trees) > 5YB (2-year-old twig bark from 5-year-old rubber trees) > SLB (semi-lignification bark in 1-year-old seedlings) > GB (green bark in 1-year-old seedlings). The chilling resistance of seedlings and twig segments in rubber trees was highly positively (p < 0.001) related to fiber morphologies. Chilling-induced bark-bleeding characteristics were significantly correlated (p < 0.001) with fiber morphologies, bark tensile properties, and cell-wall components. The analysis data in this study contribute towards building a comprehensive understanding of the mechanisms of chilling-induced bark bleeding needed not only in rubber tree cultivation but also in sustainable rubber production.

This paper investigates the extraction and characterization of fibres from the bark of the ficus nekbudu tree. The Ficus Nekbudu Fibres (FNF) was extracted from the bark by retting in water and then treatment with sodium hydroxide solution. The extracted FNF was analysed for chemical composition, physical, tensile, surface, structural and thermal stability properties. Findings on the chemical composition indicated that FNF has cellulose (49.9 %), lignin (13.4%), ash (7.1%) and water content (8.1%). From the physical investigation it was found that FNF has density (1.42 ± 0.005 g/cm3 ) and moisture regain (9.2 ±0.3%). From mechanical investigation it was found that FNF has tenacity (2.56 ± 0.75 cN/dtex) and extension at break (9.23 ± 2.85%). SEM analysis indicated that FNF has rough surface with some surface impurities. The ATR- FTIR analysis indicates that the FNF has Total Crystallinity Index (TCI) and Lateral Order Index (LOI) of 0.52 and 0.41, respectively. Thermal analysis indicates that the FNF are stable up to 250°C.