Development of Particleboard from Green Coconut Waste

In this study, green coconut waste was successfully transformed into coconut fibre-based particleboards. In addition to urea-formaldehyde (UF), two types of green binder: BST00 (low ammoniated latex and epoxidized natural rubber latex-based) and BST20 (epoxidized natural rubber latex-based) were used in particleboard fabrication. The particleboards were fabricated using coconut pith and fibre with 15% binder loading through two pre-compression steps followed by a final hot compression at 140 °C for 15 mins at ∼2.1 MPa. Board properties such as density, thickness swelling (TS), water absorption (WA), and internal bond (IB) strength were determined in accordance with JIS A 5908 standard, except for modulus of rupture (MOR) (ASTM D1037). BST00-bonded particleboards exhibit the poorest properties among the three samples, making BST00 the least effective binder. BST20-bonded particleboards show the best overall properties with the highest density of ∼1 g/cm3, IB value of 0.416 MPa, MOR of 11.61 MPa, best water resistance with TS of 14% and WA of 24%. The UF-bonded particleboards have the highest MOR of 12.05 MPa. Overall, the UF- and BST20-bonded coir particleboards met the minimum JIS A 5908 requirement except density (0.4-0.9 g/cm3) and TS (<12%). The green binder BST20 has shown great potential to replace UF.

Internal Polymerization of Epoxy Group of Epoxidized Natural Rubber by Ferric Chloride and Formation of Strong Network Structure

In this work, studies are carried out to understand the crosslinking reaction of epoxidized natural rubber (50 mol% epoxy, ENR-50) by metal ion namely ferric ion (Fe3+, FeCl3, ferric chloride). It is found that a small amount of FeCl3 can cure ENR to a considerable extent. A direct interaction of the ferric ion with the epoxy group as well as internal polymerization enable the ENR to be cured in an efficient manner. It was also found that with the increased concentration of FeCl3, the crosslinking density of the matrix increased and therefore, the ENR offers higher mechanical properties (i.e., modulus and tensile strength). In addition, the glass transition temperature (tg) of ENR vulcanizate is increased with increasing concentration of FeCl3. Moreover, the thermal degradation temperature (Td) of the ENR-FeCl3 compound was shifted toward higher temperature as increasing concentration FeCl3.

Selectively Etched Halloysite Nanotubes as Performance Booster of Epoxidized Natural Rubber Composites

Halloysite Nanotubes (HNT) are chemically similar to clay, which makes them incompatible with non-polar rubbers such as natural rubber (NR). Modification of NR into a polar rubber is of interest. In this work, Epoxidized Natural Rubber (ENR) was prepared in order to obtain a composite that could assure filler–matrix compatibility. However, the performance of this composite was still not satisfactory, so an alternative to the basic HNT filler was pursued. The surface area of HNT was further increased by etching with acid; the specific surface increased with treatment time. The FTIR spectra confirmed selective etching on the Al–OH surface of HNT with reduction in peak intensity in the regions 3750–3600 cm−1 and 825–725 cm−1, indicating decrease in Al–OH structures. The use of acid-treated HNT improved modulus, tensile strength, and tear strength of the filled composites. This was attributed to the filler–matrix interactions of acid-treated HNT with ENR. Further evidence was found from the Payne effect being reduced to 44.2% through acid treatment of the filler. As for the strain-induced crystallization (SIC) in the composites, the stress–strain curves correlated well with the degree of crystallinity observed from synchrotron wide-angle X-ray scattering.