Abstract
Ultra-fine oil palm ash (OPA) particles were successfully prepared using ultrasonication along with optimal chemical deagglomeration. The influence of chemical treatment by sodium hydroxide (NaOH) solution on the OPA particles was found to be an important factor in enhancing deagglomeration efficiency. The average particle size of the original OPA (41.651 μm) decreased remarkably more than 130 times (0.318 μm) with an obvious increase of Brunauer–Emmet–Teller (BET) surface area after treating the OPA with 3M NaOH, followed by ultrasonication for 30 min. The changes in particle size and surface morphology were investigated using transmission electron microscopy and scanning electron microscopy. Moreover, the chemical functional groups of the untreated and treated OPA showed different patterns of infrared spectra by the presence of sodium carbonate species owing to the effect of NaOH treatment. The incorporation of both untreated and treated OPA in natural rubber by increasing their loading can improve cure characteristics (i.e., reducing optimum cure time and increasing torques) and cure kinetic parameters (i.e., increasing the rate of cure and reducing activation energy). Nevertheless, the strength, degree of reinforcement, and thermal stability of treated OPA as well as wettability between treated OPA particles and NR were greater than that resulting from the untreated OPA.
Highlights
The utilization of oil palm ash (OPA), which is generated from the incineration of an agricultural waste from palm oil residues, has gained more attention in recent years because it is widely available without cost, and because of its high silica content which has specific characteristics, such as high porosity, high Brunauer–Emmet–Teller (BET) surface area, and a low coefficient of thermal expansion
The results showed that the particle size of the untreated OPA was in a range of 1−100 μm, with no particles smaller than 1 μm being detected
In order to evaluate the effect of modify physical properties of OPA after treatment with NaOH accompanying with ultrasonication compared with untreated OPA, which was only applied by ultrasonication, in rubber composite, glass transition temperature (Tg ) is a well-known parameter to measure this effect by relating to the temperature at initiating rubber chain mobility
Summary
The utilization of oil palm ash (OPA), which is generated from the incineration of an agricultural waste from palm oil residues (e.g., palm fiber, shells, and empty fruit bunches), has gained more attention in recent years because it is widely available without cost, and because of its high silica content which has specific characteristics, such as high porosity, high Brunauer–Emmet–Teller (BET) surface area, and a low coefficient of thermal expansion. The focus of the research was optimizing conditions to prepare ultra-fine OPA particles by applying the combination techniques of high-intensity ultrasonication and alkaline (NaOH) treatment in order to improve their characteristics and properties (e.g., particle size and shape, specific surface area, and chemical surface) with the aim of enabling the reuse of the OPA as a function of reinforcing filler in rubber composite and thereby deriving both economic and environmental benefits
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