3.4.1. Textural characterization

range of carbon black. N772 provides high elasticity, low heat-up, good aging-resistance, and

Pyrolysis is a thermal treatment with limited oxygen by which organic materials are chemically decomposed by heat. It is a promising method by using waste materials such as biomass as feedstock to convert waste into energy and other valuable products. During the pyrolysis, large molecules break down into small molecules, resulting in carbonaceous materials, combustible gases, and condensable liquid hydrocarbons for renewable energy resources [39–42]. According to Sienkiewicz et al. [43], it is obvious that there is a significant potential of pyrolysis treatment based on ongoing works along with increasing cost of energy and petro-

The pyrolysis of coconut shell was performed in a Carbolite 11/150 laboratory scale rotary furnace (Carbolite, Hope Valley, UK) situated in a walk-in fume cupboard. As shown in Figure 3, a rotatory horizontal tubular quartz vessel with the capacity of almost 5 liters is suspended by air-tight rotary fixtures inside an electrically heated box-furnace. According to several studies, the rotation rate is set as 10 ramp/min. The temperature is controlled at 600C by the thermal system with a thermocouple in the box furnace. Nitrogen gas is introduced into the reaction vessel from the gas inlet ports at 550 ml/min flow rate [44]. The nitrogen flow maintaining in the vessel throughout the pyrolysis is to protect the char from oxidation and help to carry and remove the pyrolytic volatiles (oil and gas) toward the oil trap. At the same time, the noncondensable volatiles (gases) were vented from a small opening on the top of the

All the char samples after the pyrolysis were ground by wet TEMA milling using a vibratory disc mill (Tema Machinery Company Ltd., UK). Wet milling is used for the more intensive and efficient properties than dry grinding since it can break the char samples into finer

superior dynamic performance to the technical rubber products or tire frames.

3.2. Pyrolysis process

94 Advanced Surface Engineering Research

leum and resources such as carbon black.

oil trap to the fume cupboard.

Figure 3. Illustration of rotary furnace.

3.3. Postpyrolysis grinding by wet TEMA milling

Surface area of the samples were characterized by liquid nitrogen (at 77 K) adsorption and desorption method using the OMNISORP 100. The BET surface area can be calculated with the isotherms by using the Brunauer-Emmett-Teller equation [46]. The t-plot method was used to find the micropore volume and the combined macropore and mesopore surface area [47]. The significant surface areas were concluded from the difference between the BET surface area and the macropore and mesopore surface area and used to establish the relationship between pore size distribution and rubber uptake capacity of the fillers.

### 3.4.2. Toluene extraction

Toluene extraction of the char filler was test according to the ASTM D 1618-99 (Standard Test Method for Carbon Black Extractables—Transmittance of Toluene Extract) [48]. This method covers the measurement of the degree of toluene discoloration by carbon black extractables and is useful in controlling the reaction process for the production of carbon black.

#### 3.4.3. pH value

Test Method A—Boiling Slurry of ASTM D1512-05 Standard Test Method for Carbon Black—pH value [49] was applied to obtain the pH value of the char filler. The pH value is very essential since it can affect the vulcanization of some rubber compounds.
