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3.3 Sample preparation
The materials used in this project are nano calcium carbonate powder nano CaCO
3
, recycle rubber BR and SBR, epoxy resin and epoxy hardener. These materials are
mixed using vary nano CaCO
3
powder particle size and percent content. The nano- size calcium carbonate nano-CaCO
3
used in this study, 20nm, was supplied by Maju Tek.
The compounding formulations are summarized in Table 1. The mixing ratio of the epoxy, hardener, recycle rubber and nano CaCO3 powder was kept constant for all
experiments as 1:0.7:0.4 by weight, respectively. In this study five different weight percent 0, 2, 4, 6, and 8 wt of nano CaCO3 powder will be vary too.
Table 3.1 : Compounding formulation
Weight of Nano CaCO
3
Weight gram Epoxy Resin
Epoxy Hardener
Recycle Rubber
Nano CaCO
3
Powder 100
70 40
2 100
70 40
4.2 4
100 70
40 8.4
6 100
70 40
12.6 8
100 70
40 16.8
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3.3.1 Mechanical Stirring
The tecycle rubber rubber, epoxy resin, epoxy hardener and nano CaCO3 were performed using a mechanical stirring and heated at temperature 60 °C
for 5 min. The recycle rubber and epoxy resin was added and mixed using the mechanical stirrer mill at speed 500 rpm for 5 min. Then nano-CaCO
3
powder were added in the same manner, at speed 500rpm for 5 min. Beside that the mechanical stirring also been applied to give the shear force to make
this mixture fully homogenized.
Figure 3.2 : Mechanical Stirrer Apparatus
3.3.2 Furnace
A furnace can heat materials, typically metals, to very high temperatures and carry out processes such as brazing, sintering and heat treatment with high
consistency and low contamination. In a vacuum furnace the product in the furnace is surrounded by a vacuum.
The absence of air or other gases prevents heat transfer with the product through convection and removes a source of contamination. Some of the
benefits of a vacuum furnace are:
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•
Uniform temperatures in the range 2000–2800°F 1100–1500°C
•
Temperature can be controlled within a small area
•
Low contamination of the product by carbon, oxygen and other gases
•
Quick cooling quenching of product.
•
The process can be computer controlled to ensure metallurgical repeatability.
Heating metals to high temperatures normally causes rapid oxidation, which is undesirable. A vacuum furnace removes the oxygen and prevents this from
happening
3.3.3 Differential Scanning Calorimetry
Differential Scanning Calorimetry DSC is a powerful analytical tool which directly measures the stability and unfolding of a protein, lipid, or nucleic
acid. In DSC, the biomolecule is heated at a constant rate and there is a detectable heat change associated with thermal denaturation. DSC measures
the temperatures and heat flows associated with transitions in materials as a function of temperature or time in a controlled atmosphere. This technique
provides quantitative and qualitative information about physical and chemical changes that involve endothermic or exothermic processes, or
changes in heat capacity. In a single DSC experiment, can determine:
•
Transition midpoint - T
m
•
Enthalpy ΔH and heat capacity change ΔCp associated with unfolding
A biomolecule in aqueous solution is in equilibrium between the native folded conformation and its denatured unfolded conformation. The
stability of the native state is based on the magnitude of the Gibbs free energy ΔG of the system and the thermodynamic relationships between enthalpy
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