Thermal Stabilization Mechanism by Nanodiamonds
Nanodiamonds have the unique ability to protect organic materials from thermal degradation over 260 to 400℃. Workable temperature of general antioxidants is at most 250℃ in air because they decompose in high temperatures.
On the other hand, nanodiamonds can work in air temperatures over 300℃ due to thermal stability of their diamond structure. Nanodiamonds are more stable and unique additives to prevent oxidization than any other antioxidants.
Thus this unique carbon nano material can be applied to engineering plastics, oils, and rubber which are expected to be used in 260 to 400℃ temperatures.
A chain reaction of thermal oxidation is caused by free radicals and hydroperoxide intermediates. To stop the chain reaction, hindered phenols, phosphites, and thioethers are commonly used.
One of the key factors of antioxidation that nanodiamonds have hundreds of hydroxyl groups on their sp2 carbon layer. Phenolic hydroxyl groups on nanodiamonds can scavenge peroxy radical intermediates through the oxidation process. The basic mechanism of the function is the same as hindered phenols.
Value by Radical Scavenging
Improvement of Thermal Stability
Nanodiamonds can work as a thermal stabilizer for engineering plastics such as PEEK, polyimide and polyamideimide over 300 ℃, even though conventional antioxidants decompose at the condition.
Nanodiamonds are the world's first thermal stabilizer (antioxidant) which is available at unprecedented high temperature ranges.
|420℃ in Air||450℃ in Air||400℃ in Air|
Retaining Mechanical Property after Aging
Daicel investigated the thermal stability of nanodiamonds/Polyetheretherketone(PEEK) composites prepared via adding 0.5 wt % of nanodiamond powders during thermal kneading. Nanodiamonds/PEEK composites retain its mechanical properties after thermal aging in air at 300 ℃ for 1000 hours.
Retained Tensile Strength of nanodiamonds/PEEK Composites
after 1000hr Thermal Aging in Air at 300 ℃