Researchers from Southwest Jiaotong University prepared a series of hindered phenol hybrid carboxylated nitrile rubber composites with different types and contents of hindered phenol
Hindered phenols are nonmetallic stabilizers and antioxidants that function by scavenging peroxy radical intermediates in the oxidation process. They are used to reduce the change in polymer color, prevent polymer chain degradation, and minimize the consumption of the hindered phenols during processing. They are effective over a wide range of temperatures and offer protection during melt processing, end use, and long-term storage. Some hindered phenols (such as AO-20, AO-50) also contribute to the light stability of plastics.
Now, a team of researchers from Southwest Jiaotong University assessed the compounds that consisted small molecules with different structures and the dynamic mechanical properties of hindered phenol and studied the effect of hydrogen bonds on the properties of organic hybrid damping materials. The team also classified the crystallization properties of small molecules and hydrogen bonds. Molecular dynamics was used to simulate the alteration of hydrogen bonds along different structures of hindered phenolic materials. The team conducted aging test at a temperature of 60 °C for four hours. The adopted samples were tested within two hours of the preparation to avoid the deterioration of the original sample and the remaining samples were stored at low temperature.
The team found that integrating a hindered phenol into hybrid carboxylated nitrile rubber (XNBR) can enhance the loss factor of the material. Moreover the glass transition temperature of the compound moved to a higher temperature. X-ray diffraction (XRD) was used to study the crystallization of hindered phenol as the damping performance characterization showed compounds of different hindered phenols had different properties during the aging test. XRD results stated that the high damping capacity of organic hybrid damping materials is due to hydrogen bonding. Moreover, hydrogen bonds disappear in the material system, owing to the crystallization of hindered phenols, thereby decreasing the material properties. The research was published in the journal MDPI Materials on March 27, 2019.
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