Synthesis of multifunctional double long chain tricyclic borate coupling agents and their effect on the properties of GCC/HDPE composites

HDPE has attracted significant attention owing to its outstanding corrosion resistance, ease of processing, and cost effectiveness. Nevertheless, it has low toughness and is prone to aging, which results in a decline in mechanical properties and restricts its application in special fields. Using diethanolamine, boric acid, phenol, 2,4,6 -trichloro- 1,3,5 -triazine and long chain primary amines as raw materials, a series of multifunctional double chain tricyclic borate coupling agents 8a-f with novel structures were designed and synthesized. The structure of the target compounds was characterized by FT-IR and 1 H NMR. Thermal analysis showed that the double long chain tricyclic coupling agents had high thermal stability and the thermal decomposition temperature was as high as 270 °C. The oil absorption value of GCC powder treated with compound 8f decreased from 30.4  g/100 g– 13.6  g/100 g, and the contact angle increased from 0° to 135.4° . Compared with the unmodified composite, the mechanical properties of the modified GCC/HDPE composite were significantly enhanced, and its impact strength, tensile strength and bending strength were increased by 48.7  %, 48.6  % and 58.2  %, respectively. After 1000  h of UV aging, the tensile strength of the modified composite decreased by only 0.6  %, and there was no yellowing phenomenon, indicating that it has excellent aging resistance. This study provides a reference strategy for the development of functional coupling agents and high-performance composite materials.