Diesters Biolubricant Base Oil: Synthesis, Optimization, Characterization, and Physicochemical Characteristics

Table 1

Independent variables and their levels for D-optimal design of the esterification reaction.

Independent variables		Variable Levels
		−1	0	+1
(1) OL/HYOOA (mol/mol)	𝑋1	2	3	4
(2) SA/HYOOA (mol/mol)	𝑋2	0.7	1	1.3
(3) Temperature (ºC)	𝑋3	90	100	110
(4) Time (h)	𝑋4	5	6	7