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

Table 3

Regression coefficients of the predicted quadratic polynomial model for response variables of the yield % of OLHYOOD.

Variables	Coefficients (β), yield % of OLHYOOD (Y)	𝑇	𝑃	Notability
Linear
𝑋1	−1.67	0.12	0.7286
𝑋2	2.50	0.40	0.5334
𝑋3	3.99	1.35	0.2594
𝑋4	10.83	19.83	0.0002	***
Quadratic
𝑋11	−0.59	4.580E-003	0.9474
𝑋22	−9.66	2.41	0.1512
𝑋33	7.96	0.85	0.3775
𝑋44	0.90	8.067E-003	0.9302
Interaction
𝑋12	2.49	0.46	0.5149
𝑋13	−0.36	9.453E-003	0.9245
𝑋14	0.92	0.063	0.8069
𝑋23	−2.85	0.60	0.4574
𝑋24	1.69	0.20	0.6624
𝑋34	−1.40	0.14	0.7116
𝑅^2	0.69

Notes: 𝑋₁=OL/HYOOA; 𝑋₂= SA/HYOOA; 𝑋₃= reaction temperature; 𝑋₄= reaction time.
** 𝑃<0.05; ***𝑃<0.01. T: 𝐹 test value.
See Table 2 for a description of the abbreviations.