Optimization of Environmentally Benign Polymers Based on Thymine and Polyvinyl Sulfonate Using Plackett-Burman Design and Surface Response

Table 1

Experimental variables used in the Plackett-Burman design.

Variable	Type	Units	Symbol	Low level	High level
pH	Numerical	^a	A	6	12
Concentration	Numerical	% g L^−1	B	2	10
Dyeing time	Numerical	Sec	C	30	120
Stability	Numerical	Day	D	1	30
Coating thickness	Numerical	μm	E	6.8	13.6
				Level one	Level two
Drying film^b	Categorical	^a	F	Yes	No
Comonomer ratio^c	Categorical	^a	G	1 : 1	1 : 4

^aNot applicable. ^bDrying as explained in Section 2.3. ^c1 : 1 = VBT : VPS₁, 1 : 4 = VBT : VPS₄.