Table 2.

Changes in the surface chemistry of plasma-treated PP samples characterized by water contact angles of a sessile drop, average atomic concentrations (without H), differences in the surface roughness measured before and after the treatment, and by tensile strengths derived from the single lap joint shear test. The error of the atomic concentration measurement was ∼1 at.%. The conditions used for treating the samples are shown in Table 1.

	WCA	C	O	N	Roughness	Tensile Str.
Sample	(${}^{\circ }$)	(at.%)	(at.%)	(at.%)	Diff. (nm)	(MPa)
Ref	99 ± 1	100				1.4 ± 0.1
Ar-f	74 ± 2	89	10	0.5	$-1$ ± 1	3.5 ± 0.3
ArO-f	76 ± 1	88	11	0.6	$-1$ ± 1	4.8 ± 0.3
ArN-f	67 ± 1	88	11	1.4	$-1$ ± 1	4.3 ± 0.3
ArN-$fo$	67 ± 1	89	10	1.6	2 ± 2	6.3 ± 0.4
Ar-s	36 ± 4	70	27	3	$-5$ ± 2	3.8 ± 0.2
ArO-s	58 ± 2	77	22	1	$-4$ ± 1	-
ArN-s	59 ± 3	72	20	8	$-3$ ± 1	4.5 ± 0.2