Page 77 - Handbook of Adhesion Promoters

70 Substrates - Surface Condition and Treat-

Figure 4.17. High resolution C1s XPS spectrum of Figure 4.18. Schematic view of sintering process
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PEEK treated at 7.83×10 W mm . [Adapted, by per- through the light induced substrate heating. [Adapted,
mission, from Wilson, A; Jones, I; Salamat-Zadeh, F; by permission, from Lesyuk, R; Jillek, W; Bobitski, Y;
Watts, JF; Int. J. Adh. Adh., 62, 69-77, 2015.] Kotlyarchuk, B, Microlectrnics Eng., 88, 3, 318-21,
2011.]
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intensities (above 10 W mm ) have disrupted the surface of the PEEK more than the
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lower laser power intensities (<10 W mm ). The water contact angle decreased with
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increasing laser power intensity. The oxygen-containing functional groups were created
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on the surface. Figure 4.17 shows that typical functional groups increased on PEEK’s
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surface by laser treatment. A specific laser power intensity of 10 W mm , at a wave-
length of 1064 nm is the threshold laser power intensity required to chemically change the
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surface of PEEK for improved adhesive bonding in medical applications.
A rapid patterning method for interconnects fabrication combines the ink-jet printing
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of silver nanoparticles and laser sintering on the ceramic substrate (Figure 4.18). This
treatment permits curing of printed layers without damaging substrate and it is time-sav-
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ing in comparison to thermal (furnace) sintering.
4.2.8 UV
The adhesion between a polychloroprene adhesive and an ethylene vinyl acetate copoly-
mer containing 12 wt% vinyl acetate was improved by treatment with UV radiation. 48
Wettability was increased, carbon-oxygen polar moieties were produced, and surface
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roughness was created. UV radiation treatment time was 5 min using lamp emitting radi-
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ation of 254 nm with power of 10 mW/cm at distance of 2 cm.
Adhesion at the thermoset/thermoplastic interface was achieved by direct co-curing
of an UV irradiation treated PEEK film with aerospace grade carbon/epoxy prepregs. 49
The PEEK films were irradiated using low pressure mercury short-wavelength ultraviolet
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lamps operating at the spectral wavelengths of 184.9 and 253.7 nm. The spectral line at
184.9 nm generates ozone and atomic oxygen by photolysis of oxygen gas in an endother-
mic reaction, while the spectral lines at 253.7 nm are easily absorbed by single C–C bonds
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of hydrocarbons as well as ozone, during which reaction O is generated. The films were
placed in an enclosed volume at a distance of 5.1 mm from three 30 W tube UVC-lamps,
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installed 50 mm apart. Exposure time was from 5-60 min (15-30 min sufficient). The
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chemical structure of PEEK surface was modified which has improved the wettability.
Ethylene-vinyl acetate copolymers applicable to sport sole manufacturing contain
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polyethylene (LDPE) to improve abrasion resistance and decrease cost. The blend has