Hydrophilic and adhesive properties of methacrylic acid‐grafted polyethylene plates

Abstract

SYNOPSISMethacrylic acid (MAA) was grafted onto polyethylene ( P E ) surfaces by simultaneous irradiation with UV rays in the liquid phase to estimate hydrophilic and mechanical properties for MAA-grafted PE plates. The amount of grafted MAA increased sigmoidally with UV irradiation time, and the higher grafted amount was obtained at higher monomer concentrations. With an increase in grafting of MAA, the wettabilities from the contact angles of water were enhanced and the refractive indices from the ellipsometry decreased. Though the contact angles remained constant above the grafted amount of 0.02 mmol/cm2, the refractive indices approached the value of PMAA around 0.009 mmol/cm2, indicating that the PE surfaces were fully covered with grafted PMAA chains. Then, at a fixed grafted amount, the grafted layer can absorb more water and the grafted P E plates possessed higher tensile shear adhesive strength, in case grafting was carried out at lower monomer concentrations. Surface properties depended on the density of carboxyl group at the surfaces of grafted layers, whereas adhesive properties depended on the structural properties of grafted chains as well as on the density of carboxyl group of the whole grafted layers. I NTRO DU CTlO NPolyolefins such as polyethylene ( P E ) and polypropylene (PP) have good mechanical properties, but their surfaces are inert or hydrophobic. Such surfaces will result in poor adhesivities or wettabilities. Therefore, in some cases, the addition of new properties to such polymer substrates is required while concurrently leaving their bulk properties unchanged. Several techniques such as photo-, radiation-, and plasma-initiated graftings are available for modifying polyolefins, of which the photografting is expected to be the most convenient technique. An advantage of this technique is that the location of grafting can be restricted to the polymer surfaces without affecting any bulk properties because of the lower energy of the used UV rays. Many studies have been carried out for the hydrophilization of polymer

Thermo-responsive Properties of Surface Layer of Poly(tetrafluoroethylene) Plates Grafted with N-Isopropylacrylamide by Oxygen Plasma-treatment and Photografting.

“…The wettabilities of PTFE-gPNIPAAm surfaces toward water showed larger values at 25 °C than those at 40 °C. The reason that the wettabilities of PTFE-g-PNIPAAm surfaces at 40 °C did not show a considerable increase with a rise in the degree of grafting of PNIPAAm is attributed to the formation of dense layers resulting from the hydrophobic interaction among isopropyl groups of grafted PNIPAAm chains in the most upper region [4]. From the relation between N 1 s/C1 s and F 1 s/C1 s values of PTFE-g-PNIPAAm plates shown in Relation between the intensity of Fls/Cls and Nls/Cls ratios l~1J/V1V Figure 3 Contact angles (cos 0) of PTFE-gPNIPAAm prepared at 60 °C and 120 mm with the grafted amount of NIPAAm onto PTFE plate (N1s/Cls) Figure 4 Thickness of the grafted layer of PTFE-g-PNIPAAm prepared at 60 °C and irradiation time of W ray for 120 min.…”

Adhesion of ultrahigh molecular weight polyethylene plates photografted with hydrophilic monomers and evaluation of failure location by X‐ray photoelectron spectroscopy

“…25 The constant intensity ratios shown in Tables I and II were a little lower than these values. So, although the UHMWPE surfaces are fully covered with grafted polymer chains of PMAA or PAA, a small amount of PE chains are intermingles with grafted polymer chains of PMAA or PAA in the grafted layers formed on the UHMWPE plates.…”

“…The grafted UHMWPE plates were immersed in distilled water at 25 C for 24 h. Then, the grafted UHMWPE plates were taken out of water, blotted with filter paper to remove water attached to their surfaces, and weighed as quickly as possible. Water absorptivity was estimated from the amount of absorbed water according to eq.…”

“…The contact angles of water on the grafted UHMWPE plates were measured by a sessile drop method at 25 C with a Kyowa Kagaku TYP-QI-type goniometer to estimate their wettability. 18,19 At least 10 contact angles were averaged to obtain the reliable data to calculate the cos h values.…”

Effect of DC glow discharge treatment on the surface energy and surface resistivity of thin film of polypropylene

“…12 Essentially adhesion of an adhesive to solid surface depends upon wetting. 13 Wetting is qualitatively defined by reference to a sessile liquid drop resting on a solid surface at equilibrium. Information obtained from contact angle measurement for a wide range of solid substrates has proved vital to the formulation of biocompatible, adhesive and composite materials and in generating fundamental understanding of solid-solid and solid-liquid intermolecular interactions.…”