Yoshihisa Kano

Estimation of surface tension and surface segregation of poly(ethyl acrylate)/poly(vinylidene fluoride-co-hexafluoro acetone) blends

Abstract The surface tensions (γ) of poly(ethyl acrylate) (PEA)/poly(vinylidene fluoride- co -hexafluoro acetone) (P(VDF-HFA)) blends were estimated by means of the contact angles with organic liquids Θ and bulk pressure-volume-temperature (PVT) properties. Two methods of estimation provided different γ values related to the surface segregation behaviour and the rearrangement. The change of γ against volume fraction of P(VDF-HFA) for PEA/P(VDF-HFA) blends was calculated using thermodynamic theory on γ of miscible polymer blends presented by Kammer. Finally, the surface segregation behaviour of P(VDF-HFA) component could also be expressed with the experimental data of γ and the Kammer theory.

Surface segregation and miscibility in blends of poly(ethyl acrylate) with poly(vinylidene fluoride-co-hexafluoroacetone)

In blends of poly(ethyl acrylate) (PEA) and poly(vinylidene fluoride-co-hexafluoroacetone) [P(VDF-HFA)], surface segregation of the P(VDF-HFA) component was confirmed by X-ray photoelectron spectroscopy. The PEA/P(VDF-HFA) blends exhibited lower critical solution temperature phase behaviour, with a critical temperature of 150°C. Since the surface tension value of P(VDF-HFA) is lower than that of PEA, this may influence surface segregation behaviour in PEA/P(VDF-HFA) blends. Surface segregation results of the PEA/P(VDF-HFA) blends are compared with those from a previous study on immiscible acrylate copolymer/fluoro copolymer blends.

Adhesive polymer: Intermacromolecular interaction in fluid solution studied by fluorescence depolarization method

Abstract The fluorescence depolarization of the anthryl groups attached to poly(styrene-maleic anhydride) [P(St-MA)] has been examined in mixtures of various acrylic adhesive polymers with toluene for weight fractions ranging from 0 to 0.25. It is clear that the relative mean rotational relaxation time of the anthryl groups sharply increases with increasing concentration of poly(2-ethylhexylacrylate) (PEHA) containing about 5% acrylic acid units and 10% vinyl acetate units. It may be concluded that an excellent adhesive polymer is made with acrylic acid units as agents for intra- and interaction and vinyl acetate units as depression agents for acrylic acid units and agents for strong PEHA-P(St-MA) interaction.

MISCIBILITY AND PRESSURE-SENSITIVE ADHESIVE PROPERTIES OF POLY(VINYLETHYLENE-CO-1,4-BUTADIENE)/TERPENE RESIN BLENDS

Abstract The pressure-sensitive adhesive properties of miscible blends of poly(vinylethylene- co -1,4-butadiene) (V-BR) with terpene resins were investigated on varying both the random copolymer composition (vinyl content) and the blend composition. The V-BR with 47.4 wt% vinyl content was found to be a remarkable rubber for use as a base polymer for a blend adhesive. In V-BR(47.4)/terpene resin blends, excellent pressure-sensitive adhesive properties were revealed for 50 50 blends. The good results for the adhesive properties were interpreted in terms of the dynamic mechanical behaviour of the blends.

Adhesive polymer. Fluorescence depolarizations of chromophores in adhesive agent on poly(ethylene terephthalate) base film

Abstract The fluorescence depolarizations of chromophores have been measured in adhesive agent on poly(ethylene terephthalate) film. The emission anisotropies of chromophores are influenced on increasing the thickness of the layer of adhesive polymer or poly(ethylene terephthalate) base film. These results are briefly discussed.

Acrylate Copolymer/Ultraviolet Curable Oligomer Blends as Pressure-sensitive Adhesives

Abstract For the blends of acrylate copolymer [poly(2-ethylhexyl acrylate-co-acrylic acid); P(2EHA-AA)] with ultraviolet (UV) curable oligomer [urethane acrylate oligomer; UAO], pressure-sensitive adhesive (PSA) properties, such as peel adhesion, probe tack, and holding power were examined. The values of peel adhesion and probe tack of the P(2EHA-AA)/UAO blends were dramatically reduced by UV irradiation. On the other hand, all blends had a high holding power even if these blends were cured by UV irradiation. The mechanism of reduced PSA properties was investigated via dynamic mechanical properties, DSC, and dynamic contact angle (DCA). The peel adhesion decreased monotonically with increasing storage modulus, E′, and loss modulus, E″, for all non-UV and UV-cured blends. Since modulus values and glass transition temperatures, Tg, of these blends after UV irradiation were higher than those of these blends before UV irradiation, we judged that the reduced peel adhesion and probe tack values were caused by the modulus increase and the Tg increase due to UV irradiation. In other words, the ability of the deformation energy of UV-cured blends to influence the adhesive tests was reduced by the curing process. The DCAs of non-UV-cured blends were the same as those of UV-cured blends. We presumed that the segment mobility of the polymer chain on the surface did not contribute to the reduced peel adhesion and probe tack values.

Contact angle of organic liquids on poly(2-ethylhexyl acrylate-co-acrylic acid)

Abstract The contact angles of poly(2-ethylhexyl acrylate-co-acrylic acid) (P(2EHA-AA)) with organic liquids, such as dispersion, polar and hydrogen bonding liquids, were investigated. The contact angle ϑ of organic liquids on P(2EHA-AA) decreased exponentially with contact time t, i.e. log ϑ = − K log t. It was suggested that the proportional constant K was influenced by the liquids surface tension γL, viscosity and glass transition temperature of P (2EHA-AA).

Effect of substrate on gradient domain morphology formed in acrylate copolymer/fluoro-copolymer blends

Abstract The effect of the substrate on the gradient domain morphology was investigated for immiscible blends of poly(2-ethylhexyl acrylate-co-acrylicacid-co-vinylacetate) [P(2EHA-AA-VAc)] and poly(vinylidene fluoride-co-hexafluoro acetone) [P(VDF-HFA)]. The blends were prepared on substrates of poly(dimethyl siloxane) (PDMS) coated on a liner and of poly(tetrafluoro ethylene) (PTFE) from a THF solution by coating. The chemical compositions and the cross-sectional morphology of the surface (surface in contact with air) and bottom (surface in contact with substrate) sides were examined by attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy. The P(2EHA-AA-VAc)/P(VDF-HFA) (50/50), (30/70) blends prepared on PDMS revealed a gradient domain morphology, whereas the (50/50) and (30/70) blends prepared on PTFE formed a sea-island type of phase separation structure. On the other hand, when the P(2EHA-AA-VAc)/P(VDF-HFA) (70/30) blend was prepared on PTFE, P(2EHA-AA-VAc) and P(VDF-HFA) components segregated at the surface and the bottom, respectively. We concluded that the affinity between P(VDF-HFA) and the substrates strongly influenced the formation of the gradient domain morphology and the surface segregation of P(2EHA-AA-VAc).

Poly(butyl acrylate)/poly(vinylidene fluoride-co-hexafluoroacetone) blends as pressure-sensitive adhesives

The pressure-sensitive adhesive (PSA) properties and dynamic mechanical properties were measured for the poly(butyl acrylate) (PBA)/poly(vinylidene fluoride-co-hexafluoroacetone) [P(VDF-HFA)] blends. The PSA properties of PBA adhesive could be controlled by blending P(VDF-HFA). In order to investigate the relationship between PSA properties and dynamic mechanical properties for PBA/P(VDF-HFA) blends, the master curves of the dynamic mechanical properties, such as storage modulus G′, loss modulus G′′, and dynamic loss tangent tan c, were constructed with the temperature-rate superposition principle. The probe tack and peel strength for PBA/P(VDF-HFA) blends were correlated with G′ and G′′. Since the G′ and G′′ values increased with increasing P(VDF-HFA) content, the holding power of PBA adhesive could be advanced by blending P(VDF-HFA).

Analysis of holding power in the blends of poly(butyl acrylate) with poly(vinylidene fluoride-cohexafluoro acetone)

Shear adhesion of pressure-sensitive adhesive tapes was evaluated for the blends of poly(butyl acrylate) with poly(vinylidene fluoride-co-hexafluoro acetone). The shear adhesion was determined as the function of the shear strain of pressure-sensitive adhesive tape against elapsed time under the shear stress. Shear adhesion of the blends increased with increasing poly(vinylidene fluoride-co-hexafluoro acetone) content. Experimental shear strain data were characterized with dynamic viscosity, stress and shear rate plot, and a generalized viscoelastic model of shear adhesion. However, the experimental data cannot be expressed with these viscoelastic properties. It is believed that shear adhesion is influenced by the viscoelastic properties and other factors (e.g., friction coefficient between adhesive and adherend or cohesive strength of adhesive polymer).