Adhesion and tack of polymers: Influence of mechanical properties and surface tensions

AbstractThe adhesion of various polymers used as model adhesives, polyisobutylene, polyacrylates etc. has been investigated by means of an apparatus measuring the adhesive failure energyw in dependence on contact time, contact pressure, rate of separation, and temperature. The adhesive failure energy of adhesive joints formed with low contact pressure during a short contact time is called “tack”. After a sufficiently long contact time and with a high bonding pressure an adhesive joint exhibits its maximum energy of separationwm.The viscoelastic properties of the model adhesives were characterized by creep experiments in dependence on time and temperature. The surface tension of the polymer adhesives and adherents could be determined by contact angle measurements. Adhesion measurements of polyisobutylene on a number of adherents were carried out in air and in various liquids in order to obtain information about the influence of surface tension on tack and maximum adhesive failure energy. wm can be written as the product of two terms: the thermodynamic work of adhesionWAwhich is related to the surface and interfacial tensions of adhesive and adherent and a dimensionless function dependent on temperature and rate of separation which describes the viscoeleastic properties of the adhesive and which obeys the rate-temperature superposition principle known from linear viscoelasticity. The tack is related to incomplete bond formation and cannot be described in the same manner. It is, however, strongly dependent on the viscoelastic properties of the adhesive showing a maximum at about 50 to 70 °C above the glass transition temperature. It is, moreover, influenced by the compliance in the plateau range above the glass transition which is determined by the entanglement network of the polymer. Wetting of the adherent by the adhesive is a further important condition for high tack values which is fulfilled if the adherent has a higher surface tension than the adhesive.

[1]  L. Girifalco,et al.  A THEORY FOR ESTIMATION OF SURFACE AND INTERFACIAL ENERGIES. III. ESTIMATION OF SURFACE ENERGIES OF SOLIDS FROM CONTACT ANGLE DATA , 1960 .

[2]  Studies on tack of pressure–sensitive adhesive tapes , 1970 .

[3]  G. Kraus,et al.  Morphology and Viscoelastic Behavior of Styrene-Diene Block Copolymers in Pressure Sensitive Adhesives , 1976 .

[4]  Ludwig Wilhelmy.  Ueber die Abhängigkeit der Capillaritäts‐Constanten des Alkohols von Substanz und Gestalt des benetzten festen Körpers , 1863 .

[5]  Y. Tamai,et al.  Experimental analysis of interfacial forces at the plane surface of solids , 1967 .

[6]  L. Lee.  Adhesion and Adsorption of Polymers , 1980 .

[7]  Pressure–Sensitive Adhesives , 1973 .

[8]  J. Ferry.  Viscoelastic properties of polymers , 1961 .

[9]  R. Good.  Surface free energy of solids and liquids: Thermodynamics, molecular forces, and structure , 1977 .

[10]  A. Gent,et al.  Adhesion of viscoelastic materials to rigid substrates , 1969, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[11]  D. K. Owens,et al.  Estimation of the surface free energy of polymers , 1969 .

[12]  H. Oser,et al.  Effect of Molecular Weight on Viscoelastic Properties of Polymers as Predicted by a Molecular Theory , 1963 .

[13]  Mohamed A. Mostafa,et al.  Acid-Base Interactions in Polymer Adsorption , 1978 .

[14]  J. R. Dann,et al.  Forces involved in the adhesive process: I. Critical surface tensions of polymeric solids as determined with polar liquids , 1970 .

[15]  M. Sherriff,et al.  Mechanism for the action of tackifying resins in pressure‐sensitive adhesives , 1973 .

[16]  Egon Matijević,et al.  Surface and Colloid Science , 1971 .

[17]  A. Gent,et al.  Effect of Wetting Liquids on the Strength of Adhesion of Viscoelastic Material , 1972 .

[18]  F. Fowkes,et al.  DETERMINATION OF INTERFACIAL TENSIONS, CONTACT ANGLES, AND DISPERSION FORCES IN SURFACES BY ASSUMING ADDITIVITY OF INTERMOLECULAR INTERACTIONS IN SURFACES , 1962 .

[19]  D. H. Kaelble,et al.  Peel Adhesion: Influence of Surface Energies and Adhesive Rheology , 1969 .

[20]  L’adhésion de matériaux viscoélastiques. Aspects thermodynamique et rhéologique , 1973 .

[21]  F. R. Schwarzl,et al.  On the interconversion between viscoelastic material functions , 1970 .

[22]  G. Hamed,et al.  Relationship between the cohesive strength and the tack of elastomers , 1983 .

[23]  W. Zisman,et al.  The spreading of liquids on low energy surfaces. I. polytetrafluoroethylene , 1950 .

[24]  A. Zosel.  Mechanical behaviour of coating films , 1980 .

[25]  D. Kaelble,et al.  A Reinterpretation of Organic Liquid-Polytetrafluoroethylene Surface Interactions , 1970 .

[26]  G. Kraus,et al.  Tack and Viscoelasticity of Block Copolymer Based Adhesives , 1979 .