Creep resin type

Examples of creep effects covering environment, fibre type, resin type, effects of temperature, effects of strain and effects of overload are given in a variety of references at the end of this section. Creep effects are also affected by cyclic and intermittent loading. At cyclic frequencies above a few hertz the effects of heating of the material from hysteresis can be a factor in increasing creep. 

Because adhesives are used in very thin films and shearing is in the plane of the film, the shear strain can be large. Shanahan (1974) measured shear strains of up to 50% whilst the adherends of a lap-shear joint were creeping under load. This corresponds to a very substantial shear angle of 26 5°. The adhesive was a structural adhesive of the polyvinylformal/phenolic resin type (Redux 775, Ciba-Geigy, Ltd) and had a shear modulus of about 1 0 GN.m . ... 

Laminated beams (glulam), parallam (or LSL) and fingerjoints a flat pressed multilayer wood beam, thiek wood planks constituting the layers, used for structural exterior applications and bonded with PRF (phenol-resorcinol-formaldehyde) cold-setting resins, or MUF cold-setting resins, or even with certain types of polurethanes (although the use of these latter ones is only established in one country and can show creep and temperature-induced creep problems). The indi-... 

Stiffness, resistance to deformation under constant applied load (creep resistance), resistance to damage by cyclical loading (fatigue resistance), and excellent lubricity are mechanical properties for which acetal resins are perhaps best known and which have contributed significantly to their excellent commercial success. General-purpose acetal resins are substantially stiffer than general-purpose polyamides (nylon-6 or -6,6 types) when the latter have reached equilibrium water content. 

Acetal Copolymer (CELCON ) Two types of non-solvent adhesives are used, structural and non-structural. Most structural adhesives are based on thermoset resins and require the use of a catalyst and/or heat to cure. This type of adhesive is normally used in applications which require maximum bond strength and minimum creep of the adhesive joint under sustained loading. Many structural adhesives can be used continuously at temperatures up to 350 F, which is higher than the... 

In some epoxy systems ( 1, ), it has been shown that, as expected, creep and stress relaxation depend on the stoichiometry and degree of cure. The time-temperature superposition principle ( 3) has been applied successfully to creep and relaxation behavior in some epoxies (4-6)as well as to other mechanical properties (5-7). More recently, Kitoh and Suzuki ( ) showed that the Williams-Landel-Ferry (WLF) equation (3 ) was applicable to networks (with equivalence of functional groups) based on nineteen-carbon aliphatic segments between crosslinks but not to tighter networks such as those based on bisphenol-A-type prepolymers cured with m-phenylene diamine. Relaxation in the latter resin followed an Arrhenius-type equation. 

HDPE pipe is used in low pressure applications for transporting potable water, gas, acids, liquid hydrocarbons, oils, salt water, and other chemicals and solvents. Long-term load bearing, or creep, tests are essential to determine the life of PE pipe under pressure. HDPE pipe withstands pressures in short-term burst tests that are several times greater than long-term burst pressures because of the creep phenomenon. Broad molecular weight distribution resin, as obtained from chromium oxide catalysts, are ideal for most pipe applications. The introduction of superior, bimodal type, pipe resins in recent years has extended HDPE pipe applications. 

Adhesives can be broadly classified as being thermoplastic, thermosetting, elastomeric, or alloy blend. These four adhesive classifications can be further subdivided by specific chemical composition as described in Tables 7.20 through 7.23. The types of resins that go into the thermosetting and alloy adhesive classes are noted for high strength, creep resistance, and resistance to environments such as heat, moisture, solvents, and oils. Then-physical properties are weU suited for structural-adhesive applications. 

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