Sprut-5M adhesive

The Sprut-5M adhesive consists of unsaturated polyester resin 100 parts hy weight, ATG-M 80 parts (a mixture of 50 parts of macrodiisocyanate md 30 parts of ATG), polymerization initiator (MEKP(O)) 2 parts. Usually lwt% of CN is integrated additionally into the adhesive base. Sprut-5M can be produced using various polyester resins, but the most applicable one is the adhesive based on PM-I resin owing to its availability and low cost. For this reason we will consider the properties of the adhesive based mainly on this resin although it has adhesion strength 20—40% lower than that of adhesives based on PN-11, NPS 609-21M, and other resins, especially when cementing in water. 

Figure 3.1 presents the maximum stress surfaces when St3 steel is cemented with the Sprut-5M adhesive and the polyester and poly-... 

We investigated the effect on the adhesion strength of shear stresses applied to the adhesive interlayer MDI as a component of Sprut-5M adhesive. An equimolar quantity of butylene glycol was added to MDI to cure it. The shear stresses were created by the torsion of one dolly of standard size relative to another in a special device the adhesive was placed between the dollies. On reaching the prescribed shear stress (due to the increase of the adhesive viscosity) the torsion of the dolly... 

Properties of Sprut-5M adhesive-based reinforced coatings... 

Thus, Sprut-5M adhesive-based reinforced coatings allow an increase in the strength of the metal, mainly under the conditions in which the load on the specimen exceeds the elastic limit of the steel. 

These are frequently the condtions under which structures operate that are weakened by intensive metal corrosion—pipelines, oil tanks, ships. Sprut-5M adhesive is successfully used for strengthening... 

Let us consider some mechanical properties of biplates. These are steel plates onto which glass-reinforced plastics are molded, with Sprut-5M adhesive used as a binder. The types of mechanical load selected were those that were encountered in the course of the coating operation. 

Taking Sprut-5M adhesive as an example, consider the modulus of elasticity of the polymer in the adhesive layer in terms of the distance... 

Determining thermal internal stresses. Experimentally, the stress with a particular temperature change is determined by the deflection of the free end of the cemented three-layer plate fixed as a cantilever. The deflection of the plate end was determined by means of a projection optical system. Figure 4.3 displays the distribution of the thermal internal stresses in a Sprut-5M adhesive-bonded joint for temperature change from 20 to 42°C. Plates made of IKhlSNlOT steel 0.07 mm thick and aluminum foil 0.02 mm thick were used as substrates. It is evident that the internal stresses are characterized by maximum values on the interfaces. 

Let us consider how to determine experimentally the shrinkage internal stresses. An optical system similar to that descrihed in Section 4.2.1 was used to determine the displacement of the free end of the cantilever-fixed adhesive-honded plate. Plates made of aluminum foil 5 X 10 m thick E = 0.7 x 10 MPa) and of steel 10 x 10 m thick (E = 2 X 10 MPa), hoth with areas of 1 x 10 cm, served as substrates. Sprut-5M adhesive was used to cement the plates. The shrinkage internal stresses were determined at 293 K 2 days after the specimens were prepared. 

It is evident that with temperature elevation from 293 to 314 K the modulus of elasticity of the Sprut-5M adhesive changes insignificantly, demonstrating the apphcahiUty of the method of temperature stresses. 

Thus, one can identify at least three factors that increase the longterm strength of Sprut-5M adhesive at the stage of formation of the polyurethane network but which have no further effect after the adhesive cures completely. Actually, in this state of the adhesive there is no indication of the structure that is observed with the orientation of the molecular chains there is an abrupt reduction of the opportunity for macroradicals to recombine and for the submicrocracks to be filled. At this stage of curing, despite some decrease of the long-term strength under a load of 50% of the fracture load, the Sprut-5M adhesive has much better resistance to the effect of constant loads than does the polyester adhesive (see Fig. 3.2, curve 1 (after 102 days) and curve 4). 

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