Because of the weak adhesion between the different materials, the polymer lamination using the different materials is normally brittler than the single polymer by the occurrence of delamination. Similarly in rotational molding, the two layers of polyethylene(PE) and polypropylene　(PP) could not get the enough peel strength, and are dolaminated. However, in the case of inserting the dryblended powder of PE and PP as the middle layer between PE layer and PP layer, the peel strength of the multi layer rotational molding was much improved. The peel strength was changed by the density of PE in the middle layer. We observed the state of the middle layer in the rotational molding and the delaminated surface by scanning electron microscopy. Moreover, the mechanism of improved peel strength and the deformation capacity of PE in the middle layer were investigated and discussed.

View full abstract

Adhesion strength increases by the development of cohesive strength and interfacial adhesion. In order to evaluate the relative contribution ratio of those two factors, the tack of acrylic block copolymer was measured using a probe tack tester. For this purpose, three model adhesives were prepared: polymethylmethacrylate-block-polybutylacrylate-block-polymethylmethacrylate triblock(A), polymethylmethacrylate-block-polybutylacrylate diblock added triblock(B) and polybutylacrylate oligomer added triblock (C). The contact time dependency of tack measured at room temperature washigher in the order corresponding to B≒C>A and increased gradually with a contact time. The temperature dependency of tack showed the peak of tack above room temperature, and the peak ternperature was higher in the order corresponding to A>B>C. The tensile strength was higher in theorder corresponding to A>B≒C. The molecular mobility of polybutylacrylate unit measured by a 1H nuclear magnetic resonance was higher in the order corresponding to C>B>A. From the results above, it was evaluated that the relative contribution ratio of the interfacial adhesion on the tackwas larger in the order corresponding to C>B>A.

View full abstract

The evaluation method of tensile strength for the adhesive joints subjected to impact loads under high temperature was studied experimentally. The experimental equipment which the Hopkinson bar method was applied was developed. This equipment is able to measure the adhesive strength. The static load which occurs to the adhesive layer with the weight of the lower adherend is compensated at this experimental equipment. The high temperature furnace is used for the heating of the adhesive joining part. The specimen is the adhesive tubular butt joint. The impact tensile strength was evaluated using two kinds of adherends and heat-resistant inorganic adhesives. The impact tensile strength was measured under a wide range of temperature. As a result, the impact tensile strength with the rise of the temperature decreases under high temperature. These adhesives, however, maintain the adhesive streng that 1500K. Young's moduli of the adhesive under､the high temperature were measured using the test method for elastic moduli by sonic resonance. Moreover, the specimen which was put under the high temperature was observed by the scan electron microscope. As these results, the following is estimated. The decrease of the impact tensile strength is caused by the melt of the inorganic polymer which is the matrix of the adhesive.

View full abstract