Adhesive Pour No. 1 



Adhesive Pour No. 2 



Adhesive Pour No. 3 



!■•■•■ •■■•■•■■■ ■•! Fresh, liquid adhesive 

 y//////////\ old, solid adhesive 



Figure 42. Procedure for casting of 

 self-polymerizing joints 

 in acrylic plastic capsules. 



In view of the many 

 advantages that such a bonding 

 technique possesses for fabrica- 

 tion of large-scale acrylic plastic 

 capsules, it was decided to 

 evaluate this technique first 

 on small-scale capsules and on 

 joint-test specimens simulating 

 the joint dimensions of the 66- 

 inch capsule. Four cast-in-place 

 adhesives were investigated: 

 epoxy, polyester, PS-18 acrylic 

 cement, and PS-30 acrylic cement. 

 The epoxy and polyester adhe- 

 sives were almost immediately 

 discarded as the tensile strength 

 of a joint between acrylic plastic 

 members filled with these adhe- 

 sives was less than 1 ,500 psi for 

 epoxy and 1,000 psi for polyester. 

 Although the compressive strength 

 of these two adhesives was indis- 

 tinguishable from that of the 

 acrylic plastic parent material, the 

 low tensile strength just made 

 these adhesives noncompetitive 

 with the PS-18 and PS-30 acrylic 

 cements. When 2.5-inch-wide 

 acrylic plastic blocks were bonded 

 with acrylic cement in 0.125-inch- 

 wide joints, it was found that the 

 tensile strength for PS-18 was 

 consistently higher than 5,000 

 psi, while for PS-30 it was higher 

 than 4,000 psi (Table 3). Com- 

 pressive strength of these joints 

 was found to be of approximately 

 the same magnitude as that of the 

 parent acrylic plastic material, but 

 their deformation under load was 

 somewhat higher. 



69 



