antifoulant via the organotin curing agent have also been prepared. A 

 second type of glass-reinforced epoxy laminate employing a "shell" laminate 

 concept has been fabricated. The bottom plies of this laminate were laid 

 up as in a conventional epoxy system; the remaining plies were laid up with 

 and organotin epoxy as a "shell" or outer covering over the conventional 

 spoxy system. Both types of laminates were cured at elevated temperatures. 

 Conventional polyester glass-reinforced laminate and a conventional epoxy 

 glass-reinforced laminate were fabricated by using the same technique as 

 for the organotin laminates, for comparison purposes. The flexural 

 strengths and moduli, tensile strengths and moduli, compressive strength, 

 specific gravity, and resin content were determined by ASTM methods. The 

 organotin polyester laminate exhibited only a slight decrease in strength 

 properties compared to the conventional polyester laminate (Table 11) . 



TABLE 11 - PHYSICAL PROPERTIES OF ORGANOTIN AND CONVENTIONAL LAMINATES 



Property 



Epoxy Laminates 



Polyester 



Laminates 



Organotin 



OMP 

 "Shell" 



Conven- 

 tional 



Organotin 



Conven- 

 tional 



Flexural 



56,600 



65,700 



72,200 



55,400 



63,800 



Strength, psi 













Flexural 



2.5 x 10^ 



2.8 X 10^ 



3.5 X 10^ 



2.5 X 10^ 



2.7 X 10^ 



Modulus, psi 













Tensile 



44,100 



48,200 



50,500 



43,400 



44,800 



Strength, psi 













Tensile 



2.8 X 10^ 



3.0 X 10^ 



3.3 X 10^ 



3.0 X 10^ 



3.5 X 10^ 



Modulus, psi 













Compressive 



36,900 



48,200 



55,600 



30,900 



33,000 



Strength, psi 













Resin Content, % 



38 



39 



36 



43.2 



40.0 



Specific 



1.69 



1.78 



1.82 



1.90 



1.90 



Gravity, g/m 













The organotin epoxy laminate showed a decrease in the strength properties 

 compared to the conventional epoxy laminate. However, the "shell" laminate 

 exhibited only a slight decrease in the strength properties. An oragnotin 

 epoxy laminate showed less than 1-percent water absorption after a year of 



45 



