Question

* 56. High pressure foaming usually results in product that is: A. Flexible and closed cell B. Rigid and open cell C. Both rigid and flexible but having open cell D. Both rigid and flexible but having closed cell #57. The foam insulation found in large diameter coaxial cable is created by: A. Mechanical foaming. B. Chemical foaming. C. Physical foaming. D. Hollow glass sphere foaming.

Answer 1

56) C

High Pressure Foaming Machines. These High-Pressure Machines are widely used for various PU Foaming application like Rigid PU foaming application and Flexible PU foaming application.The compact open frame construction makes this machine easier to operate.

57) B

method for manufacturing a foam coaxial cable, which includes a central conductor, an insulation layer formed out of the central conductor, a shield formed out of the insulation layer, and a jacket formed on an outer circumference of the shield, the method comprising:

(A) co-extruding a polyolefin resin in a melted state on an outer circumference of the central conductor to form an inner skin layer coated as a thin film thereon with a thickness between 0.01 to 0.1 mm;

(B) co-extruding a polyethylene resin on an outer circumference of the inner skin layer to form an insulation layer having a thickness between 5 to 15 mm and uniformly including a plurality of foam cells with a size between 100 to 1000 μm on the basis of an average diameter of long and short axes thereof;

(C) co-extruding a polymer resin, which is made of the same material as the insulation layer, on an outer circumference of the insulation layer to form an outer skin layer coated as a thin film thereon with a thickness between 0.01 to 0.5 mm; and

(D) forming the shield and the jacket on an outer circumference of the outer skin layer.