| Abstract: | Divinylbenzene (DVB) shells with a density of about 100 mg/cc were produced using a dual‐thermal initiator system. New high‐gain designs for direct‐drive ignition at the National Ignition Facility and the OMEGA laser facility at the Laboratory for Laser Energetics require low‐density foam shells such as these. Previous research using a single initiator system produced fragile DVB shells that cracked or imploded during the fabrication process. The dual‐initiator DVB system used in the present study enabled the shells to be robust enough to produce a high yield of intact shells. The two thermal initiators used were azobisisobutyronitrile (AIBN) and another azo‐type initiator, V‐70. The DVB shells were 800–3500 μm in diameter, with shell wall thickness 7%–10% of the diameter. Because the foam shells were porous, a full‐density permeation barrier of poly(vinyl phenol) was developed and deposited on the shells using two techniques to enable the shells to retain gas. The initial results show that the permeation barrier was pinhole free and could hold the gas in a gas‐filled shell. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2523–2529, 2006 |
