of moisture too little moisture is inadequate for the purpose of serving as an expansion agent in subsequent processing on the other hand too great a moisture content will cause the product to come apart in the subsequent rapid expansion step after the 34 standard pressboard 34 has recovered the moisture it may be placed in a rapid opening press and is rapidly e g within one minute brought up to a temperature of 200 u00b0 c to 315 u00b0 c preferably 260 u00b0 c to 290 u00b0 c about the temperature of the press and to a pressure of from 2070 kpa to 10 340 kpa 300 to 1500 psig preferably from 4830 to 10 340 kpa 700 to 1500 psig constraint is then instantaneously removed within one second by opening the press to allow the expanding pressboard to occupy a predetermined volume whereby the density of the pressboard is less than 0 45 g cc the product has a smooth continuous surface and a density of from 0 14 to 0 45 g cc it is strong having a tensile strength greater than 9650 kpa 1400 psi preferred products of the invention made from p m phenylene isophthalamide fibrids and p m phenylene isophthalamide floc have a crystallinity as shown by heat absorbency at the glass transition temperature tg of less than 0 8 joule g density is measured by cutting the board into a rectangular sample at least 10 cm by 10 cm making sure that the corners are cut square so that.