Abstract: Pseudoplastic aqueous suspensions are provided having good storage stability. These suspensions are of a prepolymer powder prepared fromA. a imide group-containing compound chosen from the group consisting of:A. a bis-imide of the formula: ##STR1## in which D represents a divalent radical which has the formula: ##STR2## wherein Y represents H, CH.sub.3 or Cl and m is equal to 0 or 1, and A represents a divalent organic radical containing 2 to 30 carbon atoms, andB. a mixture of a bis-imide of formula (I) and a mono-imide of the formula: ##STR3## in which D is as defined above and R represents a hydrogen atom or a monovalent organic radical containing 1 to 20 carbon atoms, andB. an amino compound chosen from the group consisting of:A. one or more polyamines containing 2 to 5 primary or secondary amino groups, at least one of these groups being primary,B.

Abstract: A chipboard structure is disclosed which is made substantially of 100% sawdust waste material. The chipboard has a core portion which contains the coarsest particles of the sawdust, the surface portions of the chipboard containing the finest fraction of the sawdust, intervening portions of the chipboard containing fractions which increase in size from the surface to the core portion of the chipboard. The method and apparatus involve the use of sawdust having a width and/or thickness no greater than 4.75 mm, the fractions of the sawdust having a particle size greater than 0.1 mm being sliced to increase the quantity of the fractions below 0.1 mm. Because the small particles are randomly disposed in the chipboard in directions not only parallel to the plane but also perpendicular and at an angle thereto, characteristics are obtained which are as good as chipboard produced from conventional materials other than sawdust.