Abstract Polyamide membranes of desired thickness are prepared by dissolving polyamide in HCl, admixing paraformaldehyde and then zinc chloride to produce a viscous paste, forming expanded gelatinous material by treatment with formaldehyde, curing this material and applying tensile stress thereto. Rigid, water insoluble, polyamide foam material is prepared by treating polyamide with concentrated solution of zinc chloride in HCl to make a gum-like solid and supernatant liquid, admixing 1,3,5trioxane and the gum-like solid to make a homogeneous, light, and flowable paste which is then cured in a suitable mold at atmospheric conditions, preferably in the presence of weakly acidic water. The membranes are useful, e.g., for bandages and the nylon foam is useful, e.g., as a construction material, for trays, containers, etc.
The process of claim 1 in which the polyamide to hydrochloric acid ratio is between about 0.1:1 and about 1:1.
Claim 2
Dependent Claim
22 words
The process of claim 1 in which the ratio of solid formaldehyde-containing material to polyamide is between about 0.1:1 and about 0.5:1.
Claim 3
Dependent Claim
18 words
The process of claim 1 in which the zinc chloride to polyamide ratio is at least about 0.1:1.
Claim 4
Dependent Claim
30 words
The process of claim 1 in which said liquid formaldehyde is added to said viscous paste slowly with agitation over a period of time to saturate the resulting gelatinous material.
Claim 5
Dependent Claim
29 words
The process of claim 1 in which said gelatinous material is cured under essentially atmospheric conditions for a period of time between about 1/2 and about 1 1/2 hours.
Claim 6
Dependent Claim
23 words
The process of claim 1 in which residual chemicals remaining in said membrane are extracted therefrom by leaching thereof in relatively cold water.
Claim 7
Dependent Claim
92 words
A process of preparing a rigid water insoluble polyamide foam which comprises: admixing a crystalline linear and long chain high molecular weight polyamide and a concentrated solution of zinc chloride in hydrochloric acid to form a gum-like solid material and a supernatant liquid, admixing solid formaldehyde-containing material selected from the group consisting of 1, 3, 5 trioxane and paraformaldehyde and said gum-like solid material to form a homogeneous, light and flowable paste, curing said paste in a suitable molding zone thereby forming rigid, water insoluble, polyamide foam of desired shape and size.
Claim 8
Dependent Claim
24 words
The process of claim 8 in which said molding is maintained under essentially atmospheric conditions, and said paste is maintained under weakly acidic water.