Accession Number:

ADA164130

Title:

Crack Healing in Polymers.

Descriptive Note:

Final rept. 18 Apr 83-30 Sep 85,

Corporate Author:

ILLINOIS UNIV AT URBANA DEPT OF METALLURGY AND MINING ENGINEERING

Personal Author(s):

Report Date:

1985-12-20

Pagination or Media Count:

17.0

Abstract:

When two similar polymers contact in the melt to form a polymer-polymer interface, interdiffusion of random-coil chains occurs. For this case, we determine a set of properties, H, as a function of time, t, and molecular weight, M. They include the number of chains, n, number of bridges, p, average monomer interpenetration depth, X, the total monomer depth, X sub o, the center of mass diffusion, X sub cm, the average contour interpenetration length, l, the total contour length, L sub O, and the average bridge length, l sub p. The time dependent, Ht, and equilibrium solutions, H infinity, are summarized. When two similar amorphous polymers make good contact to form a polymer-polymer interface, we ask how strength develops as a function of contact time, t, and molecular weight, M, of the polymers. Fracture stress, sigma, shear stress tau, critical fracture energy, G sub IC, and fatigue crack propagation rates, dadN, are determined as functions of t and M. Solutions to this problem have application to polymer processing, internal weld-lines, coatings, welding, lamination and the physics of fracture mechanics. The problem is divided into three parts. The first part consists of determining a set of molecular properties for the interface, Ht. The second part relates the properties of the interface to the mechanical properties via a set of deformation mechanisms involving chain disentanglement and bond rupture. The third part of the solution consists of determining the fracture mechanics of a crack propagating through an interface using solutions of the first two parts.

Subject Categories:

  • Plastics
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE