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Description
Title: | Crack Healing in Polymers (Fracture, Reptation, Tack) |
Author(s): | O'Connor, Kevin Michael |
Department / Program: | Metallurgy and Mining Engineering |
Discipline: | Metallurgical Engineering |
Degree Granting Institution: | University of Illinois at Urbana-Champaign |
Degree: | Ph.D. |
Genre: | Dissertation |
Subject(s): | Engineering, Materials Science |
Abstract: | The mechanical property development associated with the healing of polymer-polymer interfaces was studied using theoretical and experimental approaches. The healing of crazes in atactic polystyrene (PS) and microvoids in styrene-isoprene-styrene block copolymers was described phenomenologically, from dark-field optical microscopy and light transmission measurements. For the healing of bulk polymer surfaces, molecular-level models were coupled with experiments to investigate the effects of healing time t, temperature T, and molecular weight M. The reptation theory of self-diffusion in entangled polymers was used to describe chain motions and interpenetration at a polymer-polymer interface. Various dynamic quantities, including the average segment interpenetration depth (gamma), were related to the fracture strength (sigma) and fracture energy E through microscopic fracture criteria. For a polybutadiene elastomer, (sigma)(,o) is the surface wetting contribution, K is a constant, and t(,(INFIN)) is the time to achieve full healing. A reanalysis of literature data for natural rubber showed (sigma) (TURN) M('- 1/4) for a constant t 2.5 x 10('5). The M(' 1/2) behavior is consistent with chain pullout, and M('o) is consistent with chain fracture. |
Issue Date: | 1984 |
Type: | Text |
Description: | 190 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984. |
URI: | http://hdl.handle.net/2142/71812 |
Other Identifier(s): | (UMI)AAI8422787 |
Date Available in IDEALS: | 2014-12-16 |
Date Deposited: | 1984 |
This item appears in the following Collection(s)
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Dissertations and Theses - Metallurgy and Mining Engineering
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Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois