Micromechanics of toughening in polymeric composites

The macroscopic tensile toughness of glassy homo-polymers is often limited due to either localized crazing followed by failure [e.g., polymethyl-methacrylate (PMMA), polystyrene (PS)], or cavitation-induced brittle failure under high triaxiality [e.g., polycarbonate (PC)]. Judicious choice of polymer composites alleviates the above concerns by spreading the inelastic deformation and damage throughout the material, thereby increasing the macroscopic toughness. This thesis focuses on the micro- and macro-mechanics of two polymer composite systems - ductile/brittle PC/PMMA microlaminates and rubber-toughened PS. Ductile/brittle microlaminates are comprised of alternating layers of ductile polymer (e.g., PC) that inelastically deform by shear yielding, and brittle polymer (e.g., SAN, PMMA) that undergo crazing in tension. The layer thicknesses are typically in the sub-micron to tens of micron range. We have modeled the deformation and axial tensile toughness of PC/PMMA micro-laminates. Experiments indicate that the macroscopic ductility of ductile/brittle polymeric laminates depends on several factors such as the thickness of the brittle and ductile layers, the volume fraction of the ductile component, as well as strain rate.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Sharma, Rajdeep

Advisor dc:contributor.advisor

• Mary C. Boyce and Simona Socrate.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/38561

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/38561