High fracture toughness and high modules silicone resins

Rigid silicone resins, generally referred to as polyalkylsilsesquioxanes, are an important class of hybrid thermosetting polymers with both inorganic and organic characteristics. They have superior thermal stability, heat resistance, fire resistance, and still can be easily processed. Silicone resins recently have attracted much interest as low dielectric constant materials replacing silicon dioxide as interlevel dielectrics. Unfortunately, poor mechanical properties, such as brittleness and low strength, limit their broader acceptance and applications. Efforts to toughen them date back to the 1970's, but little success has been achieved until now. Conventional polymer toughening techniques, such as incorporating second phase particles directly into the resins, typically do not work. Neither does decreasing the crosslink density of the resin network, which can compromise modulus and other properties. High fracture toughness and modulus addition cure rigid silicone resins are obtained in this study by a combination of intrinsic toughening and extrinsic toughening techniques. The addition cure silicone resin comprises two components: polyphenylsilsesquioxane oligomers containing silicon vinyls and low molecular weight silane crosslinkers containing silicone hydrides. The resin is cured by hydrosilylation between the two. Intrinsic toughening improves the plasticity and rigidity of the resin by choices of crosslinkers and polyphenylsilsesquioxane oligomers. The characteristics of molecular structure of the crosslinker and polyphenylsilsesquioxane oligomers that contribute to high fracture toughness and modulus are identified.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2000

Author dc:creator

• Li, Zhongtao, 1971-

Advisor dc:contributor.advisor

• Frederick J. McGarry.

• Materials Science and 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/1721.1/8301

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8301