Accession Number:

ADA409391

Title:

Thermoplastics Modified with Nanoscale Inorganic Macromers

Descriptive Note:

Technical paper

Corporate Author:

AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST

Report Date:

1998-05-26

Pagination or Media Count:

8.0

Abstract:

We have taken a unique approach to the synthesis and study of hybrid organicinorganic materials. Our method involves synthesizing nano-size inorganic Pl0R7Si8O12 clusters which contain seven inert R groups for solubility and only one functional P group for polymerization. This strategy permits the synthesis of melt processable, linear hybrid polymers containing pendent inorganic clusters and allows us to study the effect these clusters have on chain motions and polymer properties. The synthesis of norbornenyl-based polyhedral oligomeric silsesquioxane POSS macromers, their ring opening metathesis copolymerizations with varying amounts of norbornene, and analysis of the effect of the pendent POSS group is presented. The mechanical relaxation behavior and microstructure of norbornyl-POSS hybrid copolymers have been examined for their dependencies on the mole fraction of POSS-norborny monomer, as well as for potential sensitivity to the seven inert R groups present in each POSS macromer. POSS copolymerization is observed to enhance the cc-relaxation temperature, Talpha in proportion to the mole fraction of POSS-norbornyl comonomer. Interestingly, however, the magnitude of this dependence is larger for POSS-norbornyl comonomer possessing cyclohexyl groups CyPOSS than for cyclopentyl groups CpPOSS. While POSS copolymerization yields only slight enhancement of the tensile storage modulus measured near room temperature at temperatures lower than a strong mechanical relaxation Beta-relaxation near T -75 degrees C, there is a significant POSS-reinforcement of the storage modulus.

Subject Categories:

  • Polymer Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE