Model Pom-Pom Structure

1. Materials World Network: Molecular Engineering of Polymers for Processing Performance and PropertiesDonald G. Baird, Virginia Tech, DMR 0602196 Goal: Design polymer molecules for processing performance by incorporating controlled long chain branching(LCB). Approach: 1) Use molecular theory for branched polymers coupled with shear and uniaxial extensional measurements to char- acterize well-controlled commercial HDPE samples; 2) Synthesize model branched polystyrenes with known branching architectures to match the rheology of the HDPE systems; 3) Carry out film casting studies on the well defined HDPE materials to determine performance as a function of molecular structure. Figure . Fit of molecular theory to extensional viscosity as a function of time for a branched HDPE sample at extension rates of 0.1 s-1 and 1 s-1 Table: Differential pom-pom equation parameters for the HDPE sample showing branching distribution. Model Pom-Pom Structure

2. Materials World Network: Molecular Engineering of Polymers for Processing Performance and PropertiesDonald G. Baird, Virginia Tech, DMR 0602196 • Education: One PhD(Chris McGrady) and one undergraduate student (G. Hughes) and one post-doctoral(Xiang Yu) are supported by this grant. An industrial grant provides support for another PhD student(C. Seay). • Collaborative Efforts: This is a collaborative effort between two U.S. and five U.K. universities. Exchanges of students between the universities are occurring on a regular basis • Outreach: knowledge developed in this program is being incorporated into a short course given to companies. Six presen- tations including two invited ones have been given at technical meetings over the last 12 months involving this work. Film casting studies carried out with the help of a REU summer student, M. Parker, Univ. Colorado