Lifetime Assessments of Weapon Organics and Polymers FY05 Annual Report

Chinn, S ; Maxwell, R ; Sawvel, A ; Madabhushi, R ; Dinh, L ; Solyom, D ; Cohenour, R

Lawrence Livermore National Laboratory

关键词: Desorption;    Calorimetry;    Adhesives;    Stress Relaxation;    Binders;   

DOI  :  10.2172/920489
RP-ID  :  UCRL-TR-231920
RP-ID  :  W-7405-ENG-48
RP-ID  :  920489

美国|英语

来源: UNT Digital Library

【 摘 要 】

Non-nuclear organics, while not yet regarded to be at risk, figure in a large percentage of Significant Findings Investigations. Further, early application of advanced lifetime, compatibility, and base-lining assessments for LEP replacement materials and emerging materials for the Reliable Replacement Warhead (RRW) provides data for rational material choices. This task is currently assessing the chemical and mechanical characteristics of a variety of weapon organics prioritized by the risk-consequence of material aging. The majority of effort to date has been dedicated to silicone elastomer components known to lose their load resistance with age, with additional effort dedicated to urethane adhesives. This fiscal year, we have focused on initial aging studies of UNI620-3, a candidate replacement material for DC745U, and Adiprene (LW520). Aging studies of S5455, originally scheduled for testing in FY05, were postponed until FY07. We have initiated aging studies on these materials by employing accelerated aging tests with exposure to Co-60 {gamma}-radiation and elevated temperatures and studying their mechanical properties using a variety of analytical tools including nuclear magnetic resonance (NMR), dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). Additionally, we have investigated aging signatures present in parts returned from surveillance as well as initiated long and short term stress relaxation studies for a thorough understanding of compression set occurring in silicone elastomers components. Additional investigations of aging processes in fluoropolymer binders and the combined effects of radiation and tensile set on silicone pads were performed. Finally, we have used temperature programmed desorption (TPD) studies to significantly improve the accuracy of our H{sub 2}O outgassing model in comparison with last year through the use of the isoconversion technique as well as to measure the equilibrium vapor pressure of hydrogenated DPB pellets. This report satisfies the milestones/deliverables for the L3 task 'Update chemical and mechanical aging models for cushion/pads/adhesives' and all data will be input into the L2 milestone 'Bill's token L2 milestone'.