THE EFFECTS OF NITROGEN CONTENT, STORAGE TEMPERATURE AND AGEING ENVIRONMENT ON THE RATES OF POLYMER DEGRADATION AND STABILISER CONSUMPTION IN AGED EDC37 NITRO-PLASTICISED NITROCELLULOSE BINDER

摘要

A comprehensive study to determine how nitrocellulose (NC) nitration levels, NC storage temperatures and binder ageing environments affect the rates of NC molecular weight degradation and ethyl centralite (EC) stabiliser depletion in EDC37 nitro-plasticised binder following thermal ageing has been conducted. Isothermal accelerated ageing experiments were conducted on EDC37 binder formulations between 50-70℃ over a 7 month period. EDC37 binder is comprised of K10 plasticiser, NC polymer and EC stabiliser. For this ageing trial, three binder formulations were prepared from two grades of NC which had been stored under different conditions. The first formulation used propellant grade, imaged NC (12.10 - 12.30% nitrogen) the second formulation used lacquer grade NC (11.8% nitrogen) which had been stored at ambient temperature for 10 years and the third formulation used the same lacquer grade NC, but following storage at sub-ambient temperatures (approximately -18℃) for 10 years. Binder samples were aged under both a dry Argon environment and in air. Aged samples were periodically withdrawn and analysed; Size Exclusion Chromatography (SEC) was used to monitor NC molecular weight and High Performance Liquid Chromatography (HPLC) was used to monitor EC stabiliser concentration depletion. The rates of EC stabiliser consumption and NC degradation were measured and point-by-point kinetic analysis was used to calculate Arrhenius parameters.