Research On The Correlation Of Macro-micro Aging Characteristics Of HTPB Solid Propellant

HTPB propellant is a kind of widely used with the virtue of high energy,mature technology of manufacture,short curing cycle and excellent mechanical properties.The aging of HTPB is a complicated physical and chemical process.Many scholars have conducted researches and analyzes about the aging process of it,mainly focused on the macroscopic mechanical properties or changes in the chemical state of the substances.Yet which is not enough,for there is no unified systematic characterization of the aging mechanism has been drawn.The main content of this paper are as follows: experiments from different perspectives on the aging characteristics of solid propellants during storage;analysis on the correlation between macroscopic mechanical properties and changes in microscopic chemical structures;establishment of a certain relationship between macroscopic and microscopic aging characteristics.The age acceleration process of propellants has been conducted at 70°C for different days.The experimental results showed that the dynamic mechanical properties of the HTPB propellant were affected by both temperature and experiment frequency.The results showed that,as the temperature increases,the propellant completes the transition from the glassy state to the high-elasticity state;when the scanning frequency increases,the dynamic mechanical properties curve of the solid propellant move towards higher temperatures.Aging time also has a significant impact on the dynamic mechanical properties of propellants.Thus,the loss factor can be invoked as a characterization of the change in dynamic mechanical properties.The analysis on the change of microstructure of the propellants was also performed analysed during the aging process.The results showed that the peak value of the transmittance spectrum decreases at 1710 cm-1,the infrared spectrum of the C=C double bond is located,indicating that the C=C double bond in HTPB has been oxidized;a new peak is generated at 1785 cm-1,which is the the absorption peaks of carbonyl(including in aldehydes,esters,and carboxylic acids,etc).In addition,the second derivative spectrum of the infrared spectrum contributes to the discrimination of small shoulder peaks.In this paper,the grey relational analysis was used to analyze the change of macromechanical properties and the change of micro-chemical mechanism during the aging process of HTPB propellant.The alpha loss peak value of HTPB propellant and the second derivative of the infrared spectrum of propellant at the wavelength of 1785cm-1 had a strong correlation,which was the absorption peak of carbonyl.The correlation of themvalues was88.72%,and the least square method was used for linear fitting.The fitting equation was y(28)-0.01424x(10)0.402.