Improvement of rheological, mechanical and interface properties of solid rocket motor liner

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2021-2-11
Aslan, Onurcan
This study aims to improvethe mechanical, rheological, and interface propertiesofthe currently used liner formulation (referred to as the standard liner) based on carbon black filled polyurethanestructure.Two types of carbon black powders (Thermax N-991 and Printex-U) were used as fillers inHydroxyl-Terminated Polybutadiene(HTPB) -Isophorone Diisocyanate(IPDI)based polyurethane liner. Three different dispersing agents (alkylammonium salt of a high molecular-weight copolymer, high molecular-weight copolymer with pigment affinic groups, and hydroxyl functional silicone modified polyacrylate) were used in this study. Alkylammonium salt of a high molecular-weight copolymerdispersing agent wasdeterminedthe most effectiveaccording to rheologicalandmechanical test results and particle size analyses. The particle size was lowered from 521 nm to 392 nm for Thermax N-991 and from 550 nm to 263 nm for Printex-Uwhen the dispersant agent (alkylammonium salt of a high molecular-weight copolymer) was used. The tensile strength and the elongation at break values of the standard polyurethane liner were 1.3 MPa and 270percent, respectively,and they were improved to 1.77 MPaand 370percent, respectively, when 10 weight percent of Printex-Uwere addedin the polyurethane liner. Furthermore, the tensile strength and the elongation at break values of the polyurethane liner were improved to1.88 MPaand410percent, respectively,with the addition of 2weight percentof alkylammonium salt of a high molecular weight copolymerdispersing agent based on the amount of carbon black. The viscosity of the carbon black filled liner formulation wasalsodecreased about two folds; thus, thepot-lifeof the polyurethane linerwas extended up to 53percent by adding the dispersing agent. Moreover, the effective dispersion of carbon black particles made thepolyurethaneliner more resistant to the plasticizer migrationat the interface.It is concluded that the use of alkylammonium salt of a high molecular weight copolymerdispersing agent improves mechanical, rheological, and interface propertiesof thepolyurethane liner containing 10weight percentof Printex-Ucarbon black.
Citation Formats
O. Aslan, “Improvement of rheological, mechanical and interface properties of solid rocket motor liner,” M.S. - Master of Science, Middle East Technical University, 2021.