Effects of Toluene Diisocyanate`s Chemical Structure on Polyurethane`s a Mechanical Properties for Propellant

Toluene diisocyanate (TDI) is a curing agent that is used by LAPAN in developing composite solid
propellant. TDI`s characteristics, such as %NCO, %2,4-TDI and %2,6-TDI can change during storage and depend
on the availability of TDI`s specifications that are produced by its manufacturer. This changes can lead to differences
in the characteristics of polyurethane that composes rocket propellant. Research about the effects of TDI`s
characteristics changes on polyurethane`s characteristics are needed as a direction to invent a new and better HTPB
/ TDI mass ratio composition for propellant`s formula. In this research, viscosity, rate of increasing of viscosity, %
elasticity and tensile strength of “polyurethane A” (Hydroxy Terminated Polybutadiene ( HTPB ) 2013 + TDI 2011
contains 2,4-TDI/2,6-TDI 58.4 : 41.6 ) and “polyurethane B” ( HTPB 2013 + TDI 2013 contains 2,4-TDI/2,6-TDI
42.2 : 57.8 ) that its HTPB / TDI mass ratio were 11:1, 12:1, 13:1, 14:1, 15:1 and 16:1, were measured. The
correlation`s types and levels on the graphs of NCO / OH ratio versus viscosity, rate of increasing of viscosity, %
elasticity and tensile strength were determined by using Microsoft Excel. TDI isomer content`s influences to those
polyurethane`s properties were analysed. It is discovered that higher 2,4-TDI content increases the level of positive
correlation between NCO / OH ratio and polyurethane`s viscosity and rate of increasing of viscosity, because of its
isocyanate group`s reactivity. While, higher 2,6-TDI content increases the level of positive correlation between NCO
/ OH ratio and polyurethane`s tensile strength because of its symmetry chemical structure. But, the differences in
TDI 2011 and 2013`s isomer contents only causes a few difference in the level of negative correlation between NCO
/ OH ratio and polyurethane`s % elasticity.