In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process, a one month thermal aging test was carried out at 70 °C with pre-strain of 0%, 3%, 6% and 9%, respectively. The low-field ¹H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages. The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging. The results showed that with the increase of aging time, the decay rate of transverse relaxation curve became faster, the transverse relaxation time decreased, the value of combined parameter qMrl increased, the proportion of crosslinking chain decreased, while the proportion of dangling chain increased. Moreover, the stress relaxation modulus increased, the crosslinking network structure of HTPB coating became denser and the degree of crosslinking increased. At the initial aging stage, the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent. With the increase of aging time, the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase. The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950, which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.

为了准确描述HTPB涂层在预应变热老化过程中的横向松弛特性和应力松弛模量，在70°C下进行了为期1个月的热老化测试，预应变为0％，3％，6％和9％分别。在不同的时效阶段对HTPB涂层进行了低场¹ H NMR和应力松弛模量测试。根据HTPB涂层在预应变老化过程中交联链和悬链的变化，提出了考虑分子链的应力松弛模型。结果表明，随着时效时间的增加，横向弛豫曲线的衰减速率变快，横向弛豫时间减小，组合参数qMrl的取值增加，交联链的比例下降，而悬链的比例增加。此外，应力松弛模量增加，HTPB涂层的交联网络结构变得更致密，交联度增加。在初始老化阶段，预应变会在一定程度上破坏HTPB涂层的交联网络结构。随着时效时间的增加，预应变的作用将逐渐减弱，时效对材料的影响将逐渐增加。考虑分子链的应力松弛模型与测试结果之间的相关性大于0.9950，可以准确地描述预应变热老化过程中HTPB涂层的应力松弛模量。