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In order to predict the storage life of a certain type of HTPB (hydroyl-terminated polybutadiene) coating at 25 °C and analyze the influence of pre-strain on the storage life, the accelerated aging tests of HTPB coating at 40 °C, 50 °C, 60 °C, 70 °C with the pre-strain of 0%, 3%, 6%, 9%, respectively were carried out. The variation regularity of the change of crosslinking density was analyzed and the aging model of HTPB coating under pre-strained thermally-accelerated aging was proposed. The storage life of HTPB coating at 25 °C was estimated by using the Berthelot equation as the end point of the aging life with a 30% decrease in maximum elongation. The results showed that the change of crosslinking density of HTPB coating increased with the increase of aging temperature and aging time, and decreased with the increase of pre-strain. Under 0% pre-strain, the relationship between the change of crosslinking density of HTPB coating and the aging time can be described by the logarithmic model with the confidence probability greater than 99%.The stress relaxation phenomenon existed under 3%, 6% and 9% pre-strained aging. The aging model considering chemical aging and pre-strain was established with the confidence probability greater than 90%. The storage life of HTPB coating was 15.2935 years at 25 °C under 0% pre-strain, which was reduced by 13.9007%, 75.6949% and 89.7859% under 3%, 6% and 9% pre-strain, respectively. The existence of pre-strain has a serious impact on the storage life of HTPB coating, therefore, the pre-strain should be avoided as much as possible during the actual storage.
Yong-Qiang Du; Jian Zheng; Gui-Bo Yu. Storage life prediction under pre-strained thermally-accelerated aging of HTPB coating using the change of crosslinking density. Defence Technology 2020, 1 .
AMA StyleYong-Qiang Du, Jian Zheng, Gui-Bo Yu. Storage life prediction under pre-strained thermally-accelerated aging of HTPB coating using the change of crosslinking density. Defence Technology. 2020; ():1.
Chicago/Turabian StyleYong-Qiang Du; Jian Zheng; Gui-Bo Yu. 2020. "Storage life prediction under pre-strained thermally-accelerated aging of HTPB coating using the change of crosslinking density." Defence Technology , no. : 1.
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.
Yong-Qiang Du; Jian Zheng; Gui-Bo Yu; Jian-Zhuang Zhi. Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging. Defence Technology 2020, 17, 821 -828.
AMA StyleYong-Qiang Du, Jian Zheng, Gui-Bo Yu, Jian-Zhuang Zhi. Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging. Defence Technology. 2020; 17 (3):821-828.
Chicago/Turabian StyleYong-Qiang Du; Jian Zheng; Gui-Bo Yu; Jian-Zhuang Zhi. 2020. "Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging." Defence Technology 17, no. 3: 821-828.
Hydroxyl terminated polybutadiene (HTPB) coating is widely used in a solid rocket motor, but an aging phenomenon exists during long-term storage, which causes irreversible damage to the performance of this HTPB coating. In order to study the effect of aging on the dynamic mechanical properties of the HTPB coating, the thermally-accelerated aging test was carried out. The variation of maximum elongation and crosslinking density with aging time was obtained, and a good linear relationship between maximum elongation and crosslinking density was found by correlation analysis. The changing regularity of dynamic mechanical properties with aging time was analyzed. It was found that with the increase of aging time, Tg of HTPB coating increased, Tα, tan β and tan α decreased, and the functional relationships between the loss factor parameters and crosslinking density were constructed. The storage modulus and loss modulus of HTPB coating increased with the increase of aging time, and decreased with the increase of pre-strain. The aging enhanced the Payne effect of HTPB coating, while the pre-strain had a weakening effect. In view of the Payne effect of HTPB coating, the crosslinking density was introduced into Kraus model as aging evaluation parameter, and the crosslinking density modified models with and without pre-strain were established. The proposed models can effectively solve the problem that the Kraus model has a poor fitting effect under the condition of small strain (generally less than 1%) and on the loss modulus, which have improved the correlations between the fitting results and the test results.
Yongqiang Du; Jian Zheng; Guibo Yu. Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect. Polymers 2020, 12, 403 .
AMA StyleYongqiang Du, Jian Zheng, Guibo Yu. Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect. Polymers. 2020; 12 (2):403.
Chicago/Turabian StyleYongqiang Du; Jian Zheng; Guibo Yu. 2020. "Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect." Polymers 12, no. 2: 403.
In order to study the aging property of HTPB propellant in storage and the effect of antioxidant on the storage life of propellant, accelerated aging tests were carried out for two types of propellant. A non-linear aging model was introduced into the classical Arrhenius equation, and the starting point of aging was modified. With the maximum elongation as the evaluation parameter, the storage life at 25 °C is 9.6 years with the critical value is 20%, and the storage life is 17.5 years with the critical value is 15%. By controlling the content of antioxidant in propellant, the formula of type I propellant was modified, and the life of propellant after modification was predicted. The storage life is 12.4 years at 25 °C with the critical value is 20%, and the storage life of propellant is 21.3 years when the critical value is 15%. It was proved that the storage life of propellant could be effectively improved by controlling the content of antioxidant.
Du Yongqiang; Zheng Jian; Zhi Jianzhuang; Tu Xin. Effect of Antioxidant on Storage Performance and Life Prediction of HTPB Propellant. IOP Conference Series: Materials Science and Engineering 2019, 538, 012047 .
AMA StyleDu Yongqiang, Zheng Jian, Zhi Jianzhuang, Tu Xin. Effect of Antioxidant on Storage Performance and Life Prediction of HTPB Propellant. IOP Conference Series: Materials Science and Engineering. 2019; 538 (1):012047.
Chicago/Turabian StyleDu Yongqiang; Zheng Jian; Zhi Jianzhuang; Tu Xin. 2019. "Effect of Antioxidant on Storage Performance and Life Prediction of HTPB Propellant." IOP Conference Series: Materials Science and Engineering 538, no. 1: 012047.