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Effect of initial γ-irradiation on infrared laser ablation of poly(vinyl alcohol) studied by infrared spectroscopy
Polymer Degradation and Stability ( IF 6.3 ) Pub Date : 2020-08-12 , DOI: 10.1016/j.polymdegradstab.2020.109331
Sadulla R. Allayarov , Matthew P. Confer , David A. Dixon , Tatyana N. Rudneva , Leonid A. Kalinin , Evgenii M. Tolstopyatov , Ivan A. Frolov , Leonid F. Ivanov , Petr N. Grakovich , Oleg N. Golodkov

The effect of initial γ-irradiation of poly(vinyl alcohol) (PVA) on the kinetics of polymer ablation under CO2 laser irradiation was studied using infra-red spectroscopy. The rate of laser ablation rapidly decreases with increasing time of laser ablation up to 10 s. Initial γ-irradiation of a dose up to 100 kGy reduces the rate of the laser ablation, just like the effect of laser exposure. The number of OH and CH groups decrease in PVA both with laser irradiation and with γ-irradiation. The number of OH groups decreases more under laser irradiation. Unsaturated bonds are formed in γ–irradiated PVA on the surface of the crater formed by laser ablation of the polymer that has undergone radiolysis. Increasing the dose of initial γ-irradiation from 100 to 2300 kGy leads to an increase in the intensity of the IR bands of the unsaturated bonds. The number of IR bands in the spectra of the laser ablation crater of PVA does not change with the dose of initial γ-irradiation. A dose of radiolysis of 3500 kGy significantly changes the IR spectra of both the ablation crater and the coating formed from the ablation products. Many bands characteristic for PVA are no longer present and the intensities of bands corresponding to unsaturated bonds are increased. A computational model for loss of water and ketone formation was developed for PVA and PVA including a diol using G3(MP2). The highest activation energy barrier step in the decomposition reaction was formation of the enol species and water was shown to catalyze all decomposition steps.



中文翻译:

红外光谱研究初始γ辐照对聚乙烯醇红外激光烧蚀的影响

聚乙烯醇(PVA)的初始γ辐照对CO 2下聚合物消融动力学的影响使用红外光谱研究了激光照射。激光烧蚀速率随着激光烧蚀时间的增加而迅速降低,直至10 s。剂量高达100 kGy的初始γ辐射会降低激光烧蚀的速率,就像激光照射的效果一样。在PVA中,通过激光照射和γ照射,OH基和CH基的数量均减少。在激光照射下,OH基的数量减少更多。在不饱和键中,γ辐照的PVA会在通过激光烧蚀已发生辐射分解的聚合物而形成的火山口表面上形成。将初始γ辐射的剂量从100 kGy增加到2300 kGy,会导致不饱和键的IR波段强度增加。PVA激光烧蚀坑的光谱中的红外波段数不会随初始γ辐照剂量而变化。3500 kGy的辐射剂量可显着改变烧蚀坑和由烧蚀产物形成的涂层的红外光谱。PVA的许多特征带不再存在,对应于不饱和键的能带强度增加。利用G3(MP2),为PVA和PVA(包括二醇)开发了失水和酮形成的计算模型。分解反应中最高的活化能屏障步骤是烯醇物种的形成,并且水被证明可催化所有分解步骤。PVA的许多特征带不再存在,对应于不饱和键的能带强度增加。利用G3(MP2),为PVA和PVA(包括二醇)开发了失水和酮形成的计算模型。分解反应中最高的活化能屏障步骤是烯醇物种的形成,并且水被证明可催化所有分解步骤。PVA的许多特征带不再存在,对应于不饱和键的能带强度增加。利用G3(MP2),为PVA和PVA(包括二醇)开发了失水和酮形成的计算模型。分解反应中最高的活化能屏障步骤是烯醇物种的形成,并且水被证明可催化所有分解步骤。

更新日期:2020-08-19
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