Abstract 4‐Vinylbenzene sulfonic acid sodium salt (VB) – Acrylamide (Aam) homopolymerization and copolymerization reactions with various feed ratios were performed in water at 60 °C. All reactions were monitored online, by an Automatic Continuous Online Monitoring of Polymerization (ACOMP) system. The concentrations of the two comonomers in their monomeric form, as well as their concentrations incorporated into polymer, were obtained from the monitored data. It was seen that Aam homopolymerization was faster than VB and both homopolymerization rates were higher than copolymerization rates at any combination. In the reactions with 1.5%, 5% and 10% (mol) VB, VB was completely depleted and further reaction was Aam homopolymerization. In the copolymerizations with 5 to 50% initial VB content, the plots of VB fraction in the remaining monomer mixture versus conversion exhibited a corner at 10–30% conversion. This corner showed that the behavior of the reaction changed abruptly at this point. In the first stage of the reactions, the composition was seen to be almost constant with almost no composition drift whereas in the second part, the VB fraction decreased monotonically. Monomer reactivity ratios (MRR) were calculated by error in variables (EVM) method. Since the reactions gave two distinguishable regions, the reaction part before and after the corner were evaluated separately. Therefore, the monomer reactivity ratios were found as r Aam = 0.34 ± 0.07, r VB = 0.40 ± 0.21 for the part before and r Aam = 0.2 ± 0.04, r VB = 9.0 ± 0.8 for the part after the corner.
Suda cozunen dogal ve sentetik polimerler gundelik hayatimizda genis yer tutar. Polielektrolit denilen ve suda cozundugunde yuklu gruplar veren polimerler de bu grubun onemli bir uyesidir. Polielektrolitler ya yuklu monomerin polimerizasyonu yada yuklu ve yuksuz monomerlerin kopolimerizasyonu ile elde edilebilir. Bu calismada akrilik asit (Aac) – akrilamit (Aam) kopolimerizasyonu, pH 5 ve pH 2’de gerceklestirildi ve tum reaksiyonlar ACOMP (Automatic Continuous Online Monitoring of Polymerizatian – Polimerizasyon Reaksiyonlarinin Bilgisayarla Surekli Izlenmesi) sistemi ile surekli olarak izlendi. Kopolimerizasyon suresince her iki monomerin polimere giren miktarlari ve monomer haldeki konsantrasyonlari ultraviyole spektrofotometre (UV) dedektoru ile belirlendi. Yapilan kinetik incelemeler her iki pH’taki reaksiyonlarin monomere gore 1’inci dereceden sapma gosterdigini fakat 1.25’inci ve 1.5’uncu derece kinetige uydugunu gosterdi. Surekli izleme metodunun sagladigi genis capli veri alma imkani sayesinde pH 5’te gerceklestirilen tum reaksiyonlarda, akrilamidin daha aktif oldugu dolayisiyla daha hizli tukendigi ve akrilik asitin aktivitesinin ise iyonlasma ve elektrostatik etkilesimlerden dolayi daha az oldugu belirlendi. pH 2’deki reaksiyonlarda ise tam tersine akrilamit protonlanma nedeniyle aktivitesini kaybederken akrilik asitin bu pH’da daha aktif oldugu gozlendi. Reaksiyon kinetigindeki bu farklilasmanin sebebi kafes etkisi acisindan tartisildi. Ayni zamanda ACOMP sisteminde yer alan dedektorlerden biri olan isik sacilmasi dedektoru vasitasiyla pH 5 ve pH 2’de yapilan tum deneylerdeki molekul agirligi degisimi reaksiyon suresince izlendi. Anahtar Kelimeler: Polielektrolitler, suda cozunen polimerler, kopolimerizasyon, reaksiyon kinetigi, molekul agirligi, surekli izleme.
Summary: Ultrasound applications provide additional ways in polymerization and copolymerization synthesis. Ultrasonic depolymerization has wide applications in industry and is also used in copolymer synthesis. Another application of depolymerization is investigating the termination mechanism and finding the combination/disproportionation ratio for various monomer-polymer systems. In this work ultrasonic depolymerization of polyvinyl pyrrolidone and polyacrylamide were investigated. Sonications were monitored continuously by the ACOMP (Automatic continuous monitoring of polymerization) system, which provides viscosity, light scattering, ultraviolet and refractive index measurements continuously. Depolymerizations were performed in the absence and presence of a radical scavenger and disproportionation/combination ratios were discussed for each system.
