Publication: Gallik asit esaslı süperakışkanlaştırıcıların sentezi ve beton özelliklerine etkisinin incelenmesi
Abstract
Bu tez çalışmasıyla biyobazlı girdilerden yola çıkılarak betonda kullanılmak üzere yeni tip bir polikarboksilat süperakışkanlaştırıcı sentezi hedeflendi. Başlangıç maddesi olarak gallik asit seçildi. Öncelikle, metakrilat fonksiyonel grubuna sahip gallik asit, trifenil fosfin katalizörlüğünde gallik asit ve glisidil metakrilatın reaksiyon sonucunda sentezlendi. Daha sonraki adımda da metakrilat modifiye edilmiş gallik asidin hidroksil grupları, epiklorohidrin ile tetrabütilamonyum iyodür katalizör varlığında epoksi fonksiyonel gruplarına dönüştürüldü. Saflaştırma ve karakterizasyon adımları sonrasında epoksi ve metakrilat grupları içeren gallik asit elde edildi. Elde edilen bu monomer, sodyum vinil sülfonat ve akrilik asit monomerleri ile benzoil peroksit radikalik başlatıcısı kullanılarak serbest radikal polimerizasyonuyla hedeflenen kopolimerlerin sentezi gerçekleştirildi. Diğer bir yandan da polietilen glikol (PEG) ve maleik anhidritin p-toluen sülfonik asit katalizörlüğünde reaksiyonundan karboksil uç gruplu PEG sentezi gerçekleştirildi. Elde edilen karboksil uç gruplu-PEG ile epoksi fonksiyonel gruplarına sahip kopolimerlerin reaksiyonuyla nihai ürün olarak polikarboksilat akışkanlaştırıcı elde edildi. Sentezlenen tüm bileşiklerin yapısal ve termal karakterizasyonları Fourier Transform Infrared Spektroskopisi (FTIR), Nükleer Manyetik Rezonans (NMR), Jel Geçirgenlik Kromatografisi (GPC/ SEC), Diferansiyel Taramalı Kalorimetre (DSC) ve Termogravimetrik Analiz (TGA) kullanılarak yapıldı. Elde edilen bu biyobazlı polikarboksilat akışkanlaştırıcıların beton üzerindeki etkilerini incelemek üzere çeşitli testler yapıldı. Bunun için harç zeta potansiyeli ölçümü, yüzey gerilimi ölçümü, harç karışım denemesi ve yayılma tablası deneyleri gerçekleştirildi.
This thesis aimed to synthesize a new type of polycarboxylate superplasticizer for use in concrete, starting from bio-based inputs. Gallic acid was selected as the starting material. Initially, gallic acid with a methacrylate functional group was synthesized by reacting gallic acid and glycidyl methacrylate in the presence of a triphenylphosphine catalyst. In the subsequent step, the hydroxyl groups of methacrylate-modified gallic acid were converted into epoxy functional groups using epichlorohydrin in the presence of a tetrabutylammonium iodide catalyst. After purification and characterization steps, gallic acid containing epoxy and methacrylate groups was obtained. This monomer was then copolymerized with sodium vinyl sulfonate and acrylic acid monomers using benzoyl peroxide as a radical initiator through free radical polymerization. Additionally, polyethylene glycol (PEG) with carboxyl end groups was synthesized by reacting PEG and maleic anhydride in the presence of p-toluenesulfonic acid as a catalyst. The final product, polycarboxylate superplasticizer, was obtained by reacting the carboxyl-terminated PEG with the copolymers containing epoxy functional groups. The structural and thermal characterizations of all synthesized compounds were performed using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC/ SEC), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). Various tests were conducted to examine the effects of these bio-based polycarboxylate superplasticizers on concrete. For this purpose, zeta potential measurement, surface tension measurement, mortar mixing trials, and spread table tests were performed.
This thesis aimed to synthesize a new type of polycarboxylate superplasticizer for use in concrete, starting from bio-based inputs. Gallic acid was selected as the starting material. Initially, gallic acid with a methacrylate functional group was synthesized by reacting gallic acid and glycidyl methacrylate in the presence of a triphenylphosphine catalyst. In the subsequent step, the hydroxyl groups of methacrylate-modified gallic acid were converted into epoxy functional groups using epichlorohydrin in the presence of a tetrabutylammonium iodide catalyst. After purification and characterization steps, gallic acid containing epoxy and methacrylate groups was obtained. This monomer was then copolymerized with sodium vinyl sulfonate and acrylic acid monomers using benzoyl peroxide as a radical initiator through free radical polymerization. Additionally, polyethylene glycol (PEG) with carboxyl end groups was synthesized by reacting PEG and maleic anhydride in the presence of p-toluenesulfonic acid as a catalyst. The final product, polycarboxylate superplasticizer, was obtained by reacting the carboxyl-terminated PEG with the copolymers containing epoxy functional groups. The structural and thermal characterizations of all synthesized compounds were performed using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC/ SEC), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). Various tests were conducted to examine the effects of these bio-based polycarboxylate superplasticizers on concrete. For this purpose, zeta potential measurement, surface tension measurement, mortar mixing trials, and spread table tests were performed.