Publication: Nişastanın bazı vinil ve akril monomerlerle graft kopolimerizasyonu
Abstract
Bu çalışmada, seryum (IV) amonyum nitrat ve mangan (III) asetat- pirofosfat başlatıcı sistemleri kullanılarak, nişasta ve jelatinize nişasta üzerine metil metakrilatın graft kopolimerizasyonu incelenmiştir. Deneyler iki farklı reaksiyon sıcaklığında, değişik nişasta miktarları, farklı monomer konsantrasyonları kullanılarak, asitli ve asitsiz ortamlarda, normal şartlarda ve azot atmosferinde yapılmıştır. Metil metakrilatın nişasta üzerine graft kopolimerizasyonu, literatürde ilk defa Mn(III) asetat- pirofosfat başlatıcı sistemi kullanılarak 30oC ve 45oC sıcaklıklarda, geniş bir monomer aralığında (0.1 M-2.5 M) çalışılmıştır. Normal koşullarda, asitli ve asitsiz ortamlarda yapılan deneylerin sonucunda istenilen sonuçlar elde edilemediği için, deneyler azot atmosferi ve asitli ortamda tekrarlanmıştır. Mn(III) asetat tuzu için, graft yüzdesinin monomer konsantrasyonunun artması ile azaldığı gözlenmiştir. Metil metakrilatın nişasta üzerine graft kopolimerizasyonu, Ce(IV) amonyum nitrat başlatıcısı kulanılarak 45oC sıcaklıkta, azot atmosferinde ve asitli ortamda incelenmiştir ve graft yüzdesinin monomer konsantrasyonunun artmasıyla belirli bir konsantrasyona kadar artıp bir maksimumdan geçtikten sonra tekrar azalmaya başladığı gözlenmiştir. Aynı şartlar altında nişasta miktarı arttırılarak yapılan deneylerin sonucunda da benzer sonuçlar elde edilmiştir. Nişasta 95-98 derecede jelatinize hale getirilmiştir ve başlatıcı olarak Ce(IV) amonyum nitrat tuzu kullanılarak, metil metakrilatın jelatinize nişasta üzerine graft kopolimerizasyonu incelenmiştir. Deneyler 45oC sıcaklıkta ve azot atmosferinde yapılmıştır. Deneylerin sonucunda graft yüzdesinin belirli bir konsantrasyona kadar artıp bir maksimumdan geçtikten sonra tekrar azamaya başladığı bulunmuştur. Ayrıca graftlanmış ürünlerin hidrojel özellikleri gösterebileceği dikkate alınarak, su tutma özellikleri incelenmiştir. Su tutma kapasitesi deneyleri, destile su ve % 1 lik NaOH çözeltileri içinde gerçekleştirilmiştir. Monomer konsantrasyonunun artmasıyla örneklerin su tutma kapasitelerinin azaldığı bulunmuştur. Ekstraksiyon yapılmamış homopolimer içeren ürünlerin ekstraksiyon yapılmış olan ürünlere göre daha yüksek su tutma kapasitesi gösterdikleri gözlenmiştir.
In this research, using ceric ammonium nitrate and mangane acetate- pyrophosphate initiator systems, graft copolymerization of methyl methacrylate onto starch and gelatinized starch were investigated. Experiments were carried out in acidic and non-acidic medium, under nitrogen atmosphere and at two different reaction temperatures. Various amount of starch and monomer concentration were used in these experiments. Graft copolymerization of methyl methacrylate onto starch with using Mn(III)- pyrophosphate initiator system were studied at two reaction temperatures (30oC, 45oC) and wide range of monomer concentration (0.1 M - 2.5 M). At the normally conditions and both acidic and non- acidic medium and were not able to obtain desirable results, so that experiments were repeated in nitrogen atmosphere and acidic medium for Mn(III) salt. It was observed that grafting percentage were decreased with increasing of monomer concentration. Graft copolymerization of methyl methacrylate onto starch with using Ce(IV) ammonium nitrate as initiator were investigated at 45oC under nitrogen atmosphere and in acidic medium. It was observed that grafting percentage increased at a certain monomer concentration (1.25 M) and than decreased and did not changed with increasing amount of starch. Starch were gelatinized at 95oC- 98oC. With using Ce(IV) salt as initiator, graft copolymerization of methyl methacrylate onto gelatinized starch were investigated. Experiments were made at 45oC, under nitrogen atmosphere. It was observed that gratting percentage increased at a certain monomer concentration (1.5 M) and then decreased. Additionally, water retention properties of grafted products were investigated. Water retention capacity experiments were carried out into distilled water and %1 NaOH solution. It was found that water retention capacity of samples decreased with increasing of monomer concentrations. It was observed that unextracted products (contain homopolymer) have higher water retention capacities than extracted products.
In this research, using ceric ammonium nitrate and mangane acetate- pyrophosphate initiator systems, graft copolymerization of methyl methacrylate onto starch and gelatinized starch were investigated. Experiments were carried out in acidic and non-acidic medium, under nitrogen atmosphere and at two different reaction temperatures. Various amount of starch and monomer concentration were used in these experiments. Graft copolymerization of methyl methacrylate onto starch with using Mn(III)- pyrophosphate initiator system were studied at two reaction temperatures (30oC, 45oC) and wide range of monomer concentration (0.1 M - 2.5 M). At the normally conditions and both acidic and non- acidic medium and were not able to obtain desirable results, so that experiments were repeated in nitrogen atmosphere and acidic medium for Mn(III) salt. It was observed that grafting percentage were decreased with increasing of monomer concentration. Graft copolymerization of methyl methacrylate onto starch with using Ce(IV) ammonium nitrate as initiator were investigated at 45oC under nitrogen atmosphere and in acidic medium. It was observed that grafting percentage increased at a certain monomer concentration (1.25 M) and than decreased and did not changed with increasing amount of starch. Starch were gelatinized at 95oC- 98oC. With using Ce(IV) salt as initiator, graft copolymerization of methyl methacrylate onto gelatinized starch were investigated. Experiments were made at 45oC, under nitrogen atmosphere. It was observed that gratting percentage increased at a certain monomer concentration (1.5 M) and then decreased. Additionally, water retention properties of grafted products were investigated. Water retention capacity experiments were carried out into distilled water and %1 NaOH solution. It was found that water retention capacity of samples decreased with increasing of monomer concentrations. It was observed that unextracted products (contain homopolymer) have higher water retention capacities than extracted products.