Işıl Acar

Modification of Waste Poly(Ethylene Terephthalate) (PET) by Using Poly(L-Lactic Acid) (PLA) and Hydrolytic Stability

ABSTRACT The purpose of this study is the preparation of hydrolytically degradable copolymers of waste poly(ethylene terephthalate) (PET). To achieve this, we modified PET by using biodegradable poly(lactic acid) (PLA). Modification reactions were carried out in o-nitrophenol as solvent at 140 and 170°C for 8, 16, and 24 h in the presence of dibutil tin oxide (DBTO) as catalyst. The amount of the total polymers (PLA and PET) in the reaction mixture was 30% by weight, and the weight ratios of PLA/PET were 10/90, 50/50, and 90/10. These modified products were characterized by Fourier transform infrared spectrometer (FTIR), differential scanning calorimeter (DSC) as well as by hydrolytic degradation determinations. Hydrolytic degradations of the products were determined gravimetrically. Disc-shaped samples were placed in tubes containing phosphate buffer solution of pH 7.2 and kept in a water bath at 60°C for 28 days. The weight loss of the products after hydrolytic degradation ranged from 1.25% to 48.75% after 28 days.

Synthesis of Zn(II) Ion-Imprinted Polymeric Adsorbent for Selective Removal of Zinc from Aqueous Solutions

In this study, Zn(II)-imprinted polymer microbeads were synthesized for selective removal of Zn(II) from aqueous solutions. The microbeads were prepared using methacrylic acid and 1,4-vinyl pyrrolidone as functional monomers, zinc(II)acetate as zinc salt, ethylene glycol dimethacyrlate as a cross-linking agent, azo bisisobutyronitrile as an initiator and hydroxyethyl cellulose as surfactant. The non-imprinted polymer was also prepared for comparison, except without use of the Zn(II) salt. To determine the selectivity of Zn(II)-IIP beads, competitive adsorption experiments were investigated. According to the adsorption capacity values of the microbeads, Zn(II)-IIP beads show good selectivity for the target ion.

Study on adsorption, regeneration, and reuse of crosslinked chitosan graft copolymers for Cu(II) ion removal from aqueous solutions

AbstractThis study deals with the adsorption, regeneration, and reuse of chitosan-graft-itaconic acid and chitosan-graft-crotonic acid beads for Cu(II) ion removal from aqueous solutions. For this aim, adsorption capacities, adsorption kinetics, and adsorption isotherms of these crosslinked chitosan-graft-copolymeric beads were investigated in detail. The maximum adsorption capacities of chitosan-graft-itaconic acid and chitosan-graft-crotonic acid beads were found to be 0.31 and 0.25 mmol/g, respectively. In addition, it was found that the pseudo-second-order kinetic model is more suitable than pseudo-first-order model for the adsorption of Cu(II) ions onto the beads according to adsorption kinetics data. Adsorption isotherm data were evaluated using Freundlich, Langmuir, Brauner–Emmet–Teller, Dubinin–Radushkevich and Temkin isotherm models. The results revealed that the adsorption of Cu(II) ions onto the beads fits very well Freundlich isotherm model. Then, the beads were regenerated with an acid soluti...

Effects of organo clay on film properties of alkyd‐phenol formaldehyde resins

Purpose – In this study, organo clay modified alkyd resins were synthesised and these modified alkyd resins were cured with different ratios of phenol formaldehyde resin. The purpose of this paper is to investigate the physical and chemical properties of the films and thermal behaviours of the resins.Design/methodology/approach – Alkyds formulated to have an oil content of 40 percent were prepared with phthalic anhydride (PA), glycerine (G), coconut oil fatty acid (COFA), dipropylene glycol (DPG) and organo clay. “K alkyd constant system” was used for the formulation calculations of the alkyd resins. Alkyd resins were blended with 30 percent of a phenol–formaldehyde. The films of the alkyd–phenol formaldehyde (A‐PF) resins were prepared from 60 percent solid content xylene solutions by using 50 μm applicators. After the films were cured at 150°C for 2 h in an oven, properties of the films were determined.Findings – The effect of organo clay addition on the film properties such as drying degree, hardness, ...

THERMAL OXIDATIVE DEGRADATION KINETICS OF NANOCOMPOSITE ALKYD-MELAMINE FORMALDEHYDE RESIN CONTAINING MODIFIED SILICA

□ Thermal oxidative degradation kinetics of a nanocomposite alkyd-melamine formaldehyde resin containing surface-modified silica were investigated by thermogravimetric analysis. For this goal, the surface of the silica nanoparticles was modified with glycidoxypropyl trimethoxysilane. Afterwards, a nanocomposite alkyd-melamine formaldehyde resin containing 3% (wt.) ratio of surface modified silica was prepared by an in situ polymerization method. The degradation kinetics of this resin were investigated using different methods. The activation energies of different mechanism models were determined by the Coats-Redfern method. It was concluded that the actual reaction mechanism obeyed three-dimensional diffusion compared with the values obtained from the Kissinger and Flynn-Wall-Ozawa methods.

Characterization of the thermal oxidative degradation kinetics of thermoplastics

ABSTRACT Thermal oxidative degradation kinetics of polyethylene, poly(ethylene terephthalate), and polystyrene were investigated by thermogravimetric analysis. The samples included low-density polyethylene, medium-density polyethylene, high-density polyethylene, a starch-based biodegradable thermoplastic polyester, polyethylene natural gas pipe, a poly(ethylene terephthalate) water bottle, and a polystyrene drinking cup. The kinetics were conducted under dynamic conditions at heating rates of 10, 20, 30, and 40°C min−1 between 25 and 650°C in air. The Kissinger, Flynn–Wall–Ozawa, and Coats–Redfern methods were used for investigation of degradation of these polymers. Thermal oxidative degradation of the polymers was compared. Low-density polyethylene, medium-density polyethylene, high-density polyethylene, and polyethylene pipe obeyed a diffusion mechanism for oxidative thermal degradation. The starch-based biodegradable thermoplastic polyester, polystyrene cup, and poly(ethylene terephthalate) bottle followed random nucleation, diffusion, and phase boundary-controlled reaction mechanisms, respectively.

Sodyum Akrilat Esaslı Hidrojel ve Kriyojellerin Şişme, Adsorpsiyon ve Mekanik Özelliklerinin İncelenmesi

Bu calismada, sodyum akrilat esasli hidrojel ve kriyojellerin sisme davranislari (sisme kapasitesi, denge sisme degeri ve sisme kinetigi), boyar madde (metilen mavisi) adsorpsiyonu ve mekanik ozellikleri karsilastirmali olarak incelenmistir. Kinetik paramatreler, dogrusal ve dogrusal olmayan metotlar kullanilarak belirlenmistir. Buna ek olarak, kriyojel ve hidrojel yapilarin yuzey morfolojileri, taramali elektron mikroskobu (SEM) kullanilarak karakterize edilmistir. Analizlerden elde edilen tum sonuclar karsilastirmali olarak degerlendirilmistir. In this study, swelling behavior (swelling capacity, equilibrium swelling ratio and swelling kinetics), basic dye (methylene blue) adsorption and mechanical properties of sodium acrylate based hydrogel and cryogels were comparatively investigated. Kinetic parameters were determined using linear and non-linear methods. In addition, the surface morphologies of cryogel and hydrogel structures were characterized using by Scanning Electron Microscopy (SEM). All results obtained from analyses were comparatively evaluated. Anahtar kelimeler: Hidrojel, Kriyojel, Adsorpsiyon, Sodyum akrilat, Dogrusal ve dogrusal olmayan analiz yontemleri.

Epoxy-based paints from glycolysis products of postconsumer PET bottles: synthesis, wet paint properties and film properties

Glycolysis of waste polyethylene terephthalate (PET) flakes obtained from grinding postconsumer bottles was carried out at 180–190°C, and molar ratios of PET/EG were taken as 1/6. Reaction product was extracted by hot water, and water soluble crystallizable fraction and water insoluble fraction were obtained. These fractions were characterized by hydroxyl value determination. Water soluble crystallizable fraction obtained from glycolysis product was used for synthesis of PET-based epoxy resin. Two epoxy-based paints were prepared using different amounts of PET-based epoxy resin. Wet paint properties, and chemical and physical film properties of paints containing waste PET were determined. Increasing the rate of PET-based epoxy resin in paint formulation did not have a negative effect on the wet paint properties and dry film properties of epoxy-based paints containing waste PET.