Search

This article described the synthesis and characterization of new copolymer hydrogels containing two hydrophilic units-methacrylic acid (MAA) and 2-Acrylamido-2-methylpropane sulfonic acid (AMPS). The resulting hydrogels were characterized by various techniques: FTIR, Elemental analysis, SEM, Dynamic Molecular simulation, Dynamic-Mechanical analysis and DSC in order to confirm the structure of hydrogels and to predict the best ratio composition with enhanced physical chemical properties. The swelling behavior in water was studied as a function of ratio of monomers and their concentration in medium. An increase in AMPS content led to expansion of network and increase in swelling degree capacity in water. An increase in AMPS content did not significantly influence the glass transition temperature of copolymers, indicated that the physical properties of initial components were preserved. The equal amount of monomers contributed to the highest strength of hydrogels. Meanwhile, the introduction of AMPS to the system was an effective method for improving the performances of the poly(methacrylic acid)- based hydrogels. (C) 2016 Elsevier B.V. All rights reserved.

The aim of this study was the development of novel polysaccharide based films intended to be used as edible food packaging material. The films were prepared by solution casting method using highly methoxylated pectin (PEC) and poly(ethylene glycol) (PEG) of various molecular weights (400, 600 and 1000 gmol(-1)) in different ratios (5:1, 3:1 and 1:1). The film formation was supported by hydrogen bonding between PEC and PEG, which was evidenced by means of ATR-FTIR and NMR analysis. TGA revealed that generally PEG behaves like a pro-degrading agent for pectin, except in the case of PEC/PEG film with a ratio of 1:1. Furthermore, DSC thermograms indicated that PEG1000 exists as a separate phase in the pectin matrix while the formulations with PEG400 and PEG600 showed mainly amorphous morphology. The addition of PEG enhanced the plasticization of PEC films, as evidenced by progressive decreasing of the glass transition temperature values (T-g). The tensile test measurements showed that increasing concentration of PEG produced weaker and more flexibile films. Due to the increased molecular mobility, the pectin phase became more permeable to water vapor as the PEG concentration increased. The obtained results showed that the combination of both polymers resulted in interesting bio -inspired edible films with the potential to compete with commercially used synthetic package materials. This is the peer-reviewed version of the article: Šešlija, S., Nešić, A., Ružić, J., Kalagasidis Krušić, M., Veličković, S. J., Avolio, R., Santagata, G.,& Malinconico, M. (2018). Edible blend films of pectin and poly(ethylene glycol): Preparation and physico-chemical evaluation. Food HydrocolloidsElsevier Sci Ltd, Oxford., 77, 494-501. [https://doi.org/10.1016/j.foodhyd.2017.10.027] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/2473]

The aim of this paper is to present image analysis as a useful technique for fast, reliable and non-destructive detection of dimensional and structural changes in polymers. The possibility of applying image analysis was demonstrated in the case of solvent-induced crystallization of poly(ethylene terephthalate) (PET) containers filled with commonly used organic solvents: chlorobenzene, isophorone, xylene, Espesol, Shellsol A 100, Solvesso 150, propylene glycol, glycerin and water and subjected to the storage stability test at 54 ?C for 14 days (CIPAC 1-MT 46.1.3). In addition, the obtained results were analyzed using one-step analysis of variance (ANOVA) combined with the Duncan?s statistical test (p

Films of chitosan and poly(itaconic acid) in various different ratios have been prepared by membrane casting. The enhancement in the proton conductivity and uptake of water was observed as the content of poly(itaconic acid) in film increased. The proton conductivity of chitosan/poly(itaconic) films was comparative with commercially used synthetic sensor Nafion 117. Films showed thermal stability up to 185 degrees C. The proposed experiment might open up a new possibility for use of chitosan/poly(itaconic acid) films as a biosensors due to their advantages: low cost, simple preparation and good conductive sensitivity. (C) 2015 Elsevier B.V. All rights reserved.

The poor stability and tendency to agglomerate of unfunctionalized nano-SiO2 in the presence of ionic species presents a challenge for preparing poly(methacrylic acid)/nano-SiO2 nanocomposite (NC) hydrogels with desired strength and swelling capability. We proposed a facile and eco-friendly method for the preparation of PMAA/SiO2 NC hydrogels using unfunctionalized silica nanoparticles (NPs) in the form of a suspension. SEM and TEM analyses showed that the NP distribution in the polymer matrix highly depended on the particle concentration. At lower concentrations (up to 13.9 wt %), the NPs were uniformly dispersed as single nanoparticles. With an increase in NP concentration, homogeneously dispersed nanoscale aggregates were formed, while a further increase in the silica concentration led to the formation of homogeneous structures consisting of mutually interacting nanosilica particles coated with PMAA. Swelling experiments confirmed that the silica NPs behaved as adhesive fillers that interacted with PMAA chains, causing the formation of a thin polymer layer strongly adsorbed at the particle interface. The thicknesses of the adsorbed polymer layer, as well as the swelling kinetic parameters, were strongly influenced by nanoparticle size and concentration. Combining nanosilica and PMAA in the form of a soft hydrogel network provided stabilization of the NPs and ensured better mechanical properties of the obtained NC hydrogels compared to pure polymer matrix. The optimal loadings, necessary to ensure the most improved dynamical-mechanical properties, were found in the case of the formation of homogeneously dispersed, nanosized silica aggregates in a PMAA matrix.

Materials based on polystyrene and starch copolymers are used in food packaging, water pollution treatment, and textile industry, and their biodegradability is a desired characteristic. In order to examine the degradation patterns of modified, biodegradable derivates of polystyrene, which may keep its excellent technical features but be more environmentally friendly at the same time, polystyrene-graft-starch biomaterials obtained by emulsion polymerization in the presence of new type of initiator/activator pair (potassium persulfate/different amines) were subjected to 6-month biodegradation by burial method in three different types of commercially available soils: soil rich in humus and soil for cactus and orchid growing. Biodegradation was monitored by mass decrease, and the highest degradation rate was achieved in soil for cactus growing (81.30 %). Statistical analysis proved that microorganisms in different soil samples have different ability of biodegradation, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. Grafting of polystyrene on starch on one hand prevents complete degradation of starch that is present (with maximal percentage of degraded starch ranging from 55 to 93 %), while on the other hand there is an upper limit of share of polystyrene in the copolymer (ranging from 37 to 77 %) that is preventing biodegradation of degradable part of copolymers.

Pectin, with its tendency to gel in the presence of metal ions has become a widely used material for capturing the metal ions from wastewaters. Its dye-capturing properties have been much less investigated, and this paper is the first to show how films based on amidated pectin can be used for cationic dye adsorption. In the present study amidated pectin/montmorillonite composite films were synthesized by membrane casting, and they are stable in aqueous solution both below and above pectin pK(a). FTIR, thermogravimetry and SEM-EDAX have confirmed the presence of montmorillonite in the cast films and the interactions between the two constituents. In order to evaluate the cationic dye adsorption of these films Basic Yellow 28 was used, showing that the films have higher adsorption capacity compared to the others reported in the literature. The results were fitted into Langmuir, Freundlich and Temkin isotherms indicating an exothermic process and setting the optimum amount of montmorillonite in the films to 30% of pectin mass. According to the Langmuir isotherm the maximum adsorption capacity is 571.4 mg/g. (C) 2013 Elsevier B.V. All rights reserved.

Composites based on poly(methacrylic acid) (PMAA) and two types of zeolite, hydrophilic zeolite A and hydrophobic zeolite ZSM-5, were synthesized. The obtained hydrogel composites that combine well the strong interaction between PMAA and cationic species, the accessibility of active sites in the swollen network and fine mechanical stability of zeolites are considered promising candidates for removal of cationic dye, basic yellow 28 (BY28) from aqueous solutions. The adsorption was found to be highly dependent on composition of hydrogel composites, initial dye concentration, solution pH, sorbent mass and temperature, while the effect of zeolite type is less manifested. It was found that the surface adsorption influenced the kinetics of adsorption which was determined by the rate of movement of the boundary layer of BY28 adsorbed on hydrogel surface. Adsorption processes were found to be favorable and preferably physical in nature with maximum adsorption capacity that could reach up to 180 mg/g for PMAA/30A hydrogel composite. Image analysis was applied on differently colored hydrogels and revealed the linear correlation between equilibrium adsorption capacities and the mean values of pixel intensity, as well as the strong effect of initial dye concentration on uniformity of coloration along the hydrogel diameter.

Poly(methacrylic acid) based hydrogels with neutralization degree of monomer of 0% (PMAA/0) and 80% (PMAA/80) were synthesized and their sorption potentials toward model cationic dye, basic yellow 28 (BY28), from aqueous solution, were investigated. FTIR and SEM analysis were conducted to confirm the structure and morphology of the sorbents. Investigation of the effect of the initial dye concentration, the solution pH, the sorbent mass and the temperature on sorption process, as well as the sorption kinetics and equilibrium studies were performed by batch technique. Sorption capacities of both sorbents showed to be highly sensitive to external conditions change, especially those affecting hydrogel swelling degree. Kinetic studies showed that the pseudo-first order kinetic model well fitted the experimental data and that sorption of BY28 onto PMAA hydrogels could be very well described with phase-boundary controlled models. Thermodynamical data revealed spontaneous endothermic processes. In case of PMAA/0 hydrogel physisorption was dominant, while in case of PMAA/80 hydrogel, both, the physisorption and chemisorption were presented. Langmuir, Freundlich and Dubinin–Radushkevich sorption isotherms were applied on equilibrium sorption data. The saturated sorption amount could reach up to 102 mg g −1 and 157 mg g −1 for PMAA/0 and PMAA/80 hydrogel, respectively. Image analysis proved to be useful method for analysis of uniformity of coloration along the hydrogel diameter. Both hydrogels displayed good properties in cationic dye removal, but higher sorption capacities, percentage of removed dye and significant acceleration of sorption of BY28 were accomplished by neutralizing the monomer up to 80%.

Mimicking the extraordinary performances of natural materials presents an attractive, but challenging approach in the synthesis of advanced functional materials. In the field of separation techniques, the design of a low-cost, regenerative, environmentally friendly sorbent and the utilization of most of its active centers to remove the targeted pollutant are everyday challenges. The combination of casein and poly(sodium methacrylate) (PMANa) in the form of a soft polymer network is proposed as a promising sorbent for the removal of Ni2+ from wastewater. Such a combination and an applied synthetic route form hybrid materials with better sorption properties than both their components alone. SEM and TEM show that caseinate micelles are dissociated and the more exposed protein structure is stabilized by the PMANa network and able to form various stable complexes. The achieved sorption capacity (224 mg g(-1)) is among the highest reported in the literature. The very high removal efficiency in the wide range of the initial Ni2+ concentrations (0.05-200 ppm) and easy and complete regeneration without decrease in sorption capacities make these low-cost materials highly sensitive sorbents attractive for use under real conditions where it is necessary to avoid environmental risks and provide the recovery and reuse of the metal.

The effects of heating mode (conventional isothermal heating (CIH) and microwave isothermal heating (MWIH) on the kinetics of polymerization and the properties important for the application (residual monomer, hardness, and water absorption) of three commercial poly(methyl methacrylate) (PMMA) base dental materials were investigated. The degree of monomer conversion was determined by infrared spectrometry. The hardness of the polymerized samples was measured by shore D method, whereas the water absorption was measured gravimetrically. Kinetics models for polymerizations using different heating modes were determined by model fitting method. The rate of the MWIH polymerization was eight times higher compared with the CIH polymerization. The CIH polymerization is found to be the phase–boundary controlled reaction for which the rate of contracting volume is the rate limiting step, whereas MWIH polymerization is found to be the first-order reaction and the monomer concentration in the polymerization mixture is the rate limiting step. The samples of PMMA base dental materials synthesized by MWIH polymerization exhibit better application properties (hardness and water absorption). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Poly(methacrylic acid) hydrogels were synthesized. The effects of the synthesis parameters: the neutralization degree of methacrylic acid and the concentrations of monomer, crosslinker and initiator on the xerogels structural properties: the xerogel density ( ρ xg ), the number average molar mass between the network crosslinks ( M c ), the crosslink degree ( ρ c ), the number of elastically effective chains totally induced in a perfect network per unit volume ( V e ), the distance between the macromolecular chains ( ξ ) and the equilibrium swelling degree ( SD eq ) and the swelling kinetics was investigated. As the concentrations of crosslinker, monomer and initiator increase, the value of ρ xg , ρ c and V e increases and decreases the value of M c , ξ and SD eq . With the increase in the neutralization degree of methacrylic acid, the values of ρ xg , M c , ξ , SD eq increase, while the ρ c and V e decrease. The xerogels structural properties, SD eq and swelling kinetic parameters are mainly in power law form functional relationships with the synthesis parameters as well as with the xerogels crosslinking degree.

The aim of the work reported here was to investigate temperature- and pH-sensitive hydrogels of N-isopropylacrylamide (NIPAM) and itaconic acid (IA) and their semi-interpenetrating polymer networks (semi-IPNs) with varying contents of poly(ethylene glycol) (PEG). The stimuli responsiveness, swelling behaviour and mechanical properties of the hydrogels and semi-IPNs were studied in order to investigate the effect of various amounts of PEG. Pulsed-gradient spin-echo NMR experiments were carried out to investigate the diffusion process. The pH sensitivity increased with an increasing amount of PEG in the semi-IPNs, while the overall rate of water uptake was diffusion-controlled (n < 0.5). For certain PEG contents (5 and 10 wt%), the semi-IPNs exhibited better mechanical properties than the poly(NIPAM-co-IA) copolymer. The calculated values of the self-diffusion coefficients of water indicated facilitated diffusion of water through the system with increased amounts of PEG, while the self-diffusion coefficients of a model compound, metoprolol tartrate, showed no significant dependence on the amount of PEG. According to the results obtained and compared to results reported in the literature, the investigated semi-IPNs may have potential applications in the controlled release of macromolecular active agents such as proteins and peptides.

Environmental protection has been a topic of great interest in recent years. Discharging azo dyes in aquatic systems contaminates water and causes serious ecological problems. Azo dyes are bio-accumulative, and, due to allergenic, carcinogenic and mutagenic properties, are a grave threat to people and the environment. Because of economic feasibility, simplicity and a high efficiency, adsorption is the most suitable process for treatment of wastewater. The increasingly interesting bio-degradable adsorbents are those that stem from ecologically and economically sustainable sources. The aim of the study is preparation and characterisation of polymer complexes based on naturally occurring polysaccharide-chitosan and poly( itaconic acid), as an adsorbent for removal of Reactive Orange 16 dye from wastewater. The complexes are characterised by Fourier-Transform Infrared Spectroscopy and Scanning electron microscopy. The effect of initial dye concentration, temperature and pH value of the solution on the adsorption capacities is investigated. Comparison of the obtained results with reported data shows the studied complex being an efficiently replacement for conventional adsorbents removing Reactive Orange 16 from wastewater. Sustainable Development, Knowledge Society and Smart Future Manufacturing Technologies, Proceedings, Jun 27-30, 2012, Jurmala, Latvia

This study investigates a wide range of clinically relevant mechanical properties of poly(methyl methacrylate) (PMMA) denture base materials modified with di-methyl itaconate (DMI) and di-n-butyl itaconate (DBI) in order to compare them to a commercial PMMA denture base material. The commercial denture base formulation was modified with DMI and DBI by replacing up to 10 wt% of methyl methacrylate (MMA) monomer. The specimens were prepared by standard bath curing process. The influence of the itaconate content on hardness, impact strength, tensile, and thermal and dynamic mechanical properties was investigated. It is found that the addition of di-n-alkyl itaconates gives homogenous blends that show decreased glass transition temperature, as well as decrease in storage modulus, ultimate tensile strength, and impact fracture resistance with increase in the itaconate content. The mean values of surface hardness show no significant change with the addition of itaconates. The magnitude of the measured values indicates that the poly(methyl methacrylate) (PMMA) denture base material modified with itaconates could be developed into a less toxic, more environmentally and patient friendly product than commercial pure PMMA denture base material.

The aim of this work was to examine the possibility of modification of commercial denture base materials with itaconic acid esters, in order to obtain material with less toxicity and higher biocompatibility. Despite their relatively higher price compared to methacrylates, itaconic acid and itaconates are materials of choice for environmentally friendly applications, because they are not produced from petrochemical sources, but from plants. Commercial system based on poly(methyl methacrylate) was modified using ditetrahydrofurfuryl itaconate (DTHFI), wherein the ratio of DTHFI was varied from 2.5 to 10% by weight. Copolymerization was confirmed using FTIR spectroscopy, while SEM analysis showed the absence of micro defects and pores in the structure. The effect of the itaconate content on the absorption of fluids, the residual monomer content, thermal, dynamic-mechanical and mechanical properties (hardness, toughness, stress and elongation at break) was investigated. It was found that the addition of DTHFI significantly reduced the amount of residual methyl methacrylate, what made these materials less toxic. It was shown that the increase in DTHFI content gave materials with decreased glass transition temperature, as well as with decreased storage modulus, ultimate tensile strength and impact fracture resistance, however mechanical properties were in the rang prescribed by ADA standards, and can be used in practice. The deterioration of mechanical properties was therefore worth losing in order to gain lesser toxicity of the leached monomer. [Projekat Ministarstva nauke Republike Srbije, br. 172062: Synthesis and characterization of novel functional polymers and polymeric nanomaterials]

In this study novel copolymer hydrogels based on methacrylic acid (MAA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were synthesized by free-radical aqueous copolymerization and characterized. Derived P(MAA-co-AMPS) hydrogels, joining well the affection of numerous anionic groups toward cations and the accessibility of active sites in the swollen network were recognized as potential sorbents for removal of cationic species. The effect of various initial parameters on sorption of two cationic dyes onto P(MAA-co-AMPS) hydrogels was investigated in both, single and binary, systems. Results showed that the copolymerization of MAA and AMPS significantly increased sorption capability of copolymers compared to both pure-component hydrogels-PMAA and PAMPS hydrogels. The main advantage of novel copolymer hydrogels is enhanced sorption of dyes in binary systems, reaching maximal values of 98.8% (Basic Yellow 28) and 96.4 (Basic Red 46), onto hydrogel P (MAA-co-AMPS) 50/50. The desorption rate of BY28 and BR46 in both, single and in binary, systems increased with the increase in AMPS content in hydrogels. This investigation showed that copolymerization of two acidic monomers, bearing different types of acid groups, could significantly improve the sorption thus decreasing the price and the amount of material needed for successful removal of pollutants. (C) 2015 Elsevier B.V. All rights reserved.

The diffusion of water into solid poly(ditetrahydrofurfuryl itaconate) (PDTFI) films and in analogous polymer solutions was measured. Diffusion into solid PDTFI films on a glass support was measured in three solutions of different pH (4, 7 and 10) at 37 and 60 degrees C during a 90 day period. The uptake was high and was both pH and. temperature dependent, ranging from 120 to 2000%. A Fickian mechanism is observed for the initial stages of uptake, whilst a non-Fickian mechanism is present when the equilibrium is approached. The pH 7 samples did not equilibrate at any temperature during the experiment. The FTIR investigations of the films indicated some deesterification took place during the uptake. The diffusion coefficients and diffusion exponents are calculated for the samples. The diffusion of water into PDTFI solution in acetone was measured by PGSE-NMR, showing the expected linear attenuation functions. The diffusion coefficient of water was calculated for polymer concentrations up to 10%.

Polystyrene graft corn starch copolymers (PS-g-starch) were synthesized by emulsion polymerization using sodium dodecylsulfate (SDS) as the emulsifier and potassium persulfate (PPS) as the initiator. Influences of temperature (25-75 A degrees C), monomer (0.56-0.96 mol/dm(3)) and initiator (0.007-0.020 mol/dm(3)) concentration, reaction time (15-300 min), and type of amine activator and its concentration (0.005-0.08 mol/dm(3)) on the percentage of grafting (G, %) and yield (Y, %) were investigated. Amines showed dual impact on grafting reaction, some of them were activators and other were inhibitors, where N,N-dimethylethanolamine gave the maximal and 1-(2-hydroxyethyl) piperazine gave the minimal value of percentage of grafting. The maximum percentage of grafting was 32.55 %, while in case of piperazine derivate percentage of grafting was zero. Successful grafting was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The maximum percentage of grafting was obtained under the following reaction conditions: 10.00 g of starch, monomer concentration was 0.96 mol/dm(3), initiator concentration was 0.015 mol/dm(3), reaction time was 15 min, temperature of 75 A degrees C, and N,N-dimethylethanolamine was used as activator in concentration of 0.01 mol/dm(3).

Asymmetric polyethersulfone membranes with submicron particles comprising crosslinked glycidyl methacrylate copolymer were prepared by a combination of a traditional immersion precipitation process for making membranes with photopolymerization and crosslinking of functional monomers included in the casting solution. As the concentration of polymerizable monomers increased the original macrovoid structure was replaced by a hybrid morphology with microglobules typical of macroporous methacrylate adsorbers embedded within microporous structure with no significant effects on water permeability. The epoxide groups present in glycidyl methacrylate copolymer were transformed into amine functionalities by ring opening under alkaline conditions. Permeation of Orange G solution at low transmembrane pressures was used to demonstrate suitability of these novel membranes for membrane adsorption. Supplementary information: [https://technorep.tmf.bg.ac.rs/handle/123456789/2577]

In this paper, a biodegradation study of grafted copolymers of cornstarch and polystyrene (PS) and cornstarch and poly(methacrylic acid) in model river water is described. These copolymers were obtained in the presence of different amine activators. The synthesized copolymers and products of degradation were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Biodegradation was monitored by mass decrease and the number of microorganisms by the Koch method. Biodegradation of both copolymers advanced with time, the starch-graft-poly(methacrylic acid) copolymers had completely degraded after 21 day, and the starch graft polystyrene had partially degraded (45.8-93.1 % mass loss) after 27 days. The differences in the degree of biodegradation are the consequences of the different structures of the samples, and there was a significant negative correlation between the share of polystyrene in the copolymer and the degree of biodegradation. The grafting degree of PS necessary to prevent biodegradation was 54 %. Based on experimental evidence, the mechanisms of both biodegradation processes are proposed, and influence of degree of starch and synthetic component of copolymers on the degradation of the samples were established. U ovom radu proučavana je biodegradacija kalemljenih kopolimera kukuruznog skroba i polistirena i kukuruznog skroba i poli(metakrilne kiseline) u rečnoj vodi. Ovi kopolimeri su sintetisani u prisustvu različitih aminoaktivatora. Sintetisani kopolimeri i produkta biodegradacije su karakterisani FTIR spektroskopijom i SEM mikroskopijom. Biodegradacija je praćena gubitkom mase uzoraka, a broj mikroorganizama Kohovom metodom. Stepen biodegradacije obe vrste kopolimera raste sa vremenom. Kalemljeni polimeri skroba i poli(metakrilne kiseline) potpuno se razgrađuju za 21 dan, dok se polimeri na bazi skroba i polistirena delimično razgrađuju nakon 27 dana (45,8-93,1 % od ukupne mase). Razlike u stepenu biodegradacije su posledica različite strukture uzoraka, a postoji i značajna negativna korelacija između udela polistirena u kopolimeru i stepena biodegradacije. Stepen kalemljenja polistirena (udeo polistirena u kopolimeru) koji sprečava biodegradaciju iznosio je 54 %. Na osnovu eksperimentalnih dokaza, predloženi su mehanizmi oba biodegradaciona procesa i ustanovljeni su uticaji količine skroba i sintetske komponente kopolimera na biodegradaciju.

This study represents new material based on chitosan modified by zeolite A as adsorbent for anionic dye, using Bezactive Orange 16 as a model compound. Interactions between dye and chitosan/zeolite A film at initial concentrations and pH dye solution was investigated. In order to determine kinetics and the mechanism of adsorption four kinetic models were used. The results showed that the adsorption of Bezactive Orange 16 dye onto chitosan/zeolite A can be best described by pseudo-second order model. According to the Langmuir model, the maximum adsorption capacity reached 305.8 mg/g. The films could be potentially used as absorbents for anionic dye removal in wastewater treatment process. (C) 2013 Elsevier Ltd. All rights reserved.

The synthesis, characterization and environmental application of chitosan/montmorillonite membrane for adsorption Bezactiv Orange V-3R were investigated. Chitosan/montmorillonite membranes were synthesized in different ratios, containing 10-50% of montmorillonite (MMT) in membrane. These membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy (SEM). The adsorption kinetics were investigated using three different concentrations of Bezactiv Orange dye (30, 50 and 80 mg/L). The adsorption capacity increases with increasing amount of MMT in membranes. These membranes show the highest adsorption capacity when the initial dye concentration was 80 mg/L The results show that the optimum condition for adsorption of Bezactiv Orange is pH 6. A comparison of kinetic models was evaluated for the pseudo-first and pseudo-second order and intra-particle diffusion. The experimental data were fitted to the pseudo-second order kinetic model, and also followed by intra-particle diffusion. Intra-particle diffusion is not the only rate-controlling step. The Langmuir and Freundlich adsorption isotherms were applied to experimental equilibrium data at different concentration of dye solution. The results indicated the competency of chitosan/MMT membranes adsorbent for Bezactiv Orange adsorption. (C) 2012 Elsevier B.V. All rights reserved.

The aim of this work was synthesis of grafted copolymers of poly(methacrylic acid) and starch (PMAA-graft-starch) with high percentage of grafting, G (%). The effect of temperature (55-75 degrees C), concentration of methacrylic acid monomer (0.775-1.452 mol/dm(3)), amount of initiator potassium persulfate (PPS) (0.00075-0.0025 mol), reaction time (30-270 min) and nature and amount (0.001-0.005 mol) of amine activator on percentage of grafting were investigated. The following amine activators were used: N,N-dimethylaminoethanol. N,N-diethylaminoethanol, triethylamine, propylamine, iso-butylamine, pentylamine, hexylamine, 4-(2-hidroxyethyl) morpholine and 1-(2-hidroxyethyl) piperazine. The graft copolymer was characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. The highest G was 40.92%. Reaction conditions were as follows: 10.00 g of starch, monomer concentration was 0.775 mol/dm(3), temperature of 70 degrees C, the amount of PPS was 0.001 mol. The 4-(2-hidroxyethyl) morpholine was used as amine activator in amount of 0.001 mol. (C) 2012 Elsevier Ltd. All rights reserved.

This study evaluated the water absorption, solubility, kinetics of water diffusion and residual monomer content of commercial poly(methyl methacrylate) (PMMA) denture base material modified with dimethyl itaconate (DMI) and di-n-butyl itaconate (DBI). Water absorption and solubility were measured gravimetrically while the residual monomer content was analysed using high-performance liquid chromatography with ultraviolet detection. It was found that the addition of di-n-alkyl itaconates significantly decreases the residual methyl methacrylate (MMA) content in the polymerized material. Maximum uptake (M∞) and loss (M′∞), and diffusion coefficients for absorption (Da) and desorption (Dd) of water through all materials were established. M∞ shows a linear decrease with increasing amount of itaconate in the system while Da shows a linear increase with increasing amount of itaconate, both of these effects being more pronounced when DBI is present compared to DMI. M∞ is a linear function of the value of Hoy's solubility parameter. The reduction in residual MMA promoted by addition of a small amount of di-n-alkyl itaconates can improve the applicative properties and biocompatibility of the PMMA denture base material. Also, it is shown that modification of the denture base material with di-n-alkyl itaconates can enable precise control of water absorption in the system. Copyright © 2012 Society of Chemical Industry

Complexes based on amidated pectin (AP) and poly(itaconic acid) (PIA) were prepared by casting films from solutions of AP and PIA in different ratios with the pectin amount ranging from 10% to 90% by mass. The complexes were investigated by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG). In all investigated ratios of AP/PIA glassy transparent films with a uniform structure were obtained. The results of elemental analysis confirmed the composition of the complexes, and FTIR spectroscopy has shown carboxylic and amide peak shifting, indicating complex formation between AP and PIA. Comparison of thermograms of AP/PIA films with different ratios of AP indicated that the increase of the amount of AP increases the thermal stability of the films by retarding the onset of the main degradation processes. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/2903]

The goal of this investigation was to study the thermal degradation of poly(ditetrahydro-furfuryl itaconate) (PDTHFI) by thermogravimetry (TG). The monomer was polymerized in bulk at 40 degreesC using AIBN as initiator. Non-oxidative degradation was studied under nitrogen, while oxidative degradation was studied under air, applying four heating rates (2.5, 10, 20 and 40 K/min), up to 600 degreesC. The apparent activation energy of thermal degradation, E-a, was calculated using the Flynn-Wall method. The obtained non-oxidative TG curves of PDTHFI are parallel and no heating rate effect was observed. A carbonaceous residue remained at 600 degreesC, regardless of the heating rate applied. The E-a of PDTHFI is constant in the whole mass loss range and its mean value is 124 kJ/mol. The non-oxidative differential TG (DTG) curves of PDTHFI consist of two peaks, the second being dominant. If it is assumed that depolymerization is the main degradation mechanism, analogous to other polyitaconates, these two peaks could be ascribed to two depolymerization initiation modes: end-chain beta -scission and random main chain scission. The oxidative TG curves are more complex than the non-oxidative ones and show a heating rate effect. The E-a steadily increases in the mass loss range of 5-50% from 120 to 200 kJ/mol. The oxidative DTG curves consist of a major peak with two shoulders and a second minor peak.

Non-oxidative and oxidative thermogravimetry was performed on poly(di- n -propyl-) (PDnPI), poly(di-iso-propyl-) (PDiPI), poly(di- n -butyl-) (PDnBI), poly(di-iso-butyl-) (PDiBI) and poly(di-sec-butyl itaconate) (PDsBI). The results show that PDiPI and PDsBI thermally degrade in a similar manner with deesterification being, together with depolymerisation, a significant mechanism. PDnPI and PDnBI also degrade in a similar manner by depolymerisation, with chain end initiation being more important than random main chain scission initiation. The results for PDiBI indicate more similarity to the n -alkyl esters than to the other branched chain esters although, there are indications that also with this polymer ester decomposition is not an insignificant thermal degradation mechanism. Although little can be said about the mechanism of oxidative thermal degradation of these polymers, the kinetic data again show the similarity between PDnPI and PDnBI on the one hand, and PDiPI and PDsBI on the other. Also, in an oxidative atmosphere, PDiBI shows more similarity to the n -alkyl esters than to PDiPI and PDsBI. It would appear that, as with the polymethacrylates, the number of β-hydrogen atoms in the ester substituents plays a dominant role in determining the mechanism of both the thermal and thermo-oxidative degradation of these polymers.

The Li-, Na- and K salts of poly(itaconic acid) (PIA) were prepared by treating the polyacid with the corresponding aqueous hydroxide. The resulting polysalts were analysed by elemental analysis, FTIR spectroscopy and thermogravimetry. The results indicate that the polysalts are thermally more stable than the parent PIA, they all degrade in a similar manner and somewhat more complexly than the poly(methacrylic acid) salts.

The effects of plasticizers on poly(vinyl chloride) (PVC) plastisol mixtures were investigated. The investigations were carried out by determining the density of the PVC foam obtained by gelling the plastisol, as well as its elasticity and degree of expansion. Two series of experiments using different types of PVC were performed, using eight plasticizers, individually or as mixtures. Two-component plasticizer mixtures showed better properties than single-component plasticizers, and mixtures of di-iso-heptyl phthalate (DiHP) and butyl benzyl phthalate (BBP) proved to be the most appropriate. The effect of plasticizer amount also was investigated, and of the three parameters studied, the foam density, which steadily increased with plasticizer amount, was the critical one. It was also shown that in order to obtain consistent results, the foam expansion had to be precisely timed and the temperature carefully chosen.