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Some vinyl polymers/montmorillonite nanocomposites were prepared via in-situ-atom transfer radical polymerization (ATRP) in presence of clay. Methyl methacrylate, styrene and n-butyl methacrylate were involved in the formation of such polymeric nanocomposites. Their dielectric properties were extensively studied to invest them in the a.c. power applications. Several dielectric parameters such as dielectric constant loss (e") and a.c. conductivity (σ) were measured at both different frequencies (0.1 Hz to 100 KHz) and temperature ranged from (20℃ to 90℃). From the dielectric results, it was realized that the dielectric a.c. conductivity was enhanced by increasing the temperature for the four prepared polymer nanocomposites.

Chitosan biguanidine hydrochloride (ChG) and low molecular weight poly[( R )-3-hydroxybutyrate] (PHB) were successfully prepared to overcome the solubility problem of chitosan and PHB and also to enhance antimicrobial activity of chitosan. The graft copolymers based on ChG and PHB (ChG-grafted PHB) were then prepared via condensation reaction of the carboxylic groups of PHB with the amino groups of ChG. These graft copolymers swell in water. The prepared graft copolymers were characterized by FTIR, 1 H NMR, X-ray diffraction (XRD) and thermal analyses (TGA and DSC). TGA and DSC results revealed that the thermal stability and crystallinity of the graft copolymers were found to increase as the content of PHB increased. The antimicrobial activity of both ChG and ChG-grafted PHB, against Streptococcus pneumoniae , Bacillus subtilis , Escherichia coli (as examples of bacteria) and Aspergillus fumigatus , Geotricum candidum and Syncephalastrum recemosum (as examples of fungi), were tested. Among them, ChG and ChG-grafted PHB with the highest grafting percent investigated showed to possess relatively higher antimicrobial activity with low MIC values in the range of 0.49–3.90 μg mL −1 .

In the present work, poly(n-alkyl itaconate-co-vinyl acetate) comb-like polymers were synthesized by radical copolymerization of n-alkyl itaconates of various alkyl chain length and vinyl acetate monomers for use as pour point depressants in lubricant oil. Initially four n-alkyl itaconate monomers were synthesized by esterification of itaconic acid with a series of n-alkyl alcohol, having different alkyl chain length C16/C18/NAFOL 20 + A (Cav = 20)/NAFOL 1822 B (Cav = 22). The copolymerization of these monomers with vinyl acetate was then performed using dibenzoyl peroxide in toluene at 120°C up to high conversion, with molar ratios of 0.25:0.75, 0.50:0.50, and 0.75:0.25 for alkyl itaconate: vinyl acetate. All products were characterized by FTIR, 1H NMR and gel permeation chromatography (GPC). These copolymers were tested in terms of their suitability as pour point depressants and flow improvers for lube oil. The obtained data revealed that the prepared compounds depress the pour point of the lube oil suc...

Blend hydrogels composed of carboxymethyl chitosan (CMCh) and poly (acrylonitrile) (PAN) were synthesized via crosslinking method. Several analyses were made to investigate both physical and thermal properties of CMCh/PAN hydrogels like; FTIR, scanning electron microscope, XRD and thermogravimetric analysis (TGA). TGA results showed that CMCh/PAN hydrogels are thermally more stable than CMCh and their thermal stability increases as PAN content increases in the hydrogel. Moreover, the swelling behavior of CMCh/PAN hydrogels was studied in different buffer solutions. It was found that CMCh/PAN hydrogels swell much more than PAN especially at pH 9. The hydrogels sorption for different dyestuff and various metal ions like; Cu2+, Cd2+ and Co2+ were also studied. In this work, antibacterial characteristic of hydrogels was mainly investigated towards Escherichia coli (E. coli) as a serious disease-leading bacterium. All tested hydrogels have clearly presented good antibacterial activity as CMCh content increases in the hydrogels.

Hydrogels composed of poly(vinyl alcohol) (PVA) and carboxymethyl chitosan (CMCh) were synthesized via ultraviolet (UV) irradiation that can be used in several industrial fields. Several analysis tools were used to characterize the physical and thermal properties of CMCh/PVA hydrogels namely FT-IR, scanning electron microscope (SEM), XRD, thermogravimetric analysis (TGA), and differential scanning calorimetery (DSC). TGA results showed that CMCh/PVA hydrogels are thermally more stable than CMCh and their thermal stability increases as PVA content increases in the hydrogel. Also, DSC results showed that CMCh/PVA hydrogels are at least partial miscible blends. Moreover, the swelling behavior of the CMCh/PVA hydrogels was studied in different buffered solutions and in different salt solutions at various concentrations. CMCh/PVA hydrogels swell much more than CMCh especially at alkaline pH. Both metal and dye uptake were studied for CMCh/PVA hydrogels. The hydrogels adsorb much more dyestuff and metal ions like Cu2+, Cd2+, and Co2+ than CMCh itself. Much dyestuff and metal ions are adsorbed by the hydrogels as PVA content increases in the hydrogel. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Pyrazolodithiones of expected biological activity were examined as thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride) (PVC) in air at 180 °C. Their high stabilizing efficiency were shown by their high thermal stability values (T s), which is the time needed for the liberation of HCl gas, if compared with dibasic lead carbonate (DBLC) and calcium–zinc soap (Ca–Zn soap) reference stabilizers used industrially, with better extent of discoloration. Blending these derivatives with reference stabilizers in different ratios greatly lengthens the thermal stability value and improves the extent of discoloration of the PVC. The structure of the novel organic stabilizers was confirmed by elemental analysis, FTIR, Mass spectra, and 1H-NMR. Thermogravimetric analyses confirmed the improved stability of PVC in the presence of the investigated organic stabilizers, compared to blank PVC and PVC stabilized with the reference stabilizers. Also, GPC measurements were done to investigate the changes occurred in the molecular masses of the degraded samples of PVC in presence of the newly synthesized stabilizers. The stabilizing efficiency of pyrazolodithiones is attributed to the replacement of the labile chlorine atoms on the PVC chains by a relatively more stable moiety of the organic stabilizer. The investigated stabilizers showed a good antimicrobial activity toward two kinds of bacteria, Escherichia coli and Staphylococcus aureus; and also toward two kinds of fungi, Aspergillus flavus and Candida albicans. They also exhibited antitumor activity against both liver and colon human cell lines.

A novel super absorbent polymer was prepared by graft copolymerization of 4-vinyl pyridine (4VP) onto the chains of carboxymethyl chitosan in aqueous solution using potassium persulphate (KPS) as initiator. The effect of monomer and initiator concentration, reaction temperature, and time on the grafting yield has been investigated. The maximum grafting yield was achieved at [KPS] = 4 × 10−2 mol/L, [M] = 2.5 mol/L at reaction temperature = 60 °C within reaction time = 3 h. The molecular structure of the graft copolymer was confirmed by FTIR, surface morphology before and after the polymerization was examined by SEM. Different analyses were done for the graft copolymer such as X-ray diffraction, solubility tests, and thermal analysis. Different applications were done on the graft copolymer such as swell ability in different pH solutions, dye, and metal uptake.

Carboxymethyl chitosan (CMCh) was prepared and characterized by determinating its degree of substitution and elucidating its structure by elemental analyses and FTIR. Graft copolymerization of acrylonitrile (AN) onto CMCh was carried out in aqueous solution using potassium persulfate (KPS) initiator. Evidences of grafting were obtained via FTIR spectroscopy, elemental analyses, scanning electron microscopy, X-ray diffraction and the differences in swellability profiles before and after grafting. The effects of initiator concentration, monomer concentration, reaction time and temperature on the graft copolymerization were studied by determining the grafting percentage (%G), grafting efficiency (%GE) and the amount of homopolymer formed (%H). The optimum grafting conditions were determined as follows: [KPS] = 5 × 10−2 mol/L, [M] = 3 mol/L, reaction temperature = 65°C and reaction time = 3 h. The capacity of the graft copolymers to uptake metal ions from their aqueous solutions and to capture different types...

Acrylonitrile (AN) was investigated as an important monomer for the graft copolymerization onto chitosan. A number of variables in the grafting reaction were investigated, including initiator and monomer concentration, duration, and temperature of the polymerization reaction. The graft copolymers were evaluated in terms of graft yield, grafting efficiency and % homopolymer. Moreover, modification of grafted chitosan was done by changing the nitrile group (CN) to the amidoxime group (CNOH). Certain characterization for both the grafted Chitosan (Ch-g-PAN) and its amidoxime derivative -as compared to the parent polymer- are measured including the swell ability property, dye uptake, surface morphology, and metal uptake property. The results obtained reflect the feasibility for using Ch-g-PAN as absorbent for both Ni2+ and Co2+ ions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Poly ( N -vinyl imidazole) (PNVI) has been grafted onto carboxymethyl chitosan in aqueous solution using potassium persulphate (KPS) as initiator. The effect of the monomer and initiator concentration, the reaction temperature and time on the grafting yield have been investigated. The maximum grafting yield was achieved at [KPS] = 8 × 10 −2 mol/L, [M] = 1 mol/L at reaction temperature = 60 °C within reaction time = 2.5 h. The grafted products were characterized by FTIR, elemental analysis, SEM photographs, solubility tests, thermal analysis and antibacterial activity. Grafted products have improved the antimicrobial activity of carboxymethyl chitosan.

Vanillin–Schiff’s bases (VSB) were examined as thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride) (PVC) in air at 180 °C. Their high stabilizing efficiency were shown by their high thermal stability value (Ts), which is the time elapsed for the detection of HCl gas, if compared with dibasic lead carbonate and cadmium–zinc soap reference stabilizers used industrially, with better extent of discoloration. Blending these derivatives with reference stabilizers in different ratios greatly lengthens the thermal stability and the extent of discoloration of the PVC. Condensation products of Vanillin with amines are very active biologically, besides having good complexation ability with metal ions. The Ni2+ and Co2+ complexes of VSB derivatives gave better thermal stability and less discoloration than the parent organic stabilizer. Also, blending these complexes with either of the used reference stabilizers in different ratios gave better thermal stability and lower extent of discoloration. Thermogravimetric analysis confirmed the improved stability of PVC in the presence of the VSB derivatives, compared to blank PVC, PVC stabilized with reference stabilizers and PVC stabilized with binary mixture of VSB derivatives with reference stabilizer. The stabilizing efficiency of Vanillin–Schiff’s base (VSB) derivatives is attributed to the replacement of the labile chlorine atoms on the PVC chains by a relatively more stable moiety of the organic stabilizer.

Biodegradable segmented poly(ester-urethane)s derived from telechelic dihydroxy-poly[(R)-3-hydroxybutyrate], acting as hard segments, and poly(e-caprolactone)-diols, acting as soft segments, using 1,6-hexamethylene diisocyanate, as non toxic connecting agent, were synthesized. The copolymers were characterized with regard to their molecular weight by GPC and their main thermal transitions by DSC. These copolymers as well as PHB were exposed to UV-irradiation for different time intervals and the changes in the chemical structure were analyzed by FTIR spectroscopy. Under our experimental conditions, it was found that the increase of irradiation time was accompanied by increase of the proportion of the gel fraction and the decrease of the intrinsic viscosity of the soluble fraction of the investigated copolymers. The biodegradability of PHB and poly(ester-urethane) sample containing ~40 wt% PHB before and after UV-irradiation was investigated under soil burial. The results showed that the photolysis in air prior to biodegradation increased the rate of degradation.

The thermal degradation behavior of poly(vinyl chloride) (PVC) in presence of poly(glycidyl methacrylate) (PGMA) has been studied using continuous potentiometric determination of the evolved HCl gas from the degradation process from one hand and by evaluating the extent of discoloration of the degraded samples from the other. The efficiency of blending PGMA with dibasic lead carbonate (DBLC) conventional thermal stabilizer has also been investigated. A probable radical mechanism for the effect of PGMA on the thermal stabilization of PVC has been suggested based on data reported by FTIR and elemental analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The thermal degradation behavior of poly (vinyl chloride), PVC, in presence of poly(N-acryloyl-N′-cyanoacetohydrazide), PACAH, has been studied using continuous potentiometric determination of the evolved HCl gas from the degradation process from one hand and by measuring the extent of discoloration of the degraded samples from the other. The efficiency of blending PACAH with dibasic lead carbonate, DBLC, conventional thermal stabilizer has also been investigated. A probable radical mechanism for the effect of PACAH on the thermal stabilization of PVC has been proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Modification of two synthetic rubbers, namely polybutadiene (BR) and bromobutyl (BIIR), were carried out to enhance their adhesion performance and their lining to steel to protect it against corrosion. Two different feasible and industrially applicable techniques were used for grafting the two rubbers under investigation individually with maleic anhydride (MAH), namely the reactive extrusion and the mechanochemical techniques. The modified rubbers were characterized by FTIR-spectroscopy, chemical analysis, elemental analysis, and by measuring the surface wetting tension. These applied techniques improved the adhesion performance of the rubber towards steel surface markedly. Grafting of BR with MAH via mechanochemical technique increased the adhesion strength of BR by four to five times, whereas grafting of BIIR with MAH via reactive extrusion techniques increased the adhesion strength of the parent BIIR up to more than five times. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Graft copolymerization is an attractive method for surface functionalization of natural polymers and can be initiated by chemical methods, radiation technique, and other systems. Polymer grafting onto polysaccharides is an effective method for the synthesis of superabsorbents. Depending upon the type of monomers and the conditions employed the properties of graft copolymers vary to a large extent. Chitosan is a nontoxic, biocompatible polysaccharide, and starch is a natural hydrophilic biopolymer. Both these are most abundant natural organic materials which are extensively investigated in the development of biodegradable and environment-friendly materials. Their hydrogels are of utmost importance for wide use in many fields including structural transplants, target drug delivery, tissue engineering, biosensors, adsorbents, etc. In this chapter, the various techniques used for the synthesis of chitosan/starch graft copolymers, their properties and possible applications are discussed in detail.

Eugenol (4-allyl-2-methoxy-phenol) has been examined as a thermal stabilizer and co-stabilizer for rigid PVC in air, at 180 °C. Its high stabilizing efficiency is detected by its high thermal stability value (Ts) when compared with some of the common reference stabilizers used industrially such as dibasic lead carbonate, calcium–zinc soap and octyl tin mercaptide. Blending this organic stabilizer with some of the reference stabilizers in different ratios had synergistic effect on both the induction period and the dehydrochlorination rate together with the longer extent of discolouration of PVC stabilized by eugenol as compared with the blank and the samples stabilized with reference commercial stabilizers. A probable mechanism for the stabilizing action of eugenol has been proposed. The stabilizing efficiency is attributed partially to the stabilizer's ability to intervene in the radical chain degradation process of PVC and to the replacement of the labile chlorine atoms on PVC chains by a relatively more stable moiety of the organic stabilizer.

The Schiff bases of chitosan were synthesized by the reaction of chitosan with 3-(4-substituted-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde. The structure of the prepared chitosan derivatives was characterized by FT-IR spectroscopy, elemental analysis, and X-ray diffraction studies and thermogravimetric analysis (TG). The results show that the specific properties of Schiff bases of chitosan can be altered by modifying the molecular structures with proper substituent groups.TG results reveal that the thermal stability of the prepared chitosan Schiff bases was lower than chitosan. The activation energy of decomposition was calculated using Coats-Redfern model. The antimicrobial activity of chitosan and Schiff bases of chitosan were investigated against Streptococcus pneumonia, Bacillis subtilis, Escherichia coli (as examples of bacteria) and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum (as examples of fungi). The results indicated that the antimicrobial activity of the Schiff bases was stronger than that of chitosan and was dependent on the substituent group. The activity of un-substituted arylpyrazole chitosan derivative toward the investigated bacteria and fungi species was better than the other derivatives.

N-phenyl-3-substituted-5-pyrazolone derivatives have been examined as thermal stabilizers or co-stabilizers for rigid PVC in air, at 180 °C. Their high stabilizing efficiency is detected by their high induction period values (Ts) when compared with some of the common reference stabilizers used industrially, such as dibasic lead carbonate, calcium–zinc soap and n-octyl tin mercaptide. Blending these derivatives with some of the reference stabilizers in different ratios had a synergistic effect on both the induction period and the dehydrochlorination rate. A probable mechanism for the stabilizing mode of N-phenyl-3-substituted-5-pyrazolone derivatives has been proposed. The stabilizing efficiency is attributed at least partially to the ability of the organic stabilizer to be incorporated in the polymeric chains, thus disrupting the chain degradation.

Anthraquinone and 1-aminoanthraquinone derivatives have been examined as thermal stabilizers or co-stabilizers for rigid PVC in air, at 180 °C. Their high stabilizing efficiency is detected by their high induction period values (Ts) when compared with some of the common reference stabilizers used industrially such as dibasic lead carbonate, calcium–zinc soap and octyl tin mercaptide. Blending these organic stabilizers with some of the reference stabilizers in different ratios had synergistic effect on both the induction period and the dehydrochlorination rate. A probable mechanism for the stabilizing mode of these derivatives has been proposed. The stabilizing efficiency is attributed partially to the stabilizers' ability to intervene in the radical chain degradation process of PVC and to the replacement of the labile chlorine atoms on PVC chains by a relatively more stable moiety of the organic stabilizer.

Four saturated polyesters poly(hexamethylene adipate), poly(ethylene adipate), poly(hexamethylene terephthalate) and poly(ethylene terephthalate) were prepared. The resulting materials were characterized by IR and 1H NMR, end group analysis and gel permeation chromatography. The effect of blending these polyesters (5 and 10%) with poly(vinyl chloride) (PVC) in the melt was investigated in terms of changes in the thermal behaviour of PVC by studying the weight loss after 50 min at 180 °C, colour changes of the blend before and after aging for one week at 90 °C, the variation in glass transition temperature and the initial decomposition temperature. The results gave proof for the stabilizing role played by the investigated polyesters against the thermal degradation of PVC. The best results are obtained when PVC is mixed with 5% aliphatic polyesters rather than with aromatic ones. This is well illustrated not only from the increase in the initial decomposition temperature (IDT), but also from the decrease of % weight loss and from the lower extent of discolouration of PVC, which is a demand for the application of the polymer. It was also found that blending PVC with 5% of the four investigated polyesters before and after aging for one week at 90 °C gave better mechanical properties even than that of the unaged PVC blank.

Phenyl urea derivatives have been prepared and investigated as photostabilizers for rigid PVC by measuring the extent of weight loss (%), the amount of gel formation as well as the intrinsic viscosity of the soluble fractions of the degraded polymer. Moreover, the efficiency of these stabilizers was evaluated from the extent of discoloration of the degraded polymer in their presence. The results indicated a reasonable stabilizing effect of these derivatives when compared with the commercially used UV stabilizers: phenyl salicylate (Salol) and methanone, 2-hydroxy-4-(octyloxy)-phenyl-benzophenone. A synergistic effect is achieved when the phenyl urea derivatives are mixed with the UV absorbers in the ratio (75 : 25%), respectively. A radical mechanism is proposed to account for the stabilizing action of the products investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2217–2226, 2007

N-Phenyl-3-substituted 5-pyrazolone derivatives were investigated as organic photostabilizers for rigid poly(vinyl chloride) (PVC). Their stabilizing efficiency was evaluated by the determination of the weight loss of the polymer after irradiation for different periods and by the determination of the amount of gel formation as well as the intrinsic viscosity of the soluble fraction of the degraded polymer. Moreover, the efficiency was evaluated from the extent of the discoloration of the degraded polymer. This was attributed not only to the radical trapping potency of the pyrazolone derivatives, which intervened with the radical degradation species in the degradation process of PVC, but also to the blocking of the newly formed radical sites on the polymeric chains. Their stabilizing efficiencies were compared with those of phenyl salicylate and 2-hydroxy-4-(octyloxy)phenyl benzophenone, industrially known UV absorbers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1543–1555, 2006

Anthraquinone derivatives have been prepared and investigated as photo-stabilizers for rigid PVC by measuring the extent of weight loss (%), the amount of gel formation as well as the intrinsic viscosity of the soluble fractions of the degraded polymer. The results indicated a reasonable stabilizing effect of these derivatives compared with UV-commercially used stabilizers. A synergistic effect is achieved when the anthraquinone derivatives are mixed with UV-absorbers in a weight ratio of 75% of investigated organic stabilizer and 25% of reference stabilizer. A probable radical mechanism is proposed to account for the stabilizing action of the organic investigated materials.

Polymeric composites prepared from unsaturated polyester resin based on poly(1,2 propylene-maleate-o-carboxy phthalanilate) were used with styrene monomer (40% by weight) as a binder and alumina trihydrate (ATH) (Al2O3 · 3H2O) or clay as fillers. The effects of the type and concentration of the two fillers on the physical, chemical, mechanical, thermal, and electrical properties of the formed composites were studied. The fire retardant efficiency of the prepared composites was also investigated. The results indicated that the use of ATH filler reduces both the flammability and smoke density whereas Aswan clay increases the thermal stability. Both fillers enhance electrical characteristics of the formed composites as insulators when compared to the styrenated polyester resin used alone. The obtained polymeric composites would be excellent candidates for potential applications.

Modification of chitin by grafting with itaconic acid (IA) was carried out using potassium persulfate as redox initiator. In complimentary experiments, grafting was performed using γ-radiation. Grafting was confirmed by FTIR spectroscopy. The effect of monomer concentration, initiator concentration and copolymerization temperature on the percentage of grafting were studied. The effect of radiation dose was also investigated. Values for percentages of grafting of up to 300 % were reached. It was observed that the percentage of grafting increased with increasing monomer concentration and showed a tendency to level off at IA concentration of 0.1 mol l−1. The percentage of grafting increased with temperature up to 60 °C and then decreased. The solubility of the grafted chitin was studied in organic and inorganic solvents. The complexation of the grafted chitin with some cations, namely copper, nickel, cobalt, zinc and lead, was also investigated. The metal uptake was measured by UV spectroscopy. Thermogravimetric analysis of the grafted chitin was also studied. Copyright © 2004 Society of Chemical Industry

A new monomer (o-carboxy phthalanilic acid) was prepared by the reaction of o-aminobenzoic acid with phthalic anhydride. This monomer was condensed with different acids and glycols to prepare three unsaturated polyester resins namely, poly (1,2-propylene-maleate-o-carboxy phthalanilate) polyester I, poly (ethylene- maleate- o-carboxy phthalanilate) polyester II and poly (1,2-propylene-itaconate- o-carboxy phthalanilate) polyester III. Infrared (IR) and nuclear magnetic resonance (NMR) spectra were used qualitatively and quantitatively to elucidate the structure of the prepared polyester resins. These unsaturated polyester resins were found to cure with styrene at room temperature in the presence of methyl ethyl ketone peroxide (MEKP) as initiator and Co- naphthenate as accelerator. The effect of concentration of the initiator (MEKP) and the accelerator (Co-naphthenate) on the compressive strength values was studied. The effect of the type of glycol and the unsaturated acid in the styrenated polyester backbone on the chemical resistance, flammability, thermal stability, physical, electrical and weathering properties was also studied. It was found that the styrenated poly (1,2-propylene-maleate-o-carboxy phthalanilate) has the highest compressive strength value and the best chemical resistance and physical properties.

Comonomers of vinylimidazole (VI) and acrylic acid (AA) have been grafted onto Polypropylene (PP) films using γ-radiation. The effect of the comonomer composition on the percent graft was investigated. The reactivity ratio of the prepared copolymers was determined by conventional methods. IR spectroscopy, surface morphology, mechanical properties, dyeability, as well as thermal stability of the grafted samples were also studied.

The effect of mixing 2-benzimidazolyl- ω -phenylpropenylidineacetonitrile (BPAN) with each of the reference stabilizers: dibasic lead carbonate (DBLC), dibasic lead stearate (DBLS), barium–cadmium–zinc stearate (Ba–Cd–Zn stearate), or dibutyltin maleate (DBTM) on the stabilizing efficiency in thermal degradation of rigid PVC at 180 °C, in air, has been investigated. Mixing was effected in the range of 0–100 wt.% of BPAN relative to each of the reference stabilizers. The stabilizing efficiency was evaluated by measuring the length of the induction period ( T s ), the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination on the one hand, and the extent of discoloration of the degraded polymer samples on the other. The results show a true synergistic effect from the combination of BPAN with any of the reference stabilizers. Mixing of the stabilizers improves the T s values, decreases the rate of dehydrochlorination, and lowers the extent of discoloration of the polymer. The synergism reaches its maximum when the BPAN is mixed with either DBLS or Ba–Cd–Zn stearate in weight ratio of 25/75%, respectively. In case of DBLC or DBTM, the maximum synergism was attained when the stabilizers mixtures were in equivalent weight ratio (50/50%). The observed synergism may be attributed to the different mechanisms by which the investigated and the reference stabilizers work.

The effect of mixing p -chloro- N -phenylphthalimide ( p -Cl- N OPI) with the reference stabilizers: dibasic lead carbonate (DBLC), dibasic lead stearate (DBLS), barium–cadmium–zinc stearate (Ba–Cd–Zn stearate), n -octyltin mercaptide ( n -OTM) or dibutyltin maleate (DBTM) on the stabilizing efficiency in thermally degradation of rigid PVC at 180 °C, in air, has been investigated. Mixing was effected in the range of 0–100 wt.% of p -Cl- N OPI relative to the reference stabilizers. The stabilizing efficiency is evaluated by measuring the length of the induction period ( T s ), the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination on one hand, and the extent of discoloration of the degraded polymer samples on the other. The results reveal that mixing of the stabilizers improves the Ts values, decreases the rate of dehydrochlorination and lowers the extent of discoloration of the polymer. This improvement attains its maximum when the p -Cl- N OPI is mixed with any of DBLC, DBLS, Ba–Cd–Zn stearate or DBTM reference stabilizers in weight ratio of 25/75%, respectively. Mixing of p -Cl- N OPI with n -OTM is an exception, as maximum synergism was attained at equivalent weight ratio (50/50%).

Phenylurea and phenylthiourea derivatives have been investigated as thermal stabilizers or co-stabilizers for rigid PVC in air, at 180 °C. The results reveal the higher stabilizing potency of the investigated organic stabilizers as compared with commercial reference stabilizers, which is proved by their greater induction period values, but with higher dehydrochlorination rate at the later stages of degradation. Complexation of these materials with the chlorides of Ni 2+ and Cd 2+ greatly improved the induction period values, however the dehydrochlorination rate is only slightly improved. On the other hand, blending the investigated thermal stabilizers with some of the commercially known reference stabilizers in different proportions leads to a true synergistic effect. The induction period values and the degradation rate were remarkably improved. A probable mechanism for the stabilizing action of phenylurea and phenylthiourea derivatives has been proposed.

N-Benzoyl-N′-p-substituted phenylthiourea derivatives have been investigated as thermal stabilizers or co-stabilizers for rigid PVC at 180 °C in air. The results reveal the higher stabilizing potency of the investigated organic stabilizers as compared with some of the commercially known reference stabilizers, which is proved by their greater induction period values (Ts), during which no detectable amount of hydrogen chloride gas could be detected, but with higher dehydrochlorination rate at the later stages of degradation. Complexation of these materials with the chlorides of Ni2+ and Cd2+ improved greatly the induction period values, however the dehydrochlorination rate is only slightly improved. On the other hand, blending these thermal stabilizers with some of the commercially known reference stabilizers in different proportions leads to a true synergistic effect. The induction period values and the degradation rate were remarkably improved. A probable ionic mechanism for the stabilizing action of N-Benzoyl-N′-p-substituted phenylthiourea derivatives is proposed. The stabilizing efficiency is attributed to the replacement of the labile chloride ions on the PVC chains by a relatively more stable moiety of the stabilizer.

Crosslinked poly(vinyl alcohol) (PVA)/carboxymethyl chitosan (CMCh) nanocomposites were synthesized using terephthaloyl diisothiocyanate crosslinker, in the presence of montmorillonite (MMT), in different ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PVA hydrogels increased the swellability. Metal ion adsorption has also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non crosslinked CMCh. Antimicrobial activity was examined against Gram positive bacteria, against Gram negative bacteria, and also against fungi. Results indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation study was carried out in Simulated Body Fluid (SBF) for different time periods in order to find out degradation index (Di). Results showed that weight loss of most of the nanocomposites increased as a function of incubation time.

The graft copolymerization of N-phenylmaleimide and its p-hydroxy derivative onto cotton fabric using γ-radiation was studied. The effects of monomer concentration, dose rate, and irradiation time have been investigated. The surface topology, the x-ray diffraction, and the thermal stability of the modified fabric also were studied. In addition, the dyeing characteristics of the grafted fabrics when dyed with basic dyes together with the color fastness of these dyes towards UV radiation were investigated.

2-Benzimidazolylacetonitrile (BAN) and some of its conjugated unsaturated derivatives namely: 2-benzimidazolylbenzylidineacetonitrile (BBeAN), 2-benzimidazolyl-ω-phenylpropenylidineacetonitrile (BPAN) and 2-benzimidazolylbut-2-enylidineacetonitrile (BBuAN) have been investigated as organic thermal stabilizers for rigid PVC at 180 °C in air. Their stabilizing efficiencies are based on measuring the length of the induction period ( T s ), the period during which no detectable amounts of HCl gas could be observed, and also from the rate of dehydrochlorination as measured by the continuous potentiometric titration on the one hand, and the extent of discoloration of the degraded polymer samples on the other. The stabilizing efficiencies of the investigated stabilizers were compared with that of dibasic lead carbonate (DBLC), dibasic lead stearate (DBLS), barium–cadmium–zinc stearate (Ba–Cd–Zn stearate) and dibutyltin maleate (DBTM) which are commonly used industrial stabilizers. The results reveal the higher stabilizing efficiency of the investigated materials relative to the reference stabilizers concerning the T s values. However, the rate of dehydrochlorination at the later stages of degradation for PVC stabilized with the investigated stabilizers is found to be relatively higher than that in the presence of reference stabilizers. These experimental findings indicate that almost all the stabilizers actions are exhausted during the induction period. The stabilizing efficiencies of the investigated stabilizers can be attributed to the replacement of the labile chlorine atoms on the polymer chains by a relatively more thermally stable groups derived from the stabilizer. This substitution reaction proceeds most probably through a radical mechanism. Moreover, the results also reveal the effect of the extent of conjugated unsaturates in the organic stabilizer molecule. The stabilizing potency of the investigated materials increases with the extent of their conjugated unsaturation sites. On the other hand, the results also reveal that while the extent of discoloration of thermally degraded PVC in the presence of BPAN stabilizer is comparable with most of the investigated reference stabilizers, the other derivatives showed a relatively higher extent of discoloration.

N-Arylphthalimide derivatives have been investigated as thermal stabilizers for rigid poly(vinyl chloride) (PVC). Their stabilizing efficiencies compared with some conventional thermal stabilizers have been measured by the continuous potentiometric determination of the evolved hydrogen chloride gas from the degradation, and by the extent of discoloration of the degraded samples. The results reveal the greater stabilizing efficiencies of most of the investigated derivatives as compared with reference stabilizers. A mechanism for the stabilizing action of the investigated stabilizers is proposed.

Itaconic acid was grafted onto cellulose fibers using potassium persulfate as initiator. The effect of initiator concentration, monomer concentration and the reaction temperature on the grafting percentage has been investigated. The IR spectroscopy, X-ray diffraction, as well as the surface morphology of the grafted fibers were also studied. Moreover, the dyeing characteristics of the grafted fibers dyed with two basic dyes together with the color fastness of these dyes towards UV radiation was also investigated. The thermal stability of the grafted fibers was also studied using a thermogravimetric technique.

Cross-linked hydrogels of polyethylene glycol (PEG) and carboxymethyl chitosan (CMCh) were synthesized using a blending technique. Several analysis tools were used to characterize the physical and thermal properties of CMCh/PEG hydrogels, namely, Fourier transform infrared, scanning electron microscope, X-ray diffraction, and thermogravimetric analysis. Some applications were carried out for the prepared cross-linked hydrogels; swelling behavior of the CMCh/PEG hydrogels was studied in different buffered solutions and different salt solutions. Metal ions uptake was studied for CMCh/PEG hydrogels. The biological activity of CMCh/PEG towards Escherichia coli has been examined in this study.

A series of biodegradable polyurethanes (PUs) were synthesized from hydroxylated bacterial poly[(R)-3-hydroxybutyrate], P[(R)-HB]-diol, as crystallizable hard segment and hydroxyl-terminated synthetic poly[(R,S)-3-hydroxybutyrate), P[(R,S)-HB]-diol, as an amorphous soft segment, using 1,6-hexamethylene diisocyanate, as non-toxic connecting agent. The P[(R)-HB] content was varied from 30 to 70 wt %. The resulting copolymers were characterized by FT-IR, 1H-NMR, DSC, and TGA. The DSC data revealed that the melting of P[(R)-HB] segment increases with increasing its own content in the PUs. The cold and melt crystallization are enhanced with increasing P[(R)-HB] content. The TGA data revealed that the thermal decomposition mainly occurred via a single degradation step and the thermal stability slightly increased with increasing P[(R)-HB] content. The non-isothermal crystallization behavior of PU sample containing 40 wt % PHB with and without α-Chitin whiskers was studied using DSC, and their kinetics data were investigated via the Avrami, Ozawa, and Z.S. Mo methods, respectively. Crystallization activation energy was estimated using Kissinger's method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40784.

Carboxymethyl chitosan (CMCh)–silver nanoparticle (Ag) hydrogels with high antibacterial activity against three Gram +ve bacteria ( Staphylococcus aureus , Bacillus subtilis and Streptococcus faecalis ), three Gram −ve bacteria ( Escherichia coli , Pseudomonas aeruginosa and Neisseria gonorrhoeae ) and a Candida albicans fungus were prepared. The in situ preparation reaction involved crosslinking of CMCh with epichlorohydrin in alkaline medium containing silver nitrate to yield silver nanoparticles loaded CMCh hydrogel giving pale brown or darker hydrogels when the silver content increases. FTIR spectroscopy, SEM and TEM were done for the prepared hydrogels. Silver nanoparticles hydrogels exhibited higher antimicrobial activity than virgin CMCh. TEM analysis showed the small size of the prepared hydrogels to be in the range of 9–16 nm in size.

Crotonal thiobarbituric acid (CTBA) and cinnamal thiobarbituric acid (CiTBA) have been investigated as thermal stabilizers for rigid poly (vinyl chloride) (PVC) at 180°C in air. Their stabilizing efficiency is evaluated by measuring the length of the induction period ( T s ), the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric titration on one hand and the extent of discoloration of the degraded polymer on the other. The results reveal the higher stabilizing efficiency of the investigated materials as compared with industrially used thermal stabilizers such as dibasic lead carbonate (DBLC), dibasic lead stearate (DBLS), n -octyl tin mercaptide ( n -OTM), dibutyl tin maleate (DBTM) and barium–cadmium–zinc stearate (Ba–Cd–Zn stearate). This is well illustrated by the longer T s values, and by the lower rates both of dehydrochlorination and discoloration of the polymer during degradation relative to those of the reference stabilizers. A radical mechanism for the stabilizing effect of the investigated materials is suggested. The results indicate the important role played by the extent of conjugation in thiobarbituric acid derivatives on the stabilizing efficiency of the stabilizers. The stabilizing potency of the stabilizer increases with the extent of conjugation. The effect of blending CiTBA with either of the reference stabilizers on the stabilizing efficiency of the thermally degraded rigid PVC has been also investigated. The results reveal that mixing of the stabilizers improve both the T s values, the rate of dehydrochlorination and the extent of discoloration. This improvement attains its maximum when both the investigated and the reference stabilizers are taken in equivalent weight ratios.

1-Cyanoethanoyl-4-acryloylthiosemicarbazide (CEATS) was synthesized for the first time as a new chelating monomer. Its structure was confirmed by both elemental and spectral analyses. Radical polymerization and copolymerization of CEATS was been carried out in dimethylformamide (DMF) in the presence of azobisisobutyronitrile (AIBN) as an initiator. Kinetic studies for the polymerization behavior of CEATS were performed. The complex formation of the CEATS monomer and polymer (PCEATS) with Cu II cation was investigated and its stability constant determined. The rate of copolymerization of CEATS with some conventional monomers, namely vinyl acetate, methyl methacrylate and acrylonitrile, was measured as a function of the mole fraction of the monomers. The reactivity ratios (r1, r2) for the various copolymer systems investigated together with the Q and e values of the CEATS monomer were determined. Moreover, the thermal gravimetric analysis of the prepared polymers and their copolymers with acrylonitrile were also studied.

Barbituric acid (BA) and thiobarbituric acid (TBA) have been investigated as thermal stabilizers for rigid poly(vinyl chloride) (PVC) at 180°C, in air. The efficiency of these compounds as thermal stabilizers was evaluated by measuring the length of the induction period ( T s ), during which no detectable amount of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric titration on one hand, and the extent of discoloration of the degraded polymer on the other. The stabilizing efficiencies were compared with that of dibasic lead carbonate (DBLC), dibasic lead stearate (DBLS), barium–cadmium–zinc stearate (Ba–Cd–Zn stearate), n -octyl tin mercaptide ( n -OTM) and dibutyl tin maleate (DBTM). With the exception of DBTM reference stabilizer which shows a comparable stabilizing efficiency with BA and TBA, the investigated organic stabilizers exhibit a greater efficiency than those of all other reference stabilizers. Moreover, they impart better color stability to the degraded samples. A radical mechanism for the stabilizing action is suggested. The stabilizing efficiency is attributed to the replacement of the labile chlorine atoms on the PVC chains by a relatively more stable moiety of the stabilizer. This disrupts the formation of conjugated double bonds, which are responsible for the discoloration.

Benzal thiobarbituric acid (BTBA) and two of its derivatives: para -methoxy benzal thiobarbituric acid ( p -MeO-BTBA) and para -chloro benzal thiobarbituric acid ( p -Cl-BTBA) have been investigated as thermal stabilizers for rigid PVC at 180°C, in air. Their stabilizing efficiency is based on measuring the rate of dehydrochlorination and the extent of discoloration of the degraded polymer. The results reveal the higher stabilizing efficiency of the investigated materials as thermal stabilizers for rigid PVC as compared with the industrially used thermal stabilizers: dibasic lead carbonate (DBLC), dibasic lead stearate (DBLS), n -octyl tin mercaptide ( n -OTM), dibulyl tin maleate (DBTM) and barium–cadmium–zinc stearate (Ba–Cd–Zn stearate). This is well illustrated by the longer induction period ( T s ) values and by the lower rate of dehydrochlorination. The stabilization efficiency is affected by the nature of the substituent found in the phenyl ring of the BTBA derivatives. Moreover, it was found that these materials lower the extent of discoloration of the polymer during degradation as compared with the reference stabilizers. A radical mechanism for the stabilizing effect of BTBA and its derivatives is proposed. The effect of blending p -Cl-BTBA with either of the reference stabilizers on the stabilizing efficiency of the thermally degraded rigid PVC has been also investigated. The results reveal that mixing of the stabilizers improves both the T s values, the rate of dehydrochloration and the extent of discoloration. This improvement attains its maximum when both the investigated and the reference stabilizers are taken in equivalent weight ratio.

Binary blends of poly(vinyl chloride) (PVC) and poly(vinyl butyral) (PVB) have been prepared by solution blending. The physical and mechanical properties of the blends are studied usind differential scanning calorimetry (DSC), thermogravimetry (TG) and tensile testing. The DSC results showed a high degree of molecular mixing of the two polymers. All the blends exhibited one major glass transition temperature (Tg) whose position on the temperature scale is lowered with increasing level of PVB. The thermal stability of the blends was found to increase with the increase in the PVB content in the blend. This is illustrated by both TG and rate of thermal dehydrochlorination of various investigated blends.

1-Cyanoethanoyl-4-acryloyl thiosemicarbazide (CEATS) and its metal complexes with Sn 2+ , Cd 2+ , Co 2+ ions have been investigated as thermal stabilizers for rigid poly(vinyl chloride). The results reveal that the stabilizing efficiency of CEATS is comparable to that of the commonly used industrial stabilizers, while the stabilizing efficiencies of CEATS complexes greatly exceed that of the parent molecule. CEATS as a co-stabilizer with reference stabilizers namely Cd–Ba stearates, dibutyl tin maleate, or basic lead sulfate led to a synergistic effect. A probable mechanism expressing the interaction of CEATS molecule with metal salts stabilizers has been proposed.

N-Acryloyl,N′-cyanoacetohydrazide (ACAH) and its complexes with some metal ions have been investigated as thermal stabilizers for rigid poly(vinyl chloride) (PVC). Their stabilizing efficiencies have been measured by the continuous potentiometric determination of the evolved hydrogen chloride gas from the degradation process and by the extent of discoloration of the degraded samples compared with some conventional thermal stabilizers. The efficiency of blending ACAH with conventional thermal stabilizers has been investigated. A probable mechanism for the stabilizing action of ACAH is also proposed. © 1998 SCI.

Radical Polymerization and Copolymerization Behavior of N -Acryloyl N ′-Cyanoacetohydrazide

Polypropylene (PP) films were grafted with N-phenylmaleimide using γ-radiation. The effect of both monomer concentration and dose rate on the degree of grafting was measured. Characterization of the grafted PP films included IR spectroscopy, X-ray spectroscopy, electrical conductivity, mechanical properties and thermal stability has been studied. © of SCI.