Abir S. Abdel-Naby

1-Cyanoethanoyl-4-acryloyl thiosemicarbazide and its metal complexes as thermal stabilizers for rigid poly(vinyl chloride)

Abstract 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.

Cyanoguanidine and its complexes as thermal stabilizers for rigid poly(vinyl chloride)

Abstract Cyanoguanidine and its complexes with cadmium and zinc have been investigated as thermal stabilizers for rigid PVC, at 180°C, in air. The results reveal the higher stabilizing efficiency of the investigated materials as shown by the longer induction periods obtained in their presence relative to those using dibutyl tin maleate, cadmium-barium stearate and basic lead carbonate, which are commonly used industrial stabilizers. The stabilizing efficiencies of the complex derivatives are higher than those of the parent cyanoguanidine. A synergistic effect is observed when cyanoguanidine is blended in various molar ratios with either of the soap stabilizers. The synergistic effect is probably due to the ability of cyanoguanidine for in-situ complexation with the metal chlorides which result as stabilization by-products, thus protecting the polymer from their deleterious accelerating degradative effect. An ionic mechanism for the stabilizing effect of cyanoguanidine and its derivatives is proposed.

Inhibition of the degradation of poly(vinyl chloride) by its modification with 5‐pyrimidine carbonitrile (1,2,3,4‐ tetrahydro‐4‐oxo‐6‐phenyl‐2‐thioxo)

The reaction of poly(vinyl chloride) (PVC) with 5-pyrimidine carbonitrile (1,2,3,4-tetrahydro-4-oxo-6-phenyl-2-thioxo) has been studied. The thermal stability of the modified polymer is improved markedly compared with the unmodified polymer. The stability improvement is attributed to the replacement of the labile chlorine atoms by more stable thio groups. The modified polymer also showed a lower extent of discoloration against ultraviolet rays compared with the unmodified PVC.

Improvement of the thermal and mechanical properties of poly (vinyl chloride) in presence of poly (ethylene succinate)

Abstract Binary blends of poly (vinyl chloride) (PVC) and poly (ethylene succinate) (PES) have been prepared by solution blending aimed at the improvement of thermal and mechanical properties. Thermal properties of the blends were studied using scanning calorimetry (DSC), thermogravimetry (TG) and potentiometric rate of dehydrochlorination. The increase of the PES content in the blend leads to thermal stability of the blend as shown from the thermogravimetry and the rate of dehydrochlorination results. All blends exhibited one major glass transition temperature (Tg) whose position on the temperature scale is lowered with increasing level of PES. Mechanical properties of various blends of the two polymers were also measured.

Stabilization of poly(vinyl chloride) against laser radiation with ethyl-N-phenylmaleimide-4-carboxylate

Abstract Ethyl- N -phenylmaleimide-4-carboxylate (ENPMC), has been studied as a stabilizer for poly (vinyl chloride), (PVC) against laser radiation. The effects of ENPMC concentration and laser radiation dose on the thermal properties of the polymer have been studied. The results reveal a great improvement in the thermal stability of the polymer in the presence of the organic material. This thermal stability is shown by both thermal gravimetric analysis and the rate of dehydrochlorination of the polymer. The effective concentration for the protection of the polymer against thermal degradation was found to be 10 mmol ENPMC per 100 g PVC. The effect of laser pulses on the polymer stabilized with this concentration of ENPMC have been studied using UV spectroscopy, infra red spectroscopy and thermal gravimetric analysis

Chemical modification of cellulose acetate by N-(phenyl amino) maleimides: Characterization and properties

Cellulose acetate (CA) was modified using N-(phenyl amino) maleimides (R-APhM) where, RH or 4-NO2. The structure of the modified polymer was characterized by (13)C-NMR. The chemical modification is based on the reaction between the acetyl group of the glucopyranose ring in cellulose acetate and the proton of the amino group in N-(phenyl amino) maleimide molecule. The thermal gravimetry (TGA) was used to investigate the thermal stability of the modified polymeric samples. The modified cellulose acetate by 4-nitro (phenyl amino) maleimide (CA/4-NO2APhM) exhibits the highest thermal stability as compared to the N-(phenyl amino) maleimide (CA/APhM) and the unmodified CA. The crystallinity and morphology of the modified polymeric samples were investigated using X-ray diffraction (XRD) and emission scanning electron microscope (ESEM), respectively. The presence of N-(phenyl amino) maleimide moieties in the cellulose acetate matrix improved its mechanical property. Also, the organic nature of (R-APhM) moieties inside CA matrix reduced its wettability.

Structure and optical investigation of the effect of laser radiation in stabilized poly (vinyl chloride)

Structure and optical property studies using IR & UV spectroscopy, refractive index measurement and X-ray diffraction were performed on poly (vinyl chloride), PVC, stabilized by para-ethyl carboxy N-phenyl maleimide (PEC-NPMI) additive. The effect of addition of the stabilizer PEC-NPMI, with different concentrations, was studied. The results indicate that the addition of PEC-NPMI with 0.01 r g/1 r g PVC enhances the isotropic nature of the PVC polymer. Furthermore the effect of laser radiation on the optical properties of the 0.01 r g PEC-NPMI/1 r g PVC polymer was studied. The study shows that the PVC stabilized with 0.01 r g PEC-NPMI/1 r g PVC and irradiated with 4.27 r J/cm 2 infrared laser radiation is most suitable for applications requiring PVC of high absorbance value in the IR and UV regions.

Cellulose acetate blends with acrylonitrile/ N -phenyl maleimide copolymers morphological and thermal properties

Cellulose acetate (CA) was blended in different compositions with various acrylonitrile-N-halo phenyl maleimide (AN-XPhM) copolymers to improve the thermal and mechanical properties of cellulose acetate. The structure, morphology, thermal stability, and crystallinity of the blend films were characterized by infrared spectroscopy, scanning electron micrographs, thermogravimetry/differential thermal analysis, differential scanning calorimetry, and X-ray diffraction. The results revealed that the thermal stability was improved by the increase in AN-XPhM content, irrespective of the type of the N-halo phenyl maleimide. The CA/AN-4BrPhM blend films possessed the highest thermal stability compared to the other CA/AN-XPhM blend films. Blending CA with AN-4BrPhM yielded the most homogeneous blend films, irrespective of the composition ratio. The mechanical properties of various compositions of the CA/AN-4BrPhM blend films were also discussed.

Investigation of the effect of gamma rays on electrical properties of chlorinated poly (vinyl chloride)

Dielectric constant, dielectric loss and AC conductivity were measured, in the frequency range 100 Hz to 5 MHz in chlorinated poly (vinyl chloride) (CPVC) before and after exposure to gamma irradiation at doses between 5.0 KGy and 50.0 KGy. The frequency dependencies of ε′, ε″ and σAC at 30 °C were investigated. A relaxation peak in the dielectric loss and a corresponding step in the dielectric constant have been observed, in the frequency ranges 103 Hz to 104 Hz. The dielectric constant ε′, dielectric loss ε″ and AC conductivity σAC are also found to increase at heating up to 100 °C. In addition the effect of gamma irradiation on the frequency dependencies of ε′, ε″ and σAC was measured at room temperature. The gamma irradiation leads to an increase in the efficiency of soft segments. Furthermore, the DC electrical conductivity of both the irradiated and non-irradiated samples was investigated. The induced electrical conductivity and the activation energy were measured, at various temperatures, as a function of gamma dose. It was found that the gamma radiation has a definite effect on the DC conductivity of the CPVC polymer.

Poly(vinyl chloride) blend with biodegradable cellulose acetate in presence of N-(phenyl amino) maleimides

Wider plastic applications of poly(vinyl chloride) (PVC) has raised serious problem to the environment. Since (PVC) waste products resist biodegradation and persist in the environment for longer time. The object of this study is to blend (PVC) with biodegradable cellulose acetate to thermally support the polymer during the molding process as well as to enhance the biodegradability of (PVC) waste products. Blending of poly(vinyl chloride) and cellulose acetate (CA) in presence of N-(phenyl amino) maleimides (R-PhAM) where (R=H, 4-NO2) led to improvement in the thermal stability of the blend film at high temperatures as shown from the high values of initial decomposition temperature (To) determined from their thermogravimetry (TG) curves. Also, blending (PVC) with (CA) led to improvement in the mechanical properties of the blend films as compared to (PVC). The crystalline regions of cellulose acetate enhanced the elasticity of the blend films as shown from their high Youngs modulus values.