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Journal Article
El.shafee, E., M. Zaki, and G. R. Saad, "Annealing of poly(trimethylene terephthalate)/polycarbonate blends", Journal of Polymer Research, vol. 16, issue 4, pp. 317 - 327, 2009. AbstractWebsite

A blend of poly(trimethylene terephthalate) (PTT) and polycarbonate with a weight ratio of 50/50 was studied by means of differential scanning calorimetry (DSC) and dielectric spectroscopy (DS) after melt annealing that enables transesterification. The DSC results show that with increasing the residence time in the melt, the melting temperature and the heat of fusion of PTT crystals decrease. Prolonged thermal treatment at 300 °C gives rise to a copolymer that no longer reveals melting or crystallization. Additional annealing of such samples below the melting temperature of PTT results in restoration of the crystallization ability. The amorphous phase dynamics is studied by means of DS demonstrating that the glass transition relaxations are very sensitive to the crystallinity changes. The random copolymer is characterized by only one α-relaxation indicating a more or less homogeneous amorphous phase. In contrast to this, the physical blend and the block copolymers show two α-relaxation processes attributed to the existence of two amorphous fractions. Analysis of the relaxation process in terms of Vogel-Fucher-Tammann- Hesse model reveals a correlation between the fragility parameter and the extent of trans-reaction. The crystallization kinetics of the blocky copolymer determined from the changes of the dielectric constant with time are discussed and compared with pure PTT. © 2008 Springer Science+Business Media B.V.

Saad, G. R., and H. Seliger, "Biodegradable copolymers based on bacterial Poly((R)-3-hydroxybutyrate): Thermal and mechanical properties and biodegradation behaviour", Polymer Degradation and Stability, vol. 83, issue 1, pp. 101 - 110, 2004. AbstractWebsite

Two series of poly(ester-urethane) block copolymers were synthesized from bacterial telechelics, hydroxylated poly[(R)-3-hydroxybutyrate] (PHB-diol), as hard segments, and either poly(butylene glycol adipate)-diol (PBA-diol) or poly(diethylene glycol adipate)-diol (PDEGA-diol), as soft segments, using 1,6-hexamethylene diisocyanate as a non-toxic connecting agent. The content of PHB hard segments systematically varied from 10 to 60 wt.%. The synthesized materials were characterized by 1H NMR, GPC, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, and tensile properties. The crystallization characteristics, reflecting the segmented properties of the synthesized copolymers, are discussed. For poly(ester-urethane)s, based on PHB-diol and PBA-diol, with PHB content less than 50 wt.%, both PBA and PHB crystalline phases, were detected. In contrast, in poly(ester-urethane)s, derived from PHB-diol and PDEGA-diol, only one crystalline phase, corresponding to the PHB hard segments, was observed. The thermogravimetric results of the prepared copolymers showed three-step decomposition assigned to the thermal degradation of PHB hard, PBA or PDEGA soft blocks, and urethane linkage, respectively. The tensile properties indicated that the tensile strength and elongation at the break points of poly(ester-urethane)s, derived from PHB and PBA, are greater than those prepared from PHB and PDEGA. The biodegradability was studied in compost-derived culture. The extent of mineralization was dependent on the copolymer composition. At a comparable incubation time, the copolymers containing 50 wt.% PHB were mineralized to an extent similar to that of the PHB homopolymer. © 2003 Elsevier Ltd. All rights reserved.

Saad, G. R., T. M. Khalil, and M. W. Sabaa, "Biodegradable poly(ester-urethane)s based on poly[(R)-3-hydroxybutyrate] and poly(ε-caprolactone) blocks: Thermal, mechanical and biodegradation behaviour", Eurasian Chemico-Technological Journal, vol. 9, issue 3, pp. 231 - 242, 2007. AbstractWebsite

α-ω-Dihydroxy-terminated poly[(R)-3-hydroxybutyrate] (PBB-diol) (Mn - 4800) was synthesized by transesterification of the corresponding PHB homopolymer with 1,4-butanediol in presence of p-toluenesulfanic acid. It was subsequently combined with poly(ε-caprolactone)-diols (PCL-diols) (Mn - 1260 and 2200) acting as soft segment via 1,6-hexamethylene diisocyanate to high molecular weight poly(esterurethane)s. The content of PHB acting as hard segments systematically varied from ∼20 to 60 wt.%. The synthesized materials were characterized by FTIR, 1H-NMF, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile properties. In the case of segmented poly(ester-urethane)s, those samples obtained from PCL (Mn - 1260) showed an increase in Tg's with increasing PHB content, indicating some extent of PCL/PHB segment phase mixing. All of the investigated copolymers were semicrystalline with Tm of PCL phase varying from 39-47°C and PHB phase varying from 141-150°C. The TGA analysis of the investigated copolymers showed three distinct weight loss steps assigned to the thermal degradation of PHB, PCL and urethane linkage with increasing temperature, respectively. As for mechanical tensile, it was found that the ultimate strength and elongation at the breakpoint decrease with increasing PHB content. The biodegradability was studied in active soil. The results showed that the biodegradation rate of the investigated copolymers increases with increasing PHB content. © 2007 al-Farabi Kazakh National University.

Saad, G. R., "Blends of bacterial poly[(R)-3-hydroxybutyrate] with oligo[(R,S)-3-hydroxybutyrate]-diol", Polymer International, vol. 51, issue 4, pp. 338 - 348, 2002. AbstractWebsite

The miscibility, melting and crystallization behaviour of poly[(R)-3-hydroxybutyrate], PHB, and oligo[(R,S)-3-hydroxybutyrate]-diol, oligo-HB, blends have been investigated by differential scanning calorimetry: thermograms of blends containing up to 60 wt% oligo-HB showed behaviour characteristic of single-phase amorphous glasses with a composition dependent glass transition, Tg, and a depression in the equilibrium melting temperature of PHB. The negative value of the interaction parameter, determined from the equilibrium melting depression, confirms miscibility between blend components. In parallel studies, glass transition relaxations of different meltcrystallized polymer blends containing 0-20 wt% oligo-HB were dielectrically investigated between -70°C and 120°C in the 100 Hz to 50 kHz range. The results revealed the existence of a single α-relaxation process for blends, indicating the miscibility between amorphous fractions of PHB and oligo-HB. © 2002 Society of Chemical Industry.

Saad, G. R., "Calorimetric and Dielectric Study of the Segmented Biodegradable Poly(ester-urethane)s Based on Bacterial Poly[(R)-3-hydroxybutyrate]", Macromolecular Bioscience, vol. 1, issue 9, pp. 387 - 396, 2001. AbstractWebsite

Two series of segmented poly(ester-urethane)s were synthesized from bacterial poly[(R)-3-hydroxybutyrate]-diol (PHB-diol), as hard segments, and either poly(ε-caprolactone)-diol (PCL-diol) or poly(butylene adipate)-diol (PBA-diol), as soft segments, using 1,6-hexamethylene diisocyanate as a chain extender. The hard-segment content varied from 0 to 50 wt.-%. These material were characterized using 1H NMR spectroscopy and GPC. The polymers obtained were investigated calorimetrically and dielectrically. DSC showed that the Tg of either the PCL or PBA soft segments are shifted to higher temperatures with increasing PHB hard-segment content, revealing that either the PCL or PBA are mixed with small amounts of PHB in the amorphous domains. The results also showed that the crystallization of soft or hard segments was physically constrained by the microstructure of the other crystalline phase, which results in a decrease in the degree of crystallinity of either the soft or hard segments upon increase of the other component. The dielectric spectra of poly(ester-urethane)s, based on PCL and PHB, showed two primary relaxation processes, designate as aS and aH, which correspond to glass-rubber transitions of PCL soft and PHB hard segments, respectively. Whereas in the case of other poly(ester-urethane)s, derived from PBA and PHB, only one relaxation process was observed, which broadens and shifts to higher temperature with increasing PHB hard-segment content. It was concluded from these results that our investigated materials exhibit micro-phase separation of the hard and soft segments in the amorphous domains.

Saad, G. R., "Calorimetric and dielectric study of the segmented biodegradable poly(ester-urethane)s based on bacterial poly[(R)-3-hydroxybutyrate]", Macromolecular Chemistry and Physics, vol. 202, issue 18, pp. 387 - 396, 2001. AbstractWebsite

Two series of segmented poly(ester-urethane)s were synthesized from bacterial poly[(R)-3-hydroxybutyrate]-diol (PHB-diol), as hard segments, and either poly(ε-caprolactone)-diol (PCL-diol) or poly(butylene adipate)-diol (PBA-diol), as soft segments, using 1,6-hexamethylene diisocyanate as a chain extender. The hard-segment content varied from 0 to 50 wt.-%. These materials were characterized using 1H NMR spectroscopy and GPC. The polymers obtained were investigated calorimetrically and dielectrically. DSC showed that the Tg of either the PCL or PBA soft segments are shifted to higher temperatures with increasing PHB hard-segment content, revealing that either the PCL or PBA are mixed with small amounts of PHB in the amorphous domains. The results showed that the crystallization of soft or hard segments was physically constrained by the micro-structure of the other crystalline phase, which results in a decrease in the degree of crystallinity of either the soft or hard segments upon increase of the other component. The dielectric spectra of poly(ester-urethane)s, based on PCL and PHB, showed two primary relaxation processes, designated as αs and αH, which correspond to glass-rubber transitions of PCL soft and PHB hard segments, respectively. Whereas in the case of other poly(ester-urethane)s, derived from PBA and PHB, only one relaxation process was observed, which broadens and shifts to higher temperature with increasing PHB hard-segment content. It was concluded from these results that our investigated materials exhibit micro-phase separation of the hard and soft segment in the amorphous domains.

El Shafee, E., G. R. Saad, and M. Zaki, "Calorimetric and dielectric study on poly(trimethylene terephthalate)/ polycarbonate blends", Journal of Polymer Research, vol. 15, issue 1, pp. 47 - 58, 2008. AbstractWebsite

Poly(trimethylene terephthalate) (PTT)/polycarbonate (PC) blends with different compositions were prepared by melt blending. The miscibility and phase behavior of melt-quenched and cold-crystallized blends were studied using differential scanning calorimetry (DSC) and dielectric relaxation spectroscopy. The blends of all compositions display only one glass transition (T g ) in both states. The melting temperature and the crystallinity of PTT in the blend decrease with increasing PC content. The dielectric results for the melt-quenched blends, for PC content up to 60 wt.%, exhibited two merged relaxation peaks during the heating scan; the lower temperature relaxation peak represent the normal glass-transition (α) relaxation of the mixed amorphous phase and the higher temperature relaxation due to the new-constrained mixed amorphous phase after crystallization. Cold-crystallized blends displayed only one glass transition α-relaxation whose temperatures varied with composition in manner similar to that observed by DSC. The dielectric α-relaxation of cold crystallized blends has been analyzed. Parameters relating to relaxation broadening, dielectric relaxation strength, and activation energy were quantified and were found to be composition dependent. The PTT/PC blends could be considered as two-phase system, a crystalline PTT phase and a mixed amorphous phase consisting of a miscible mixture of the two polymers. However, the crystallinity was only detected for blends containing greater than 40 wt.% PTT. © 2007 Springer Science+Business Media B.V.

Hamed, A. A., G. R. Saad, I. A. Abdelhamid, A. H. M. Elwahy, M. M. Abdel-Aziz, and M. Z. Elsabee, "Chitosan Schiff bases-based polyelectrolyte complexes with graphene quantum dots and their prospective biomedical applications", Journal of Radioanalytical and Nuclear Chemistry, vol. 208, pp. 1029-1045, 2022.
Hanna, D. H., V. F. Lotfy, A. H. Basta, and G. R. Saad, "Comparative Evaluation for Controlling Release of Niacin from Protein- and Cellulose-Chitosan Based Hydrogels", International Journal of Biological Macromolecules , vol. 150, pp. .228-237, 2020.
Mikhael, M. G., S. M. Mokhtar, G. R. Saad, M. M. Naoum, and M. Z. Elsabee, "Copolymerization and interaction of acrylonitrile and indene", Journal of Polymer Science Part A: Polymer Chemistry, vol. 27, issue 1, pp. 185 - 191, 1989. AbstractWebsite

The donor–acceptor interaction of acrylonitrile (AN) with indene (In) has been investigated by means of ultraviolet spectroscopy and dielectric polarization measurements. The latter method yielded a value of 0.5 for the association constant of the charge‐transfer‐complex (CTC) and a 4.02 D for its dipole moment. The copolymerization of the two monomers was characterized by a tendency towards alternation when conducted in the bulk. This might be due to the participation of a weak CTC in the process of copolymerization. However, this tendency disappeared in polar solvents such as DMF. Copyright © 1989 John Wiley & Sons, Inc.

Naguib, H. F., G. R. Saad, and M. Z. Elsabeé, "Copolymerization of bromophenylmaleimide with ethyl or butyl methacrylate", Polymer International, vol. 52, issue 7, pp. 1217 - 1221, 2003. AbstractWebsite

N-p-Bromophenylmaleimide (BrPMI) does not polymerize in solution by conventional free radical mechanism. However, it readily polymerized in bulk when mixed with a free radical initiator and heated in a microwave oven for 7-8 min. Copolymerization of ethyl methacrylate or butyl methacrylate with BrPMI was conducted in dioxane. The copolymers were characterized by IR and 1H NMR spectroscopy and gel permeation chromatography. The monomer reactivity ratios were calculated by a non-linear least-square analysis. Thermal analysis indicated a great improvement in thermal stability of the copolymers compared with the methacrylate homopolymers. BrPMI was also polymerized in bulk in the DSC pan, which allowed the calculation of the activation energy of its polymerization. © 2003 Society of Chemical Industry.

Saad, G. R., H. E. Salama, N. A. Mohamed, and M. W. Sabaa, "Crystallization and thermal properties of biodegradable polyurethanes based on poly[(R)-3-hydroxybutyrate] and their composites with chitin whiskers", Journal of Applied Polymer Science, vol. 131, issue 18, pp. 9395 - 9407, 2014. AbstractWebsite

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. Copyright © 2014 Wiley Periodicals, Inc.

Saad, G. R., H. M. Abdallah, M. S. A. Aziz, N. A. Mohamed, and M. W. Sabaa, "Cure kinetics and thermal stability of maleimide modified epoxy TGIC/CPE powder coating system", Thermochimica Acta, vol. 617, pp. 191 - 199, 2015. AbstractWebsite

The curing kinetics of the modified triglycidyl isocyanurate (TGIC) with various content of N-phenylmaleimido group and carboxylated polyester (CPE) was investigated using dynamic differential scanning calorimetry (DSC). The curing kinetic behavior was well described by Šesták-Berggren (SB (m, n)) model. The m order of the curing reaction was varied from 0.229 to 0.356 and n order varied from 1.278 to 2.035, depending on the PMI content. In addition, the isoconversional method of Kissinger-Akahira-Sunose (KAS) was applied to correlate the activation energy (Ea) with the extent of cure. The obtained Ea increased with increasing phenyl maleimide content. As α increases, Ea declined up to α 0.3, then remained almost constant for α 0.3-0.8, and finally increased until completion of reaction, indicating complex reaction mechanism. The thermal stability of the cured modified TGIC/CPE was enhanced with incorporation of phenyl maleimide. © 2015 Elsevier B.V. All rights reserved.

Saad, G. R., A. A. Ezz, and H. A. Ahmed, "Cure kinetics, thermal stability, and dielectric properties of epoxy/barium ferrite/polyaniline composites", Thermochimica Acta, vol. 599, pp. 84 - 94, 2015. AbstractWebsite

Barium ferrite/polyaniline composites (Ba ferrite/PANI) were synthesized using in situ polymerization of different BaFe12O19/aniline weight ratios and dispersed in diglycidyl ether bisphenol-A/carboxylated polyester (DGEBA/CPE) hybrid powder coating system. The effects of heating rate, Ba ferrite/PANI compositions and their loading level on the curing process was investigated by differential scanning calorimetry (DSC) in the dynamic mode. The activation energy of the cure reaction was examined utilizing Kissinger-Akahira-Sunose (KAS) method. It was found that the activation energy of the cure reaction of the epoxy increases with increasing the content of the filler. The dielectric properties were studied using dielectric relaxation analysis over a range of frequency (0.2-100 kHz) at 30 °C. The obtained dielectric data were analyzed using complex permittivity and modulus formalisms, depending on the concentration of filler in the epoxy matrix. ©2014 Elsevier B.V. All rights reserved.

Omer, A. M., T. M. Tamer, A. El Monem, S. A. Elmoaty, M. A. El Fatah, and G. R. Saad, "Development of PVC membranes with clove oil as plasticizer for blood bag applications", Journal of Applied Pharmaceutical Science, vol. 6, issue 7, pp. 85 - 93, 2016. AbstractWebsite

In the present study, Antimicrobial PVC films containing different amounts of clove oil as a plasticizer were prepared using traditional casting method. The physical and mechanical properties of the plasticized PVC membranes e.g. surface wettability were investigated. The increase of clove oil content demonstrated an increase in surface hydrophilicity and elongation to break the film. The thermogravimetric analysis revealed a decrease of polymer thermal stability by increasing clove oil concentration. The antibacterial activities against four different bacterial strains (two-gram positive: Staphylococcus aureus and Bacillus cereus & two-gram negative: Pseudomonas aeruginosa and Escherichia coli) were promoted by addition of clove oil. Although the natural source of clove oil, the bio-evaluation of plasticized membranes showed an increase in hemolysis percent (%) and thrombus weight. It can be concluded that the addition of clove to PVC need to further studies for applying in blood bags. © 2016 Ahmed M. Omer et al.

El-Shafee, E., and G. R. Saad, "Dielectric analysis of poly(vinyl chloride) films doped with cobalt(II) chloride", Polymer Degradation and Stability, vol. 41, issue 1, pp. 25 - 29, 1993. AbstractWebsite

The dielectric behaviour of solution-grown thin films of poly(vinyl chloride) containing cobalt(II) chloride as dopant was investigated within the temperature range 20-120°C and a 1-100 kHz frequency band. When correction was made for a conduction effect at low frequency, a high-temperature glass-transition relaxation process was observed in addition to the ordinary glass-transition process of pure PVC. The former was thus considered to be a cluster-ionic transition process which might be due to a phase-separation behaviour. The effect of moisture uptake by the doped films on the electrical properties is discussed. © 1993.

Saad, G. R., E. El-Shafee, and M. W. Sabaa, "Dielectric and mechanical properties in the photodegradation of poly(vinyl butyral) films", Polymer Degradation and Stability, vol. 47, issue 2, pp. 209 - 215, 1995. AbstractWebsite

The dielectric behaviour of unirradiated and irradiated PVB films, using UV radiation, was investigated as a function of temperature and frequency. The results obtained are discussed in terms of the dielectric parameters εmaxH, Δε, β and ΔE. These experimental results, in combination with the temperature dependence of dynamic mechanical measurements in the tensile mode and with d.s.c measurements, show that during UV irradiation of PVB, besides other changes, cross-linking predominates. A mechanism of photodegradation has been proposed and is supported by gel content determination and IR spectra. © 1995.

Saad, G. R., "Dielectric behaviour of cyanoethylated cellulose", Polymer International, vol. 34, issue 4, pp. 411 - 415, 1994. AbstractWebsite

The dielectric characteristics of cyanoethylated cellulose samples having different degrees of substitution have been investigated at different frequencies from 0.1 to 10 KHz and at temperatures from −40°C to 180°C. Two relaxation processes, designated as α and β in order of decreasing temperature, were recognised. The low temperature β‐relaxation is expected to be due to local motion of anhydroglucose rings, while the α‐relaxation is related to the side group motion. The data obtained are discussed in terms of the progressive destruction of the fibre structure, together with the increase of side group polarity due to cyanoethylation. © 1994 Society of Chemical Industry

Saad, G. R., A. A. Mansour, and A. H. Hamed, "Dielectric investigation of cold crystallization of poly(3-hydroxybutyrate)", Polymer, vol. 38, issue 16, pp. 4091 - 4096, 1997. AbstractWebsite

The dielectric behaviour of poly(3-hydroxybutyrate) (PHB) has been investigated for the glass (α) relaxation in the temperature and frequency ranges of -60 to 100deg;C and 103-105Hz, respectively. Also, the crystallization kinetics of PHB has been studied dielectrically as a function of heating rate, time and temperature. Crystallinity has a marked influence on the glass relaxation characteristics owing to the relative constraint imposed on the amorphous phase by the crystallites. Furthermore, the results obtained showed that: (1) the optimum crystallization temperature is about 25°C; (2) the time at which crystallization starts is a function of the working temperatures and apparently is reduced to just a few minutes at 40°C; and (3) the crystallization process is completed within a period of less than 1 h in the temperature range 20-40°C. The bulk crystallization phenomena could be also described by the Avrami equation with an exponent ∼ 3.8. © 1997 Elsevier Science Ltd.

Naoum, M. M., M. M. A. Moteleb, M. M. Shalaby, and G. R. Saad, "Dielectric investigation of isotropic and anisotropic solutions of cellulose acetate in dioxane", Polymer International, vol. 37, issue 1, pp. 27 - 32, 1995. AbstractWebsite

The dielectric and optical characteristics of a sample of cellulose acetate (DS = 2.45) in dioxane solutions were studied at 10–50°C of concentration 10–50 wt% to include both isotropic and anisotropic phases. The study showed that the loss maximum, εmax″, magnitude of polarization, (ε0 − ε∞), static dielectric constant, ε0, time of relation, (2πfm)−1, and refractive index, nD, steadily increase with concentration up to the critical concentration (41 wt%) and then decrease. The mean‐square dipole moment, 〈gμ2〉, decreases steadily up to the critical concentration then remains nearly constant, indicating that the isotropic solution changes to anisotropic, with smaller mean‐square dipole moment. Comparison between the results of cellulose acetate (CA) and those of hydroxypropyl cellulose (HPC) reveals that, at the critical concentration in dioxane, the cholesteric structure of HPC possesses a greater mean‐square dipole moment with higher temperature coefficient than does CA. The activation energy of the relaxation process for hydroxypropyl cellulose is higher, indicating a greater intrachain interaction compared with cellulose acetate. © 1995 Society of Chemical Industry

Moteleb, M. M. A., M. M. Naoum, M. M. Shalaby, and G. R. Saad, "Dielectric investigation of isotropic and anisotropic solutions of hydroxypropyl cellulose in dioxan", Polymer International, vol. 34, issue 4, pp. 363 - 367, 1994. AbstractWebsite

The dielectric behaviour of hydroxypropyl cellulose in dioxan has been studied at 10–50°C over a range of concentration of 10–55 wt% to include the isotropic and anisotropic phases. The study showed that the loss maximum ε″ max magnitude of polarization ε 0 − ε ∞ relaxation time 1/2πf m degree of broadening of the absorption curves 1–h or α, and the mean‐square dipole moment 〈gμ 2 〉, steadily increase with concentration up to 42 wt%, above which a rapid decrease takes place. This indicates that the isotropic solution transforms to an anisotropic solution with a smaller mean dipole moment. The critical concentration is realized to be temperature invariant. This was evidenced by measuring the refractive index of solutions covering the same concentration and temperature ranges. © 1994 Society of Chemical Industry

Naoum, M. M., G. R. Saad, M. M. Abdel-Moteleb, H. G. Shinouda, and H. A. Rizk, "Dielectric polarization and molecular interaction. Part I. Acetoacetanilide and benzoylacetanilide-triethylamine-benzene systems", Canadian Journal of Chemistry, vol. 65, issue 12, pp. 2760 - 2763, 1987. AbstractWebsite

The apparent molecular polarization at infinite dilution of acetoacetanilide, and benzoylacetanilide in five constant-ratio mixtures of triethylamine in benzene leads to the inference that the equilibrium constants of the association process between the anilide and the amine in benzene are 357 and 600, and that the dipole moments of the complexes formed are 4.43 and 5.25 D, respectively.

Saad, G. R., R. E. Morsi, S. Z. Mohammady, and M. Z. Elsabee, "Dielectric relaxation of monoesters based poly(styrene-co-maleic anhydride) copolymer", Journal of Polymer Research, vol. 15, issue 2, pp. 115 - 123, 2008. AbstractWebsite

A series of alkyl-grafted copolymers based on styrene-maleic anhydride (SMA) copolymers were synthesized by esterification of SMA with several long chain normal aliphatic alcohols. The prepared copolymers were characterized by FT-IR and 1H NMR and DSC. The dielectric behavior of these copolymers was investigated in the frequency 20-105 Hz and temperature -40 to 180 °C ranges. Two relaxation processes were observed, α, and β-relaxation. The former is associated with the glass-rubber transition and is characterized by the Vogel-Fulcher-Tammann temperature dependence and the latter relaxation is related to the local motion of the ester side groups attached to the polymer backbone. The apparent activation energy for the β-relaxation was found to depend significantly on the alkyl chain length. The dielectric analysis of the β-relaxation process detected is discussed. © 2007 Springer Science+Business Media B.V.

Saad, G. R., M. G. Botros, and R. I. Nessim, "Dielectric study of acetylated cotton cellulose and saponified cellulose acetate", Die Angewandte Makromolekulare Chemie, vol. 197, issue 1, pp. 23 - 39, 1992. AbstractWebsite

Dielectric relaxation data are reported at frequencies of 0.1 – 10000 kHz over a temperature range of 10–80°C on cellulose acetates of different degrees of substitution, and on saponified cellulose acetate. The acetyl substitution is found to remove the low‐frequency relaxation process, γ, previously observed in medicated cotton cellulose, and to affect the other higher‐frequency process, β, in different ways, depending on the acetyl content. Conversely, saponification of cellulose acetate leads to the reversion of these two processes but with different features. Analysis of the absorption bands is made, and an assessment of the results obtained is given. © 1992 Hüthig & Wepf Verlag, Basel

El-Shafee, E., and G. R. Saad, "A dielectric study of the photodegradation of poly(vinyl chloride) in air", Polymer Degradation and Stability, vol. 43, issue 3, pp. 315 - 318, 1994. AbstractWebsite

The dielectric absorption caused by dipolar relaxation of poly(vinyl chloride) photolytically degraded in air, using ultraviolet radiation, was studied on samples in the form of cast thin films. It was found that with the progress of photodegradation over a period of 10 h at 35 ± 2°C, the change in the magnitude of the dielectric parameters ε{lunate}m′', ε{lunate}0-ε{lunate}∞, ΔHε{lunate}0 and α can be practically represented as a three-staged process. © 1994.