Thermal graft copolymerization of 4‐vinyl pyridine onto ethyl cellulose in homogeneous media. 1. Influence of ammonium persulfate

Abdel-Razik, E.A.

doi:10.1002/actp.1994.010450110

Cited by 13 publications

(11 citation statements)

References 14 publications

(1 reference statement)

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“…The results indicate that WC % and GP % decrease with increasing PVA content, whereas GE % increases. Therefore the increase in PVA content is always accompanied by an increase in solution viscosity ie the motion of macromolecule is restricted, so decreasing the WC % and GP % grafting parameters 23…”

Section: Resultssupporting

confidence: 83%

Reaction kinetics of graft copolymerization and thermochemical studies of the degradation of poly(vinyl alcohol) graft copolymer

Aggour

2001

Polymer International

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Poly(vinyl alcohol) (PVA) is a water‐soluble and biomedical polymer. 2‐Acrylamido‐2‐methyl‐1‐propanesulfonic acid was grafted onto PVA using ammonium persulfate as radical initiator. The influences of synthesis conditions such as temperature, concentrations of initiator, PVA and monomer were investigated. Both the initial rate of grafting and the final percentage of grafting were increased by an increase in reaction temperature. The reaction kinetics were studied to determine the rate constants of the first‐order reactions. An activation energy of 16.3 kJ mol−1 was found for the grafting reaction. The graft copolymers were characterized by IR and intrinsic viscosity measurements. A proposed mechanism of the grafting reaction is discussed. Kinetics of the thermal degradation were studied using a thermogravimetric method and the order of thermal stabilities are given. The apparent activation thermodynamic parameters, Ea, ΔH*, ΔS* and ΔG* were determined and correlated to the thermal stabilities of the homo‐ and grafted polymers. © 2001 Society of Chemical Industry

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Section: Resultssupporting

confidence: 83%

Reaction kinetics of graft copolymerization and thermochemical studies of the degradation of poly(vinyl alcohol) graft copolymer

Aggour

2001

Polymer International

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“…In Egypt, women have access to family planning as part of public primary health care (Rabie et al 2013; Ali 2002), and women’s use of long-acting reversible contraceptive methods increased steadily between 1984 and 2000 (Giusti and Vignoli 2006; Ali 2002). However, in the midst of rising fertility, the Ministry of Health and Population has observed a shift from IUDs to oral contraceptive pills in clinics (Abdel-Razik 2012). There remains a need to further understand factors that may contribute to this shift in method choice.…”

Section: Introductionmentioning

confidence: 99%

“…There remains a need to further understand factors that may contribute to this shift in method choice. Barriers to contraceptive use in Egypt include an absence of female physicians, a lack of physician training, son preference, region of residence, concerns about side effects, and husband’s disapproval (Giusti and Vignoli 2006; Ali 2002; Abdel-Razik 2012).…”

Section: Introductionmentioning

confidence: 99%

Women’s empowerment and short- and long-acting contraceptive method use in Egypt

Samari

2017

Culture, Health & Sexuality

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Egypt is ranked one of the most gender unequal countries, and fertility is at a two-decade high of 3.5 births per woman. Women's empowerment is a strategy used to promote contraceptive use and lower fertility, yet evidence from the Middle East is limited. This study uses 2005, 2008 and 2014 Egyptian Demographic and Health Survey data to examine recent patterns of contraceptive method choice and how women's empowerment is associated with contraceptive method type: none, short-acting or long-acting reversible contraceptive (LARC) methods. Using a nationally representative sample of 47,545 married women in their childbearing years, multinomial logistic regression models examine women's agency, specifically household decision-making and attitudes towards intimate partner violence and contraceptive method type. In 2014, LARC use significantly declined and short-acting method use was higher than in 2008. Women who made household decisions and were less accepting of intimate partner violence were more likely to use LARC (vs. no method). Women who made more joint decisions with spouses were more likely to use LARC (vs. no method) compared to those making individual decisions. Findings have implications for family planning programmes, and efforts involving men to increase household gender equality and lower the acceptance of intimate partner violence may promote LARC use in Egypt.

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“…19 -21 Therefore, grafting of cellulose in such homogeneous systems possesses no complexities. [22][23][24] During the past few years, work on homogeneous grafting of vinyl monomers onto cellulose and some cellulose derivatives dissolved in nondegrading solvent systems such as DMSO/PF 24 -27 and DMSO/ PhMe 28,29 have been tried using different initiators [e.g., ammonium persulfate (APS), potassium persulfate (KPS), azobisisobutyronitrile (AIBN), and benzoyl peroxide (BPO)] but so far, work on homogeneous graft copolymerization of high ␣-cellulose dissolved in a DMAc/LiCl solvent system has not been investigated. It is reported that cellulose can be dissolved in a high concentration up to 16% in solvent systems such as DMAc/LiCl and N-methyl-2,2-pyrolidine/ lithium chloride (NMP/LiCl) without degradation of the polymer chain.…”

Section: Introductionmentioning

confidence: 99%

Homogeneous graft copolymerization of acrylonitrile onto high α‐cellulose in a dimethyl acetamide and lithium chloride solvent system

Das

Saikia

2003

J of Applied Polymer Sci

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Homogeneous graft copolymerization of acrylonitrile (AN) monomer onto high ␣-cellulose was investigated in a lithium chloride/N,N-dimethyl acetamide (DMAc/LiCl) solvent system. Benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as radical initiators. By varying temperature, time, and monomer concentrations in grafting reactions, the optimum conditions for both initiator systems were fixed. The graft yield for the AN-BPO system was higher than that for the AN-AIBN system. The optimum conditions of reactions were at temperatures of 70 and 60°C with initiator concentrations of 0.4% (0.36 mmol) and 2% (1.24 mmol) for the AN-AIBN and AN-BPO systems, respectively, at a monomer concentration of 5% (14.1 mmol) solution. The number of grafts per cellulose chain was in the range from 2.2 to 1.1 for AN-BPO and 0.5 to 2.1 for the AN-AIBN system.

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Thermal graft copolymerization of 4‐vinyl pyridine onto ethyl cellulose in homogeneous media. 1. Influence of ammonium persulfate

Cited by 13 publications

References 14 publications

Reaction kinetics of graft copolymerization and thermochemical studies of the degradation of poly(vinyl alcohol) graft copolymer

Reaction kinetics of graft copolymerization and thermochemical studies of the degradation of poly(vinyl alcohol) graft copolymer

Women’s empowerment and short- and long-acting contraceptive method use in Egypt

Homogeneous graft copolymerization of acrylonitrile onto high α‐cellulose in a dimethyl acetamide and lithium chloride solvent system

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