ABSTRACT:The free-radical polymerization behavior of 1-vinyl,2-pyrrolidone (NVP) was studied at low conversions, using capillary dilatometry. The aqueous media were kept at neutral pH and the studies were conducted isothermally, at 40 or 45°C. The azo-type initiators used were 4,4Ј-azobis-4-cyanopentanoic acid (ACPA), 2,2Ј-azobisisobutyronitrile (AZBN), and 2,2Ј-azobis[2-(2-imidazolin-2-yl)propane dihydrochloride] (ABDH). The monomer concentration and initiator concentration ranges were 1.17-2.34 mol L Ϫ1 and 1-8 mmol L
Ϫ1, respectively. The rates of polymerization (R p ) and orders of reaction with respect to NVP and the initiator were evaluated and the kinetic equations were found to be R p ϰ
The free-radical polymerization behavior of 1-vinyl,2-pyrrolidone (NVP) was studied at low conversions, using capillary dilatometry. The aqueous media were kept at neutral pH and the studies were conducted isothermally, at 40 or 45°C. The azo-type initiators used were 4,4Ј-azobis-4-cyanopentanoic acid (ACPA), 2,2Ј-azobisisobutyronitrile (AZBN), and 2,2Ј-azobis[2-(2-imidazolin-2-yl)propane dihydrochloride] (ABDH). The monomer concentration and initiator concentration ranges were 1.17-2.34 mol L Ϫ1 and 1-8 mmol L Ϫ1 , respectively. The rates of polymerization (R p ) and orders of reaction with respect to NVP and the initiator were evaluated and the kinetic equations were found to be R p ϰ [NVP] [ACPA] 1.2 ; R p ϰ [NVP] [AZBN] 1.1 ; and R p ϰ [NVP] 2.2 [ABDH] 1.1 . The polymers obtained were characterized by their viscosity numbers and correlation of the viscosity average molecular weights made with the type and amount of the azo initiator.
Studies of the dilute solution capillary viscosity and moisture sorption of commercial samples of epoxidized natural rubber (ENR 50) were carried out. Dilute solution viscometry of ENR 50 solutions was conducted in xylene, tetrahydrofuran, and methyl ethyl ketone solvents and the degradation due to shearing and oxidation for this rubber was followed. At average elevated temperatures and high relative humidities, epoxidized natural rubber ENR 50 shows high moisture sorption. Moisture sorption measurements at 100% RH and 34°C followed by desorption show near equilibrium moisture intake of 3.402-3.661 g H 2 O/100 g rubber, which agrees reasonably well with the estimated value of 4.108 g H 2 O/100 g ENR 50.
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