Polyblends. I. Mechanical properties of polyblends of butadiene–acrylonitrile elastomers and copolymers of vinyl stearate and vinyl chloride

Abstract

SynopsisSeveral nitrile rubber elastomers were polyblended, across the composition range, with selected polymeric compositions containing vinyl chloride. The compositions incorporated were (a) bulk poly(viny1 chloride) (PVC); (b) copolymers of vinyl stearate and vinyl chloride containing, respectively, 0.21, 0.36, and 0.47 weight fraction of the vinyl ester; and (c) mixtures containing the same weight fractions of di-2-ethylhexyl phthalate (DOP) with PVC. Mechanical, viscoelastic, optical, and volatility properties were studied on all blends in this first paper. To accurately compare the mechanical properties of polyblends of different systems, a criterion of mechanical equivalence was taken as the observance of similar stresses at break for compositions selected to have identical 100% moduli. Optimum mechanical equivalence, therefore, occurred at the largest ratios of 100% modulus to break stress for all systems compared. Optimum mechanical property equivalence was observed for NBR blends with PVC and for similar blends of both internally and externally plasticized systems containing 0.21 weight fraction of plasticizer. However, considerably more nitrile rubber was needed for PVC blends to acquire the properties of the plasticized systems. Mechanical equivalence was observed, hut was not optimum for systems having more plasticizer because tensile strengths were lower. Polyblending with NBR improved the toughness and low-temperature properties of starting vinyl stearate copolymers. Improved toughness was indicated by the expansion of areas under stress-strain curves. Refractive index matching appeared to explain the transparency of the best films and their relative freedom from haze. On heating a t 85"C, poly(viny1 chloride) and the copolymer polyblends suffered no volatility loss. Volatility of DOP from the blends was 1.5 times greater than for PVC-DOP mixtures. Because modulus-temperature curves and mechanical Tg values of the filler component shifted with composition, the mechanical behavior of these blends was in harmony with an accepted standard of interdomain compatibility,

Variability in Surface Infrared Reflectance of Thirteen Nitrile Rubber Gloves at Key Wavelengths for Analysis of Captan

“…Controlled temperature environments were established using a Blue M Stabil-Therm Incubator (Blue M, Williamsport, PA) for temperatures 23. 5 Temperature and RH test conditions were measured using a Control Company Thermo-Hygro Recorder (Fisher Scientific, Tustin, CA), calibrated for temperature against a National Institute for Standards and Technology standard thermometer. The RH was verified with saturated salt solutions.…”

“…2 For polymer materials with refractive indexes between 1.5 and 1.6 the d p is about 0.65 to 0.7 lm at 1735 cm À1 . 5 The sampling depth is therefore about 1.9 to 2.1 lm for a glove material.…”

Behavior of copolymers, blends and alloys

“…In fact, this blend is still used today. Recent studies by Jordan et al (34) describe the mechanical and viscoelastic behavior of such blends (along with the behavior of vinyl chloride/vinyl stearate copolymers). Landi (35) has investigated the use of liquid NBRs, and Deanin et al (36) have noted that NBR can be added to plasticized PVC without sacrifice in abrasion resistance.…”

Polyblends. III. Correlation of the viscoelastic data for polyblends of NBR and plasticized vinyl chloride compositions with theories of polycomposite behavior

“…For a dispersion of hard spheres in a liquid or rubber-like matrix, Moo- (1) where k, is the Einstein coefficient with the value of 2.5 for dispersed spheres, u2 is the volume fraction of filler, and urn is a sedimenting volume defined as the critical maximum volumetric packing fraction above which the available liquid is no longer able to wet the filler properly because of its tight packing. This condition heralds phase inversion.…”