Prediction of the lifetime of nitrile-butadiene rubber by FT-IR.
A quantitative measurement method with FT-IR was proposed for a thermal degradation analysis of nitrile-butadiene rubber (NBR). An NBR film was prepared as a model sample on a barium fluoride (BaF2) crystal plate, which was subjected to a heat treatment. The absorbances of various functional groups were measured directly by FT-IR after thermal degradation at high temperatures. By measuring the absorbances, it was possible to readily determine quantitatively each of the functional groups after the degradation of NBR. By assuming that the NBR lifetime was the point at which the absorbance of a carbon-carbon double bond reaches 45% of that prior to thermal treatment, a method for predicting the lifetime of NBR heated below 150 degrees C was proposed, by using an Arrhenius plot of the heating time versus heating temperature.
Improved ionic conductivity of nitrile rubber/Li(CF3SO2)2N composites by adding imidazolium-type zwitterion
Abstract Polymer electrolytes based on the composite of nitrile rubber (NBR; poly(acrylonitrile-co-1,4-butadiene)) and Li(CF3SO2)2N (Li(Tf)2N) were prepared and their ionic conductivity was evaluated. NBR with nitrile content of 33% was mixed with 25 wt% Li(Tf)2N to show the highest ionic conductivity, while still in the rubbery state. Furthermore, addition of 9.2 wt% imidazolium-type zwitterion enhanced the ionic conductivity of about 8 times (5.6 × 10− 6 S cm− 1 at 50 °C) with lithium ion transference number of 0.32. FT-IR investigations suggested that the interaction between NBR and Li+ ion decreased by the addition of zwitterion. DSC measurements on the composites consisting of NBR, Li(Tf)2N, and zwitterion strongly suggested micro-phase separation between NBR-rich phase and zwitterion-rich phase.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.