Cure characteristics of ethylene propylene diene rubber-polypropylene blends. I. Calculation of state of cure in blends containing conventional sulfur curing system under variable time-temperature conditions

Abstract

Various blends of polypropylene and ethylene propylene diene terpolymer were prepared. In these blends, rubber phases were compounded with an optimum sulfur curing system. The equivalent cure time and state of cure of the mixes were studied in the temperature range from 120 to 190°C by a rheometer. The temperature‐independent parameters (E1, E2, S1, and S2) and specification of the temperature dependence curing rate constant (k) and induction period (t0) were determined. The activation energies of the crosslinking reaction are almost similar for the virgin EPDM and EPDM/PP mixes. The value 9 Kcal/mol was considered sufficiently accurate for these mixes. A discussion of temperature‐conversion factor of the mixes is also provided. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1231–1236, 1997

Ternary elastomer nanocomposites based on NR/BR/SBR: Effect of nanoclay composition

“…On the other hand, the higher crosslink density of the compounds containing clay particles will consequently lead to higher torque values 22. In fact, M H – M L is a measure of the shear dynamic modulus, which indirectly relates to the crosslink density of the nanocomposites 23. It can be observed in Figure 1 that with increasing the nanoclay content, torque values rise.…”

Polypropylene/Ethylene–Propylene–Diene Terpolymer Blends

“…Cure characteristics of EPDM/PP blends were investigated by Sengupta and Konar (27). They calculated the state of cure in blends containing conventional sulfur curing system under variable time-temperature conditions.…”

Rheometers in scanning mode for cure of rubbers with low enthalpy: effect of heating rate and rubber–die contact

“…Nomenclature b heating rate, K min 21 C heat capacity of rubber in equation (8) Dt increment of time for calculation Dx increments of space for calculation E activation energy of cure reaction n order of overall cure reaction l thermal conductivity of rubber k 0 pre-exponential factor for rate of cure reaction in equation (5) M dimensionless number expressed by equation (9) Q heat generated by cure reaction in equation (8) r density of rubber S function defined by equation (12) used for calculating state of cure of rubber T temperature (K) TN n new temperature after elapse of time Dt at position n x longitudinal abscissa through thickness of rubber Z value of torque as a fraction of its maximum value in equation (3) resins, the samples should be heated up to a temperature at which the irreversible reaction starts, the fresh plastic uncured material leading to an elastic three-dimensional molecular network. Thus, the process of curing rubbers is rather complex, consisting of two stages, one with heat transfer by conduction through the sample thickness, the other with the slightly exothermic cure reaction.…”

“…3 per 10 K was also found for the sulphur vulcanisation of ethylenepropylene diene monomer (EPDM) blends around the reference temperature of 150uC. 8 Numerical models taking into account all the known facts, especially heat conduction through the sample and the kinetics of the heat generated by the cure reaction have been built and tested, either for the cure of NR with sulphur 4,9,10 or EPDM with peroxide. 11 These models are able to evaluate not only the profiles of temperature developed through the sample but also the profiles of state of cure, provided that the kinetics of the cure reaction are known.…”

“…From the fractional modulus-time values obtained, the activation energy and the pre-exponential factor have been calculated with the MDR for EPDM compounds. 8,[18][19][20] Very often, the modulus change with time follows first order kinetics and the rate constant varies with temperature according to an Arrhenius' equation. [18][19][20] The heat generated by the cure reaction is not considered, which is not a great drawback when the cure enthalpy is low.…”