Stress–strain optical study of styrene–butadiene and ethylene–propylene rubbery copolymers

1973 ◽  
Vol 17 (3) ◽  
pp. 709-719 ◽  
Author(s):  
J. Durisin ◽  
H. Leverne Williams
Keyword(s):  
Optical Study ◽  
Stress Strain ◽  
Ethylene Propylene ◽  
Styrene Butadiene

Polyisocyanates as Curing Adjuvants for Ethylene—Propylene Terpolymers

1964 ◽  
Vol 37 (4) ◽  
pp. 927-933
Author(s):  
J. R. Wolfee ◽  
J. R. Albin
Keyword(s):  
Tensile Strength ◽  
Low Cost ◽  
New Method ◽  
Mineral Filler ◽  
High Modulus ◽  
Stress Strain ◽  
Ethylene Propylene ◽  
Reinforcing Fillers ◽  
Light Color ◽  
Mineral Fillers

Abstract Ethylene—propylene—nonconjugated diene terpolymers yield vulcanizates of high modulus and tensile strength in the presence of strongly reinforcing fillers. In many applications where low cost, light color, or nonconductivity are required, it is necessary to use poorly reinforcing mineral fillers. The combination of poorly reinforcing mineral filler and amorphous EP terpolymer yields vulcanizates which do not have the excellent stress-strain properties characteristic of many black loaded stocks. The purpose of this paper is to present a new method of obtaining superior properties in mineral filled EP terpolymer vulcanizates.

Effect of Temperature on Stress-Optical Properties of Styrene Butadiene Block Copolymers

1967 ◽  
Vol 40 (5) ◽  
pp. 1373-1380 ◽  
Author(s):  
E. Fischer ◽  
J. F. Henderson
Keyword(s):  
Optical Properties ◽  
Block Copolymers ◽  
Network Structure ◽  
Effect Of Temperature ◽  
Stress Strain ◽  
Two Phase ◽  
Phase Systems ◽  
Effective Network ◽  
Restricted Mobility ◽  
Styrene Butadiene

Abstract Stress, strain, and optical properties of three elastomeric styrene butadiene block copolymers containing 31, 40 and 49 wt per cent styrene were studied as a function of temperature. Mechanical and optical properties indicate that these materials are two phase systems in which the polybutadiene chains form an elastomeric phase and the polystyrene a glassy phase with the latter providing physical crosslinks. Birefringence measurements indicate that decreases in modulus and strength of these materials are associated with decrease in concentration of elastically effective network chains. Independence of stress-optical coefficient of temperature suggests that the decrease in concentration of elastically effective chains is not due to onset of rubberlike behavior or flow within the polystyrene regions themselves, at least for temperatures below about 70° C. Rather, the decrease seems to be associated with increased mobility of the polybutadiene chains at higher temperatures, which also leads to an increase in the rate of stress relaxation. Birefringence measured during extension and retraction showed that stress strain hysteresis is due to restricted mobility of polybutadiene chain segments rather than to permanent viscous flow or to change in the effective network structure of the block copolymers. The ultimate properties of these rubbers were well correlated with the effective network structure in undeformed specimens.

Effect of Finite Extensibility on the Viscoelastic Properties of a Styrene-Butadiene Rubber Vulcanizate in Simple Tensile Deformations up to Rupture

1970 ◽  
Vol 43 (4) ◽  
pp. 714-734
Author(s):  
T. L. Smith ◽  
R. A. Dickie
Keyword(s):  
Strain Rate ◽  
Constant Strain Rate ◽  
Shift Factor ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Stress Strain ◽  
Temperature Function ◽  
Extension Ratio ◽  
Styrene Butadiene ◽  
Maximum Extensibility

Abstract Stress-strain and rupture data were determined on an unfilled styrene-butadiene vulcanizate at temperatures from −45 to 35° C and at extension rates from 0.0096 to 9.6 min−1. The data were represented by four functions: (1) the well-known temperature function (shift factor) aT; (2) the constant-strain-rate modulus, F (t, T) reduced to temperature T0 and time t/aT, i.e., T0F (t/aT)/T (3) the time-dependent maximum extensibility λm (t/aT); and (4) a function Ω(χ) where χ=(λ−1)λm0/λm, in which λ is the extension ratio and λm0 is the maximum extensibility under equilibrium conditions. The constant-strain-rate modulus characterizes the stress-time response to a constant extension rate at small strains, within the range of linear response; λm is a material parameter needed to represent the response at large λ; and Ω(χ) represents the stress-strain curve of the material in a reference state of unit modulus and λm=λm0. The shift factor aT was found to be sensibly independent of extension. At all values of t/aT for which the maximum extensibility is time-independent, the relaxation rate was also found to be independent of λ. These observations indicate that the monomeric friction coefficient is strain-independent over the ranges of T and λ covered in the present study. It was found that λm0=8.6 and that the largest extension ratio at break (λb)max is 7.3. Thus, rupture always occurs before the network is fully extended.

A novel chemical technique for compatibility of ethylene-propylene-diene monomer rubber and styrene-butadiene rubber in their blends

2016 ◽  
Vol 49 (4) ◽  
pp. 298-314 ◽  
Author(s):  
Sara Estagy ◽  
Saeed Ostad Movahed ◽  
Soheil Yazdanbakhsh ◽  
Majid Karim Nezhad
Keyword(s):  
Mechanical Properties ◽  
Heat Flow ◽  
Classical Problem ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Ethylene Propylene Diene Monomer ◽  
Scanning Calorimetry ◽  
Covalent Bonds ◽  
Ethylene Propylene ◽  
Styrene Butadiene

The market for commercial polymer blends has grown steadily. A good blend should have strong interphases between different parts of the constituted polymers. Lack of strong interphases is a classical problem of the blend industry. Ethylene-propylene-diene monomer rubber (EPDM)/styrene-butadiene rubber (SBR) blends have a very good aging resistance and good compression sets. However, these rubbers are partially miscible. To improve the miscibility of EPDM and SBR in their blends, a Lewis acid, AlCl3, was used to form EPDM–g–SBR copolymer through Friedel–Crafts reactions. The existence of covalent bonds between EPDM and SBR macromolecules was studied by the cure traces of the blends, that is, ΔTorque, Fourier transform infrared spectrums, differential scanning calorimetry (DSC) heat flow curves, thermogravimetric analysis curves, and scanning electron (SEM) micrographs. Subsequently, several blends with EPDM/SBR ratio of 40/60 and with various AlCl3 amounts were prepared and after curing, their mechanical properties were measured and compared. The results showed covalent bonds formed between SBR–EPDM and SBR–SBR macromolecules. An exothermic change in heat flow in the DSC curve was observed around 111.28°C, which can be attributed to the formation of carbocations in Friedel–Crafts reactions. Adding 2 phr AlCl3 had an efficient effect on EPDM–SBR and or SBR–SBR linkages. The mechanical properties of the cured blends, that is, tensile strength were lower when compared with corresponding values for prepared compound with SBR. Excellent compatibility between the two polymers and strong interphases were observed in SEM micrograph of the cured blend with 1 phr AlCl3.

Sign in / Sign up

Export Citation Format

Share Document