Dynamic Mechanical Thermal Analysis and Transmission Electron Microscopy of Elastomer Blends

Abstract

Dynamic mechanical thermal analysis and transmission electron microscopy have been used to elucidate the structure of binary and ternary blends of NR, BIIR, and IM. Dynamic measurements at 10 Hz were able to resolve loss-tangent peaks into a major peak due to NR and a broad shoulder associated with BIIR and IM. Interpretation of these data in conjunction with electron micrographs indicate that the butyl polymers (BIIR and IM) form a second phase in a matrix of NR for compositions containing at least 67% NR. Dynamic mechanical properties and TEM micrographs of binary blends of NR with BIIR or IM show that the structure of these binary blends differ; IM forms larger, more distinct domains in the NR matrix. This difference in structure may result from the different molecular weights of the butyl polymers and the ability of BIIR to crosslink with NR. TEM micrographs of both binary blends indicate that carbon black is dispersed in the matrix material and is excluded from the isobutylene-rich domains, The two-phase structure of these blends and the partitioning of carbon black between the phases may enhance the fatigue lives of these composites. Cure temperatures in the range from 130°C to 170°C affected the properties and structure of only one blend studied in this work. This blend, an 80:20:20 mixture of NR, BIIR, and IM, respectively, was able to alter its morphology when the cure temperature was elevated. Material cured at 130°C contained domains with a wide variety of shapes and sizes; material cured at 170°C contained uniform, well-defined inclusions. This ternary blend was the only material that also exhibited a higher fatigue life when the cure temperature was raised. Achieving a well-defined dispersion in a two-phase elastomer blend apparently maximizes the fatigue life of the composite material.

Effect of rubber ratio, carbon black level, and accelerator level on natural rubber/bromobutyl rubber blend properties

“…An example of a calculation is shown as follows: for −1 on the coded scale, Table II gives the full experimental design and real value for each point. The design provides for eight factorial compounds (mix numbers 1–8), which enable modeling of linear and second‐order interactive effects; seven star points,9–14 which allow for modeling of quadratic curvature; and replication of the center point six times,15–20 which provides an assessment of error and model adequacy. Through the use of multivariable linear regression analysis, the data are fitted to a second‐order response surface equation of the general form in which Y is a response or dependent variable to be fitted, X i and X j are independent variables, b 0 is the constant term, b i is the linear coefficient, b ii is the quadratic coefficient, b ij is the interaction coefficient ( i ≠ j ), and k is the number of variables.…”

“…Its faster cure rate results in cure compatibility with other diene rubbers, thus enabling the development of useful blends. For example, BIIR has been blended with NR to produce a compound with higher damping and thermal stability 12–14. However, there is no report of any statistically designed experiments that have been carried out to determine the effects of varying specific factors on the cure characteristic and physical properties of this blend compound.…”

Phase separation structure in the polymer blend of fluorocarbon elastomer and hydrogenated nitrile rubber

“…In general, when immiscible polymers are mixed, multiple peaks will appear in the temperature tan δ chart, as long as the peak position of each constituent is not closely located 5. Because the tan δ chart (Figure 1) showed the single peak for each blend material, the constituent polymers were expected to be mutually compatible and to form a uniform phase.…”

Effect of the processing conditions and the addition of trans‐polyoctenylene rubber on the properties of natural rubber/styrene–butadiene rubber blends

“…The better the compatibilization, the closer the peaks related to the glass transition of the components. [14][15][16][17][18] When the rubbers components were blended, even upon the addition of TOR or with an increase in the mixing time, the temperatures at which the maxima of tan d occurred did not change, which indicated the strong immiscible character of the rubber forming the compounds.…”