Mooney viscosity elastomer

Molecular Structure. The chain stmcture is as shown in Table 1 and molecular weights of 300,000—500,000 are achieved. The Mooney viscosities are in the range of 40—70 leading to a soft elastomer, which requires carbon black reinforcement for higher modulus. 

The bulk viscosity control parameter for CSM, as with other elastomers, is molecular weight M and molecular-weight distribution (MWD). Mooney viscosity for CSM is determined by selection of the polyethylene precursor. 

Manufacturer Trade Type Grade name elastomer designation Oil content (phr) Mooney viscosity (T + 8 ) at 127 C Ethylene content Diene type Diene content Molecular weight distribution classification... 

In order to test this concept a series of compounds was prepared in a 5 L Shaw Intermix (rubber internal mixer, Mark IV, Kl) with EPDM (Keltan 720 ex-DSM elastomers an amorphous EPDM containing 4.5 wt% of dicyclopentadiene and having a Mooney viscosity ML(1 +4) 125°C of 64 MU 100 phr), N550 carbon black (50 phr), diisododecyl phthalate (10 phr), stearic acid (2 phr), and l,3-bis(tert-butylperoxy-isopropyl)benzene (Perkadox 14/40 MB ex Akzo Nobel 40% active material 6 or 10 phr). A polar co-agent (15 phr) was admixed to the masterbatch on an open mill and compounds were cured for 20 min at 180°C in a rheometer (MDR2000, Alpha Technologies). The maximum torque difference obtained in the rheometer experiments was used as a measure of... 

FIGURE 16.12 Mooney viscosity at 175°C of butadiene elastomer mill mixed with 50 phr of N-234 10 phr of naphthenic oil with the labeled loading of a commercial peptizer (diphenyl dibenzamido-disulfide). 

Grades of butyl differ by the level of unsaturation, molar masses characterized by Mooney viscosity ML 1 + 8 (100 or 125° C), and the characteristics of the eventually added stabilizer (staining or nonstaining). Butyl rubber, which ranks third in total synthetic elastomers consumed, has unique properties and applications, due to its low gas permeability, to its high hysteresis, and to its low level of unsaturation, sufficient for vulcanization but still providing excellent resistance to oxygen and ozone. 

Basic properties. The basic properties of ECH elastomers can also be found in detail in the above-mentioned reviews [108-110]. The homo-and copolymers have a high specific gravity (1.4-1.5). The Mooney viscosities are of the same range as for other commercial elastomers. Ozone, heat, fuel and oil resistance are good. An excellent resistance to vapor permeation by hydrocarbons, fluorocarbons, and air was observed. 

Elastomer Halogenating agent Halogen content (average value) Scattering by halogen compounds, mass % Mooney viscosity at 125 =C... 

It should be noted here that commercial high molecular weight isobutylene-based elastomers are characterized by the so-called Mooney viscosity, not by molecular weight or molecular-weight distribution. This standardized low shear viscosity measurement is used to grade all synthetic and natin-al elastomers and rubbers (212). Interestingly, this highly prevalent method in indnstiy is rarely ever mentioned in textbooks or encyclopedias. 

The successful epoxidation of NR, by employing a hydrogen peroxide/formic acid system under controlled conditions, has ensured epoxidized rubber (ENR) its place in the elastomer market. Essentially, ENR of any desired level of epoxidation ranging from 1 to 90% can be prepared. Increasing the level of epoxidation systematically changes the properties of the rubber. The increase in Jg and Mooney viscosity of ENR with increase in epoxidation level is indicated in Table 12.5. Currently ENR 10, 25, 50 and 60 (10, 25, 50 and 60% mole epoxidation, respectively) can be found on the market. Scheme 12.4 shows the structural formulae of ENR. 

Hydrogenated acrylonitrile-butadiene robber (HNBR)-Therban 3407, containing 34 % of acrylonitrile units and residual double bonds max 0.9 %, Mooney viscosity 70 was purchased from Lanxess. Dicumyl peroxide obtained from Aldrich was used as cross-linker. Co-agents consisted of nanostructured metal oxides magnesium, zinc or calcium oxide provided by Aldrich and unsaturated acids acrylic acid (Aldrich) or monoallyl maleate (synthesized by Department of Organic Chemistry- Technical University of Lodz). The composition of a typical elastomer blend was HNBR-100 phr, DCP- 3 phr, metal oxide- 3 phr, unsaturated acid-1 phr. 

In many cases of batch and semi-batch polymerization control there are no on-line measurements of polymer quality (for example, polymer composition, molecular weight) during the batch and these measures of end-use properties are only available at the end of the batch. In this case recipe modifications from one run to the next are common. The minimal information needed to carry out this type of mn-to-run control is a static model relating the manipulated variable to the quality variables at the end of the batch. As pointed out in Ref 7, this model can be as simple as a steady-state (constant) gain relationship or a nonlinear model that includes the effects of different initial conditions and the batch time. The philosophy of statistical process control can be very useful in this case, since the polymer quality variable (for example the Mooney viscosity in elastomer manufacture) can be plotted for each successive batch on a Shewhart (%-bar) chart with the upper and lower control limits placed at three standard deviations above and below the target. 

The Mooney viscosity is the torque generated on a spindle rotating at constant angular velocity, immersed in a polymeric material between heated dies. It is one of the most widely used industrial measures of bulk viscoelastic properties of polymeric materials, especially elastomers and rubbers. Oftentimes, the Mooney viscosity is of greater practical significance than the dynamic mechanical determination of G and G". The notion of Mooney viscosity is well grounded in the principles of continuum mechanics but involves the empirically determined Mooney viscosity and related parameters. 

There is no official standard classification for butyl rubber. These elastomers are classified usually by their Mooney viscosity (ASTM D1646), and the mole percent unsaturation (which is proportional to the amount of the second monomer (isoprene) is generally not greater than 3%. Higher mole percent unsaturation will increase the cure rate but can hurt the ozone resistance imparted to the cured rubber compound. 

There is no official classification system for epichlorohydrin. However, Mooney viscosity (ASTM D1646) is commonly used to crudely define average molecular weight. The molar content of ethylene oxide present in ECO is important. Greater ethylene oxide present will improve the elastomer s low-temperature properties. Originally it was found that a 50 50 molar ratio of epichlorohydrin and ethylene oxide gave one of the best compromises in properties, with good low-temperature properties and only a small loss in oil resistance. 

Materials. Ethylene-octene rubber (POE)- Engage 8150, copolymer of ethylene and 39 wt.% 1-octene, with a melt flow index (MFI) of 0.5 g/10 min (190 C, 2.16 kg) and Mooney viscosity 35, was purchased from Dow Chemical. As a cross-linker dicumyl peroxide (98%) obtained from Aldrich was used. Nanostructured metal oxides magnesium (50 nm particle size (BET)), zinc (<100 nm particle size (BET)), calcium oxide (160 nm particle size (BET)) and unsaturated acids itaconic (99%), crotonic (98%), sorbic (99%) acid were provided by Aldrich. Composition of typical elastomer blend POE-100 phr, DCP-1.5 phr, metal oxide-7 phr, unsaturated acid-2 phr. 

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