Elastomers polybutadiene

The particle size of the dispersed phase depends upon the viscosity of the elastomer-monomer solution. Preferably the molecular weight of the polybutadiene elastomer should be around 2 x 10 and should have reasonable branching to reduce cold flow. Furthermore, the microstructure of the elastomer provides an important contribution toward the low-temperature impact behavior of the final product. It should also be emphasized that the use of EPDM rubber [136] or acrylate rubber [137] may provide improved weatherability. It has been observed that with an increase in agitator speed the mean diameter of the dispersed phase (D) decreases, which subsequently levels out at high shear [138-141]. However, reagglomeration may occur in the case of bulk... 

Graft polymerization of acrylonitrile and styrene on a preformed polybutadiene elastomer... 

Elastomers, synthetic -acrylic elastomers [ELASTOMERS, SYNTHETIC - ACRYLIC ELASTOMERS] (Vol 8) -butyl rubber [ELASTOMERS, SYNTHETIC - BUTYL RUBBER] (Vol 8) -chlorosulfonated polyethylene [ELASTOMERS, SYNTHETIC - CHLOROSULFONATED POLYETHYLENE] (Vol 8) -ethylene-acrylic elastomers [ELASTOMERS, SYNTHETIC - ETHYLENE-ACRYLIC ELASTOMERS] (Vol 8) -ethylene-propylene-diene rubber [ELASTOMERS,SYNTHETTC - ETHYLENE-PROPYLENE-DIENE RUBBER] (Vol 8) -fluorocarbon elastomers [ELASTOMERS, SYNTHETIC - FLUOROCARBON ELASTOMERS] (Vol 8) -nitrile rubber [ELASTOMERS, SYNTHETIC - NITRILE RUBBER] (Vol 8) -phosphazenes [ELASTOMERS, SYNTHETIC - PHOSPHAZENES] (Vol 8) -polybutadiene [ELASTOMERS, SYNTHETIC - POLYBUTADIENE] (Vol 8) -polychloroprene [ELASTOMERS, SYNTHETIC - POLYCHLOROPRENE] (Vol 8) -polyethers (ELASTOMERS, SYNTHETIC - POLYETHERS] (Vol 8) -polyisoprene [ELASTOMERSSYNTHETTC - POLYISOPRENE] (Vol 9) -survey [ELASTOMERS, SYNTHETIC - SURVEY] (Vol 8)... 

The carboxyl terminated polybutadiene (C-3000) is about equally effective to CTBN in heat distortion temperature and impact but considerably less effective in strength. From the haze data (the percent haze of ERL-4221 modified with 10 phr of CTBN and C-3000 were 17 and 85% respectively) it is quite clear that this elastomer (C-3000) is highly incompatible with the epoxy-hardener system in the cured state. A 2000 molecular weight polybutadiene elastomer, containing no carboxyl groups, was completely incompatible with the epoxy system and segregated in the cured state. 

Chemical Economics Handbook, CEH Accession No. 525.300 D, Product Review Polybutadiene Elastomers (1993 Update 1995). 

It is claimed that styrene/butadiene diblock polymers bring about an improvement in the hardness, strength, and processability of polybutadiene elastomers (27), as well as an improvement in the ozone resistance of neoprene rubber (28). Styrene diblock polymers have also been made with isoprene, a-methyIstyrene, methyl methacrylate, vinylpyridine, and a-olefins. Block copolymers of ethylene, propylene, and other a-olefins with each other have been made as well. Heteroatom block copolymers based on styrene or other hydrocarbons and alkylene oxides, phenylene oxides, lactones, amides, imides, sulfides, or slloxanes have been prepared. 

Some properties of sodium and zinc vulcanizates are compared with those of the acid precursor in Table 5.16. High tensile strength is a characteristic of ionic vulcanizates. As a comparison, a standard polybutadiene elastomer vulcanized with sulfur gives a strength of 1.9-5.8 MPa (275-841 Ibf/in. ), whereas an equivalent copolymer containing 1.5 mole% methacrylic acid, and vulcanized with... 

Three urethane-crosslinked polybutadiene elastomers (TB-1, TB-2, and TB-3) of varying crosslinking levels, along with a similarly crosslinked styrene-butadiene copolymer (HTSBR) and two polybutadiene polymers randomly crosslinked with dicumyl peroxide (PB-1 and PB-2), have been investigated to determine their viscoelastic behavior. Elsewhere, TB-1, TB-2, and TB-3 have been designated as HTPB-1, HTPB-2, and HTPB-3, respectively. 

Torsional creep measurements were made on the urethane-crosslinked polybutadiene elastomers at temperatures between —68 C and 25 C. The average molecular weight of a networks chain. Me, is 3400, 5200, and 8300 for TB-1, TB-2, and TB-3, respectively. The reduced shear creep compliance Jpit/ax) curves obtained for the three samples are shown in Figure 5.13. The reference temperatures are chosen to be 7.4°C, 0.0 C, and 17.0°C for TB-1, TB-2, and TB-3, respectively, so that superposition is achieved at shorter times... 

FIGURE 5.13 The logarithm of the reduced shear creep compliance curves, Jp t) (in Pa ), for the three urethane-end Unked polybutadiene elastomers displayed as a function of the logarithm of the reduced time t/ap (in seconds). The reference temperatures of reduction are chosen so that superposition is achieved at short times in the primary softening dispersion, (o) TB-1, 74 C, ( ) TB-2, 0°C, (e) TB-3, 17°C. 

Maier, T. R., Jamieson, A. M., and Simha, R., Phase equilibria in SBR/polybutadiene elastomer blends application of Flory-Huggins theory, J. Appl. Polym. Sci., 51 (6), 1053-1062 (1994). 

The control of chain structure and molecular weight afforded by the organolithium polymerization of dienes, has, of course, been of great technological interest [161,162,209]. Such product developments have been mainly in the form of (1) polybutadiene elastomers of various chain structures [162, 198,209] and functional end groups [210], (2) liquid polybutadienes [211], (3) butadiene-styrene copolymers (solution SBR) [69, 161, 162, 209], and (4) styrene-diene triblock copolymers (thermoplastic elastomers) [212]. 

Torsional creep measurements were made on the urethane-crosslinked polybutadiene elastomers at temperatures between -68 and 25°C.The average molecular weight of a networks chain. Me, is 3400, 5200, and 8300 for TB-1, TB-2, and TB-3 respectively. The reduced shear creep compliance Jp(t/ar) curves obtained for the three samples are shown in Fig. 18. The reference temperatures are chosen to be 7.4,0.0, and 17.0°C for TB-1, TB-2, and TB-3 respectively so that superposition is achieved at shorter times in the primary softening dispersion. The most loosely urethane-crosslinked TB-3 has the largest 7e = 2.5 x lO Pa There is a plateau intermediate between the glassy compliance 7g (not reached in these measurements) and /e, and its level is about 2.0 X 10 Pa in all three samples. The network chain density does not affect the form of the time-dependent response up to and including the intermediate plateau in the Jp(t) curves. Only the terminal dispersion, i.e., the approach to /e, is influenced. The shift factors, Uj, that were used to obtain the... 

FIGURE 19 The logarithm of the reduced retardation spectrum, Lp, shown as function of the logarithm of the reduced retardation time, 2/at, for the three urethane-end linked polybutadiene elastomers. (O) TB-1, ( ) TB-2, (0) TB-3. The response has been reduced to corresponding state temperatures of 74°C, 0°C, and 17°C, respectively for the primary softening transition. 

The logarithm of the reduced shear creep compliance Jp t/aj) of several elastomers are compared at 0°C in Rg. 20 as a function of the logarithm reduced time-scale log(i/flr)- The elastomers include (1) the urethane-crosslinked polybutadiene elastomer, TB-2, described in Subsection B (2)... 

J. G. Lacson, Polybutadiene Elastomers, Chemical Economics Handbook, SRI International, Menlo Park, Calif., Apr. 2000. 

---