Poly,butadienes viscosity

Most moisture-curing liquid adhesives utilize poly(oxypropylene) (PPG) polyols, as shown above. These raw materials produce among the lowest-viscosity prepolymers but may not have sufficient modulus at higher temperatures for some applications. A certain percentage of polyester polyols may also be utilized to boost performance, but these may cause a large increase in viscosity, and so they are more often used in conjunction with polyether polyols to provide a high-performance adhesive with workable viscosities. Poly(butadiene) polyols may be utilized for specific adhesion characteristics. 

The solution properties of dendrigraft polybutadienes are, as in the previous cases discussed, consistent with a hard sphere morphology. The intrinsic viscosity of arborescent-poly(butadienes) levels off for the G1 and G2 polymers. Additionally, the ratio of the radius of gyration in solution (Rg) to the hydrodynamic radius (Rb) of the molecules decreases from RJRb = 1.4 to 0.8 from G1 to G2. For linear polymer chains with a coiled conformation in solution, a ratio RJRb = 1.48-1.50 is expected. For rigid spheres, in comparison, a limiting value RJRb = 0.775 is predicted. 

Reaction of cw- 1,4-Poly butadiene and PVC. Et2AlClt-Cobalt Compound Catalyst. Commercial cw-1,4-polybutadiene prepared with a Et AlCl-cobalt compound catalyst system was freed of antioxidant by solution in benzene and precipitation with methanol. The cis-1,4,polybutadiene had an intrinsic viscosity in benzene at 25 °C of 2.4 and a greater than 96% cis-1,4 content. 

Fig. 3.6 shows the results of viscosity determination for a linear temperature increase in a polyurethane based on poly (butadiene diol), diphenylmethane diisocyanate, and diamine. 

Abbreviations y x AFM AIBN BuMA Ca DCP DMA DMS DSC EGDMA EMA EPDM FT-IR HDPE HTV IPN LDPE LLDPE MA MAA MDI MMA PA PAC PB PBT PBuMA PDMS PDMS-NH2 interfacial tension viscosity ratio atomic force microscopy 2,2 -azobis(isobutyronitrile) butyl methacrylate capillary number dicumyl peroxide dynamic mechanical analysis dynamic mechanical spectroscopy differential scanning calorimetry ethylene glycol dimethacrylate ethyl methacrylate ethylene-propylene-diene rubber Fourier transform-infra-red high density polyethylene high temperature vulcanization interpenetrating polymer network low density polyethylene linear low density polyethylene maleic anhydride methacrylic acid 4,4 -diphenylmethanediisocyanate methyl methacrylate poly( amide) poly( acrylate) poly(butadiene) poly(butylene terephtalate) poly(butyl methacrylate) poly(dimethylsiloxane) amino-terminated poly(dimethylsiloxane)... 

Impact-modified polystyrene is mainly produced by mass polymerization, either in tower cascades or tank/tower cascades. In the latter case, particle size and morphology can be defined by variation of the viscosity ratio between the continuous and the discontinuous phases, the stirrer velocity, the molecular weight of the poly butadiene rubber and the amount of rubber. Typical particles sizes are 2-20 xm, this being the optimum for effectively dissipating impact energy. 

Epoxy-Terminated Poly (butadiene-co-acrylonitrile) (ETBN). A mixture of 730 g of bisphenol A diglycidyl ether (5.4 mol epoxy/kg), 200 g of carboxy-terminated poly (butadiene-co-acrylontrile) (Hycar 1300 x 13 from BFGoodrich, 26 wt% acrylonitrile content, acid number of 32 mg KOH/g), 64 g of bisphenol A, and 5 g triphenylphosphin was heated at 130 °C for 3 h to yield ETBN with a viscosity of 130,000 mPa-s (40 °C) and 3.3 mol epoxy/kg. 

The superior cold properties of lithium polymers were even more pronounced in the case of butadiene-styrene copolymers than in the poly butadienes. As Figure 2 shows, a butadiene-styrene copolymer (33% styrene) prepared with lithium outperformed LTP (23.5% styrene, emulsion recipe, 5°C.) by 21 °C. in regard to the temperature at which Young s bending modulus reaches 10,000 pounds per square inch. The fact that the lithium polymer had a higher styrene content and also a higher Mooney viscosity (130 vs. 49) than LTP should have affected its cold properties adversely therefore, the superior performance of the lithium copolymer is significant. 

Figure 7-1. Dependence of the diffusion coefficients of m-l,4-poly(butadienes), BR, of molar masses A/br = 2900, 5500, 18,000, and 25,000 g/mol on the viscosity 171 of the solvent at 40° C. Benzene, pentachloropropane, and /raM5-l,4-poly(pentenamers) of molar masses between 2500 and 30 000 g/mol were used as solvents (after M. Hoffman).

Figure 7.9. Dependence of the melt viscosity rj of polymers on the parameter Zw (see text) at 021 0. For easier comparison, the 17 values of the different types of polymer have all been multiplied by a constant factor of C. PDMS, Poly(dimethyl siloxane) PIB, poly(isobutylene) PB, poly(butadiene) PMMA, poly(methyl methacrylate) PVAC, poly(vinyl acetate) PS, poly(styrene) (after T. G. Fox).

Low-molar-mass poly(butadiene) oils with 80%-97% cw-1,4 contents are produced with other Ziegler catalysts (for example, cobalt compounds with alkyl aluminum chlorides or nickel compounds with trialkyl aluminum and boron trifluoride-etherate). The products have few cross-links and dry as fast as wood oil and faster than linseed oil. Conversion of the poly (butadiene) oils with 20% maleic anhydride gives air-drying (air-hardening) alkyd resins. Modified poly (butadiene) oils stabilize erosion-endangered soils. Because of its low viscosity, the aqueous emulsion penetrates the surface soil layers. The surface crust is reinforced by an oxidative bonding process. Since no skin is formed on the soil crust, the aqueous absorption characteristics of the soil are retained. 

Suspension II was prepared by using a matrix of poly(butadiene acrylonitrile acrylic acid) terpolymer [PBAN] with 60% by volume of ammonium sulfate ground to an average particle size of 23 pm, exhibiting a standard deviation of 13 pm. The particles had low aspect ratios as observed with Scanning Electron Microscopy (SEM). The matrix in suspension II was also a Newtonian fluid with a viscosity of 37 Pa.s at 25 C. 

Zero-shear viscosity versus molecular weight for nearly monodisperse linear hydrogenated 1,4-poly butadienes at 190 °CThe lines showthe fits ofthedatatotheMilner-McLeish model... 

Figure 9.15 Zero-shear viscosity versus vol. fraction stars for bidisperse 1,4-poly butadiene star-linear blends as at 7= 25 "C.The symbols are for mixtures of a three-arm star of molecular weight 127,000 with linear polymers (M = 36,800) (M = 100,000) A(M = 68,000).The curves are the predictions of the theory of Milner etal. [23] using a = 4/3. The solid lines are for predictions with disentanglement relaxation and the dashed lines are without disentanglement relaxation.The data are from Struglinski etal. [35].The parameter values are the same as in Fig. 9.6. From Park and Larson [27].

Emulsion polymerization is the most important process for production of elastic polymers based on butadiene. Copolymers of butadiene with styrene and acrylonitrile have attained particular significance. Polymerized 2-chlorobutadiene is known as chloroprene rubber. Emulsion polymerization provides the advantage of running a low viscosity during the entire time of polymerization. Hence the temperature can easily be controlled. The polymerizate is formed as a latex similar to natural rubber latex. In this way the production of mixed lattices is relieved. The temperature of polymerization is usually 50°C. Low-temperature polymerization is carried out by the help of redox systems at a temperature of 5°C. This kind of polymerization leads to a higher amount of desired trans-1,4 structures instead of cis-1,4 structures. Chloroprene rubber from poly-2-chlorbutadiene is equally formed by emulsion polymerization. Chloroprene polymerizes considerably more rapidly than butadiene and isoprene. Especially in low-temperature polymerization emulsifiers must show good solubility and... 

When we compared the viscosities of solutions of natural rubber and of guttapercha and of other elastomers and later of polyethylene vs.(poly)cis-butadiene, with such bulk properties as moduli, densities, X-ray structures, and adhesiveness, we were greatly helped in understanding these behavioral differences by the studies of Wood (6) on the temperature and stress dependent, melting and freezing,hysteresis of natural rubber, and by the work of Treloar (7) and of Flory (8) on the elasticity and crystallinity of elastomers on stretching. Molecular symmetry and stiffness among closely similar chemical structures, as they affect the enthalpy, the entropy, and phase transitions (perhaps best expressed by AHm and by Clapeyron s... 

Figure 10. Shear viscosity as a function steady-state shear rate for poly(sty-rene-b-butadiene-b-styrene) at 150°C (after Ref. 47)...

Figure 11. Dynamic shear viscosity as a function of temperature for poly-(styrene-b-butadiene-b-styrene) at various angular frequencies (77)...

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