Poly,butadienes linear

Consider tor example, a melt of 1,4-poly butadiene linear chains with M—130000gmol The molar mass of a polybutadiene Kuhn monomer is Mo= I05gmol (see Table 2.1) so this chain has N = MjMo 1240 Kuhn monomers. At 25 °C, this polymer is 124 K above its glass transition and its oscillatory shear master curve is shown in Fig. 9.3. The time scale for monomer motion is tq = 0.3 ns, An entanglement strand of 1,4-polybutadiene has molar mass M — I900gmol (see Table 9.1) and therefore contains N — M jMQ= % Kuhn monomers. The whole chain has N/Ne = MjMs 68 entanglements. The Rouse time of the entanglement strand Te = 0.1 ps [Eq. (9,16)]. 

The Mn of the polymer increased linearly with increasing conversion and reached 1530 x 103 at 85% conversion when NdCl3-iPrOH/AlEt3 (1 10) was used in heptane at — 70 °C, but Mw/Mn (1.8-2.5) showed no change with conversion. The number N of polymer chains per metal atom was 1.09-1.43 at — 70 °C, and increased to 2.0-3.0 when the polymerization temperature was raised to 0 °C. Most noteworthy is a very high cis-content realized at — 70 °C, which amounted to 99.4%. This indicates the existence of the anti-ir-allyl-Nd species rather than the syn-7i-allyl-Nd species in the polymerization system. The ds-1,4-content of poly(butadiene) increased as the AlEt3 concentration was lowered [90]. 

AFM Atomic force microscopy aPP Atactic polypropylene DSC Differential scanning calorimetry HDPE High-density polyethylene iPP Isotactic polypropylene LLDPE Linear low-density polyethylene MD Microdomain ODT Order-disorder transition PB Poly(butadiene)... 

The polymer types shown are linear polystyrene, two types of branched polystyrene (methyl methacrylate), poly (vinyl chloride), poly butadiene poly (phenyl soiloxane), and two types of copolymer. 

The synthesis and characterization of a series of dendrigraft polymers based on polybutadiene segments was reported by Hempenius et al. [15], The synthesis begins with a linear-poly(butadiene) (PB) core obtained by the sec-butyllithium-initiated anionic polymerization of 1,3-butadiene in n-hexane, to give a microstructure containing approximately 6% 1,2-units (Scheme 3). The pendant vinyl moities are converted into electrophilic grafting sites by hydrosilylation with... 

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. 

Upon irradiation, 1,4 polybutadienes and poly(butadiene-styrene) form free radicals relatively readily, and their concentration has been found to increase linearly proportional to dose up to approximately 100 Mrad (1,000 kGy). ... 

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. 

The low catalyst activity in toluene and the found non-linear Mn-con-version characteristics are explained by chain-transfer reactions. A reaction scheme that accounts for the abstraction of a proton from toluene by the allyl-end of the growing poly(butadiene) chain is given in Scheme 13. 

Recently, the impact of the metal alkyls TIBA, DIBAH and ZnEt2 on molar mass was comparatively studied. In these studies ternary NdV-based catalyst systems were used [178-182]. The first two of these studies focus on molar mass control by DIBAH and by TIBA. Linear dependencies of Mn on monomer conversion were obtained. In addition, PDIs decreased with increasing monomer conversion. On the basis of these observations it was concluded that chain transfer of living poly(butadien)yl chains between Nd and Al is fully reversible. A reaction mechanism which accounts for these features is outlined in Scheme 32. 

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)... 

Sisman and Bopp, Charlesby, Turner and Petrov and Karpov studied the yield of total gas evolution from natural mbber, poly butadiene and various GR-S type copolymers subjected to ionizing radiation (reactor, Co or electron accelerator). Most of the gas is H2 + CH4 (100% in the case of polybutadiene), however for some rubbers a small amount of CO2 + C3H6 was found also. Turner found that under bombardment with accelerated electrons, the evolution of hydrogen from purified natural mbber was linear with dose, up to ISO megarads, and corresponded to G(H2) = 0.64. This radiolytic yield is noticeably smaller than those found in low-molecular-weight olefins. 

Yilmazer and Kalyon (Yilmazer and Kalyon, 1989, Kalyon and Yilmazer, 1990) described the rheology of highly filled suspensions (ammonium sulfate in poly(butadiene acrylonitrile acrylic acid)). They examined steady and dynamic rheology and found that wall slip and non-linear dynamic rheology are prevalent in these highly filled systems. 

A hindered amine light stabiliser has been found to enhance the light stability of blends of low and linear low density polyethylene with the latter contributing linearly to the overall stability of the blend. In coatings hindered piperidine light stabilisers are also effective especially when used in conjunction with a benzotriazole absorber while surface protection of styrene copolymers with 2-(2-hydroxy-5-vinylphenyl)benzotriazole requires a small amount of a hindered piperidine stabiliser. Polymeric hindered piperidine compounds on the other hand have been found to inhibit the singlet oxygen attack on poly(butadiene). ... 

The resulting polybutadiene is a polymer with 1,4 cis, 1,4 trans and 1,2 microstructures. The resulting polybutadiene diol is perfectly linear having a high proportion of 1,2 microstructure (Figure 9.3). The functionality is very close to the theoretical functionality f = 2 OH groups/mol (92-93% bifunctional poly butadiene) [16-24]. 

Figure 9-19. A universal gel-permeation chromatography calibration curve obtained from measurements on linear poly(styrene) (O), comb-branched poly(styrene) (O ), star-branched poly(styrene) ( ), poly(methyl methacrylate) ( ), poly(vinyl chloride) (a) c -l,4-poly-(butadiene) (A), poly(styrene)-poly(methyl methacrylate) block copolymer (Qj ), random copolymer from styrene and methyl methacrylate O), and ladder polymers of poly(phenyl siloxanes) ( ) (according to Z. Grubisic, P. Rempp, and H. Benoit).

Budene solution polybutadiene (solution polymerized) is cis-1,4-poly(butadiene) produced with stereospecific catalysts which yield a controlled MWD, which is essentially a linear polymer. Butadiene rubber, polybutadiene, is solution-polymerized to stereospecific polymer configurations " by the additional polymerization of butadiene monomer. The following cis- and trans-1,4-polybutadiene isomers can be produced cis-1,4-polybutadiene with good dynamic properties, low... 

Poly(butadiene-co-styrene), Buna-S linear fraction Toluene 30 21.4 0.74 3-20 A [148]... 

Figure 20 Chromatogram of poly(methyl methacrylate) 3, poly(styrene) 2 and poly(butadiene) 1. Chromatographic conditions 30-min. linear gradient, 100% methanol to 100% tetrahydrofuran at 1 mL/min. NovaPak Cyano-Propyl 3.9 x 75 mm, 4-pm column at 30°C, evaporative lightscattering detector.

The polymers are crystalline and have a linear head-to-tail 1,4 enchainment with a trans-di-isotactic structure the two lateral substituents of each base unit are in the erythro steric positions as revealed by IR and X-ray data, which are similar to those of trans-1,4-poly butadienes. From experiments carried out using labelled butyllithium as initiator,... 

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].

Many important advances have been made in the nomenclature of polymer blends, grafts, blocks and IPN s. These include a nomenclature document recently published by the lUPAC Nomenclature Committee and one now under consideration. Briefly, two advances were made that relate to IPN s. The first was the use of the prefix cross- to indicate a crosslinked polymer. Thus, cross-poly-butadiene is distinguished from the linear product, written polybutadiene. The second advance was the introduction of the symbol -inter-, which means interpenetrating. Thus, cross-poly-(ethyl acrylate)-mtcr-cross-polystyrene (1) represents the IPN based on poly(ethyl acrylate) and polystyrene. The symbol -inter- has exactly the equivalent meaning as -block- and -graft- possess for block and graft copolymers, respectively. 

Chlorosilanes were used applying an identical reaction procedure to prepare either quaterarm pol)miers of type ABCD or 4- miktoarm polymers of type A2B2. A, B, C, D correspond to PS, PBd, PI, and poly(4-methylst5n ene), respectively [33]. That method was extended recently to well-defined poly(iso-prene)/poly(butadiene) A2B2 copolymers [34]. The presence on the same nodu-lus of chains exhibiting different chemical structures leads to original solution properties. Roovers et al. [35] have examined in detail the solution properties and compared the specific behavior of these miktoarm star-shaped polymers to linear diblock copolymers. That strategy was extended to the preparation of... 

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