Polyethylene hydrogenated polybutadiene

S-B,.4 Polystyrene 1,4-Polybutadiene Poly(vinyl cyclohexane) Polyethylene Hydrogenation of both blocks... 

Linear Polyethylene with Randomly Distributed Ethyl Branches (Hydrogenated Polybutadiene)... 

FIG. 18.3 Activation energy of diffusion as a function of Tg for 21 different polymers from low to high temperatures, ( ) odd numbers (O) even numbers 1. Silicone rubber 2. Butadiene rubber 3. Hydropol (hydrogenated polybutadiene = amorphous polyethylene) 4. Styrene/butadiene rubber 5. Natural rubber 6. Butadiene/acrylonitrile rubber (80/20) 7. Butyl rubber 8. Ethylene/propylene rubber 9. Chloro-prene rubber (neoprene) 10. Poly(oxy methylene) 11. Butadiene/acrylonitrile rubber (60/40) 12. Polypropylene 13. Methyl rubber 14. Poly(viny[ acetate) 15. Nylon-11 16. Poly(ethyl methacrylate) 17. Polyethylene terephthalate) 18. Poly(vinyl chloride) 19. Polystyrene 20. Poly (bisphenol A carbonate) 21. Poly(2,6 dimethyl-p.phenylene oxide). 

Eor the typical commercial polypropylene copolymer systems the viscosity of the matrix phase is quite high, and the molecular diffusion and solubility of the minor phase component in the matrix phase are relatively high. These factors tend to favor the evaporation/condensation, that is, Ostwald ripening, mechanism and suppress the coalescence mechanism in these systems. Mirabella and coworkers studied a series of multiphase systems, including a hiPP (30), a high density polyethylene (HOPE)/ hydrogenated polybutadiene (HPB) blend, (31) and an unbranched PE molecular... 

Self-diffusion in the melt of polyethylene (PE) (or hydrogenated polybutadiene) has also been investigated rather extensively. Figure 8-4, taken from Tirrell s review [2], shows typical experimental data. Each set of data points is fitted closely by a straight line of slope -2, consistent with the reptation theory. However, we see again that the NMR data [17, 18, 22, 23] appear above those from tracer diffusion [24, 25] and neutron scattering [26]. The reason for the discrepancy was left unexplained in Tirrell s paper. 

Despite these observations, analysing the SEC Rl-elution volume traces with a linear polyethylene calibration curve appears to be valid, in that the short-chain branches did not substantially alter the molecular dimensions. In particular, hydrogenated polybutadienes with 2-5% ethyl branches, an excellent model system for n-butene-1 copolymer systems, elute at the same retention volume as HDPE with the same molecular mass, and they have been used widely as molecular mass standards for HDPE. Unfortunately, the effect... 

F. 107. Dissolution or melting temperature of 9% solution of gels and of dilute solution crystals vs mole percent branches hydrogenated polybutadiene gds ( ) ethy ene-vin acetate gds hydrogenateid polybutadiene solution crystals (O chlorinated polyethylene gds [340] ). Reproduced from Macromolecules [Ref. 338] by the courtesy of the authors and of The American Chemical Society... 

Adhesives recommended include epoxies, polyurethane, silicone, nylon-epoxy, nitrile-phenolic, neoprene-phenolic, acrylic, cyanoacrylate, anaerobics, and partially hydrogenated polybutadiene (for bonding copper to polyethylene). 

The standard measurement of the yield for an event resulting from the irradiation process is expressed as the G factor. This factor is universally accepted [16] and is defined as the event yield per 100 eV of energy deposited in the material. The SI unit for G is xmol For the purposes of this review events per 100 eV will be used throughout. The most commonly quoted G factors are for crosslinking, chain scission, and gas evolution, G(X), G(S), and G(Gas), respectively. There may be several different values for the G-factor in the literature since several different methods of measurement may be used to determine the event yield. If different methods or standards are used to determine molecular weights, they can lead to widely different G-factors. For example, in the case of a low density polyethylene values for G(X) of 0.9 or 1.7 are obtained using the hydrogenated polybutadiene or polystyrene calibrations, respectively [17]. 

Figure 7. Scanning electron micrographs of polyethylene copolymers, (a) Hydrogenated polybutadiene (ethylene-butene)...

Common SS include polyethers, polyesters and polyalkyl glycols with glass transition temperatures in the range of -70°to -30°C. Commonly used macrodiols in the PUs synthesis are polyalkyl-diols, such as polyisobutylene diol [70], polybutadiene (PBU) [20, 71], or oligo-butadiene diols [72] as well as hydrogenated polybutadiene diol [20] polyether diols polytetrahydrofuran (PTHF or PTMO) [50-52], polyethylene glycol (PEG) or (PEO) [73], polypropyleneoxide (PPO) [73] or mixed blocks of them PEO-PPO-PEO [74] and PPO-THF [54] polyester diols poly(ethylene adipate) (PEA) [4,20], poly(butylene adipate) (PBA) [20, 73], and latterly polycaprolactone diol (PCL or PCD) [75], polyalkylcarbonate polyol [20] or mixed blocks of them, for example poly(carbonate-co-ester)diol [76], poly(hexamethylene-carbonate)diol [77], as well as poly(hexamethylene-carbonate-co-caprolactone)diol [78] and a mixed block copolymer of polyether and polyester blocks PCL-b-PTHF-b-PCL [79]. Examples schemes of macrodiols are shown in Eig. 1.9. 

Table 2 Coexistence data of polyethylene (M /(g/mol) = 43700, M ,/(g/mol) = 52000, MJ(g/mol) hydrogenated polybutadiene) in ethene (C2H4) and n-hexane (CeHi4) [2006NAG1]. = 59000,...

Hydrogenated polybutadiene makes polyethylene. In this case, a narrow polydispersity polymer not available otherwise. 

The simplest way to see the difference between the temperature dependences of ar,a and is from the data on high molecular weight polyethylene and hydrogenated polybutadiene [155]. These flexible polymers have low TgS and their viscosities have Arrhenius temperature dependences instead of the WLF dependence at rheological-measurement temperatures. The Arrhenius temperature dependence is basically characterized by its activation enthalpy Ea,t]- Polyethylene has Ea,t] = 26.8 kJ mols [156]. On the other hand, NMR measurements of polyethylene at high temperatures in the picosecond range [157] revealed that the local segmental relaxation is best described by an exponential correlation function. 

Equation (17) suggests that the present treatment, if applied to a polyethylene sample with a small but significant number of very short side chains per chain, should yield a small value for r]. One of the polyethylene samples was a hydrogenated polybutadiene with a small amount of 1-2 addition, and should contain a few ethyl branches. This sample indeed yielded the smallest value for r],... 

These blends with LDPE were weak and brittle. Adding chlorinated polyethylene, or PE grafted with 26% methyl methacrylate, greatly reduced domain size and increased ultimate elongation [31,107]. Adding hydrogenated polybutadiene-b-styrene-acrylonitrile-b-polybutadiene reduced domain size, increased interfacial adhesion, and improved mechanical properties [204b]. 

With the exception of a few commercial polymers such as polyisobutylene, polybutadiene and styrene-butadiene block copolymers, living polymers are prepared in small quantities under stringent conditions. Larger amounts can only be prepared by repeating the synthesis many times, and this is a costly and time-consuming process. In the case of hydrogenated polybutadiene, to prepare samples that resemble polyethylene, the need for a secondary reaction step renders the preparation even more costly. This has so far limited the extent to which it has been possible to use these materials to test models. Cell et al. [ 18] prepared asymmetric stars with structures similar to ethylene-propylene copolymers by hydrogenation of star-branched polyisoprene. The reactions to produce these materials took up to three weeks, and... 

Figure 11.3 Morphology map for nonisothermally crystallized ethylene copolymers, drawn schematically based on experimental data for fractions of linear low density polyethylene and hydrogenated polybutadienes. Spherulitic superstructure is observed within the domeshaped region defined by the three axes eopolymer molecular weight (M), branch content, and nominal crystallization temperature. Reprinted with permission from Reference [23]. Copyright 1981 American Chemical Society.

In many ways, crystallization of statistical copolymers resembles that of homopolymers [65, 68-70]. For example, hydrogenated polybutadienes of different branch content and molecular weight show sigmoidal crystallization isotherms, similar to those seen in polyethylene homopolymer crystallization. In addition, at a given isothermal crystallization temperature, the degree of copolymer crystallinity drops above a critical molecular weight, also qualitatively similar to polyethylene homopolymer [69]. 

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