Model copolymers of ethylene with butene‐1 made by hydrogenation of polybutadiene: Chemical composition and selected physical properties

Abstract

Hydrogenation of polybutadienes with from 8 to nearly 100% vinyl content was used to prepare a series of model copolymers of ethylene and butene‐1 with uniform microstructures and narrow molecular weight distributions. They range from readily crystallizable to completely amorphous, depending on the frequency of ethyl side branches (2–50 per 100 skeletal carbons). Melting temperature, secondary transition temperature, density, plateau modulus for the melt, and elastic modulus for the solid were obtained as functions of branch content. The effect of crystallinity on the secondary transition and modulus of the solid is discussed.

Crystallization of tethered polyethylene in confined geometries

“…However, the measured PE crystallinity of this sample is consistent with previous reports of the crystallinity of hydrogenated polybutadienes of similar ethyl branch content. 27,57 The calculated crystallinities of the EV diblocks are slightly less than that of the E-1 homopolymer, and appear to be essentially independent of the polymer composition.…”

“…27,57 As shown in Figure 7, the PE components of the EV diblock samples melt at lower temperatures than the E-1 homopolymer, with a reduction in T m occurring as the PE weight fraction is decreased. Based on the data presented in Table I, it may also be noted that this drop in T m occurs as the molecular weight of the PE block is decreased.…”

Crystal thickness distributions from melting homopolymers or random copolymers

“…Model ethylene-butene copolymers are hydrogenated polybutadienes, the synthesis and characterization of which were described earlier. 6,19 All polymers are described in Table II. HPB-20 and HPB-49 have 20 and 49 ethyl branches per 1000 backbone carbon atoms, and are the same as EB-20 and EB-49 in Table I.…”

SSA study of early polyethylenes degradation stages. Effects of attack rate, of average branch length, and of backbone polymethylene sequences length distributions

“…Hydrogenated Polybutadiene (HPB) is here used as a model linear polyethylene with statistically distributed short branching and homogeneous intra-and intermolecular chemical composition distributions. HPBs have also been well established as model copolymers with very narrow molecular weight and chemical composition distributions [13]. Low-density polyethylene (LDPE) is here used as a typical polymer with randomly placed long branching, even while it also has some short branching; the ratio of long to short branching depends on the details of the polymerization process.…”