Exploring β-Myrcene Incorporation in Propene Copolymerization Using Half-Titanocene Catalysts

Propylene (P) copolymers with a series of cyclic olefins [cyclopentene (CPE), cyclohexene (CHE), cis-cyclooctene (COE), tricyclo[6.2.1.0(2,7)]undeca-4-ene (TCUE), and tetracyclododecene (TCD)] have been prepared in toluene in the presence of phenoxide-modified half-titanocene catalysts, especially Cp’TiCl2(O-2,6-iPr2C6H3) (Cp’ = 1,2,4-Me3C5H2, tBuC5H4), and methylaluminoxane (MAO) cocatalyst. The resultant copolymers are amorphous materials, and their compositions were uniform as confirmed by DSC thermograms [sole glass transition temperatures (Tg)]. The cyclic olefins were incorporated in a 1,2-insertion manner, and the incorporation was affected by the kind of cyclic olefin as well as the nature of catalysts employed. The CHE contents in the copolymers were up to 6.3 mol % (incorporated in an isolated manner), whereas the CPE, COE, TCUE, and TCD contents in the copolymers increased up to ca. 40 mol % (with a mixture of isolated and alternating incorporations) with an increase in the comonomer concentration charged. Linear correlations between Tg values and cyclic olefin contents were demonstrated in all copolymers. The cyclic structure affects the Tg values in the propylene copolymers, except that plots of Tg values vs cyclic olefin contents were close in the P/CPE and P/COE copolymers. In the low cyclic olefin content region (up to 25 mol %), the Tg values in the propylene copolymers were higher than those in the ethylene copolymers.

Influence of comonomer content and short branch length on the physical properties of metallocene propylene copolymers

Preliminary investigation on propylene copolymers with odd carbon number olefin are reviewed. Additional experimental data presents propylene copolymers with 1‐heptene and 1‐nonene having higher impact strength and lower tensile strength values than copolymers of propylene and 1‐pentene.Thermoanalysis shows that the melting temperatures of the different copolymers decreases with increasing comonomer content. Slight changes were observed between the different propylene/1‐heptene copolymer melting and propylene/1‐pentene while the 1‐nonene copolymers show broadening of the melting curves as the comonomer content increases. It was highlighted that the source of novelty for these polymers is the comonomer type and content.

Propylene was copolymerized with the linear α-olefins 1-octene, 1-decene, 1-tetradecene, and 1-octadecene. The metallocene catalyst Me2Si(2-MeBenz[e]Ind)2ZrCl2, in conjunction with methylalumoxane as a cocatalyst, was used to synthesize the copolymers. The copolymers were characterized by 13C and 1H NMR with a solvent mixture of 1,2,4-trichlorobenzene (TCB) and benzene-d6 (9/1) at 100 °C. Thermal analyses were carried out to determine the melting and crystallization temperatures, whereas the molecular weights and molecular weight distributions were determined by gel permeation chromatography with TCB at 140 °C. Glass-transition temperatures were determined with dynamic mechanical analysis. Relationships among the comonomer type and amount of incorporation and the melting/crystallization temperatures, glass-transition temperature, crystallinity, and molecular weight were established. Moreover, up to 3.5% of the comonomer was incorporated, and there was a decrease in the molecular weight with increased comonomer content. Also, the melting and crystallization temperatures decreased as the comonomer content increased, but this relationship was independent of the comonomer type. In contrast, the values for the glass-transition temperature also decreased with increased comonomer content, but the extent of the decrease was dependent on the comonomer type. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4110–4118, 2000

Propylene was copolymerized with the linear α-olefins 1-octene, 1-decene, 1-tetradecene, and 1-octadecene. The metallocene catalyst Me2Si(2-MeBenz[e]Ind)2ZrCl2, in conjunction with methylalumoxane as a cocatalyst, was used to synthesize the copolymers. The copolymers were characterized by 13C and 1H NMR with a solvent mixture of 1,2,4-trichlorobenzene (TCB) and benzene-d6 (9/1) at 100 °C. Thermal analyses were carried out to determine the melting and crystallization temperatures, whereas the molecular weights and molecular weight distributions were determined by gel permeation chromatography with TCB at 140 °C. Glass-transition temperatures were determined with dynamic mechanical analysis. Relationships among the comonomer type and amount of incorporation and the melting/crystallization temperatures, glass-transition temperature, crystallinity, and molecular weight were established. Moreover, up to 3.5% of the comonomer was incorporated, and there was a decrease in the molecular weight with increased comonomer content. Also, the melting and crystallization temperatures decreased as the comonomer content increased, but this relationship was independent of the comonomer type. In contrast, the values for the glass-transition temperature also decreased with increased comonomer content, but the extent of the decrease was dependent on the comonomer type. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4110–4118, 2000

The polarized Raman spectroscopy is employed in the study of structural modifications in the films of isotactic polypropylene (PP) whose chain contains ethylene, 1-butene, 1-hexene, 1-octene, and 4-metyl-pentene-1, which represents an isomer of 1-hexene. It is demonstrated that the phase and conformational compositions of copolymer molecules depend on the comonomer content and the side-chain length of the second monomer. The content of the PP molecules in the helical conformation in the crystalline and amorphous phases of the copolymers monotonically decreases with increasing content of the second monomer. The decrease in the content of helical macromolecules in the crystalline phase is faster than the decrease in the amorphous phase. At a certain content of comonomers, the total content of the helical fragments decreases with increasing length of the side chain of the second monomer. The structures and Raman spectra of the copolymers of propylene with 1-hexene and 4-methyl-1-pentene are similar.

Separation of propene/1-alkene and ethylene/1-alkene copolymers by high-temperature adsorption liquid chromatography

Two sequenced ethylene−propylene (EP) copolymers possessing methyl groups every fifth (EP5) or seventh (EP7) carbon have been prepared using an olefin metathesis polycondensation/hydrogenation strategy, thus generating methyl branched polyolefins with short ethylene run lengths of 4 or 6 carbons, respectively. Precise spacing of methyl branches along both copolymer backbones imparts pristine microstructure and targeted comonomer ratios in the copolymer. Extensive NMR spectral data are presented detailing polymer microstructure, branching analysis, and end-group identification. Thermal analysis using differential scanning calorimetry revealed multiple low-temperature relaxations for EP7 and glass transition temperature of −63 °C for EP5, and FT-IR analysis suggests no crystallinity under ambient conditions. A new ADMET monomer synthesis is also reported for the development of highly functionalized polyolefins or sequenced ethylene copolymers.

The thermal and viscoelastic behaviour of several copolymers of propene and 1-hexene have been studied in a wide range of compositions. The samples were prepared with a Ziegler-Natta catalyst with both internal and external donors. A significant amount of crystallinity has been found for the sample with a comonomer content as high as 19 mol %. The dynamic mechanical results show a considerable decrease of the storage modulus in the copolymers in relation to that of iPP. A single relaxation, corresponding to the glass transition, has been found in all the samples. Only the copolymer with the highest hexene content seems to display the beginning of another relaxation at low temperature.

Measurement and prediction of solubilities and diffusion coefficients of ethylene in rubbery propylene copolymers

Nascent form of random copolymers of propylene with ethylene, 1‐butene, 1‐hexene, 1‐octene, and 4‐methyl‐1‐pentene was studied by Raman spectroscopy. The most significant spectral alterations with a change in propylene content were observed in two lines at 809 and 841 cm−1. The first line corresponds to vibrations of polypropylene helical chains in the crystalline phase, while the second one is associated with vibrations of polypropylene helical chains having isomeric defects. Raman data confirm that conformational composition and phase state of copolymer macromolecules strongly depend on the comonomer content as well as on the size of the comonomer units.

Summary: Copolymers of propylene and hexacosene (Cn = 26–28) were synthesized in the presence of three different metallocene catalysts activated by methylaluminoxane. The poly(propylene) copolymers were prepared with iso‐, syndio‐, and atactic backbone microstructures by using different symmetric metallocenes such as rac‐{Me2Si[2‐Me‐4‐(1‐Naph)Ind]2}ZrCl2 (1), [Ph2C(Cp)(Flu)]ZrCl2 (2), and [(H3C)2Si(9‐Flu)2]ZrCl2 (3) and up to 46.6 mol‐% comonomer content in the feed. The influence of the incorporated linear, ethylene‐based side chains into the poly(propylene) backbone were investigated by DSC, GPC, and 13C NMR. Generally, a decreasing content of comonomer in the feed enhances the activity of metallocene based catalysts. The determination of the branched microstructure by 13C NMR of the copolymers allows a smart identification of the amount of inserted hexacosene because of the separated backbone and side chain signals. Moreover, the relationship between the population of the side chains and the melting behavior of resulting copolymers were discussed. The melting point of the syndiotactic and isotactic poly(propylene) backbone decreases with increasing hexacosene content. When the inserted comonomer content exceeds 2 mol‐%, a second melting point of the crystallized ethylene based side chains can be observed which increases with an increasing amount of hexacosene.Thermal behavior of isospecific hexacosene/propylene copolymers in dependence on the incorporation of hexacosene.magnified imageThermal behavior of isospecific hexacosene/propylene copolymers in dependence on the incorporation of hexacosene.

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10–40mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200–7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (Tm), cold crystallization and glass transition (Tg) decreased with the copolymerization. Tm depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. Tg was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10-40 mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200-7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T m ), cold crystallization and glass transition (T g ) decreased with the copolymerization. T m depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. T g was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.

One of the key factors to a better understanding of the phase morphology of high-impact ethylene–propylene (EP) copolymers is the knowledge of the rheological behaviour of the various phases in these complex systems. Next to the molecular weight distribution, the comonomer content also affects the viscosity, as could be demonstrated in a systematic study of a wide range of compositions. More specifically, this means that for a given average molecular weight, the zero shear viscosity of the disperse phase consisting of amorphous ethylene–propylene ‘rubber’ (EPR) and crystalline polyethylene (PE) of such an impact copolymer are up to orders of magnitude higher than the respective polypropylene (PP) phase. This has a significant effect on the phase morphology and ultimately the mechanical performance of these compositions.