Carbon-13 nuclear magnetic resonance study of ethylene-1-octene and ethylene-4-methyl-1-pentene copolymers

Detailed assignments of ¹³C n.m.r. signals of ethylene-1-octene and ethylene-4-methyl-1-pentene copolymers, members of the linear low-density polyethylene (LLDPE) family, are presented. The equations relating signal intensities to the monomer sequences are given. Using these equations, the characterization of these copolymers by the triad monomer sequences is possible. From the analysis by the triad sequence, it is suggested that these 1-olefins have a tendency to be present isolated in the copolymer chain.     

Random and block copolymers based on 4-methyl-1-pentene and 1-pentene

The zirconium acetamidinate catalyst {Cp*Zr(Me)₂[N(Et)C(Me)N(tBu)]} (Cp* = ?⁵-C₅Me₅) was used to synthesize both random and block copolymers based on 4-methyl-1-pentene (4M1P) and 1-pentene. The polymers have been characterized by NMR spectroscopy, SEC, DSC, high temperature HPLC and CRYSTAF. Unexpectedly, the yields and molecular weights decreased with increasing amounts of 1-pentene. The reason for this behavior is that 1-pentene occasionally undergoes 2,1-misinsertions trapping the catalyst in a dormant state. These 2,1-misinsertions do not seem to occur with the bulky 4M1P (branched α-olefin). Adding a small amount of ethylene reactivates the catalyst. Unlike most semi-crystalline polymers, the density of the crystalline phase of isotactic P4M1P can be lower than of the amorphous phase, when crystallized under very high pressures. To characterize this peculiar behavior of 4M1P-based polymers, various samples have been subjected to Pressure-Volume-Temperature (PVT) measurements. While the P4M1P homopolymers and block copolymers show the expected decrease in specific volume upon crystallization, the 4M1P-rich random copolymers proved not to vary in specific volume under the same conditions.     

Study of the effect of the monomer pressure on the copolymerization of ethylene with 1-hexene

The effect of ethylene pressure on the copolymerization of ethylene with 1-hexene was studied. The results show an increasing of productivities (g of polymer/n_Zr h) with pressure. This tendency was not observed for the activity (g of polymer/n_Zr h bar) that decreases when pressure is raised. When varing the pressure, the characteristics and properties of the formed copolymers are in accordance with the expectation for changes in the monomer concentration; increasing the pressure causes a decrease in comonomer incorporation. At higher ethylene pressure, the polymer is more crystalline due to less incorporation of 1-hexene and the molecular weight is higher. The density of the copolymers also decreases with comonomer incorporation into the copolymer © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2567–2574, 1997     

13C-NMR study of ethylene/1-hexene and ethylene/1-octene copolymers obtained using homogeneous catalysts

Summary This study employed the ¹³C-NMR spectroscopy to investigate the influence of the increase of the comonomer concentration on the microstruture of ethylene/1-hexene and ethylene/1-octene copolymers obtained by the use of MeSiCp₂ZrCl₂, Cp₂ZrCl₂, Et[Ind]₂ZrCl₂ and [Ind]₂ZrCl₂ catalysts. For both comonomers butyl or hexyl branches were isolated between ethylene blocks. As the -olefin concentration in the copolymer increased, butyl or hexyl branches became closer, some of them, separated by only one or two ethylene units. Incorporation of -olefin in the copolymer was higher for the bridged catalysts, MeSiCp₂ZrCl₂, and Et[Ind]₂ZrCl₂ than for the unbridged ones. The -olefin size did not seem to effect its reactivity towards ethylene.     

从丙烯二聚制4－甲基戊烯－1

用Ｎａ－Ｋ型催化剂，反应温度１４０～１６０℃，反应压力７０～１１０ｋｇ／ｃｍ￣２，液体空速２．０～１．０ｈ￣（－１）时，通过丙烯二聚可制得４－甲基戊烯－１。丙烯二聚反应的最优条件为反应温度１５０℃，反应压力１００ｋｇ／ｃｍ￣２，丙烯液体空速１．０ｈ￣（－１）。此时丙烯的转化率高于４６％，而４－甲基戊烯－１的选择性高于９１％。讨论了反应速度。     

Process for production of pure 4-methyl-1-pentene

A process for the manufacture of pure 4-methyl-1-pentene by catalytic dimerization of propylene has been developed in three stages. The first stage involves preparation of a new process catalyst, which contains metallic sodium and potassium deposited on a Bulgarian natural zeolite, the support having been passivated previously by potassium carbonate. The experimental results demonstrate the advantages of the resulting catalyst over exisisting technology, namely 36% conversion and 92% selectivity relevant to liquid isomers. The second development stage concerns the technological regime of chemical reaction for production of 4-methyl-1-pentene. In the third stage, the regime conditions and equipment ensuring desired quality of the product and utilization of the unreacted propylene returned to the reactor are determined. Based on the studies of all stages, a flowsheet is proposed for synthesis and separation of the reaction mixture of isomeric hexenes to give pure 4-methyl-1-pentene.     

Infra-red study of poly(1-pentene) and poly(4-methyl-1-pentene)

The infra-red (i.r.) spectra of the two polymorphous forms (modification 1 and 2) of isotactic poly(1-pentene) are reported. Several absorption bands characteristic of the two modifications have been detected and attributed to the helical conformation of the polymer chains. The differences between the two modifications are reproducible, thus enabling their identification from i.r. spectroscopy. The infra-red spectra of isotactic poly(4-methyl-1-pentene) is also reported, and compared with that of the atactic polymer. General assignment of absorption bands is presented.     

聚4-甲基-1-戊烯的结构与性能

通过红外光谱、差示扫描量热、力学性能与耐热性能、透光率和动态力学性能测试等测试分析考察了聚4-甲基-1-戊烯(PMP)的结构与性能,并与几种传统工程材料进行对比分析。结果表明:PMP是一种具有优异的透光性和耐热性,且在力学性能、电性能和加工性能方面表现优良的新型聚烯烃树脂。     

Kinetics of the thermal oxidation of poly(4-methyl-1-pentene)

The kinetics of the thermal oxidation of isotactic and atactic poly(4-methyl-1-pentene) were studied in the bulk phase using infra-red (i.r.) spectroscopy. The rates of formation of the non-volatile products were assessed from the i.r. bands of the carbonyl groups at different temperatures and various oxygen concentrations. Reaction temperature varied from 120° to 185°C and oxygen concentrations from 10 to 100%, by volume. A general kinetic scheme and mathematical expressions, previously reported for the thermal oxidation of polyolefins, satisfactorily explained the experimental results. Single activation energies for the major oxidation stages in the scheme, were estimated from various Arrhenius plots.     

聚4-甲基戊烯-1(TPX)的加工和应用

聚4-甲基戊烯-1(TPX)众多的优良性能为其广泛应用奠定了很好的基础。本文重点介绍了TPX的常用加工方法,如注塑成型、挤出成型和吹塑成型等;并综述了TPX在医疗器械、电子电器、包装材料、微孔材料、共混改性等方面的应用。     

XPS characterization of surface fluorinated poly(4-methyl-1-pentene)

The fluorinated surface layer of poly(4-methyl-1-pentene) membranes exposed to a dilute stream of fluorine gas has been characterized with X-ray photoelectron spectroscopy. The concentration and profile of reacted fluorine as a function of exposure time is determined. A computer routine was employed to deconvolute the poorly resolved carbon spectra after various fluorine exposure times. The concentrations of mono-, di-, and trifluorocarbon groups thus determined were used to propose specific structures of PMP at the surface after 1 and 15 min of fluorination. The carbon spectra collected at electron takeoff angles of 15°, 30°, and 90° were also deconvoluted, giving insight into the placement of fluorine as a function of depth. Oxygen is incorporated into the polymer during the fluorination reaction, and the O1s spectra was deconvoluted to determine how the oxygen is bound.     

POSS改性负载型Ziegler-Natta催化剂及其乙烯/1-己烯共聚反应

采用具有开放型骨架结构的大孔SiO₂（Macro-SiO₂）与MgCl₂形成复合载体,同时引入聚倍半硅氧烷（POSS）形成具有空间分隔作用的POSS/MgCl₂纳米团聚体,负载TiCl₄后制备得到改性Ziegler-Natta催化剂。采用红外分析、热重分析、CO低温吸附红外、扫描电镜、粒径分析等手段对POSS改性前后催化剂的结构进行表征,发现POSS的引入能诱导MgCl₂形成更多Mg_4c²⁺缺陷位点,并促进了Lewis酸性位点的形成,有利于TiCl₄有效活性中心的负载。乙烯/1-己烯共聚结果表明,POSS改性催化剂活性较高,最高可达1.03×10⁶ g?（mol?h）^-1,同时具有更高的共聚能力,共聚产物中共聚单体摩尔分数可达3.79%,且聚合产物具有较窄的分子量分布（MWD=3~6）。     

The catalytic characteristic and synthesis technique for 4-methyl-1-pentene over a potassium-supported superbase catalyst

The dimerization of propene to 4-methyl-1-pentene (4MP1) was studied in a fixed-bed reactor at 150?°C temperature, 8?MPa pressure, and 1?h^?1 liquid hourly space velocity (LHSV) in the presence of solid superbase with 20?wt% one-pass conversion to hexene and 88% selectivity toward 4MP1. Based on the reaction results, propene competes with 4MP1 for adsorption on the catalyst surface. A higher reaction pressure or a lower liquid rate of 4MP1, controlled by a suitable propene LHSV or reaction temperature, was beneficial to the adsorption of propene, which reduced the isomerization of 4MP1. Under optimized conditions, propene dimerization was stable for 200?h, and isomerization was limited to less than 5%, yielding products with about 19% one-pass conversion to hexene by weight and 87% selectivity toward 4MP1.     

乙烯四聚制1-辛烯的研究

研究了乙烯选择性四聚制1-辛烯的催化剂体系,利用氯化二苯基膦与胺反应生成二苯基膦胺配体,它与乙酰丙酮铬在助催化剂的存在下显示出较高的催化乙烯四聚的活性和较高的1-辛烯选择性;考察了不同溶剂、温度、压力、n(Al)/n(Cr)及第四组分对催化剂体系的影响,确定了适宜的条件,当n(Cr)/n(PNP)/n(Al)为1∶2∶300,反应温度为30℃,压力为3 MPa时,反应时间为30 min,进行乙烯四聚实验,催化剂活性达58.10 kg/(g·h),1-辛烯的选择性接近70%。     

Effect of several dual solvents on the phase separation of poly(4-methyl-1-pentene)

Phase separation of isotactic poly(4-methyl-1-pentene) (PMP) from various solvents gives polymer masses which can be converted into foams that vary from crumbly powders to well-connected, strong, flexible solids. The composition of the solvent is an important parameter in determining the nature of the separated polymer phase. The influence of solvent (or non-solvent) on the temperature and character of the phase separation event and on the resulting foam structure is addressed in this paper. Thus differing ratios of two poor solvents for PMP, bibenzyl and paraffin, were found to give variable foam structures and surprising phase behaviour. Thermochromism is sometimes observed as the polymer separates.     

Electrostatic polymer processing of isotactic poly(4-methyl-1-pentene) fibrous membrane

Isotactic poly(4-methyl-1-pentene) (P4M1P) is a widely used polymer in industrial applications and specifically, in medical products. Producing micro- or nanofibers would expand the usefulness of P4M1P to a broad range of medical applications. The choice and quality of solvent for the solution used for electrospinning can have a dramatic effect on the spinnability of fibers and on their morphological appearance. In this study, four solvent systems: cyclohexane, cyclohexane/acetone mixture, cyclohexane/dimethyl formamide (DMF) mixture and cyclohexane/acetone/DMF mixture have been investigated. As demonstrated by FE-SEM, electrospun fibers with different morphologies including round, twisted with a roughened texture, curled and twisted-ribbon shapes were formed. The fiber shape and morphology depended strongly on the type and amount of non-solvent used.     

Melt spinning and characterization of hollow fibers from poly(4-methyl-1-pentene)

In this article, the melt spinning behavior of poly(4-methyl-1-pentene) (PMP) hollow fibers (HF) is examined. The melt spinning trials are carried out on a pilot scale melt spinning plant with different settings while a 10-hole 2c-shaped spinneret is used. It is found that the winding speed mainly affects the outer fiber diameter. The influence of different melt spinning parameters is investigated, in particular temperatures, take-up velocities, and the use of quench air. For this purpose, the shape and crystalline structure of the fibers are analyzed using a light microscope, a scanning electron microscope, and wide-angle X-ray scattering. The shape of the fibers is mainly influenced by the temperature settings in the melt spinning process. As a reasonable lower limit, a melt spinning temperature of 280°C is identified. Concerning the crystallinity, a saturation going along with a slight reduction of the polymer chain orientation is observed at elevated take-up velocities.     

碳纳米管对聚4-甲基1-戊烯结晶及力学性能的影响

在聚4-甲基1-戊烯(TPX)中分别加入多壁碳纳米管(MWNT)、羟基化多壁碳纳米管(MWNT-OH)、羧基化多壁碳纳米管(MWNT-COOH),制备了TPX/碳纳米管(CNTs)复合材料。研究了CNTs对复合材料结晶性能与力学性能的影响。结果表明:加入CNTs对TPX的熔点与晶体结构没有影响,但复合材料的结晶度有所降低;加入CNTs可提高复合材料的弹性模量,与MWNT-OH相比,MWNT更能提高复合材料的弹性模量;随着MWNT-COOH含量的增加,TPX/MWNT-COOH复合材料的弹性模量也得到很大提高,当w(MWNT-COOH)为5.0%时,复合材料的弹性模量达257 MPa。     

Solubility of ethylene in 2,2,4-trimethylpentane and 1-octene mixture

With a static type equilibrium cell and the pressure decaying method, the solubility of ethylene in a mixture of 2,2,4-trimethylpentane and 1-octene was measured in the temperature range of 323.15-423.15 K, pressure range of 5-25 bar, and 1-octene concentration from 0 to 85 wt%. The experimental results show that the solubility of ethylene in a 2,2,4-trimethylpentane and 1-octane mixture increases with system pressure but decreases with system temperature.The experimental solubility data were also expressed in the vapor-liquid equilibrium relationship and correlated by the bubble pressure calculation using the Peng-Robinson equation of state (PR EOS) incorporated with the van der Waals one-fluid and the Zhong-Masuoka mixing rules. Among the deviations between the experimental and correlated results, the largest value of average absolute relative deviation is 1.73% for pressure at 423.15 K and that of average absolute deviation is 0.0024 mol fraction for vapor composition at 373.15 K by the Zhong-Masuoka mixing rule.     

Does the length of the short chain branch affect the mechanical properties of linear low density polyethylenes? An investigation based on films of copolymers of ethylene/1-butene, ethylene/1-hexene and ethylene/1-octene synthesized by a single site metallocene catalyst

Three nearly identical linear low density polyethylene resins based on copolymers of ethylene with 1-butene (B), 1-hexene (H) and 1-octene (O) were utilized to investigate the effect of short chain branch length on the mechanical properties of blown and compression molded (quenched and slow cooled) films. The content of short chain comononer in the three copolymers was ca. 2.5-2.9 mol% that corresponded to a density of 0.917-0.918 g/cm³. Within a given series, the tensile properties of these films do not show any significant difference at slow deformation rates (up to 510 mm/min), even though the DSC and TREF profiles of ‘H’ and ‘O’ differed slightly in comparison to ‘B’. However, at higher deformation rates (ca. 1 m/s), the breaking strength of these films was found to increase with increasing short chain branch length. In addition, the Spencer impact and Elmendorf tear strength of the blown films were also observed to increase with increasing short chain branch length. Further, dart impact strength and high-speed puncture resistance (5.1 m/s) of 1-octene and 1-hexene based samples was also observed to be higher than that based on 1-butene. The blown films displayed low and comparable levels of equivalent in-plane birefringence and crystalline orientation by wide angle X-ray scattering. This confirms that the differences in mechanical properties in the blown film series are not attributable to differences in molecular orientation. The deformation behavior of both the compression molded and blown films were also investigated in a well-defined controlled regime by analyzing their essential work of fracture. It was found that the essential work of fracture of films based on 1-hexene and 1-octene was higher than that of films based on 1-butene. While the origin of these differences in mechanical properties with increasing short chain branch length is not fully understood, the present investigation confirms this effect to be pronounced at high deformation rates for both the blown and compression molded quenched films.