Propylene Terpolymer Research Articles

Polymerization with TMA-protected polar vinyl comonomers. I. Catalyzed by group 4 metal complexes with ?5-type ligands

This paper describes the use of several kinds of group IV Cp based catalyst systems, in the synthesis of co- and terpolymers of ethylene, propylene and α-olefins endowed with OH and COOH functional groups. The hydroxy monomers used were 5-hexen-1-ol (4) and 10-undecen-1-ol (5) and the carboxy monomer was 10-undecen-1-oic acid (6). The three catalyst systems used were the C 2 symmetric ansa-zirconocene (1) the in-site titanium complex (2) and the non-rigid zirconocene (3), all activated by methylaluminoxane. Trimethylaluminium was used to protect the functional group of polar monomers. The first two catalyst systems suffer similar activity loss in the presence of polar monomer whereas the third one exhibited better tolerance toward the hydroxyolefins. NMR and FTIR spectroscopies were used to characterize the polymerization products. All three catalyst systems afforded functionalized co- and terpolymers by direct polymerization of ethylene/propylene/hydroxy-a-olefins but only the catalyst system (1)/MAO displays appreciable activities for direct polymerization of ethylene, propylene and carboxy-α-olefins.

Rheological properties of lonomer based on propylene terpolymer

Ionomers based on terpolymerization of the propylene/1-hexane/10-undecenoic acid system were prepared, and their Theological properties were studied. The complex viscosity increased in the order poly(propylene-co-1-hexene) < homo-polypropylene < terpolymer with acid less than terpolymer with zinc salt, and the crossover modulus of terpolymers with salt or acid were shifted to a lower frequency compared with that of homopolymer. In the G′-G″ plots, terpolymers with salt and acid showed some deviation. So, time-temperature superposition was not applicable to those samples. The flow activation energies showed the following order of value: homopolymer < terpolymer with acid < terpolymer with salt.

Preparations of Propylene and Ethylene Ionomers with Solvay-Type TiCL3 Catalyst

ABSTRACT Terpolymerizations of propylene/1-hexene/ethylchloroaluminurn-10-undecenoate (ECAU) and ethylene/1-hexene/ECAU systems were carried out with Solvay-type TiCl3 and diethylaluminum chloride to prepare the propylene ionomer and ethylene ionomer, respectively. By adding 1-hexene, the ECAU contents of polymer could be enhanced. The acid contents of the propylene terpolymer was higher than that of the etylene one. This indicated polar monomer (ECAU) was incorporated more easily into propylene-based polymer chain. With increasing ECAU in both systems, the rate of terpolymerization decreased while the induction periods of polymerization increased. The propylene terpolymer salts exhibited higher Tm and Tc than the acid form of terpolymers due to the ionic crosslinking of terpolymer salts.

Fullerene grafted amine‐containing polymers

AbstractWe have covalently attached fullerenes to amine containing flexible hydrocarbon polymers such as amino‐ethylene propylene terpolymer (EPDM‐amine) to obtain novel fullerene functionalized polymers. These materials are soluble in solvents such as heptane or tetrahydrofuran (THF), in which the fullerene is essentially insoluble. The reaction of the fullerene and polymer was followed by infra‐red spectroscopy and viscosity measurements. Thermogravimetric analysis (TGA) scans of EPDM‐amine and Fullerene reacted EPDM‐amine show that the fullerene grafted polymer is thermoxidatively more stable than the original polymer. Furthermore, the fullerene grafted polymer could be reacted further with primary‐tertiary diamines to obtain novel polymers in which the fullerene acts as a bridging group for attaching polar functional groups to nonpolar hydrocarbon polymers.

Fullerene functionalized polymers

The recent synthesis and macroscopic isolation of C60 (buckminsterfullerene) has stimulated interest in its properties and chemical reactivity. Fullerenes are known to be attacked by nucleophiles and it has been reported that they react with small amines. There is, however, no report on the reaction of fullerenes with polymeric amines. Fullerenes were found to add to amine containing flexible hydrocarbon polymers such as ethylene propylene terpolymer (EPDM-amine) to obtain novel C60 functionalized polymers. These materials are soluble in common solvents. The reaction of the fullerene and polymer was followed by infra-red spectroscopy and viscosity measurements.

Electrical performance of polymer housed zinc oxide arresters under contaminated conditions

The electrical performance of polymer-housed zinc oxide distribution arresters has been investigated in a fog chamber. Two types of housing materials, copolymers of ethylene and propylene (commonly known as EPM rubber) and terpolymers of ethylene propylene and diene (commonly known as EPDM rubber), both containing alumina trihydrate (ATH) filler, have been examined. It has been demonstrated that, under relatively low (250 mu S/cm) and moderate (1000-2000 mu S/cm) fog conductivity, degradation in the form of tracking and erosion of the housing occurs. On some housings, degradation is dominant in the region of the mold line and is due to nonuniformity in filter dispersion. The electric field has been computed and a few electrode modifications to improve the surface electric field distribution are suggested. >

Hydroperoxidation of EPDM rubber using singlet oxygen: Synthesis and grafting studies

AbstractChemically generated singlet oxygen hydroperoxidizes the ethylidene double bond in terpolymers of ethylene, propylene, and ethylidene norbornene (EPDM rubber). The EPDM–hydroperoxide was reduced exclusively to 2‐(1‐hydroxylethyl)‐norborene‐EPDM rubber using either triphenylphosphine or sodium sulfite. Thermal decomposition of EPDM–hydroperoxide in the presence of either methyl methacrylate or 2‐ or 4‐vinyl pyridine free radically grafted these monomers to the rubber. In the absence of graftable monomer, however, thermal decomposition of EPDM‐hydroperoxide generated an intractable polyether.

Rheological properties, extrudate swell, and die entry extrusion flow marker experiments for rubber–carbon black compounds

AbstractRheological characterization, extrudate swell measurements, and a flow marker extrusion study for several elastomers and their compounds is reported. The materials included natural rubber (NR), styrene–butadiene rubber (SBR), ethylene–propylene terpolymer (EPDM), and polychloroprene (CR) and their carbon black compounds. The shear viscosity was measured with a sandwich rheometer, a shearing disk viscometer, and a capillary rheometer over a wide range of shear rates. Evidence for yield values is found in compounds with 0.20 and 0.30 levels of carbon black. Empirical equations were fit to the data. Extrudate swell measurements were carried out for slit and capillary dies. Increasing the level of carbon black reduces the level of swell. Flow marker experiments were carried out in the barrel of a capillary rheometer using a wide range of die designs. These indicated roughly radial streamline flows into the capillary or slit land. Recessed parts of a die could accumulate stagnant material. Evidence for wall slippage in the rheometer barrel for compounds with 0.20 and 0.30 volume fractions of carbon black is discussed.

Flow of a Generalised Power-Law Fluid in Triangular Dies for Rubber Extrusion

Abstract A theoretical and experimental study of the flow of a rubber compound through dies of equilateral triangular cross-section is presented. To determine the pressure drop in these sections both the variational approach and the finite difference method are used. Velocity profiles for different non-Newtonian indices have been obtained under the assumption that rubber compounds conform to the generalised power-law equation of state. Comparisons between the two methods adopted and experimental data are made. Memory effects which contribute to extrudate swelling are also considered; and a quantitative analysis is carried out in which these effects are used to calculate a minimum die land or preform length. Experimental trials were carried out with an ethylene propylene ter polymer (EPDM) compound and a fair agreement was obtained with theoretical predictions. Also the assumed isothermal conditions were found to conform well with experimental results.

Functional Polymers. L Terpolymers of 10-Undecenoate Derivatives with Ethylene and Propylene

Abstract Terpolymers of 2,6-dimethylphenyl 10-undecenoate with ethylene and propylene have been synthesized. With titanium-based coordination initiator systems, a crystalline terpolymer was obtained which consists of blocks of ethylene and propylene, indicated by two distinct melting transitions. With vanadium-based systems, an amorphous ethylene/ propylene terpolymer was obtained. The crystalline terpolymer was hydrolyzed to the sodium carboxylate salt, which was acidified to give the polymeric carboxylic acid. All polymers were characterized by their infrared,1H-, and 13C-NMR spectra, by differential scanning caiorim-etry, elemental analysis, and dilute-solution viscometry. In addition the polymeric sodium salt was characterized by wide-angle x-ray diffraction.

Flow visualization of blending of elastomers and thermoplastics in an internal mixer

AbstractFlow visualization of blending elastomers and plastics in an internal mixer is described. This is based on observations from front and transverse glass windows placed on the mixer. This enabled us to investigate the flow behavior of pure polymers during the blending operation. The flow behavior was categorized into four regimes which depend on temperature and the polymer. The flow regimes dominate the phase morphology of blends of ethylene–propylene terpolymer and polystyrene. Various rotor designs used in this study creates different two phase morphology due to various flow fields.

Viscoelastic properties of sulfonated ethylene–propylene terpolymer neutralized with zinc cation

AbstractStress–relaxation measurements in uniaxial extension, in the terminal zone, were made of sulfonated ethylene–propylene terpolymer (EPDM), neutralized with zinc cation. The sulfonation levels were 15 to 20 meq/100 g polymer (0.47 and 0.62 mol %), and for each level the effect of the ionic plasticizer, zinc stearate, was investigated. For all the polymers, the decay of the modulus with elapsed time was gradual and featureless, reflecting a broad distribution of relaxation times. Sensitivity of the ionomers' structures to thermal history before an experiment was suggested by irreproducibility in the magnitudes, but not the distribution, of relaxation times at a given temperature. For polymers containing zinc stearate measured at 80°C, the amount of permanent set was low for relaxation up to about 20h, but increased rapidly with additional hours of stretch. Time–temperature superposition did not apply. Composite curves were constructed by matching the stress–relaxation response at short times; moduli measured at long times fell above the composite curve. The shapes of the composite curves were similar, regardless of the level of EPDM sulfonation or the presence of zinc stearate. The apparent Arrhenius activation energy for short‐time relaxation at similar levels of the modulus was about 35 kcal/mol at 140°C for the unplasticized polymers and about 70 kcal/mol at 90°C for the polymers containing zinc stearate, in contrast to the usual effect of plasticizer on the rate of relaxation of amorphous polymers except near the glass transition temperature.

Solution behavior of ionomers. III. Sulfo‐EPDM‐modified hydrocarbon solutions

AbstractThe solution viscosity of polymer thickened hydrocarbons normally decreases markedly as temperature is increased. It has been observed that metal sulfonate ionomers, such as sulfonated ethylene propylene terpolymer, or sulfo‐EPDM, when dissolved in a mixed solvent behave much differently. Specifically, sulfonated ionomers, dissolved in xylene or paraffinic oils with low levels of a polar cosolvent, can provide solutions whose viscosities are either relatively constant or can actually increase with increasing temperature. This isoviscosity effect can be manifested over broad temperature ranges and is mechanistically different from the behavior of conventional polymer solutions. This unusual behavior is explained on the basis of a simple equilibrium involving solvated ion pairs and is shown to be a specific example of a general phenomenon.

Effects of foaming variables on density and morphology of expanded ethylene–propylene terpolymers

AbstractAn experimental study of the relationships between foaming variables and foamed structures of expanded ethylene–propylene terpolymer (EPDM) is reported. The study was carried out using EPDM composition containing azobisformamide blowing agent. The compositions were expanded and cured in hot air into a foamed structure consisting of dense skin and foamed core. The results showed that the foam density, skin thickness, average cell size, and number of cells of the expanded rubbers can be controlled closely by the foaming variables such as residence time, foaming temperature, and blowing agent concentration.

ESR of free radical reactions in gamma‐irradiated ethylene–propylene‐based terpolymers. II

AbstractThe gamma irradiation at liquid nitrogen temperature of dicyclopentadiene, 2‐methylennorbornene, and cyclopentadienyl‐5‐endo‐norbor‐2‐enyl‐methane‐based ethylene–propylene terpolymers leads to the formation of macroradicals of the alkyl type by loss of hydrogen atoms from the ethylene–propylene chains. When warmed almost to glass transition temperature these primary alkyl species decay and generate new radicals by the double‐bond addition and/or H abstraction from the unsaturations. The nature of the radical products was determined by ESR and MO methods.

Bis(diisopropyl)thiophosphoryl sulfides in vulcanization reactions

AbstractA synergistic combination of bis(diisopropyl)thiophosphoryl disulfide, dimorpholyl disulfide, and sulfur is used to produce an efficient vulcanizing system for a range of rubbers. This produces vulcanizates with the exceptional thermal and thermal‐oxidative stability characteristic of sulfur donor vulcanizates and the rapid and extensive crosslinking reaction normally associated with a conventional sulfur–accelerator combination. A pronounced induction period is noted. The crosslinks initially produced in cis‐1,4‐polyisoprene rubbers are predominantly polysulfide but reduce to mono‐ and disulfides at optimum and extended cures. The crosslinks of the ethylene–propylene terpolymer and the styrene–butadiene vulcanizates are initially mainly disulfide but are rapidly reduced to monosulfides at the high curing temperatures (180°C) used. A comparison with vulcanization systems based on tetramethylthiuram disulfide and bis(diisopropyl)thiophosphoryl tri‐and tetrasulfides as sulfur donors and with a conventional cyclohexylbenthazyl‐2‐sulfenamide–sulfur combination, respectively, shows it to have distinct advantages.

Scission and crosslinking during oxidation of peroxide cured EPDM

AbstractThe chemorheology of polymers prepared by peroxide curing terpolymers of ethylene propylene and diene monomer (EPDM) was studied at 375°F in air. Measurements were conducted on terpolymers containing dicyclopentadiene (DCPD), ethylidene norbornene (ENB) or 1,4‐hexadiene (HD) and also on copolymers. Effects of the level of dicyclopentadiene were investigated. A linear relationship is found between crosslinks formed during oxidation and chain scissions. At low termonomer level and in copolymers, this relationship is linear only during the early stages of oxidation. Results are consistent with a kinetic model in which crosslinking sites and scissioning sites on the polymer compete for free radicals which propagate the oxidative chain reaction. Termonomer units apparently act primarily as crosslinking sites with the tendency to crosslink being substantially greater in DCPD than ENB and HD. The number of crosslinks per scission derived from stress relaxation correlates well with elongation to failure retained after air aging 3 days at 350°F. Adjustment of termonomer level can lead to a ratio of crosslinking to scission which strikes a balance between softening of copolymer and embrittlement of some terpolymers at elevated temperature.

Pyrolysis of polyolefin elastomers

Commercial samples of two ethylene—propylene terpolymers (EPDM), two isobutene— isoprene copolymers (IIR), one polyisobutene (PIB) and one chlorosulphonated polyethylene (CSPE) were pyrolysed at temperatures between 770 and 1370 K in a quartz micro-furnace. Volatile products were analysed by gas chromatography using wide-boiling-range and high-boiling-point columns with flame ionisation detectors and/or online quadrupole mass spectrometry using helium as carrier. Low molecular weight gases were separated on a crosslinked polystyrene bead column and detected with a katharo-meter using argon as carrier. Mechanisms are put forward to account for the temperature-dependence of pyrolysis-product yields as follows. In the primary pyrolysis (ca 770–870 K) EPDM products arise principally from 1 : 5 : 9(: 13 : 17) intramolecular hydrogen transfer accompanied by some unzipping. There is also evidence for a small amount of transfer to the third carbon atom and of some β-scission. IIR and PIB yielded isobutene presumably by stepwise cyclic unimolecular elimination. However, a number of other products including telomers, methane, iso-butane and neopentane are explained by telomerisation of isobutene and intramolecular transfer reactions following random scission; at 870 K, there is already evidence for some aromatisation. CSPE pyrolysis is complicated by preliminary loss of SO2Cl groups and dehydrochlorination to form a polyene. Concomitant crosslinking may involve inter-molecular elimination of HCl and/or a Diels-Alder type reaction between two polymer molecules which have already undergone dehydrochlorination. Subsequent thermal degradation of the main chain proceeds principally by 1 : 5 hydrogen transfer. At intermediate temperatures (above 900 K) secondary pyrolysis occurs in which higher alk-l-enes formed by primary pyrolysis break down to lower molecular weight products probably by a modified Rice mechanism and associated intramolecular cyclic dissociation. Similar mechanisms are proposed to explain the secondary products from IIR and CSPE. At higher temperatures (above 1000 K) further fragmentation, cyclisation and aromatisation. occur. For all the polymers, hydrogen yields increase sharply and yields of C3/C4 products diminish; C2 yields show maxima at temperatures about 1100 K. Below 1200 K, benzene is formed in largest yield. Toluene yields fall at temperatures above 1100 K, but naphthalene is formed in increasing yields up to a maximum at about 1220 K. At these higher temperatures, the product spectrum is simplified by the disappearance of molecules of intermediate size leaving only small fragmentation products and rather large polynuclear aromatics (anthracene, etc.). Two main routes are suggested for the formation of cyclic products from EPDM and IIR- a cyclisation of (particularly) methyl-substituted n-alkenes/alkanes of sufficiently high carbon number; and b the reaction of intermediate molecules such as olefin + diene by a Diels-Alder reaction. At the highest temperatures investigated, high hydrogen yields are accompanied by a substantial drop in total yield of volatilisable products and this is attributed to further condensation of aromatics in coking reactions.

Rubber networks containing unattached macromolecules. II. Viscoelastic properties in small strains of the system ethylene–propylene terpolymer with ethylene–propylene copolymer

AbstractMixtures of crosslinkable ethylene–propylene terpolymer with saturated ethylene–propylene copolymer (molecular weights 3.6, 16.7, and 45 × 104) containing up to 50% by weight of copolymer were crosslinked by sulfur, leaving the saturated copolymer unattached and free to reptate in the terpolymer network. Stress relaxation in small simple elongations (stretch ratio about 1.15) and dynamic Young's modulus at frequencies from 3.5 to 110 Hz were measured at temperatures from 10 to 50°C. Comparison with the properties of the terpolymer crosslinked without added copolymer showed contributions to stress relaxation and mechanical loss attributable to the unattached species. The time required in stress relaxation for the portion of the modulus attributable to the unattached species to decay to half its plateau value, t1/2, is approximately proportional to the 3.5 power of the molecular weight; t1/2 appears to be slightly smaller for networks containing 50% than for those containing 25% unattached component.

Rubber networks containing unattached macromolecules. III. Nonlinear stress relaxation in the system ethylene–propylene terpolymer with ethylene–propylene copolymer and behavior of extracted networks

AbstractFurther stress relaxation experiments, mostly at 50°C, are reported on mixtures of crosslinkable ethylene–propylene terpolymer with saturated ethylene–propylene copolymer (molecular weights 3.6 and 45 × 104) containing up to 50% by weight of copolymer, crosslinked by sulfur to leave the saturated copolymer unattached and free to reptate in the copolymer network. Stress relaxation was measured in small simple elongations (stretch ratio about 1.15) on samples which had been extracted to remove a large part of the unattached copolymer and dried. The relative increase in modulus at long times (104 sec) increased with the proportion extracted; at short times (1 sec), extraction of the lower molecular weight copolymer increased the modulus to about the same extent but extraction of the higher molecular weight copolymer affected it very little. The relaxation modulus of the copolymer extracted from sample 50H (50% copolymer of high molecular weight), obtained by difference, agreed with that for the total copolymer except for a small difference probably attributable to molecular weight selectivity in the extraction. Stress relaxation was measured on sample 50H at six higher elongations up to a stretch ratio of 3. The dependence of stress on time and strain was consistent with an analysis based on the following assumptions: (a) linear additivity of the network and unattached copolymer contributions, (b) strain–time factorization of the stress contributions from the individual components, (c) a strain dependence for the unattached component corresponding to the presence of a Mooney–Rivlin C2 term only, (d) a strain dependence for the network component which does not follow the Mooney–Rivlin equation but is dominated by a simple neo‐Hookean term.