Showing papers by "DSM published in 1984"

Mark–Houwink equation and GPC calibration for linear short‐chain branched polyolefines, including polypropylene and ethylene–propylene copolymers

Abstract: The reduction in molecular dimensions due to the presence of short side chains in otherwise linear polyolefins can very simply by calculated by assuming that the configuration of the main chain is not influenced by the side chains. This enables us to express the intrinsic viscosity–molar mass relationship as a function of the mass fraction of side chains (S): [η] = (1 − S)α+1KPEMνα and, with use of the universal calibration principle, to convert the GPC calibration for purely linear polymers samples into the calibration for short-chain branched polymers: M* = (1 − S)M. Experimental data from literature on short-chain branched poly-ethylenes, and our own data on ethylene–propylene copolymers are used to verify the above assumption. It appears that the experimentally found relations between [η], Mw and M*w (GPC) within the usual accuracy justify this approach.

Crystallization and melting behavior of polyethylene fractions obtained by various fractionation methods

Abstract: A high density polyethylene (HDPE) and a low density polyethylene (LDPE) were fractionated by means of preparative GPC, analytical GPC, direct extraction, and a crystallization/dissolution method, to enable determination of the chain branching distribution over the molar mass distribution. The non-isothermal crystallization and melting behaviour of the HDPE and LDPE fractions and of a series of linear polyethylene (LPE) fractions was studied using DSC with a scanning rate of 5 K/min. After an initial increase, the crystallization temperature of the LPE fractions started to decrease at M−20 kg/mol, to remain at a constant value from M−60 kg/mol. This is illustrative of the crystallization being hindered by entanglements. With LDPE fractions showing a constant degree of short chain branching an analogous, but greater, decrease was observed in a corresponding range of molecular dimensions. The differences found for the HDPE fractions as compared with the LPE reference values are due mainly to short chain branching.

Gradient elution chromatography of polymers on reversed-phase columns with tetrahydrofuran as an eluent component

Abstract: The chromatographic separation of poly(styrene-co-acrylonitrile) samples (SAN) with an elution gradient iso-octane/tetrahydrofuran is solubility governed. This has been proven by the correspondence between the volume fraction of precipitant as estimated from elution data and as measured by turbidimetric titration, by the molar mass dependence of retention, and by the temperature effect on retention. In addition to these arguments data are presented which have been obtained on columns with different packing materials ranging from bare silica through CN bonded phase material to hydrocarbonaceous stationary phases. The eluent composition at peak position is nearly independent of the stationary phase used.

Laminates on the basis of polypropylene and process for preparing such laminates

Abstract: The invention accords to a laminate at least consisting of a first layer from a mixture of at least a propylene polymer and an ethylene-vinylalcohol copolymer and a second layer from at least one propylene polymer, the first layer at least consisting of a mixture of 60-99 parts by weight of a substantially crystalline propylene polymer and 1-40 parts by weight of an ethylene-vinylalcohol copolymer, the second layer at least consisting of a substantially crystalline propylene polymer, the said ethylene-vinylalcohol copolymer having a melting temperature at atmospheric pressure which is at most equal to and not more than 30 K lower then the melting temperature at atmospheric pressure of the one of the substantially crystalline propylene polymers used having the highest melting temperature, and the laminate having been subjected to multi-axial stretching to a degree of at least twice in at least 2 directions at a temperature which at most equals the melting temperature of the one of the substantially crystalline propylene polymers used having the highest melting temperature and to a process for preparing such a laminate.

Liquid‐liquid phase separation in multicomponent polymer systems, 21. Deuterium isotope effect in polymer compatibility

Abstract: The spinodal and, hence, the miscibility gap of relatively short chain polystyrene/polybutadiene (PS/PB) mixtures is shifted by 14°C towards higher temperatures, if the hydrogen in PB is replaced by deuterium. The shift corresponds to a difference in the heat of mixing of about 0,2 kJ per mole of styrene units for a 1:1 PS/PB mixture. The effect has been observed by means of Gordon's Pulse Induced Critical Scattering method and the resulting spinodals are found to differ also with respect to the location of their maximum which indicates disparity in the entropy of mixing. For the prediction of the spinodal in a polystyrene/polybutadiene/perdeutereous polybutadiene (PS/PBH/PBD6) system the assumption of non-athermal mixing in PBH/PBD6 is needed. The value estimated for the PBH/PBD6 interaction parameter involves the second viral coefficient for solutions of PBD6 in PBH to be very close to zero. Expressions are presented for the second virial coefficient in quasiternary systems by scattering methods.

Recovery of caprolactam from caprolactam-containing distillation residue

Abstract: Process the recovering caprolactam from the residue remaining following the distillation, under reduced pressure, of impure caprolactam obtained by rearrangement of cyclohexanone oxime with sulphuric acid or oleum, by distilling the residue under reduced pressure whereby a caprolactam-containing distillate is obtained; hydrogenating the caprolactam containing distillate in an aqueous medium to obtain a hydrogenation product; and recovering caprolactam from the resulting hydrogenation product.

N-substituted carbamoyl-lactam compound

Abstract: OF THE DISCLOSUREThe invention concerns N-substituted carbamoyl-lactam compounds of the formula where:- R is a polyol radical from a polyol having the formula R-(-OH)xi, where Xi is an integer ? 2, - R' is an alkyl, whether or not cyclic, aralkyl, alkaryl or aryl group, .gamma.i is an integer > O, - (-L) is an unopened lactam ring and - (-L-) is an opened lactam block. These compounds are useful in the preparation of highly impact resistant nylon block copolymers.

Process for the preparation of an n-substituted carbamoyllactam compound

Abstract: The invention concerns a simple, reliable and reproducable process for the preparation of an N-substituted carbamoyl lactam compound, for example of the following formula: where: - R is a polyol originating from a polyol having the formula R-(OH) xi , where - is an integer ≥ 2 - R is an alkyl, aralkyl, alkaryl or aryl group, whether or not cyclic, - yi is an integer ≥ 0, - (-L) is an unopened lactam ring and - (-L-) is an opened lactam block. This process is characterized in that a polyol and a lactam blocked polyisocyanate are reacted in the liquid state in the presence of a metal compound catalyst.

Model Vulcanization of EPDM Compounds—Part I: Structure Determination of Vulcanization Products from Ethylidene Norbornane

Abstract: Vulcanization of ENBH (C9H14), a model for ENB containing EPDM rubber, with a system consisting of zinc oxide, stearic acid, sulfur, TMTD, and MBT at 140°C for 1 h yields slightly more than 30 different crosslinked products C9H13-Sn-C9H13 where n=2,3,4, and 5. In all of the products, the original ENBH structure is maintained (no shift of the double bond) and attachment of the sulfur bridge occurs only at the two allylic positions 3 and 9. Monosulfides (n=1) are probably also formed but no structures could be determined. Only small amounts of the MBT-Sn-C9H13 coupling products and noncrosslinked cyclic sulfides are formed.

Linear thermoviscoelasticity and characterization of noncrystalline EPDM rubber networks

Abstract: Etude experimentale afin de montrer comment la superposition temps-temperature et les caracteristiques viscoelastiques lineaires varient avec le degre de reticulation pour une classe large de reseaux EPDM non cristallins vulcanises par un peroxyde

Cross-linked nylon block copolymers

Abstract: A nylon block copolymer prepared from acyl lactam functionalized materials and lactam monomer and cross-linked by a polyfunctional amine.

Process for purifying a rubber

Abstract: The invention relates to a process for purifying ethylene-alkene-diene rubbers by extraction with an extractant chosen from substances with a critical temperature below 435° K. at a temperature above the critical temperature of the extractant and a pressure above the critical pressure of the extractant.

Solubility of Solids in Supercritical Solvents I. General Principles (Invited Lecture)

Abstract: Solubility of solids in supercritical solvents is not essentially different from equilibrium crystallisation/solubility behaviour in normal liquids, except for the highly non-ideal nature of nearcritical fluid mixtures. It can be shown quite generally that interactions in the fluid phase play a predominant role both at the first and the second critical endpoints in a binary system. Further factors of importance, particularly at the second critical endpoint, are the solute's heat of fusion and the location of its triplepoint compared with that of the critical point of the solvent. In the separation of two solid components ternary critical endpoint behaviour and the location of the ternary eutectic further determine the selectivity of the extraction. The mean-field lattice-gas model provides a useful tool to describe and predict fluid phase behaviour around critical points.

Compositions containing maleimide-amide compounds as well as the preparation and application thereof

Abstract: The invention relates to compositions containing 80-30 weight % of bismaleimide-compounds, 5-60 weight % maleimide-amide compounds and 1-10 weight % maleic anhydride derivative. The invention further relates to the preparation of such compositions and to homogeneous curable compositions comprising bismaleimide/maleimide-amide/maleic anhydride compositions according to the invention. The obtained copolymers show good chemical resistance and a high heat distortion temperature.

Column Liquid Chromatography of Reducing Carbohydrates by Fluorometric Reaction Detection with a Pressurized Reactor Outlet

Abstract: The use of reaction detection In column liquid chromatography Is not always precluded by the limitation of the reaction time to one or two minutes. A closed pressurized reactor allows heating of the reaction mixture to temperatures that exceed the boiling point of the mixture to enhance reaction speed.

Cross-linked nylon block copolymers and process of their preparation

Abstract: A nylon block copolymer prepared from acyl lactam functionalized materials and lactam monomer and cross-linked by a polyfunctional amine.

The Effect of Variations in Chain Connectivity on Strain-Induced Crystallization in Unvulcanized EPDM Elastomers

Abstract: The introduction of a small amount of chemical or physical crosslinks has an enhancing effect on SIC in EPDM. This situation results from a decrease in stress relaxation or creep, so that the individual chains are deformed more affinely. At the same time, there is no deleterious effect of crosslinks on the crystallization of nonstretched EPDM because of its copolymeric nature. Therefore, the higher connected chains have a smaller melting entropy upon stretching, which promotes the crystallization process. In both EPDM green rubbers and black compounds, the amount of crystallinity and the end-melting temperature increase considerably with strain, in contrast to literature reports. These are desirable qualities for rubber tack. In spite of the positive effect of a higher chain connectivity on SIC, chain connectivity has a detrimental influence on tack. This effect is the result of a drastic reduction in bond formation caused by diminished material flowability and chain interdiffusion. Hence, we con...

Model Vulcanization of EPDM Compounds—Part II: Influence of Temperature and Time on the Vulcanization Products from Ethylidene Norbornane

Abstract: Influence of vulcanization temperature and time on the sulfur crosslinks in vulcanized EPDM (third monomer ENB) was studied using the low-moleular model compound ENBH (C9H14). For each vulcanization condition (60 min at 180°, 160°, 140°, and 120° and 60, 30, 15, and 5 min at 140°), the nature of the crosslinks is represented by the composition of the C9H13−Sn−C9H13 vulcanization mixture as indicated by its HPLC chromatogram. In this way it is shown that increase in temperature favors formation of disulfidic crosslinks at the expense of the higher-sulfide crosslinks. Under the mildest vulcanization conditions (60 min at 120° or 5 min at 140°), disulfidic crosslinks are nearly absent and penta-sulfidic crosslinks are the most important.

Process for preparing an oxidation catalyst

Abstract: This invention provides a catalyst composition suitable for the gas phase oxidation, ammoxidation and oxidative dehydrogenation of olefins to unsaturated aldehydes, unsaturated nitriles and dienes respectively. The catalyst composition comprises, as active catalyst component, a solid solution of Fe, Sb and Ti oxides which has a rutile type crystal structure which is present in the composition in an amount of at least 80 wt. %, and which is represented by the empirical formula Fe x Sb y Ti z O w , wherein, for x=1, y is in the range of 0.5 to 10, z is in the range of 0.16 to 209 and w represents the number of oxygen atoms corresponding to the oxides of the above elements. The catalyst component is prepared by co-precipitating metal oxides from solutions of corresponding metal salts followed by calcination at 600°-1000° C. of the washed and dried precipitate.

Process for preparing polyacrylonitrile articles having high tensile strength and modulus

Abstract: Polyacrylonitrile articles, such as filaments, tapes and films, having high tensile strength and modulus, and prepared by adding to a solution of polyacrilontrile with a molecular weight above 3 x 10 5 , pref. above 5 x 10 5 , a minor amount of a bivalent metal compound, converting the solution into a solvent containing article, cooling this article to form a gelarticle, removing from this gel the solvent and metal compound, and stretching the resulting article at increased temperature. With this process filaments with a tensile strength above 1.2 GPa and a modulus above 16 GPa can be obtained.

Process for preparing nylon block copolymers and composition for use in the same

Abstract: PROCESS FOR PREPARING NYLON BLOCK COPOLYMER AND COMPOSITION FOR USE IN THE SAME ABSTRACT OF THE DISCLOSURE A process for preparing a nylon-6 block copolymer in which a solution comprising an acyl-lactam, epsilon-caprolactam and magnesium chloride is brought into reactive admixture with a solution of magnesium dilactam in epsilon-caprolactam. The acyl-lactam magnesium chloride solution is prepared by reaction of an acid halide functional material and magnesium dilactam.

Process for the (co)polymerization of ethylene

Abstract: n improved process for the preparation of a catalyst for the polymerization of ethylene, and an improved process for preparing an ethylene polymer therewith. An improved catalyst is prepared by mixing an aluminium halide and a magnesium compound at a temperature below 100°C and in the absence of monomer(s), their ratio being such that the molar ratio between halogen and magnesium is from 2:1 to 20:1, mixing an alcohol with the mixture of the aluminium halide and the magnesium compound, this also being effected at below 100°C and in the absence of monomer(s), the amounts used being such that the molar ratio between alcohol and hydrocarbyl groups bound to magnesium and aluminium is from 0.1 to 0.9, and by adding after mixing of the aluminium compound and the magnesium compound and before, simultaneously with or after combining with the alcohol, a titanium compound, the amounts added being such that the molar ratio between magnesium and titanium is from 2:1 to 200:1. The improved polymerization process is carried out at at least 180°C.

Microbore columns in quantitative column liquid chromatography

Abstract: Some quantitative implications of the use of microbore columns in column liquid chromatography are investigated. Although for several pumps the flow rate stability at 50 μl min−1 is slightly worse than that of pumps operating at 1 ml min−1, the quantitative performance with respect to repeatability and reproducibility of response factors equals that of conventional liquid chromatography. Thermostatting is strongly recommended for microbore column operation.

Process for the production of an object from an ABS-polymer composition

Abstract: The invention relates to a process for the production of an object from a granular ABS polymer composition, said composition comprising a mixture of I 10-98 parts by weight of one or more graft copolymers obtained by polymerizing a mixture of one or more unsaturated nitriles and one or more vinylaromatic compounds in the presence of a rubber. II 2-90 parts by weight of a copolymer of one or more unsaturated nitriles and one or more vinylaromatic compounds, and III 0-20 parts by weight of one or more additives, wherein the polymer composition is melted, homogenized, and extruded or injection molded into an object. To improve the flow properties of the mixture introduced into the processing equipment and the throughput of this equipment the invention is characterized in that the ratio between the average particle size (by weight) of the copolymer II to the average particle size (by weight) of the graft copolymer I exceeds 1.5.

Process for preparing an impact-resistant ethylene-propylene block copolymer

Abstract: Present invention pertains to a process for preparing an impact-resistant ethylene-propylene block copolymer, characterized in that in a first polymerization step a propylene prepolymer is prepared consisting for at least 98% (wt) of propylene groups having a melt index measured according to ASTM-D-1238 at 503K and 21.6 N of 0.1-100 dg/min, in that in the presence of the propylene prepolymer produced in the first polymerization step ethylene and propylene are polymerized in a second polymerization step in such a manner that a starting ethylene-propylene block copolymer is formed at least consisting of an at least almost completely homopolymeric propylene part and a copolymeric ethylene-propylene part, the weight ratio between the at least almost completely homopolymeric propylene part and the copolymeric ethylene-propylene part being between 3:2 and 9:1, containing a total amount of 10-25% (wt) ethylene groups and having a melt index measured according to ASTM-D-1238 at 503K and 21.6 N which is 1/100 to ½part of the melt index measured according to ASTM-D-1238 at 503K and 21.6 N of the propylene prepolymer and in that this starting ethylene-propylene block copolymer is subsequently subjected to a kneading treatment consisting of one or more kneading operations, which kneading treatment takes place in the presence of free radicals at a temperature of a least 450K.