- - - 2,847,398 United States Patent Office Patented Aug. 2, 1958

2. thereover, the process being effected at conditions nor mally leading to a netted cross-linked polyethylene un 2,847,398 suitable for commercial use. Further objects and ad WNYLENE CARBONATREETHYLENE COPOELY. vantages of the invention will be apparent to one skilled MER AND METHOD OF PRODUCING SAME 5 in the art from the accompanying disclosure and discus Earl W. Gluesenkamp and John D. Caifee, Dayton, Ohio, SIO assignors to Monsanto Chemical Company, St. Louis, The present invention provides new copolymers. Mo., a corporation of Delaware These copolymers are the copolymers of ethylene with vinylene carbonate. Properties of vinylene carbonate No Drawing. Application May 18, 1953 and methods of preparing same are described by New Seria No. 355,859 man and Addor, Jour. Amer. Chem. Soc. 75, 1263, March 5 Claims. (C. 260-77.5) 5, 1953. Vinylene carbonate has the structural for mula: This invention relates to new copolymers and to meth 5 ods of making same. In one of its aspects the inven tion pertains to an improved polyethylene-type material. "" In another aspect the invention pertains to a method of o polymerization. A suitable method of preparing vinylene carbonate is It has long been known to subject ethylene to poly 20 chlorination of ethylene carbonate to form monochloro merization at high pressures of the order of at least ethylene carbonate, followed by dehydrochlorination of 5,000 pounds and often up to 40,000 or 50,000 pounds the latter by reaction with an amine, resulting in vinylene per square inch, with or without the use of small amounts carbonate. of oxygen or organic peroxide catalysts, thereby pro The invention encompasses ethylene/vinylene carbonate ducing a normally solid waxy polymer of high molecular copolymers containing ethylene and vinylene carbonate weight, ranging from 6,000 up to 20,000 or 40,000 and in all proportions. Most copolymers will contain from higher and apparently showing the presence of crystalline 5 to 99 weight percent ethylene and from 95 to 1 weight material by X-ray diffraction analysis. Material prepared percent vinylene carbonate, based upon the combined in this manner and having these general properties is now weights of the monomers entering into the copolymer. commonly termed "polyethylene" and is a very important 30 In its broadest aspects the invention contemplates pro product in the plastics industry. duction of polymers of ethylene containing the Smallest The production of a polyethylene having sufficiently significant quantity of vinylene carbonate, which may be good physical properties to make it a saleable commercial 1 weight percent or less, and at the other extreme the product is not easy. Molecular weight, the presence or production of polymers of vinylene carbonate contain absence of cross-linking and branching, the stability of 35 ing the smallest significant quantity of ethylene which the product towards oxidation and other degradation, the may be 1 weight percent or less, and all proportions be processibility, are all sensitive to farily minor variations in tween those extremes. reaction conditions. Even the best commercial poly Of particular interest are ethylene/vinylene carbonate ethylene leave something to be desired in their physical copolymers containing a major proportion by weight of properties. It would be of great practical importance to ethylene and a minor proportion by weight of vinylene find a simple means of improving such properties, and carbonate combined in the copolymeric material. It is particularly of permitting the production of commercial often preferred to prepare copolymers by polymerization grade polyethylene under reaction conditions which do of a monomeric material comprising ethylene and vinyl not ordinarily give a satisfactory commercial product. ene carbonate, containing a sufficiently high proportion In many applications the appearance of polyethylene is of ethylene to produce a polyethylene-like material, i. e., of little or no importance. However, its cloudiness and a high molecular weight normally solid polymer having lack of surface gloss are severe drawbacks to the com the general properties of polyethylene per se, i. e., poly mercial utilization of polyethylene where the aesthetic ethylene prepared from a monomeric material consisting appeal of the product is important, or where lack of of ethylene. clarity decreases the practical value of the product. Here Any suitable combination of polymerization conditions tofore, satisfactory methods have not been known for resulting in the formation of a copolymer from a mono making comparatively clear polyethylene or polyethylene meric material comprising ethylene and vinylene car having a good surface gloss. bonate can be employed in practicing the invention in An object of this invention is to provide new copoly its broadest as 32cis. -iowever, ia preferred embodiments erS. Another object of the invention is to provide im a monomeric material comprising ethylene and vinylene proved polyethylene-like materials. A further object is carbonate is subjected to copolymerization at high pres to provide a comonomer for ethylene which, when used Sures, preferably at least 5,000 pounds per square inch. along with the ethylene during high pressure polymeriza Pressures of at least 15,000 pounds per square inch are tion, greatly improves the physical properties of the re more preferably employed, resulting in a product having Sulting normally solid polymers. Another object is to 60 high self-compatibility (homogeneity). Often optimum provide a new polymerization process. Still another ob results are obtained at pressures within the range of ject is to produce a polyethylene-like material having a 20,000 to 40,000 pounds per square inch. There is no low elastic memory. Another object is to provide a particular upper pressure limit except that imposed by polyethylene-like material that is stable to thermal proc equipment limitations and pressures up to 200,000 pounds essing treatment. A still further object of the invention 65 per Square inch and even higher are suitable. It will be is to provide a polyethylene-like material that is much understood that suitable precautions should be observed clearer and has much better surface gloss than poly in effecting this polymerization process, including the ethylene per se. A further object is to provide a process use of rupture discs, barriers, and other well-known for polymerizing monomeric mateial comprising ethylene, means for carrying out high pressure reactions with which process produces a polyethylene-like material that 70 safety. It is possible to have a combination of reaction is the equivalent of the best commercial polyethylenes in conditions resulting in an explosive reaction, and this most properties and in some properties is an improvement should be guarded against by known means. However, 2,847,398 3 4 technical facilities for the commercial use of high pressures ized by the presence in the molecule of the group have been adequately developed, and therefore the high -N=N-; the dangling valences can be attached to a pressures employed in this embodiment of the present wide variety of organic radicals, at least one however invention are no barriers to the commercial use of the preferably being attached to a tertiary carbon atom. By high pressure copolymerization process. way of example of suitable azc-type catalysts can be The following discussion is directed particularly to mentioned c,c'-azodiisobutyronitrile, diazcaminobenzene, preferred processes of the invention, wherein high pres aZobis-(diphenylmethane), and c.a.'-azobis-cx, y-dimethyl Sures are employed to effect the copolymerization of eth valeronitrile. The peroxy-type or azo-type polymeriza ylene with vinylene carbonate. However, the invention tion catalyst is used in small but catalytic amounts, which in its broadest aspects encompasses the use of any poly 10 are generally not in excess of 1 percent by weight based merization procedure to effect the copolymerization of upon the monomeric mixture. A suitable quantity is ethylene with vinylene carbonate, and copolymers so often in the range of 0.001 to 0.5 percent by weight. It produced. Will, of course, be understood that one catalyst will not The copolymerization can be carried out at tempera necessarily be the full equivalent of another in all re tures within a fairly broad range, which is preferably 15 Spects. 35 C. to 125 C. The higher temperatures tend to The polymerization can be effected in the presence of result in a discolored product, probably by decomposi Small but catalytic amounts of molecular oxygen. While tion of vinylene carbonate and/or vinylene carbonate this can be supplied in the form of air or other gases units in the polymer molecules. However, in equipment containing molecular oxygen, it is preferred to use essen and at conditions adapted for obtaining rapid copoly 20 tially pure oxygen. The quantity will usually be within merization and satisfactory heat removal, tolerance to the range of 10 to 200 parts oxygen per million parts wards high temperatures is considerably improved. In monomeric material, on the weight basis. any event, a temperature sufficiently high within the The polymerization can also be effected under the in operative range should be used to give a reasonable reac fluence of ionizing radiation of polymerizing intensity in tion rate. The preferred range is 50° C. to 100° C. It 25 accordance with the general procedures described and is an advantage of this invention that such moderate tem claimed in the copending application of William H. Yanko peratures can be used and yet polymers are produced and John D. Califee, Serial No. 318,098, filed October 31, that are readily processible, as opposed to the unduly 1952. Ionizing radiation that can be employed to effect tough and grainy cross-linked and netted polymers made polymerization at high pressures includes ox-radiation and from ethylene at conditions identical except for the ab f3-radiation, but is preferably electromagnetic radiation sence of vinylene carbonate. of high frequency not deflected by electric or magnetic In making a product which is similar to polyethylene fields and of great penetrative value, e. g., gamma rays but with some properties improved, proportions of vinyl and X-rays. Gamma-radiation arising from a radioac ene carbonate within the range of from 1 to 30 weight tive substance, for example, cobalt-60, tantalum-182, po percent of the total monomeric material charged to the 35 tassium-40, etc. is a convenient and preferred source. polymerization are ordinarily preferred. Most frequently Copolymers of ethylene and vinylene carbonate pro in preparing polyethylene-like products, vinylene carbon duced in accordance with the present invention are in ate makes up not over 20 weight percent of the mono clusive of modified polymeric products known as telomers, meric material. obtained by carrying out the copolymerization in the The invention in its broadest aspects is not departed 40 presence of materials which are non-polymerizable un from by providing, in addition to ethylene and vinylene der the conditions employed but which combine with carbonate, other monomeric materials capable of enter a plurality of units of the monomers. The products ob ing into the polymerization reaction. Thus, vinyl chlo tained by such a telomerization or chain-transfer reaction ride, vinyl acetate, vinyl fluoride, propylene, styrene, may be represented by the formula: Y(A)Z, wherein A acrylonitrile, and other unsaturated organic compounds 45 is a divalent radical formed from a polymerizable mix can be used. This, of course, will affect the polymer ture of ethylene and vinylene carbonate and containing properties but the amount can be chosen so as to retain at least one ethylene and at least one vinylene carbon the advantageous results of the copolymerization of ate unit, n is an integer of 2 to 50 or even higher, and Y vinylene carbonate with ethylene. and Z are fragments terminally attached to a chain of Under some conditions ethylene may be copolymerized 50 monomer units, which fragments together form a mole with vinylene carbonate without the use of an added cule of the non-polymerizable compounds such as halo catalyst. However, it is preferred to employ a catalyst genated compounds, e.g., carbon tetrachloride; acids, in an amount sufficient to give a reasonable reaction rate. e.g., isobutyric acid and anhydride; esters, e. g. methyl Suitable catalysts are of the free-radical promoting type, propionate; acetals, e. g., dioxolane; mercaptains, bisul principal among which are peroxide-type polymerization 55 fites, alcohols, ethers, silicon halides, hydrogen chloride catalysts, and azo-type polymerization catalysts. Those and similar compounds. In a similar manner, hydrogen skilled in the art are now fully familiar with a large can be employed in the copolymerization to give a modi number of peroxide-type polymerization catalysts and a fied copolymer of ethylene and vinylene carbonate. suitable one can be chosen readily by simple trial. Such Such quantity of hydrogen is preferably small, for ex catalysts can be inorganic or organic, the latter having the 60 ample, 0.5 weight percent of the monomeric material. general formula: ROOR', wherein R’ is an organic A reaction time chosen for a given copolymerization radical and R' is an organic radical or hydrogen. These will depend, among other things, on the percentage con compounds are broadly termed peroxides, and in a more version desired. While high conversions, approaching specific sense are hydroperoxides when R' is hydrogen. 100 percent of the monomers, are not impossible, it is R’ and R' can be hydrocarbon radicals or organic radi ordinarily much more practical to limit the extent of cals substituted with a great variety of substituents. By conversion to a value appreciably less than 50 weight way of example, suitable peroxide-type catalysts include percent of the monomeric material charged, for example, benzoyl peroxide, tertiary butyl peroxide, tertiary butyl from 10 to 30 percent conversion. Of course, any un hydroperoxide, diacetyl peroxide, diethyl peroxycarbon converted monomers are recovered from the final reac ate, dimethylphenyl hydroperoxymethane (also known 70 tion mixture and recycled, with purification if necessary, as cumene hydroperoxide), among the organic peroxides, to the polymerization, or utilized as charge stock to an hydrogen peroxide, potassium persulfate, perborates and other polymerization. Those skilled in the art will, of other "per' compounds among the inorganic peroxides. course, appreciate that reaction time is one variable The azo-type polymerization catalysts are also well which is interdependent with other reaction variables, known to those skilled in the art. These are character 75 particularly pressure, catalyst, amount of catalyst, purity 2,847,398 6 of monomers, proportions of the monomers, the pres Normally solid thermoplastic copolymers of vinylene ence or absence of added reaction media, and whether carbonate with ethylene made in accordance with the the reaction is a batch or a continuous one. In some present invention can be subjected to conventional in instances it may be desired to employ a reaction time of jection molding and compression molding operations, several days, but ordinarily reaction time not in excess can be cast as films from solvent by known techniques, of about 24 hours is satisfactory. For batch reactions, Solutions of the copolymer can be extruded into various reaction times of 1 to 20 hours are usually preferred. forms including extrusion in the form of fibers or films For continuous reactions, the reaction times are ordi into a non-solvent liquid or into a gas effecting evapora narily much shorter, and they range in a continuous flow tion of solvent, or can be extruded in various forms in system from a few minutes up to a few hours, for ex 0 the absence of any solvent. Some of the copolymers ample, from 1 minute to 5 hours. made in accordance with the invention are particularly The copolymerization of ethylene with vinylene car valuable in making films by the inflated balloon tech bonate can be effected in accordance with the present nique. The polymer can be worked on mills alone or in invention in reaction mixtures consisting solely of eth admixture with other plastic materials in known man ylene, vinylene carbonate, and any catalyst employed. 5 ner. Plasticizers, modifiers, fillers, stabilizers, pigments However, the copolymerization can also be carried out and the like can be incorporated in copolymers made in the presence of added reaction media, for example, in accordance with this invention. It will be appreciated gaseous or liquid carrying fluids, e.g., water, or organic that the characteristics of the numerous copolymers made liquids which may or may not have a solvent action on under varying polymerization conditions and with vary the polymeric product, e. g., acetone, benzene, xylene, 20 ing proportions of ethylene and vinylene carbonate will cyclohexanone, hexane, dioxane, methyl ethyl ketone. cover a wide range. Those skilled in the art, having had The use of added non-reacting fluid reaction media is the benefit of the present disclosure, can choose suitable particularly useful in a continuous flow process. When proportions of ethylene and vinylene carbonate, and water is used as an added reaction medium, it is per suitable polymerization conditions, for producing poly missible to employ additionally suspending and/or emul 25 mers of desired characteristics. High molecular weight sifying agents in Small amounts which aid in the sus normally solid thermoplastic copolymers are preferred, pension or actual emulsification of the monomers and especially those containing a major proportion of ethyl copolymer product in the water. Whether or not such ene and having polyethylene-like characteristics. How materials are used, vigorous agitation is useful, when ever, low molecular weight semi-solid or liquid copoly employing water as a reaction medium, e.g., as by stir 30 mers, made by suitable procedures, for example, telomer ring in a batch reactor, or by use of turbulent flow con ization as described herein-above, are within the broad ditions in a continuous flow polymerization. Liquid re scope of the invention, action media assist in controlling the reaction tempera The following examples provide details of certain ture, since the polymerization is highly exothermic. preferred embodiments of the invention. The data are Suitable proportions of water are, for example, from : to be taken as exemplary, and the invention in its broad 0.5 to 5 parts by weight per part of monomeric ma est aspects is not limited to the particular conditions and terial. If a solvent or a non-solvent liquid organic re proportions set forth therein. action or carrying medium is to be used, ordinarily at least 1 part by weight, up to 5 or 10 parts, will be EXAMPLE 1. suitable. Adequate provision should be made for re 40 moving the exothermic heat of reaction and thus avoid The copolymerization of ethylene with vinylene car ing too severe a temperature build-up during the poly bonate was effected in a high pressure shaker reaction merization. bomb. This bomb was provided with thermocouples to Under suitable conditions, vinylene carbonate mon measure the reaction temperature, and was connected by omer units in the polymeric material can undergo hy. high pressure tubing with a water reservoir, water being drolysis, resulting in the presence of units of the fol 45 used to pressure and to control the pressure on the reac lowing type in the polymer: tion mixture. Into the bomb, surrounded by ice, was placed 0.15 H. E. gram oc,c'-azodiisobutyronitrile as catalyst and 20 grams -C-C- of vinylene carbonate. The bomb was closed, chilled in O O 50 E. E. Dry Ice (solid CO2), and thereafter evacuated while at Dry Ice temperature. The chilled evacuated bomb was The extent of hydrolysis may range from only a very then filled with pure ethylene (approximately 100 grams). small percentage of the vinylene carbonate units in the The thus-filled bomb was placed in the shaker and the polymeric material up to essentially complete hydrolysis, temperature set on automatic control for 55° C. and depending upon the conditions of treatment. When the maintained there for 1 hour while the bomb warmed up polymerization is effected in the presence of water, a to control (shaker) temperature. Meanwhile, the bomb limited amount of hydrolysis can be expected to occur, was pressured with water to 5,000 pounds per square especially if the aqueous medium is acidic or alkaline. inch, after which the connection to the water reservoir Simple polymerization in the presence of water does not was closed. The pressure in the bomb leveled off when appear to effect a great deal of hydrolysis of vinylene 60 the bomb reached 55° C.; the temperature was then carbonate monomer or vinylene carbonate units in the raised to 75 C. After 45 minutes, the pressure rose to polymer. Of course the longer the reaction time the 22,000 pounds per square inch, and then fell rapidly to more extensive the hydrolysis that can be expected to 12,000 pounds per square inch, at which point the pres occur. It may often be desirable to obtain hydrolysis Sure began to level off. The bomb was vented of un of vinylene carbonate units in the polymer. The pres 65 reacted material. On opening the bomb it was found to ence of hydroxyl groups in the polymer provides points contain 30 grams of a white, spongy copolymer of eth for further reaction with all sorts of reagents, and im ylene and vinylene carbonate. parts water-sensitivity to the polymer. In fact, where Analysis of the recovered copolymer showed its oxygen the percentage of vinylene carbonate in the copolymer content to be 6 weight percent, corresponding to 10.7 is sufficiently high a water-soluble polymer can be made 70 weight percent vinylene carbonate units in the copolymer. by hydrolysis. The same methods of hydrolysis can be Properties of the copolymer were determined by stand used on the copolymers described herein as are employed ard plastics testing techniques. In Table I below, the in hydrolyzing vinyl acetate polymers to form polyvinyl thus-obtained data are presented in tabular form, along alcohols. Such methods are numerous and are well side typical data for one of the best commercial poly known in the art. 75 ethylenes. 2,847,398 7 8 EX. Tensile properties Certain test methods, such as density, solubility, etc. A. Strength to yield, p. s. i. are obvious. Other methods used are as follows: B. Strength to break, p. s. i. I. Copper bar thermal properties C. Elongation to yield, percent A. Softening temperature, C. 5 D. Elongation to break, percent B. Melting temperature, C. These tests are determined by the standard tests ASTM The test is performed on a copper bar which is heated D638-46T, D412-41. at one end and cooled at the other, thus forming a surface The comparative data are as follows: whose temperature varies along the bar between these extremes. Thermometers are mounted in the bar at in 0. Table I tervals to determine the temperature of the individual COMPARISON OF PYSICAL PROPERTIES OF ETHYLENEf parts. Particles of the polymer to be tested are sprinkled WINYLENE CARBONATE COPOLYMER WITH COMMER in a thin layer along the bar. After ten minutes the CIAL POLYETHYLENE following observations are made. Ethylene? 5 Physical Property Commercial Vinylene Softening point: This is determined by brushing the Polyethylene Carbonate sample with a bristle of a paint brush. The lowest tem Copolymer perature at which the sample just begins to stick to the bar is taken as the softening point. I. Copper Bar Thermal Properties: Melting point: The lowest temperature at which the A. Softening Temp. C-. 102------05. 20 B. Melting Temp., C.--- 125------120. particles begin to lose their shape is taken as the melting II. Melt index Value: point. A. Extrusion rate, Ing.fsec------2-4------7.7. B. Elastic Memory, percent---- 50-60------53. II. Melt index value II, Earallel Plate Plastometer A. Extrusion rate, milligrams/second A.aa. Viscosity, Poises X 10------0.5-1.5------0.52. B. Elastic memory, percent B. Molecular Weight.------20,000 (ave.)----- 19,000, 25 IV. Modulus Characteristics (Clash-Berg): A steel cylindrical chamber is maintained at 190° C. A. Brittle Temp., if, C------32.0------238. A drilled orifice of 0.063 inch diameter and about 0.6 B. Rubber Temp. T2000, C---- 85.0------82.3. V. Solution Wiscosity: inch length is screwed into the bottom of the cylinder. A. Specific Viscosity, 0.1% in 0.08------0.07. A steel ram carrying a weight on the top is used to Xylene at 210°F. 30 WI. Solubility in Organic Solvents: develop the extrusion pressure on the polymer. The A. Cold (25°C.).------Insoluble------Insoluble, B. Hot (80 C.)------Sol. in xylene, Sol. in xylene, sample to be tested is first mill rolled for five minutes carbon tetra- carbon tetra and then diced in order to give a uniform product free chloride. chloride. from occlusion of gases. After loading the diced parti VII.A. Density: Density at 25°C., g/cc------0.917------0.959. cles into the extrusion chamber and placing the ram VIII. Clarity: thereon, five minutes are allowed for the polymer to 35 A. Visual inspection of Imolding Very hazy and Slightly hazy. reach temperature equilibrium with the chamber. The opaque. IX. A.Surface Visual GloSS: inspection of molding-Semi-dull and Glossy and weight is then applied to the ram and extrusion begins. SOInewhat smooth. The extruding strand is cut at the orifice and a timer rough. started, and the strand then cut a number of times. The X. TensileA. Strength Properties: to yield, p. S. i------i.,200-1,400------1,366. cut strands are weighed and the extrusion rate reported 40 B. Strength to break, p.s. i----- 1,800-2,000------2,229. as milligrams (mgs.) per second. The elastic memory C. Elongation to yield, percent--50------80. determination involves the measurement, by a micrometer, D. Elongation to break, percent- 450-500------470. of the diameter of the extruded strand at the end which is extruded first. The percentage recovery or memory The foregoing data show that the copolymer is gen is calculated as follows: erally comparable to commercial polyethylene in most respects, with certain important improvements thereover. Percentage recovery = Ethylene/vinylene carbonate copolymer is much clearer Measured diameter-orifice diameter than polyethylene. It has a better surface gloss. Addi Orifice diameter X 100 tionally, the ethylene/vinylene carbonate copolymer was 50 very stable to processing treatment, i. e., showed no signs III. Parallel plate plastometer data of thermal decomposition. The milled material had good A. Viscosity, poises X 10-6 flow, as measured by extrusion rate, and had a low elastic B. Molecular weight (weight average) memory. Elastic memory is in the same range as that The Tinius-Olsen parallel plate plastometer is used in of the particular commercial polyethylene described in this determination. Essentially it consists of a system 55 Table I and this value is much lower than that for some whereby a constant force is applied to two parallel plates commercial polyethylene. A low elastic memory is of kept at constant temperature, between which plates a course desirable in the end use of polymer, particularly molded disc of the plastic being tested is placed. Changes extrusion. As to tensile properties, the percent elonga in thickness of the sample are measured over time in tion to yield was better than the commercial polyethylene, 60 as was the strength to break. crements. The test measures the flow of the plastic It will be noted that the foregoing comparison was material under applied stresses at elevated temperatures, made on the basis of commercial polyethylene. An in giving a melt viscosity value, from which approximate portant aspect of the invention is brought out by consid weight average molecular weight can be calculated. eration of the fact that polymerization of ethylene alone V. Modulus characteristics (Clash-Berg)- under the same reaction conditions used for the produc A. Brittle temperature (T), C. tion of the ethylene/vinylene carbonate copolymer of this B. Rubber temperature (T2000), C. example results in a netted cross-linked polyethylene prod This test is a measure of the stiffness of a plastic uct that cannot be processed in commercial equipment specimen as a function of temperature, measured by customarily used for processing polyethylene. means of a torsional test. The test is essentially that EXAMPLE 2. described by Clash and Berg, Industrial and Engineering Chemistry, 34, 1218 (1942). The brittle temperature In the high pressure polymerization apparatus described (T) is the temperature at which the stiffness modulus in Example 1, vinylene carbonate and ethylene were co is 135,000 p.s. i. The rubber temperature (Tagoo) is the polymerized in the manner described in Example 1. The temperature at which the stiffness modulus is 2000. 5 iced bomb was charged with 20 grams vinylene carbonate 2,847,898 9 O and 0.15 gram of c,c'-azodiisobutyronitrile catalyst. The carbonate to copolymerization at a pressure of at least bomb was closed, cooled in Dry Ice, and evacuated, and 15,000 pounds per squire inch and a temperature within then filled with pure ethylene (approximately 100 grams). the range of 50° C. to 100° C. The charged bomb was placed in a shaker and pressured 2. A process which comprises subjecting a monomeric to 5,000 pounds per square inch immediately. When the material comprising from 95 to 70 parts by weight ethyl temperature reached 50° C., the pressure leveled off at ene and from 5 to 30 parts by weight vinylene carbonate approximately 15,000 pounds per square inch. The pres to copolymerization at a pressure of at least 5,000 pounds Sure was then set at 20,000 pounds per square inch on per square inch and a temperature within the range of automatic control for 17 hours. 35° C. to 125° C. The bomb was then discharged, and 6 grams of a O 3. A process which comprises subjecting a monomeric somewhat yellow ethylene/vinylene carbonate copolymer material comprising a major proportion by weight of was recovered. ethylene and a minor proportion by weight of vinylene This application is related to our copending application, carbonate to copolymerization at a pressure of at least Serial No. 550,827, filed December 5, 1955, wherein 5,000 pounds per square inch and a temperature within vinylene carbonate is copolymerized with a halo-sub 5 the range of 35° C. to 125 C. stituted ethylene, said halo-substituted ethylene being an 4. A normally solid polyethylene-like ethylene/vinyl essential component of the monomeric mixture and result ene carbonate copolymer having good surface gloss and ing copolymer. It is also related to our copending ap clarity when molded and obtained by the process of claim plication, Serial No. 550,828, filed December 5, 1955, 3 wherein the monomeric material contains at least 70 wherein vinylene carbonate is homopolymerized or is 20 parts by weight ethylene and not over 30 parts by weight copolymerized with an unsaturated organic compound vinylene carbonate. copolymerizable therewith and having at least three car 5. A copolymer according to claim 4 having at least bon atoms in the molecule, at a pressure of at least 5,000 a portion of the vinylene carbonate units therein hydro pounds per square inch. Said applications Serial No. lyzed. 550,827 and Serial No. 550,828 are continuations-in-part 25 of our now-abandoned copending application, Serial No. References Cited in the file of this patent 355,860, filed May 18, 1953. UNITED STATES PATENTS While the invention has been described with particular reference to various preferred embodiments thereof, it 2,200,429 Perrin et al. ------May 14, 1940 will be appreciated that variations from the details given 30 2,563,771 Adelson ----- as a mm - - - - - w Aug. 7, 1951 herein can be effected without departing from the inven 2,722,525 Price et al. ------Nov. 1, 1955 tion in its broadest aspects. We claim: OTHER REFERENCES 1. A process which comprises subjecting a monomeric Newman et al.: Jour. American Chem. Soc., vol. 75, material consisting of a major proportion by weight of 35 March 5, 1953, pp. 1263 and 1264. ethylene and a minor proportion by weight of vinylene