WO2005066255A1

WO2005066255A1 - Method for absorbing oxygen from a gas mixture within an enclosure

Info

Publication number: WO2005066255A1
Application number: PCT/IB2004/003787
Authority: WO
Inventors: Cheng Q. Song
Original assignee: Basell Poliolefine Italia S.R.L.
Priority date: 2003-12-31
Filing date: 2004-11-12
Publication date: 2005-07-21
Also published as: TW200533408A

Abstract

A method for absorbing oxygen from a gas mixture within an enclosure, the method comprising exposing a gas mixture to an oxidized propylene polymer material having a peroxide concentration of about 1 to about 200 mmol total peroxide per kilogram of oxidized propylene polymer material, wherein the oxygen is absorbed by the oxidized propylene polymer material.

Description

METHOD FOR ABSORBING OXYGEN FROM A GAS MIXTURE WITHIN AN ENCLOSURE The present invention relates to the use of oxidized propylene polymers for absorbing oxygen from gas mixtures contained within enclosures. The detrimental aspects of oxygen in certain industrial and commercial applications are well known. For example, in manufacturing processes, maintaining desirably low oxygen concentrations in equipment is important for controlling corrosion. In the food packaging area, controlling the exposure of oxygen-sensitive products to oxygen maintains product quality and increases the food product's shelf-life, thereby allowing the product to be kept in inventory longer, and reduces costs associated with waste disposal and re-stocking. One method for minimizing oxygen contact in commercial applications such as food packaging has involved using passive barriers such as metals, glass or various plastics such as polyvinylidene chloride. However, while these methods may protect the food from contact with oxygen present outside the container, they do not affect oxygen contained in the gas space surrounding material within the enclosure, or from leakage around connections or seals on the enclosure. To address this, various methods have been used to actively absorb oxygen. In U.S. Patent 5,958,254, organic compounds that are capable of being reduced, such as quinones, were incorporated into polymer compositions. Oxygen scavenging layers containing an oxidizable organic compound and photoinitiator have been described in U.S. Patent No. 6,517,776. However, there continues to be a need for cost-effective oxygen absorbing materials. It has unexpectedly been found that oxidized propylene polymer material can be used in a process to absorb oxygen in a gas mixture contained within an enclosure. The present invention relates to a method for absorbing oxygen from a gas mixture within an enclosure, the method comprising exposing a gas mixture to an oxidized propylene polymer material having a peroxide concentration of about 1 to about 200 mmol total peroxide per kilogram of oxidized propylene polymer material, wherein oxygen is absorbed by the oxidized propylene polymer material. The method of the present invention utilizes an oxidized propylene polymer material to absorb oxygen from a gas mixture surrounding it. The oxidized propylene polymer material maybe prepared by subjecting a propylene polymer to an ionizing radiation followed by oxidation or by means of organic peroxide initiators, as described in the following. The propylene polymer used as the starting material for the oxidized propylene polymer material can be: (A) a homopolymer of propylene having an isotactic index greater than about 80%, preferably greater than about 90%; (B) a random copolymer of propylene and an olefin chosen from ethylene and C₄- C₁₀ α-olefins, containing about 1 to about 30 wt% of said olefin, preferably about 2 to 20 wt%, and having an isotactic index greater than about 60%, preferably greater than about 70%; (C) a random terpolymer of propylene and two olefins chosen from ethylene and C -C₈ α-olefins, containing about 1 to about 30 wt% of said olefins, preferably about 2 to 20 wt%, and having an isotactic index greater than about 60%, preferably greater than about 70%; (D) an olefin polymer composition comprising: (i) about 10 parts to about 60 parts by weight, preferably about 15 parts to about 55 parts, of a propylene homopolymer having an isotactic index of at least about 80%, preferably greater than about 90%, or a crystalline copolymer chosen from (a) propylene and ethylene, (b) propylene, ethylene and a C₄-C₈ α-olefin, and (c) propylene and a C₄-C₈ α-olefm, the copolymer having a propylene content of more than about 85% by weight, preferably about 90% to about 99%, and an isotactic index greater than about 6O%; (ii) about 3 parts to about 25 parts by weight, preferably about 5 parts to about 20 parts, of a copolymer of ethylene and propylene or a C₄-C₈ - olefin that is insoluble in xylene at ambient temperature; and (iii) about 10 parts to about 85 parts by weight, preferably about 15 parts to about 65 parts, of an elastomeric copolymer chosen from (a) ethylene and propylene, (b) ethylene, propylene, and a C₄-C₈ α-olefin, and (c) ethylene and a C -C₈ α-olefm, the copolymer optionally containing about 0.5% to about 10% by weight of a diene, and containing less than about 70% by weight, preferably about 10% to about 60%, most preferably about 12% to about 55%, of ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity of about 1.5 to about 6.0 dl/g, the total of (ii) and (iii), based on the total olefin polymer composition being from about 50% to about 90% by weight, and the weight ratio of (ii)/(iii) being less than about 0.4, preferably about 0.1 to about 0.3, wherein the composition is preferably prepared by polymerization in at least two stages; and (E) mixtures thereof. In one method for preparing the oxidized propylene polymer material, propylene polymer starting material is first exposed to ionizing radiation under a blanket of inert gas, preferably nitrogen. The ionizing radiation should have sufficient energy to penetrate the mass of polymer material being irradiated to the extent desired. The ionizing radiation can be of any kind, but preferably includes electrons and gamma rays. More preferred are electrons beamed from an electron generator having an accelerating potential of about 500 to about 4,000 kilo volts. Satisfactory results are obtained at a dose of ionizing radiation of about 0.1 to about 15 megarads ("Mrad"), preferably about 0.5 to about 9.0 Mrad. The term "rad" is usually defined as that quantity of ionizing radiation that results in the absorption of 100 ergs of energy per gram of irradiated material regardless of the source of the radiation using the process described in U.S. Pat. No. 5,047,446. Energy absorption from ionizing radiation is measured by the well-known convention dosimeter, a measuring device in which a strip of polymer film containing a radiation-sensitive dye is the energy absorption sensing means. Therefore, as used in this specification, the term "rad" means that quantity of ionizing radiation resulting in the absorption of the equivalent of 100 ergs of energy per gram of the polymer film of a dosimeter placed at the surface of the propylene polymer material being irradiated, whether in the form of a bed or layer of particles, or a film, or a sheet. The irradiated propylene polymer material is then oxidized, preferably in a series of steps. According to a preferred embodiment, the first treatment step comprises heating the irradiated polymer in the presence of a first controlled amount of active oxygen greater than about 0.004% by volume but less than about 15% by volume, preferably less than about 8% by volume, more preferably less than about 5% by volume, and most preferably from about 1.3% to about 3.0% by volume, to a first temperature of at least about 10°C but below the softening point of the polymer, preferably about 20°C to about 140°C, more preferably about 25°C to about 100°C, and most preferably about 40°C to about 80°C. Heating to the desired temperature is accomplished as quickly as possible, preferably in less than about 10 minutes. The polymer is then held at the selected temperature, typically for about 5 to about 90 minutes, to increase the extent of reaction of the oxygen with the free radicals in the polymer. The holding time, which can be determined by one skilled in the art, depends upon the properties of the starting material, the active oxygen concentration used, the irradiation dose, and the temperature. The maximum time is determined by the physical constraints of the fluid bed. In the second treatment step, the irradiated polymer is heated in the presence of a second controlled amount of oxygen greater than about 0.004% but less than about 15% by volume, preferably less than about 8% by volume, more preferably less than about 5% by volume, and most preferably from about 1.3% to about 3.0% by volume, to a second temperature of at least about 25°C but below the softening point of the polymer. Preferably, the second temperature is from about 100°C to less than the softening point of the polymer, and greater than the first temperature of the first step. The polymer is then held at the selected temperature and oxygen concentration conditions, for about 10 to about 300 minutes, preferably about 20 to about 180 minutes, to increase the rate of chain scission and to minimize the recombination of chain fragments so as to form long chain branches, i.e., to minimize the formation of long chain branches. The holding time is determined by the same factors discussed in relation to the first treatment step. In the optional third step, the oxidized propylene polymer material is heated under a blanket of inert gas, preferably nitrogen, to a third temperature of at least about 80°C but below the softening point of the polymer, and held at that temperature for about 10 to about 120 minutes, preferably about 60 minutes. A more stable product is produced if this step is carried out. It is preferred to use this step if the oxidized olefin polymer is going to be stored rather than used immediately. The polymer may then be cooled to a fourth temperature of about 70°C over a period of about 5-30 minutes under a blanket of inert gas, preferably nitrogen, before being discharged from the bed. In this manner, stable intermediates are formed that can be stored at room temperature for long periods of time without further degradation. A preferred method of carrying out the treatment is to pass the irradiated propylene polymer through a fluid bed assembly operating at a first temperature in the presence of a first controlled amount of oxygen, passing the polymer through a second fluid bed assembly operating at a second temperature in the presence of a second controlled amount of oxygen, and then maintaining the polymer at a third temperature under a blanket of nitrogen, in a third fluid bed assembly. In commercial operation, a continuous process using separate fluid beds for the first two steps, and a purged, mixed bed for the third step is prefened. However, the process can also be carried out in a batch mode in one fluid bed, using a fluidizing gas stream heated to the desired temperature for each treatment step. Unlike some techniques, such as melt extrusion methods, the fiuidized bed method does not require the conversion of the irradiated polymer into the molten state and subsequent re-solidification and comminution into the desired form. The fluidizing medium can be, for example, nitrogen or any other gas that is inert with respect to the free radicals present, e.g., argon, krypton, and helium. The concentration of peroxide groups formed on the polymer can be controlled by varying the radiation dose during the preparation of the irradiated polymer and the amount of oxygen to which such polymer is exposed after irradiation. The oxygen level in the fluid bed gas stream is controlled by the addition of dried, filtered air at the inlet to the fluid bed. Air must be constantly added to compensate for the oxygen consumed by the formation of peroxides in the polymer. Alternatively, the propylene polymeric peroxide material can be prepared according to the following procedures, h a first treatment step, the propylene polymer starting material is treated with 0.1 to 10 wt% of an organic peroxide initiator while adding a controlled amount of oxygen so that the propylene polymer material is exposed to greater than 0.004% but less than 21 ) by volume, preferably less than 15%, more preferably less than 8% by volume, and most preferably 1.0% to 5.0% by volume of oxygen; at a temperature of at least 20°C but below the softening point of the polymer, preferably about 25°C to about 140°C. hi the second treatment step, the polymer is then heated to a temperature of at least 25°C up to the softening point of the polymer, preferably from 100°C to less than the softening point of the polymer, at an oxygen concentration that is within the same range as in the first treatment step. The total reaction time is typically about 0.5 hour to four hours. After the oxygen treatment, the polymer is treated at a temperature of at least 80°C but below the softening point of the polymer, typically for 0.5 hour to about two hours, in an inert atmosphere such as nitrogen to quench any active free radicals. Suitable organic peroxides include acyl peroxides, such as benzoyl and dibenzoyl peroxides; dialkyl and aralkyl peroxides, such as di-tert-butyl peroxide, dicumyl peroxide; cumyl butyl peroxide; l,l,-di-tert-butylperoxy-3,5,5-trimethylcyclohexane; 2,5-dimethyl- l,2,5-tri-tert-butylperoxyhexane,and bis(alpha-tert-butylperoxy isopropylbenzene), and peroxy esters such as bis(alpha-tert-butylperoxy pivalate; tert-butylperbenzoate; 2,5- dimethylhexyl-2,5-di(perbenzoate); tert-butyl-di(perphthalate); tert-butylperoxy-2- ethylhexanoate, and l,l-dimethyl-3-hydroxybutylperoxy-2-ethyl hexanoate, and peroxycarbonates such as di(2-ethylhexyl) peroxy dicarbonate, di(n-propyl)peroxy dicarbonate, and di(4-tert-butylcyclohexyl)peroxy dicarbonate. The peroxides can be used neat or in diluent medium. The oxidized propylene polymer material used in the invention preferably contains about 1 mmol to about 200 mmol total peroxide per kilogram of polymer material. More preferably, the oxidized propylene polymer material contains from about 5 mmol to about 150 mmol total peroxide per kilogram of polymer material, most preferably from about 10 to about 100 mmol total peroxide per kilogram of oxidized propylene polymer material. Without wishing to be bound by theory, the oxidized propylene polymer material used in the invention contains peroxide linkages that can form free radicals which then react with oxygen molecules and remove them from the surrounding gas mixture. The oxidized propylene polymer oxygen scavengers used in the invention can be in the foπn of melt processed articles such as films, sheets, or molded articles. Alternately, the oxidized propylene polymer material can be produced in a particulate form including, for example, spheres, powders, flakes or granules. When produced in particulate form, the oxidized propylene polymer material preferably is not further melt processed, since melt processing may induce degradation of the peroxide linkages that react with oxygen, thereby reducing the oxygen absorbing capability of the oxidized propylene polymer material. When the oxidized propylene polymer material is used as spheres, the spheres preferably have a diameter of about 0.01 to about 5 mm, more preferably about 0.5 mm to about 3 mm. Preferably, the spheres have a porosity from about 0.1 ml/g to about 0.6 ml/g. When used as a powder, the powder preferably has a particle size distribution of about 0.01 mm to about 0.5 mm. When used as granules, the granules have a typical size of about 0.01 mm to about 5 mm, preferably about 0.5 mm to about 3 mm. Preferably, the powder, flakes or granules have a porosity of from about 0.1 ml/g to about 0.6 ml/g. Typically, the oxidized propylene polymer material absorbs oxygen at levels above about 0.1 ml oxygen per gram of the oxidized propylene polymer material. According to the method of the invention for absorbing oxygen from a gas mixture within an enclosure, the gas mixture is exposed to an effective amount of an oxidized propylene polymer material having a peroxide concentration of about 1 to about 200 mmol total peroxide per kilogram of oxidized propylene polymer material. Preferably, the oxidized propylene polymer material has a peroxide concentration of about 5 to about 150 mmol total peroxide per kilogram of oxidized propylene polymer material, more preferably a peroxide concentration of about 10 to about 100 mmol total peroxide per kilogram of oxidized propylene polymer material. As used in this specification, an effective amount of the oxidized propylene polymer material is that quantity of material required to absorb at least 0.1% by volume of the original oxygen concentration present in the gas mixture. When used to absorb oxygen in the gas mixture of an enclosure, the temperature of the polymeric peroxide is typically maintained below its melting point, preferably at a temperature of about 20°C to 140°C, more preferably at a temperature from about 60°C to about 120°C, most preferably at a temperature from about 100°C to about 110°C. Preferably, the starting material for making the oxidized propylene polymer material is a propylene homopolymer having an isotactic index greater than about 80%. The oxidized propylene polymer material is preferably prepared by irradiation followed by exposure to oxygen as described herein above. The enclosures of the invention can be any article, the structure of which encloses a gas mixture having an oxygen concentration. The enclosure can be manufactured from any material that provides a substantial barrier to the free-flow of oxygen, including for example, plastic, glass, metals, rubber, wood, cardboard, particle board, stone or combinations thereof. The enclosure can have a rigid or semi-rigid shape, including for example, boxes, containers, bottles, drums, cans; or non-rigid shapes, including for example, bags, folded films or sheets, or shrink-wrapped systems. The enclosure can be of any size and can include rooms, cabinets or equipment such as pipes and piping systems, ducts and ductwork, conduit and conduit systems, or vessels. The gas mixture contacted with the oxidized propylene polymer material can have any composition consistent with the materials of construction of the enclosures used. Typically, the gas mixture contained within the enclosure will be a mixture of nitrogen and oxygen, although small amounts of other components can be present. Most typically, the gas mixture will be air having an oxygen content of about 20.9% by volume. The oxidized propylene polymer materials used in the invention typically will be used to reduce the oxygen content of the gas mixture in an enclosure from a first higher oxygen level to a second lower oxygen level. The enclosure may from time to time be opened to an environment having a higher oxygen concentration, thereby temporarily increasing the oxygen concentration in the enclosure. The first higher oxygen level and second lower oxygen level can be any oxygen percentage. Alternately, the oxidized propylene polymer material can be used to maintain an oxygen level, where oxygen is introduced into the enclosure through leakage into the enclosure from an outside atmosphere containing higher levels of oxygen. The leakage can occur through seams of the enclosure or due to oxygen permeability of the walls of the article. Further, leakage can result from deliberately introducing oxygen into the enclosure to maintain a constant oxygen level. Finally, the process of the invention can be used in conjunction with conventional systems that maintain an inert blanket of gas, such as nitrogen, within an enclosure. The gas mixture of the enclosure may be exposed to the oxidized propylene polymer material in any manner. For example, the material may be placed directly inside the enclosure, or the material may be included in the materials of construction of the enclosure. The material may also first be deposited in a separate container and then being placed inside the enclosure. The configuration of the container can be of any type consistent with the enclosure into which it is placed. The container itself may be permeable to oxygen, or may be modified so as to allow contact of the gas mixture and the oxidized propylene polymer material. Alternately, the oxidized propylene polymer material used for absorbing oxygen in the methods of the invention can be in the form of a melt processed propylene polymer, such as a film, sheet or molded article that has been oxidized according to the procedures described above. For example, a method for absorbing oxygen from a gas mixture within an enclosure with an oxidized propylene polymer film, sheet or molded article would comprise first forming an oxidized propylene polymer film, sheet or molded article by preparing a propylene polymer film, sheet or molded article, and then oxidizing the propylene polymer film, sheet or molded article by the methods described above. The oxidized propylene film sheet or molded article, having a peroxide concentration of about 1 to about 200 mmol total peroxide per kilogram of the oxidized propylene polymer film, sheet or molded article, preferably about 5 to about 150 mmol total peroxide per kilogram of the oxidized propylene polymer film, sheet or molded article, more preferably about 10 to about 100 mmol total peroxide per kilogram of the oxidized propylene polymer film, sheet or molded article, may then be exposed to a gas mixture having an oxygen content, wherein oxygen is absorbed by the oxidized propylene polymer film, sheet or molded article. In the following examples, melt flow rate ("MFR") was determined by ASTM D1238 at 230°C at 2.16 kg, and are reported in units of dg/min. Isotactic Index ("I.I.") is defined as the percent of propylene polymer insoluble in xylene. The weight percent of propylene polymer soluble in xylene at room temperature is determined by dissolving 2.5 g of polymer in 250 ml of xylene at room temperature in a vessel equipped with a stirrer, and heating at 135°C with agitation for 20 minutes. The solution is cooled to 25°C while continuing the agitation, and then left to stand without agitation for 30 minutes so that the solids can settle. The solids are filtered with filter paper, the remaining solution is evaporated by treating it with a nitrogen stream, and the solid residue is vacuum dried at 80°C until a constant weight is reached. These values coreespond substantially to the isotactic index determined by extracting with boiling n-heptane, which by definition constitutes the isotactic index of polypropylene. The peroxide content of the propylene polymeric peroxides is measured as described in Quantitative Organic Analysis via Functional Groups, by S. Siggia et al., 4^th Ed., NY, Wiley 1979, pp. 334-42. The porosity of the polymers was measured as described in Winslow, N. M. and Shapiro, J. J., "An Instrument for the Measurement of Pore-Size Distribution by Mercury Penetration," ASTM Bull., TP 49, 39-44 (Feb. 1959), and Rootare, H. M., "A Review of Mercury Porosimetry," 225-252 (In Hirshhom, J. S. and Roll, K. H., Eds., Advanced Experimental Techniques in Powder Metallurgy, Plenum Press, New York, 1970). Oxygen concentrations were determined using a model 901 Quanteck Oxygen Analyzer, commercially available from Cole-Parmer. Unless otherwise specified, all references to parts, percentages and ratios in this specification refer to percentages by weight. Preparation 1 A propylene homopolymer having a MFR of 9.4 dg/min, LI. of 96.5%, and porosity of 0.51 ml/g, commercially available from Basell USA Inc. was irradiated at 4.0 Mrad under a blanket of nitrogen. The homopolymer was in the form of spheres having diameters of between about 0.1 mm to about 3 mm. The irradiated polymer was then treated with air (20.9% by volume of oxygen) at room temperature for one hour before it was sealed in an air tight aluminum bag. The MFR of the resultant polymer material was 3073 dg/min. Preparation 2 A propylene homopolymer having a MFR of 9.4 dg/min, LI. of 96.5%, and porosity of 0.51 ml/g, commercially available from Basell USA Inc. was irradiated at 0.5 Mrad under a blanket of nitrogen at room temperature. The homopolymer was in the form of spheres having diameters of between about 0.1 mm to about 3 mm. The irradiated polymer was then treated with 1.45% by volume of oxygen at 140°C for 60 minutes. The oxygen was then removed. The polymer was then heated at 140°C under a blanket of nitrogen for 60 minutes, cooled and collected. The MFR of the resultant polymer material was 325 dg/min. The peroxide concentration was 12.3 mmol total peroxide per kilogram of oxidized polymer. Preparation 3 A propylene homopolymer (1000 g) having a MFR of 9.4 dg/min, I.I. of 96.5%, and porosity of 0.51 ml/g, commercially available from Basell USA Inc was added to a 7.6 liter autoclave reactor. The homopolymer was in the form of spheres having diameters of between about 0.1 mm to about 3 mm. An organic peroxide (lOOg), Lupersol PMS, which is a 50 wt% solution of t-butyl peroxy-2-ethylhexanoate in odorless mineral spirits (OMS), obtained from Atofina North America, Inc. was pumped into the reactor at a feed rate of 6.5 ml/min. The homopolymer was then heated to 100°C and exposed to a gas mixture containing 0.8% by volume of oxygen in nitrogen. The reaction was held at 100°C for 60 minutes and the homopolymer was heated to 140°C and held for 60 minutes at the same temperature. The homopolymer was then cooled to room temperature and collected in an air-tight aluminum bag. The MFR of the resultant polymer materials was 2412 dg/min. In Tables I-N, the oxygen absorption properties of the above preparations were evaluated by using 5 grams of the polymer in a sealed 500 ml glass bottle containing air. The polymer/bottle were placed in a temperature controlled convection oven. The oxygen absorption of the oxidized propylene polymer materials obtained in preparations 1-3 were measured over time at various temperatures. Table I illustrates oxygen absorption of the oxidized propylene polymer material as a function of time at 20°C.

Table II illustrates oxygen absorption of the oxidized propylene polymer material as a function of time at 40°C

Table III illustrates oxygen absoφtion of the oxidized propylene polymer material as a function of time at 60°C.

Table IN illustrates oxygen absorption of the oxidized propylene polymer material as a function of time at 80°C.

Table N illustrates oxygen absorption of the oxidized propylene polymer material as a function of time at 100°C

Tables I-N illustrate that the absorption of oxygen increases with temperature for all the oxidized propylene polymer material samples, with the oxidized propylene polymer material produced by irradiation without the final heating step under a blanket of inert gas (preparation 1) demonstrating higher oxygen scavenging performance than either the oxidized propylene polymer material produced using an organic peroxide (preparation 3), or the sample produced via nradiation but including a final heating step (preparation 2). hi Table NI, the oxygen concentration of the glass bottle at 100°C as a function of time is illustrated.

Table VI

Other features, advantages and embodiments of the invention disclosed herein will be readily apparent to those exercising ordinary skill after reading the foregoing disclosures, h this regard, while specific embodiments of the invention have been described in considerable detail, variations and modifications of these embodiments can be effected without departing from the spirit and scope of the invention as described and claimed.

Claims

1. A method for absorbing oxygen from a gas mixture within an enclosure, the gas mixture having an oxygen content, the method comprising exposing the gas mixture to an oxidized propylene polymer material having a peroxide concentration of about 1 to about 200 mmol total peroxide per kilogram of oxidized propylene polymer material, wherein oxygen is absorbed by the oxidized propylene polymer material.

2. The method of claim 1 wherein the oxidized propylene polymer material is in a particulate form.

3. The method of claim 2 wherein the particulate form is chosen from spheres, powder, flakes and granules.

4. The method of claim 3 wherein the particulate form is a sphere.

5. The method of claim 4 wherein the sphere has a diameter of about 0.5 mm to about 3 mm and a porosity of about 0.1 ml/g to about 0.6 ml/g.

6. The method of claim 1 wherein the oxidized propylene polymer material is obtained from a propylene polymer chosen from: (A) a homopolymer of propylene having an isotactic index greater than about 80%; (B) a random copolymer of propylene and an olefin chosen from ethylene and C₄-C₁₀ c-olefins, containing about 1 to about 30 wt% of the olefin, and having an isotactic index greater than about 60%; (C) a random terpolymer of propylene and two olefins chosen from ethylene and C₄-C₈ α-olefins, containing about 1 to about 30 wt% of the olefins, and having an isotactic index greater than about 60%; (D) an olefin polymer composition comprising: (i) about 10 parts to about 60 parts by weight of a propylene homopolymer having an isotactic index at least about 80%, or a crystalline copolymer chosen from (a) propylene and ethylene, (b) propylene, ethylene and a C₄-C₈ α-olefin, and (c) propylene and a C₄-C₈ α-olefin, the copolymer having a propylene content of more than about 85% by weight, and an isotactic index greater than about 60%; (ii) about 3 parts to about 25 parts by weight of a copolymer of ethylene and propylene or a C₄-C₈ α-olefin that is insoluble in xylene at ambient temperature; and (iii) about 10 parts to about 85 parts by weight of an elastomeric copolymer selected from the group chosen from (a) ethylene and propylene, (b) ethylene, propylene, and a C₄-C₈ α-olefin, and (c) ethylene and a C₄-C₈ α-olefin, the copolymer optionally containing about 0.5% to about 10% by weight of a diene, and containing less than about 70% by weight of ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity of about 1.5 to about 6.0 dl/g; the total of (ii) and (iii), based on the total olefin polymer composition being from about 50% to about 90% by weight, and the weight ratio of (ii)/(iii) being less than about 0.4; and (E) mixtures thereof.

7. The method of claim 6 wherein the propylene polymer is a homopolymer having an isotactic index greater than about 80%.

8. The method of claim 1 wherein the oxidized propylene polymer material is produced by an rrradiation process followed by oxidation.

9. The process of claim 1 wherein the oxidized propylene polymer material is at a temperature of about 20°C to about 140°C.

10. A method comprising: (i) preparing a propylene polymer film, sheet or molded article; and (ii) oxidizing the propylene polymer film, sheet or molded article, thereby forming an oxidized film, sheet or molded article having a peroxide content of about 1 to about 200 mmol total peroxide per kilogram of the oxidized film sheet or molded article.

11. A method for absorbing oxygen from a gas mixture within an enclosure, the method comprising exposing the gas mixture having an oxygen content to an oxidized propylene polymer film, sheet or molded article having a peroxide concentration of about 1 to about 200 mmol total peroxide per kilogram of the oxidized propylene polymer film or sheet, wherein oxygen is absorbed by the oxidized propylene polymer film, sheet or molded article.