DE2163633A1 - Graft copolymers and methods of making the same - Google Patents

Description

Patent Attorney nS-BB ^ E I-Sn ₃ . K. LAMP; Dr -Ing. R. D ι- Ε 1 Z jr.
β M Ο η ch β η 22, Steinsdorfstr. IO 2163833

046-18.Ο43Ρ December 21, 1971

AGENCE NATIONALE DE VALORIZATION DE LA RECHERCHE "ANVAR" Paris (France)

Graft copolymers and methods of making them

the same

The invention relates to graft copolymers and their manufacture.

The invention specifically relates to polymers with grafted-on alternating copolymers, with alternating copolymers being understood as meaning those copolymers composed of at least two monomers, the molecules of which regularly alternate by at least 50%.

It is known that alternating copolymers of high molecular weight, starting from certain monomer pairs or -Combinations (couples) can be obtained in the presence of metal salts, which lead to complex formation with the polar monomers are capable. The polymerization can then take place in the presence of the complexing agent alone or in the presence of the complexing agent and a radical initiator or radical generator take place. In the latter case, the equimolar and alternating remains Composition of the copolymer obtained, but the rate of polymerization is increased.

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It is also known that one can use polar vinyl monomers can graft onto an elastomer substrate by doing the Substrate with which by a metal halide or an organometallic derivative, in particular an organoaluminum compound, polar monomers converted into a complex in an inert one Brings solvent and in the presence of a free radical generating substance.

According to the invention are now alternating by a new application of complexing agents for the polar monomers Copolymers of at least one polar vinylic monomer and one vinyl aromatic monomer, and in particular alternating Copolymers of acrylonitrile-styrene and methyl methacrylate-styrene grafted onto elastomers, creating novel products with interesting properties.

The graft copolymers thus obtained according to the invention have improved heat resistance. For example, when grafting on, alternating acrylonitrile-styrene copolymers are obtained on polybutadiene special acrylonitrile. Butadiene-styrene graft copolymers with compared to the conventional acrylonitrile / butadiene / styrene copolymers. noticeably improved properties.

The inventive method for grafting alternating copolymers of at least one polar vinylic monomer and a vinyl aromatic monomer or their substituted homologues or derivatives on elastomers is characterized in that at least one elastomer with the (derived or substituted) polar vinylic monomer and the (derived or substituted)

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vinyl aromatic monomers brought together in the presence of at least one metal derivative, the complex formation with the (derived or substituted) polar vinylic monomers is capable.

According to a preferred embodiment of the invention Procedure is additional during the grafting reaction at least one free radical initiator in the reaction mixture present.

In the following, for the sake of simplicity, both the monomer itself and its various derivatives and substituted compounds are referred to as "monomers".

The elastomers on which the alternating copolymers Any saturated or unsaturated polymers or copolymers of an elastomeric nature can be grafted on be. So you can get various polymers and copolymers of diolefins as well as various copolymers of olefins or olefins and polyenes. Find among the most common elastomers the various types of polybutadiene; for example by emulsion copolymerization of butadiene with an acid carboxylated polybutadiene obtained of the acrylic type, particularly methacrylic acid; Polyisoprene; Butyl rubber; Polyisobutene; Copolymers of ethylene and propylene; and terpolymers of ethylene, propylene and diene, the diene being especially due to dicyclopentadienes 5-ethylidene-norbornene- (£) or hexadiene (1, ^) is formed. It is also possible to use mixtures or combinations of such elastomers.

Of the monomers used to form the alternating copolymer, at least one is selected from the group of

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selected polar vinylic monomers, the polar group in particular by a nitrile, carboxylic acid, ester or Ketone grouping is formed and! At least one other from the group of vinyl aromatic monomers »

Although the examples described below refer to copolymers having alternating motifs or units of a polar vinyl monomer and a vinyl aromatic monomer, it is clear that one Without departing from the scope of the invention, other alternating copolymers can also be provided which fall within the scope of the above Definition fall and at least partially have different motifs or units than those of the said monomers.

Among the polar vinylic monomers are the acrylic ones Mention esters and in particular alkyl acrylates and methacrylates such as ethyl, methyl and butyl acrylate, methyl methacrylate, Butyl methacrylate, acrylic and methacrylic acids and vinyl ketones, with acrylonitrile and methyl methacrylate according to the invention are preferred as monomers.

The vinyl aromatic monomers include, in particular, styrene and p-chlorostyrene, 06-methylstyrene and oC -butylstyrene.

The complex formation of the polar monomer with a metal complexing agent or a complexing metal compound is necessary to achieve the special graft copolymers essential according to the invention. In the context of the invention Numerous metal sequestrants can be used in the process. The halides of are particularly suitable

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Zinc, cadmium, magnesium, tin and aluminum as well as certain organometallic compounds such as halogenated or non-halogenated Alkyl aluminum compounds. According to a preferred embodiment of the invention, chlorides are the above highlighted metals and especially zinc chloride are used.

The proportion of the complexing agent can vary within wide limits, generally between 0.005 and 10 mol can be used per mole of polar monomer. The proportion of the complexing agent is preferably between 0.05 and 1 mol per mole of polar monomer.

According to a preferred feature of the invention, in addition to the complexing agent, there is a free radical initiator in the reaction medium present, whereby the rate of polymerization can be increased. ,,,.

The radical initiators used are in particular nitrogen derivatives and organic peroxides, such as acyl peroxides, Ketone peroxides, aldehyde peroxides and hydroperoxides, although other compounds can also be used which enable are free under the conditions of the grafting reaction Let radicals arise.

Among the preferred peroxides are benzoyl peroxide, lauroyl peroxide, acetyl peroxide, diisopropylbenzene hydroperoxide and tert-butyl hydroperoxide to be mentioned.

The proportion of the radical initiator can be between 0.0001 and 0.05 moles per mole of total monomer used, and preferably between 0.0005 and 0.01. Mole (per

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Moles of monomer).

Although the alternating copolymers forming the grafts, regardless of the relative proportions of (polar vinylic and vinyl aromatic) monomers can be obtained in the alternating form, is preferred Use exactly equimolar amounts of the monomers.

To carry out the grafting reaction, that which has been dissolved or dispersed in an inert liquid is brought Elastomers with the selected polar vinylic and vinylaromatic monomers and the complexing agent and gfs. the radical initiator together and holds the entire mixture for a sufficient time to achieve a graft copolymer at the selected temperature.

An inert liquid is understood to mean a liquid that participates in the reaction with the different involved products does not respond. Particularly suitable are aliphatic ^ hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene and toluene, or cycloaliphatic hydrocarbons such as cyclohexane Mixtures of these substances.

It can also be done without a solvent or dispersant work by dissolving or dispersing the elastomer in the non-polar monomer.

Otherwise, the polymerization can be carried out according to that described Process can be carried out in a first stage without solvents, after which the after a certain time

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permanently obtained reaction mixture is dispersed in water. For this procedure it can be assumed that the copolymers and grafts formed in the first stage have an alternating effect Structure, while those formed after suspending or emulsifying have a random structure own.

This technique can have the advantage that the complexing agent is automatically removed during suspension in water the polymer mass is separated.

The grafting reaction is generally carried out at temperatures ranging from 0 to 200 ^° C .; these temperatures are in particular between 0 and 150 ° C. and preferably between 20 and 100 ^° C.

The complexing agent can be separated into the reaction medium be introduced, however, the addition is in the form of a solution in the polar monomer.

The radical initiator can also be added to the reaction mixture separately or in the form of a reading in the vinyl aromatic monomer.

When looking at the molecular weight of the grafts of alternating copolymers and the gel fraction of the graft copolymers If you want to exert influence, the grafting reaction is carried out in the presence of chain transfer agents, in particular long-chain mercaptans and preferably tert-dodecyl mercaptan. This allows one to adjust and control the reaction and the properties of the

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received products.

The grafting reaction is generally carried out in an inert atmosphere, for example under nitrogen, for its duration Depending on the products to be manufactured, it can range from a few 10 Minutes to several hours vary.

At the end of the reaction, the reaction mixture is processed by any method by which the graft copolymer can be separated or isolated.

For a better understanding of the technical features and advantages of the invention, exemplary embodiments are given below described, but of course neither the way of implementation nor the possible applications should restrict.

example 1

A series of k experiments (A, B, C and D) for grafting alternating copolymers of acrylonitrile-styrene onto carboxylated polybutadiene obtained by emulsion copolymerization of butadiene and methacrylic acid with a molecular weight of 15,000 and a carboxyl group content of 0.7-0.8. 10 ■ carried out per gram of polymer.

For each experiment 100 ml of a benzene
Solution with 5.15 g of the above carboxylated polybutadiene was added to the reaction vessel and the previous one

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added monomers purified by vacuum distillation over calcium hydride, namely 0.3 mol of acrylonitrile and 0.3 moles of styrene.

In experiment A, which functions as a comparative experiment, only a radical initiator was used, namely benzoyl peroxide, used in an amount of 0.2 g, which was introduced into the reaction vessel in the form of a solution in the styrene monomer became.

In experiments B and C, grafting was used alone carried out in the presence of 0.03 mol of zinc chloride, the was introduced into the reaction vessel in the form of a solution in acrylonitrile.

In experiment D, the grafting reaction was carried out in the presence of 0.03 mol of zinc chloride and 0.2 g of benzoyl peroxide, the zinc chloride being dissolved in the acrylonitrile and the peroxide being dissolved in the styrene being added to the reaction vessel.

After purging with nitrogen, the reaction vessel was tightly closed and then placed in a 60 ° ( brought thermdstatisiert bath and stirred the mixture.

The duration of the grafting reaction in the experiments was A, B and C 16 hours and in experiment D 2.3 hours.

At the end of the reaction in experiment A, a very viscous solution was obtained from which all of the polymers were precipitated. The obtained polymer mixture was dissolved in benzene containing 5 to 10 % methanol and then for separation

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the remaining monomers precipitated in methanol. The reprecipitated ones Polymers were redissolved and the pure grafted became from the ungrafted acrylonitrile-styrene copolymer by forming an ionic gel by neutralizing the carboxyl groups of the grafted separated with sodium methoxide.

In experiments B, C and D, the product obtained at the end of the reaction was a white gel. This gel was used for extraction of the unchanged or non-grafted polybutadiene treated with chloroform. Thereafter, the acrylonitrile-styrene copolymer separated by solution in a mixture of benzene and dimethylformamide. The one remaining after these extractions The rest was the pure graft copolymer.

The results obtained in these experiments are summarized in the table below.

Table I.

Ver Rk.- ZnCIg Benzoyl -Total- Aufpfro Plug Mole £ gel search duration (Mole) peroxide Monomer care yield ¹ acrylic % - - (Hours.) (G) umwand- Degree (b) nitrile lung (a) in the (By weight) acrylic nitrile Styrene Copoly- meren 0 (c) A. 16 0.03 0.2 49 1.06 0.25 36 0 B. 16 0.03 0 79 4.17 0.72 50 76 C. 2.3 0.03 0 36 2.59 0.82 49.2 78 D. 16 0.2 88 6.20 0.78 49 80

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(a) The degree of grafting is the weight ratio between the grafted aeryl nitrile-styrene copolymer and the starting elastomer.

(b) The graft yield is the ratio between

the weight of the grafted aeryl nitrile-styrene copolymer and the total weight of the monomers polymerized.

(c) The percentage is determined via the acrylonitrile content in the graft copolymer (determined by determining the nitrogen f content according to Kjeldahl) and the grafted acrylonitrile-styrene copolymer portion (determined by determining the double bonds of the polybutadiene according to the degradation method ' with osmic acid and tert-butyl hydroperoxide). \

A comparison of the results of experiments B, C and D with those of experiment A shows that the presence of zinc chloride or zinc chloride and benzoyl peroxide results in a significant increase in the degree of grafting and the graft yield. In addition, the presence of zinc chloride alone leads to grafts, more than 50 % of which consist of alternating copolymers with equimolar proportions of styrene and acrylonitrile. In the absence of zinc chloride, grafts are found which are formed by random acrylonitrile-styrene copolymers.

Example 2

Repeating the procedure of Example 1, Experiment C, 2 grafting experiments (E and P) were carried out,

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in which, in addition to the reaction medium, different amounts of a chain transfer agent, namely tert-dodecyl mercaptan (abbreviated with tpM) was added and the duration of the grafting reaction was reduced to 2 hours.

The results obtained are shown in Table II.

Table II

Ver
search Rk.-
duration
(Hours.) ZnCl ₂
(Mole) tDM
(ml) Total-
Monomer
convertible
(Weight #) Graft
• care
Degree Graft
the end-,
prey • mole #
acrylic
nitrile
in al
ternia
end
Copoly-
meren gel
% C. 2.3 0.03 0 36 2.59 0.82 49.2 78 E. 2 0.03 0.2 15.9 0.95 0.62 50.2 77 P. 2 0.03 0.5 13.8 0.72 0.40 49.3 66

Examination of the values in Table II shows that the alternating composition of the carboxylated polybutadiene Grafted acrylonitrile-styrene copolymers is retained if you carry out the grafting reaction in the presence of a Chain transfer agent performs and that the application

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increasing proportions of chain transfer agent allows a lowering of the gel content of the graft copolymer.

In contrast, the overall conversion of styrene and acrylonitrile as well as the degree of grafting and the grafting yield are reduced.

Example 3

In a reaction vessel to be analogous to that of the preceding tests, a series of grafts (G, H, I) carried out by respectively different elastomer substrates, namely butyl rubber, polyisobutene, and a terpolymer of A ^- Thylen / propylene 1 en / diene type used became.

In each case 100 ml of a solution were put into the reaction vessel of the elastomer in cyclohexane and 0.5 mol of acrylonitrile with zinc chloride (0.03 mol) and 0.3 mol of styrene dissolved therein added.

After purging with nitrogen, the reaction vessel was tightly closed and then ^{kept at 63 °} C. for 18 hours with stirring. After this time a white deposit had formed on the walls of the reaction vessel.

The polymers contained in the reaction mixture were used to separate the remaining monomers with methanol precipitated, after which the polymer mixture obtained to separate the non-grafted alternating acrylonitrile-styrene copolymer leaving the pure graft copolymer

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Treated with acetone for 24 hours.

The results obtained in these experiments are summarized in Table III below.

Table III

attempt Elastomer Elastomerge
weight (g) Total-
Monomer
convert.
(Weight #) on
grafting
Degree Plug
the end
prey G Butyl chew
schuk - 5.10 53 0.82 0.40 H Polyiso
butylene 5 14.9 0.47 . 0.50 I. Terpoly
mer 5.25 19.1 0.22 0.40

The grafting is also positive for the elastomers listed in Table III, and it is found that more than 50 % of the grafting is formed by alternating acrylonitrile-styrene copolymers.

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~ 15 -

It should be noted that the grafting is all the better The more remaining double bonds the elastomer used as substrate (see butyl rubber) has.

Example 4

In a reaction vessel analogous to that of Example 1, a series of grafting experiments (J, K, L, M) carried out with different elastomer substrates.

For each of the substrates used, a graft reaction was carried out under conditions analogous to Experiment A and a further graft reaction under the conditions analogous to Experiment D (Example I), but with replacement of the benzene by cyelohexane, reducing the reaction time to 5 hours and maintaining one Temperature of 6-1 ⁰ C during the grafting.

The results obtained are summarized in Table IV. '..'; '

Table IV

attempt Elastomer Plug
conditions
after attempt peroxide
(ß) ZnCl ₂
(Mole) on
pfro
care
Degree Plug
the end
prey J Terpolymer
EP DM D. 0.2 0.05 0.06 0.42 K Butyl
rubber A. 0.2 0 0.005 0.11 D. 0.2 0.03 0.05 0.28 ^ A. 0.2 O 0.005 0.10

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Ports. Tab. IV

L. Polyiso
butylene D. 0.2 0.03 0.20 0.38 M. Polybuta
serve A. 0.2 0 0.05 0.15 (cis-1,4) D. 0.2 0.03 0.13 0.50 A. 0.2 0 0.05 0.21

It has been found that the grafts obtained in the presence of zinc chloride are made by alternating copolymers formed by acrylonitrile and styrene, while the grafts formed in the absence of zinc chloride are statistical Are acrylonitrile-styrene copolymers.

It was also found that the presence of zinc chloride significantly increases the degree of grafting is made possible.

Example 5

5 g of butyl rubber dissolved in 0.3 mol of styrene and subsequently 0.3 mol of acrylonitrile with anhydrous zinc chloride (0.03 mol) dissolved therein were placed in a reaction vessel analogous to that of Example 1. After nitrogen had been passed through, the reaction vessel was then tightly closed and kept at 60 ^° C. for 5.25 hours.

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After this time, an overall thickening was observed. The graft copolymer was derived from the acrylonitrile / styrene copolymer by extraction of the latter with acetone (3 days long) separated.

The overall conversion of acrylonitrile and styrene makes 72 wt -.% Of the introduced monomers from.

The graft yield is 0.1J and the degree of grafting 0.25; the grafts are made by an alternating one Copolymer formed by acrylonitrile and styrene.

It can therefore be assumed that the grafting of the alternating copolymers of acrylonitrile and styrene on the elastomer also takes place in the block or in bulk. However, the rate of formation is for the ungrafted alternating copolymers higher and the graft yield lower than 0.5.

Example 6

In a reaction vessel analogous to that of example 1 a first stage of the grafting reaction was carried out in bulk up to a certain degree of conversion, whereupon a polymerization in suspension followed.

5.1 g of polybutadiene were dissolved in the reaction vessel in 0.7 mol of styrene with 0.5 g of benzoyl peroxide) and then 0.4-7 mol of acrylonitrile with anhydrous zinc chloride dissolved therein (O, O4; 5 mol) added.

After one hour of polymerization at 60 C accordingly a degree of conversion above the inversion of the phases was the

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Reaction mass in 500 ml of water with 30 g of NaCli 0.3 g of Natriurathiosulfatj 6 ml of a 6% polyvinyl alcohol solution and 1 g of benzoyl peroxide put in suspension »

After 16 hours of suspension polymerization with a With a stirring speed of 120 rpm, 25 g of graft copolymer with a global acrylonitrile content of $ 9 were obtained. It was assumed or estimated that the during the block polymerization grafts formed are formed by alternating copolymers, while those formed in suspension consist of random copolymers.

Example 7

In a reaction vessel analogous to that of Example 1, 5 g of polybutadiene (dissolved in 100 ml of toluene); 0.3 mole Styrene with 0.2 g of benzoyl peroxide and then 0.3 mole of methyl methacrylate with zinc chloride (0.03 mol) dissolved therein.

The flushed through by a stream of nitrogen, the reaction vessel was maintained for 16 hours at ⁰ C 6o.

The overall conversion of methyl methacrylate and styrene amounted under these conditions to 80 wt -.% Of the monomers used.

From the analysis of the copolymer it can be estimated that the grafts are formed by alternating "copolymers" which contain equimolar amounts of styrene and methyl methacrylate.

In the above examples, nuclear magnetic resonance testing the · products are closed that the after

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the grafts obtained by the process according to the invention Own "motifs" or units, of which at least 50 # alternate regularly.

As was said above, it is clear that _ the examples are given for illustration purposes only and are accessible to numerous modifications to be made by the person skilled in the art are without thereby departing from the scope of the invention. In particular, it is clear that the invention is not to a single alternating copolymer of a single polar vinylic monomer and a single vinyl aromatic monomer is, just as little as a single complexing agent, a single radical initiator or a single one Elastomer. In particular, mixtures, copolymers or terpolymers based on the in the context of the Description of the named polymers (e.g. polybutadiene / polyisoprene) use.

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Claims (1)

- 20 - Claims 1. Graft copolymers, characterized by an elastomer substrate with side chains, which by at least _; . a copolymer can be formed from at least one polar vinylic monomer and one vinylaromatic monomer, the units or motifs of which alternate by at least 50%. · 2. Graft copolymers according to claim 1, characterized in that the side chains fixed on the elastomer by at least an alternating copolymer of acrylonitrile and styrene or of methyl methacrylate and styrene are formed, 3. Graft copolymers according to claim 1 or 2, characterized in that that the elastomer substrate by polybutadienes, carboxylated polybutadienes, polyisoprenes, polyisobutylene and its copolymers with isoprene or butadiene or terpolymers of the ethylene / propylene / diene type is formed on the side chains formed by the alternating copolymers are grafted on. Process for grafting alternating copolymers of at least one polar vinylic monomer or one its derivatives or substituted compounds and at least one vinyl aromatic monomer or one of its derivatives or substituted compounds on one or more elastomers with the formation of graft copolymers Claim 1, characterized in that one or more elastomer (s) with at least one polar vinylic monomer or one of its derivatives or substituted compounds 2 0982 7/096 0 fertilize and at least one vinyl aromatic monomer or one of its derivatives or substituted compounds in the presence of at least one metal derivative capable of complex formation with the polar monomer is capable of bringing together to form a graft copolymer. 5. The method according to claim 4, characterized in that Acrylonitrile or methyl methacrylate can be used as polar vinylic monomers. 6. The method according to claim 4 or 5 *, characterized in that that styrene is used as the vinyl aromatic monomer. 7. Method according to one of claims 4 to 6, characterized in that that the complexing agent for the monomer is a metal halide and preferably a halide of a metal from the group of zinc, cadmium, aluminum and tin and in particular Zirik chloride is used. '8th. Method according to claim 7, characterized in that the proportion of complexing agent is from 0.005 to 10 and in particular from 0.05 to 1 mol per mol of polar monomer. 9. The method according to any one of claims 4 to 8, characterized in that that at least one free radical initiator is additionally present in the reaction mixture, which is preferably is formed by an organic peroxide and in particular by benzoyl peroxide. 10. The method according to claim 9 *, characterized in that the proportion of radical initiator between 0.0001 and 0.05 and 209 827/0960 in particular between 0.0005 and 0.01 mol per mol total of the monomers used. 11. The method according to any one of claims 4 to 10, characterized in that that the grafting reaction in an inert solvent and in particular is carried out in benzene or cyclohexane. 12. The method according to any one of claims 4 to 10, characterized in that the vinyl aromatic monomers as _; Solvent medium is used for the grafting reaction. 13 · The method according to any one of claims 4 to 10, characterized characterized in that the grafting reaction in bulk or in the Block is carried out up to a given degree of conversion, which is followed by suspension or emulsion polymerization connects. l4. Method according to one of Claims 4 to 13 * thereby characterized in that the grafting reaction in the presence of a Chain transfer agent, especially in the presence of tert-dodecyl mercaptan. 15 · The method of any of claims 4 to 14, characterized in that the grafting reaction temperature between 0 and 150 ° C and in particular between 20 and 100 ⁰ C. 16. The method according to any one of claims 4 to 15 »thereby characterized in that the reaction is carried out in an inert atmosphere to avoid oxidation of the elastomer can be. 209827/0960 17. The method according to any one of the claims! 4 to 16, characterized in that the elastomer under the carboxylated polybutadienes, polybutadienes, polyisoprenes, polyisobutylene and its copolymers with isoprene and butadiene and the terpolymers s type ethyl / propylene / diene is selected. 209827/0960