The invention relates to novel alloys between a polyolefin polymer and a polymer non-miscible therewith, in which alloys a graft copolymer is used as compatibilizer, as well as a pro¬ cess for producing such alloys.

More specifically, the invention relates to novel polymer alloys of a Polymer 1 consisting of a polypropylene polymer, a Polymer 2 containing aromatic monomeric units as repeating unit(s) in the polymer chain and/or functionality which is complementary to hydroxyl, and a compatibilizer consisting of a reaction product of a functionalized polypropylene polymer and a novolak polymer, as well as a process for producing such polymer alloys. The new polymer alloys combine properties which characterize polypropylene polymers with properties characterizing the Polymer 2 that has been utilized.

Although the polypropylene polymers exhibit a number of good properties which make them useful for many applications, there is a great demand for polymer materials combining the proper¬ ties of the polypropylene materials with the properties of other kinds of polymers. Thus, it is often desirable to pro¬ duce a blend or an alloy of a polypropylene polymer with such other kind of polymer so as to obtain a product having an optimal balance between the properties of the two components. However, to produce such blends or alloys wherein one of the components is a polypropylene polymer often presents problems, because the polypropylene polymer will often be incompatible with the other kind of polymer which it is desired to use. A compatibilization can be especially difficult in cases where the other kind of polymer contains repeating aromatic monome¬ ric units as repeating unit(s) in the polymer chain, and is selected from e.g. polyphenylene ethers (PPE), polyphenylene oxides (PPO), polybutylene terephthalates (PBT), polyethylene terephthalates (PET) , polystyrenes (PS), aromatic and •amor¬ phous polyamides, polycarbonates (PC), and phenol-formaldehyde thermoplastics and copolymers thereof (PF) .

It has been usual in such cases to use compatibilizers, which directly increase the compatibility between the dissimilar polymers by participating in reactions with the polymers, or by entering into physical/chemical interactions with them. For instance, it is well known to use as compatibilizers polyole- fins grafted with maleic anhydride, acrylic acid, allyl-2,3- epoxyalkyl ether, vinyl silanes and other vinyl monomers. With such compatibilizers, a certain degree of compatibility has been achieved between polypropiiene polymers and polymers of the above-mentioned kind. However, it has been difficult to achieve an acceptable degree of compatibility in cases where the other kind of polymer material has been lacking a suffi¬ ciently good complementary chemistry.

Although alloys of polyolefin polymers are previously known for various applications, such alloys have not previously made use of graft copolymers of a functionalized polypropylene polymer and a novolak polymer as a compatibilizer.

GB 1567375 (Du Pont, 1980) teaches blends of thermosetting resins with flexible copolymers of ethylene with various co- monomers. The aim is to produce a blend having a low thermal deformation and being useful especially for casting. Polypro¬ pylene is not mentioned in the patent and polymer alloying technology is not utilized.

EP 416526 (Takeda Chem. Ind., 1989) discloses an addition of phenol-formaldehyde resols to thermoplastic resins to reduce the occurrence of cure shrinkage in the casting of sheets. No mention is made of polypropylene and compatibilization tech¬ nology.

SE 387355 (Dart Ind. Inc., 1976) teaches composites of poly¬ olefin and glass. Phenol-formaldehyde polymers and alloying technology are not mentioned.

It has now been possible, by means of certain novel compati¬ bilizers consisting of graft copolymers of a functionalized polypropylene polymer and a novolak polymer, and through an

appropriate selection of alloying partners and alloying con¬ ditions, to produce polyolefin alloys exhibiting a repro¬ ducible broad range of desired properties, especially with improved E module and/or impact strength, which properties make these alloys useful for a number of applications.

Thus, the invention provides a polymer alloy having a melt index in the range of 0.1-400 g/10 min at 230 °C/2.16 kg, especially 3-100 g/10 min at 230 °C/2.16 kg, which polymer alloy is essentially produced from:

- a Polymer 1 consisting of a polypropylene polymer, and

- a Polymer 2, used in an amount of 0.5-95 wt% of the amount of Polymer 1, and containing aromatic monome- ric units as repeating unit(s) in the polymer chain and/or having functionality which is complementary to hydroxyl, including functionality allowing for secon¬ dary chemical bonds, and - a compatibilizer consisting of a reaction product of:

(1) a functionalized polypropylene polymer having functional groups capable of reacting with hydroxyl groups, and having a melt index MI in the range of 0.1-450 g/10 min at 230°C/2.16 kg, and a functionality of 0.1-10 wt%, and

(2) a novolak polymer having a weight average molecular weight M., of 750-40.000 g/mole, formed by reacting (a) phenol and/or one or more phenol derivatives with (b) formaldehyde or acetone, which reaction product contains 1-75 wt% of blocks of the novolak polymer and has a melt index in the range of 0.1-400 g/10 min at 230 °C/2.16 kg.

The polymer alloy is produced by mixing Polymer 1, Polymer 2 and the compatibilizer with one another in a molten state under an inert atmosphere, e.g. in a nitrogen atmosphere, in a batch blender or an extruder, using melt temperatures of 160 to 340 °C, especially from 180 to 280 °C.

Preferably, the polymer alloy is produced by mixing and mel¬ ting the three components in an extruder, by either

(a) introducing Polymer 1, Polymer 2 and the com¬ patibilizer together into the hopper of the extruder, optio- nally as a premixture, or separately, or

(b) introducing Polymer 1 into the hopper of the extruder, optionally together with the compatibilizer, and introducing Polymer 2 at a position downstream of the hopper, where the components already added are in a molten state, optionally together with the compatibilizer, or

(c) introducing Polymer 2 into the hopper of the ex¬ truder, optionally together with the compatibilizer, and in¬ troducing Polymer 1 at a position downstream of the hopper, where the components already added are in a molten state, optionally together with the compatibilizer, and then processing the mixture in the extruder until the polymers have been sufficiently mixed and/or reacted with one another, and cooling and granulating the extruded product.

The polypropylene polymer which is used as Polymer 1 in the polymer alloy may advantageously consist of a propylene homo- polymer or a copolymer of propylene with ethylene and/or buta¬ diene. These preferred polypropylene polymers have a melt index MI in the range of 0.1-100 g/10 min at 230 "C/2.16 kg, especially in the range of 0.35-50 g/10 min at 230 "C/2.16 kg, and a weight average molecular weight in the range of 10.000-500.000 g/mole.

The polymer containing aromatic monomeric units as repeating unit(s) in the polymer chain, and which is used as Polymer 2 in the polymer alloy, may advantageously be selected from polyphenylene ethers (PPE), polyphenylene oxides (PPO), poly- butylene terephthalates (PBT), polyethylene terephthalates (PET), polystyrenes (PS) , polycarbonates (PC) , aromatic and amorphous polyamides (PA), and phenol-formaldehyde thermoplas¬ tics and copolymers thereof (PF) . The selected Polymer 2 should have viscosity properties such that its viscosity under the extrusion conditions is in the range of 0.1 to 10 times the viscosity of the polypropylene polymer used as Polymer 1.

Useful kinds of Polymer 2 having "a functionality which is complementary to hydroxyl", are e.g. polybutylene tereph¬ thalate having free terminal carboxyl groups, polyamide having free terminal carboxyl groups and free terminal amine groups, and polyethylene terephthalate having free terminal carboxyl groups.

As already mentioned, the amount of Polymer 2 in relation to the amount of Polymer 1 is from 0.5 to 95 wt%. More par- ticularly, the amount of Polymer 2 is from 1 to 75 wt%. The compatibilizer is used in an amount of 1-40 wt%, preferably 5- 20 wt%, of the total composition.

The produced polymer alloy of the invention is a product in which Polymer 1, Polymer 2 and the compatibilizer are physi¬ cally and/or chemically bonded to one another. The polymer alloy exhibits the following characteristics:

E module: 300-3500 MPa. Elongation at break: 0.5-600%.

Impact strength; total energy in drop test: 0.5-60 J (0 °C).

The chemical structure of the graft copolymer of the invention may be illustrated by the formula:

H C Z

I

0

wherein X is a group derived from e.g. maleic anhydride (MAH), glycidyl methacrylate (GMA), or acrylic acid, and Z is hydro¬ gen, C _j^ -Cs alkyl, hydroxyl, or C-^Cs alkoxy. Instead of -CH ₂ -C—CH ₂ - groups between the benzene nuclei, -CH ₂ - groups may be present. The balance between -CH ₂ -0-CH ₂ - groups and -CH ₂ - groups depends on the synthesis conditions.

The compatibilizers utilized in the invention can be produced as follows:

(i) 99-25 parts by weight, especially 95-60 parts by weight, of a functionalized polypropylene polymer having functional groups capable of reacting with hydroxyl groups, and having a melt index MI in the range of 0.1-450 g/10 min at 230 °C/2.16 kg, espe¬ cially 5-200 g/10 min at 230 °C/2.16 kg, and a func-

tionality of 0.1-10 wt%, especially 0.4-4.0 wt%, and 1-75 parts by weight, especially 1-40 parts by weight, of a novolak polymer having a weight average molecular weight M _w of 750-40.000 g/mole, especially s 1000-25.000 g/mole, formed by reacting (a) phenol and/or one or more phenol derivatives with (b) for¬ maldehyde or acetone, are mixed and molten together under an inert atmosphere, pre¬ ferably with simultaneous kneading, o (ii) the molten mixture is kneaded under an inert atmosphere until the functionalized polypropylene polymer has reacted with the novolak polymer to the desired degree of con¬ version, and

(iii) the kneaded product is cooled and optionally 5 granulated.

The compatibilizers are produced at melt temperatures in the range of 160-275 °C, especially in the range of 180-240 °C. Catalyst is added as required. Usually, 0.01-2.5 wt%, espe¬ 0 cially 0.1-0.5 wt%, of a catalyst is added, and the catalyst may be selected e.g. from:

(a) compounds having the general formulae:

o wherein R ₆ , R ₇ , R ₈ , R ₉ and R ₁₀ are identical or non-identical and are selected from hydrogen and alkyl having 1 to 3 carbon atoms, and R _X1 is alkyl having 1 to 3 carbon atoms,

(b) hydroxides and oxides of mono-, di- and trivalent cations, and 5 (c) organic and inorganic mono- and diprotic acids, such as formic acid, oxalic acid and sulphuric acid.

Preferably, the compatibilizers are produced by the steps of: (i) reacting the functionalized polypropylene polymer

in a molten state with the novolak polymer under an inert atmosphere in an extruder, by either (a) introducing the func¬ tionalized polypropylene polymer and the novolak polymer into the extruder through the hopper, in the form of a premixture s or separately, or (b) introducing the functionalized polypro¬ pylene polymer into the extruder through the hopper and intro¬ ducing the novolak polymer into the extruder through an aper¬ ture in the cylinder wall of the extruder at a position down¬ stream of the hopper, where the polypropylene polymer is in a o molten state,

(ii) processing the mixture in the extruder until the novolak polymer has reacted with the functionalized polypropy¬ lene polymer to the desired degree of conversion, and

(iii) extruding, cooling and optionally granulating the mixture.

The functionalized polypropylene polymer which is capable of reacting with hydroxyl groups, and which is used in the pro¬ duction of the compatibilizer, is preferably produced from a polypropylene homopolymer or a copolymer of propylene with ethylene and/or butadiene. These preferred neat polypropylene polymers have a melt index MI in the range of 0.1-100 g/10 min at 230 "C/2.16 kg, especially in the range of 0.35-10 g/10 min at 230 "C/2.16 kg, and a weight average molecular weight in the range of 10.000-500.000 g/mole. The functionalization of the polypropylene polymer may be obtained by grafting with a compound selected from e.g. maleic anhydride, glycidylalkyl acrylates, acrylic acid, vinyl silanes and other vinyl mono¬ mers. The functionalized polypropylene polymer may advantage- ously be selected from the following materials:

(1) Polypropylene polymers grafted with an epoxyalkyl acrylate compound using an organic peroxide as a radical former, and having a melt index MI in the range of 1-250 g/10 min at 230 °C/2.16 kg, especially in the range of 3-40 g/10 min at 230 °C/2.16 kg, and a graft ratio of 0.2-10 wt%, especially 0.8-2.5 wt%, and having been produced by:

(i) said polypropylene polymer having been mixed with the organic peroxide and the mixture having been mol-

ten under an inert atmosphere, preferably with knea¬ ding of the mixture, (ii) an epoxyalkyl acrylate com¬ pound having the general formula:

wherein R is H or C _ ₄ alkyl, and n is an integer of 1 to 6, having been introduced into the molten mixture, (iii) said mixture having been kneaded until the epoxyalkyl acrylate compound has reacted with the polypropylene polymer to a desired graft ratio, and (iv) the kneaded product having been cooled and gra¬ nulated. For a more detailed description of this graft polypropylene polymer and the production thereof, a reference is made to Norwegian Patent Application No. 924746.

(2) Polypropylene polymers containing 0.1-4 wt%, espe¬ cially 0.4-1.2 wt%, of maleic anhydride, and having a melt index MI of 3-450 g/10 min at 230 "C/2.16 kg, especially 5-250 g/10 min at 230 "C/2.16 kg. Such maleic anhydride-functionalized polypropylene poly¬ mers are sold by several polymer producers.

(3) Polypropylene polymers containing 0.1-4 wt% acrylic acid grafted thereon.

(4) Polypropylene polymers containing 0.1-4 wt% allyl- 2,3-epoxyalkyl ether grafted thereon.

The novolak polymers used in the production of the compati¬ bilizer have a molar ratio of phenol compound to formaldehyde in the range of 1:0.5 to 1:0.95, and a similar ratio when ace¬ tone is used instead of formaldehyde. Preferably, a novolak polymer is used which is produced by reaction of (a) one or more phenol compounds having the general formula:

wherein R _lr R ₂ , R ₃ , R ₄ and R ₅ are identical or non-identical and are selected from hydrogen, alkyl having 1 to 3 carbon atoms, and hydroxyl, with (b) a compound selected from formaldehyde and acetone.

The compatibilizers that are used in the polymer alloys of the invention and their production are described in more detail in Norwegian Patent Application No. 941558.

The following examples and comparison examples further illustrate the invention. In said examples, three different grades of polypropylene copolymers were used as Polymer 1, viz. :

Statoil P 410, which is a copolymer of propylene with ethylene, having a melt index MI of 2.0 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers,

Statoil P 401, which is a copolymer of propylene with ethylene, having a melt index MI of 0.35 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers, and

Statoil P 330, which is a copolymer of propylene with ethylene, having a melt index MI of 5.0 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers.

Two of the new compatibilizers, designated as "Compatibilizer I" and "Compatibilizer II", were used in the Examples. Their preparation is described below.

Preparation of Compatibilizer I.

Graft copolymer of MAH-qrafted PP and novolak polymer (PF) . A maleic acid-grafted polypropylene (PP) containing 1.2 wt% of grafted MAH (maleic anhydride) and having a melt index MI of 50 g/10 min at 230 "C/2.16 kg was reacted with a novolak poly-

mer consisting of a phenol-formaldehyde polymer (PF) having a molar ratio of formaldehyde to phenol of 0.9 and a molecular weight of 7500 g/mole, in an extruder with no catalyst pre¬ sent. The novolak polymer was introduced in an amount of 17 s wt% based on the total mixture. The extruder was a twin screw extruder of the type "Clextral BC 21" having 25 mm co-rotating screws. The hopper was flushed with nitrogen gas in order that the preparation should be carried out in an essentially inert atmosphere. The screw speed was 200 r.p.m. and the extrusion o speed was 3 kg/h. All raw materials were introduced gravimet- rically into hopper 1. The temperature profile of the extruder was maintained in the range of 195 to 210 °C. A graft copoly¬ mer with 2.5 wt% grafted PF was obtained.

Preparation of Compatibilizer II.

Graft copolymer of GMA-qrafted PP and novolak polymer (PF) . The above procedure was followed, except that the maleic acid- grafted polypropylene was replaced by a glycidyl methacrylate- grafted polypropylene having a content of grafted glycidyl methacrylate (GMA) of 1.25 wt%, having a melt index MI of 28 g/10 min at 230 "C/2.16 kg, produced in accordance with Nor¬ wegian Patent Application No. 924746. The novolak polymer (PF) was added in an amount of 17 wt%, based on the total mixture. A graft copolymer with 8.0 wt% grafted PF was obtained.

All of the following examples and comparison examples were carried out according to the following procedure.

Procedure: in a twin screw extruder of the type "Clextral BC 21" having 25 mm co-rotating screws a polypropylene polymer (Polymer 1) is reacted/mixed with an alloying partner (Polymer 2), with or without addition of a compatibilizer. Polymer 1 is introduced into hopper 1, and Polymer 2 is introduced into hopper 2 ( ownstream of hopper 1) . The hoppers are flushed with nitro¬ gen gas in order that the mixing and kneading should take place in an essentially inert atmosphere. All raw materials are introduced gravimetrically into the respective hoppers. The screw speed of the extruder is 200 r.p.m. and the extru-

sion speed is 3 kg/h.

Examples 1.1 - 1.5 (Comparison Examples).

The above procedure was followed. Polymer 1 was a polypropy- lene copolymer of the grade Statoil P 401 having a melt index MI of 0.35 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers. Polymer 2 was a polyphenylene ether having a vis¬ cosity of 1000 Pa.s at 1000 s" ^x /265 "C. Polymer 2 was added in amounts of 5, 25, 50, 75 and 95 wt°-, respectively, based on the total mixture. No compatibilizer was used. The temperature profile of the extruder was maintained in the range of 225 to 275 "C. The components added, the amounts thereof, and the results are given in Table 1 below.

Examples 1.6 - 1.10.

Examples 1.1-1.5 were repeated, except that 2.5 wt% of the above described Compatibilizer I, based on the total mixture, were introduced into hopper 1 together with the polypropylene copolymer, with adjustments of the amounts of Polymer 1 and Polymer 2 as required, maintaining the same weight ratio be¬ tween them. Otherwise, the operation conditions were as indi¬ cated in Examples 1.1-1.5. The components added, the amounts thereof, and the results are given in Table 1 below.

Examples 1.11 - 1.13.

Examples 1.1-1.3 were repeated, except that 7.5 wt% of the above described Compatibilizer I, based on the total mixture, were introduced into hopper 1 together with the polypropylene copolymer, with adjustments of the amounts of Polymer 1 and Polymer 2 as required, maintaining the same weight ratio be¬ tween them. Otherwise, the operation conditions were as given in Examples 1.1-1.3. The components added, the amounts there¬ of, and the results are given in Table 1 below.

Example 1.14.

Example 1.12 was repeated, except that 7.5 wt% of the above described Compatibilizer II, based on the total mixture, were introduced into hopper 1 together with the polypropylene copo¬ lymer, with adjustments of the amounts of Polymer 1 and Poly-

mer 2 as required, maintaining the same weight ratio between them. Otherwise, the operation conditions were as given in Examples 1.12. The components added, the amounts thereof, and the results are given in Table 1 below.

Examples 2.1 - 2.5 (Comparison examples).

The above procedure was repeated. As Polymer 1 there was used a polypropylene copolymer of the grade Statoil P 410 having a melt index MI of 2.0 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers. As Polymer 2 there was used a polybutyl- ene terephthalate having a melt index MI of 34 g/10 min at 250 "C/21.2 N. Polymer 2 was added in amounts of 5, 25, 50, 75 and 95 wt%, respectively, based on the total mixture. No com¬ patibilizer was used. The temperature profile of the extruder was maintained in the range of 225 to 265 °C. The components added, the amounts thereof, and the results are given in Table 2 below.

Examples 2.6 - 2.10. Examples 2.1-2.5 were repeated, except that 2.5 wt% of the above described Compatibilizer I, based on the total mixture, were introduced into hopper 1 together with the polypropylene copolymer, with adjustments of the amounts of Polymer 1 and Polymer 2 as required, maintaining the same weight ratio be- tween them. Otherwise, the operation conditions were as given in Examples 2.1-2.5. The components added, the amounts there¬ of, and the results are given in Table 2 below.

Examples 2.11 - 2.13. Examples 2.1-2.3 were repeated, except that 7.5 wt% of the above described Compatibilizer I, based on the total mixture, were introduced into hopper 1 together with the polypropylene copolymer, with adjustments of the amounts of Polymer 1 and Polymer 2 as required, maintaining the same weight ratio be- tween them. Otherwise, the operation conditions were as given in Examples 2.1-2.3. The components added, the amounts thereof, and the results are given in Table 2 below.

Example 2 . 14 .

The procedure of Example 2.12 was followed, except that 7.5 wt% of the above described Compatibilizer II, based on the total mixture, were introduced into hopper 1 together with the s polypropylene copolymer, with adjustments of the amounts of Polymer 1 and Polymer 2 as required, maintaining the same weight ratio between them. Otherwise, the operation conditions were as given in Example 2.12. The components added, the amounts thereof, and the results are given in Table 2 below. 0

Examples 3.1 (comp. ex.) and 3.2 - 3.3.

The above procedure was followed. As polymer 1 there was used a polypropylene copolymer of the grade Statoil P 401 having a melt index MI of 0.35 g/10 min at 230 "C/2.16 kg, premixed s with standard stabilizers. As Polymer 2, a low-viscous poly¬ carbonate having a melt index MI of 15 ml/600 s at 260 "C/1.2 kg was used. Polymer 2 was added in an amount of 1 part by weight to 3 parts by weight of polymer 1. In Example 3.1 (com ^¬ parison example), no compatibilizer was used, whereas 5 wt% of 0 the above described Compatibilizer I, based on the total mix¬ ture, were used in Example 3.2, and 10 wt% of the same Compa¬ tibilizer I were used in Example 3.3. The temperature profile was maintained in the range of of 250 to 295 °C. The com¬ ponents added, the amounts thereof, and the results are given 5 in Table 3 below.

Examples 3.4 (comp. ex. ) and 3.5.

The procedures were similar to those of Examples 3.1 and 3.2.

As polymer 1 there was used a polypropylene copolymer of the 0 grade Statoil P 410 having a melt index MI of 2.0 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers. As Polymer 2, a polystyrene having a melt index MI of 3.5 g/10 min at 205 "C/2.16 kg was used. Polymer 2 was added in an amount of 1 part by weight to 3 parts by weight of polymer 1. In Example 5 3.4 (comparison example), no compatibilizer was used, whereas 5 wt% of the above described Compatibilizer I, based on the total mixture, were used in Example 3.5. The temperature pro¬ file was maintained in the range of of 210-225 "C. The com¬ ponents added, the amounts thereof, and the results are given

in Table 3 below.

Examples 3.6 (comp. ex. ) and 3.7.

The procedures were similar to those of Examples 3.1 and 3.2. As polymer 1 there was used a polypropylene copolymer of the grade Statoil P 330, having a melt index MI of 5.0 g/10 min at 230 "C/2.16 kg, premixed with standard stabilizers. As Polymer 2, a novolak polymer consisting of a phenol-formaldehyde poly¬ mer (PF) having a viscosity of 150 Pa.s at 10 Hz/210 "C was used. Polymer 2 was added in an amount of 1 part by weight to 3 parts by weight of polymer 1. In Example 3.6 (comparison example), no compatibilizer was used, whereas 5 wt% of the above described Compatibilizer I, based on the total mixture, were used in Example 3.7. The temperature profile of the ex- truder was maintained in the range of of 200-225 "C. The com¬ ponents added, the amounts thereof, and the results are given in Table 3 below.

In the following assessments of the results obtained in the Examples, references are made to the appended drawings, wherein:

Fig. 1 shows the E module and the impact strength as a function of the content of polyphenylene ether (PPE) in the polymers of the series of examples 1.1-1.14; Fig. 2 shows the E module and the impact strength as a function of the content of polybutylene terephthalate (PBT) in the polymers of the series of examples 2.1-2.14;

Fig. 3 shows the impact strength, plotted as a func¬ tion of the E module, of the polymers of the series of exampl- es 1.1-1.14;

Fig. 4 shows the impact strength, plotted as a func¬ tion of the E module, of the polymers of the series of examp¬ les 2.1-2.14; and

Fig. 5 shows the impact strength, plotted as a func- tion of the E module, of the polymers of the series of Examp¬ les 3.1-3.7.

Assessment of the results obtained in Examples 1.1-1.14.

(Polymer 2: Polyphenylene ether (PPE) ) . The results obtained in Example 1.1-1.14 are shown in Table 1 and the appended Figures 1 and 3. It can ben seen from Fig. 1 that the E module increases significantly with increased addi¬ tion of compatibilizer when the alloying partner (Polymer 2), which in this case is a polyphenylene ether (PPE), is used in amounts of 5 to 50 wt%, based on the polymer alloy. When PPE is used in amounts exceeding 50 wt%, the effect of the com- patibilizer decreases and becomes small and negligible. The effect of the amount of the compatibilizer on the E module is highest in the range of 5 to 40 wt% PPE.

The impact strength values that can be seen from Fig. 1 also show that the compatibilizer is effective in the range of up to 50 wt% PPE and has a maximum of effectiveness in the range of up to 35-40 wt% PPE. Addition of the compatibilizer in amounts exceeding 2.5 wt% has no great effect on the impact strength values in this range. With amounts of PPE exceeding 50 wt% the effect of the compatibilizer on the impact strength is small or negligible.

Fig. 3 shows the impact strength as a function of the E module. It can be seen that the E module of the polymer blends/alloys (1.1-1.14) increases substantially in relation to that of the non-modified polypropylene polymers Statoil P 401, P 410 and P 330. With a compatibilizer present, the im¬ pact strength is improved for the majority of the alloys, as compared with a binary system of polymer PP and PPE (Examples 1.1-1.5).

Using a compatibilizer (II) based on GMA-functionalized PP and novolak polymer (PF) in a polymer alloy containing 23.1 wt% PPE (Example 1.14) results in a higher stiffness (E module) but a lower impact strength than the corresponding values exhibited by a similar polymer alloy using a compatibilizer (I) based on MAH-functionalized PP and novolak polymer (PF) (Example 1.12).

The PPE that was used did not contain terminal groups comple¬ mentary to hydroxyl and no reaction between the functionalized polypropylene polymer and the PPE could therefore be expected. However, the effect of the compatibilizer could be explained s by an orbital overlapping of the phenyl rings in the phenol groups and the repeating unit in the PPE and any secondary bonding forces between the compatibilizer and the PPE.

Assessment of the results obtained in Examples 2.1-2.14. o (Polymer 2: Polybutylene terephthalate (PBT) ) .

Table 2 and the appended Figures 2 and 4 show the results obtained in Examples 2.1-2.14. Fig. 2 shows the E module and the impact strength of the polymers as a function of the con¬ tent of PBT in the alloy, and Fig. 4 shows the impact strength s of the polymers plotted as a function of the E module.

It can be seen from Fig. 2 that the E module increases signi¬ ficantly with increasing addition of compatibilizer for con¬ tents of polybutylene terephthalate (PBT) in the range of o about 20 wt% to up to 100 wt% of the polymer alloy.

Fig. 2 shows that an addition of 2.5 wt% of compatibilizer results in a positive effect on the impact strength when 50 wt% of PBT or more is used. Fig. 2 also shows that addition of 5 the compatiblizer in an amount of 7.5 wt% gives a positive effect on the impact strength in the range of up to about 50 wt% of PBT.

Fig. 4 shows the impact strength of the polymer alloy plotted o as a function of the E module. It can be seen that the E module of the polymer alloys is substantially improved com¬ pared to that of the non-modified polypropylene polymers (Statoil P 401, P 410, P 330). For the majority of the polymer alloys the impact strength values are increased with com- 5 patibilizers present, as compared to a binary system of poly¬ mer PP and PBT without compatibilizer (Examples 2.1-2.5). In particular, polymer alloys having a low content of PBT exhibit a substantially increased E module compared to a neat polypro¬ pylene copolymer, while the impact strength is maintained or

increased. Even with higher contents of PBT the compatibilizer gives a significant increase in the E module and the impact strength.

5 Polybutylene terephthalate (PBT) contains terminal groups that are complementary to hydroxyl, and a reaction between the functionalized polypropylene polymer and the PBT was therefore to be expected. In addition, the effect of the compatibilizer could be explained by an orbit?1 overlapping between the phe- ιo nyl rings in the phenol groups of the compatibilizer and the repeating unit of the PBT, as well as by secondary linkages. The fact that the effect of the compatibilizer is higher in the system of Examples 2.6-2.14, in which the alloying partner is polybutylene terephthalate (PPE), than in the above-descri- i5 bed system of Examples 1.6-1.14, in which the alloying partner is polyphenylene ether (PPE), can be explained by the fact that the bonding forces in covalent bonds are substantially stronger than those existing in secondary bonds (orbital over¬ lapping) .

20

In a polymer alloy containing 23.1 wt% of PBT, a compatibili¬ zer based on GMA-functionalized PP and novolak polymer (PF) (Example 2.14) gives a somewhat lower stiffness (E module) but an improved impact strength than a compatibilizer based on a 25 MAH-functionalized PP and a novolak polymer (PF) (Example 2.12).

Thus, a comparison of Examples 1.6-1.14 to Examples 2.6-2.14 shows that the compatibilizer provides an effect for PP/PPE o polymer alloys as well as for PP/PBT alloy systems, but it shows that the effect of the compatibilizer is higher in a system in which the secondary polymer has a complementary che¬ mistry (which is the case for PBT), and any additional secon¬ dary bonding forces such as π-π orbital overlapping, hydrogen

35 bonds, etc.

Assessment of the results obtained in Examples 3.1-3.7. (Polymer 2: Polycarbonate (PC) , polystyrene (PS) . novolak polymer (PF) .

The results obtained in Examples 3.1-3.7 can be seen from Table 3 and the appended Fig. 5 showing the impact strength of the polymers plotted as a function of the E module.

(1) The system PP + PC.

A comparison of Example 3.1 with Examples 3.2 and 3.3 in Table 3 that the E module is not noticeably altered in a system of PP + PC (polycarbonate) when a compatibilizer is used, but that the impact strength is increased somewhat in relation to that of the binary system, viz. from 3.2 J to 4.5-4.6 J at 0 "C.

Fig. 5 shows that the E module increases substantially in re¬ lation to the non-modified polypropylene copolymers Statoil P 401, P 410, P 330. The impact strength of the polymer alloys containing a compatibilizer is higher than for the correspon- ding binary systems of PP + PC, but it is lower than for the neat polypropylene copolymer (Statoil P 401, P 410, P 330).

The system PP + PS.

Table 3 shows that the E module increases noticeably in a sys- tem of PP + PS (polystyrene) when a compatibilizer is used, viz. from 1666 MPa to 1880 MPa, whereas the impact strength is not altered or is slightly reduced in relation to that of the binary system PP + PS, viz. from 1.6 J to 1.5 J at 0 "C. This can also be seen from Fig. 5, where the impact strength of the polymers is plotted as a function of the E module.

The system PP + PF.

Table 3 shows that the E module increases noticeably in a sys¬ tem of PP + PF (novolak polymer) when the system also contains 5 wt% of compatibilizer, viz. from 1775 MPa to 1950 MPa. The impact strength increases in relation to that of the binary system PP + PF, viz. from 1.5 J to 2.2 J at 0 °C. This can also be seen from Fig. 5.

Neither the polycarbonate (PC) , the polystyrene (PS) nor the novolak polymer (PF) has groups complementary to the hydroxyl groups of the compatibilizer and it was therefore expected that the effect of the compatibilizer would be less than in a reactive system such as the system PP + PBT. However, the compatibilizer had an effect on the E module of all the three alloying systems PP + PC, PP + PS, and PP + PF, and also on the impact strength of the systems PP + PC and PP + PF. The fact that the compatibilizer has no effect on the E module of the system PP + PS can be explained by the fact that PF is relatively non-polar compared to both PC and PF, and that it cannot be expected, therefore, that any other secondary bon¬ ding forces than τι-π orbital overlapping would occur between the compatibilizer and the PS. On the other hand, other secon- dary linkages such as hydrogen bonds, etc. could be expected between the compatibilizer and PC and PF, respectively.