' unsaturated polymers of norbornene dicarboximides and

5 copolymers of norbornene dicarboximide and norbornene dicarboxylic acid, anhydride, mono ester or diester. Also disclosed are blends of such polymers and copolymers with polymers having acid-reactive functionality, e.g. a polyamide such as nylon-6 or

10 ^• nylon-6,6 and, optionally, a rubber toughening agent. Also disclosed are methods of using such blends for high performance thermoplastic applications. BACKGROUND OF THE INVENTION Polyamides, e.g. nylon-6 and nylon-6,6, are

15 typically characterized as semicrystalline thermoplastics and are widely used in a wide range of applications. Due to high strength polyamides are commonly and advantageously used as tire cord, carpet fiber, tough fabrics, etc. However, due to other

20 properties polyamides have limited use in other engineering thermoplastic applications. For instance, due to low impact strength, polyamides often require toughening, e.g. with rubber impact modifier, to provide sufficient impact strength required of many

25 molded parts. Polyamides also typically have unsatisfactory load bearing properties at moderate to high temperatures due to the low glass transition temperature of the polyamide. Heat distortion temperature determined under the force of a load

30 (typically 1820 Kpa) is widely known by the acronym "HDTUL". For instance, nylon-6 and nylon-6,6 have HDTUL in the range of 60 to 80 °C. Rubber-modified polyamides, having high impact strengths that commend their use for many engineering thermoplastic

35 applications, generally have even lower HDTUL. Metathesis ring-opening polymers of norbornene * dicarboximides, especially the N-methyl,

N-ethyl, N-propyl and N-phenyl i ides, exhibit high glass transition temperatures, e.g. about 200 °C, and high HDTUL, e.g. about 150 to 180 °C. What I have discovered is that such metathesis ring-opening polymers of norbornene dicarboximides can be effectively blended with polyamides to provide blends having the attendant advantageous properties of polyamides but with an exceptionally high heat distortion temperature. Even more advantageous blends - are achieved when the metathesis ring-opened unsaturated polymer of norbornene dicarboximide includes a small amount of an acid containing species.

SUMMARY OF THE INVENTION In one aspect this invention provides . polymer blends comprising a metathesis ring-opening polymerized unsaturated polymer of norbornene dicarboximide and a polyamide or other polymer having acid-reactive functionality. In another aspect this invention provides polymer blends comprising a metathesis ring-opening polymerized unsaturated copolymer of monomer units of norbornene dicarboximide and a norbornene carboxylic acid. Such copolymer can be used alone in blends with acid-reactive polymers or, alternatively, as a compatibilizer in blends of norbornene dicarboximide polymer and acid-reactive polymers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The polymer blends of this invention comprise polymers having acid-reactive functionality such as polyamides and metathesis ring-opening polymerized unsaturated polymers of a norbornene dicarboximide, e.g. about 10 to 90 parts by weight of polymer having acid-reactive functionality and, conversely, about 90 to 10 parts by weight of metathesis ring-opening polymerized unsaturated polymer. More preferred blends, depending on the desired properties, can comprise at least about 30

parts by weight of each polymer. Preferred polymers having acid-reactive functionality include polyamides having amine end groups such as nylon-6 or nylon-6,6 and, optionally, toughened polyamides, e.g. having 5 rubber toughening agents. Other useful acid-reactive functional polymers include polyesters having hydroxyl end groups.

The norbornene dicarboximide of the metathesis ring-opening polymerized polymers can be

10. alkyl, cycloalkyl or aromatic i ides. Polymers having advantageously high glass transition temperatures, e.g. above 150 °C, and preferably above 200 ^β C, include polymers and copolymers comprising monomer units of N-methyl, N-ethyl, N-propyl, N-isopropyl,

15 N-cyclohexyl or N-phenyl norbornene dicarboximide. Such polymers can be prepared by known methods for metathesis ring-opening polymerization of norbornene derivative monomers which provide unsaturated polymer. Especially preferred methods are disclosed by Hardiman 0 in WIPO International Publication Number WO 91/18938.

In preferred blends the metathesis ring- opening polymerized polymer comprises a copolymer of a norbornene derivative monomer having acid functionality that allows reactive interaction with . 5 polymers having acid-reactive functionality. Preferred metathesis ring-opening polymerized unsaturated copolymers comprise monomer units of norbornene dicarboximide and a norbornene carboxylic acid or ester. In more preferred copolymers the 0 norbornene carboxylic acid will comprise a dicarboxylic acid or the acid anhydride, mono ester or diester thereof. Although the amount of norbornene carboxylic acid functional monomer units in the copolymer can vary, preferred copolymer will generally 5 comprise less than about 10 mole percent of the acid monomer units, e.g. about 0.5 to 3 mole percent of

acid monomer units. Such compatibilizer copolymers can readily be prepared from mixtures of monomer using metathesis ring-opening polymerization methods generally useful for norbornene derivative monomers. The acid-functional copolymers of this invention can be used by themselves in blends with polymers having acid-reactive functionality, e.g. to provide blends of copolymer and polyamide. Alterna¬ tively, the acid-functional copolymers of this - invention can be used as additives to compatibilize blends of norbornene dicarboximide polymer and polymers having acid-reactive functionality, e.g. blends of poly(N-methyl norbornene dicarboximide) and nylon-6. The compatibilization of such blends is facilitated in that the.low level of acid functiorrality provides reactive compatibilization with the polyamide and the structural similarity provides miscibility compatibilization with the norbornene dicarboximide polymer. EXAMPLE 1

A polymer of N-methyl norbornene dicarboximide monomer units was prepared by dissolving 4.5 kilograms of N-methyl norbornene dicarboximide in 9.9 kilograms of toluene at 65 °C. After adding 38.5 ml of hexene-1, a molecular weight controlling agent, to the agitated solution, polymerization was effected by adding 114.5 ml of a catalyst solution (0.5 M tungsten hexachloride and 1.5 M diethylacetal of formaldehyde in toluene) and 214 ml of diethyl aluminum chloride. The exothermic metathesis ring- opening polymerization raised the solution temperature to 105 °C in about 20 minutes. After the temperature was reduced to 65 °C stabilizers, e.g. 200 ml of methanol solution of 46 g of an ortho di-t-butyl phenol (Irganox 3125 antioxidant from Ciba-Geigy) and 24 g of tris nonyl phenyl phosphate (Polyguard U.V. stabilizer from Uniroyal) were mixed into the

polymer. The reaction product was chopped, dried, ground and washed with methanol providing 4.4 kg of a poly(N-methyl norbornene dicarboximide) homopolymer. The homopolymer was intimately blended with an equal parts by weight of an EPDM rubber-modified nylon-6,6 (Zytel ST-801 from DuPont) in a Braybender twin screw extruder having barrel and nozzle tempera¬ tures of about 300 °C and screw speed of 80-90 rpm. Samples for analysis were extruded through an Arburg molder at about 300 ^β C and 6900 kPa into molds at about 130 "C. Analytical results of the properties of each of the blend are reported in Table 1.

For characterization, the polymers and blends were injection molded into specimen bars (127 X 12.7 X 3.2 mm) which were conditioned for at least 24 hours at 23 "C and 50% relative humidity. HDTUL was measured according to ASTM D-648; tensile strength, tensile modulus and elongation were measured according to ASTM D-638; flexural strength and flexural modulus were measured according to ASTM D- 790; and notched Izod impact strength was measured according to ASTM D-256.

TABLE 1

*poly(N-methyl norbornene dicarboximide)

EXAMPLE 2 A rubber modified polymer of N-methyl norbornene dicarboximide was prepared in the manner of Example 1, except that a solution of 15 g of Hycar™ nitrile rubber (Goodrich) and 135 g of 1,2-dichloro- ethane was polymerized using 3.4 ml of the 0.5 tungsten hexachloride catalyst solution and 5.6 ml of a 2 M solution of diethyl aluminum chloride in heptane. After the polymerization, 1.5 g of Irganox ■ 1076 hindered phenol antioxidant (Ciba-Geigy) and 0.75 g of Polygard U.V. stabilizer (Uniroyal) were added to the polymer. The polymer was characterized and blended with an equal part of nylon-6. Properties of the polymers and blends are reported in Table 2. TABLE 2

*nitrile rubber-modified poly(N-methyl norbornene dicarboximide)

EXAMPLE 3 The polymerization of N-methyl norbornene dicarboximide was repeated essentially in the manner of Example 1 except that monomer solution contained about 2 percent norbornene dicarboxylic acid anhydride, providing an acid functionalized copoly(N- methyl norbornene dicarboximide/norbornene dicarboxylic anhydride) comprising about 1 percent monomer with acid functionality and having an inherent

viscosity of 0.47, an HDTUL of 160 °C, Flexural strength of 140 MPa and flexural modulus of 3 GPa.

Equal parts of acid anhydride-modified copolymer were blended with equal parts of each of the following polymers: (a) nylon-6,6 (Vydyne 21 from

Monsanto), (b) EPDM rubber-modified nylon-6,6 (Zytel ST-801 from DuPont) and (c) a rubber-modified nylon-6 (65% nylon-6, 292 Kraton G 1652 styrene-butadiene block copolymer and 6% Kraton 1901X maleated styrene- butadiene block copolymer) . The polymers were blended in the manner of Example 1 in a Braybender twin screw extruder; properties of molded samples of the 50/50 blends are reported in Table 3.

TABLE 3 50/50 Blends of Acid Anhydride-modified Copolymer with:

While specific embodiments have been described herein, it should be apparent to those skilled in the art that various modifications thereof can be made without departing from the true spirit and scope of the invention. Accordingly, it is intended that the following claims cover all such modifications within the full inventive concept.