Toughened polymer blends

BACKGROUND OF THE INVENTION 
The present invention relates to toughened blends of syndiotactic 
monovinylidene aromatic and amide polymers. 
Blends of syndiotactic monovinylidene aromatic polymers, e.g. syndiotactic 
polystyrene (SPS) and polyamides, e.g. nylon, are known in the art, having 
excellent impact and heat resistance. Typically, these types of blends are 
toughened using various rubbery polymers. For example, U.S. Pat. No. 
5,395,890 issued to Nakano et al. discloses a resin composition containing 
SPS, nylon and optionally a rubbery block polymer. Additionally, U.S. Pat. 
No. 5,219,940 discloses SPS and polyamide blends, optionally containing 
block or grafted rubbers. U.S. Pat. No. 5,270,353 discloses blends of SPS 
with nylon toughened with block and maleated block copolymers. However, 
block copolymer rubbers are expensive and add significant cost to the 
blends. 
Therefore, there remains a need to obtain more cost effective toughened 
SPS/polyamide blends while maintaining good impact and heat resistant 
properties. 
SUMMARY OF THE INVENTION 
The present invention is a polymer blend comprising: 
a) a syndiotactic monovinylidene aromatic polymer, 
b) a polyamide, 
c) a compatibilizing polymer for a) and b), 
d) a rubbery polyolefin impact modifier, optionally extended with oil, 
e) a domain forming rubbery polymer, 
f) a polar group functionalized rubbery polyolefin, and 
g) optionally, a compatibilizing polymer for a) and d). 
These blends are more economical than those of the prior art, using 
polyolefin elastomers as toughening agents, and can be used in markets 
where high heat resistance is required such as in automotive applications 
and in applications where nylon alone has been typically used. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In one embodiment, the present invention is a toughened blend of a 
syndiotactic monovinylidene aromatic polymer and a polyamide. 
As used herein, the term "syndiotactic" refers to polymers having a 
stereoregular structure of greater than 90 percent syndiotactic, 
preferably greater than 95 percent syndiotactic, of a racemic triad as 
determined by .sup.13 C nuclear magnetic resonance spectroscopy. 
Monovinylidene aromatic polymers are homopolymers and copolymers of vinyl 
aromatic monomers, that is, monomers whose chemical structure possess both 
an unsaturated moiety and an aromatic moiety. The preferred vinyl aromatic 
monomers have the formula 
EQU H.sub.2 C.dbd.CR--Ar; 
wherein R is hydrogen or an alkyl group having from 1 to 4 carbon atoms, 
and Ar is an aromatic radical of from 6 to 10 carbon atoms. Examples of 
such vinyl aromatic monomers are styrene, alpha-methylstyrene, 
ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyl 
toluene, para-t-butylstyrene, vinyl naphthalene, divinylbenzene and the 
like. Syndiotactic polystyrene is the currently preferred syndiotactic 
monovinylidene aromatic polymer. Typical polymerization processes for 
producing syndiotactic monovinylidene aromatic polymers are well known in 
the art and are described in U.S. Pat. Nos. 4,680,353, 5,066,741, 
5,206,197 and 5,294,685, which are incorporated herein by reference. 
The Mw of the syndiotactic monovinylidene aromatic polymer used in the 
blend of the present invention is not critical, but is typically from 
200,000 to 450,000. 
The amount of syndiotactic monovinylidene aromatic polymer present in the 
blend of the present invention is typically from 10 to 90 weight percent 
based on the total weight of the blend, preferably from 20 to 80 weight 
percent and more preferably from 30 to 60 weight percent. 
The polyamide of component b) of the blend of the present invention can be 
any thermoplastic polyamide. Typical polyamides include polyamide4; 
polyamide-6; polyamide-4,6; polyamide-6,6; polyamide-3,4; polyamide-1,2; 
polyamide-1,1; polyamide-6,10; polyamide purified from terephthalic acid 
and 4,4' diaminocyclohexylmethane; polyamide purified from azelaic acid, 
adipic acid and 2,2,-bis(p-aminocyclohexyl)propane; polyamide purified 
from adipic acid and methaxylylenediamine; and polyamide purified from 
terephthalic acid and trimethylhexamethylene diamine. 
The Mw of the polyamide is not critical but is typically from 40,000 to 
60,000. 
The amount of polyamide present in the blend of the present invention is 
typically from 10 to 90 weight percent based on the total weight of the 
blend, preferably from 20 to 80 weight percent and more preferably from 30 
to 60 weight percent. 
The syndiotactic monovinylidene aromatic polymer a), and polyamide b) are 
typically present in the blend of the present invention in ratios of from 
5:95 to 95:5 based on only those two components. Preferably in ratios of 
20:80 to 80:20, more preferably 30:70 to 70:30 and most preferably 40:60 
to 60:40. 
Component c) of the present invention is a polymer which acts as a 
compatibilizer for the syndiotactic monovinylidene aromatic polymer and 
the polyamide. This can be any material which has a functionality 
compatible with the monovinylidene aromatic and a functionality compatible 
with the amide functional groups. Typically, the compatibilizer is a 
polyarylene ether having such functionalities. Polyarylene ethers are a 
known class of polymer having been previously described in U.S. Pat. Nos. 
3,306,874, 3,306,875, 3,257,357, and 3,257,358. A preferred polyarylene 
ether is poly(2,6-dimethyl-1,4-phenylene)ether. The polyphenylene ethers 
are normally prepared by an oxidative coupling reaction of the 
corresponding bisphenol compound. Preferred polyarylene ethers are polar 
group functionalized polyarylene ethers, which are a known class of 
compounds prepared by contacting polar group containing reactants with 
polyarylene ethers. The reaction is normally conducted at an elevated 
temperature, preferably in a melt of the polyarylene ether, under 
conditions to obtain homogeneous incorporation of the functionalizing 
reagent. Suitable temperatures are from 150.degree. C. to 300.degree. C. 
Suitable polar groups include the acid anhydrides, acid halides, acid 
amides, sulfones, oxazolines, epoxies, isocyanates, and amino groups. 
Preferred polar group containing reactants are compounds having up to 20 
carbons containing reactive unsaturation, such as ethylenic or aliphatic 
ring unsaturation, along with the desired polar group functionality. 
Particularly preferred polar group containing reactants are dicarboxylic 
acid anhydrides, most preferably maleic anhydride. Typically the amount of 
polar group functionalizing reagent employed is from 0.01 percent to 20 
percent, preferably from 0.5 to 15 percent, most preferably from 1 to 10 
percent by weight based on the weight of polyarylene ether. The reaction 
may be conducted in the presence of a free radical generator such as an 
organic peroxide or hydroperoxide agent if desired. Preparation of polar 
group functionalized polyarylene ethers have been previously described in 
U.S. Pat. Nos. 3,375,228, 4,771,096 and 4,654,405. 
The amount of polyarylene ether employed in the present resin blend is 
beneficially from 0.1 to 20 weight percent, preferably from 0.2 to 10, 
more preferably from 0.5 to 5 weight percent based on the total blend 
weight. 
In one embodiment of the invention the polar group modified polyarylene 
ether may be in the form of a coating applied to the outer surface of a 
reinforcing agent to impart added compatibility between the reinforcing 
agent and the polymer matrix. The polar group modified polyarylene ether 
so utilized may be in addition to further amounts of polyarylene ether or 
polar group modified polyarylene ether also incorporated in the blend. The 
surface coating is suitably applied to the reinforcing agent by contacting 
the same with a solution or emulsion of the polar group functionalized 
polyarylene ether. Suitable solvents for dissolving the polar group 
functionalized polyarylene ether to form a solution or for use in 
preparing an emulsion of a water-in-oil or oil-in-water type include 
methylene chloride, trichloromethane, trichloro-ethylene and 
trichloroethane. Preferably the concentration of polar group 
functionalized polyarylene ether in the solution or emulsion is from 0.1 
weight percent to 20 weight percent, preferably 0.5 to 5 percent by 
weight. After coating of the reinforcing agent using either a solution or 
emulsion, the liquid vehicle is removed by, for example, evaporation, 
devolatilization or vacuum drying. The resulting surface coating is 
desirably from 0.001 to 10 weight percent of the uncoated reinforcing 
agent weight. 
The blend of the present invention is toughened using two rubbery 
polyolefins, one for each polymer phase of a)(syndiotactic monovinylidene 
aromatic polymer) and b)(polyamide). Component d) is a rubbery polyolefin 
which toughens the syndiotactic vinyl aromatic phase and can be any 
elastomeric polyolefin. 
Elastomeric polyolefins include any polymer comprising one or more 
C.sub.2-20 .alpha.-olefins in polymerized form, having Tg less than 
25.degree. C., preferably less than 0.degree. C. Examples of the types of 
polymers from which the present elastomeric polyolefins are selected 
include homopolymers and copolymers of .alpha.-olefins, such as 
ethylene/propylene, ethylene/1-butene, ethylene/1-hexene or 
ethylene/1-octene copolymers, and terpolymers of ethylene, propylene and a 
comonomer such as hexadiene or ethylidenenorbornene. Grafted derivatives 
of the foregoing rubbery polymers such as polystyrene-, maleic anhydride-, 
polymethylmethacrylate- or styrene/methyl methacrylate copolymer-grafted 
elastomeric polyolefins may also be used. 
The elastomeric polyolefins are preferably softened by incorporation of an 
aliphatic oil to extend the polyolefin phase, making it softer and more 
readily dispersed into the syndiotactic vinyl aromatic polymer phase. The 
extending oils, also referred to as paraffinic/naphthenic oils, are 
usually fractions of refined petroleum products having less than about 30 
percent by weight of aromatics (by clay-gel analysis) and having 
viscosities between about 100 and 500 SSU at 100.degree. F. (38.degree. 
C.). Commercial extending oils include SHELLFLEX.RTM. oils, numbers 310, 
371 and 311 (which is a blend of 310 and 371), available from Shell Oil 
Company or Drakeol.TM., numbers 34 or 35, available from Penreco division 
of Pennzoil Products Company. The amount of extending oil employed varies 
from 0.01 to 35.0 weight percent, preferably from 0.1-25 percent, most 
preferably from 2-25 weight percent based on the weight of the elastomeric 
polyolefin. 
Preferred elastomeric polyolefins for use herein are such polymers that are 
characterized by a narrow molecular weight distribution and a uniform 
branching distribution. Preferred elastomeric polyolefins are linear or 
substantially linear ethylene interpolymers having a density from 0.85 to 
0.93 g/cm.sup.3, a melt index from 0.1 to 5 g/10 min, and a polydispersity 
of from 1.8 to 5. Such polymers are preferably those prepared using a 
Group 4 metal constrained geometry complex by means of a continuous 
solution polymerization process, such as disclosed in U.S. Pat. Nos. 
5,272,236 and 5,278,272, which are hereby incorporated by reference. More 
preferred elastomeric polyolefins have a density of from 0.860 to 0.920 
g/cm.sup.3, more preferably from 0.865 to 0.915 g/cm.sup.3, and especially 
less than or equal to 0.910 g/cm.sup.3. 
The term "interpolymer" as used herein refers to polymers prepared by the 
polymerization of at least two different monomers. The generic term 
interpolymer thus embraces copolymers, usually employed to refer to 
polymers prepared from two different monomers, and polymers prepared from 
more than two different monomers. 
While describing in the present invention a polymer or interpolymer as 
comprising or containing certain monomers, it is meant that such polymer 
or interpolymer comprises or contains polymerized therein units derived 
from such a monomer. For example, if the monomer is ethylene CH.sub.2 
.dbd.CH.sub.2, the derivative of this unit as incorporated in the polymer 
is --CH.sub.2 --CH.sub.2 --. 
Where melt index values are specified in the present application without 
giving measurement conditions, the melt index as defined in ASTM D-1238, 
Condition 190.degree. C./2.16 kg (formerly known as "Condition (E)" and 
also known as I2) is meant. 
The term "substantially linear" ethylene polymer or interpolymer as used 
herein means that, in addition to the short chain branches attributable to 
intentionally added .alpha.-olefin comonomer incorporation in 
interpolymers, the polymer backbone is substituted with an average of 0.01 
to 3 long chain branches/1000 carbons, more preferably from 0.01 long 
chain branches/1000 carbons to 1 long chain branches/1000 carbons, and 
especially from 0.05 Iong chain branches/1000 carbons to 1 long chain 
branches/1000 carbons. 
Long chain branching is defined herein as a chain length of at least 1 
carbon less than the number of carbons in the longest intentionally added 
.alpha.-olefin comonomer, whereas short chain branching is defined herein 
as a chain length of the same number of carbons in the branch formed from 
any intentionally added .alpha.-olefin comonomer after it is incorporated 
into the polymer molecule backbone. For example, an ethylene/1-octene 
substantially linear polymer has backbones substituted with long chain 
branches of at least 7 carbons in length, but it also has short chain 
branches of only 6 carbons in length resulting from polymerization of 
1-octene. 
The presence and extent of long chain branching in ethylene interpolymers 
is determined by gel permeation chromatography coupled with a low angle 
laser light scattering detector (GPC-LALLS) or by gel permeation 
chromatography coupled with a differential viscometer detector (GPC-DV). 
The use of these techniques for long chain branch detection and the 
underlying theories have been well documented in the literature, for 
example in Zimm, G. H. and Stockmayer, W. H., J. Chem. Phys., Vol. 17, p. 
1301 (1949) and Rudin, A., Modern Methods of Polymer Characterization, 
John Wiley & Sons, New York (1991), pp. 103-112. 
A. Willem deGroot and P. Steve Chum, both of The Dow Chemical Company, at 
the Oct. 4, 1994 conference of the Federation of Analytical Chemistry and 
Spectroscopy Society (FACSS) in St. Louis, Mo., U.S.A., presented data 
demonstrating that GPC-DV is a useful technique for quantifying the 
presence of long chain branches in substantially linear ethylene 
interpolymers. In particular, deGroot and Chum found that the level of 
long chain branches in substantially linear ethylene homopolymer samples 
measured using the Zimm-Stockmayer equation correlated well with the level 
of long chain branches measured using .sup.13 C NMR. 
Further, deGroot and Chum found that the presence of octene does not change 
the hydrodynamic volume of the polyethylene samples in solution and, as 
such, one can account for the molecular weight increase attributable to 
octene short chain branches by knowing the mole percent octene in the 
sample. By deconvoluting the contribution to molecular weight increase 
attributable to 1-octene short chain branches, deGroot and Chum showed 
that GPC-DV may be used to quantify the level of long chain branches in 
substantially linear ethylene/1-octene copolymers. 
deGroot and Chum also showed that a plot of Log(12, Melt Index) as a 
function of Log(GPC, Weight Average Molecular Weight) as determined by 
GPC-DV illustrates that the long chain branching aspects (but not the 
branching extent) of substantially linear ethylene polymers are comparable 
to that of high pressure, highly branched low density polyethylene (LDPE) 
and are clearly distinct from ethylene polymers produced using 
Ziegler-type catalysts such as hafnium and vanadium complexes. 
The empirical effect of the presence of long chain branching in the 
substantially linear ethylene/.alpha.-olefin interpolymers used in the 
invention is manifested as enhanced rheological properties which are 
quantified and expressed herein in terms of gas extrusion rheometry (GER) 
results, and/or in terms of melt flow ratio (I10/I2) increase. 
In contrast to the term "substantially linear", the term "linear" means 
that the polymer lacks measurable or demonstrable long chain branches, 
i.e., the polymer is substituted with an average of less than 0.01 long 
branches/1000 carbons. 
Substantially linear ethylene interpolymers as used herein are further 
characterized as having 
(i) a melt flow ratio, I10/I2 .gtoreq.5.63, 
(ii) a molecular weight distribution or polydispersity, Mw/Mn, as 
determined by gel permeation chromatography and defined by the equation: 
(Mw/Mn)=(I10/I2)-4.63, 
(iii) a critical shear stress at the onset of gross melt fracture, as 
determined by gas extrusion rheometry, of greater than 4.times.10.sup.6 
dynes/cm.sup.3, or a gas extrusion rheology such that the critical shear 
rate at onset of surface melt fracture for the substantially linear 
ethylene polymer is at least 50 percent greater than the critical shear 
rate at the onset of surface melt fracture for a linear ethylene polymer, 
wherein the substantially linear ethylene polymer and the linear ethylene 
polymer comprise the same comonomer or comonomers, the linear ethylene 
polymer has an I2, Mw/Mn and density within 10 percent of the 
substantially linear ethylene polymer and wherein the respective critical 
shear rates of the substantially linear ethylene polymer and the linear 
ethylene polymer are measured at the same melt temperature using a gas 
extrusion rheometer, and 
(iv) a single differential scanning calorimetry, DSC, melting peak between 
-30.degree. C. and 150.degree. C. 
Determination of the critical shear rate and the critical shear stress in 
regards to melt fracture as well as other rheology properties such as the 
"rheological processing index" (PI) is performed using a gas extrusion 
rheometer (GER). The gas extrusion rheometer is described by M. Shida, R. 
N. Shroff and L. V. Cancio in Polymer Engineering Science, Vol. 17, No. 
11, p. 770 (1977), and in Rheometers for Molten Plastics, by John Dealy, 
published by Van Nostrand Reinhold Co. (1982) on pp. 97-99. The processing 
index is measured at a temperature of 190.degree. C., at nitrogen pressure 
of 2500 psig (17 Mpa) using a 0.0296 inch (0.0117 cm) diameter, 20:1 L/D 
die with an entrance angle of 180.degree.. The GER processing index is 
calculated in millipoise units from the following equation: 
EQU PI=2.15.times.10.sup.6 dynes/cm.sup.2 /(1000.times.shear rate), 
where: 2.15.times.10.sup.6 dynes/cm.sup.2 is the shear stress at 2500 psi, 
(17 Mpa) and the shear rate is the shear rate at the wall represented by 
the following equation: 32Q'/(60 sec/min)(0.745)(diameter.times.2.54 
cm/in).sup.3, where Q' is the extrusion rate (g/min), 0.745 is the melt 
density of the polyethylene (g/cm.sup.3), and diameter is the orifice 
diameter of the capillary (inches). 
The PI is the apparent viscosity of a material measured at apparent shear 
stress of 2.15.times.10.sup.6 dyne/cm.sup.2. 
For the substantially linear ethylene polymers described herein, the PI is 
less than or equal to 70 percent of that of a comparative linear olefin 
polymer having an I2 and Mw/Mn each within 10 percent of the substantially 
linear ethylene polymers. 
The rheological behavior of substantially linear ethylene polymers can also 
be characterized by the Dow Rheology Index (DRI), which expresses a 
polymer's "normalized relaxation time as the result of long chain 
branching." (See, S. Lai and G. W. Knight "ANTEC '93 Proceedings, 
INSITE.TM. Technology Polyolefins (ITP)--New Rules in the 
Structure/Rheology Relationship of Ethylene/.alpha.-Olefin Copolymers," 
New Orleans, La., U.S.A., May 1993.) DRI values range from 0, for polymers 
which do not have any measurable long chain branching (for example, 
TAFMER.TM. products available from Mitsui Petrochemical Industries and 
EXACT.TM. products available from Exxon Chemical Company), to 15 and is 
independent of melt index. In general, for low- to medium-pressure 
ethylene polymers (particularly at lower densities), DRI provides improved 
correlations to melt elasticity and high shear flowability relative to 
correlations of the same attempted with melt flow ratios. For the 
substantially linear ethylene polymers useful in this invention, DRI is 
preferably at least 0. 1, and especially at least 0.5, and most especially 
at least 0.8. DRI can be calculated from the equation: 
EQU DRI=3652879.times..tau..sup.o.spsp.1.00649 /(.eta..sup.o-1)/10 
where .tau..sup.o is the characteristic relaxation time of the material and 
.eta..sup.o is the zero shear viscosity of the material. Both .tau..sup.o 
and are the "best fit" values to the Cross equation, that is, 
EQU .eta./.eta..sup.o =1/(1+(.gamma..multidot..tau..sup.o).sup.n) 
where n is the power law index of the material, and .eta. and .gamma. are 
the measured viscosity and shear rate (rad sec.sup.-1), respectively. 
Baseline determination of viscosity and shear rate data are obtained using 
a Rheometric Mechanical Spectrometer (RMS-800) under dynamic sweep mode 
from 0.1 to 100 rad/sec at 190.degree. C. and a Gas Extrusion Rheometer 
(GER) at extrusion pressures from 1000 psi to 5000 psi (6.89 to 34.5 MPa), 
which corresponds to shear stress from 0.086 to 0.43 MPa, using a 0.0754 
mm diameter, 20:1 L/D die at 190.degree. C. Specific material 
determinations can be performed from 140.degree. C. to 190.degree. C. as 
required to accommodate melt index variations. 
An apparent shear stress versus apparent shear rate plot is used to 
identify the melt fracture phenomena. According to Ramamurthy in Journal 
of Rheology, Vol. 30(2), pp. 337-357, 1986, above a certain critical flow 
rate, the observed extrudate irregularities may be broadly classified into 
two main types: surface melt fracture and gross melt fracture. 
Surface melt fracture occurs under apparently steady flow conditions and 
ranges in detail from loss of specular gloss to the more severe form of 
"sharkskin." In this disclosure, the onset of surface melt fracture (OSMF) 
is characterized as the beginning of losing extrudate gloss at which the 
surface roughness of extrudate can only be detected by 40.times. 
magnification. The critical shear rate at onset of surface melt fracture 
for the substantially linear ethylene polymers is at least 50 percent 
greater than the critical shear rate at the onset of surface melt fracture 
of a linear ethylene polymer having about the same 12 and Mw/Mn. 
Gross melt fracture occurs at unsteady flow conditions and ranges in detail 
from regular (alternating rough and smooth or helical) to random 
distortions. The critical shear rate at onset of surface melt fracture 
(OSMF) and onset of gross melt fracture (OGMF) will be used herein based 
on the changes of surface roughness and configurations of the extrudates 
extruded by a GER. 
The substantially linear ethylene polymers used in the invention are also 
characterized by a single DSC melting peak. The single melting peak is 
determined using a differential scanning calorimeter standardized with 
indium and deionized water. The method involves 5 to 7 mg sample sizes, a 
"first heat" to 150.degree. C. which is held for 4 minutes, a cool down at 
10.degree. C./minute to -30.degree. C. which is held for 3 minutes, and 
heated at 10.degree. C./minute to 150.degree. C. for the "second heat." 
The single melting peak is taken from the "second heat" heat flow versus 
temperature curve. Total heat of fusion of the polymer is calculated from 
the area under the curve. 
For polymers having a density of 0.875 g/cm.sup.3 to 0.910 g/cm.sup.3, the 
single melting peak may show, depending on equipment sensitivity, a 
"shoulder" or a "hump" on the low melting side that constitutes less than 
12 percent, typically less than 9 percent, and more typically less than 6 
percent, of the total heat of fusion of the polymer. Such an artifact is 
observable for other homogeneously branched polymers such as EXACT.TM. 
resins (made by Exxon Chemical Company) and is discerned on the basis of 
the slope of the single peak varying monotonically through the melting 
region of the artifact. Such an artifact occurs within 34.degree. C., 
typically within 27.degree. C., and more typically within 20.degree. C., 
of the melting point of the single peak. The heat of fusion attributable 
to an artifact can be separately determined by specific integration of its 
associated area under the heat flow versus temperature curve. 
The term "polydispersity" as used herein is a synonym for the term 
"molecular weight distribution" which is determined as follows: 
The polymer or composition samples are analyzed by gel permeation 
chromatography (GPC) on a Waters 150.degree. C. high temperature 
chromatographic unit equipped with three mixed porosity columns (Polymer 
Laboratories 103, 104, 105, and 106), operating at a system temperature of 
140.degree. C. The solvent is 1,2,4-trichlorobenzene, from which 0.3 
percent by weight solutions of the samples are prepared for injection. The 
flow rate is 1.0 milliliters/minute and the injection size is 200 
microliters. 
The molecular weight determination is deduced by using narrow molecular 
weight distribution polystyrene standards (from Polymer Laboratories) in 
conjunction with their elution volumes. The equivalent polymer molecular 
weights are determined by using appropriate Mark-Houwink coefficients for 
polyethylene and polystyrene (as described by Williams and Word in Journal 
of Polymer Science, Polymer Letters, Vol. 6, p. 621 (1968), to derive the 
following equation: 
EQU M.sub.polyethylene =0.4316(M.sub.polystyrene). 
Weight average molecular weight, Mw, is calculated in the usual manner 
according to the following formula: 
Mw=.SIGMA.i wi.multidot.Mi, where wi and Mi are the weight fraction and 
molecular weight, respectively, of the ith fraction eluting from the GPC 
column. 
The rubbery polyolefin impact modifier d) is typically present in the blend 
of the present invention in amounts from 0.1 to 10 weight percent based on 
the total blend weight, preferably from 0.5 to 7, more preferably from 1 
to 5 weight percent. The rubbery polyolefin impact modifier is typically 
from 2 to 25 weight percent of the syndiotactic monovinylidene aromatic 
polymer phase. 
The syndiotactic monovinylidene aromatic polymer of a) and rubbery 
polyolefin elastomer of d) are typically present in ratios of from 50:50 
to 99:1 based on only those two components. Preferably 80:20 to 99:1, more 
preferably 85:15 to 98:2 and most preferably 90:10 to 97:3. 
Component e) of the present invention comprises one or more domain forming 
rubbery polymers. Such rubbery polymers are suitably chosen in order to 
impart impact absorbing properties to the polymer composition and enhance 
the toughening performance of the rubbery polyolefin elastomer of d). 
Generally, it is desirable to provide a domain forming rubbery polymer 
having extremely high melt viscosity, that is, very low melt flow. Such 
polymers having high melt viscosity are not drawn into extremely thin 
sections by the shear forces of the compounding process, and retain 
greater ability to reform discrete rubber particles more closely 
resembling spherical particles upon discontinuance of shearing forces. 
Additionally, the domain forming rubbery polymer beneficially should 
retain sufficient elastic memory to reform droplets in the melt when 
shearing forces are absent. One beneficial result of the present 
combination appears to be that the domain forming rubbery polymer is 
selected to be compatible with the rubbery polyolefin elastomer into which 
it mostly partitions under processing condition. Within such domain, the 
shearing forces are not as detrimental to rubber domain formation as when 
the domain forming rubbery polymer is incorporated directly into the 
matrix resin. 
Generally, higher molecular weight domain forming rubbery polymers possess 
increased melt viscosity. Accordingly, preferred domain forming rubbery 
polymers are those having Mw from 100,000 to 400,000 Daltons, more 
preferable from 150,000 to 300,000 Daltons, and having Tg less than 
25.degree. C., more preferably less than 0.degree. C. Weight average 
molecular weights recited herein are apparent values based on a 
polystyrene standard, derived from gel permeation chromatography data, and 
not corrected for hydrodynamic volume differences between polystyrene and 
other polymeric components. Low molecular weight block copolymers, that 
is, polymers having molecular weight less than 100,000 Daltons, have been 
found to possess insufficient melt viscosity to achieve the desired rubber 
droplet formation. Most preferred domain forming rubbery polymers are 
those having a melt flow rate, Condition X (315.degree. C., 5.0 Kg) from 0 
to 0.5 g/10 min. Typical domain forming rubbery polymers include lower 
molecular weight (higher melt index) copolymers of styrene and a rubber 
such as butadiene or isoprene, including styrenelbutadiene/styrene 
triblock copolymers, hydrogenated styrene/butadiene/styrene triblock 
copolymers, styrene/butadiene block copolymers, styrene/isoprene block 
copolymers, or a hydrogenated versions thereof. Preferred block copolymers 
are those containing from 20 to 75 weight percent styrene with the 
remainder comprising butadiene, isoprene or a hydrogenated derivative 
thereof. 
The domain forming rubbery polymer may also act as the compatibilizer 
between the syndiotactic monovinylidene aromatic polymer a) and the 
rubbery polyolefin elastomer d). Typically, such domain forming rubbery 
block copolymers will act as a compatibilizer if the copolymer contains a 
compatibilizing amount of monovinylidene aromatic block. Generally, a 
compatibilizing amount will be at least 30 weight percent, typically at 
least 40 weight percent, preferably at least 50 weight percent, more 
preferably at least 60 weight percent and most preferably at least 70 
weight percent monovinylidene aromatic block. 
Alternatively, a small quantity of a low density polyethylene may also be 
utilized as the domain forming rubbery polymer. Suitable low density 
polyethylene polymers include linear interpolymers of ethylene and at 
least one further .alpha.-olefin, most preferred are homogeneous linear 
interpolymers. Preferred .alpha.-olefins have from 3 to 20 carbon atoms. 
More preferred a-olefins have from 3 to 8 carbon atoms. Exemplary 
comonomers include propene, 1-butene, 1-pentene, 4-methyl- 1-pentene, 
1-hexene, and 1-octene. The low density polyethylene may also contain, in 
addition to the .alpha.-olefin, one or more further comonomers, such as 
diolefins, ethylenically unsaturated carboxylic acids (both mono- and 
difunctional) as well as derivatives of these acids, such as esters and 
anhydrides. Exemplary of such additional comonomers are acrylic acid, 
methacrylic acid, vinyl acetate and maleic anhydride. The low density 
polymers suitable for use in the present compositions can be further 
characterized by their homogeneity and degree of long chain branching. 
Preferred quantities of the domain forming rubbery polymer are from 2 to 
30, most preferably 5 to 25 weight percent based on the weight of the 
rubbery polyolefin elastomer d). The rubbery polyolefin elastomer and 
domain forming rubbery polymer (components d) and e)) are typically 
present in ratios of from 60:40 to 100:0 based on only those two 
components, preferably 70:30 to 95:5 and more preferably 80:20 to 90:10. 
The domain forming rubbery polymer is typically present in amounts of 0.1 
to 5 weight percent based on the total weight of the blend, preferably 
from 0.1 to 3 weight percent, and more preferably from 0.1 to 1 weight 
percent. 
The rubbery polyolefin elastomer of c) and domain forming rubbery polymer 
of e) are typically present in ratios of from 60:40 to 99:1 based on only 
those two components, preferably 70:30 to 95:5, and more preferably 85:15 
to 90:10. 
The polyamide phase b) is toughened by a polar group functionalized 
polyolefin, Component f). Typical functional groups include carboxylic 
acids, carboxylic acid esters, anhydrides, amines, amides, epoxies, 
maleimides and any other functional group which will compatibilize the 
polyolefin with the polyamide phase. The preferred functional groups are 
those groups which can react with the polyamide during melt blending, such 
as amines, epoxies, anhydrides and carboxylic acids. Typically the 
functionalized polyolefin is a maleated polyolefin. Maleated polyolefins 
are known in the art and are typically obtained by grafting maleic 
anhydride onto the polyolefin backbone. The polyolefin may be the same as 
the rubbery polyolefin elastomer used to toughen the syndiotactic 
monovinylidene aromatic phase or different. Typical maleated polyolefins 
include maleated alpha-olefins such as ethylene-octene copolymer, 
ethylene-hexene copolymer, ethylene-heptene copolymer and the like. 
Maleation of the polyolefin may be done by in the melt, in solution, or in 
the solid state, and the process can be either continuous or batch. 
Various free radical initiators, including peroxides and azo compounds may 
be used to facilitate the maleation. All of these processes are well know 
and fully described in the art. Maleating agents can include anhydrides 
such as maleic anhydride, unsaturated dicarboxylic acids such as fumaric 
acid or other agents listed in columns 6-7 of U.S. Pat. No. 5,219,940. 
The amount of polar group functionalized rubbery polyolefin in the blend of 
the present invention is typically from 0.1 to 10 weight percent based on 
the total weight of the blend, preferably from 0.5 to 7, and more 
preferably from 1 to 5 weight percent. The amount of polar group 
functionalized rubbery polyolefin present based on the amount of polyamide 
is typically from 2 to 25 weight percent. 
The polyamide of b) and polar group-functionalized polyolefin elastomer of 
f) are typically present in ratios of from 50:50 to 99:1 based on only 
those two components, preferably 80:20 to 99:1, more preferably 85:15 to 
98:2 and most preferably 90:10 to 97:3. 
Optionally, a compatibilizing polymer, Component g) which acts as a 
compatibilizer for the syndiotactic monovinylidene aromatic polymer a) and 
the rubbery polyolefin elastomer d) is included in the blend of the 
present invention. A compatibilizing polymer is necessary if the domain 
forming rubbery polymer is not a compatibilizing polymer for components a) 
and d). A compatibilizing polymer typically comprises a block copolymer 
such as a lower molecular weight (higher melt index) 
styrene/butadiene/styrene triblock copolymer, a hydrogenated 
styrene/butadiene/styrene triblock copolymer, or a styrenelbutadiene 
diblock copolymer, a styrene/isoprene block copolymer, or a hydrogenated 
derivative thereof. Preferred block copolymers are those containing from 
45 to 75 weight percent styrene with the remainder comprising butadiene, 
isoprene or a hydrogenated derivative thereof. 
A typical ratio of rubbery polyolefin impact modifier of d) to domain 
forming rubbery polymer of e) to compatibilizing agent of g) is 75:15:10 
by weight. 
Nucleators may also be used in the blend of the present invention and are 
compounds capable of reducing the time required for onset of 
crystallization of the syndiotactic monovinylidene aromatic polymer upon 
cooling from the melt. Nucleators provide a greater degree of 
crystallinity in a molding resin and more consistent levels of 
crystallinity under a variety of molding conditions. Higher levels of 
crystallinity are desired in order to achieve increased chemical 
resistance. In addition crystal morphology may be desirably altered. 
Examples of suitable nucleators for use herein are metal salts, especially 
aluminum salts of organic acids or phosphonic acids. Especially preferred 
compounds are aluminum salts of benzoic acid and C.sub.1-10 alkyl 
substituted benzoic acid derivatives. A most highly preferred nucleator is 
aluminum tris(p-tert-butyl)benzoate. The amount of nucleator used should 
be sufficient to cause nucleation and the onset of crystallization in the 
syndiotactic vinylaromatic polymer in a reduced time compared to 
compositions lacking in such nucleator. Preferred amounts are from 0.1 to 
5 weight percent, preferably from 0.1 to 3 weight percent and most 
preferably from 0.2 to 1 weight percent based on the weight of component 
a). 
Additionally a reinforcing agent or filler can be used in the blend of the 
present invention. Suitable reinforcing agents include any mineral, glass, 
ceramic, polymeric or carbon reinforcing agent. Such material may be in 
the shape of fibers having a length to diameter ratio (L/D) of greater 
than 5. Preferred particle diameters are from 0.1 micrometers to 1 
millimeter. Preferred reinforcing agents are glass fibers, glass roving or 
chopped glass fibers having lengths from 0.1 to 10 millimeters and L/D 
from 5 to 100. Suitable fillers include nonpolymeric materials designed to 
reduce the coefficient of linear thermal expansion of the resulting 
material, to provide color or pigment thereto, to reduce the flame 
propagation properties of the composition, or to otherwise modify the 
composition's physical properties. Suitable fillers include mica, talc, 
chalk, titanium dioxide, clay, alumina, silica, glass microspheres, and 
various pigments. Preferred fillers are in the shape of particulates 
having (L/D) less than 5. The amount of reinforcing agent or filler 
employed is preferably from 10 to 50 weight percent, more preferably from 
20 to 40 weight percent based on the total weight of the filled 
composition. 
The reinforcing agent may include a surface coating of a sizing agent or 
similar coating which, among other functions, may promote adhesion between 
the reinforcing agent and the remaining components, especially the matrix, 
of the composition. Suitable sizing agents may contain amine, aminosilane, 
epoxy, and aminophosphine functional groups and contain up to 30 
nonhydrogen atoms. Preferred are aminosilane coupling agents and C.sub.1-4 
alkoxy substituted derivatives thereof, especially 
3-aminopropyltrimethoxysilane. 
Additional additives such as blowing agents, extrusion aids, antioxidants, 
plasticizers, stabilizers, ignition resistant additives, and lubricants, 
may also be included in the composition in amounts up to 10 percent, 
preferably up to 5 percent, by weight, based on final composition weight. 
The blend of the present invention is typically produced by compounding all 
the components in a mixing device such as an extruder. Mechanical mixing 
devices such as extruders, ribbon blenders, solution blending or any other 
suitable device or technique may be utilized. All components (syndiotactic 
monovinylidene aromatic polymer, non-functionalized polyolefin, polar 
functionalized polyolefin, domain forming rubbery polymer, compatibilizing 
polymer, and optional components such as fillers, nucleating agents, 
stabilizers, and the like) can be compounded together in an extruder. The 
oil included in the polyolefin phase can be precompounded into the 
polyolefin elastomer in a separate step or added during the compounding of 
the blend. Compounding should be done above the melting point of the 
syndiotactic monovinylidene aromatic polymer. The syndiotactic polystyrene 
homopolymer has a melting point of 270.degree. C. Excessively high 
temperatures, such as above 320.degree. C., which can cause polymer 
degradation should be avoided. Good mixing should be provided, but 
excessive shear can result in undesirable high temperatures. It is 
remarkable, that in compounding this complicated blend, all components 
migrate to form a structure which imparts desirable properties. 
The compositions of the present invention are prepared by combining the 
respective components under conditions to provide uniform dispersal of the 
ingredients. Alternatively, the polar group functionalized polyarylene 
ether and polar group functionalized polyolefin may be prepared in situ by 
reacting the polar group reactant with the polyphenylene ether and further 
incorporating the molten product directly into the finished blend. 
The following examples are provided to illustrate the present invention. 
The examples are not intended to limit the scope of the present invention 
and they should not be so interpreted. Amounts are in weight parts or 
weight percentages unless otherwise indicated.