Reinforcement promoters for filled thermoplastic polymers

Abstract

A reinforced, filled thermoplastic polymer composition, having increased strength and ductility, contains a reinforcement promoter having at least two reactive olefinic double bonds and a positive promoter index, based on the double bond resonance and polarity, and the promoter adsorptivity.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is related to copending patent applications Ser. No. 461,088 cause a concomitant reduction in the strength of the composite. In summary, the effect of the reinforcement promoter of the present invention may not merely be to increase the adhesion between the filler particles and the thermoplastic polymer matrix, nor may it be that the promoter is solely a "graded seal", i.e., an interphase layer having a modulus intermediate between that of the filler and the polymer. In contrast, it may be that the desired effect is a much more complex morphological change in the polymer interphase layer which must become both stronger and tougher than the original matrix polymer while at the same time exhibit adhesion both to the polar surface of the filler particles and to the relatively unmodified, non-polar bulk thermoplastic polymer matrix phase.

There are certain similarities between the behavior of carbon black and silica in many elastomers and the behavior of mineral fillers in polyolefins in the presence of the reinforcement promoters of the present invention. For a review of filler reinforcement phenomena in elastomers, see G. Kraus (editor), Reinforcement of Elastomers, New York, 1965 (Interscience), particularly Chapter 8 by W. F. Watson entitled "Chemical Interactions of Fillers and Rubbers During Cold Milling". It has been long known that both cold and hot milling of carbon or silica filled rubbers lead to the formation of so-called "bound rubber", such that even in the uncured state, the filler becomes irreversibly bound to a portion of the rubber which swells but does no longer dissolve in a typical rubber solvent. Although the detailed relationship between the formation of "bound rubber" and the extraordinary reinforcement effect of carbon black and silica in rubber is still not fully understood, there is a general agreement that the two phenomena are related. Such "bound" polymer has been observed on the filler after solvent extraction of polyolefins milled with mineral fillers in the presence of the reinforcement promoters of the present invention, suggesting that the utilization of the reinforcement promoters which satisfy the Equation (A) may enable a unique achievement in the reinforcement of general purpose, thermoplastic polyolefins with heretofore non-reinforcing mineral fillers.

EXAMPLES

The following examples illustrate the effect of the reinforcement promoters of the present invention, as compared with various control chemicals. Unless otherwise indicated, the procedure for making the treated, filled thermoplastic polymer compositions was as follows.

The filler pretreatment procedure consisted of dissolving about 10 g of reinforcement promoter in enouth solvent, e.g., acetone, to dissolve the promoter, but less than the amount of solvent which would produce a paste with the wetted filler. The promoter solution was then added to 500 g of filler, blended mechanically and air dried overnight.

The pretreated filler was compounded with 250 g of thermoplastic polymer on a 6" by 12" 2-roll mill at 180°C by adding 250 g of pretreated filler incrementally to the fluxed polymer. Mixing was continued using thorough compounding procedures. A sheet of the treated, filled polymer was then cut and rolled into a cylindrical bar, i.e., "pig", and then passed end-wise through the compounding mill about ten times for a total mixing time for of ten minutes after all the filler has had been added. The product composition was then sheeted off the mill, allowed to cool to room temperature and granulated in a granulator.

The following testing procedures were used for each product composition. The granulated product composition was injection molded at a melt temperature of 215°C using a 38 cm³ capacity, 30 ton reciprocating screw-injection machine with a mold providing an ASTM dog bone test bar with dimensions of 2" by 1/2" by 1/8" for testing tensile properties, and a rectangular bar with dimensions of 5" by 1/2" by 1/8" for testing flexural properties. The following tests were used for each product composite:

______________________________________
Property Tested    ASTM Test Designation
______________________________________
Tensile Strength
Tensile Modulus
Elongation at Yield    D638-76
Elongation at Break
Flexural Strength
D790-71
Flexural Modulus
Izod Impact Strength   D256-73
Heat Distortion Temperature
D648-72
______________________________________

During the tension and flexural tests a cross-head speed of 0.2" per minute was utilized.

The chemical designations used in the examples are defined as follows:

______________________________________
Designation
Description
______________________________________
AAM      Acrylamide
ABA      Abietic acid
ATH      Aluminum trihydrate having an average
particle size of 0.3 to 1.0 μm and a
surface area of about 6 to 15 m2 g.
CaCO3 I
Calcium carbonate consisting of a finely
ground limestone having 93 to 96 percent
calcium carbonate in the form of a calcite
having an average particle size of 3.5 μm.
Clay I   An unmodified hard clay consisting of a
hydrated kaolin with a mean particle size
of 0.3 μm and a B.E.T. surface area of 20
to 24 m2 g.
CSTA     Calcium stearate
DGDA     Diethylene glycol diacrylate
HDPE I   A high-density polyethylene having a
density of 0.959 g/cc and a melt index of
0.7.
HDPE II  A high-density polyethylene having a
density of 0.948 g/cc and a melt index of
0.15.
GMA      Glycerol monoacrylate
ISTA     Isostearic acid
ITIT     Isopropyl tri-isostearyl titanate
MADMA    Maleamic acid derivatives of methylene-aniline
oligomers
MAH      Maleic anhydride
MTA      Melamine triacrylate
PCLTA    Polycaprolactone triacrylate
PEG      Polyethylene glycol
PETA     Pentaerythritol triacrylate
PP I     A pre-stabilized polypropylene homopolymer
having a density of 0.905 and a melt
flow of 5∅
PP II    An unstabilized polypropylene homopolymer
having a density of 0.905 g/cc and a melt
flow of 2∅
TAC      Triallyl cyanurate
TADAP    N,N--Tetraacryloyl 1,6-diaminopyridine
TAHT     Triacryloyl hexahydro-s-triazine
Talc I   A natural, asbestos free, magnesium
silicate containing 98 percent talc with a
mean particle size of 1.5 μm and a B.E.T.
surface area of 17 m2 /g.
TAM      Triallyl mellitoate
TATZTO   Triallyl-s-triazine-2,4,6-(1H,3H,5H)
trione
TETA     Triethylene tetramine
TTA      Trimethylolpropane triacrylate
TTM      Trimethylolpropane trimaleate
TTP      Trimethylolpropane tripropionate
______________________________________

EXAMPLE 1

Treated, filled thermoplastic polymer composition containing about 50 weight percent HDPE I, as thermoplastic polymer, about 49 weight percent ATH as filler and about 1.0 weight percent reinforcement promoter, or other control treating chemical, were prepared and tested using the procedures described above. The ATH filler was pretreated with the chemicals listed in Table 1 with the following results.

TABLE 1
______________________________________
(ATH/HDPE I)
Treating                                Izod
Agent                                   Impact
Type            Tensile  Tensile
Elongation
Strength
(Table I,
Treating Strength Modulus
at Break
(ft-lbs/
II or III)
Agent    (psi)    (ksi)  (%)     in.)
______________________________________
--     None     3,416    269    4.4     1.7
I      TTA      5,606    338    16.3    2.2
I      TTM      5,080    336    15.8    2.7
I      PETA     5,180    311    35.0    5.7
II     DGDA     3,710    247    12.6    1.5
II     GMA      3,610    247    10.0    1.4
II     AAM      3,710    276    8.1     0.9
III    ITIT     2,930    180    27.0    0.8
III    PEG      3,300    217    6.8     2.6
III    TTP      3,300    243    6.5     2.3
______________________________________

The samples treated with reinforcement promoter compounds listed in Table I show an increase in tensile strength of 50-65 percent; a noticeable increase in stiffness; a four to eight fold increase in elongation; as well as a 30 to 330 percent increase in Izod impact strength. In contrast, the chemicals selected from Table II produce only very minor improvements in tensile strength, with little or no increases in tensile modulus some increases in elongation and actual decreases in Izod impact strength. The Table III chemicals significantly reduce both tensile strength and modulus while obtaining improvements in elongation or Izod impact strength.

EXAMPLE 2

The following samples were prepared and tested using the same procedures as in Example 1 except that CaCO₃ I was used as filler in place of the ATH in Example 1.

TABLE 2
__________________________________________________________________________
(CaCO3 I/HDPE I)
Treating                  Izod
Agent                     Impact
Type      Tensile
Tensile
Elongation
Strength
(Table I,
Treating
Strength
Modulus
at Break
(ft-lbs/
II or III)
Agent
(psi)
(ksi)
(%)   in.)
__________________________________________________________________________
--   None 2,900
215-248
23-63 0.5
I    TTA  5,420
296  25    1.9
II   AAM  3,070
254  25    0.6
III  ITIT 2,040
150  33    1.7
__________________________________________________________________________

The results illustrate, for a CaCO₃ /HDPE filled polymer, that the reinforcement promoter performance is important in simultaneously increasing both tensile and impact strength.

EXAMPLE 3

The following samples were prepared and tested as described in Example 1 except that the Clay I was used as the filler in place of the ATH in Example 1.

TABLE 3
______________________________________
(Clay I/HDPE I)
Treating A-               Tensile
Elonga-
Izod
gent Type        Tensile  Mod-  tion   Impact
(Table A,
Treating Strength ulus  at Break
Strength
II or III)
Agent    (psi)    (ksi) (%)    (ft-lbs/in.)
______________________________________
--      None     3,610    256   3.5    0.6
I       TTA      5,080    372   10.6   1.8
I       PCLTA    4,600    358   10.0   1.9
II      MAH      3,970    293   4.4    0.6
III     ISTA     3,520    281   3.2    1.1
______________________________________

The results show that for a Clay I/HDPE I filled polymer, the n-value in the structural formula is important for reinforcement promoter performance.

EXAMPLE 4

Additional ATH-filled HDPE composites were prepared and tested as in Example 1, with the following results.

TABLE 4
______________________________________
(ATH/HDPE I)
Treating                  Tensile
Elonga-
Izod
Agent Type
Treat-  Tensile  Mod-  tion   Impact
(Table I,
ing     Strength ulus  at Break
Strength
II or III)
agent   (psi)    (ksi) (%)    (ft-lbs/in.)
______________________________________
--       None    3,416    269   4.4    1.7
I        TAHT    4,340    290   66.0   4.5
I        PBM     5,140    314   46.0   4.6
II       TAC     3,810    251   3.4    1.6
II       TAM     3,760    221   5.2    N/A*
III      CSTA    3,340    286   68.0   2.9
______________________________________
*N/A -- data not available

These results, along with the data in Tables I, II and III for Q, e and n-values, show that the presence of more than one ethylene unsaturation in itself is not sufficient to establish effective reinforcement promoter performance. Instead, both the Q and e-values should be sufficiently favorable to satisfy the requirement for having a positive promoter index value. These samples show that high Q-values and positive e-values are important for simultaneously achieving high tensile properties as well as high elongation and impact properties.

EXAMPLE 5

The following treated CaCO₃ I/HDPE I samples were prepared and tested as were the samples in Example 2.

TABLE 5
__________________________________________________________________________
(CaCO3 I/HDPE I)
Izod Impact
Treating Agent Type
Treating
Tensile
Tensile
Elongation at
Strength
(Table I, II or III)
Agent Strength (psi)
Modulus (ksi)
Break (%)
(ft-lbs/in.)
__________________________________________________________________________
--         None  2,900  215-248
23-63  0.5
I          TAHT  4,330  265    23     2.5
I          PBM   4,570  275    65     2.6
I          MADMA 4,290  279    88     2.4
II         TAC   3,900  252    22     0.7
__________________________________________________________________________

These samples for treated CaCO₃ I/HDPE I filled polymers show that, as with the treated ATH/HDPE filled polymers in Example 4, multiple ethylenic unsaturation alone in chemicals such as TAC without favorable Q and e-values is insufficient to provide effective reinforcement promotion when compared with the properties of filled polymers treated with chemicals like those listed in Table I.

EXAMPLE 6

The following Clay I-filled HDPE I compositions were prepared and tested as in EXAMPLE 3.

TABLE 6
__________________________________________________________________________
(Clay I/HDPE I)
Izod Impact
Treating Agent Type
Treating
Tensile
Tensile
Elongation at
Strength
(Table I, II or III)
Agent Strength (psi)
Modulus (ksi)
Break (%)
(ft-lbs/in.)
__________________________________________________________________________
--         None  3,610  256    3.5    0.6
I          TADAP 4,650  375    9.4    1.6
I          TAHT  5,060  340    28.0   3.6
II         TATZTO
4,050  336    3.6    0.6
__________________________________________________________________________

The results show, as with Examples 4 and 5, that favorable Q and e-values are necessary as well in clay filled HDPE composition to attain superior reinforcement promoter performance.

EXAMPLE 7

The following treated, ATH-filled polypropylene compositions were prepared and tested as in EXAMPLE 1. In the first three samples a conventional antioxidant stabilized polypropylene, designated PP I, was utilized. In the last four samples an antioxidant-free polypropylene, designated PP II, was utilized.

TABLE 7
______________________________________
(ATH/PP)
Treating A-               Tensile
Elonga-
Izod
gent Type        Tensile  Mod-  tion   Impact
(Table I,
Treating Strength ulus  at Break
Strength
II or III)
Agent    (psi)    (ksi) (%)    (ft-lbs/in.)
______________________________________
Part A - With Antioxidant, PP I
--      None     3,330    325   2.2    0.3
I       TTA      3,530    316   1.4    0.5
I       PETA     3,330    260   2.7    0.5
Part B - Without Antioxidant, PP II
--      None     3,770    337   1.5    0.3
I       TTA      5,150    357   6.2    0.8
I       PETA     5,050    365   10.0   0.9
II      DGDA     3,800    344   2.5    0.4
______________________________________

The results show that antioxidants contained in commercial grade polyolefins can inhibit the reinforcement promotion action of the promoters. A comparison of the data between Parts A and B reveals that TTA and PTA have little or no beneficial effects in a highly stabilized PP but produce substantial improvements in both tensile, elongation and impact properties in antioxidant-free PP. In general, therefore, and especially in a less thermally stable polyolefin such as polypropylene, any desired antioxidant addition should occur after the mechano-chemical effects of the reinforcement promoter grafting to the matrix resin have had an opportunity to take place.

EXAMPLE 8

A treated, filled thermoplastic polymer composition of about 1.5 weight percent TTA, about 58.5 weight percent ATH and about 40 weight percent HDPE I, was prepared and tested as in Example 1 yielding the following results:

TABLE 8A
______________________________________
(ATH/HDPE I)
Tensile  Tensile    Elongation
Izod Impact
Strength Modulus    at Break  Strength
(psi)    (ksi)      (%)       (ft-lbs/in.)
______________________________________
5,110    391        25        4.5
______________________________________

The mechanical properties of the composition are surprisingly good considering the high ATH loading. No reference data could be obtained since the untreated control sample was too dry and stiff to achieve compounding.

A high ATH-loading is desirable if the flame retardent properties of ATH are to be fully utilized. The effect of ATH-concentration on the oxygen index and UL-94 flammability ratings is described in an article by B. L. Glazar, E. G. Howard, and J. W. Collette entitled, "The Flammability Characteristics of Highly Mineral Filled Ultrahigh Molecular Weight Polyethylene Composites", in the Journal of Fire and Flammability, Vol. 9, October 1978, at pages 430-444, in which it is reported that the effect of ATH on flame retardancy increases steeply above 50 weight percent ATH. Using the previously referred to technique, by Housslein and Fallick, for directly polymerizing ethylene on filler surface, polyethylenes were prepared with ATH contents up to 80 weight percent, much higher than has been feasible using conventional compounding of ATH into polylethylene at molecular weight ranges suitable for normal thermoplastic processing.

The following results illustrate the UL-94 flammability test data for the ATH filled HDPE composition produced as described above, as compared with unfilled HDPE I controls.

TABLE 8B
______________________________________
(ATH/HDPE I Flame Ratings)
Sample
Thickness ATH        Limiting    UL-94
(Inches)  (wt. %)    Oxygen Index1
Rating2
______________________________________
1/8       0          18          NR
1/8       60         26          VI/VO
1/4       0          18          NR
1/4       60         26          VO
______________________________________
1 Lists the percent of oxygen required to sustain combustion.
2 Using a vertical flame test from Underwriters Laboratories with th
following designations:
NR -- not rated by test since sample continues to burn
VI  less than 25 seconds of burning with no drip
VO  less than 5 seconds of burning with no drip.

The sample represents a successful attempt at compounding a heat formable, highly flame-retarded polyolefin with excellent mechanical properties which is free of noxious and corrosive combustion gases resulting from halogen-containing, flame-retardent additives.

EXAMPLE 9

As shown in previous examples, TAHT is a reinforcement promoter which is highly effective for a broad range of filled resin compositions. Unfortunately, TAHT is a crystalline solid under normal operating conditions and has low solubility in organic solvents or other compounding additives. To assure uniform treatment of the fillers it may be advantageous for ease of compounding to utilize a more soluble reinforcement promoter than pure TAHT. To accomplish this, several mixed structure hexahydro-s-triazines were prepared from mixtures of acrylonitrile and methacrylonitrile using the synthetic procedure previously used to make TAHT. This procedure involves reacting a molar amount of trioxane equivalent to the sum of the number of moles of acrylonitrile and methacrylonitrile, in hexane solvent using a catalytic amount of sulfuric acid/acetic anhydride mixture. The resulting mixed structures have depressed melting point properties and improved solubility as compared with TAHT. Treated, filled polymer compositions containing about 1.0 weight percent of these triazines, about 49 weight percent Clay I, and about 50 weight percent HDPE I exhibited the following properties. The mole fraction of acrylonitrile refers to the ratio of moles of acrylonitrile to the total moles of acrylonitrile and methacrylonitrile in the reactant mixture.

TABLE 9
______________________________________
(Clay I/HDPE I)
Tensile  Tensile  Elongation
Izod Impact
Mole Fraction
Strength Modulus  at Break
Strength
of Acrylonitrile
(psi)    (ksi)    (%)     (ft-lbs/in.)
______________________________________
No treatment
3,610    292      4       0.6
1.00 (TAHT)
5,040    354      40      3.4
0.80      4,900    352      46      3.5
0.75      4,870    353      38      3.6
0.67      4,700    338      50      2.8
______________________________________

The results indicate that the use of more soluble mixed triazines, as compared with pure TAHT, produces little or no reduction in the reinforcement promotion effect of pure TAHT.

EXAMPLE 10

This example illustrates that improvement in the stiffness, impact strength and burst strength can be achieved simultaneously in extruded, high density polyethylene pipe when using low-cost hydrous clay as the filler and TAHT as the reinforcement promoter. Hydrous clay is a non-reinforcing filler in polyolefin when used alone.

The composition was prepared by charging 50 lbs. of Clay I to a Henschel mixer. The mixer was operated at low speed initially while a solution containing 0.500 lbs. of TAHT in 2.5 l of dichloromethane was slowly added to assure uniform distribution. An exhaust fan was then connected and the mixer was turned to high-speed operation while the temperature of the mixture was raised from ambient to 100°C After five minutes, the mixing speed was reduced to low-speed operation with mixing and drying being continued for another 10 minutes. 25 lbs. of the resulting TAHT-treated clay was then blended with 75 lbs. of HDPE II resin powder in a rotating drum for 10 minutes. The blend was then fed to a twin-screw, compounding extruder with temperatures of the rear of the barrel at about 193°C, and with the middle and front barrel at about 215° C. The multi-strand die was kept at about 215°C The treated, filled polymer composition was extruded in strands which were diced-in-line to standard 1/8 " by 1/8" size pellets.

These pellets were then extruded into nominal 1" diameter pipe using a Davis-Standard extruder having a 21/2" barrel diameter and a 24 to 1 fluted mixing screw ratio, under the following operating conditions:

______________________________________
Barrel Temperatures
Zone 1                205°C
Zone 2                210°C
Zone 3                207°C
Zone 4                210°C
Zone 5                215°C
Screen Pack 20/60 mesh
Die Temperature       217°C
Stock Temperature     225°C
Screw Speed           32 rpm
Throughput Rate       79 lbs./hr.
______________________________________

The resulting pipe had a 1.8" O.D. with a wall thickness of 0.0074" having a smooth surface inside and outside. No gels, die plate-out, smoking, or odor problems were encountered during the extrusion. The resulting pipe was tested as is for and for burst strength using compression molded plaques made from granulated extrudate for the other properties, and compared with unfilled HDPE II pipe with the following results:

TABLE 10
______________________________________
(Clay I/HDPE II Pipe)
Test Compositions
Unfilled
Filled
(wt. %)
(wt. %)
______________________________________
Composition
HDPE II             100      74.75
Clay I              --       25.00
TAHT                --       0.25
Properties
Tensile Modulus, ksi
120      170
Izod Impact Strength, ft-lbs/in.
1.9      3.9
Yield Strength, psi 3270     4000
Instant Burst Strength, psi
3500     4050
Long Term Time to Burst, hrs
36       594
(at 1975 psi Hoop Stress)
______________________________________

The results show that using a TAHT reinforcement promoter enables improvements in both stiffness and toughness as well as burst strength to be obtained for treated, clay-filled HDPE in contrast to unfilled HDPE. Untreated, clay-filled HDPE exhibits a reduction in impact and burst strength as compared with unfilled HDPE.

EXAMPLE 11

The following talc-filled HDPE I compositions were prepared and tested as in Example 1.

TABLE 11
______________________________________
(Talc I/HDPE I)
Treating A-                     Elonga-
Izod
gent Type
Treat-  Tensile  Tensile
tion   Impact
(Table I,
ing     Strength Modulus
at Break
Strength
II or III)
Agent   (psi)    (ksi)  (%)    (ft-lbs/in.)
______________________________________
--      None    4,160    339    4.1    1.6
I       MTA     5,090    401    6.6    2.5
II      ABA     4,450    378    3.3    1.0
III     ISTA    4,170    312    4.1    1.2
______________________________________

The results show that talc, which is a naturally hydrophobic mineral filler traditionally unresponsive towards many traditional coupling agents, responds with significant improvements in all the tested properties when treated with a reinforcement promoter, MTA, within the present invention. In contrast, other treating agents, such as ABA, cause only moderate improvements in tensile properties at an expense in ductility and toughness.

EXAMPLE 12

In this example, two non-reinforcement promoters, MAH and TETA, were reacted in situ on a calcium carbonate filler surface. The resulting compound, however, which is considered to be a maleamic acid adduct of TETA, meets the criteria for being a reinforcement promoter within the present invention, having values for n of 3 to 4, for Q of about 1.2, for e of about 1.5, and for R_f ° of less than or equal to about 0.01.

The treatment procedure involves first dissolving MAH in diethyl ether, mechanically stirring the solution into calcium carbonate powder and allowing the mixture to dry overnight at room temperature. TETA is dissolved in dichloromethane, stirred into the MAH-treated CaCO₃ powder mixture and then allowed to dry overnight at room temperature. The total concentration of MAH/TETA was maintained at 2 weight percent of the CaCO₃ I filler while the ratio between the MAH an TETA was varied as indicated in Table 12. Compounding and testing was done as in Example 1.

TABLE 12
______________________________________
(CaCO3 I/HDPE I)
MAH   TETA    Tensile  Tensile
Elongation
Izod Impact
(wt.  (wt.    Strength Modulus
at Break
Strength
%)    %)      (psi)    (ksi)  (%)     (ft-lbs/in.)
______________________________________
0.00  0.00    2,980    258    26      0.7
0.80  1.20    3,320    282    36      0.6
1.15  0.85    4,200    281    52      1.3
1.34  0.66    4,360    280    88      3.6
1.46  0.54    4,410    275    59      3.7
2.00  0.00    3,820    261    21      0.8
______________________________________

The mixture producing the best results occurs at a MAH:TETA mole-ratio of about 3:1, while the mechanical properties are lower at both low mole-ratios of MAH to TETA and for MAH alone. These results clearly demonstrate that although TETA and MAH by themselves are not reinforcement promoters, their reaction products are very effective reinforcement promoters. The reinforcement promoters of the present invention therefore include those chemicals which may be formed in situ during the treatment of the filler or during compounding, using additives which by themselves are not within the definition of reinforcement promoters within the present invention since they do not satisfy Equation (A), as long as the reaction products satisfy the structure and parametric equations characterizing the claimed invention.

Claims

1. A polymer composition substantially free of a free radical initiator or its residue comprising a thermoplastic polymer, selected from the groups consisting of normally of solid hydrocarbon polymers, polyamides and polyvinyl chlorides including the copolymers of the latter with vinyl acetate and an inorganic filler having an average particle size <100 μm wherein the improvement comprises providing about 0.1 to 5 weight % based on the weight of the total composition of a reinforcement promoter having at least two reactive olefinic double bonds, said promoter being characterized by having a promoter index, P, being greater than zero, which is defined by the formula:

P=n(n--1)Q(e+2)(1--2R°_f)--2.5

wherein n is the number of olefinic double bonds in the promoter, having values ≧ a value of at least 2, Q and e are the Alfrey-Price resonance and polarity parameters, respectively, of at least one of the olefinic double bonds in the compound, wherein Q≧2>0 and e≧2 but <4,>0 and R°_f, having values≧0 to ≦ a value <nd∅5, is the relative flow ratio of the promoter measured by thin layer chromatography on a neutral silica gel using xylene as the eluant and di-n-butyl fumarate as the standard.

2. The composition of claim 1 wherein the thermoplastic polymer is a hydrocarbon homopolymer or copolymer.

3. The composition of claim 2 wherein the hydrocarbon polymer is a polyolefin homopolymer or copolymer, or a natural or synthetic rubber.

4. The composition of claim 1 wherein the reinforcement promoter has the structure: ##STR18## wherein R¹ is an organic group free of olefinic or acetylenic unsaturation having a valence of n; R², and R³ and R⁴ are hydrogen, carboxy or monovalent organic groups free of olefinic or acetylenic unsaturation; X is: ##STR19## m has a value of 0 or 1; and n has a value of at least two.

5. The composition of claim 4 wherein the reinforcement promoter has an R' R¹ or X group, for when m is 1 or 0, respectively, which contains a double or triple bond which is in conjugation with the olefinic bond and which is electron withdrawing.

6. The composition of claim 1 wherein the reinforcement promoter is a condensation product of an acrylic or maleamic acid with an aliphatic, aromatic or heterocyclic polyol; or an acrylamide, maleimide or maleamic acid of an aliphatic, aromatic or heterocyclic polyamine.

7. The composition of claim 6 wherein the reinforcement promoter compound is an imide, maleate, acrylate, or acryloyl heterocyclic compound.

8. The composition of claim 7 wherein the reinforcement promoter is epoxidized linseed oil/acrylate, 1,3,5-triacryloylhexahydro-s-triazine, melamine triacrylate or maleamic acid derivatives of methylene-aniline oligomers.

9. The composition of claim 1 wherein the inorganic filler is aluminum trihydrate, clay, talc or calcium carbonate.

10. The composition of claim 1 wherein the reinforcement promoter is present in an amount of from about 0.1 to 5.0 weight percent, the filler is from about 10 to 90 weight percent and the thermoplastic polymer is from about 10 to 90 weight percent, based on the total weight of promoter, filler and polymer in the composition.

11. A reinforced polymer composition substantially free of a free radical initiator or its residue comprising a thermoplastic polymer selected from the group consisting of normally solid hydrocarbon polymers, polyamides and polyvinyl chlorides including the copolymers of the latter with vinyl acetate and an inorganic filler having an average particle size <100 μm wherein the improvement comprises providing about 0.1 to 5 weight % based on the weight of the total composition of a reinforcement promoter at the boundary between the filler and polymer, for increasing the strength and ductility of the filled thermoplastic polymer, wherein the promoter has at least two reactive olefinic double bonds, and wherein said promoter is characterized by having a promoter index, P, being greater than zero, and which is defined by the formula:

P=n(n--1)Q(e+2) (1-2R_f °)--2.5

wherein n is the number of olefinic bonds in the promoter, having a value of at least 2, Q and e are the Alfrey-Price resonance and polarity parameters, respectively, for at least one of the olefinic double bonds in the promoter, wherein Q>0 and e>0, and R_f °, having a value <0.5, is the relative flow ratio of the promoter measured by thin layer chromatography on a neutral silica gel using xylene as the eluant and di-n-butyl fumarate as the standard.

12. A process for making a reinforced, filled polymeric composition comprising:

(a) admixing a filler having an average particle size <100 μm with a reinforcement promoter having at least two reactive olefinic double bonds, wherein said promoter is characterized by having a promoter index, P, being greater than zero, and which is defined by the formula:

P=n(n-1)Q(e+2)(1-2R_f °)--2.5

wherein n is the number of olefinic double bonds in the promoter, having a value of at least 2, Q and e are the Alfrey-Price resonance and polarity parameters, respectively, of at least one of the olefinic double bonds in the promotor, wherein Q>0 and e>0, and R_f °, having a value <0.5, is the relative flow ratio of the promotor measured by thin layer chromatography on a neutral silica gel using xylene as the eluant and di-n-butyl fumarate as the standard;

(b) compounding the filler and promoter mixture with a thermoplastic polymer selected from the group consisting of normally solid hydrocarbon polymers, polyamides and polyvinyl chlorides including the copolymers of the latter with vinyl acetate for a time sufficient to generate a reinforced, filled thermoplastic polymer having increased strength and ductility;

(c) wherein said admixing and compounding is carried out in the substantial absence of any free radical initiator.

13. The process of claim 12 wherein the filler and promoter are admixed simultaneously to the compounding with the thermoplastic polymer.

14. The process of claim 12 wherein the reinforcement promoter is formed in situ during mixing with the filler or during compounding with the polymer.

15. The use of a reinforcement promoter in a filled thermoplastic polymer, selected from the group consisting of normally solid hydrocarbon polymers, polyamides and polyvinyl chlorides including the copolymers of the latter with vinyl acetate, composition substantially free of a free radical initiator or its residue wherein the improvement comprises providing a reinforcement promoter having at least two reactive olefinic double bonds, said promoter being characterized by having a promoter index, P, being greater than zero, and which is defined by the formula:

P=n(n-1)Q(e+2)(1-2R_f °)--2.5

wherein n is the number of olefinic double bonds in the promoter, having a value of at least 2, Q and e are the Alfrey-Price resonance and polarity parameters, respectively, of at least one of the olefinic double bonds in the promoter, wherein Q>0 and e>0, and R_f °, having a value <0.5, is the relative flow ratio of the promoter measured by thin layer chromatography on a neutral silica gel using xylene as the eluant and di-n-butyl fumarate as the standard.

16. The composition of claim 1 wherein the Alfrey-Price resonance parameter, Q, is ≧0.4. 17. The composition of claim 16 wherein the number of olefinic bonds, n, is at least 3 and the relative flow ratio, R°_f, is <0.05. 18. The composition of claim 11 wherein the Alfrey-Price resonance parameter, Q, is ≧0.4. 19. The composition of claim 18 wherein the number of olefinic bonds, n, is at least 3 and the relative flow ratio, R°_f, is <0.05. 20. The process of claim 12 wherein the Alfrey-Price resonance parameter, Q, is ≧0.4. 21. The process of claim 20 wherein the number of olefinic bonds, n, is at least 3 and the relative flow ratio, R°_f, is <0.05. 22. The process of claim 15 wherein the Alfrey-Price resonance parameter, Q, is ≧0.4. 23. The process of claim 22 wherein the number of olefinic bonds, n, is at least 3 and the relative flow rate, R°_f, is <0.05.