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UCC - RESIN-GRADE lM ASBESTOS A WHISKER REINFORCEMENT FOR THERMOPLASTIC RESINS by R. E. Byrne, Jr.
August 25, 1967
BUSINESS CONFIDENTIAL
Union Carbide Corporation
CHEMICALS AND PLASTICS
RESEARCH AND DEVELOPMENT DEPARTMENT
P.O.BOX 579 NIAGARA FALLS. N.Y.
PLAINTIFFS g EXHIBIT
i UC7I540
UCC - RESIN-GRADE 144 ASBESTOS A WHISKER REINFORCEMENT FOR THERMOPLASTIC RESINS by R. E. Byrne, Jr. August 25, 1967
Group Manager - R. G. Woolery Project No. 885-28-2-56 File No. 2
TABLE OF CONTENTS
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INTRODUCTION SUMMARY CONCLUSIONS AND RECOMMENDATIONS . DISCUSSION
General Vinyl Resins Styrene Resins Polyolefins REFERENCES
Page No. 1 1 2
2 h 8 9 12
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Niagara Falls, New York August 25, 1967
UCC - RESIN-GRADE lM ASBESTOS A WHISKER REINFORCEMENT FOR THERMOPLASTIC RESINS
INTRODUCTION
While composite and fiber reinforced structures are thousands of years . old, only in the last two decades has technology become available for synthesizing and optimizing new materials from dissimilar elements to tailor a material for new uses. Growth of this industry, largely in the past 10 years, has resulted in total annual sales in 1966 of over 4 billion dollars.
In fiber reinforced structures, the fiber has the major role of carrying load. The matrix serves to bind the fibers in a fixed spatial arrangement, to transmit and distribute load to the fiber and to protect the fiber, in some cases, from hostile environments.
One of the latest concepts in this field is that of whisker reinforce ment W . W. P. Mulvaney has recently demonstrated the applicability of the theories of whisker technology to the data obtained on asbestos fiber reinforced vinyl resins(2).
This report presents data on the reinforcement of several thermoplastic resins with R-G144 asbestos. While the data are intended to be cursory in nature, they agree, in general, with Mulvaney's conclusions. Work is in progress, both at' Niagara Falls and Bound Brook, on the reinforcement of nylon molding compounds, polysulfone, and rigid vinyl pipe compounds. A report on the properties of rein forced Nylon 6 has recently been issued by W. P. Mulvaney('.
SUMMARY
UCC Resin-Grade iW asbestos (R-Gl^) is hydraulically refined chrysotile mineral with a purity and degree of fiber liberation not previously available. It contains from 2 to 3 times as much fully liberated asbestos (free fibers) as does a conventional asbestos. The chrysotile fibers in R-Gl^ are of smaller diameter and narrower diameter distribution than a Canadian chrysotile. For these reasons, it provides reinforcing effects in synthetic resins which are different from those normally associated with asbestos. R-GlUU may be considered a true reinforcing whisker and should not be considered as a filler.
Data are presented showing the improvement in tensile properties, heat distortion temperature, and, in some cases, impact resistance resulting from the reinforcement of several resins with R-Gl1^. Comparative data show the superiority of R-Gl^ over Canadian chrysotile in a clear vinyl compound. The properties of R-Gl^ reinforced high density polyethylene compare quite favorably with poly propylene .
t
cONOT.USIONS AND RECOMMENDATIONS
From the work presented here, the following conclusions may be drawn:
1) R-G144 is a unique whisker reinforcement for synthetic resins.
2) New classes of polymers, with new levels of performance, can be prepared from R-G144 and standard resins.
3) Resins which have a chemical affinity for chrysotile (hydrated magnesium silicate) benefit most from R-G144 reinforcement.
It is recommended that work be continued to explore R-G144 reinforcement of thermoplastic resins, particularly those with available functional groups, such as polysulfone, polycarbonate, C-4, phenoxy, and acrylics. Chemical modification of R-G144 should be examined as a means of increasing its reinforcing efficiency in less reactive polymers. The reinforcement of epoxy and phenolic resins with high levels of R-G144 should also be investigated.
DISCUSSION
General
UCC Resin-Grade 144 asbestos represents a manufacturing improvement on the natural mineral whisker, chrysotile asbestos. Beicause of increased product purity and the higher content of individual fibrils (whiskers), R-G144 reinforced plastic materials are superior to those obtained with conventional chrysotile products.
Chrysotile is one of a group of six different types of asbestos fibers commercially available. Table I shows the physical characteristics of the six commercially important asbestos minerals. As shown in the table, chrysotile is a tubular, fibrous hydrated magnesium silicate, Mgg(OH)QSii4O^Q, generally believed to be hollow. It makes up about 90% of all asbestos used in the United States, most of which is mined and processed in Canada and is known, consequently, as Canadian chrysotile. (A comprehensive treatment of the mineralogy of chrysotile, its basic fiber properties, and the rheology of aqueous suspensions can be found in a recent report by F. A. Mumpton, et al.)(3;
Canadian chrysotile occurs in low yield (10-15%) as a cross or slip fiber of varying length in serpentine rock. It is refined by crushing and subse quent air separation to remove waste material. It is then graded according to fiber length, from Grade 3 (the longest) to Grade 7. R-G144 is similar in fiber length to Grade 7- As it is normally sold, however, Grade 7 chrysotile asbestos contains only 60% asbestos and 40% serpentine rock dust with the asbestos fibers agglomerated in bundles of varying size. In this respect it differs from R-G144 which is refined hydraulically to contain not less than 99% asbestos and to fully liberate the asbestos fiber to its fundamental particle diameter. R-G144 also contains less than 0.5% magnetite, whereas it may run as high as 3% in a good Grade 7 product.
R-G144 is mined from a massive asbestos deposit near Coalinga, California. The ore yields 40-60% asbestos and is texturally different from most Canadian-type deposits. The favorable mineralogy and hydraulic refining result in R-G144 containing
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a much higher concentration of individual fibrils and fewer fiber bundles than the Canadian chrysotile. As shown in Figure 1, the average diameter of the UCC fibril is about 260 Angstroms and varies over a narrower range than a typical Grade 7 asbestos which averages about 350 Angstroms. The average aspect ratio (length to diameter) of an R-G144 fibril is about 200 which is well above its critical value for optimum reinforcement as shown in Mulvaney's report(2).
The higher purity, larger number of individual fibrils, and smaller average fibril diameter greatly enhance the reinforcing efficiency of R-G144 asbestos. For the same reasons, R-G144 is more efficient for viscosity build-up and thixotropy irj liquid resin systems which has been demonstrated by J. F. Bliss and C. Pitt(3) at
Bound Brook.
Vinyl Resins
R-G144 asbestos, with its strong cationic surface charge, has a natural affinity for and is well wetted by vinyl chloride polymers. Since one of the criteria for good whisker reinforcement is a strong bond between fiber and matrix, it is not surprising that excellent mechanical properties result. In addition, with the proper choice of stabilizers, a compound results which retains excellent see-through even at relatively high (30 phr) asbestos loadings.
Table II shows test data on compression molded samples of VYNS (FVC-FVa copolymer) compounded on a differential speed, two-roll mill. The data show that the optimum combination of strength and rigidity occurs at about 15 phr of R-G144.
TABLE II
Reinforced VYNS*
R-G144, phr
Tensile Strength, psi Tensile Modulus, psi x 10"3
Elongation, %
Izod Impact, ft.-lb./in. Heat Distortion Temp., C.
0 7600
396 2 0.6
63.0
5 8800
430 3 0.5
10 9000
531 3 0.5
69.9
*Formulation
Parts
15 8600
542 4
0.5
20 6700
540 2
25 6000
551 2
VYNS
Temex 5 Advance CH-90
It ABC-18 Stearic acid R-G144
100 1.2
0.5 0.75 1.0
0-25
At this level, neither elongation nor impact strength is adversely affected and a significant improvement in heat distortion temperature (HDT) is apparent. Except for the optimum level, these effects are also reported by Mulvaney^). it should
be noted that the presence of chrysotile in a vinyl compound can result in resin degradation unless suitable stabilizers are added. This degradative effect is more pronounced as the asbestos level increases, but small amounts of Mark C, Advastab CH-90, and similar chelating stabilizers have been found to be effective in over coming degradation at levels up to 50 per cent by weight R Gl44.
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I11 u tjj II
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HISTOGRAM OF A TYPICAL FIBRIL DIAMETER DISTRIBUTI
The properties of R-G144 reinforced rigid vinyls are also influenced by the degree to which the asbestos is dispersed in the system. Dispersion is not difficult, but processing variables can influence the product properties. In some cases, these variables are as important as the critical fiber volume, it has been observed that the critical volume is from about 5 to 15 phr R-G144. Mulvaneyv^),
by mathematical analysis of test results in plasticized PVC samples, has calculated this volume to be from 11-17 per cent.
Table III shows data on Q7TQ (PVC homopolymer) reinforced with R-G144. In general, the effects are the same as those noted with the copolymer except- that optimum loading is somewhat higher. The apparent increase in Izod impact strength is worthy of special note.
Two levels of plasticization with dioctyl phthalate (DOP) are also shown in Table III. The same reinforcing effects are shown in plasticized samples with no significant increase in hardness (Durometer). In the plasticized samples there is no marked decrease in elongations up to 20 phr R-G144.
TABLE III
Reinforced Q7TQ
Gl44, phr
Tens psi
Elong,.,
1o
Mod., psi x 10"3
Izod, ft-lb./in.
H.D.T., C.
0.
5 10 20
8100 7900 8100 8400
127 8
54 4
430 462 467 548
0.52 0.77 1.93 1.10
69.4 70.2
71.9 71.4
- With 20 phr DOR -
0
4250
172
5
4?00
167
10
5000
182
20
4400
189
177 l6l
177 178
0.46
0.87 1.05 1.06
31.5 37.6
38.7
37.9
- With 40 phr DOP -
Durometer Hardness
0
2900
293
3300
197
10
3200
260
20
2700
240
4.5 - 90 4.7 - 91 8.0 - 90
8.0 - 92
- With 60 phr DOP -
0
2400
203
5
2300
337
10
2300
283
20
2000
253
1.3 _ 76 1.3 - 79
1.7 - 79 3.9 - 83
The superiority in a typical vinyl formulation of R-G144 over Canadian chrysotile is shown in Table IV which includes data for samples prepared from Carey 7RF9 and Johns-Manvilie 7R06 asbestos.
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TABLE IV
Comparative Data with Competitive Asbestos in VYNS
(10 phr Asbestos)
None
R-G144
Carey
JM
Tens. Strength, psi Tens. Mod., psi x 10"3
Elong., %
Izod, ft-lb./in. Heat Dist. Temp., C. Color Clarity
7600
396 2 0.6
63.0 Lt. Gray
Clear
9000
531 3 0.5
69.9 Lt. Tan
Clear
7700 *470 16
0.5 64.6 Dk. Gray Opaque
7800 490
6
0.5 63.3 Dk. Gray Opaque
Formulation:
VYNS Temex 5 Advastab CH-90
rt ABC-18 Stearic acid Asbestos
100 parti 1.2 "
0.5 " 0.75 " 1.0 " 10.0 "
Union Carbide' s rigid FVC pipe compound QGPB-93H, which is based on QYTQ-7, is markedly improved in tensile strength, modulus, and Izod impact strength by the addition of R-G144. These data in Table V, do not show the increases in HDT which have been seen in other compounds and which have been reported by L. Robesonw) to be as high as 80C. with 40 per cent R-G144. In most cases the samples containing
30-k0% R-G144, were severely degraded and are not included in the tables for this
reason. Further work with QGPB-9311, including extrudability, is being done in Bound Brook.
A sample of calendered, rigid sheet based on VYNS and containing 20 phr R-G144 has been submitted to Polyplastex United. This material, known as ZCA-0511, is being evaluated as a fire-resistant structural substrate for rigid aircraft in terior parts. According to Polyplastex, this is the only material which passes a new FAA burn-through test requirement for new aircraft interior parts. R-G144 asbestos-containing compounds similar to KDA-26l8 and KDA-2034 are also reported by Polyplastex to have sufficiently low flame spread rating to be utilized in aircraft interiors. Other vinyl compounds containing R-G144 are currently under evaluation at Bound Brook and Wayne, New Jersey, and Ottawa, Illinois.
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TABLE V
QCPB-9311
r-gi44,
1
Tens., psi
Elong.,
%
Mod., psi x 10"^
Izod, ft-lb./in.
H.D.T., C.
0
8000
152
410
0.60
72.2
3
8000
139
445
0.70
71.2
5
8200
115
479
0.83
71.6
;.v6;
8 8300
7
-
0.60
71.4
10 8200 4i
490
O.85
72.4
12 8400 11
-
0.60
72.6
15 8800 5 599
0.65
70.4
20 8800 4 567
0.70
71.2
Styrene Resins
R-G144 provides a means of producing higher modulus, tougher styrene compounds. The crystal polystyrenes, SMD-3500^ are stiffened and improved in HDT, as shown in Table VI. The same magnitudes of tensile strength increase with vinyl polymers is not obtained in the polystyrenes, probably because of a lack of compatibility with the chrysotile mineral. Modification 1of the chrysotile fiber to render it less electropositive produces better reinforcement of polystyrene. For example, a 10$ increase in tensile strength can be realized by treatmenti of R-G144 with Tergitol 04, an anionic surfactant.
TABLE VI
Polystyrene, SMD-3500
R-G144 phr
Tens. Str. psi
Elong.
i
Tens; Mod. psi x 10"3
H.D.T. C.
Izod ft-lb./in.
0
5700
1.2
5
5500
1.2
10
5100
1.1
15
4400
0.8
20
4600
0.7
25
3700
0.6
*40
4400
0.5
10* 5600 1.0
452 83.4 0.39
462 84.5 0.35
483 84.9 0.38 510 86.9 0.24 535 85.4 0.27 570 88.3 0.26 720 90.7 0.32 475 84.2 0.33
*R-Gl44 treated with 5$ Tergitol 04
Styrene-acrylonitrile copolymer, RMD-4511, which is somewhat more ionic in nature than SMD-3500, has R-G144 reinforced properties which are more favorable. Typical property values are shown in Table VII. As is the case with all the styrene polymers, a brown coloration occurs which intensifies with increasing R-G144 content. The data show modulus increases, heat distortion improvement, and slight increases in tensile strength up to 10 phr asbestos. Chemical modification of the asbestos fiver can provide higher levels of reinforcement.
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TABLE VII
Styrene-Acrylonitrile, RMD-4511
R-G144 psi
Tens. Str. psi
Elong.
i
Tens. Mod. psi x 10"3
0
8800
1.9
5
8400
1.7
10
9100
1-9
15
7700
1.9
20
6700
1.8
25
6500
1.7
1*0
7600
0,9
10* 9500 1.7
507 540 611
605 667 720 1210
667
*R-G244, chemically modified asbestos
H.D.T. C.
88.8 90.5 91.6 92.8 93.6 91.3 98.0 95-3
Izod ft-lb./in.
0.28 0.37 0.30 0.40 0.32 0.32 o.4o 0.25
Attempts to reinforce ABS compounds have shown that even low levels of R-G144 cause a loss in tensile strength, elongation, and Izod, but the expected . increases in modulus and HDT. Some preliminary work has shown that chemical modi fication of R-G144 effects improvement in ABS strength and toughness such as that shown with RMD-4511.
Further work should be done to explore the possibility of devising a tougher, more heat resistant ABS material.
Polyolefins
The data shown in Tables VIII and IX show the improvements in strength, modulus, and heat resistance of polyethylene compounds containing R-G144. These property improvements are more pronounced in the high density DMD-7000, approaching the values normally associated with polypropylene. Optimum reinforcement occurs between 10 and 25 phr asbestos in both high and low density resins.
TABLE VIII
Low-Density Polyethylene, DYNH-4
R-G144, phr
0
Density, g./cc.
.9164
Tensile Strength, psi
l46o
Elongation, %
538
Tens. Modulus, psi x 10"3
18.1
Tens. Impact, ft-lb./in.3
218
Melt Index, Dg./min.
1.69
Heat Dist. Temp. C. (66 psi) 53-6
5 9465
l46o
505 24.1
ll4
1-52
51.9
10
1.009 1390 532 32.2 82 1.43
53-2
15 1.047
ll60 270
35-3 66
1.15 63.3
20 1.048
1370 58
44.3 60
.65 68.4
25 1.083
1390
53 51.1
60
.32 71.4
40 1.267
1540 8
67.9 35
.14
72.5
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TABLE IX
High-Density Polyethylene, DMD-7000
R-G144 phr Density, g./cc. Tensile Strength, psi Elongation, $ Tens. Modulus, psi x 10"^
Tens. Impact, ft-lb./in.3 Melt Index, Dg./min. Heat Dist. Temp., C.
0
9699 3200 38
177 81
4.85 49.6
.5 10 1.004 1.032
3600 3700 11 11
192 208 43 25
3.56 2.50 50.2 54.3
15 1.068
3900 10
225
35 1.78 52.6
20 I.098
3600 4
246 18
1.04
59-0
25 1.136
3600
3 257
11
52 62.5
40 1.262
3400 1
304 11
.08
65.9
In both cases, there is a drop in elongation and impact resistance.with increasing asbestos content. Melt flow decreases with increasing fibrous reinforce ment. Tests with ethylene copolymefr containing polar groups such as acrylic acid indicate that even higher levels of reinforcement are readily attainable.
The data indicate that, by proper resin selection and possibly by suitable pretreatment, the lower performance resins can be upgraded for use in areas requiring higher modulus and heat resistance. At the same time, improvements in fire resistance and dimensional stability are coincident with asbestos reinforcement, as is the case in any resin system.
wi REB:dmp
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ACKHOWLEIDGMEMTS I would like to thank Ty Hartsing and Bill Mulvaney for their helpful suggestions, and Bob Kennedy for his assistance and suggestions throughout the course of this work.
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REFERENCES
L. Steg, "Whisker and Short Fiber Reinforcement," Aeronautic and Space Engineering and Manufacturing Meeting, Los Angeles, California October 1966 (S.A.E.)
W. P. Mulvaney, "Coalinga Chrysotile Asbestos - Plasticized Vinyl Compounds," Status Report JS-206 dated May 22, 1967, Chemicals & Plastics Division
F. A. Mumpton, S. Chwastiak, and K. Park, "Properties of Union Carbide's Chrysotile Asbestos" dated May 31> 19&7, Chemicals & Plastics Division
J. F. Bliss, Epoxy Laboratory Letter, Vol. IV, Number 10 dated December 20, 1966, Plastics Division
L. Robeson, R. & D. Dept., Chemicals & Plastics Division, private communication
W. P. Mulvaney and L. Robeson, "Nylon 6 - R-GltU Asbestos Compounds, Status Report JS-210, dated June 12, 1967, Chemicals & Plastics Division
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