CA1159986A

CA1159986A - Composites of grafted olefin polymers and cellulose fibers

Info

Publication number: CA1159986A
Application number: CA000379695A
Authority: CA
Inventors: Aubert Y. Coran; Raman Patel
Original assignee: Monsanto Co
Current assignee: Monsanto Co
Priority date: 1980-06-13
Filing date: 1981-06-12
Publication date: 1984-01-03
Also published as: JPS5731567A; EP0042700B1; DE3170105D1; US4323625A; JPS649940B2; EP0042700A1

Abstract

COMPOSITES OF GRAFTED OLEFIN POLYMERS AND CELLULOSE FIBERS ABSTRACT OF THE DISCLOSURE Composites are disclosed of discontinuous cellulose fibers mixed with a methylol phenolic modified polyolefin and a bonding agent. Treated fibers are also disclosed, which are treated to reduce fiber-to-fiber interaction so as to facilitate mixing into composites.

Description

BACKGROUND OF THE INVENTION
This invention relates to composites of cellulose fibers and grafted polymers from olefins, and to cellulose fibers treated with such polymers.
It is known that the mixture of discontinuous fibers with polymeric materials can impart improved properties to the polymer;c materials, such as greater strength and stiffness. For exampjle, glass fibers incorporated into a polypropylene molding resin can produce a rigid, strong composite, su;table for a variety of appllcat;ons. The combination of discontinuous cellulosic f;bers with a variety of vulcanized elastomers is described in U. ~.
Patent 3,697,364 to Boustany and ~oran. Also, U. S.
Patent 3,943,079 to Hamed shows pretreatment of cellulosic fibers prior to incorporating them into a variety of organic polymers.

SUMMARY OF THE INVENTION
It has now been discovered that a composite formed by mixing discontinuous cellulose fibers with a grafted monoolefin polymer has particularly useful properties.
More specially, the novel composites consist essentially of from 2 to 55 weight percent of discont;nuous cellulose .

fibers, the remaining 98 to 45 we;ght percent being a matrix comprising from 2 to 99.9 parts by weight of a methylol phenolic-modified crystalline polymer from alpha olefin monomer having 2 to 4 carbon atoms, and ~t least 0.1 part by weight of a bonding agent per 100 parts matrix by weight.
It has also been found that treated fibers, compr;sing discontinuous cellulose fibers of aspect ratio greater than five, and methylol phenolic-modified crystalline polymer from alpha olefin monomer having 2-4 carbon atoms, said modified crystalline polymer be;ng present in an amount sufficient to reduce fiber-to-fiber interaction up to about 85 parts by weight per 100 parts of fibers by weight, have useful properties.
Advantageously, the fibers contained in the composites of the invention can be oriented to a greater or lesser degree, providing products having a greater strength and stiffne-s in the d;rection of orientation. Random fiber orientation, however, may be produced if isotropic compos;tes are desired, having the same degree of strength and stiffness in all directions.
The discontinuous cellulose fibers employed in the -composites and treated fibers of the invent;on inclu~e regenerated cellulose, such as rayon fibers, or any of a variety of unregenerated fibers, many of which are found in nature. Seed fibers such as cotton, woody fibers from coniferous or deciduous woods, bast fibers such as flax, and leaf or fruit fibers such as sisal or coconut can be used. Preferred are wood fibers, and espec;ally hardwood kraft, i.e., wood pulp made by the sulfite process.

li5~98~i The average aspect ratio of the cellulose fibers strongly affects the modulus obtainable in the composites of the invention. The average aspect ratio is the ratio of average length to average diameter of the fibers, and is preferably greater than five in the fibers of the invention.
More preferred fibers have average aspect ratios from 20 to 200, with average aspect ratios of from 50 to 200, or 75 to 200 being most preferred. Since some fiber breakage may result in the step of mixing the fibers into the matrix, the initial average aspect ratio can be greater than 200, but the best results are obtained with final average aspect ratios of 200 or less. Mixtures of fibers having different average aspect ratios can be usefully employed.
Hardwood fiber, because of its smaller diameter as compared with softwood fiber, is preferred, since a shorter fiber can be used within the preferred aspect ratio.
Smaller diameter fibers are more flexible, and shorter fibers are less likely to break during mixing.
The fibers can be pretreated before incorporation into the composites to reduce fiber-to-fiber interaction, and the methods of Hamed as taught in U. S. Patent 3,943,079 can be employed for this purpose. Pretreatment is effective in reducing the time and work required to incorporate the fibers into the matrix, thus reducing the amount of fiber breakage thereby. Pretreatment methods can also be used other than that in the Hamed patent, such as by slurrying the fibers in water with a polymer latex or with a particulate filler material such as carbon black, talc, or fine particle size calcium carbonate.

If it is desired to incorporate the fibers into the matrix without the use of the pretreatment steps set forth above, a portion of the modified polyolefin can be admixed in solution in a hydrocarbon solvent, which solvent is driven off in the mixer. If a matrix containing another polymer is to be employed, a polymer can be selected which is molten at the mixing temperatures employed, and which acts to coat the fibers and prevent fiber-to-fiber interaction. Addition of water to the fibers prior to mixing is helpful to plasticize and separate the fibers somewhat, to reduce the degree of fiber breakage.
The composites of the invention comprise discontinuous cellulose fibers mixed with certain modified crystalline olefin polymers. These modified polymers, which have methylol phenolic groups grafted thereto, may be prepared by the reaction of crystalline monoolefin polymer with methylol phenolic material in the presence of activator. It is believed that the activator promotes graft formation in which the methylol phenolic material is linked through a methylene bridge to the crystalline olefin polymer. The resulting modified polymer has methylol phenolic groups grafted thereto. Some of the methylol phenolic groups may be pendant to the olefin polymer chain, being attached by a single link, while other methylol phenolic groups may form links between two olefin polymer molecules.
Preparation of the modified crystalline alpha-olefin polymers of the invention is described in our co-pending Canadian Patent Application S.N.367,843, filed January 2, 1981.

il59~

_5_ Suitable olefin polymers for modification compr;se crystall;ne homopolymers or copolymers of Cz-C4 alpha monoolefins (alkenes). An important subgroup of satis-factory olefin polymers comprises crystalline, high molecular weight sol;d products from the polymer;zat;on of one or more monoolef;ns by e;ther h;gh pressure or low pressure processes. Examples of such polymers are the ;sotact;c or synd;otact;c monoolef;n polymers, representa-t;ve members of wh;ch are commerc;ally ava;lable. Examples of sat;sfactory olef;n monomers are ethylene, propylene7 l-butene, 2-methyl-1-propene, and mixtures thereof.
Commerc;ally ava;lable thermoplast;c crystall;ne polyolef;n res;ns and preferably polyethylene, polybutene-l, and polypropylene, or m;xtures thereof, may be advantageously used ;n the pract;ce of the ;nvention, w;th polypropylene being preferred. Also suitable for the practice of this ;nvent;on are copolymers of two or more olef;ns, such as copolymers of ethylene and propylene, which copolymers are preferred.
Methylol phenolic materials which will form grafts with olefin polymers may be used in the practice of the invention. A suitable methylol phenolic material may be prepared by condensation of an unsubstituted phenol,~
Cl-Clo alkyl-p-substituted phenol or halogen substituted phenol with an aldehyde, preferably formaldehyde, in an alkal;ne medium, or by condensation of phenol dialcohols.
Methylol phenolic material includes polymeric phenols containing up to 10 benzene rings, but preferred mater;als contain no more than three benzene rings. Especially preferred are methylol phenolic materials derived from dimethylol phenol subst;tuted with Cs-Clo alkyl groups, preferably tertiary alkyl groups, ;n the para position.

ii599~16 Examples of satisfactory dimethylol phenolic materials are described in U.S. Patent Nos. 2,972,600; 3,093,613;
3,2~7,440; 3,709,840; and 3,211,804, Column 5, lines 3-67.
Halogenated (for example, brominated) methylol phenolic materials are also suitable. These halogenated materials, at elevated temperatures in the presence of metal oxide such as zinc oxide, can form Lewis acid activators in situ.
Suitable methylol phenolic materials are commercially available.
Generally, any activator which promotes the graft formation between olefin polymer and methylol phenolic material is suitable for the practice of the invention.
Preferred activators are Lewis acids, which include the acid-acting metal halides such as boron trifloride, stannous chloride, zinc chloride, titanium tri- or tetra-chloride, aluminum chloride, ferric chloride, ferric bromide, zinc bromide, aluminum bromide, or complexes thereof.
In useful composites of the invention, cellulose fibers are incorporated into a matrix containing phenolic modified crystalline olefin polymer which is modified by the action of as little as 0.01 weight percent of methylol phenolic material. Preferred modified polymers of the invention contain between 0.1 and 20 weight percent of methylol phenolic material.
The composites of the invention also contain a bonding agent, present in an amount of at least 0.1 part by weight per 100 parts by weight of the total matrix.
Preferably, the composition will contain from about 0.5 to about 10 parts by weight of the bonding agent, per 100 parts of matrix, although lesser amounts, down to 0.1 part by weight per 100 parts by weight of matrix can be ii~9~86 43-51-lOSlA

effective, depending on the nature of the bonding agent and the ratio of amounts of f;bers and matr;x. More than 10 parts by weight of bonding agent per 100 parts of the matrix is usually not needed, althouch excess amounts can be employed if desired~
The bonding agents which are effective in the compo-sites of the invention include, broadly, those agents wh;ch have been found to be effective in enhancing adhesion with cellulosic materials, for example, isocyanate-containing bonding agents. These agents include diiso-cyanates, such as methylene-bis-phenylisocyanate, polyiso-cyanates, such as tri(isocyanophenyl)methane, and polymeric polyisocyanates, such as polymethylene polyphenylisocyanate (PAPI). Blocked isocyanate compounds are also useful, wherein the reactive isocyanate group is protected by a blocking substituent which in turn is subsequently removed to allow the isocyanate group to react with the cellulosic fibers and form a bond with the matr;x material.
Phenol-aldehyde resins are also effective bonding agents in the compos;tes of the ;nvent;on. Among these materials are phenol-formaldehyde resins and resorcinol-formaldehyde res;ns. Resol res;ns, condensed from a phenol and an aldehyde under alkal;ne cond;t;ons, art particularly effective.
Amino-phenol res;ns are also useful as bonding agents, and include, for example, melamine-formaldehyde resins.

li59986 43-51-105lA
_~_ Other known textile-to-rubber bonding systems can be included ;n the matr;x as well. For example, a resorcinol resin can be incorporated in the matrix, together w;th a methylene donor. Another system, descr;bed by Mor;ta U. S. Patent 3,644,268, uses an alkylene-resorc;nol polymer together w;th hexamethylene tetram;ne as a methylene donor.
Generally, when ;socyanate bond;ng systems are used, an amount of from 0.1 to 2.5 parts by we;ght ;n 100 parts by weight of the matrix is sufficient to opt;m;ze adhes;on of the fiber to the matr;x. When phenol-aldehyde or amine phenol resins are employed, a greater amount of bond;ng agent is normally used, such as from about 3 to about 10 parts by weight, based on 100 parts by weight of the matrix.
In addit;on to the modif;ed crystall;ne poly~alPha olefin) polymers and the bonding agents descr;bed above, the matrix can conta;n other materials such as other polymers, f;llers, re;nforc;ng p;gments and plast;c;zers.
Among the other polymers wh;ch can be included in the matrix are unmodif;ed poly(alpha-olef;ns), such as polyethylene, polypropylene, polybuty~ene, and copol3~mers such as ethylene propylene copolymers. These poly(a~pha-olefins) can be amorphous as well as crystall;ne.
Hydrocarbon rubbers can also be present, such as natural rubber, styrene-butad;ene copolymer rubber, polychloro-prene, polybutadiene, butadiene-acrylonitrile rubber, synthetic polyisoprene, butyl ru~ber and EPDM rubber. The hydrocarbon rubbers can optionally be vulcanized, either partially or completely. Of particular interest is inclusion of f;ne part;cle s;ze (less than 5û m;crometers average) cured EPDM rubber. These other polymers can be 11~9~8~i ~3-51-lOSlA
_9_ present in the matrix ;n amounts of from 1 to ~5 parts by we;ght, ;n the case of crystall;ne polyolef;ns, and ;n amounts of from 1 to 60 parts by weight in the case of hydrocarbon rubbers, in each case per 100 parts by weight of the matr;x. Mixtures of two or more of these polymers can be used; among them are polyolef;n EPDM rubber blends as shown in U.S. Patent 4,130,535.
Fillers which can be included in the matrix composi-tion include the f;llers ord;nar;ly used ;n rubber and plastic formulations, such as calcium carbonate, talc, clay, feldspar and the like. Reinforcing pigments, such as carbon black and sil;ca, can also be employed. The use of f;llers or reinforcing pigments, and the amounts used will be dictated by product performance and cost requ;rements.
Plast;cizers can be included in the matrix composi-tion if the matrix composition comprises a rubbery polymer, provided that they are compatible w;th the part;cular rubbery polymer used. Plast;cizers can be dioctylphthalate, mineral oils, rubber processing oils or fact;ces. Again, the amounts of plasticizers and their types w;ll depend on the desired propert;es of the fin;shed composite.
Preferred composites of the invention are free ~f acidic mater;als capable of promoting the hydrolysis of cellulose, or, in the alternative, contain materials which neutralize acids. Composites which are subjected to elevated temperatures, either in service or in the processing steps of manufacture, are susceptible to the d2generating effects of hydrolysis of the cellulose fibers. Thus, in the case of those composites which must withstand heat, it is preferred that they either contain i`l~9986 no acid;c mater;als, or that they conta;n ac;d acceptors.
Ac;d;c materials wh;ch could accelerate hydrolysis of cellulose ;nclude inorganic or organic acids, acid salts, and materials which form acids on heat;ng or ag;ng of the compos;tes. Alternat;vely, ac;d-accept;ng mater;als can be ;ncorporated ;n the matrix. Examples of such materials are calc;um ox;de, calc;um carbona~e and magnes;um ox;de.
Normally, the amount of ac;d-acceptor used w;ll be at least suff;c;ent to neutralize the Lew;s acid act;vator, although greater amounts can be employed for safety.
The treated f;bers of the ;nvent;on are des;gned to be used in preparing composites of fiber and polymer, e;ther the compos;tes of the instant invention or composites which are outside the scope of th;s invention. By virtue of their pretreatment, the incorporation of these fibers ;nto rubber or plast;c polymers ;s fac;l;tated, and the propert;es of the compos;tes ;nto wh;ch they are ;ncorpor-ated are ;mproved and enhanced.
As broadly stated above, the treated f;bers of the invent;on are cellulose f;bers with a coating compris;ng a modified crystalline polymer disclosed above. The amount of the coat;ng wh;ch ;s present ;n the treated f;bers is no more than 85, preferably no more than 50 parts by we;ght of coat;ng per lO0 parts of cellulose f;bers.
The m;nimum amount of coating present ;s the least amount wh;ch will reduce f;ber-to-f;ber ;nteract;on, and w;ll vary accord;ng to the selection of fiber and coating.
Normally, at least five parts by we;ght of coat;ng are needed, and preferably, from lO to 30 parts are used, per lO0 parts of fibers by we;ght.

11~9~86 The cellulose fibers have an average aspect rat;o of at least five, and preferably from 20 to 200. When the fibers are used in a relatively soft matrix material, the average aspect ratio is preferably from 50 to 200, more preferably from 75 to 200. As with the composites described above, the fibers are preferably unregenerated cellulose, more prefera~ly wood puTp, and most preferably hardwood pulp. The contained polymer ;s preferably modified crystalline polypropylene, and the polymer is preferably free of acidic materials capable of promoting the hydrolysis of cellulose.
The composites or treated fibers may be prepared by mix;ng, preferably above the melting point or softening point of the polymers, by using convent;onal masticating equ;pment, for example, rubber m;lls, Brabender Mixers, Banbury M;xers, or twin screw continuous mixer extruders.
Mixing t;mes necessary to obtain a hQmogeneous m;xture are satisfactory.
The composites of the invention are useful for making a var;ety of molded, extruded, or calendered articles~
They are particularly useful in making articles by extrusion, ;nject;on mold;ng-, and transfer molding techni-ques. The properties of the composites depend upon t~he compos;t;on of the matrix and the relative proportions of f;bers and matrix, w;th a wide range of properties available simply by vary;ng the proport;ons of the fiber and matrix.
The stress-stra;n propert;es of the composites are determ;ned ;n accordance with ASTM test procedures. Tests are carried out using a M;crodumbbell tens;le test spec;men (ASTM D1708-66) having a test length of 0.876 inches (2.23 ~1~9~86 43-Sl-1051A

cm). An Instron tens;le tester was used to pull the specimens apart during the test for tensile strength and ultimate elongation. The tester is designed to measure changes in jaw separat;on in inches. Though the ;nit;al jaw separation was adjusted to the ASTM procedure, to 0.90 inches (2.29 cm.) and the specimen length and jaw separation are not 1~00 inches (2.54 cm.), the elongation at break was read as the jaw separation increase in inches. The percent ultimate elongat;on or elongation at break was calculated by mult;plying the change in jaw separation required to break the specimen (measured in ;nches) by 100. It ;s true that the original unstrained sample length was 0.876 inches (not 1.00 inches) and one might expect that the change (in inches) in jaw separation should be divided by 0.876 inches as well as being multi-lS plied by 100. However, it is also true that some flow ofthe specimen occurs in the jaws, which flow, in effect, somewhat increases the initial or unstrained length. Since the effect;ve length change due to flow of the spec;men ;n the jaws is difficult to measure in each case, and since the effect of this is ;n the opposite direction of not d;v;ding by 0.876, it was found expedient to estimate the percent ultimate elongation or elongation at break, ~erely by multiplying the jaw separation to break (measured in ;nches) by 100. The actual value may deviate from th;s somewhat, however, the method presented herewith ;s incorporated into the definition for percent elongat;on used here;n. Test specimens are pulled at 2.5 cm. per minute.

il5998~ 43-51-1051A

As ment;oned prev;ously, the fibers can be present in the composites of the invent;on in an unoriented, or random fashion. Alternatively, the fibers can be oriented, to a greater or lesser degree, so that their axes are predominantly in a part;cular d;rect;on. In general, pass;ng a fluid mixture of fibers and matrix through a constricted flow zone will cause some degree of orienta-tion of the f;bers ;n the d;rect;on of flow. For example, extrus;on or passage of molten material through the nip of a rubber mill will tend to turn at least some of the fibers into the direction of flow. Repeated passages of molten composit;on through a m;ll can result in a rather high percentage of the fibers oriented in the direction of flow. Other types of orientation can result from extrusion of the composites of the invention, as shown in U. S. Patent 4,056,591, wherein a predominantly circum-ferential orientat;on of d;scontinuous fibers can be achieved in an extruded hose by use of special die configurations. Similarly, U. S. Patent 4,057,610 shows the product;on of extruded hose ;n wh;ch the fibers are radially oriented in the matrix.
By orienting the fibers in objects formed from the composites of the invention, an;sotropic properties ~an be achieved in the objects, whereby the strength and st;ffness in the direction of predominant orientation is enhanced. For example, ;n pipe or hose conta;n;ng f;bers hav;ng a predom;nantly circumferential orientation, the burst strength is considerably greater than if the fibers were otherw;se or;ented.

~5998~ 43-51-105lA

DESCRIPTION OF THE PREFERRED EMBODIMENTS
The mod;f;ed crystall;ne polyolefins of the ;nvention are prepared by mast;cat;ng the components ;n a Brabender m;xer at the o;l bath or stock temperatures and m;x;ng speeds ;nd;cated below. A11 parts are by we;ght, and the total charge ;s generally adjusted to about 55 to 65 ml.
EXAMPLE I
To prepare crystall;ne polypropylene hav;ng methylol phenol;c groups grafted thereto, 100 parts of polypropylene ~Profax~ 6723, sold by Hercu7es, Inc.) are charged to the m;xer and masticated at 80 rpm with an oil bath tempera-ture of about 180C. After the polypropylene is molten,

2 parts of dimethylol-p-octylphenol (sold by Schenectady Chemicals, Inc., under the designat;on SP-1045) are added and mixing ;s cont;nued for 2 minutes. Act;vator, 0.4 parts of stannous chloride d;hydrate, is then added and mixed for 3 more minutes. Lastly, 0.07 parts of magnesium ox;de ;s added ~to neutral;ze any free ac;d) and the batch is mixed for one additional m;nute. Dur;ng the mixing, the stock temperature reaches 185 to 190C. The mass ;s then removed.
EXAMPLE II
To prepare crystalline polyethylene hav;ng methylol phenolic groups grafted thereto, 100 parts of high dens;ty polyethylene (Marlex~ EHM 6006, sold by Ph;ll;ps Chem;cal Co.) are charged to the mixer and masticated at 80 rpm at about 185-190C. Four parts of dimethylol-p-octylphenol are added and m;x;ng ;s cont;nued for one m;nute.
Activator, 0.8 parts of SnC12.2H20, ;s then added and ~;99~fi mixed for 3 additional minutes. Magnesium oxide, 0.32 parts, is added and mixed for one minute. The product is then removed.
In a subsequent mix;ng operation, the modified crystalline polyolefins produced as described above are mixed with varying amounts of cellulose fibers to produce composites in which the fibers are oriented, and by subsequent molding operations, useful objects are produced.
EXAMPLE III
It ;s somet;mes desirable to comb;ne the steps of modifying the crystalline polyolefins and incorporating the fibers into a single mixing operation. To illustrate this technique, fibers were mixed with crystall;ne polypropylene (Profax 6723), both modified and unmod;fied.
To evaluate the contr;bution of a bonding agent, a small amount of polymethylene polyphenyl isocyanate (PAPI) was also used in both the mod;f;ed and unmod;f;ed samples.
Forty-e;ght grams of Profax 6723 were charged to the Brabender mixer with the oil bath temperature at 180C, and mixed at 80 rpm until the polypropylene melted.
Twelve grams of dry Pinnacle~ hardwood pulp ~sold by Westvaco Corp., and contain;ng added water) were the~ added and mixed for eight minutes until dispersed. During this time, small amounts of water were added to aid dispersion.
After the last water evaporated, the temperature of the batch reached about 190C. The mixture was removed, passed repeatedly in the molten state, through a roll mill to orient the fibers, and compression molded ~with minimum flow) at 210C. The molding was then removed and cooled prior to testing, and identified as sample A. Another m;xture was produced in the same manner, except that 1.44 ii~998~;

grams of PAPI were added after the polypropylene and fibers had mixed for six minutes, and the co~bination was mixed for two additonal minutes, then removed, milled, molded and cooled as before, and identified as sample B.
F;nally, a th;rd sample was prepared by m;x;ng 48 grams of molten polypropylene with 0.96 gram of SP-1056 (d;methylol-p-octylphenol, brom;nated 2-lOX, Schenectady Chem;cals, Inc.) for two minutes, adding 0.25 gram ~;nc ox;de and m;xing one minute, then adding the wood pulp and mixing as above, five minutes~ then adding 1.44 grams PAPI and mixing for two m;nutes, and add;ng 0.25 gram MgO
and mixing for two minutes more. The third sample was remove-d, milled, molded and cooled, and identified as sample C. In all three samples, the polymer-f;ber rat;o was 80 parts polymer to ZO parts fiber, by weight.
Physical propert;es (in the predominant fiber d;rection) were run on the three samples, w;th the results shown in Table I, follow;ng.

TABLE I
Properties A B C
Ultimate Tensile Strength, MPa 28.0 24.7 3~.9 Modulus, MPa 854 799 972 Ultimate Elongation, X 17 19 17 li~i9986 43-51-lOSlA

The results shown in Table I indicate that the use of the modified crystalline polypropylene ~sample C) gave a 35% improvement in ultimate tensile strength and a 14%
improvement in modulus as compared with the control (sample A). The PAPI bonding agent by itself did not appear to produce any improvement at all, sample B giving poorer results than the control.
EXAMPLE IV
A fiber masterbatch was prepared by charging 1106 grams of Pinnacle pulp (containing ambient moisture;
lQ40 grams dry pulp) and 260 grams of A-FAX~ 900D amorphous polypropylene ~sold by Hercules, Inc.) into a Banbury mixer. The mixture was masticated 12 minutes at low speed with cooling water on to control the temperature below 120C. The batch was then discharged and cooled for later use. This masterbatch had a polymer-to-fiber ratio of 20 polymer/80 fiber, by weight.
Composites of fibers and matrix were then prepared using the masterbatch described above for the fiber source. Molten polypropylene ~Profax 6723) was mixed in the Brabender mixer with varying levels of SP-1056 for one minute. Then zinc oxide was added, followed by two minutes of mixing. The fiber masterbatch was then charged, and dispersed with 2-3 minutes of mixing. The PAPI and MgO were charged at one minute intervals, and the composite was finally mixed for two minutes before discharge and cooling. The Brabender oil bath was main-tained at 180C and the m1xer speed was 80 rpm throughout.

~5g986 43-51-105lA

Levels of SP-1056, zinc oxide, MgO and PAPI were varied as shown in Table II, following, with all amounts in grams. Test results are shown for the samples after extrusion to orient the fibers.
The matrix-to-fiber ratio range for all samples was calculated to be from 70 matr;x/30 f;ber to 71.5 matr;x/
28.5 f;ber by weight.
The test results as shown ;n Table II ;ndicate that improved phys;cal propert;es result as the level of SP-1056 ;s ;ncreased, up to about 0.15 or 0.30 grams, and that h;gher levels of the mod;fying material do not appear to give further ;mprovement. Sample 7 shows that when the bonding agent is omitted, much poorer physical propert;es result. In Table II, the parts by weight are expressed as grams per Brabender m;xer batch.

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~159986 43-51-1051A

EXAMPLE V
Two fiber masterbatches were prepared as follows: -a modified crystalline polypropylene sample was first prepared by charging 100 grams of Profax 6723 and 1.5 grams of SP-1056 to the Brabender m;xer, with o;l bath temperature at 180C and rotor speed at 80 rpm. When the batch temperature reached 190C, 1.5 gra~s of ~;nc oxide were added and mixing was continued for three more m;nutes.
By using the modified crystalline polypropylene prepared above, a fiber masterbatch was made by charging 10 grams of the modified crystalline polypropylene to the Brabender m;xer, then adding 40 grams (dry) of wood pulp dampened with water and ten grams of xylene. Mix;ng proceeded until the sample reached 145C, when ten more grams of xylene and an equal amount of water were added.
The m;xture was again masticated until its temperature reached 145C, when 10 more grams of xylene were added, and m;x;ng continued unt;l the temperature reached 180C, w;th rotor speeds varying from 50 to 80 rpm. After dispersing the fibers, the fiber concent-rate was removed.
Twenty-five grams of the fiber concentrate was melt ~ixed with 40 grams of the modified polypropylene, then 0.8 gram of PAPI was added, and mixing continued for 1-2 minutes. Magnes;um oxide was charged (0.2 gram) and mixed ;n for one more minute. A sheet was formed and oriented on the mill using a 70 mil (1.8 mm) nip. Sheets were molded in a press at 210C and cooled under pressure.

~,iS99~6 A control sample was prepared from a sample of unmodified crystalline polypropylene (in both the concen-trate and the composition) and cellulose fibers in the same manner, except that the SP-1056, zinc ox;de, PAPI
and magnesium oxide were omitted. In both instances, the concentrate or masterbatch had a polymer/fiber ratio of 20/80 and the final mixture had a matr;x/fiber ratio of about 70/30.
Physical tests of the two samples showed that the mod;fied crystall;ne polypropylene gave a compos;te hav;ng an ult;mate tens;le strength of 63.5 MPa compared w;th the control at 36~1 MPa, a modulus of 2325 MPa compared with the control at 1598 MPa, and an ultimate elongation of 7% compared with 8% for the control.
Although the invention has been illustrated by typ;cal examples, it is not limited thereto. Changes and modifi-cations of the examples of the invention here;n chosen for purposes of disclosure can be made which do not constitute departures from the spirit and scope of the invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A composite consisting essentially of from 2 to 55 weight percent of discontinuous cellulose fibers, the remaining from 98 to 45 weight percent being a matrix comprising from 2 to 99.9 parts by weight of a methylol phenolic modified crystalline polymer from alpha olefin monomer having 2 to 4 carbon atoms, and at least 0.1 part by weight of a bonding agent per 100 parts of matrix by weight.

2. The composite of Claim 1, wherein the methylol phenolic modified polymer is a modified crystalline polymer of propylene.

3. The composite of Claim 1, wherein the polymer is a modified crystalline copolymer from ethylene and propylene.

4. The composite of Claim 1, wherein the methylol phenolic modified polymer is the product of the reaction of 100 parts by weight of crystalline polymer from propy-lene with about 0.1 to 20 parts by weight of a methylol-phenolic material.

5. The composite of Claim 4, wherein the matrix comprises from 0.5 to 10 parts by weight of bonding agent.

6. The composite of Claim 1, which is free of acidic materials capable of promoting the hydrolysis of cellulose.

7. The composite of Claim 1, wherein the matrix contains acid-accepting materials.

8. The composite of Claim 1, wherein the fibers have an average aspect ratio of at least five.

9. The composite of Claim 2, wherein the fibers have an average aspect ratio of from 20 to 200.

10. The composite of Claim 9, wherein the fibers are unregenerated cellulose.

11. The composite of Claim 10, wherein the fibers are wood pulp.

12. The composite of Claim 11, wherein the fibers are hardwood pulp.

13. The composite of Claim 1, wherein the fibers are pretreated to reduce fiber-to-fiber interaction.

14. The composite of Claim 2, wherein the bonding agent is selected from the group consisting of diisocyan-ates, polyisocyanates, polymeric polyisocyanates, blocked isocyanates, phenol-aldehyde resins and amino-aldehyde resins.

15. The composite of Claim 10, wherein the bonding agent is selected from the group consisting of phenol-aldehyde resins, amino-aldehyde resins, diisocyanates, polyisocyanates, polymeric polyisocyanates and blocked isocyanates, wherein the average fiber aspect ratio is from 50 to 200.

16. The composite of Claim 1, wherein the matrix comprises from 2 to 95 parts by weight of unmodified poly(alpha olefin).

17. The composite of Claim 15, wherein the matrix comprises from 1 to 75 parts by weight of fully cured particulate EPDM rubber.

18. The composite of Claim 17, wherein the matrix contains fillers and extender oils, and the average fiber aspect ratio is from 75 to 200.

19. Treated fibers comprising discontinuous cellulose fibers of aspect ratio greater than five and methylol-phenolic modified crystalline polymer from alpha olefin monomer having 2 to 4 carbon atoms, said modified crystalline polymer being present in an amount sufficient to reduce fiber-to-fiber affinity up to about 85 parts by weight per 100 parts of fibers by weight.

20. Treated fibers of Claim 19, wherein the fibers have an average aspect ratio of at least five.

21. Treated fibers of Claim 19, wherein the fibers have an average aspect ratio of from 20 to 200.

22. Treated fibers of Claim 19, wherein the fibers are unregenerated cellulose.

23. Treated fibers of Claim 19, wherein the fibers are wood pulp.

24. Treated fibers of Claim 19, wherein the fibers are hardwood pulp.

25. Treated fibers of Claim 19, wherein the crystalline polymer comprises modified crystalline poly-propylene.

26. Treated fibers of Claim 19, which is free of acidic materials capable of promoting the hydrolysis of cellulose.