GB2505438A

GB2505438A - Pre-treated cellulosic material admixed with polymer

Info

Publication number: GB2505438A
Application number: GB1215381.3A
Authority: GB
Inventors: Peter Hammond
Original assignee: CCM Research Ltd
Current assignee: CCM Research Ltd
Priority date: 2012-08-29
Filing date: 2012-08-29
Publication date: 2014-03-05
Anticipated expiration: 2032-08-29
Also published as: GB201215381D0; GB2505438B

Abstract

A method of preparing a polymeric composition comprising admixing pre-treated cellulosic material, such as wood fibres, and a polymer component, such as polyethylene or polypropylene. The cellulosic material is pre-treated with [a] an amino compound, such as ammonia or an amine, such as 2-amino-2-methyl-propanol (AMP); [b] a source of metal ions, such as sodium hydroxide, and [c] carbon dioxide or a mixture thereof, such as carbon dioxide or carbon dioxide with sulphur dioxide and then fed into an extruder with polymer pellets.

Description

Improved Materials The present invention relates to materials having improved and useful properties and to methods relating to the manufacture of said materials. In particular the present invention relates to a method of improving polymeric materials.

Polymeric materials are used for a wide variety of applications and are used in very large quantities. Some of these materials are recyclable but others are not, and in any case recycling can be expensive and uses energy. Plastics materials are used for packaging and huge quantities are thrown away. It would be useful to be able to reduce the consumption of plastic materials and improve the environmental profile of these materials.

It is known to incorporate other materials into plastic for a number of reasons. In some cases this may be to change the properties of the material, for example to provide improved mechanical strength. In some cases a natural material may be used to replace some of the plastic in order to improve the environmental profile.

Synthetic materials for example glass fibres or carbon fibres are often included in a plastics material to improve its strength and provide reinforcing properties. However, when untreated wood fibres, for example, are included in a plastic material, the strength is not usually improved to such an extent.

There is an increasingly urgent need to reduce emissions of carbon dioxide into the atmosphere. Materials which include carbon dioxide removed from the atmosphere have environmental benefits and are desirable. The present invention may provide a method by which carbon dioxide can be incorporated into a useful product.

According to a first aspect of the present invention there is provided a method of preparing a polymeric composition, the method comprising the steps of: (a) contacting a cellulosic material with a composition comprising an amino compound; (b) contacting the cellulosic material with a composition comprising a source of metal ions; (c) contacting the cellulosic material with a composition comprising carbon dioxide or a mixture thereof; and (d) admixing the cellulosic material with a polymer component.

The present invention provides a polymeric material in which fibres of cellulosic material are dispersed. By this we mean that the fibres are spread at least to some extent throughout the material. That is, in preferred embodiments the fibres are not "clumped" together in one region of the polymeric material. The fibres may be dispersed throughout the material in a regular array or in an irregular fashion. Preferably the fibres are randomly dispersed throughout the material, with a substantially even distribution.

The method of the present invention involves the treatment of a cellulosic material.

The cellulosic material may be a natural material or it may be a synthetic material, or it may be a semi-synthetic material, for example a natural material processed into a different form.

Suitable materials include a natural cellulosic material or a semi-synthetic, processed, cellulosic material, for example, rayon or lyocell. The cellulosic material may comprise natural fibres and/or synthetic fibres and/or semi-synthetic fibres, for example regenerated cellulose products. Preferably the material comprises natural fibres.

The use of natural fibres may help improve the environmental profile of the polymeric material prepared by the method of the present invention.

Preferably the cellulosic material of the present invention is derived from plant fibres, for example vegetable fibres, or wood fibres.

Suitable natural fibres for use in the method of the present invention include cotton, hemp, flax, silk, jute, kenaf, ramie, sisal, kapok, agave, rattan, soy bean, vine, banana, coir, stalk fibres, The cellulosic material is preferably in the form of small strands or fibres, or in powdered or particulate form. The size and shape of the particles or strands of cellulosic material will depend on the source from which it is derived. For example the cellulosic material may comprise fines from the processing of wood fibres.

In another embodiment the cellulosic material may be derived from the waste products of bioethanol production.

Suitably the cellulosic material is provided in the form of strands or particles having an average size of less than 5 cm, for example less than 3 cm or less than 1 cm. In some emboiments the cellulosic material is provided in the form of strands or particles having an average size of less than 5 mm, preferably less than 1 mm. A typical size of less than 5 mm, preferably less than 1mm. A typical size may be from Ito 100 pm, preferably from 5 to 50 pm, preferably from 10 to 20 pm.

The size of the strands or particles of cellulosic material may be selected to suit the intended final application of the polymeric material.

Step (a) comprises contacting the cellulosic material with a composition comprising an amino compound. The amino compound may be any compound containing an amino or substituted amino moiety for example ammonia, an aliphatic or aromatic amine, an amide or urea.

Preferably the amino compound is selected from ammonia or an amine. Any suitable amine may be used including aromatic and aliphatic amines. Preferred amines are aliphatic amines for example alkyl amines, alkenyl amines or alkynyl amines. Such amines may be substituted or unsubstituted. Suitable substituted amines include amino acids and alcohol amines (alkanolamines), for example of formula R1R2R3N where R1 is a group of formula HO-X-where X represents a 01-4 alkylene group, preferably an ethylene group, R2 represents a hydrogen atom or a group of formula HO-X-, and R3 represents a hydrogen atom or a group of formula HO-X-(the groups X being the same or different). Monoalkanolamines and dialkanlamines are preferred, especially ethanolamine (diethanolamine and/or monoethanolomine).

Especially preferred amines for use herein are alkyl amines, most preferably unsubstituted alkyl amines and alkanolamines.

The amino compound may be ammonia, a primary amine, a secondary amine or a tertiary amine. Preferred amines for use in step (a) of the present invention are primary amines, secondary amines, or mixtures thereof, including alkanolamines. Especially preferred amines for use herein are primary or secondary alkyl amines, especially alkyl amines having up to 12 carbon atoms, preferably up to 10 carbon atoms, suitably up to S carbon atoms, more preferably up to 6 carbon atoms, for example up to 4 carbon atoms. Preferred amines for use herein are methylamine, dimethylanine, ethylamine, diethylamine, propylamine, dipropylamine, butylamine, dibutylamine, 2-amino-2-methyl-propanol, and mixtures and isomers thereof. In an especially preferred embodiment step (a) comprises contacting the surface of the material with a composition comprising ethylamine, diethylamine or a mixture thereof. In another preferred embodiment step (a) comprises contacting the surface of the material with a composition comprising 2-amino-2-methyl-propanol.

The composition used in step (a) of the method of the present invention may comprise neat concentrated amino compound in gaseous or liquid form or it may comprise one or more further components including, for example, a diluent or carrier. Preferably the composition used in step (a) is a liquid composition. This may be applied by any suitable technique such as will be well known to the person skilled in the art. For example it may be applied by spraying, padding or, immersion. Suitably a solution of amine in a solvent may be applied to the material and then the material dried to effect evaporation of excess solvent and/or amine.

Suitable solvents include water, organic solvents and mixtures thereof. In some embodiments the composition used in step (a) comprises an amino compound provided as a vapour.

Suitably in such embodiments the material is placed in a sealed vessel and the amino compound vapour is then passed through the vessel.

In preferred embodiments step (a) comprises contacting the cellulosic material with a composition comprising at least 10 wt% amino compound, preferably at least 20 wt% amino compound, suitably at least 40 wt%, at least 60 wt% or at least 70 wt%. Suitably step (a) comprises applying a composition comprising up to 100 wt% amino compound, for example up to 95 wt% or at least 90 wt%.

In preferred embodiments step (a) comprises contacting the cellulosic material with a composition comprising from 10 to 40 wt% amino compound.

Preferably the composition containing an amino compound contains at least 5 wt% water, preferably at least 10 wt% water, for example about 20 wt% water. In some embodiments the composition may comprise up to 50 wt% water.

Some preferred compositions for use in step (a) consist essentially of water and the amino compound. The amino compound is preferably in an amount as defined above and the water is the balance of the composition.

The skilled person will however appreciate that commercially available amines often contain mixtures and/or impurities.

In some preferred embodiments the composition comprises the amino compound as a neat liquid.

However, the presence of water in the composition containing the amino compound is believed to be beneficial and is preferred.

Step (a) may be carried out at any suitable temperature and pressure. Suitable temperatures include from 0 to 80°C, for example from 5 to 60°C, suitably from 10 to 40°C, for example from to 35°C. Suitably in step (a) the material is contacted with a composition comprising an amino compound at room temperature. Step (a) may be carried out under high pressure.

However in preferred embodiments step (a) involves contacting the material with an amino compound under standard atmospheric pressure.

Preferably the contact time of the cellulosic material with the composition comprising the amino compound is from 0.1 to 500 minutes, preferably from 1 to 200 minutes, for example from 2 to minutes, suitably from 5 to 60 minutespreferably from 10 to 40 minutes.

Suitably in step (a) of the method of the present invention an interaction occurs between the surface of the cellulosic material and the amino compound. Any type of interaction may occur and depends on the particular amino compound. The surface of the material and the amino compound are believed to interact in a way which (though not at present fully understood) appears to promote the take-up of carbon dioxide in step (c).

Without being bound by theory, it is believed that hydrogen bonding occurs between the amino functionality and the surface of the cellulosic material.

The uptake of the amino compound by the cellulosic material is suitably at least 5% omf, preferably at least 10% omf, more preferably at least 15% omf, for example at least 20 % omf The uptake of the amino compound on the cellulosic material may be up to 100% omf, preferably up to 80% omf, more preferably up to 70% omf, for example up to 60% omf.

By % omf (% on mass of fibre) we mean to refer to the mass of amino compound as a percentage of the mass of the fibres treated.

Step (b) of the method of the first aspect of the present involves contacting the cellulosic material with a source of metal ions.

Suitable metal ions include any monovalent, divalent and trivalent ions, especially those having low toxicity.

Preferred metal ions include alkali metal ions and alkaline earth metal ions. Especially preferred are alkali metal ions. Most preferred are sodium ions.

The metal ions are preferably provided in aqueous solution. They may be provided in the form of a salt.

Preferably the source of metal ions is an alkali metal hydroxide solution. Most preferably it is a solution of sodium hydroxide.

Suitably in step (b) the cellulosic material is contacted with a composition comprising at least 5 wt% of an alkali metal hydroxide, preferably atleast 10 wt%, more preferably at least 15 wt%, for example at least 20 wt% or at least 25 Wt%.

Suitably in step (b) the cellulosic material is contacted with a composition comprising up to 60 wt% of an alkali metal hydroxide, preferably up to 50 wt%, more preferably up to 40 wt%, for example up to 35 wt%.

Step (b) may be carried out before step (a), after step (a), or at the same time as step (b).

In some embodiments steps (a) and (b) are carried out simultaneously. Step (a) may therefore comprise contacting the cellulosic material with a composition comprising an amino compound and a source of metal ions. Such a composition may be prepared by admixing an aqueous composition comprising 10 to 50 wt%, preferably 20 to 40 wt% of an alkali metal hydroxide with a composition comprising 50 to 10 wt%, preferably 70 to 90 wt% of an amino compound.

In such embodiments the cellulosic fibres may optionally be contacted with a further source of metal ions in a subsequent step.

Preferably step (b) is carried out after step (a).

Preferably step (b) is carried out at a temperature of from from 0 to 100°C, suitably from 0 to 80°C, for example from 10 to 50°C. Suitably step (b) is carried out at ambient pressure.

Preferably in step (b) the cellulosic material is contacted with a composition comprising a source of metal ions for a period of between 0.1 and 500 minutes, preferably between 1 and minutes, more preferably between 2 and 100 minutes, suitably between 5 and 60 minutes,for example between 10 and 40 minutes.

The uptake of metal ions in step (b) is preferably at least 1% omf, preferably at least 5% omf, suitably at least 10% omf.

The uptake of metal ions on the cellulosic fibre may be up to 100% omf, suitably up to 75% omf, for example up to 50% omf or up to 30% omf Step (c) of the method of the present invention involves contacting the cellulosic material with a composition comprising carbon dioxide, sulfur dioxide or a mixture thereof Steps (c) of the present invention may be carried out at the same time as steps (a) and (b), when these two steps are carried out together. However in preferred embodiments step (c) is carried out after step (a) and step (b) and thus step (c) preferably comprises contacting the surface of a cellulosic material which has been contacted with an amino compound and a source of metal ions with a composition comprising carbon dioxide and/or sulfur dioxide. Thus step (b) suitably involves contacting a cellulosic material carrying an amino compound and a metal ion with a composition comprising carbon dioxide or a source thereof.

When the composition used in step (c) comprises carbon dioxide this may be provided as carbon dioxide gas, as supercritical carbon dioxide or as solid carbon dioxide. In preferred embodiments the carbon dioxide is in gaseous form.

When the composition used in step (c) comprises sulfur dioxide this is preferably provided in gaseous form.

In preferred embodiments the gas used in step (c) is provided by a gaseous composition comprising at least 1 wt% carbon dioxide. Preferably composition contacted with the fibres of cellulosic material in step (c) is a gaseous composition comprising at least 5 wt% carbon dioxide, preferably at least 10 wt% carbon dioxide, preferably at least 20 wt% carbon dioxide.

In some embodiments step (c) involves treating the cellulosic fibres with a composition comprising at least 50 wt% carbon dioxide, for example at least 75 wt%, at least 90 wt% or at least 95 wt%.

Preferably the composition contacted with the cellulosic material in step (c) of the method of the present invention comprises carbon dioxide. In some embodiments the composition used in step (c) consists essentially of carbon dioxide.

In some embodiments the composition contacted with the cellulosic material comprises sulfur dioxide.

The composition may consist essentially of sulfur dioxide. Preferably it comprises one or more further components.

In some preferred embodiments the composition coniprises a carbon dioxide and sulfur dioxide. It may comprise other components, suitably other gaseous components, for example nitrogen.

In some preferred embodiments the composition contacted with the cellulosic material in step (c) comprises or is derived from the exhaust gas of a combustion system. For example the composition may be the flue or a power station, for example a wood-burning or coal-burning power station.

In some embodiments such exhaust gases may be concentrated or otherwise treated prior to contact with the fibres of cellulosic material.

In especially preferred embodiments the carbon dioxide and/or sulfur dioxide is provided by the exhaust of a fossil fuel burning engine, boiler, furnace or turbine. Thus the present invention may involve a method of capturing carbon from the atmosphere.

The composition used in step (c) may comprise at least 0.1 wt% sulfur dioxide, preferably at least 0.5 wt%, for example at least 1 wt%. It may comprise up to 20 wt% sulfur dioxide, for example up to 10 wt% or up to 7 wt%.

In one embodiments the composition contacted with the material composition in a gaseous composition comprising from 50 to 90 wt%, preferably 60 to 80 wt% nitrogen, from 10 to 40 wt%, preferably 20 to 30 wt% carbon dioxide and up to 20 wt%, preferably up to 10 wt% sulfur dioxide.

In some embodiments in step (c) a gaseous composition may be pumped into a vessel containing the material. In some embodiments the cellulosic material may have been dried following steps (a) and (b). Alternatively the material may still be damp.

Step (c) may be carried out at atmospheric pressure or it may be carried out at higher pressures. The skilled person will appreciate that when elevated pressures are used the contact times needed are generally shorter than when lower pressures are used.

In some embodiments the composition contacted with the material in step (c) may comprise carbon dioxide, sulfur dioxide or a mixture thereof along with a diluent or carrier. In some embodiments the composition may comprise only carbon dioxide, sulfur dioxide or a mixture thereof.

In some preferred embodiments the composition contacted with the material in step (c) consists essentially of carbon dioxide, i.e. it is provided from a source of carbon dioxide without the addition of a diluent or carrier. Minor impurities may be present.

In embodiments in which the cellulosic material is contacted with neat carbon dioxide gas this may be provided at a pressure of up to 40,000kPa, preferably from 100 to 5000 kPa. In some embodiments carbon dioxide may be delivered to the cellulosic material at ambient pressure, and preferably at ambient temperature. In preferred embodiments the carbon dioxide gas is at a supra-atmospheric pressure. In one embodiment a pressure of from 2000 to 4000 kPa, for example about 3000 kFa is used.

Preferably in step (c) the cellulosic material is contacted with carbon dioxide for a period of 01.

to 500 minutes, preferably to 200 minutes, more preferably to 100 minutes, suitably 5 to 60 minutes, for example 10 to 40 minutes.

The uptake of carbon dioxide and/or sulfur dioxide on the cellulosic material is preferably at least 1% omf, preferably at least 5% omf, more preferably at leas 10% omf, for example at least 15% omf.

The uptake of carbon dioxide and/or sulfur dioxide on the cellulosic material may be up to 100% omf, suitably up to 80% omf, preferably up to 60% omf, for example up to 50% omf or up to 40% omf, or up to 30% omf.

For the avoidance of doubt, the above amounts refer to the increase in weight of the treated cellulosic material, i.e. material that carries an amine and metal ions on the surface thereof.

It is an advantage of the present invention that relatively short contact times can be used in steps (a), (b) and (c) to achieve sufficient retention of carbon dioxide and/or sulfur dioxide on the surface of the cellulosic material. For example contact times of less than 1 hour, preferably less than 30 minutes can be used, in each of steps (a), (b) and (c).

Without wishing to be bound by theory it is believed that the carbon dioxide or sulfur dioxide interacts with the amino compound which is carried by the surface of the cellulosic fibres following step (a). The nature of this interaction is not fully understood. It is believed that there may be a polar interaction, a hydrogen bond may form or covalent bonding may occur.

Following step (c) the method may provide a cellulosic material in which carbon dioxide and/or sulfur dioxide is retained on the surface.

By retained on the surface it is meant that the carbon dioxide and/or sulfur dioxide is not labile, i.e. the molecules of carbon dioxide and/or sulfur dioxide are not merely associated with the surface and simply present in the same general area. Rather they are fixed at the surface.

They may be permanently or temporary fixed at the surface. Suitably the molecules of carbon dioxide and/or sulfur dioxide are not readily displaced from the surface of the cellulosic material without the application of an external stimulus.

The carbon dioxide and/or sulfur dioxide may be retained on the surface may physical and/or by chemical means. For example the carbon dioxide and/or sulfur dioxide may be retained by Van der Waals forces, hydrogen bonding or ionic forces. Preferably the carbon dioxide and/or sulfur dioxide is retained on the surface by means of a chemical bond, suitably a covalent bond.

Following step (c) the carbon dioxide may be permanently retained or bonded or it may be retained in a manner such that it could be released later in a subsequent application of the material. Hence the carbon dioxide or sulfur dioxide may be fixed to the surface of the material in a reversible or irreversible manner.

In some especially preferred embodiments the carbon dioxide is retained on the surface in a substantially irreversible manner. By this we mean that carbon dioxide is not readily released from the material under the normal conditions in which the material is used. Thus the treated cellulosic fibres are preferably stable at all humidities, at standard atmosphere pressure and at temperatures of between -30°C and 80°C, for example between -20°C and 60°C or between -10°C and 40°C. The treated cellulosic fibres are suitably weatherproof and carbon dioxide is not released under extremes of heat or cold or in very wet, very dry, windy or stormy environments.

The inventors have found that when using cellulosic material that has been contacted with a source of metal ions as well as an amino compound the carbon dioxide is more strongly retained on the surface than when only an amino compound is used, for example the treated material has been found to be more stable to an increase in temperature.

Step (d) of the method of the present invention involves admixing the cellulosic material with a polymer component.

Suitable polymeric components include the synthetic and natural polymers, and mixtures and copolymers thereof. Examples of suitable polymeric materials include polyalkylenes, for example polyethylene and polypropylene and polybutylene, polyamines, polyamides, polystyrenes, polyurethanes, polylactic acid, polyvinyl alcohol epoxy resins, ABA Poly(Acrylonitrile Butadiene Acrylate), ABS Poly(Acrylonitrile Butadiene Styrene), ECTFE Poly(Ethylene Chlorotrifluoroethylene), EEA Poly(Ethylene-Ethyl Acrylate), EP Epoxy; Epoxide, HDFE High Density Polyethylene, LDPE Low Density Polyethylene, LLDPE Linear Low Density Polyethylene, LMDPE Linear Medium Density Polyethylene, PA Polyacrylate, PAE Polyarylether, PCT Polycyclohexylenedimethylene Terephthalate, PET Polyethylene Terephthalate, PETE Polyethylene Terephthalate, PETe, PET Modified with CHDM, PEVA Poly(Ethylene Vinyl Acetate), PEX Cross-linked Polyethylene, PLA Polylactic Acid, PMMA Polymethylmethacrylate, PP Polypropylene, PS Polystyrene, PVAC Poly(Vinyl Acetate), PVAL Poly(Vinyl Alcohol), PVC Polyvinyl Chloride, PVCA Poly(Vinyl Chloride-Acetate), SAN Poly(Styrene Acrylonitrile), SB Styrene-Butadiene, and XLPE Cross-linked Polyethylene.

Preferably the polymeric material is an extrudable polymeric material. Preferably the material is injection mouldable. Especially preferred are thermoplastic polymers.

Preferred polymeric materials for use herein include polypropylene, polyethylene and copolymers of ethylene and propylene.

There may be intervening steps between step (c) and step (d) to ensure that the cellulosic material is in a suitable form. For example the cellulosic material may be dried, may be combed, or may be processed to provide strands or particles of an appropriate size.

In step (d) the strands or particles of cellulosic material may be mixed with the polymer component by any suitable means. For example they could be mixed by agitation and application of pressure. Preferably the fibres are mixed into the polymer component when it is in a semi-solid or preferably a liquid form.

Preferably in step (d) particles or strands of the cellulosic material are dispersed in a polymer melt.

By a polymer melt we mean to refer to a composition comprising one or more polymers in a flowable form. Suitably the composition is at a temperature above its melting point The treated particles or strands of cellulosic material may be dispersed in the polymeric melt by any suitable means. Preferably the treated particles or strands of cellulosic material are added to the melted polymer composition and the composition is agitated.

In one embodiment the treated particles or strands of cellulosic material may be poured into the feed hopper of an extruder in which the polymer melt is rotating.

In an alternative embodiment the treated particles or strands of cellulosic material may be compounded with molten polymer. The mixture may then be passed through a dye to produce pellets.

The amount of cellulosic material added to the polymer melt in step (d) may be up to 200% wt% of the polymer (i.e. weight of cellulosic material as a proportion of the weight of polymer in the melt). Suitably it may be up to 100 wt%, up to 75 wt% or up to 50 wt%. Preferably the weight of cellulosic fibres is at least 0.1 wt% of the weight of polymer, preferably at least 1 wt%, for example at least 2.5 wt% or at least 5 wt%.

The polymeric composition obtained following step (d) of the method of the second aspect is suitably a molten polymeric composition. This may be subsequently treated to provide a polymeric product.

According to a second aspect of the present invention there is provided a method of manufacturing a polymeric product, the method comprising preparing a polymeric composition according to steps (a), (b), (c), (d) of the method of the first aspect; and (e) processing the molten polymeric composition to form a polymeric product, Step (e) may comprise any suitable means by which a molten polymeric composition can be treated. Such methods will be known to the person skilled in the art. For example the molten composition may be extruded, injected, blown or cast. Suitable subsequent processing techniques depend on the nature of the polymeric product being made.

The polymeric composition provided by the method of the second aspect of the present invention may be used to make a wide variety of polymeric products. For example the composition may be used in the manufacture of plastic bottles and other packaging, or it may be used in the production of high performance polymeric materials. Suitable uses will be known to the person skilled in the art.

In some embodiments the present invention may be used to make ropes or pellets of polymeric material which can be stored and then remelted and subsequently processed to make useful products at a later date.

Products made using the method of the present invention comprise a lower mass of polymer material compared to equivalent products which do not include fibres. The treated cellulosic fibres suitably replace at least 0.1 wt% of the weight of polymer present in product: preferably at least 0.5 wt%, suitably at least 1 wt%, for example at least 5 wt% or at least 10 wt%.

The cellulosic fibres may replace up to 60 wt% of the polymer, preferably up to 50 wt%, suitably up to 40 wt%.

It has been surprisingly found that replacement of polymer material with a substantial portion of treated cellulosic fibres does not result in a deterioration of the properties of the polymeric material, and in some cases can improve the properties. Polymeric materials obtained by the present invention have also been show to have equivalent or improved properties compared to polymeric materials containing fibres of the prior art.

The replacement of polymer with fibres for reinforcement or to reduce polymer consumption is known. However the replacement of polymer with the treated cellulosic fibres significantly improves the environment profile of the polymeric compositions obtained by the method of the present invention. The invention allows for storage of carbon dioxide and/or sulfur dioxide in a useful polymeric prodouct.

By way of example only the preparation of materials according to the present invention will now be further described.

Example I

1kg of mechanically recovered wood pulp fibre was mixed with 500m1 of a composition comprising 2-amino-2-methyl-propanol (AMP) and 20 wt% water in a tumble mixer for 10 minutes at standard temperature and pressure. This mixture was then passed into a screw mixer through which pure CO2 at a pressure of 5 bar was passed. The material was contacted with the the CO2 in the screw mixer for 5 mins at stp. After 5 mins 200m1 of 50 wt% aqueous NaOH was added to the screw mixer with CO2 being continuously fed into the system for an additional 5 minutes.

The treated material was fed into an extruder along with polymer pellets. The resultant mixture was passed through a dye to give the polymeric composition of the invention. The comparative materials of the following examples were prepared by an analogous process.

Example 2

Samples of polymeric material were prepared using a method analogous to the method of

example 1.

In each case 30 wt% of fibres were incorporated into polypropylene. The ultiniate tensile strength of the fibres was measured and the results are shown in figure 1. Fibre

1 Carbon fibres 2 Glass fibres 3 Treated wood fibres having 30% omf NaOH, and 5% omf amine (AMP) 4 Treated wood fibres having 5% omf NaOH, and 30% omf amine (AMP)

Example 3

By a method analogous to example 1 polymeric compositions were prepared as follows: 1. Pure virgin polyethylene 2. Polyethylene comprising 30 wt% untreated wood fibres 3. Polyethylene comprising 30 wt% treated wood fibres having 30% omf NaGH, and 5% omf amine (AMP) 4. Polyethylene comprising 30 wt% treated wood fibres having 5% omf NaOH, and 30% omf amine (AMP) The tensile strength of the materials was measured and the results are shown in figure 2.

These show that the compositions according to the present invention show improved tensile strength.

Example 4

Polymer compositions were prepared comprising 30 wt% of the following fibres in an epoxy resin: 1. carbon fibre 2. glass fibre 3. cellulosic fibres comprising 30% omf NaOH and 5% omf amine (AMP) 4. cellulosic fibres comprising 5% omf NaOH and 30% omf amine (AMP) The Youngs modulus and ultimate yield of each of these materials was measure and is shown in figures 3 and 4 respectively.

Example 5

Polypropylene compositions were prepared comprising 30 wt% of the following: 1. wood fibres 2. glass fibres 3. wood fibres comprising 30% omf NaOH and 5% omf amine (AMP) 4. wood fibres comprising 5% omf NaOH and 30% omf amine (AMP) The tensile strength of each of these materials is shown in figure 5.

Claims

Claims 1. A method of preparing a polymeric composition, the method comprising the steps of: (a) contacting a cellulosic material with a composition comprising an amino compound; (b) contacting the cellulosic material with a composition comprising a source of metal ions; (c) contacting the cellulosic material with a composition comprising carbon dioxide or a mixture thereof; and (d) admixing the cellulosic material with a polymer component.
2. A method as claimed in claim 1, wherein the fibres are randomly dispersed throughout the cellulosic material, with a substantially even distribution.
3. A method as claimed in claim 1, wherein the cellulosic material is derived from plant C') fibres.

CV)
4. A method as claimed in any preceding claim where the cellulosic material is provided in 0 20 the form of strands or particles having an average size of less than 5 mm. aD
5. A method as claimed in any preceding claim, wherein step (a) comprises contacting the cellulosic material with a composition comprising ammonia or an amine.
6. A method as claimed in any preceding claim wherein the amino compound is providing in a solvent, preferably water.
7. A method as claimed in any preceding claim, where step (d) involves admixing the cellulosic material with a polymer component which is an extrudable thermoplastic polymeric material, in its molten form.
8. A method as claimed in any claim wherein the amount of cellulosic material added to the polymer melt in step (d) is at least 0.1 wt% and up to 200 wt% of the polymer (i.e. weight of cellulosic material as a proportion of the weight of polymer in the melt).
9. A method of manufacturing a polymeric product, the method comprising preparing a polymeric composition according to steps (a), (b), (c), (d) of the method of any preceding claim, and (e) processing the molten polymeric composition to form a polymeric product.