Method for forming nanocomposite materials
A method for forming a nanocomposite material includes introducing a nanofiller material having polar end groups into an extruder having a polymeric material therein. An unsaturated shielding material is introduced into the extruder. The unsaturated shielding material reacts with the polar end groups, thereby forming a shielded nanofiller material. The shielded nanofiller material is grafted to the polymeric material, thereby forming the nanocomposite material. The nanofiller material therein is substantially exfoliated, and the nanocomposite material exhibits enhanced physical properties.
1. A method for forming a nanocomposite material, the method comprising the steps of:
introducing a nanofiller material having polar end groups into an extruder having a polymeric material therein, the introducing being downstream of an area of the extruder wherein the polymeric material has been substantially melted and mixed;
introducing an unsaturated shielding material into the extruder having the polymeric material therein, the introducing being downstream of an area of the extruder wherein the polymeric material has been substantially melted and mixed;
causing the unsaturated shielding material to chemically react with at least some of the polar end groups, thereby forming a shielded nanofiller material; and
grafting the shielded nanofiller material to the polymeric material, thereby forming the nanocomposite material;
wherein causing the unsaturated shielding material to react and grafting the shielded nanofiller material to the polymeric material are controlled by monitoring concentration and temperature; and
wherein the nanofiller material is substantially exfoliated and wherein the nanocomposite material exhibits enhanced physical properties.
2. The method as defined in claim 1 wherein the polymeric material comprises thermoplastic materials.
3. The method as defined in claim 2 wherein the thermoplastic materials comprise at least one of polypropylenes, polyethylenes, elastomers, impact copolymers thereof, polystyrene, polyethyleneterephthalate, polymethylmethacrylate, polycarbonate, polyurethane, poly(acrylonitrile-co-butadiene-co-styrene) (ABS), poly(acrylonitrile-co-styrene-co-acrylate) (ASA), poly(styrene-co-butadiene-co-styrene) (SBS), polycarbonate-poly(acrylonitrile-co-butadiene-co-styrene) (PC-ABS), and mixtures thereof.
4. The method as defined in claim 2 wherein the thermoplastic materials comprise one of thermoplastic olefins including at least one of polypropylene homopolymers, impact modified polypropylene, ethylene propylene elastomers, and mixtures thereof.
5. The method as defined in claim 1 wherein the nanofiller material comprises a clay material which is at least one of smectite, hectorite, montmorillonite, bentonite, beidelite, saponite, stevensite, sauconite, nontronite, illite, and mixtures thereof.
6. The method as defined in claim 1 wherein the unsaturated shielding material comprises at least one of acid chlorides having at least one free radical polymerizeable alkene functional group, carboxylic acids having at least one free radical polymerizeable alkene functional group, anhydrides having at least one free radical polymerizeable alkene functional group, and mixtures thereof.
7. The method as defined in claim 1 , further comprising mixing the nanofiller material with an unsaturated monomer prior to introduction into the extruder.
8. The method as defined in claim 1 wherein grafting the shielded nanofiller material to the polymeric material is accomplished by introducing an initiator into the extruder downstream of an area of the extruder where the shielded nanofiller material is formed.
9. The method as defined in claim 8 wherein the initiator is a free radical initiator.
10. The method as defined in claim 9 wherein the free radical initiator comprises at least one of peroxides, peresters, organic polyoxides, azo compounds, and combinations thereof.
11. The method as defined in claim 8 wherein at least some of the unsaturated shielding material is introduced into the extruder with the initiator.
12. The method as defined in claim 9 wherein the unsaturated shielding material comprises maleic anhydride, and wherein grafting the shielded nanofiller material results in the reaction of excess maleic anhydride with unsaturated groups bonded to the polar groups of the nanofiller material, and propagation of maleic anhydride through free radical initiation.
13. A method for forming a nanocomposite material, the method comprising the steps of:
introducing a nanofiller material having polar end groups and an unsaturated shielding material substantially simultaneously into an extruder having a polymeric material therein, the introducing being downstream of an area of the extruder wherein the polymeric material has been substantially melted and mixed;
causing the unsaturated shielding material to chemically react with at least some of the polar end groups, thereby forming a shielded nanofiller material; and
introducing an initiator into the extruder downstream of an area of the extruder where the shielded nanofiller material is formed, thereby grafting the shielded nanofiller material to the polymeric material and forming the nanocomposite material;
wherein the nanofiller material is substantially exfoliated and wherein the nanocomposite material exhibits enhanced physical properties.
14. The method as defined in claim 13 wherein the unsaturated shielding material comprises at least one of acrylic acids, styrylic acids, maleic anhydride, acrylic acid chlorides, styrylic acid chlorides, silanes having at least one unsaturated organic group, and mixtures thereof.
15. The method as defined in claim 13 wherein at least some of the unsaturated shielding material is introduced into the extruder substantially simultaneously with the initiator.
16. The method as defined in claim 13 the initiator is a free radical initiator comprising at least one of peroxides, peresters, organic polyoxides, azo compounds, and combinations thereof.
17. A method for exfoliating a nanofiller material in a nanocomposite material, the method comprising the steps of:
introducing a mixture of a nanofiller material having polar end groups and an unsaturated shielding material into an extruder having a polymeric material therein, the introducing being downstream of an area of the extruder wherein the polymeric material has been substantially melted and mixed;
causing the unsaturated shielding material to chemically react with the polar end groups, wherein the nanofiller material is substantially exfoliated and a shielded nanofiller material is formed; and
grafting the shielded nanofiller material to the polymeric material to form the nanocomposite material;
wherein the nanocomposite material exhibits enhanced physical properties.
18. The method as defined in claim 17 wherein grafting the shielded nanofiller material to the polymeric material is accomplished by introducing an initiator into the extruder downstream of an area of the extruder where the shielded nanofiller material is formed.
19. The method as defined in claim 18 wherein the nanocomposite material is adapted for use as at least one of an automotive interior body material and an automotive exterior body material.
20. A nanocomposite material formed by the method as defined in claim 1 .