CN100348655C - Preparation of polymer composite material from halloysite nanometer tube - Google Patents

Abstract

The present invention relates to a method for preparing polymer composite material from halloysite nanometer tubes, which comprises the steps: halloysite nanometer tubes are mixed with polymer according to the weight ratio of 40 to 99: 0.5 to 60, and are homogeneously dispersed in a polymeric matrix; then, polymer composite material is obtained through forming. The halloysite nanometer tubes are natural clay minerals which are in a micro tubular structure formed by twisting silicate sheet layers under the natural condition. The polymer is one or more than one of thermoplastic plastic, thermosetting plastic and rubber. The polymer nanometer composite material which has obviously enhanced mechanical performance and flame retardant performance is formed. The present invention overcomes the defect that the existing nanometer fillers are not easily dispersed, and fillers are cheap and are easily obtained without dust pollution.

Description

The method that halloysite nanotube is used for preparing polymer composite material

technical field

The invention relates to the technical field of polymer composite materials, in particular to a method for preparing a polymer composite material using halloysite nanotubes.

Background technique

The main feature of nanocomposites (Nanocmposites) is that one or more components in the composite system are uniformly dispersed in the matrix of another component with nanometer size (≤100nm) in at least one dimension, sometimes called hybrid materials or heterogeneous materials. Chemical materials (Hybrid Materials). Organic/inorganic nanocomposites composed of polymers and certain inorganic substances, the polymers form a uniform and firm combination with nanoscale inorganic substances, the surface area of nanoscale is large, and the distance between phases is small, and there is a special interaction. Therefore, its performance is significantly different from that of the corresponding macroscopic or micron-scale composite materials (for example, traditional inorganic filler-filled modified polymers), showing completely new properties or functions.

Combining modifiers and fillers with nanometer size with polymers is the main method to prepare polymer nanocomposites.

The fillers currently used in polymer nanocomposites can be divided into two categories, namely natural nanofillers and synthetic nanofillers.

Natural nanoscale fillers refer to structures containing nanoscale structural units. In the preparation of polymers, nanoscale structural units can be dispersed in polymers to form polymer nanocomposites. The most widely used materials of this type are various layered silicates, such as montmorillonite and kaolin. The main difficulty in the application of this type of nanoscale filler is that it needs to overcome the interlayer ionic bond to form nanoscale dispersion, so the preparation process is often difficult and the dispersion effect is not ideal.

Synthetic nano-fillers include various synthetic inorganic filler powders, such as nano-calcium carbonate, nano-silica, nano-titanium dioxide, and nano-magnesium hydroxide. For various synthetic nanopowders, there are many shortcomings that are difficult to overcome. Firstly, the preparation process of nanopowder is relatively complicated, and the cost has been high; secondly, the bulk density of nanopowder is extremely low, which leads to agglomeration easily and serious dust pollution; furthermore, agglomeration of nanopowder makes surface modification difficult , further making its dispersion difficult.

Contents of the invention

The purpose of the present invention is to provide a kind of method that halloysite nanotube is used for preparing polymer composite material in view of the defect existing in the prior art, and form the polymer nanocomposite material with obviously improved mechanical property and flame retardant performance; Overcome the present invention It has the disadvantage of difficulty in dispersing nano fillers, and the fillers are cheap and easy to obtain without dust pollution.

The method that the halloysite nanotube of the present invention is used to prepare the polymer composite material comprises: the halloysite nanotube and the polymer are mixed by 1: 10, 1: 100, 40: 100 or 1: 5 weight ratio, make halloysite The stone nanotubes are evenly dispersed in the polymer matrix, and then molded to obtain polymer composite products.

The halloysite nanotube is a natural clay mineral, a microtubular structure formed by silicate sheets curled under natural conditions, with the same 1:1 SiO ₂ /Al ₂ O ₃ ratio, the sheet The layer structure curls into a barrel structure with SiO ₂ in the outer layer and Al ₂ O ₃ in the inner layer. Generally, the halloysite nanotube is formed by curling multiple sheets, the outer diameter of the tube is about 10-50nm, the inner diameter is about 5-20nm, and the length is about 2-40μm, so it is a natural multi-walled microtube. When the pH value is between 4 and 9, the surface zeta potential of halloysite nanotubes varies between -20 and -50mV. When the pH is less than 6, there is a weak negative charge inside the tube. The distance between adjacent pipe walls (interlayer distance) has two values of 7.3 angstroms and 10.1 angstroms according to whether it contains water or not. It is worth noting that halloysite is not ion-exchangeable or expansive like other clay minerals due to its complete coiling into tubes. In terms of chemical properties, the surface layer of halloysite nanotubes has very similar surface properties to SiO ₂ , while the inner layer properties are similar to Al ₂ O ₃ .

The polymer is one or more of thermoplastics, thermosetting plastics and rubber.

The thermoplastics include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-butadiene-styrene terpolymer (ABS), polymethyl One or more mixtures of general-purpose plastics such as methyl acrylate (PMMA) and engineering plastics such as polyamide (nylon), thermoplastic polyester (PET and PBT), polyoxymethylene (POM), polycarbonate (PC), etc. ;

Described thermosetting resin comprises epoxy resin (EP), unsaturated polyester resin (UP), allyl resin, amino resin, thermosetting polyimide resin, cyanate resin, bismaleimide resin (BMIs ), phenolic resin, thermosetting polyurethane (PU), etc. or one or more mixtures;

The rubber includes natural rubber (NR) and various synthetic rubbers, such as styrene-butadiene rubber (SBR), polyisoprene (IR), butyl rubber (IIR), polybutadiene rubber (PBR), acrylonitrile -Butadiene copolymer (NBR), and a mixture of one or more of various thermoplastic elastomers, etc.

Mixing and molding of halloysite nanotubes and polymers can adopt common mixing equipment and molding equipment in the prior art. For example, twin-screw extruders, internal mixers or other mixing equipment are used for thermoplastic polymers for melting and mixing, and extruders or injection machines are used for molding; mixing equipment for thermosetting plastic polymers includes grinders and mixers, etc.; the mixing equipment used for rubber polymers includes various rubber mixing equipment.

In order to further improve the compatibility of halloysite nanotubes and thermoplastics, enhance the bonding between halloysite nanotubes and polymer matrix, and fully disperse halloysite nanotubes in polymer matrix, the present invention can also The halloysite nanotube material is surface treated with a surface modifier, and the surface treatment can adopt a common method in the field, and the amount of the surface modifier accounts for 0.5-5% by weight of the halloysite nanotube.

Described surface modifier can adopt general surface modifier in the art, and inventor finds that the optimum surface modifier that the present invention adopts comprises three classes through creative exploration, wherein

(1) γ-aminopropyltriethoxysilane, γ-epoxypropyltriethoxysilane, vinylphenylethylenediaminepropyltrimethoxysilane monohydrochloride, γ-methyl Various organosilanes such as acryloxypropyltrimethoxysilane, titanate coupling agent. Such surface modifiers can be directly added to the halloysite nanotubes or the mixed system of halloysite nanotubes and polymers.

(2) Vinyl monomers for halloysite nanotube grafting, including maleic anhydride (MAH) and its esters, fumaric anhydride (FAH) and its esters, acrylic acid (AA), methacrylic acid (MA) , long-chain acrylate or methacrylate, β-hydroxypropyl acrylate (HPA), β-hydroxyethyl methacrylate (HEMA), acrylamide, divinylbenzene, ethylene glycol dimethacrylate, etc.; Such surface modifiers may need to be grafted with halloysite nanotubes under thermally or photoinitiated conditions.

(3) Macromolecular coupling agents used to improve the interface between polymers and halloysite nanotubes, including polypropylene grafted maleic anhydride and polyethylene grafted maleic anhydride, etc. Such surface modifiers can be directly added to the mixed system of halloysite nanotubes and polymers.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The halloysite nanotubes used in the present invention are low in cost and rich in resources, which can greatly reduce the production cost of polymer composite materials.

2. The polymer composite material prepared by the present invention can be used in the manufacture of various thermoplastics, thermosetting plastics and vulcanized rubber products, and can also be used in other polymer fields such as adhesives and coatings, and has broad application prospects.

3. The mechanical properties such as impact strength, flexural modulus and flexural strength of the thermoplastic and thermosetting polymer composite materials prepared by the present invention are significantly improved, and the thermal decomposition temperature and the flame retardancy of the polymer are also significantly improved.

4. The polymer composite material prepared by the present invention is used in the field of rubber, which can significantly improve the modulus, tensile strength, elongation at break, permanent deformation, tear strength and hardness of the rubber, and can also improve the crosslinking of the rubber. Density, aging properties, dynamic mechanical properties and processing properties.

Detailed ways

Example 1

Step 1: Dissolve 1 gram of γ-aminopropyltriethoxysilane in a small amount of acetone, and then evenly spray it on the halloysite nanotube material. After the acetone volatilizes naturally, the modified halloysite nanotube The tubes were dried at 80°C for 4 hours.

Step 2: Mix 100 grams of surface-modified halloysite nanotubes with 1000 grams of polyethylene resin, and then use a twin-screw extruder to carry out melt blending and granulation.

The third step: injecting the mixture obtained in the second step with an injection machine to obtain a polyethylene/halloysite nanotube composite material product.

Observing the obtained composite material with a scanning electron microscope and a transmission electron microscope, it is found that the halloysite nanotubes are uniformly dispersed in the polyethylene matrix at a nanometer scale, indicating that the polymer/halloysite nanotube composite material has been prepared.

Example 2

Step 1: Dissolve 1 gram of vinylphenylethylenediaminepropyltrimethoxysilane monohydrochloride in a small amount of ethanol, hydrolyze it for 3 minutes, and spray it evenly in halloysite nanotubes. After the ethanol volatilizes naturally Then the modified halloysite nanotubes were dried at 90° C. for 5 hours.

Step 2: Mix 1 g of surface-modified halloysite nanotubes with 100 g of epoxy resin and stir at room temperature for 2 hours.

The third step: 15 grams of m-xylylenediamine was added to the mixture, stirred evenly, degassed, and then poured into the test mold.

Step 4: After parking at room temperature for 24 hours, post-cure at 70° C. for one hour to prepare epoxy resin/halloysite nanotube composite material.

Observing the obtained composite material with a scanning electron microscope and a transmission electron microscope, it is found that the halloysite nanotubes are uniformly dispersed in the epoxy resin at a nanometer scale, indicating that the polymer/halloysite nanotube composite material has been prepared.

Example 3

Step 1: Add 10 grams of the modified halloysite nanotubes obtained in Example 2 into an appropriate amount of acetone, then add 3 grams of isooctyl acrylate and 0.1 grams of photoinitiator, and stir for 10 minutes. Then place it in a tray, wait for the acetone to volatilize naturally, dry it, and treat it with ultraviolet light for a certain period of time to prepare the modified halloysite nanotube.

Step 2: Use a two-roll mill to mix natural rubber (NR), compounding agents, and modified halloysite nanotube materials. After the mixed rubber is left overnight, use a flat vulcanizer to vulcanize and shape it. The vulcanization conditions are: 143°C× The natural rubber/halloysite nanocomposite was prepared with positive vulcanization time.

Basic formula of compound rubber: natural rubber 100, modified halloysite nanotube 40, stearic acid 2, ZnO4, promotion CZ 1.5, promotion DM 0.5, sulfur 1.5.

Observing the obtained composite material with scanning electron microscope and transmission electron microscope, it is found that the halloysite nanotubes are evenly dispersed in the natural rubber matrix at the scale of tens of nanometers, indicating that the natural rubber/halloysite nanotube composite material has been prepared.

Table 1 has listed the influence of halloysite modification and content on the crosslinking density of natural rubber vulcanizate, as can be seen from the table, the crosslinking density of natural rubber is only 0.194, and adding 40wt% unmodified halloysite After adding nanotubes, the crosslinking density of the system increased, while the crosslinking density of the system added with 40wt% modified halloysite nanotubes was greatly increased, and the 0.194 increased to 0.310, indicating that the modifier chemically combines with the surface of halloysite and reacts chemically with the double bond of rubber to form a good cross-linking network, which makes halloysite play the role of physical cross-linking point, thus greatly The crosslink density of the system is increased.

Table 1 Effect of the modification and content of hallite on the crosslinking density of natural rubber vulcanizate

sample natural rubber NR/ Halloysite nanotubes (100/40) NR/modified halloysite nanotubes (100/40) Crosslink density 0.194 0.220 0.310

Table 2 is the physical and mechanical properties of natural rubber/modified halloysite nanotube composites. From Table 2, it can be seen that the modified halloysite nanotubes have a good reinforcing effect on natural rubber, which is due to the tubular structure of halloysite nanotubes forming a denser network structure than the traditional filling network. Therefore, the halloysite nanotube filling system greatly reduces the permanent deformation and improves the tensile strength. This is mainly because the modifier chemically combines with the silanol groups on the surface of halloysite to form a stable bond, and a good cross-linked network is formed when the system is vulcanized, which improves the interface between halloysite nanotubes and rubber Force to form natural rubber/modified halloysite nanocomposites with better physical and mechanical properties.

Table 2 Physical and mechanical properties of natural rubber/modified halloysite nanotube composites

mechanical properties NR NR/modified halloysite nanotubes (10wt%) NR/modified halloysite nanotubes (30wt%) NR/carbon black (50 parts semi-reinforced) 300% modulus stress, MPa tensile strength, MPa elongation at break, % tensile set, % hardness (Shore A), degree 1.724.77301242 6.632.06302558 7.226.55503763 9.627.95603865

Example 4

Step 1: Dissolve 1 gram of bis-γ-methacryloxypropyltrimethoxysilane in a small amount of acetone, and then evenly spray it on the halloysite nanotube material, and then apply the modified halloysite nanotube material The tubes were dried at 80°C for 4 hours.

Step 2: Mix 200 grams of surface-modified halloysite nanotubes with 1000 grams of polypropylene resin, and then use a twin-screw extruder to carry out melt blending and granulation.

The third step: injecting the mixture obtained in the second step with an injection machine to prepare a polypropylene/halloysite nanotube composite material.

Observing the obtained composite material with a scanning electron microscope and a transmission electron microscope, it is found that the halloysite nanotubes are uniformly dispersed in the polypropylene matrix at a nanometer scale, indicating that the polymer/halloysite nanotube composite material has been prepared.

Table 3 lists some mechanical properties of polypropylene/halloysite composites. It can be seen from the table that the impact strength, tensile strength, flexural modulus and flexural strength of polypropylene/halloysite nanocomposites are all improved in different ranges compared with pure polypropylene. The impact strength, flexural strength and flexural modulus of polypropylene nanocomposites filled with rockite nanotubes are greatly improved.

Table 3 Effect of polypropylene/halloysite composites on mechanical properties

modifier Impact strength (KJ/m ² ) Tensile strength (MPa) Flexural modulus (MPa) Bending strength (MPa) Pure PP halloysite nanotubes modified halloysite nanotubes 4.066.368.36 32.432.034.5 1183.001254.671592.55 40.6541.9646.86

Example 5

Step 1: Dissolve 1 gram of β-hydroxypropyl acrylate and 0.5 gram of toluene diisocyanate mixed surface modifier in a small amount of acetone, and then evenly spray it on 100 grams of halloysite nanotube material. After the acetone volatilizes naturally The modified halloysite nanotubes were dried at 80°C for 4 hours.

The second step: mixing the surface-modified halloysite nanotubes with polypropylene resin, and then using a twin-screw extruder to perform melt blending and granulation.

The third step: injecting the mixture obtained in the second step with an injection machine to prepare a polypropylene/halloysite nanotube composite material.

Table 4 lists the thermal degradation temperatures of various polypropylene/halloysite nanotube composites.

Table 4 Thermal degradation temperature of various polypropylene/halloysite nanotube composites

composition Weight loss 5% temperature (°C)  10% weight loss temperature (°C) Maximum weight loss rate temperature (°C) Pure PP unmodified halloysite nanotube 10% unmodified halloysite nanotube 30% modified halloysite nanotube 10% modified HNT 20 modified HNT 30% 384415381445433433 399430400461445447 451460440487474478

It can be seen from Table 4 that the temperature at which PP loses 5% of its weight can be increased by more than 60°C, indicating that the thermal stability is greatly improved.

Claims (8)

1, a kind of method that halloysite nanotube is used for preparing polymer composite material, it is characterized in that halloysite nanotube mixes with polymer by the weight ratio of 1: 10, 1: 100, 40: 100 or 1: 5, The halloysite nanotubes are uniformly dispersed in the polymer matrix, and then shaped to obtain polymer composite products; the halloysite nanotubes are a kind of natural clay minerals, which are formed by curling silicate sheets under natural conditions. The formed microtubular structure; the polymer is one or more of thermoplastics, thermosetting plastics, and rubber. 2. The method according to claim 1, wherein said thermoplastic comprises polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylonitrile-butadiene-styrene terpolymer, polymethyl One or more mixtures of methyl acrylate, polyamide, thermoplastic polyester, polyoxymethylene, and polycarbonate. 3. The method according to claim 1, wherein the thermosetting resin comprises epoxy resin, unsaturated polyester resin, allyl resin, amino resin, thermosetting polyimide resin, cyanate resin, bis One or more mixtures of maleimide resin, phenolic resin, and thermosetting polyurethane. 4. The method according to claim 1, wherein the rubber comprises one of styrene-butadiene rubber, polyisoprene, butyl rubber, polybutadiene rubber, and acrylonitrile-butadiene copolymer or a variety of mixtures. 5. The method according to any one of claims 1-4, characterized in that the halloysite nanotubes are surface treated with a surface modifier, and the amount of the surface modifier accounts for 0.5 to 5% by weight of the halloysite nanotubes . 6. The method according to claim 5, characterized in that the surface modifier is γ-aminopropyltriethoxysilane, γ-epoxypropyltriethoxysilane, vinylphenylethylenedi Aminopropyltrimethoxysilane monohydrochloride, γ-methacryloxypropyltrimethoxysilane or titanate coupling agent. 7. The method according to claim 5, wherein the surface modifier is maleic anhydride and its esters, fumaric anhydride and its esters, acrylic acid, methacrylic acid, long-chain acrylates, methacrylates , one or more of β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, acrylamide, divinylbenzene, and ethylene glycol dimethacrylate. 8. The method according to claim 5, characterized in that said surface modifier is polypropylene grafted maleic anhydride or polyethylene grafted maleic anhydride.