Preparation of rubber and macromolecular compatibilizer and application of macromolecular compatibilizer in NR/EPDM alloy elastomer
阅读说明：本技术 一种橡胶并用大分子增容剂的制备及其在nr/epdm合金弹性体中的应用 (Preparation of rubber and macromolecular compatibilizer and application of macromolecular compatibilizer in NR/EPDM alloy elastomer ) 是由 夏茹 钱坤 钱家盛 章于川 李方山 吴兵 曹明 方胜阳 伍斌 于 2019-12-06 设计创作，主要内容包括：本发明公开了一种橡胶并用大分子增容剂的制备及其在NR/EPDM合金弹性体中的应用,其中橡胶并用大分子增容剂是通过高温热力学接枝法在天然橡胶NR上接枝COD支链得到。本发明大分子增容剂的主链是NR的结构,因此主链是与NR完全相容的,接枝的支链结构又与EPDM结构相似,所以支链与EPDM几乎完全相容。因此,当把这种双亲性结构的增容剂NR-g-COD按照一定的比例添加到NR与EPDM的共混胶中,能够有效地降低EPDM分散相的相畴尺寸,增大了NR与EPDM两相接触的界面面积,强化了NR橡胶与EPDM橡胶动力学的相容性,从而提高了共混胶的物理机械性能。(The invention discloses a preparation method of a rubber-used macromolecular compatibilizer and application of the rubber-used macromolecular compatibilizer in an NR/EPDM alloy elastomer, wherein the rubber-used macromolecular compatibilizer is obtained by grafting a COD branched chain on natural rubber NR by a high-temperature thermodynamic grafting method. The main chain of the macromolecular compatibilizer is of an NR structure, so that the main chain is completely compatible with NR, and the grafted branched chain structure is similar to an EPDM structure, so that the branched chain is almost completely compatible with EPDM. Therefore, when the compatibilizer NR-g-COD with the amphiphilic structure is added into the blend rubber of NR and EPDM according to a certain proportion, the domain size of the disperse phase of the EPDM can be effectively reduced, the contact interface area of the NR and the EPDM is increased, the dynamic compatibility of the NR rubber and the EPDM rubber is enhanced, and the physical and mechanical properties of the blend rubber are improved.)
1. A preparation method of a macromolecular compatibilizer used for rubber is characterized by comprising the following steps: is obtained by grafting a COD branched chain on natural rubber NR by a high-temperature thermodynamic grafting method.
2. The method of claim 1, comprising the steps of:
step 1: firstly, raw natural rubber and a grafting agent A are put into an open mill for plastication, and the NR Mooney viscosity ML is achieved through multiple thin passes(1+4)125℃<25, adding the plasticated mixture, the lubricant B and the initiator C into an open mill once, adjusting the roller distance to 2mm, keeping the roller temperature at 30-40 ℃, and then performing triangular bag packing for a plurality of times, and thinly passing through and discharging sheets to obtain a masterbatch M;
step 2: and (2) shearing the master batch M obtained in the step (1) into fragments with the same size, adding the fragments into an internal mixer, setting the temperature to be 50-200 ℃, setting the rotating speed to be 30-70rad/min, and carrying out internal mixing for 3-30min to obtain the macromolecular compatibilizer product.
3. The method of claim 2, wherein:
in the step 1, the grafting agent A is COD, and the addition amount of the grafting agent A is 1-25% of the mass of the raw rubber of the natural rubber.
4. The production method according to claim 3, characterized in that:
the addition amount of the grafting agent A is 10-15% of the mass of the raw rubber of the natural rubber.
5. The method of claim 2, wherein:
in the step 1, the lubricant B is one or more of stearic acid, butyl stearate and oleamide, and the addition amount of the lubricant B is 0.1-5% of the mass of the raw natural rubber.
6. The method of claim 2, wherein:
in the step 1, the initiator C is one or more of di-tert-butyl peroxide, dibenzoyl peroxide, benzoyl peroxide and lauroyl peroxide, and the addition amount of the initiator C is 0.01-2% of the mass of the raw rubber of the natural rubber.
7. The method of claim 2, wherein:
in the step 1, the crude rubber of the natural rubber is Malaysia STR10CV, and the Mooney viscosity is ML(1+4)125℃65。
8. Use of a rubber prepared according to any one of claims 1 to 7 in combination with a macromolecular compatibilizer, characterized in that: is used as a compatibilizer when NR and EPDM are blended and used to improve the compatibility of natural rubber and ethylene propylene diene monomer.
9. Use according to claim 8, characterized in that:
the addition proportion of the macromolecular compatibilizer is 1-15%.
10. Use according to claim 8, characterized in that:
the mass ratio of NR and EPDM blend is 80:20-50: 50.
Technical Field
The invention relates to a preparation method of a macromolecular compatibilizer used for rubber and application thereof in NR/EPDM alloy elastomers. The macromolecular compatibilizer can be used as a compatibilizer in the blending of natural rubber NR and ethylene propylene diene monomer EPDM and the production of NR/EPDM alloy elastomers so as to improve the dynamic compatibility of the natural rubber and the ethylene propylene diene monomer.
Background
The main chain of Natural Rubber (NR) is a straight chain formed by 1,4 addition polymerization of cis-1, 3-isoprene. Each structural unit of the rubber has a double bond and a nonpolar side methyl group with small steric hindrance, so the macromolecular chain structure of NR is regular, nonpolar, good in flexibility, low in glass transition temperature Tg and easy to crystallize during stretching, so that the NR vulcanized rubber has excellent physical and mechanical comprehensive properties such as rebound resilience, electric insulation, bending fatigue resistance and the like, is widely applied, and is mainly used for manufacturing rubber tires of vehicles, various rubber parts for shock absorption and noise reduction and other products. However, NR contains a large number of unsaturated double bonds in its molecular chain and is susceptible to O in the air2And ozone in the environment O3Attack, particularly under thermal and Ultraviolet (UV) conditions, is highly susceptible to radical thermal oxidative aging and ultraviolet light oxidative aging reactions, and is therefore heat resistantOxygen aging resistance and weather aging resistance are poor, and in addition, due to the non-polarity of the oxygen aging resistance and weather aging resistance, the oxygen aging resistance and weather aging resistance are not resistant to fuel oil and non-polar solvents. These disadvantages limit the scope of application of NR, for example pure NR cannot be used to manufacture automotive parts operating in high temperature, ozone and fuel environments, in order to avoid safety hazards during driving.
Ethylene-propylene-diene monomer (EPDM) is a general purpose rubber made from random copolymerization of ethylene, propylene and a third monomer, the main chain of which is fully saturated, but contains a small number of reactive double bonds on the side groups of the third monomer for cross-linking and vulcanization. EPDM is a non-polar rubber with excellent resistance to thermo-oxidative aging, weathering, insulation, water and corrosion, and mechanical properties. Due to the excellent performance, the high-performance epoxy resin composition has wide application in the aspects of building materials, electric cables, waterproofing, automobile part manufacturing and the like. However, EPDM has poor self-adhesion and mutual adhesion, resulting in poor processability and limited application range.
According to the principle of polymer blending modification, NR and EPDM can be blended through a proper processing method and a proper technological means, so that the good physical and mechanical properties and the processing property of NR are combined with the heat resistance and weather aging resistance of EPDM, and the application fields of the two rubbers are further expanded. However, the dynamic compatibility of NR and EPDM is not good, the vulcanization speed of NR and EPDM is greatly different, and the blend of NR and EPDM only has obvious phase separation phenomenon during vulcanization through simple mechanical blending, so that the physical and mechanical properties of the blended vulcanizate are poor. How to develop a proper compatibilizer through polymer design and enable NR and EPDM to be uniformly dispersed under the action of mechanical shearing force to form a stable microphase separation multiphase condensed state structure with the EPDM as a dispersed phase and the NR as a continuous phase, so that a synergistic effect is generated between the NR and the EPDM and respective excellent performances are exerted, and the technical problem to be solved by the invention is solved.
Disclosure of Invention
The invention aims to provide a preparation method of a rubber and macromolecular compatibilizer and application of the rubber and the macromolecular compatibilizer in NR/EPDM alloy elastomers. The macromolecular compatibilizer NR-g-COD of the invention can enhance the kinetic compatibility of NR and EPDM when blended.
The macromolecular compatibilizer for blending rubber is obtained by grafting a COD (8012-resistant German Eupatorium fortunei) branched chain on natural rubber NR by a high-temperature thermodynamic grafting method. COD is a product obtained by ring-opening metathesis polymerization (ROMP) of cyclooctene, the main chain of the product is straight chain and contains unsaturated double bonds, the molecular weight is about 9 ten thousand, and the glass transition temperature is low. By plasticating the molecular chain, the COD macromolecular chain is broken into a molecular chain with double bonds at the end group, and under the action of high-temperature high shear force and an initiator, the double bonds at the end group in the COD molecular chain and the double bonds in the NR molecular chain can generate graft reaction. The main chain of the compatibilizer is of an NR structure, so that the main chain is completely compatible with NR, and the grafted branched chain structure is similar to an EPDM structure, so that the branched chain is almost completely compatible with EPDM. Therefore, when the compatibilizer NR-g-COD with the amphiphilic structure is added into the blend rubber of NR and EPDM according to a certain proportion, the domain size of the disperse phase of the EPDM can be effectively reduced, the contact interface area of the NR and the EPDM is increased, the dynamic compatibility of the NR rubber and the EPDM rubber is enhanced, and the physical and mechanical properties of the blend rubber are improved.
The preparation of the rubber combined macromolecular compatibilizer NR-g-COD comprises the following steps:
step 1: firstly, natural rubber crude rubber (NR crude rubber) and a grafting agent A are plasticated in an open mill, and the NR Mooney viscosity ML is achieved by multiple thin passes(1+4)125℃<25, adding the plasticated mixture, the lubricant B and the initiator C into an open mill once, adjusting the roller distance to 2mm, keeping the roller temperature at 30-40 ℃, and then performing triangular bag packing for a plurality of times, and thinly passing through and discharging sheets to obtain a masterbatch M;
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Step 2: and (2) shearing the master batch M obtained in the step (1) into fragments with the same size, adding the fragments into an internal mixer, setting the temperature to be 50-200 ℃, setting the rotating speed to be 30-70rad/min, and carrying out internal mixing for 3-30min to obtain the macromolecular compatibilizer product.
In the invention, the high-temperature mechanical grafting reaction of the natural rubber and the grafting agent A is the key for preparing the compatibilizer. The lubricant B is added to facilitate the processing of the natural rubber, so that the grafting agent A is better dispersed in the natural rubber, and the grafting reaction is initiated by the initiator.
The rubber prepared by the invention is used together with a macromolecular compatibilizer NR-g-COD, and is used as a compatibilizer when NR and EPDM are mixed together to improve the compatibility of natural rubber and ethylene propylene diene monomer.
Wherein the addition proportion of the macromolecular compatibilizer is 1-15 percent; the mass ratio of NR and EPDM blend is 80:20-50: 50.
Compared with the prior art, the invention has the beneficial effects that:
1. the raw material cost is low, the preparation process is simple and easy to operate;
2. the macromolecular compatibilizer prepared by the invention has compatibilization effect on the blending of NR and EPDM. The compatibilizer of the invention is added into the blended rubber, so that rubber vulcanized products with better physical and mechanical properties and thermal air aging resistance can be prepared.
3. The grafting agent selected by the macromolecular compatibilizer prepared by the invention is COD, and compared with the existing product, the macromolecular compatibilizer has the advantages of regularly arranged polymer skeleton structure, high proportion of trans-double bonds and the like, and the macromolecular compatibilizer synthesized by the invention has very obvious compatibilization effect.
Drawings
FIG. 1 shows the principle of preparation of the macromolecular compatibilizer according to the invention. It can be seen from the figure that the macromolecular compatibilizer of the present invention is actually prepared theoretically.
Fig. 2 is an SEM photograph of a blend without adding a compatibilizer and without adding a macromolecular compatibilizer, wherein the cross section of a sample with the macromolecular compatibilizer has rough and irregular surfaces and has gullies, and the cross section of a sample without the compatibilizer is smooth and flat, which indicates that the toughness of the sample becomes better after adding the macromolecular compatibilizer, and more cross-linking points are formed between two phases of the sample during vulcanization, so that the three-dimensional interpenetrating network structure formed is more compact, and the cross-sectional rubbers are pulled against each other during low-temperature brittle fracture, so that the cross section is rougher and has gullies.
FIG. 3 is a DMTA curve of NR/EPDM vulcanizate without compatibilizer and with macromolecular compatibilizer prepared according to the present invention. As can be seen from the figure, the blend without compatibilizer has two damping peaks at-53 deg.C and-37 deg.C, respectively, corresponding to the glass transition temperatures of NR and EPDM, respectively. The blend rubber added with the compatibilizer has only one damping peak at-46.5 ℃, which shows that NR and EPDM have good compatibility and only one glass transition temperature is generated.
Detailed Description
The following examples are specific methods for preparing macromolecular compatibilizers and performance studies applied to the combined use of NR and EPDM. NR used in the preparation was Malaysia STR10 CV. Unless otherwise specified, the percentages listed below are based on mass percent, and the amount of NR added is 100 parts.