CN114031806A - Preparation method of sericite-doped expandable polystyrene composite beads - Google Patents

Preparation method of sericite-doped expandable polystyrene composite beads Download PDF

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CN114031806A
CN114031806A CN202111097829.4A CN202111097829A CN114031806A CN 114031806 A CN114031806 A CN 114031806A CN 202111097829 A CN202111097829 A CN 202111097829A CN 114031806 A CN114031806 A CN 114031806A
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sericite
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李俊锋
赵志峰
王鑫磊
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Jilin University
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    • C08J9/16—Making expandable particles
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    • C08F112/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
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    • C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
    • C08J2325/02—Homopolymers or copolymers of hydrocarbons
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    • C08J2433/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2433/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
    • C08J2433/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
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    • C08J2455/02—Acrylonitrile-Butadiene-Styrene [ABS] polymers
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Abstract

The invention relates to a preparation method of doped sericite expandable polystyrene composite beads, which comprises the steps of carrying out in-situ polymerization on a styrene monomer by a viscosity increasing method, namely adding a certain amount of polystyrene, ABS resin or polymethyl methacrylate into the styrene monomer, adding a dispersant solution after increasing the viscosity of a styrene phase, and carrying out suspension polymerization to obtain the doped sericite polystyrene beads. The method for preparing the sericite-doped expandable polystyrene composite beads by the advanced viscosity increasing method has stable process, avoids the phenomenon of kettle sticking, can utilize polystyrene waste products in the preparation, and can realize diversified and multifunctional preparation of the polystyrene beads.

Description

Preparation method of sericite-doped expandable polystyrene composite beads
Technical Field
The invention belongs to the technical field of energy-saving new materials, and particularly relates to a preparation method of sericite-doped expandable polystyrene composite beads.
Background
Studies have found that sericite doped (expandable) polystyrene can improve the mechanical and thermal properties of polystyrene bead products. The preparation and performance research of waste polystyrene-based composite materials discloses sericite/polystyrene composite materials prepared by a suspension distillation method, wherein the mechanical properties, the thermal properties and the like of the sericite/polystyrene composite materials are improved.
Chinese patent CN110218397A discloses a method for preparing ultra-low thermal conductivity sericite/expandable polystyrene beads, which comprises doping modified sericite in styrene monomer before suspension polymerization, adding foaming agent into the obtained polystyrene beads through one-step method or two-step method, and preparing sericite/expandable polystyrene beads. Because the thermal conductivity coefficient (0.419-0.670W/(m.K)) and specific heat value (0.87J/(kg.K)) of the sericite are lower than those of graphite, the prepared sericite/expandable polystyrene foam product has a lower thermal conductivity than that of the graphite/expandable polystyrene foam product. Chinese patent CN101289519A also discloses a preparation method of the organic-inorganic composite foamable material, and discloses the composite advantages of vinyl monomers and mica.
Although the sericite doped polystyrene improves various performances of the material, the method for synthesizing the doped sericite doped polystyrene composite bead is not satisfactory, the existing method for preparing the doped sericite doped polystyrene composite bead has high kettle adhesion probability, and the phenomenon of adhesion is easy to occur during suspension polymerization, so that the improvement is urgently needed.
Disclosure of Invention
The invention provides a stable and feasible preparation method for directly preparing doped sericite polystyrene composite beads by using a styrene monomer and sericite as basic raw materials, wherein a part of the styrene monomer is converted into polystyrene by a method of increasing the viscosity in the early stage, or PS, PMMA or ABS with a certain proportion is added into the styrene monomer, so that the viscosity of a composite system is increased, the sedimentation centrifugal movement rate of the sericite in a suspension phase is reduced, and the problem of adhesion during later stage suspension polymerization is solved.
The purpose of the invention is realized by the following technical scheme:
a preparation method of doped sericite expandable polystyrene composite beads takes a styrene monomer and sericite as raw materials, and prepares the doped sericite expandable polystyrene composite beads in a mode of increasing viscosity in advance, which comprises the following steps:
A. sequentially adding sericite, a styrene monomer, an initiator and other auxiliary agents into a reaction kettle, stirring at normal temperature to dissolve the initiator, a nucleating agent and a flame retardant and uniformly dispersing the sericite in the styrene monomer to obtain a composite system;
B. the viscosity of the composite system is improved by a mode of increasing the viscosity in advance, when the viscosity reaches 35-8000 cP, a dispersant solution is added, heated and stirred, and suspension polymerization is carried out until the doped sericite polystyrene beads are obtained;
C. and D, adding a foaming agent into the sericite polystyrene composite beads prepared in the step B through a one-step method or a two-step method to obtain the doped sericite expandable polystyrene beads.
Further, the initiator is benzoyl peroxide or benzoyl peroxide and tert-butyl peroxybenzoate with the mass ratio of 1-5: 1, and the mass ratio of the styrene monomer to the initiator is 100: 0.1-2, wherein the sericite is modified oleophylic sericite, the mass ratio of the styrene to the polystyrene to the mass ratio of the styrene to the sericite is 100: 1-10, wherein the mass ratio of the dispersing agent solution is 100: 0.01-3: 0.01-0.3: 0.5-4 of desalted water, a surfactant, a water-soluble polymer and soluble salt, wherein the volume ratio of a dispersant solution to a styrene monomer solution is (1-3): 1.
further, the surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium oleate or sodium stearate, the water-soluble polymer is at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, methyl hydroxypropyl cellulose, polyvinyl alcohol and gelatin, and the soluble salt is sodium sulfate or potassium sulfate.
Further, the other auxiliary agents include nucleating agents, crosslinking agents and flame retardants.
Further, in the step B, the viscosity is increased in advance by a composite system in-situ polymerization mode, a high-molecular dissolution mode or an alternation of the two modes.
Further, the in-situ polymerization mode of the composite system comprises the following specific steps: stirring the styrene monomer in a reaction kettle at 80-120 ℃ for in-situ polymerization before suspension polymerization of the styrene monomer, continuously converting the styrene monomer in the reaction kettle into polystyrene, and continuously increasing the viscosity of a composite system along with the pre-polymerization.
Further, in the step B, the specific steps of the polymer dissolution method are: at room temperature, at least one of Polystyrene (PS), ABS resin (ABS) or polymethyl methacrylate (PMMA) which are easily dissolved in styrene monomer high molecular compounds is added into the composite system, and the viscosity of the composite system is increased along with the dissolution of the added high molecular compounds.
And step C, in the one-step foaming agent adding method, the beads are taken out of the reaction kettle in suspension polymerization for observation, when the beads are precipitated in water and hardened at 90 ℃, the foaming agent is added, the temperature is increased for continuous reaction for 3-9 hours, and the doped sericite developable polystyrene composite beads are obtained through cooling, separation, drying, screening, film coating and the like.
And step C, performing two-step foaming agent adding method, namely performing suspension polymerization to obtain beads with residual monomers of less than or equal to 0.5%, cooling, separating, drying and screening, and adding the screened beads into a foaming agent to obtain the sericite-doped developable polystyrene composite beads.
Compared with the prior art, the invention has the beneficial effects that: the viscosity of the composite system is improved, so that the subsequent suspension polymerization can be effectively prevented from adhesion, and the composite system has the following advantages:
1. the advanced viscosity increasing method of the invention not only can make the preparation process of sericite doped polystyrene suspension polymerization beads more stable, but also can prepare other inorganic non-metallic material doped polystyrene beads by properly adjusting the viscosity of a composite system, thereby realizing the diversification and the multifunctionality of the doping of the polystyrene beads, and providing a stable synthesis method for developing new products of the polystyrene beads;
2. according to the polymer dissolution method, by dissolving PMMA, ABS and other high molecular compounds which are easily dissolved in styrene monomers, the smooth preparation of PS/PMMA beads, PS/ABS beads, sericite/PS/PMMA beads and sericite/PS/ABS beads can be realized, and the smooth preparation of PS/other beads can be realized;
3. the polymer dissolution method of the invention can dissolve polystyrene to improve the viscosity of the composite system before suspension polymerization, and can utilize polystyrene waste beads and waste polystyrene products to change waste into valuable.
4. The implementation and popularization of the method have good social benefit and economic benefit.
Drawings
FIG. 1 is an optical photograph of sericite expandable polystyrene composite beads;
FIG. 2 is an electron micrograph of the surface morphology of sericite expandable polystyrene composite beads;
FIG. 3 is an optical photograph of sericite expandable polystyrene composite beads after foaming;
FIG. 4 is an optical photograph of a foam board;
FIG. 5 is an electron micrograph of cells;
FIG. 6 is an XRD plot of sericite (a), polystyrene beads (b) and sericite polystyrene composite beads (c);
FIG. 7 is FTIR curves for sericite (a), polystyrene beads (b) and sericite polystyrene composite beads (c);
FIG. 8 shows Thermogravimetric (TGA) curves of sericite polystyrene composite beads doped with 0% (a), 3% (b) and 6% (c).
Fig. 9 shows Thermogravimetric (TGA) curves of ABS sericite composite beads (a), polystyrene beads (b), and PMMA sericite composite beads (c).
Detailed Description
The invention relates to a preparation method of sericite-doped expandable polystyrene composite beads, which comprises the steps of increasing the viscosity of a styrene monomer phase by a method of increasing the viscosity in advance before suspension polymerization, and then adding a dispersing agent for suspension polymerization to obtain the sericite-doped expandable polystyrene composite beads. The examples are only a part of the present application, and not all examples, and the expandable polystyrene resin prepared based on the premise belongs to the protection scope of the present invention.
It is found through experiments that the inorganic non-metallic material such as sericite has high density, such as the density of sericite (2.7-3.5 g/cm)3) Greater than the density of graphite (2.09-2.33 g/cm)3) Much higher than the density of styrene (0.909 g/cm)3). The reason that the doping in the styrene affects the stability of the suspension polymerization is as follows: in the suspension polymerization system, sericite is dispersed in a styrene phase and forms a spherical dispersed phase together with styrene, and is suspended and dispersed in an aqueous phase. The styrene density and viscosity in the spherical dispersed phase at the initial stage of suspension polymerization are low (for example, the styrene density at 60 ℃ C. is 0.887 g/mL)-1And the viscosity is 0.45cP), the spherical disperse phase in the water phase rotates and revolves under the action of gravity and stirring, the resultant force of the centrifugal force and the gravity borne by the sericite particles is far greater than that of a styrene monomer with the same volume, and the sericite particles move to the phase interface of the spherical disperse phase under the action of the resultant force until the phase interface is broken and separated, so that the instability of a suspension system is caused, and the problems of kettle adhesion and the like are caused.
The viscosity of the composite system is increased by the Stokes formula, according to which the sedimentation rate of the substances in the spherical disperse phase, V0＝(ρ1-ρ2)g′d2[ 18 ] mu, where ρ 1 is a sericite density, ρ 2 is a styrene (polystyrene-containing) density, g' is a combined acceleration due to a resultant force of gravity, a rotation centrifugal force and a revolution centrifugal force, d is a sericite equivalent particle diameter, and μ is a composite system viscosity, and V is a value obtained by adding a polystyrene-containing resin to the composite system0Can be regarded as the equivalent sedimentation rate of the sericite in the composite force field. In the formula, d and ρ 1 are constants, ρ 2 is regarded as a constant as a slight increase in polymerization of styrene or dissolution of a polymer, and g' is a total acceleration due to the resultant force, and is regarded as a constant during stable stirring. ByThis is known as V0Inversely proportional to the viscosity mu. The essence of the in-situ polymerization or polymer dissolution method is that the content of high molecules in the spherical dispersed phase is increased, the viscosity mu of the system is increased, and the movement rate V of the sericite is increased0The reduction of the content of the sericite is beneficial to keeping the sericite in a stable dispersion state in a spherical dispersion phase, and a suspension polymerization system tends to be stable.
In order to avoid the problems and improve the stability of the preparation of the sericite doped polystyrene beads, the invention utilizes a method of increasing viscosity in advance and combines a dispersant solution with special dispersion effect to carry out suspension polymerization, thereby effectively solving the problems and providing a stable process method for the preparation of the polystyrene beads by doping high-density materials such as sericite and the like.
The preparation method of the sericite-doped expandable polystyrene composite bead comprises the following steps:
adding sericite, a styrene monomer, an initiator and other additives in a certain weight proportion into a reaction kettle, stirring to dissolve the initiator and other additives and uniformly disperse the sericite in the styrene monomer, and continuously stirring to increase the viscosity of the styrene monomer by the following method.
Specifically, the other auxiliary agents include nucleating agents and flame retardants.
The initiator is benzoyl peroxide or benzoyl peroxide and tert-butyl peroxybenzoate in a mass ratio of 1-5: 1.
The mass ratio of the styrene monomer to the initiator is 100: 0.1 to 2.
The sericite is modified oleophylic sericite, and the surface of the sericite is oleophylic by adding a surface modifier, such as silane, titanate and the like.
The mass ratio of the styrene to the polystyrene to the sericite is 100: 1 to 10. Preferably, the mass ratio of the heat preservation solution used for heat preservation is 100: 5 to 6.
The dispersant solution is prepared by mixing the following components in a mass ratio of 100: 0.01-3: 0.01-0.3: 0.5-4 of desalted water, a surfactant, a water-soluble polymer and soluble salt, wherein the volume ratio of a dispersant solution to a styrene monomer is (1-3): 1. wherein the surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium oleate or sodium stearate, the water-soluble polymer is at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, methyl hydroxypropyl cellulose, polyvinyl alcohol and gelatin, and the soluble salt is sodium sulfate or potassium sulfate.
The foaming agent can be pentane, butane, isopentane and the like, and the addition amount of the foaming agent is 2-15% of the mass of the beads.
The method for realizing the advanced viscosity increasing method comprises the following steps:
1. in-situ polymerization of a composite system: before suspension polymerization, a styrene composite system containing auxiliaries such as sericite and an initiator in a reaction kettle is stirred and heated for in-situ polymerization, so that the in-situ polymerization viscosity of a styrene monomer is increased. The method specifically comprises the following steps: heating and stirring, continuously converting styrene monomers in the reaction kettle into polystyrene, continuously increasing the viscosity of the system along with the prepolymerization, adding a dispersant solution to continue stirring when the viscosity of the bulk prepolymerization system reaches 35-8000 cP, uniformly dispersing the organic phase into the dispersant solution, and continuously heating, stirring and carrying out suspension polymerization.
2. Polymer dissolution method: at room temperature, one to three of high polymers PS, PMMA or ABS are added into a styrene phase in any combination, the combination proportion is not limited, the viscosity of the high polymers added into a composite system is continuously increased along with the dissolution of the PS, ABS or PMMA, and when the viscosity of the composite system reaches 35-8000 cP, a dispersant solution can be added for subsequent suspension polymerization.
3. The in-situ polymerization method and the high-molecular dissolution method of the composite system can be alternated, when the in-situ polymerization and the high-molecular dissolution method are alternately carried out, the in-situ prepolymerization time and the PS, ABS and PMMA dissolution amount are not limited, and only the viscosity index of the composite system is controlled. When the viscosity of the system reaches 35-8000 cP, a dispersant solution can be added for subsequent suspension polymerization.
When the three methods of the prior viscosity increasing method are used, the viscosity of the composite system is measured, and when the styrene monomer phase viscosity reaches 35-8000 cP, a dispersant solution can be added for subsequent suspension polymerization.
The obtained sericite polystyrene composite beads can be added with a foaming agent through a one-step method or a two-step method to further obtain sericite expandable polystyrene composite beads.
The method for adding the foaming agent in the one-step method is that the beads are taken out from a reaction kettle in suspension polymerization for observation, when the beads sink in water and are hardened at 90 ℃, the foaming agent is added, the temperature is increased, and the reaction is continued for 3-9 hours, and specifically comprises the following steps: keeping the temperature for 40min, heating to 115 ℃ at the heating rate of 0.1-1 ℃/min, and carrying out constant temperature polymerization for 150min at 115 ℃. And then cooling, separating, drying, screening, coating and the like to obtain the doped sericite developable polystyrene composite beads.
The two-step foaming agent adding method is that the beads with residual monomers less than or equal to 0.5 percent obtained by suspension polymerization are cooled, separated, dried and screened, and the obtained beads are added with the foaming agent to obtain the sericite-doped developable polystyrene composite beads.
Example 1
10g Na was added to 500ml of desalted water2SO40.15 sodium dodecyl sulfate and 0.25 sodium carboxymethyl cellulose are dissolved at 40 ℃ to obtain the dispersing agent.
10g of sericite, 180g (200mL) of styrene, 1.5g of benzoyl peroxide, 3g of hexabromocyclododecane, 0.37g of tert-butyl peroxybenzoate, 0.35g of DCP and 0.38g of nucleating agent are weighed into a 1L autoclave, stirred at the normal temperature and the normal pressure at 500rpm, heated to 83 ℃ gradually, in-situ polymerization is started and the viscosity of a styrene phase is measured, and the viscosity of the styrene phase is measured at 100min to be 48 cP.
Keeping the rotating speed at 500rpm, adding 380mL of the dispersing agent, stabilizing for 30min, heating to 85 ℃, keeping the temperature for 140min, checking whether the particles sink and harden in water at normal temperature, adding 1g of calcium hydroxy phosphate powder if the particles sink and harden, and sealing the kettle. The rotation speed was maintained at 500rpm, and the temperature was raised to 115 ℃ at a rate of 0.2 ℃/min. Adding 14g of pentane and N by using a pressure balance feeding device2Keeping the pressure at 0.80Mpa for 40 min; then heating to 117 ℃ at the heating rate of 0.6 ℃/min, keeping the temperature for 240min, then cooling to room temperature by cold water, discharging, drying and screening. Obtaining sericite composite expandable polystyreneThe appearance and surface morphology of the beads are shown in FIGS. 1-2, the expanded beads, foam boards and cells are shown in FIGS. 3-5, and XRD and FTIR curves are shown in FIGS. 6 and 7.
Example 2
9.9kg of modified sericite, 135kg of styrene, 1kg of benzoyl peroxide, 3kg of hexabromocyclododecane, 370g of tert-butyl peroxybenzoate, 350g of DCP and 380g of nucleating agent are weighed in a 900L autoclave, stirred at 140rpm under normal pressure, added with 45kg of polystyrene waste and stirred until the polystyrene waste is completely dissolved, and the viscosity of a styrene phase is 218 cP.
Maintaining the rotation speed at 140rpm, adding dispersant 390L (containing 0.8% sodium oleate, 0.01% hydroxymethyl cellulose, 1% Na) at 40 deg.C2SO4And 0.015% gelatin) and stabilized for 30min, heated to 85 ℃ and kept at the constant temperature for 140min, and checked whether the particles sink and become hard in water at normal temperature, and if so, 1kg of calcium hydroxy phosphate powder is added and the kettle is sealed. The rotation speed was maintained at 140rpm, and the temperature was raised to 115 ℃ at a rate of 0.2 ℃/min. Adding 16kg of pentane and N by using a pressure balance feeding device2Keeping the pressure at 0.78Mpa for 40 min; then heating to 117 ℃ at the heating rate of 0.6 ℃/min, keeping the temperature for 240min, then cooling to room temperature by cold water, discharging, drying and screening. The sericite composite expandable polystyrene beads are obtained, and can be packaged and sealed after film coating and screening.
Example 3
Sericite/polystyrene composite beads with 1 to 8% of sericite doping amount respectively were prepared according to example 1 or example 2, and 25% of polystyrene waste material could be used in the synthesis of conventional expandable polystyrene beads to utilize the polystyrene waste material when example 2 was applied. The thermogravimetric curves of the polystyrene composite beads with the doped sericite contents of 0%, 3% and 6% are shown in FIG. 8. The thermal conductivity of the polystyrene composite foam board with the doped sericite content of 1-8% is shown in table 1.
TABLE 1
Figure BDA0003269573980000071
Example 4
Weighing PMMA 10kg, styrene 50kg, sericite 2.5kg and BPO 0.5kg, putting into 250L reaction kettle, stirring at 150rpm, heating to 88 deg.C, maintaining the temperature for 2.5h, adding dispersant solution (containing 0.8% sodium oleate, 0.01% polyvinyl alcohol and 1% Na)2SO4And 0.015% gelatin), setting and maintaining the temperature in the kettle at 78 ℃ for 1.2h, then heating and maintaining the temperature in the kettle to 80 ℃ for 3.5h, after the particles in the reaction kettle sink in the desalted water, continuously heating to 93 ℃ at the heating rate of 6 min/DEG C, and maintaining for 6 h. Finally, cooling the system to below 40 ℃ and discharging. And separating, washing, drying and screening the product to obtain the polystyrene/PMMA composite beads containing sericite.
Example 5
5kg of ABS and 50kg of styrene were weighed, and the weighed materials were put into a 250L reaction kettle, stirred, and completely dissolved at 40 ℃. Adding sericite 2.5kg and BPO 0.5kg into a reaction kettle, stirring at 150rpm, setting the temperature in the kettle at 83 deg.C, stirring at constant temperature, and adding dispersant solution (containing 0.8% sodium oleate, 0.01% polyvinyl alcohol, and 1% Na) into the reaction kettle when the viscosity of the system reaches 1200cP2SO4And 0.015% of gelatin), setting the temperature in the reaction kettle to be 79 ℃ and keeping the temperature for 1.5h, raising the temperature in the reaction kettle to 81 ℃ and keeping the temperature for 4h, and raising the temperature to 86 ℃ at the temperature rise rate of 5 min/DEG C and keeping the temperature for 6.5h after the particles in the reaction kettle sink in water. Finally, cooling the system to below 40 ℃ and discharging. And separating, washing, drying and screening the product to obtain the polystyrene/ABS composite bead containing sericite.
The thermogravimetric curves of the sericite polystyrene composite beads obtained in example 3, example 5 and example 6 are shown in FIG. 9.
As can be seen from the optical photograph of fig. 1, the composite beads have uniform particle size and a slightly sericite color, and as can be seen from the electron micrograph of fig. 2, the composite beads have a spherical structure and smooth surfaces, and as can be seen from the surface electron micrograph (c), sericite is uniformly distributed on the surfaces of the composite beads.
As can be seen from fig. 6 to 8, the cell arrangement of the composite beads is compact and uniform, and the cell structure is a closed cell structure with a substantially circular or polygonal shape. Sericite is uniformly dispersed in the interior or on the surface of polystyrene cells, thereby effectively reducing internal heat transfer and reducing energy loss.
In fig. 6, a, b and c are XRD curves of sericite, polystyrene beads and sericite polystyrene composite beads, respectively. Diffraction peaks near 8.89 °, 17.8 °, 20.1 °, 26.8 °, 45.6 °, and 50.1 ° in the figure correspond to sericite, with the diffraction peak at 26.8 ° being the sharpest. The drum peaks around 10 ° and 20 ° are contributed by the polystyrene body. The doped sericite polystyrene composite beads have obvious diffraction peaks at 26.8 degrees, which are consistent with the strong diffraction peaks of sericite, and the wider diffraction peaks are caused by the high integrity of the sericite crystal structure and the tight arrangement of the internal particles. For the doped sericite polystyrene composite beads, the weak peak also indicates that sericite has entered the polystyrene matrix and its structure is not destroyed.
In FIG. 7, FTIR curves for sericite, polystyrene beads and sericite polystyrene composite beads, a, b and c, respectively. In the figure, 3628cm-1The absorption peak at (A) is an Al-OH vibration absorption peak of sericite. 1024cm-1The peak at (A) is the antisymmetric tensile vibration absorption peak of Si-O-Si. 840cm-1The absorption peak at (a) corresponds to the symmetrical tensile vibration absorption peak of Si-O-Si. 757cm-1The absorption peak of (A) is a tensile vibration absorption peak of Al-O-Si. 696cm-1The absorption peak at (A) is the stretching vibration absorption peak of Si-O. 531cm-1The absorption peak of (2) is a bending vibration absorption peak of Si-O. 3060-3030cm-1The peak value of the region is a C-H bond stretching vibration absorption peak on a benzene ring. Peak area 2000--1Is a bending vibration absorption peak of a C-H bond of a benzene ring. From the above analysis, it was concluded that sericite was dispersed between polystyrene main chains by physical adsorption since no new characteristic peak was generated.
In fig. 8, a, b and c are Thermogravimetric (TGA) curves of the polystyrene composite beads doped with 0%, 3% and 6% sericite, respectively. As can be seen from fig. 5, the temperatures corresponding to the weight loss of 5% for the 0%, 3%, and 6% sericite polystyrene composite beads were 349 ℃, 354 ℃, and 360 ℃. The doping of the sericite improves the thermal stability of the polystyrene skeleton, namely, part of the polystyrene main chain is connected with the sericite interface, so that the decomposition rate of the main chain is effectively reduced. Constant weight after 465 ℃, and the infrared characterization residue is sericite which is consistent with the proportion of added sericite.
In fig. 9, a, b and c are Thermogravimetric (TGA) curves of ABS sericite composite beads, polystyrene beads and PMMA sericite composite beads, respectively. As can be seen from fig. 6, the mass fractions of the ABS sericite polystyrene composite beads, the polystyrene beads, and the PMMA sericite polystyrene composite beads at 408 ℃ are 58.58%, 49.8%, and 46.45%, respectively. It is shown that the addition of ABS improves the thermal stability of the composite beads. Constant weight after 465 ℃, and the infrared characterization residue is sericite which is consistent with the proportion of added sericite.

Claims (9)

1. A preparation method of sericite-doped expandable polystyrene composite beads is characterized by comprising the following steps: the method is characterized in that a styrene monomer and sericite are used as raw materials, and the doped sericite polystyrene composite beads are prepared in a mode of increasing viscosity in advance, and comprises the following steps:
A. sequentially adding sericite, a styrene monomer, an initiator and other auxiliary agents into a reaction kettle, stirring at normal temperature to dissolve the initiator, a nucleating agent and a flame retardant and uniformly dispersing the sericite in the styrene monomer to obtain a composite system;
B. the viscosity of the composite system is improved by a mode of increasing the viscosity in advance, when the viscosity reaches 35-8000 cP, a dispersant solution is added, heated and stirred, and suspension polymerization is carried out until the doped sericite polystyrene beads are obtained;
C. and D, adding a foaming agent into the sericite polystyrene composite beads prepared in the step B through a one-step method or a two-step method to obtain the doped sericite expandable polystyrene beads.
2. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 1, wherein: the initiator is benzoyl peroxide or benzoyl peroxide and tert-butyl peroxybenzoate with the mass ratio of 1-5: 1, and the mass ratio of the styrene monomer to the initiator is 100: 0.1-2, wherein the sericite is modified oleophylic sericite, the mass ratio of the styrene to the polystyrene to the mass ratio of the styrene to the sericite is 100: 1-10, wherein the mass ratio of the dispersing agent solution is 100: 0.01-3: 0.01-0.3: 0.5-4 of desalted water, a surfactant, a water-soluble polymer and soluble salt, wherein the volume ratio of a dispersant solution to a styrene monomer solution is (1-3): 1.
3. the method for preparing sericite-doped expandable polystyrene composite beads according to claim 1, wherein: the surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium oleate or sodium stearate, the water-soluble polymer is at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, methyl hydroxypropyl cellulose, polyvinyl alcohol and gelatin, and the soluble salt is sodium sulfate or potassium sulfate.
4. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 1, wherein: the other auxiliary agents include nucleating agents, crosslinking agents and flame retardants.
5. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 1, wherein: and step B, the viscosity is increased in advance by adopting a composite system in-situ polymerization mode, a high-molecular dissolution mode or two alternative modes.
6. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 5, wherein: the in-situ polymerization mode of the composite system comprises the following specific steps: stirring the styrene monomer in a reaction kettle at 80-120 ℃ for in-situ polymerization before suspension polymerization of the styrene monomer, continuously converting the styrene monomer in the reaction kettle into polystyrene, and continuously increasing the viscosity of a composite system along with the pre-polymerization.
7. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 5, wherein: the specific steps of the polymer dissolving mode in the step B are as follows: at room temperature, at least one of Polystyrene (PS), ABS resin (ABS) or polymethyl methacrylate (PMMA) which are easily dissolved in styrene monomer high molecular compounds is added into the composite system, and the viscosity of the composite system is increased along with the dissolution of the added high molecular compounds.
8. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 1, wherein: and step C, taking the beads out of the reaction kettle in suspension polymerization for observation, adding the foaming agent when the beads sink in water and are hardened at 90 ℃, raising the temperature for continuously reacting for 3-9 h, cooling, separating, drying, screening, coating and the like to obtain the sericite-doped developable polystyrene composite beads.
9. The method for preparing sericite-doped expandable polystyrene composite beads according to claim 1, wherein: and step C, the method for adding the foaming agent in the two-step method is to obtain beads with residual monomers less than or equal to 0.5% through suspension polymerization, then cool, separate, dry and screen the beads, and add the screened beads into the foaming agent to obtain the sericite-doped developable polystyrene composite beads.
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