CN107908921B - Method for simulating degradation strength change of heterogeneous phase high polymer - Google Patents

Method for simulating degradation strength change of heterogeneous phase high polymer Download PDF

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CN107908921B
CN107908921B CN201711089422.0A CN201711089422A CN107908921B CN 107908921 B CN107908921 B CN 107908921B CN 201711089422 A CN201711089422 A CN 201711089422A CN 107908921 B CN107908921 B CN 107908921B
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张桃红
金戈愉
曾庆峰
张德政
孙义
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Abstract

The invention provides a method for simulating the degradation strength change of high polymers with different homogeneous phases, which can simulate the change trend of the elastic strength of high polymer materials in the degradation process. The method comprises the following steps: s1, dispersing the high polymer material into cells, and initializing the current reaction time t1(ii) a S2, determining the molecular chain participating in shearing and the time interval delta t of the chain shearing reaction of the molecular chain participating in shearing determined by the distance; s3, at t1At the time of + delta t, the molecular chains participating in shearing generate chain shearing reaction, the states of the cells are updated, different strength calculation formulas are adopted according to the updated states of the cells and aiming at different cell states, and the strength of all the cells is counted to obtain the integral strength of the high polymer material; s4, executing t1＝t1+ Δ t, if t1And if the time is less than the preset diffusion time step, returning to the step S2, otherwise, diffusing the oligomer generated by the chain shearing reaction to the outside of the high polymer material. The invention relates to the field of degradable high polymer materials.

Description

Method for simulating degradation strength change of heterogeneous phase high polymer
Technical Field
The invention relates to the field of degradable high polymer materials, in particular to a method for simulating degradation strength change of high polymers with different phases.
Background
Degradable high molecular polymer (short for polymer) is widely used in human production and life due to its good biocompatibility and degradability, for example, as tissue engineering scaffold, drug controlled release carrier, artificial implant in medical field, etc. The high molecular weight polymer is a compound having a relative molecular weight of ten thousand or more, which is formed by bonding a plurality of atoms or atomic groups mainly by covalent bonds.
In applications of polymeric materials, such as tissue engineering scaffolds, the mechanical properties (especially mechanical strength) of the material are very important, as it must provide some support and attachment for the growth of biological cells and tissues. In the degradation process of the high molecular polymer, the mechanical properties of the high molecular polymer are changed to a certain extent. Therefore, it is an ideal situation to ensure that the scaffold is degraded in time without hindering the growth of cells at the scaffold part, and to ensure that the scaffold has a certain strength within a certain time to play a supporting role, i.e. the strength reduction in the degradation process of the high molecular polymer is consistent with the requirement of increasing tissues or cells. Therefore, the strength change in the degradation process of the biomedical degradable high molecular polymer needs to be researched. The research on the strength change in the polymer degradation process can be divided into a traditional experimental method and a new computer modeling method, and the computer modeling method just makes up for the defects of long period and poor universality of the traditional experimental method.
However, most of the existing computer modeling methods for the degradation process of high polymers simulate the Young modulus, but not the tensile strength.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for simulating the degradation strength change of high polymers with different phases so as to solve the problem that the tensile strength of high polymer materials is not simulated in the prior art.
In order to solve the above technical problem, an embodiment of the present invention provides a method for simulating degradation strength changes of polymers with different homogeneous phases, including:
s1, dispersing the high polymer materialForming a cellular unit and initializing the current reaction time t1；
S2, determining the molecular chain participating in shearing and the time interval delta t of the chain shearing reaction of the molecular chain participating in shearing determined by the distance;
s3, at t1At the time of + delta t, the molecular chain participating in shearing has a chain shearing reaction, the state of the cellular is updated, the strength of each cellular is determined according to the updated state of the cellular, and the strength values of all the cellular are averaged to obtain the integral strength of the high polymer material;
s4, executing t1＝t1+ Δ t, if t1And if the time is less than the preset diffusion time step, returning to the step S2, otherwise, diffusing the oligomer generated by the chain shearing reaction to the outside of the high polymer material.
Further, the S2 includes:
s21, traversing all the cells, and counting the number of molecular chains with each length to obtain the probability of the molecular chains with each length participating in the chain shearing reaction;
s22, according to the probability of the molecular chain with each length participating in the chain shearing reaction, determining the type mu of the molecular chain participating in the shearing and the time interval delta t of the chain shearing reaction from the molecular chain of the type.
Further, the probability α that the molecular chain of the v-th length participates in the chain shearing reactionvExpressed as:
αv＝π×xv
wherein, v is 1,2, M represents the total number of molecular chain species, pi represents the reaction constant, xvIndicates the initial number of molecular chains of the v-th length.
Further, the time interval Δ t of the chain shearing reaction of the molecular chain participating in the shearing, which is determined by the distance, is determined by a first formula, wherein the first formula is expressed as:
Figure GDA0002420797950000021
determining molecular chains participating in the shearing through a second formula, wherein the second formula is expressed as:
Figure GDA0002420797950000022
wherein μ represents the kind of the molecular chain determined to participate in the cleavage, and r1 and r2 represent random numbers.
Further, the conversion rule of the cell state includes:
if the cells are not degraded, the state of the cells is an initial amorphous state;
if the shearing breakage of chains occurs in the cells, the state of the cells is changed from an initial amorphous state to a degraded amorphous state;
if the molecular weight of the cellular is lower than a preset first threshold value, the cellular state is a hole state;
if the number of molecular chains crystallized in the unit cell exceeds a predetermined ratio, the unit cell state is a crystalline state.
Further, the cellular states include: amorphous state, pore state, crystalline state;
wherein, the amorphous state cells are in amorphous phase, the pore state cells are in pore phase, and the crystalline state cells are in crystalline phase;
if the cells exhibit an amorphous phase, the intensity of the cells at time t is:
Figure GDA0002420797950000031
wherein σ (i, j, t) represents the cell [ i ] of the ith row and the jth column][j]Intensity value at time t, σ0Represents a cell [ i ]][j]Initial intensity value of, Mn(i, j, t) represents a cell [ i [ [ i ]][j]Number average molecular weight at time t, M0Representing the initial cell number average molecular mass, α and β being constant, n representing the grid/cell number per column or per row;
if the cell exhibits a pore phase, the intensity of the cell at time t is 0:
if the cell exhibits a crystalline phase, the intensity of the cell at time t is σCWherein σ isCIs a constant determined by the properties of the polymer material itself.
Further, the strength of the high polymer material as a whole is expressed as:
Figure GDA0002420797950000032
wherein the content of the first and second substances,
Figure GDA0002420797950000033
and represents the strength value of the high polymer material at the time t.
Further, the diffusion of the oligomers obeys Fick's second diffusion law, and the macroscopic equation for calculating their diffusion is expressed as:
Figure GDA0002420797950000034
wherein, CeIs the concentration of ester bonds in the polymer, t represents the time, ColIs oligomer concentration, k1For hydrolysis reaction rate constant, k, without catalysis2In order to have the catalytic action condition, the hydrolysis reaction rate constant, D is a diffusion coefficient, grad represents a gradient, and div represents a divergence.
Further, the diffusion coefficient D is expressed as:
D＝D0+(1.32-0.33)(D1-D0)
wherein D is0Diffusion coefficient of oligomer in polymer, D1The diffusion coefficient of the oligomer in the pores is the porosity;
the porosity is expressed as:
Figure GDA0002420797950000041
among them, CellsholeCell, the total number of Cells in the state of a poresumIs the total number of cells.
Further, the S1 includes: initializing the total reaction time t2；
After S4, the method further includes:
s5, after the oligomer is diffused outwards, the total reaction time t is updated2＝t2+ Preset diffusion time step, will t1Reset to the initial value, return to S2 to perform the next round of chain shearing reaction of the molecular chain until t2And if the total reaction time is larger than the preset total reaction time threshold value, stopping iteration.
The technical scheme of the invention has the following beneficial effects:
in the above scheme, the high polymer material is dispersed into cells, and the current reaction time t is initialized1(ii) a Determining the time interval delta t of the chain shearing reaction of the molecular chain participating in shearing and the molecular chain participating in shearing determined by the distance; at t1At the time of + delta t, the molecular chains participating in shearing have chain shearing reaction, the state of the cellular is updated after the chain shearing reaction, the strength of each cellular is determined according to the updated state of the cellular, and the strength values of all the cellular are averaged to obtain the integral strength of the high polymer material; performing t1＝t1+ Δ t, if t1And if the time is less than the preset diffusion time step, returning to the step S2, otherwise, diffusing the oligomer generated by the chain shearing reaction to the outside of the high polymer material. Therefore, simulation of the degradation process from micro-molecular chain shear fracture to macro-diffusion modeling can be realized, the variation trend of the strength of the high polymer material in the degradation process is obtained through simulation, and a numerical basis is provided for the optimized design of the precise medical clinical equipment of the high polymer degradable polymer in the aspect of mechanical property.
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FIG. 1 is a schematic flow chart of a method for simulating degradation strength variation of high polymers with different phases according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating a detailed method for simulating degradation strength variation of polymers with different phases according to an embodiment of the present invention;
FIG. 3 is a schematic view of chain shear fracture of a polymer provided in accordance with an embodiment of the present invention;
FIG. 4 is a graph showing the comparison between the simulation result of the number average molecular weight of a polymer material sample as a function of degradation time and experimental data provided by an embodiment of the present invention;
FIG. 5 is a graph showing the results of a simulation of the crystallinity of a sample of polymeric material as a function of degradation time and experimental data comparing the results provided by an example of the present invention;
fig. 6 is a comparison between simulation results and experimental data of strength of polymer material samples as a function of degradation time according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a method for simulating degradation strength change of high polymers with different phases, aiming at solving the problem that the tensile strength of the high polymer materials is not simulated at present.
As shown in fig. 1, a method for simulating degradation strength variation of a heterogeneous high polymer provided by an embodiment of the present invention includes:
s1, dispersing the high polymer material into cells, and initializing the current reaction time t1；
S2, determining the molecular chain participating in shearing and the time interval delta t of the chain shearing reaction of the molecular chain participating in shearing determined by the distance;
s3, at t1At the time of + delta t, the molecular chain participating in shearing has a chain shearing reaction, the state of the cellular is updated, the strength of each cellular is determined according to the updated state of the cellular, and the strength values of all the cellular are averaged to obtain the integral strength of the high polymer material;
s4, executing t1＝t1+ Δ t, if t1And if the time is less than the preset diffusion time step, returning to the step S2, otherwise, diffusing the oligomer generated by the chain shearing reaction to the outside of the high polymer material.
The method for simulating degradation strength change of high polymers with different phases, provided by the embodiment of the invention, is used for dispersing high polymer materials into cells and initializing current reaction time t1(ii) a Determination of molecular chains and distances involved in cleavageDetermining the time interval delta t of the chain shearing reaction of the molecular chain participating in shearing; at t1At the time of + delta t, the molecular chains participating in shearing have chain shearing reaction, the state of the cellular is updated after the chain shearing reaction, the strength of each cellular is determined according to the updated state of the cellular, and the strength values of all the cellular are averaged to obtain the integral strength of the high polymer material; performing t1＝t1+ Δ t, if t1And if the time is less than the preset diffusion time step, returning to the step S2, otherwise, diffusing the oligomer generated by the chain shearing reaction to the outside of the high polymer material. Therefore, simulation of the degradation process from micro-molecular chain shear fracture to macro-diffusion modeling can be realized, the variation trend of the strength of the high polymer material in the degradation process is obtained through simulation, and a numerical basis is provided for the optimized design of the precise medical clinical equipment of the high polymer degradable polymer in the aspect of mechanical property.
In this embodiment, in order to simulate the degradation strength variation of the heterogeneous high polymer, the high polymer material is first dispersed into a large number (n × n) of mesoscopic cellular lattices according to the size of the high polymer material, and the current reaction time t is initialized1Initializing the total reaction time t2. During initialization, each unit cell has a molecular chain with normally distributed molecular weight (the average molecular weight is the initial molecular weight of the material). Each cell needs to initialize its state according to the properties of the polymer material itself. Cell [ i ] of memory cell][j]( i 1, 2.. times.n; j 1, 2.. times.n) state is cell [ i [][j]State, the four states that a cell may appear during degradation can be represented by numbers:
Figure GDA0002420797950000061
the conversion rule of the cellular state is as follows:
if the cells are not degraded (i.e., the molecular chains in the cells do not undergo a chain shearing reaction), the state of the cells is still 1;
once the molecular chain is cut off in the cells, the state of the cells is changed from 1 to 0;
as the degradation is further carried out, if the molecular weight of the cellular is lower than a preset first threshold (the first threshold is specifically determined by the properties of the high polymer material), the cellular is considered to generate pores and is changed into a porous state, and the state is-1;
if the number of molecular chains crystallized in the unit cell exceeds a preset ratio (the value of the ratio is specifically determined by the properties of the high polymer material), the unit cell is considered to be in a crystalline state, and the state is-2.
In this embodiment, for the cellular obtained by dispersing the high polymer material, a monte carlo algorithm may be adopted to randomly select the molecular chain participating in the shearing, and determine the time interval Δ t between the determined molecular chain participating in the shearing and performing the chain shearing reaction (S2), specifically:
a11, traversing all the cells, counting the number of molecular chains of each length, and assuming that there are M molecular chains of different lengths, the initial number of molecular chains of each length is x1，x2，……，xMSetting the reaction constant π, by αv＝π×xvProbability α of molecular chain of v-th length participating in chain shear reactionvWherein, v ═ 1, 2.., N;
a12, randomly generating two random numbers r1 and r2 with unit intervals evenly distributed, and calculating Δ t and μ according to the formulas (1) and (2):
Figure GDA0002420797950000071
Figure GDA0002420797950000072
wherein the unit interval is a real number interval of [0,1),. DELTA.t represents a time interval at which the molecular chain participating in the cleavage is subjected to the chain cleavage reaction, and. mu.m represents a kind of the molecular chain participating in the cleavage.
At t1At time + Δ t, a chain scission reaction of the μmolecular chain is performed, which generates crystals with a certain probability, p represents the crystallization probability, RsIndicating all chain breaks, the crystallinity XcCan pass through Xc＝pRsAnd (4) calculating.
After the chain shearing reaction, updating the state of the cells, and counting the physical attributes of the cells, wherein the physical attributes comprise: number of chains, molecular weight.
Then, calculating the mechanical strength of each unit cell, wherein the polymer material has the coexistence of crystalline state, amorphous state and pore state at the same time, wherein the amorphous state unit cell is represented as amorphous phase, the pore state unit cell is represented as pore phase, and the crystalline state unit cell is represented as crystalline phase;
the calculation methods of the intensities of the three phase cells are different, specifically:
b11, since the intensity change of the amorphous phase (i.e., amorphous unit cell) is most affected by the molecular weight, if the unit cell appears as the amorphous phase, the intensity of the unit cell at time t can be expressed as:
Figure GDA0002420797950000073
wherein σ (i, j, t) represents the cell [ i ] of the ith row and the jth column][j]Intensity value at time t, σ0Represents a cell [ i ]][j]Initial intensity value of, Mn(i, j, t) represents a cell [ i [ [ i ]][j]Number average molecular weight at time t, M0Representing the initial cell number average molecular mass, α and β being constant (determined specifically by the polymer material properties), n representing the number of cells per column or row of cells;
b12, the strength is considered to be 0 because the pore phase (pore state cells) loses the supporting effect and the mechanical properties collapse when the molecular weight is lower than a certain threshold;
b13, the strength of the crystalline phase (crystalline cells) is σ since the crystals can increase the strength of the copolymer, and the strength of the crystalline phase cells is larger than that of the amorphous phaseCWherein σ isCIs a constant determined by the properties of the polymer material itself.
In conclusion, a model (also called a different phase strength model) of the degradation strength change of the high polymer is obtained, and the model is expressed as follows:
Figure GDA0002420797950000081
the intensity of the cellular cells (i, j) at the time t can be calculated through the high polymer degradation intensity change model.
In this embodiment, the average value of the intensity values of all the cells is obtained, so as to obtain an average value of the intensity of the polymer material changing along with the degradation time, where the average value of the intensity may represent the intensity of the whole polymer material:
Figure GDA0002420797950000082
wherein the content of the first and second substances,
Figure GDA0002420797950000083
and represents the strength value of the high polymer material at the time t.
In this embodiment, t is executed1＝t1+ Δ t, increase the current reaction time by Δ t if t1Less than a predetermined diffusion time step Δ t2Then, the Monte Carlo algorithm is calculated again, the next shearing chain breaking reaction is executed, and the process is circulated until the current reaction time is more than or equal to the preset diffusion time step length delta t2The oligomers produced by the chain shearing reaction diffuse out of the polymeric material.
In this example, the diffusion of the oligomer follows Fick's second diffusion law, and the macroscopic equation for calculating its diffusion is expressed as:
Figure GDA0002420797950000084
wherein, CeIs a high polymer ester bond concentration, ColIs oligomer concentration, k1For hydrolysis reaction rate constant, k, without catalysis2In order to have the catalytic action condition, the hydrolysis reaction rate constant, D is a diffusion coefficient, grad represents a gradient, and div represents a divergence.
In this embodiment, the diffusion coefficient D is expressed as:
D＝D0+(1.32-0.33)(D1-D0)
wherein D is0Diffusion coefficient of oligomer in polymer, D1The diffusion coefficient of the oligomer in the pores is the porosity;
the porosity is expressed as:
Figure GDA0002420797950000091
among them, CellsholeTotal number of Cells in the state of-1 (pore state), CellssumIs the total number of cells.
In this example, the total reaction time t is updated after the diffusion of the oligomers out2＝t2+ a preset diffusion time step, resetting the current reaction time to 0, returning to S2 for the next round of chain shearing reaction of the molecular chain until t2And if the total reaction time is larger than the preset total reaction time threshold value, stopping iteration.
In summary, in the method for simulating degradation strength changes of polymers with different phases in this embodiment, a polymer material is discretized in a cellular manner, and based on the cells obtained by discretization, molecular chains participating in shearing in microscopic view are randomly selected on different cells through a monte carlo algorithm; after the molecular chains participating in shearing are broken, recrystallization is carried out with a certain probability, and meanwhile, oligomers generated by chain shearing reaction diffuse to the outside of the high polymer material; the above reactions cause the change of properties such as the molecular weight and the number of chains of the cells, and also cause the transition of the state of the cells; the method comprises the steps of establishing a high polymer degradation strength change model based on a series of evolutions of cells, wherein the high polymer degradation strength change model is used for predicting the strength of each cell at a certain moment according to the number average molecular weight of the cell at the certain moment and the state of the cell at the moment, and finally counting the strength of the whole high polymer material at the moment, so that the simulation of a degradation process is realized from the shearing fracture of a molecular chain under the micro condition to the diffusion modeling under the macro condition, the change trend of the strength of the high polymer material in the degradation process is simulated, and a numerical basis is provided for the optimization design of the precision medical clinical equipment of the high polymer degradable polymer in the aspect of mechanical property. The embodiment is suitable for different application fields of degradable high polymer equipment.
In order to better understand the method for simulating the degradation strength change of the heterogeneous phase high polymer in this embodiment, a mixed high polymer material of polylactic acid (PLLA, 60%) and polyvinyl alcohol (PVA, 40%) is taken as an example, and the method for simulating the degradation strength change of the heterogeneous phase high polymer proposed in this embodiment is described in detail:
in this embodiment, the parameters are set as: n is 700, initial crystallinity Xc0Initial molecular weight M ═ 00＝9.26×104g/mol, the preset total reaction time threshold is T-3.1104 × 107s (12 months), other parameters are shown in Table 1,. DELTA.t2Representing a preset diffusion time step.
TABLE 1 parameters of intensity calculation model
D0 D1 π k1 k2 α β Δt2
1.0×10-9 1.2×10-5 0.002 0.042 0.002 1.23 1.1 700
The method for simulating degradation strength change of the high polymer with different homogeneous phases provided by the embodiment specifically comprises the following steps:
(1) as shown in FIG. 2, the high polymer material is discretized into n × n equal parts of cells (mesoscopic sized cells), the cells are initialized, and the two-dimensional array Cell [ is ] is used][]Storage, Cell (a, b) is marked as Cell [ a ]][b]Let us assume the current reaction time t1Total reaction time t ═ 02＝0。
(2) The cell state cell [ i ] [ j ] _ state is set, and in this example, since the high polymer material is initially amorphous, all the cell initial states are amorphous, i.e., "1" states.
Neighbor cells may employ the von Neumann 4 neighbor model.
(3) Traversing all the cells, counting the number of the molecular chains of each length, specifically, as shown in fig. 3, using a one-dimensional array, ChainNumber [ ] to store the number of the molecular chains of each length.
(4) As shown in fig. 2, the kind μ of the molecular chain participating in the shearing and the time interval Δ t of the chain shearing reaction from the molecular chain of the kind are randomly determined according to the monte carlo algorithm.
(5) At t1At time + Δ t, a chain scission reaction is performed, and the broken molecular chain produces two new chains.
(6) After the chain shearing reaction, updating the state of the cells, and counting the physical attributes of the cells, wherein the physical attributes comprise: number of chains N (i, j), molecular weight Mn (i, j).
(7) And respectively calculating the strength of the cells according to the states and molecular weights of different cells, and averaging the strength values of all the cells to obtain the integral strength of the high polymer material.
(8) Update time t1＝t1+Δt1，t1<Δt2Time (Δ t)2: a preset diffusion time step), returning to the step (3), otherwise, executing the step (9).
(9) The diffusion of the oligomers is performed using a macroscopic diffusion equation calculation.
(10) Outputting a calculation result, and re-counting and recording the physical attributes of the cells;
(11) after diffusion of the oligomers outwards, the total reaction time t is renewed2＝t2+Δt2Will t1Resetting to 0, returning to the step (3) to carry out the chain shearing reaction of the molecular chain of the next round until t2And stopping iteration when the total reaction time is larger than a preset total reaction time threshold value T.
In this embodiment, the comparison schematic diagrams of the simulation result of the number average molecular weight, the crystallinity and the strength of the polymer material sample changing with the degradation time and the experimental data are respectively shown in fig. 4, fig. 5 and fig. 6, and the correctness of the method for simulating the degradation strength change of the polymer with different homogeneous phases described in this embodiment is verified by the comparison results described in fig. 4, fig. 5 and fig. 6.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (9)

1. A method for simulating degradation strength change of heterogeneous phase high polymers, which comprises the following steps:
s1, dispersing the high polymer material into cells, and initializing the current reaction time t1；
S2, determining the molecular chain participating in shearing and the time interval delta t of the chain shearing reaction of the molecular chain participating in shearing determined by the distance;
s3, at t1At the time of + delta t, the molecular chain participating in shearing has a chain shearing reaction, the state of the cellular is updated, the strength of each cellular is determined according to the updated state of the cellular, and the strength values of all the cellular are averaged to obtain the integral strength of the high polymer material;
s4, executing t1＝t1+ Δ t, if t1If the diffusion time step length is less than the preset diffusion time step length, returning to execute S2, otherwise, diffusing the oligomer generated by the chain shearing reaction to the outside of the high polymer material;
wherein the cellular states include: amorphous state, pore state, crystalline state;
wherein, the amorphous state cells are in amorphous phase, the pore state cells are in pore phase, and the crystalline state cells are in crystalline phase;
if the cells exhibit an amorphous phase, the intensity of the cells at time t is:
Figure FDA0002420797940000011
wherein σ (i, j, t) represents the cell [ i ] of the ith row and the jth column][j]Intensity value at time t, σ0Represents a cell [ i ]][j]Initial intensity value of, Mn(i, j, t) represents a cell [ i [ [ i ]][j]Number average molecular weight at time t, M0Representing the initial cell number average molecular mass, α and β being constant, n representing the grid/cell number per column or per row;
if the cellular phase is represented by a pore phase, the strength of the cellular phase at the time t is 0;
if the cell exhibits a crystalline phase, the intensity of the cell at time t is σCWherein σ isCIs a constant determined by the properties of the polymer material itself.
2. The method for simulating degradation strength variation of heterogeneous high polymer according to claim 1, wherein the step S2 comprises:
s21, traversing all the cells, and counting the number of molecular chains with each length to obtain the probability of the molecular chains with each length participating in the chain shearing reaction;
s22, according to the probability of the molecular chain with each length participating in the chain shearing reaction, determining the type mu of the molecular chain participating in the shearing and the time interval delta t of the chain shearing reaction from the molecular chain of the type.
3. The method for simulating degradation strength variation of heterogeneous high polymer according to claim 2, wherein the probability α that the molecular chain with the v-th length participates in the chain shearing reactionvExpressed as:
αv＝π×xv
wherein, v is 1,2, M represents the total number of molecular chain species, pi represents the reaction constant, xvIndicates the initial number of molecular chains of the v-th length.
4. The method for simulating degradation strength variation of heterogeneous high polymer according to claim 3, wherein the time interval Δ t of chain shearing reaction of the molecular chains participating in shearing is determined by a first formula, wherein the first formula is represented as:
Figure FDA0002420797940000021
determining molecular chains participating in the shearing through a second formula, wherein the second formula is expressed as:
Figure FDA0002420797940000022
wherein μ represents the kind of the molecular chain determined to participate in the cleavage, and r1 and r2 represent random numbers.
5. The method for simulating degradation strength variation of heterogeneous high polymers according to claim 1, wherein the transformation rule of cellular states comprises:
if the cells are not degraded, the state of the cells is an initial amorphous state;
if the shearing breakage of chains occurs in the cells, the state of the cells is changed from an initial amorphous state to a degraded amorphous state;
if the molecular weight of the cellular is lower than a preset first threshold value, the cellular state is a hole state;
if the number of molecular chains crystallized in the unit cell exceeds a predetermined ratio, the unit cell state is a crystalline state.
6. The method for simulating degradation strength variation of heterogeneous high polymer according to claim 1, wherein the strength of the whole high polymer material is expressed as:
Figure FDA0002420797940000023
wherein the content of the first and second substances,
Figure FDA0002420797940000024
and represents the elastic strength value of the high polymer material at the moment t.
7. The method for simulating degradation strength change of heterogeneous high polymer according to claim 1, wherein the diffusion of the oligomer follows Fick's second diffusion law, and the macroscopic equation for calculating the diffusion is expressed as:
Figure FDA0002420797940000031
wherein, CeIs the concentration of ester bonds in the polymer, t represents the time, ColIs oligomer concentration, k1For hydrolysis reaction rate constant, k, without catalysis2In order to have a catalytic action, the rate constant of the hydrolysis reaction is DDiffusion coefficient, grad gradient, div divergence.
8. The method for simulating degradation strength variation of heterogeneous high polymer according to claim 7, wherein the diffusion coefficient D is expressed as:
D＝D0+(1.32-0.33)(D1-D0)
wherein D is0Diffusion coefficient of oligomer in polymer, D1The diffusion coefficient of the oligomer in the pores is the porosity;
the porosity is expressed as:
Figure FDA0002420797940000032
among them, CellsholeCell, the total number of Cells in the state of a poresumIs the total number of cells.
9. The method for simulating degradation strength variation of heterogeneous high polymer according to claim 1, wherein the step S1 comprises: initializing the total reaction time t2；
After S4, the method further includes:
s5, after the oligomer is diffused outwards, the total reaction time t is updated2＝t2+ Preset diffusion time step, will t1Reset to the initial value, return to S2 to perform the next round of chain shearing reaction of the molecular chain until t2And if the total reaction time is larger than the preset total reaction time threshold value, stopping iteration.
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