Method for predicting performance of FEP terpolymer

Abstract

The invention discloses a method for predicting the performance of an FEP terpolymer. The method comprises the following steps: measuring the weight-average molecular weight or melt flow index of the FEP terpolymer; measuring the content of a third monomer in the FEP terpolymer, wherein the third monomer is fluoroalkyl vinyl ether; on the basis of the measured weight-average molecular weight or the solution flow index and the content of the third monomer, the mechanical property, the dielectric property and the foaming property of the FEP terpolymer material are predicted in combination with a pre-established correlation model. According to the method, the limitation of single characterization dimension in the existing research is broken through, the FEP molecular structure is systematically analyzed by constructing a multi-dimensional characterization method, and the action mechanism of the molecular weight and the third monomer on the FEP terpolymer material is deeply revealed.

Description

Technical Field

[0001] This invention relates to a method for predicting the properties of FEP terpolymers, belonging to the field of FEP terpolymer technology. Background Technology

[0002] Regarding the molecular or aggregated structure of FEP, Wu et al. pioneered the reconstruction of molecular weight distribution models based on melt viscoelastic spectroscopy inversion theory, and Tuminello et al. further established a universal nonlinear mapping relationship between the square root of storage modulus and cumulative molecular weight distribution. However, the dynamic correlation between FEP molecular weight and its third monomer and its rheological behavior remains unresolved. Meanwhile, the understanding of the structure-property relationship between material structural characteristics and macroscopic functional properties (such as dielectric properties, foaming behavior, and rheological behavior) is still extremely limited. Although Chen et al. revealed the main reasons for the poor processing performance of FEP through rheological studies, and Zirkel explored the influence of different processes and nucleating agents on its foaming behavior, these studies all focused on linear analyses of single structural variables and isolated performance responses, failing to construct a structure-property relationship where multiple parameters synergistically affect FEP performance. Summary of the Invention

[0003] The purpose of this invention is to provide a method for predicting the properties of FEP ter copolymers. This method breaks through the limitations of existing research on "single characterization dimension" by constructing a multi-dimensional characterization method to systematically analyze the molecular structure of FEP and deeply reveal the mechanism of action of molecular weight and third monomer on FEP ter copolymer materials.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for predicting the properties of FEP terpolymer materials includes the following steps:

[0006] Determine the weight-average molecular weight or melt flow index of FEP terpolymers.

[0007] The content of the third monomer in the FEP terpolymer was determined; the third monomer was a fluoroalkyl vinyl ether.

[0008] Based on the measured weight-average molecular weight or solution flow index and the content of the third monomer, combined with a pre-established correlation model, the mechanical, dielectric, and foaming properties of FEP terpolymer materials are predicted.

[0009] Preferably, the third monomer is PPVE (perfluoropropyl vinyl ether) or PEVE (perfluoroethyl vinyl ether).

[0010] Preferably, the association model includes:

[0011] When the material processing temperature is below 320℃, the higher the weight-average molecular weight or the lower the melt flow index, the higher the elastic modulus of the material.

[0012] If the weight-average molecular weight is relatively high or the melt flow index is relatively low, the elongation at break and toughness of the material are higher.

[0013] The lower the weight-average molecular weight or the higher the melt flow index, and the less the third monomer is present, the larger the pore size of the foam material made from FEP copolymer.

[0014] Preferably, the correlation model further includes: if the weight-average molecular weight is relatively low or the melt flow index is relatively high, the dielectric loss of the material is lower.

[0015] Preferably, the method for determining the weight-average molecular weight is as follows: first, the complex viscosity data of the FEP terpolymer are fitted using the Carreau-Yasuda model, and then the weight-average molecular weight is calculated according to the following formula:

[0016]

[0017] Where K and α are parameters.

[0018] Preferably, the Carreau-Yasuda model satisfies the following equation:

[0019]

[0020] in, τ represents the absolute value of complex viscosity, a is the time constant, a is the dimensionless parameter describing the transition from the Newtonian plateau to the power-law region, and n is the power-law coefficient.

[0021] Preferably, the method for determining the content of the third monomer is as follows: determining 19 The characteristic peaks associated with the third monomer in the F ss NMR spectrum are analyzed, and the integral area of ​​the characteristic peaks is calculated to determine the content of the third monomer group. The content of the third monomer is then determined based on the content of the third monomer group.

[0022] The beneficial effects of this invention are as follows:

[0023] This invention overcomes the limitations of existing research on "single representation dimension" by constructing a multi-dimensional representation method to systematically analyze...

[0024] The molecular structure of FEP was analyzed, revealing its molecular weight and the mechanism of action of the third monomer. This is the first time that FEP has been studied based on... 19Tests using FSSNMR, IR, XPS, DMA, rheological analysis, and vector network analysis revealed the characteristic behavior of the third monomer in dynamic mechanical properties and melt elasticity, elucidating the physical essence of how the third monomer and molecular weight significantly affect melt elasticity by regulating molecular chain entanglement. Simultaneously, using multidimensional characterization methods, the intrinsic mechanism by which the third monomer and molecular weight influence the dielectric properties of FEP was revealed for the first time, as well as the synergistic effect of the third monomer and molecular weight on the high-temperature foaming behavior of FEP. These findings provide systematic theoretical design principles for developing next-generation FEP foaming materials with ultra-low dielectric loss and high foaming uniformity, which is of great significance for promoting the high-performance application of FEP in 5G / 6G communications and aerospace. Attached Figure Description

[0025] Figure 1 The transmission infrared spectrum of FEPs;

[0026] Figure 2 For (a)FEPs 19 F ss NMR spectrum and (b) locally magnified spectrum in the region of δ = -118 ppm to -27 ppm;

[0027] Figure 3 The C1s spectrum analysis diagram corresponding to the high-resolution X-ray photoelectron spectroscopy (XPS) of FEPs;

[0028] Figure 4 The O1s spectrum corresponding to the high-resolution X-ray photoelectron spectroscopy (XPS) of FEPs;

[0029] Figure 5 The curves show the complex viscosity of FEPs at 300℃. The lines represent the fitted data of the modified Carreau-Yasuda model, and the symbols represent the experimental data.

[0030] Figure 6 The differential molecular weight distribution (DMW) curves of FEPs are shown. The curves are represented by the fitting results of the three-parameter log-normal DMW, and the signs are obtained from the experimental data of G′.

[0031] Figure 7 The DMW curves of the FEPs samples after scaling and normalization;

[0032] Figure 8 DMA curves for FEPs;

[0033] Figure 9 For the frequency scanning curves of different FEPs at different temperatures (280℃, 300℃, 320℃ and 340℃), TTS fitting was performed with 300℃ as the main curve.

[0034] Figure 10(a) Dielectric constant and (b) dielectric loss of FEPs at different frequencies after annealing for 24 hours;

[0035] Figure 11 (a) Dielectric constant and (b) dielectric loss of FEPs at different annealing times at 20.6 GHz;

[0036] Figure 12 The stress-strain curves of FEPs;

[0037] Figure 13 This is a cross-sectional view of FEPs supercritical N2 foamed material;

[0038] Figure 14 This is a statistical chart of the average cell size of FEPs. Detailed Implementation

[0039] Six commercially available FEPs were tested using a melt flow index (MFI) tester and named FEP1, FEP2, FEP3, FEP4, FEP5, and FEP6 according to their MFI (Table 1) from low to high.

[0040] Table 1. Melt flow index of 6 commercially available FEPs

[0041]

[0042] FEP chemical structure analysis

[0043] To determine the relative content of HFP comonomer in FEP, Fourier transform infrared spectroscopy (FTIR) analysis was performed on FEP1-6 samples. Figure 1 Vibrational mode analysis based on the characteristic functional groups of perfluoropolymers shows that the -CF3 group is at 983 cm⁻¹. -1 A significant absorption band is observed at 2386 cm⁻¹. The characteristic absorption peak of the -CF₂- repeating unit is located at 2386 cm⁻¹. -1 Based on the formula The calculated relative mass fractions of hexafluoropropylene (HFP) structural units show (Table 2) that the FEP6 sample had the highest HFP content (13.45%), while the FEP5 sample had the lowest HFP content (11.14%).

[0044] Table 2. Relative HFP content in FEPs

[0045]

[0046] To quantitatively analyze the content of the third monomer in FEP, a solid-state method was used. 19 FEP1-6 was characterized using F ss NMR, and a PFA was selected as a reference. Figure 2As shown in region a, the main peak of the NMR spectrum (δ = -123.6 ppm) belongs to the characteristic fluorine signal (-CF2-) of the tetrafluoroethylene (TFE) structural unit. Furthermore, symmetrically distributed rotating sideband peaks are observed at δ = -230.2 ppm, -17.0 ppm, and δ = -176.9 ppm, -70.5 ppm, respectively. The characteristic peak of -CF3 (-71.7 ppm) is masked by overlap with the rotating sideband peak at -70.5 ppm. Figure 2 The middle b region is Figure 2 The magnified spectrum of region a, from δ = -118 ppm to -27 ppm, shows that PFA and FEP1 / 2 / 4 samples exhibit a significant peak signal at δ ≈ -84 ppm, originating from the -CF3 group of PPVE. Correspondingly, FEP5 / 6 shows a characteristic peak at δ ≈ -90 ppm, originating from the -CF3 group of PEVE. Table 3 shows the content of the corresponding groups calculated from the spectral data. Notably, no characteristic peak of the aforementioned third monomer was detected in FEP3, confirming that this sample did not introduce a third monomer (PPVE or PEVE).

[0047] Table 3. Third monomer group, corresponding chemical shift and content

[0048]

[0049]

[0050] X-ray photoelectron spectroscopy (XPS) analysis of the FEPs samples revealed their surface elemental composition. Full-spectrum scanning showed characteristic photoelectron peaks for C1s, F1s, and O1s in all samples. High-resolution C1s spectral analysis further revealed the presence of these characteristic photoelectron peaks. Figure 3 The spectrum identified four types of carbon species in different chemical states: the main peak at 291.8 ± 0.5 eV, belonging to the main chain -CF2- structure; the secondary peak at 293.5 ± 0.4 eV, corresponding to the branched or terminal -CF3; a weak peak was detected in the 289.7-290.8 eV range, whose binding energy is consistent with the carbonyl (C=O) chemical state; and a C=O peak at 284.8 eV. It is noteworthy that although no C=O groups were present in the sample, they appeared in these spectra. Considering the chemical inertness of FEP materials, the C=O peaks detected in the spectra likely originated from airborne contaminants adsorbed during sample preparation or storage, rather than oxidation products of the material itself. This also corresponds to the subsequent O1s spectral analysis results.

[0051] O 1s fine spectral peak segmentation processing ( Figure 4The results show that the binding energy at 532.2 ± 0.4 eV is attributed to the CO / C=O bond in the adsorbate, while the peak at 535–536 eV belongs to the -O-C3F7 / -O-CF2-CF3 group. This is because the highly electronegative fluorine atom strongly withdraws electrons, leading to a significant increase in the binding energy of the oxygen atom. In contrast, no corresponding characteristic peaks were detected in the 535–536 eV range of the FEP3 sample without the introduction of a third monomer, confirming the results of solid-state NMR characterization.

[0052] Study on the molecular weight and distribution of FEP

[0053] To investigate the influence of FEP's molecular structure on its rheological properties and to further calculate its molecular weight and molecular weight distribution, its rheological behavior was systematically characterized using a Discovery HR-3 rheometer (TA Instruments, USA). The test samples were uniformly compressed into disc-shaped specimens with a thickness of 0.5 mm and a diameter of 25 mm for small amplitude oscillating shear (SAOS) testing. To ensure complete melting of the FEP matrix, experiments were conducted at four temperatures: 280℃, 300℃, 320℃, and 340℃, with nitrogen gas purging as a protective gas throughout the testing process.

[0054] Based on rheological test data, the weight-average molecular weight of FEP was calculated using the following formula. And cumulative molecular weight distribution (I(M)).

[0055] Calculation of weight-average molecular weight

[0056] Calculation of weight-average molecular weight using zero-shear viscosity (η0)

[0057]

[0058] Where K and α are parameters. For FEP, when the molecular weight is above the critical value (1.25 × 10⁻⁶), 4 (g / mol), at 300℃, K=10 -14.5 , α=3.4.

[0059] Cumulative molecular weight distribution calculation

[0060] The cumulative molecular weight distribution (I(M)) was calculated using Turninello's empirical formula:

[0061]

[0062] Among them G' (ωi) It is the dynamic energy storage modulus at angular frequency ω. For platform modulus. It can be calculated using a Maxwell model fitting:

[0063]

[0064] Among them, G' (ω) It is the dynamic energy storage modulus at angular frequency ω, G” (ω) It is the dynamic loss modulus at angular frequency ω; τ is the shear stiffness of the j-th Maxwell element. j It is the relaxation time of the j-th Maxwell unit.

[0065] To convert I(M) from the ω-scale to the molecular weight M-scale, the following function was used:

[0066] τ d =1 / ω=λM 3.4 (6),

[0067] Where τ d It is the longest relaxation time, λ is the scaling factor. On the other hand:

[0068]

[0069] Therefore, λ can be represented as:

[0070]

[0071] Based on the dynamic frequency scan test results Figure 5 The curves showing the functional relationship between complex dynamic viscosity and frequency are presented. The experimentally measured complex viscosity data are fitted using an improved Carreau-Yasuda model (Equation 9).

[0072]

[0073] in The value represents the absolute value of the complex viscosity, τ is the time constant, a is a dimensionless parameter describing the transition from the Newtonian plateau to the power-law region, and n is the power-law coefficient. The fitting results for the complex viscosity are as follows: Figure 5 As shown, the weight-average molecular weight can be calculated according to equation (1), and the relevant results are shown in Table 4. Combining the melt flow index (MFI) data, it was found that the melt flow index and molecular weight show a significant negative correlation; that is, the lower the melt flow index, the higher the weight-average molecular weight of the material. This conclusion is consistent with the basic theory of polymer rheology.

[0074] By combining equations (2)-(8), the relationship curve between the cumulative molecular weight (I(M)) and the molecular weight (M) is obtained. Finally, the derivative of the I(M)-M curve is taken to obtain the differential molecular weight distribution (DMW) curve. In order to accurately characterize the DMW, the experimental data were fitted with a three-parameter log-normal distribution model (as shown in equation (10)).

[0075]

[0076] Where α, β, and Mp are parameters, and W(M) is the weight fraction of molecules with molecular weight M. The experimental data are fitted using equation (10). From the fitting results... Figure 6 As can be seen, the three-parameter log-normal distribution of DMW fits the experimental data well, with a very high degree of agreement. Based on this result, it is used as a reliable characterization of the true molecular weight distribution of FEPs samples. Further, a scaling factor is introduced... With a normalization factor N = 1 / α, the absolute calibration of the DMW curve is achieved. Figure 7 It is worth noting that the multi-dispersion index The calculations exhibit an intrinsic property independent of scaling and normalization processes, thus verifying the intrinsic reliability of rheological analysis of molecular weight distribution. The corresponding parameters for all samples were also obtained. The fitting results are as follows: Figure 7 As shown in Table 5, the parameters corresponding to each sample are as follows. The molecular weight distribution index of the six commercial samples all ranged from 1.4 to 1.6, showing relatively consistent distribution characteristics and small differences between samples.

[0077] Table 4. Zero-shear viscosity (η0), MFI, and weight-average molecular weight of FEPs

[0078]

[0079] Table 5. Molecular weight distribution of FEP

[0080]

[0081]

[0082] The Influence of Third Monomer and Molecular Weight on FEP Performance

[0083] The effect of the third monomer on FEP chain relaxation

[0084] FEP exhibits characteristic peaks near -70℃ and 90℃ in dynamic mechanical analysis (DMA). Figure 8The relaxation of FEP molecules can be attributed to a specific dynamic relaxation process in their molecular chains. Secondary relaxation occurs around -70℃, caused by the movement of linear -CF2- groups. The main peak around 90℃ is the glass transition temperature of the FEP matrix, primarily caused by the movement of FEP chain segments. Except for FEP3, a small peak appears to varying degrees around 127℃, due to secondary movement of local chain segments induced by the branching of the third monomer (PPVE / PEVE), which is activated around 127℃. Meanwhile, FEP3 without the third monomer shows a higher main peak around 90℃ and a lower peak around -70℃, reflecting the lack of locally moving units. Because FEP3 does not contain the third monomer, its molecular chains exhibit higher linear regularity, promoting the formation of locally ordered structures in amorphous regions. These quasi-ordered domains require higher energy to drive cooperative untangling during heating, resulting in greater energy dissipation (tanδ). In FEP with the addition of a third monomer, the high-temperature peak at 90°C and the low-temperature peak at -70°C are very close in height. This is because the branching of the third monomer increases the local motion units, which leads to an increase in the intensity of the low-temperature peak.

[0085] The Influence of Third Monomer and Molecular Weight on the Rheological Behavior of FEP Melt

[0086] The melt rheological behavior of FEP is significantly influenced by its thermal history, primarily due to the kinetic evolution and deentanglement process of residual crystalline phases during processing. For example... Figure 9As shown, the dynamic frequency scan data at 280℃, 320℃, and 340℃ were time-temperature shifted using the time-temperature superposition (TTS) principle, successfully constructing a master curve analysis system for FEPs at a reference temperature of 300℃. To avoid interference from residual crystals on the experimental data, all samples underwent isothermal annealing pretreatment for 10 minutes at the corresponding test temperature. The results show that the storage modulus, loss modulus, and complex viscosity of the FEP3 sample exhibit excellent TTS superposition characteristics across the entire frequency domain, while the other five groups of samples only show good fitting effects in the high-temperature region (≥320℃). In the low-frequency range of 280℃ (<1rad / s), the measured values ​​of the storage modulus of the five groups of samples are significantly larger than the master curve. This anomaly can be explained by introducing a third monomer to enhance the chain entanglement effect: the steric hindrance effect and high rotational freedom of the side chain of the third monomer, and the connection of O atoms to the main chain, increase the flexibility of the molecular chain, enabling it to form a physical entanglement network in the FEP copolymer through van der Waals forces and chain entanglement, significantly enhancing the elastic response of the melt. When the temperature rises above 320℃, thermal motion overcomes the interaction barrier between chain segments, causing the entangled network to completely disintegrate, thus matching the master curve model well. Simultaneously, molecular weight analysis shows that the storage modulus of the FEP samples increases significantly with increasing molecular weight. Measured at 1 rad / s, the values ​​are: FEP1 (7.74 kPa) > FEP2 (4.38 kPa) > FEP3 (2.34 kPa) > FEP4 (2.22 kPa) > FEP5 (0.58 kPa) > FEP6 (0.30 kPa). This trend further verifies the crucial influence of molecular weight on the rheological properties of the material. These phenomena indicate that FEP containing a third monomer, at lower temperatures, exhibits increased melt elasticity due to the entangled network, and the higher the molecular weight, the higher the elastic modulus.

[0087] The Influence of Third Monomer and Molecular Weight on the Dielectric Properties of FEP

[0088] The dielectric properties of the FEPs samples were tested after annealing at 100°C for 24 hours. Figure 10 The data show that FEP3 without the third monomer (PPVE / PEVE) exhibits significantly higher dielectric constant and dielectric loss, while other FEPs containing the third monomer show relatively lower dielectric constant and dielectric loss. This phenomenon is attributed to the synergistic effect of the ether oxygen group and the perfluorinated side chain: the ether oxygen linkage of PPVE and PEVE enhances the flexibility of the molecular chain, and its perfluorinated side chain further improves the mobility of chain segments in the amorphous region. This structural characteristic facilitates more thorough molecular conformation adjustment during melt cooling, effectively alleviating stress concentration during crystalline region growth, reducing the formation of micro-defects, thereby reducing local electric field distortion and consequently lowering the dielectric constant and dielectric loss.

[0089] Comparison of dielectric properties at 100℃ with different annealing times (0h / 1h / 6h / 24h) revealed that ( Figure 11 Annealing has no effect on the dielectric constant, but it exhibits an age-dependent effect on dielectric loss. After annealing at 100℃ for 6 hours, the dielectric loss reaches its lowest threshold. Extending annealing to 24 hours shows no further improvement, indicating that the relaxation of the internal structure of the material tends to reach a steady state within 6 hours. Notably, the high molecular weight sample FEP1 and FEP3 without the third monomer show a more significant reduction in dielectric loss after annealing: the reduction in FEP1 can be attributed to the enhanced chain mobility of the amorphous region by the ether oxygen group in the third monomer, while the reduction in loss in FEP3 is related to the effective repair of processing defects caused by its initial high viscosity during annealing. For the low viscosity FEP5 / FEP6, its optimized melt flow significantly reduces the density of processing-induced microdefects. Combined with the secondary orientation of molecular chains during annealing, this ultimately leads to further optimization of dielectric loss.

[0090] In summary, the lower molecular weight FEP series materials and those containing a third monomer exhibit unique performance advantages: enhanced molecular chain flexibility and amorphous region mobility, combined with optimized processing characteristics, enable them to maintain low-loss dielectric response even at high frequencies (5G millimeter-wave band). These material properties effectively meet the stringent requirements of high-frequency electronic packaging for low dielectric loss and high stability, providing an ideal candidate solution for millimeter-wave communication device packaging.

[0091] The Influence of Third Monomer and Molecular Weight on the Mechanical Properties of FEP

[0092] As shown in the stress-strain curve ( Figure 12 The mechanical properties of the six FEPs were significantly synergistically regulated by the third monomer and molecular weight. FEP3, without the third monomer, exhibited the lowest elongation at break (504%), while the higher molecular weight FEP1 and FEP2, due to increased chain entanglement density, showed elongation at break of 667–686% (Table 6), indicating that increasing molecular weight promotes polymer extensibility. Quantitative analysis of fracture toughness (Table 6) showed that FEP3 without the third monomer had a fracture toughness of only 86 MPa, significantly lower than the low molecular weight systems FEP4 and FEP5 containing the third monomer. Although FEP3 had a higher molecular weight than FEP4 and FEP5, the lack of flexible groups (PPVE / PEVE) introduced by the third monomer resulted in increased chain rigidity and decreased entanglement efficiency, thus limiting energy dissipation. This result clearly verifies the mechanism by which the third monomer improves chain flexibility and entanglement density by altering the molecular chain topology. In summary, molecular weight and the third monomer synergistically regulate the physical entanglement network of the molecular chain, jointly determining the fracture behavior of the material during tensile testing.

[0093] Table 6 Toughness and Elongation at Break of FEP

[0094]

[0095] The Influence of Third Monomer and Molecular Weight on FEP Foaming Behavior

[0096] The process utilizes supercritical nitrogen high-temperature and high-pressure foaming technology (saturation at 280℃ / 20MPa for 90 minutes followed by rapid depressurization in 2 seconds) combined with... Figure 13 SEM characterization revealed that when the molecular weight decreased from 443,000 for FEP1 to 256,000 for FEP5, the average pore size surged from 58 μm to 161 μm. In contrast, the medium-molecular-weight sample FEP3, lacking a third monomer, exhibited significant cell coalescence and rupture due to chain entanglement network defects, resulting in a pore size as high as 237 μm. Rheological analysis showed that the entanglement density advantage of high-molecular-weight FEP1 (its low-frequency storage modulus is an order of magnitude higher than that of FEP5) effectively suppressed cell coalescence. Furthermore, the introduction of the third monomer enhanced the chain entanglement network and molecular flexibility, leading to a significantly smaller pore size in the low-molecular-weight FEP5 sample (76 μm smaller pore size than FEP3) compared to the medium-molecular-weight FEP3 sample without the third monomer. In conclusion, the synergistic strategy of optimizing molecular weight to control melt elastic properties and introducing a third monomer to improve entanglement efficiency is key to overcoming the high-temperature foaming viscoelastic instability bottleneck of FEP resin, providing a multi-scale optimization path for the precise design of high-performance microporous FEP materials.

[0097] In summary, this application has thoroughly investigated the influence mechanism of the third monomer and molecular weight on the performance of FEP through dynamic mechanical analysis (DMA), high-temperature rheological testing, mechanical property testing, and high-frequency dielectric testing, and successfully prepared microporous foamed materials using supercritical nitrogen foaming technology. This application establishes for the first time a multi-scale characterization system for the "structure-property" of FEP materials, elucidating the synergistic regulation mechanism of molecular weight and the third monomer on the material's rheological behavior, dielectric properties, mechanical properties, and foaming behavior. It was found that by controlling the third monomer and molecular weight, the flexibility and entanglement behavior of FEP molecular chains can be effectively optimized, thereby achieving precise control of material properties. The developed multi-scale characterization method can be extended to other fluoropolymer systems, and has important guiding significance for the development of high-performance materials for 5G / 6G high-frequency substrate materials, aerospace, and deep space exploration.

Claims

1. A method for predicting the properties of FEP terpolymer materials, characterized in that, Includes the following steps: Determine the weight-average molecular weight or melt flow index of FEP terpolymers. The content of the third monomer in the FEP terpolymer was determined; the third monomer was a fluoroalkyl vinyl ether. Based on the measured weight-average molecular weight or solution flow index and the content of the third monomer, combined with a pre-established correlation model, the mechanical, dielectric, and foaming properties of FEP terpolymer materials are predicted.

2. The method for predicting the properties of FEP terpolymer materials according to claim 1, characterized in that, The third monomer is PPVE or PEVE.

3. The method for predicting the properties of FEP terpolymer materials according to claim 1, characterized in that, The association model includes: When the material processing temperature is below 320℃, the higher the weight-average molecular weight or the lower the melt flow index, the higher the elastic modulus of the material. If the weight-average molecular weight is relatively high or the melt flow index is relatively low, the elongation at break and toughness of the material are higher. The lower the weight-average molecular weight or the higher the melt flow index, and the less the third monomer is present, the larger the pore size of the foam material made from FEP copolymer.

4. The method for predicting the properties of FEP terpolymer materials according to claim 1, characterized in that, The correlation model also includes: if the weight-average molecular weight is relatively low or the melt flow index is relatively high, the dielectric loss of the material is lower.

5. The method for predicting the properties of FEP terpolymer materials according to claim 1, characterized in that, The method for determining the weight-average molecular weight is as follows: First, the complex viscosity data of the FEP terpolymer are fitted using the Carreau-Yasuda model, and then the weight-average molecular weight is calculated according to the following formula: Where K and α are parameters.

6. The method for predicting the properties of FEP terpolymer materials according to claim 5, characterized in that, The Carreau-Yasuda model satisfies the following equation: in, τ represents the absolute value of complex viscosity, a is the time constant, a is the dimensionless parameter describing the transition from the Newtonian plateau to the power-law region, and n is the power-law coefficient.

7. The method for predicting the properties of FEP terpolymer materials according to claim 1, characterized in that, The method for determining the content of the third monomer is as follows: 19 The characteristic peaks associated with the third monomer in the F ss NMR spectrum are analyzed, and the integral area of ​​the characteristic peaks is calculated to determine the content of the third monomer group. The content of the third monomer is then determined based on the content of the third monomer group.

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