Method and apparatus for evaluating outgassing of non-metallic materials

Abstract

The application discloses a method and device for evaluating the outgassing property of nonmetallic materials, and the method comprises the following steps: placing a sample in a vacuum cavity, vacuumizing the vacuum cavity, heating the sample according to a preset program, keeping the temperature constant after heating, recording the change of the pressure in the vacuum cavity with time in the heating process stage and / or the constant temperature stage to obtain a characteristic pressure-time curve, extracting at least one characteristic parameter for evaluating the outgassing property from the characteristic pressure-time curve, and evaluating the outgassing property of the sample according to the characteristic parameter. The application can quickly, low-cost and defect-relatedly evaluate the outgassing property of nonmetallic materials.

Description

Technical Field

[0001] This invention relates to the field of component testing and analysis technology, and in particular to a method and apparatus for evaluating the gas release properties of non-metallic materials. Background Technology

[0002] In applications with extremely stringent internal environmental stability requirements, such as hermetically sealed electronic device packaging, spacecraft cabin components, and high-vacuum scientific instruments, the outgassing characteristics of components and their non-metallic packaging materials (including but not limited to adhesives, potting compounds, plastic housings, and cable insulation layers) under vacuum or sealed environments are considered one of the core critical parameters affecting the long-term reliability and service life of the system. Outgassing refers to the process by which gas molecules (such as water vapor, oxygen, nitrogen, carbon monoxide, or residual organic solvents) adsorbed inside or on the surface of non-metallic materials are released into the surrounding sealed space when subjected to thermal excitation or pressure changes during manufacturing, storage, or use. This process not only leads to the deterioration of the vacuum level within the packaging cavity but may also trigger a series of secondary failure mechanisms such as electrochemical corrosion, contact contamination, and optical component fogging.

[0003] To assess and control the risks arising from material gas release, several standardized testing methods have been developed in the existing technological system, such as ASTM E595 (for testing total mass loss (TML) and collected volatile condensate (CVCM)) and the Chinese aerospace industry standard QJ1558A. The core evaluation logic of these standard methods is usually based on statistically analyzing the total mass change of the material before and after the thermal vacuum test, or calculating the average gas release rate per unit time. However, research has revealed the following unresolved technical shortcomings in these existing technologies: First, there is a lack of dynamic time-series information. Existing methods only provide "total" or "average" indicators of gas release behavior, completely ignoring the details of the gas release process's evolution over time. In fact, gas release is a typical dynamic physicochemical process, and its rate, onset time, duration, and fluctuation patterns all contain crucial information about the gas source and release mechanism. Traditional methods cannot distinguish whether the gas originates from rapid physical desorption from the material surface or from slow diffusion through complex pathways within the material's bulk phase—the latter often being directly related to the material's intrinsic structure (such as crosslinking density and free volume distribution) and processing defects, and is a key criterion for evaluating the material's intrinsic quality.

[0004] Second, it is impossible to correlate specific physical mechanisms. Due to the lack of detailed analysis of the pressure-time curve morphology, existing technologies cannot attribute observed gas release events to specific physical processes (e.g., surface adsorbate layer volatilization, bulk diffusion-controlled release, or sudden rupture of internal microcracks / bubbles). This deficiency makes it difficult for engineers to trace the source of unacceptable gas release behavior to specific process steps or material defect types, thus severely limiting the efficiency of material selection, process improvement, and failure analysis.

[0005] Third, testing is costly and time-consuming. While some existing technologies can perform online analysis of released gas components using expensive equipment such as quadrupole mass spectrometers (QMS), such equipment is not only extremely expensive to purchase and maintain, but the testing cycle usually takes several days to several weeks, making it difficult to meet the needs of rapid sampling inspection on production lines or screening of incoming materials from suppliers.

[0006] In summary, there is an urgent need in this field to develop a rapid, low-cost method and supporting device for evaluating the gas release behavior of non-metallic materials that can correlate gas release behavior with specific physical defect mechanisms. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method and apparatus for evaluating the gas release properties of non-metallic materials in a fast, low-cost manner and in relation to specific physical mechanism defects.

[0008] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide a method for evaluating the gas release properties of non-metallic materials, comprising the following steps: Perform a thermal vacuum test: Place the standard sample into a vacuum chamber, evacuate the vacuum chamber, heat the standard sample according to a preset program and keep it at a constant temperature after heating. Record the pressure change in the vacuum chamber over time during the heating process and / or the constant temperature stage to obtain the characteristic pressure-time curve. Data analysis: Extract at least one characteristic parameter for evaluating gas release from the characteristic pressure-time curve, and evaluate the gas release of the standard sample based on the characteristic parameter.

[0009] Furthermore, prior to the step of conducting the thermal vacuum test, the following steps are also included: Obtaining the background pressure: Under no-load conditions, the vacuum chamber is evacuated and a stable background pressure value is obtained; Prior to the data analysis step, the following steps are also included: The characteristic pressure-time curve is filtered and smoothed, and the background pressure value is subtracted.

[0010] Furthermore, prior to the step of conducting the thermal vacuum test, the following steps are also included: Sample pretreatment: The non-metallic material sample to be tested is cleaned, dried and cut into a uniform shape and surface area to obtain a standard sample.

[0011] Furthermore, the feature parameters include temporal feature parameters and / or morphological feature parameters; The time-domain characteristic parameters include: the time of appearance of the pressure value peak relative to the isothermal starting point and the duration of pressure fluctuations inside the vacuum device. The morphological characteristic parameters include: the peak value of the pressure wave, the slope of the curve, and the height of the pressure plateau after the curve tends to stabilize in the later stage of isothermal operation.

[0012] Furthermore, the data analysis steps include: The gas release properties of non-metallic materials are evaluated based on the peak value of the pressure wave; the lower the peak value, the better the gas release properties. The gas release properties of non-metallic materials are evaluated based on the slope of the curve; the gentler the slope, the better the gas release properties. The gas release properties of non-metallic materials are evaluated based on the slope of the curve and the height of the pressure plateau. The smaller the slope and the lower the height of the pressure plateau, the better the gas release properties of the non-metallic material. The pressure platform height represents the total amount of gas that can be released from the standard sample at the evaluation temperature.

[0013] Furthermore, the data analysis step further includes: analyzing the pressure peaks appearing in the characteristic pressure-time curve based on the time-domain characteristic parameters and morphological characteristic parameters, thereby determining the gas release mode of the standard sample and associating it with the specific physical mechanism; wherein the gas release mode includes at least: The first mode is defined as a peak that appears earlier than the first threshold, has a symmetrical shape, and a half-width at half-maximum (WHM) less than or equal to the second threshold. This mode corresponds to the rapid desorption of gases adsorbed on or near the surface of the material. The second mode is defined as a wave peak that appears later than the third threshold, has an asymmetrical shape with a slow rise and a fast fall, and has a half-width at half-maximum greater than or equal to the fourth threshold. This mode corresponds to a gas release process controlled by bulk diffusion of the material. The third mode is defined as a peak occurrence time that is random, a peak amplitude that exceeds the fifth standard deviation of the baseline noise, and a rise time that is less than or equal to the fifth threshold. This mode corresponds to the instantaneous rupture of internal defects in the material or the burst of highly volatile impurity particles.

[0014] Furthermore, it also includes a comprehensive evaluation step: if the proportion of the second mode in the gas release mode of the standard sample is greater than a predetermined proportion, and the number of events belonging to the third mode is less than a predetermined number, then the non-metallic material corresponding to the standard sample is evaluated as high quality, uniform and stable.

[0015] Furthermore, the preset procedure includes: heating the standard sample to a preset evaluation temperature at a preset constant heating rate, and maintaining the temperature at the evaluation temperature for a predetermined duration.

[0016] Furthermore, the evaluation temperature is at least one. When there are two or more evaluation temperatures, the thermal stability of the material is evaluated by comparing the characteristic pressure-time curves of the same material at different evaluation temperatures.

[0017] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is: to provide a device for evaluating the gas release properties of non-metallic materials, comprising: A vacuum chamber, configured to contain standard samples to be evaluated; The test module is configured to evacuate the vacuum chamber, heat the standard sample according to a preset program and keep it at a constant temperature, and record the pressure change in the vacuum chamber over time during the heating process and / or the isothermal stage after heating, thereby generating a characteristic pressure-time curve. A data analysis module is configured to extract at least one characteristic parameter for evaluating gas release from the characteristic pressure-time curve, and to rapidly evaluate the gas release of the standard sample based on the characteristic parameter.

[0018] The method and apparatus for evaluating the gas release properties of non-metallic materials of the present invention have at least the following beneficial effects: (i) By analyzing the temporal and morphological characteristics of the characteristic pressure-time curve, this invention can for the first time link the observed gas release behavior to a specific physical mechanism, distinguish the source of gas release, and provide a direct and in-depth scientific basis for material process optimization, defect tracing and failure analysis, overcoming the shortcomings of traditional total quantity indicators that only know what happens but not why.

[0019] (ii) This invention only requires conventional thermal vacuum equipment (without the need for expensive gas composition analysis instruments such as quadrupole mass spectrometers), which greatly reduces equipment investment and evaluation costs, making the method easy to popularize and apply in production lines, materials research and development departments and quality inspection laboratories.

[0020] (III) By monitoring the pressure changes caused by the release of gas from materials in a confined space, this invention can sensitively distinguish the differences in gas release from different materials, providing a quantitative basis for quality comparison in material selection and process optimization.

[0021] (iv) Compared with traditional quality loss testing that takes several days or even weeks, the entire testing and data analysis process of this invention can be completed in a few hours, which greatly improves the evaluation efficiency and is suitable for rapid sampling on the production line or preliminary screening of material suppliers.

[0022] (v) By testing the same material at different evaluation temperatures and comparing its characteristic curves, this invention can provide additional information about the thermal stability of the material and the trend of the release activation energy, which is something that existing single-temperature point total quantity testing methods cannot achieve. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of one embodiment of the method for evaluating the gas release properties of non-metallic materials according to the present invention.

[0024] Figure 2 This is a flowchart of another embodiment of the method for evaluating the gas release properties of non-metallic materials according to the present invention.

[0025] Figure 3 This is a structural block diagram of one embodiment of the apparatus for evaluating the gas release properties of non-metallic materials according to the present invention. Detailed Implementation The following disclosure provides various embodiments or examples for implementing different features of the present invention. Specific examples will be described below to simplify the invention. Of course, these are merely examples and are not intended to limit the invention.

[0026] Although the numerical ranges and parameter settings presented in this invention are approximations, the numerical settings in specific instances are reported as precisely as possible. Any numerical value inherently contains some necessary error arising from the standard deviation found in the respective test measurements. Similarly, as used herein, the term "about" generally refers to within 10%, 5%, 1%, or 0.5% of a given value or range. Alternatively, the term "about" means within an acceptable average standard error that can be conceived by one of ordinary skill in the art. Except in instances of operation / work, or unless expressly stated otherwise, all numerical ranges, totals, values, and percentages, such as those for material quantities, durations, temperatures, operating conditions, amounts, and other similarities disclosed herein, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameter settings set forth in this invention and the appended claims are approximations that can be changed upon request. At a minimum, each numerical parameter should be interpreted based on the number of significant figures reported and the application of ordinary rounding techniques. A range herein may be expressed as from one endpoint to another or between two endpoints. All scopes disclosed herein include endpoints unless otherwise stated.

[0027] Furthermore, the technical parts described in this invention and the appended claims are primarily the improved technical parts of this invention, and do not limit the object protected by this invention to only having these technical parts. Other known essential components (structures and / or methods) and / or non-essential components of the object protected, besides the technical parts described in this invention and the appended claims, are not included in this invention and the appended claims because they do not fall within the scope of improvements of this invention; however, this does not mean that the object protected by this invention does not possess these known components.

[0028] Please see Figure 1 This is a flowchart of one embodiment of the method for evaluating the gas release properties of non-metallic materials according to the present invention. This embodiment includes the following steps: S100. Sample Pretreatment. The non-metallic material sample to be tested is cleaned, dried, and cut into a uniform shape and surface area to obtain a standard sample.

[0029] Reference Figure 1 The flowchart depicts a method for evaluating the gas release properties of non-metallic materials, in an exemplary embodiment of the invention, beginning with a sample pretreatment step S100. In this step, one or more samples are obtained from the non-metallic material to be tested (e.g., but not limited to epoxy adhesive sheets, polytetrafluoroethylene heat shrink tubing, silicone rubber sealing rings, or polyimide films). The samples are subjected to cleaning, drying, and geometric normalization to obtain standard samples with a consistent initial state. This pretreatment step ensures that all standard samples to be tested have a uniform shape and surface area, reducing errors introduced by differences in sample state.

[0030] In one specific, but non-limiting, example, the cleaning process is performed by immersing the sample in an organic solvent (preferably anhydrous ethanol or isopropanol) and applying ultrasonic vibration for approximately 15 to 30 minutes, thereby removing processing debris, oil, or other soluble contaminants adhering to the sample surface. Subsequently, the sample is removed from the organic solvent and the surface is purged with high-purity nitrogen gas (purity ≥99.999%) to remove any remaining solvent. The drying process is performed by placing the cleaned sample in a vacuum drying oven and maintaining it at a temperature range of 50°C to 60°C and an absolute pressure below 100 Pa for approximately 2 to 4 hours, thereby substantially removing ambient moisture absorbed inside and on the surface of the sample. To ensure the repeatability and comparability of test results, the geometric standardization process requires cutting or shaping the sample into a geometry with a predetermined shape (e.g., a circular sheet, a square sheet, or a tube segment of a specified length) and a predetermined exposed surface area (e.g., for sheet-like standard samples, the diameter is set to 10 mm ± 0.1 mm and the thickness is set to 1 mm ± 0.05 mm).

[0031] In an alternative embodiment, for small, uncut finished parts (such as miniature O-rings), the standardization process is carried out by using a fixed number (e.g., 10) of the same model parts as a set of standard samples. After the above pretreatment, the standard samples are immediately transferred to a sealed container filled with a dry, inert gas (e.g., nitrogen or argon) and cooled to room temperature (approximately 23°C ± 2°C) to prevent re-hygroscopicity during the waiting period for testing.

[0032] S200. Obtain the background pressure. Under no-load conditions, evacuate the vacuum chamber and obtain a stable background pressure value.

[0033] To ensure that the equipment itself is free from leakage or venting interference, in a preferred embodiment, after the sample pretreatment step S100, the method further includes a background acquisition step S200. The purpose of this step is to characterize the residual pressure and drift characteristics of the thermal vacuum equipment itself in the absence of sample contribution, thereby providing a baseline reference for subsequent signal correction.

[0034] In one exemplary implementation of this step, the thermal vacuum chamber (vacuum cavity) of the thermal vacuum apparatus is closed and sealed with no sample placed inside (i.e., "empty state"). A vacuum pump system in fluid communication with the thermal vacuum chamber (preferably comprising an oil-free scroll dry pump as a backing pump and a turbomolecular pump as a high-vacuum stage pump) is activated to begin evacuating the internal volume of the thermal vacuum chamber. During evacuation, a high-precision pressure sensor coupled to the thermal vacuum chamber (e.g., a capacitive thin-film gauge with a range of 0.1 Pa to 100 kPa and an accuracy of 0.2% of the reading) is used to continuously monitor the internal pressure. When the absolute pressure inside the thermal vacuum chamber is reduced below a predetermined threshold (e.g., 5.0 × 10⁻⁶ kPa), the pressure is evacuated. - After reaching 3 Pa, continue evacuation and monitor pressure changes. Once the pressure fluctuation does not exceed ±1% of the predetermined threshold (e.g., for 5.0 × 10⁶ Pa) within a time window of at least 30 minutes, [further details are needed]. - The threshold for ³ Pa should not fluctuate by more than ±5.0 × 10⁻⁶ Pa. -5 If the pressure exceeds a certain threshold (Pa), the system is considered to have reached a stable background state. Subsequently, the arithmetic mean of the pressure sensor outputs over a future period (e.g., 10 to 30 minutes) is recorded; this average is defined as the background pressure value. In an alternative embodiment, to account for potential temperature drift or slow venting, the background pressure value is recorded as a slowly varying background curve over time, rather than a single constant.

[0035] In this embodiment, the thermal vacuum equipment is a standard thermal vacuum equipment without gas analysis function. It is a conventional thermal vacuum equipment and does not require complex analytical instruments such as quadrupole mass spectrometers, which greatly reduces costs.

[0036] S300. Conduct a thermal vacuum test. Place the standard sample into the vacuum chamber, evacuate the chamber, heat the standard sample according to a preset program, and maintain a constant temperature after heating. Record the pressure change in the vacuum equipment over time during the heating process and / or the constant temperature stage to obtain a characteristic pressure-time curve.

[0037] After completing sample pretreatment (S100) and optional background acquisition (S200), the method according to the invention proceeds to the thermal vacuum test step S300. In this step, the pretreated standard sample is placed in a thermal vacuum chamber (vacuum cavity) of a thermal vacuum device (e.g., the same or similar device used in step S200) and subjected to a temperature-pressure process simulating a thermal vacuum environment.

[0038] In one detailed implementation, firstly, the standard sample is removed from the sealed container and placed on a sample holder inside the heated vacuum chamber. The sample holder is designed with a material having low heat capacity and low outgassing rate (e.g., polished and cleaned stainless steel or aluminum) to minimize interference from the holder itself on the outgassing measurement. Subsequently, the heated vacuum chamber is closed and sealed, and the vacuum pump system is activated to evacuate the chamber. When the pressure inside the chamber drops again below the stable pressure reached in the background acquisition step (e.g., below 5.0 × 10⁻⁶), the pressure is evacuated. - When the temperature reaches 3 Pa, the heating program is initiated. The heating program is executed by an electric heating element embedded in the wall of the hot vacuum chamber or the sample holder, and is controlled in a closed loop by a programmable logic controller (PLC) or a proportional-integral-derivative (PID) temperature controller.

[0039] In a preferred embodiment, the heating procedure is configured to first heat the standard sample from an initial temperature (typically room temperature, approximately 23°C) to a preset evaluation temperature at a predetermined constant heating rate (e.g., but not limited to, about 5°C / min, 10°C / min, or 15°C / min). The evaluation temperature is selected depending on the intended application of the material under test. For example, for non-metallic materials used in aerospace applications, the evaluation temperature is typically set to 75°C, 100°C, or 125°C; for general electronic packaging materials, the evaluation temperature may be 85°C or 105°C. After reaching the evaluation temperature, the heating procedure transitions to a isothermal holding phase, in which the standard sample is maintained at the evaluation temperature for a predetermined isothermal duration. The isothermal duration can be adjusted according to the material type and testing purpose, typically, but not limited to, 4 hours, 12 hours, 24 hours, or 48 hours. Throughout the heating and isothermal holding process, the pressure sensor continuously and synchronously records the change in the total gas pressure inside the hot vacuum tank over time at a fixed high sampling frequency (e.g., 0.5Hz, 1Hz, or 2Hz), thereby generating the original characteristic pressure-time curve.

[0040] In an extended embodiment of multi-temperature evaluation, multiple identical standard samples are prepared for the same nonmetallic material. The first standard sample is tested at the aforementioned evaluation temperature T1, the second standard sample is tested at a higher evaluation temperature T2 (e.g., T2 = T1 + 25°C), and the third standard sample is tested at an even higher evaluation temperature T3 (e.g., T3 = T1 + 50°C). By comparing the characteristic pressure-time curves obtained at different evaluation temperatures, the thermal stability of the material can be assessed, and the temperature dependence of its gas release behavior can be inferred. For example, if, with increasing temperature, the peak amplitude of the second mode (bulk diffusion) in the characteristic curve significantly increases and its occurrence time is significantly advanced, while the event frequency of the third mode (defect burst) increases sharply, it indicates that the material has poor thermal stability and is not suitable for long-term use in high-temperature or temperature cycling environments.

[0041] S400. Data Analysis. Extract at least one characteristic parameter for evaluating gas release performance from the characteristic pressure-time curve, and evaluate the gas release performance of the standard sample based on the characteristic parameter.

[0042] After the thermal vacuum test step S300 is completed, the method proceeds to the data analysis step S400. (Refer to...) Figure 1 and Figure 2This step aims to extract quantitative characteristic parameters from the obtained characteristic pressure-time curves and to rapidly evaluate the gas release properties of non-metallic materials based on these parameters. In a preferred embodiment, the data analysis step S400 further includes a signal preprocessing sub-step, a characteristic parameter extraction sub-step, and a gas release mode determination sub-step. Wherein: In the signal preprocessing sub-step, one or more mathematical transformations are performed on the original characteristic pressure-time curve to improve the signal-to-noise ratio and eliminate system errors. Specifically, in an exemplary embodiment, a digital filtering algorithm is first applied to suppress high-frequency noise. Non-limiting filtering methods suitable for this purpose include: moving average filtering, Savitzky-Golay smoothing filtering (e.g., a window width of 51 data points and a polynomial order of 3), or low-pass Fourier filtering. Next, if a background pressure value or background curve was recorded in the aforementioned background acquisition step S200, the background value or background curve is subtracted from the filtered curve to obtain the net release pressure curve. This correction operation effectively removes artifacts introduced by system leakage, venting from the inner wall of the cavity, or temperature drift, ensuring that the net release pressure curve essentially reflects only the gas release contribution of the standard sample itself. In the characteristic parameter extraction sub-step, a set of predefined characteristic parameters is automatically or semi-automatically calculated from the net release pressure curve. According to the teachings of the present invention, the feature parameters are advantageously divided into temporal feature parameters and morphological feature parameters.

[0043] The time-domain characteristic parameters include: (1) peak occurrence time t peak , is defined as the time difference between the start of the isothermal phase (i.e. the moment when the heating process ends, the temperature first reaches and is maintained at the evaluation temperature, denoted as t=0) and the moment when an identifiable local maximum (peak) is located on the net release pressure curve; (2) the pressure fluctuation duration Δt is defined as the total time from t=0 until the pressure value on the curve first decreases and is permanently maintained within ±5% of the final plateau value.

[0044] Morphological characteristic parameters include: (1) Peak amplitude ΔP max , which is defined as the difference between the pressure value at the local maximum and the baseline pressure value at t=0; (2) the curve rise slope k, which is defined as the slope value obtained by linear regression fitting in the interval from the curve rising significantly from the baseline to the peak point; (3) the pressure plateau height P plateau It is defined as the arithmetic mean of the net release pressure curves during the later stages of the isothermal phase (e.g., within the last 10% of the isothermal duration), which is interpreted as the total release amount of the standard sample at the current evaluation temperature.

[0045] In a non-limiting example, for a standard sample of polytetrafluoroethylene (PTFE) heat shrink tubing, the net release pressure curve obtained at 75°C is used to calculate the above parameters as follows: t peak = 47 minutes, Δt = 320 minutes, ΔP max =0.12Pa, k=0.0057Pa / min, P plateau =0.018Pa.

[0046] Based on the extracted feature parameters, the data analysis step S400 further performs a quantitative evaluation of the gas release performance. In a simple evaluation logic, based on ΔP... max Evaluate based on the absolute value: ΔP max The lower the value, the better the material's gas release properties (i.e., the less total gas released). In another, more refined evaluation logic, based on k and P... plateau The combination of values ​​is evaluated as follows: the smaller k is and the higher P is. plateau The lower the value, the better the material's gas release performance is considered.

[0047] More importantly, according to an important aspect of the invention, the data analysis step S400 further includes a release mode determination sub-step. In this sub-step, based on the combination of the time-domain characteristic parameters and the morphological characteristic parameters, each distinguishable peak appearing in the net release pressure curve is classified into at least one of the following three predefined release modes, and each mode is associated with a specific physical mechanism: First mode (surface desorption film type): The peak appears earlier than the first threshold, the shape is symmetrical, and the half-width at half-maximum (WHM) is less than or equal to the second threshold. For example, the peak appearance time t peak ≤30 minutes (from the isothermal start point), half-width at half-maximum of the peak ≤10 minutes; this mode is physically interpreted as a rapid desorption process of gas molecules (such as water vapor) physically adsorbed on or near the surface of a material under thermal excitation.

[0048] The second mode (volume diffusion mode): the peak appears later than the third threshold, exhibits an asymmetrical shape with a slow rise and rapid fall, and its half-width at half-maximum (HWHM) is greater than or equal to the fourth threshold. For example, the peak appearance time t peak The peak duration is ≥60 minutes, exhibiting an asymmetrical slow rise and rapid fall pattern, i.e., the ratio of rise time to fall time is ≥2.0, and the full width at half maximum (FWHM) of the peak is ≥30 minutes. This pattern is physically interpreted as corresponding to the process of gas molecules slowly migrating from the bulk phase of the material to the surface through molecular diffusion (following Fick's law) and eventually being released. This process is closely related to the intrinsic microstructure of the material (such as free volume fraction, crosslinking density, and crystallinity).

[0049] The third mode (defect outbreak mode): peaks appear randomly (the timing of peak appearance is not repeatable in multiple repeated tests, and there is no clear regularity on the time axis), and the amplitude is high (e.g., the peak amplitude ΔP of the peak). max The pressure exceeds a preset multiple (e.g., more than 5 times) of the baseline noise standard deviation of the net release gas pressure curve, and rises or falls rapidly, i.e., the rise time is less than or equal to the fifth threshold (e.g., the rise time of the peak is less than or equal to a preset time, such as ≤ 1 minute). This mode is physically interpreted as corresponding to the instantaneous rupture, explosion, or rapid volatilization of microstructural defects existing inside the material (e.g., tiny bubbles, microcracks, highly volatile impurity particle clusters, or incompletely solidified low molecular weight components enclosed inside the material) when heated, resulting in an explosive release of gas.

[0050] To illustrate this solution more clearly, we will use polytetrafluoroethylene (PTFE) heat shrink tubing as an example: First, three 5cm long polytetrafluoroethylene heat shrink tubing samples were cut, their surfaces were cleaned with anhydrous ethanol and thoroughly dried, and the dried samples were used as standard samples.

[0051] Next, prepare a standard, calibrated thermal vacuum testing device, close the thermal vacuum chamber, start the vacuum pump, and evacuate the thermal vacuum chamber until the internal pressure is below 5.0*10. -3 The pressure remains stable at Pa, and the stable pressure value at this point is recorded as the background pressure value.

[0052] Then, a piece of polytetrafluoroethylene heat shrink tubing is placed on the sample stage inside the vacuum chamber of the thermal vacuum test equipment and a vacuum is drawn. The heating device is started to heat the standard sample to the preset evaluation temperature of 75°C at a preset constant rate of 10°C / min, and the temperature is kept constant at the evaluation temperature for 24 hours. During this process, the pressure change inside the vacuum chamber is continuously recorded to obtain the characteristic pressure-time curve.

[0053] Finally, the obtained characteristic pressure-time curves were analyzed, and the original data was filtered and smoothed. The system background drift (i.e., the background pressure value) was subtracted to obtain the net release pressure curve. Analysis of the time-domain characteristic parameters and morphological characteristic parameters revealed that a small amount of gas was released from the PTFE heat shrink tubing, and the pressure fluctuation was steep. This was likely due to the release of gas adsorbed on defects on the PTFE surface, causing the rapid gas release.

[0054] In addition, the above steps were repeated for the remaining two PTFE heat shrink tubing samples: one was heated to 100°C and held at a constant temperature, and the other was heated to 125°C and held at a constant temperature. Comparing the changes in their characteristic pressures, it can be seen that as the temperature increases, the gas release of the PTFE medium becomes more intense, and the number of rapid gas releases increases.

[0055] Please see Figure 2In order to screen for high-quality materials, as a preferred implementation method, the following steps are also included: S500, Comprehensive Evaluation.

[0056] Specifically, the material of a standard sample can be evaluated based on its gas release pattern. If the gas release pattern of the standard sample is mainly the second mode (the proportion of the second mode is greater than a predetermined proportion), that is, the main part of the curve consists of broad, asymmetrical peaks; and the number of events in the third mode is very small or non-existent (the number of events in the third mode is less than a predetermined number), then the non-metallic material corresponding to the standard sample is evaluated as high-quality, uniform, and stable. Conversely, if a standard sample frequently exhibits the third mode peak, or if its gas release is mainly in the first mode, it indicates that the standard sample may have severe surface contamination or poor internal quality, requiring process investigation.

[0057] Specifically, in the comprehensive evaluation step S500, if the gas release behavior of a standard sample meets the following conditions: its gas release mode is mainly the second mode (bulk diffusion mode) mentioned above, that is, the main part of the curve consists of broad, asymmetric peaks; and the number of discrete events belonging to the third mode (defect burst mode) mentioned above is extremely small (for example, the number of occurrences does not exceed 3 times in a 24-hour test cycle, preferably not more than 1 time, and most preferably 0 times), then the non-metallic material corresponding to the standard sample is evaluated as "high-quality, uniform, and stable". This material is considered to have low defect density, high structural uniformity, and predictable long-term gas release behavior, making it particularly suitable for ultra-high reliability applications such as aerospace, military, and medical implants.

[0058] Conversely, if a standard sample exhibits predominantly Mode 1 (surface desorption) gas release behavior, it indicates that the material may be surface contaminated or insufficiently dried, and the pretreatment intensity should be increased or storage conditions improved. If a standard sample frequently exhibits Mode 3 (defect burst) peaks (e.g., more than once every 6 hours), the material is evaluated as having "microscopic defects or process inhomogeneities" and should be rejected for high-reliability applications, triggering a thorough investigation of the manufacturing process (such as mixing, molding, and curing).

[0059] Please see Figure 3 This is a structural block diagram of an embodiment of the apparatus for evaluating the gas release properties of non-metallic materials according to the present invention. The apparatus for evaluating the gas release properties of non-metallic materials in this embodiment is used to implement the method for evaluating the gas release properties of non-metallic materials as described in the above embodiment. Specifically, the apparatus for evaluating the gas release properties of non-metallic materials in this embodiment includes a vacuum chamber 100, a test module 200, and a data analysis module 300. Wherein: The vacuum chamber 100 is configured to contain a standard sample to be evaluated. In this embodiment, the vacuum chamber is a thermal vacuum vessel in a thermal vacuum apparatus.

[0060] The test module 200 is configured to evacuate the vacuum chamber 100, perform a preset temperature-time program on the standard sample contained therein to heat the standard sample and maintain a constant temperature, and record the change in gas pressure inside the vacuum chamber 100 over time throughout the process, thereby generating a characteristic pressure-time curve. The test module 200 includes a vacuum pump, a heating device, a pressure sensor, and a data processing unit, and is capable of performing a thermal vacuum test according to the above step S300 to obtain a characteristic-time curve for evaluating the gas release properties of the material.

[0061] The data analysis module 300 is used to extract at least one characteristic parameter for evaluating gas release performance from the characteristic pressure-time curve, and to rapidly evaluate the gas release performance of the standard sample based on the characteristic parameter. The data analysis module 300 includes a data processing unit capable of rapidly evaluating the gas release performance of the standard sample according to the above step S400.

[0062] Based on the above embodiments, the present invention has the following technical effects: (i) By analyzing the temporal and morphological characteristics of the characteristic pressure-time curve, this invention can for the first time link the observed gas release behavior to a specific physical mechanism, distinguish the source of gas release, and provide a direct and in-depth scientific basis for material process optimization, defect tracing and failure analysis, overcoming the shortcomings of traditional total quantity indicators that only know what happens but not why.

[0063] (ii) This invention only requires conventional thermal vacuum equipment (without the need for expensive gas composition analysis instruments such as quadrupole mass spectrometers), which greatly reduces equipment investment and evaluation costs, making the method easy to popularize and apply in production lines, materials research and development departments and quality inspection laboratories.

[0064] (III) By monitoring the pressure changes caused by the release of gas from materials in a confined space, this invention can sensitively distinguish the differences in gas release from different materials, providing a quantitative basis for quality comparison in material selection and process optimization.

[0065] (iv) Compared with traditional quality loss testing that takes several days or even weeks, the entire testing and data analysis process of this invention can be completed in a few hours, which greatly improves the evaluation efficiency and is suitable for rapid sampling on the production line or preliminary screening of material suppliers.

[0066] (v) By testing the same material at different evaluation temperatures and comparing its characteristic curves, this invention can provide additional information about the thermal stability of the material and the trend of the release activation energy, which is something that existing single-temperature point total quantity testing methods cannot achieve.

Claims

1. A method for evaluating the gas release properties of non-metallic materials, characterized in that, Includes the following steps: Perform a thermal vacuum test: Place the standard sample into a vacuum chamber, evacuate the vacuum chamber, heat the standard sample according to a preset program and keep it at a constant temperature after heating. Record the pressure change in the vacuum chamber over time during the heating process and / or the constant temperature stage to obtain the characteristic pressure-time curve. Data analysis: Extract at least one characteristic parameter for evaluating gas release from the characteristic pressure-time curve, and evaluate the gas release of the standard sample based on the characteristic parameter.

2. The method for evaluating the gas release properties of non-metallic materials as described in claim 1, characterized in that: Before the step of conducting the thermal vacuum test, the following steps are also included: Obtaining the background pressure: Under no-load conditions, the vacuum chamber is evacuated and a stable background pressure value is obtained; Prior to the data analysis step, the following steps are also included: The characteristic pressure-time curve is filtered and smoothed, and the background pressure value is subtracted.

3. The method for evaluating the gas release properties of non-metallic materials as described in claim 1, characterized in that: Before the step of conducting the thermal vacuum test, the following steps are also included: Sample pretreatment: The non-metallic material sample to be tested is cleaned, dried and cut into a uniform shape and surface area to obtain a standard sample.

4. The method for evaluating the gas release properties of non-metallic materials as described in claim 1, characterized in that: The feature parameters include temporal feature parameters and / or morphological feature parameters; The time-domain characteristic parameters include: the time of appearance of the pressure value peak relative to the isothermal starting point and the duration of pressure fluctuations inside the vacuum device. The morphological characteristic parameters include: the peak value of the pressure wave, the slope of the curve, and the height of the pressure plateau after the curve tends to stabilize in the later stage of isothermal operation.

5. The method for evaluating the gas release properties of non-metallic materials as described in claim 4, characterized in that, The data analysis steps include: The gas release properties of non-metallic materials are evaluated based on the peak value of the pressure wave; the lower the peak value, the better the gas release properties. The gas release properties of non-metallic materials are evaluated based on the slope of the curve; the gentler the slope, the better the gas release properties. The gas release properties of non-metallic materials are evaluated based on the slope of the curve and the height of the pressure plateau. The smaller the slope and the lower the height of the pressure plateau, the better the gas release properties of the non-metallic material. The pressure platform height represents the total amount of gas that can be released from the standard sample at the evaluation temperature.

6. The method for evaluating the gas release properties of non-metallic materials as described in claim 4, characterized in that, The data analysis steps further include: analyzing the pressure peaks appearing in the characteristic pressure-time curve based on the time-domain characteristic parameters and morphological characteristic parameters, thereby determining the gas release mode of the standard sample and associating it with the specific physical mechanism; wherein, the gas release mode includes at least: The first mode is defined as a peak that appears earlier than the first threshold, has a symmetrical shape, and a half-width at half-maximum (WHM) less than or equal to the second threshold. This mode corresponds to the rapid desorption of gases adsorbed on or near the surface of the material. The second mode is defined as a wave peak that appears later than the third threshold, has an asymmetrical shape with a slow rise and a fast fall, and has a half-width at half-maximum greater than or equal to the fourth threshold. This mode corresponds to a gas release process controlled by bulk diffusion of the material. The third mode is defined as a peak occurrence time that is random, a peak amplitude that exceeds the fifth standard deviation of the baseline noise, and a rise time that is less than or equal to the fifth threshold. This mode corresponds to the instantaneous rupture of internal defects in the material or the bursting of highly volatile impurity particles.

7. The method for evaluating the gas release properties of non-metallic materials as described in claim 6, characterized in that, It also includes a comprehensive evaluation step: if the proportion of the second mode in the gas release mode of the standard sample is greater than a predetermined proportion, and the number of events belonging to the third mode is less than a predetermined number, then the non-metallic material corresponding to the standard sample is evaluated as high quality, uniform and stable.

8. The method for evaluating the gas release properties of non-metallic materials as described in claim 1, characterized in that, The preset procedure includes: heating the standard sample to a preset evaluation temperature at a preset constant heating rate, and maintaining the temperature at the evaluation temperature for a predetermined duration.

9. The method for evaluating the gas release properties of non-metallic materials as described in claim 8, characterized in that: The evaluation temperature is at least one. When there are multiple evaluation temperatures, the thermal stability of the material is evaluated by comparing the characteristic pressure-time curves of the same material at different evaluation temperatures.

10. A device for evaluating the gas release properties of non-metallic materials, characterized in that, include: A vacuum chamber, configured to contain standard samples to be evaluated; The test module is configured to evacuate the vacuum chamber, heat the standard sample according to a preset program and keep it at a constant temperature, and record the pressure change in the vacuum chamber over time during the heating process and / or the isothermal stage after heating, thereby generating a characteristic pressure-time curve. A data analysis module is configured to extract at least one characteristic parameter for evaluating gas release from the characteristic pressure-time curve, and to rapidly evaluate the gas release of the standard sample based on the characteristic parameter.

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