Reclaimed rubber inorganic component rapid detection method and system based on X-ray photoelectron spectroscopy and program product

Abstract

The invention relates to the technical field of rubber detection, in particular to a reclaimed rubber inorganic component rapid detection method and system based on X-ray photoelectron spectroscopy and a program product. The method comprises the following steps: carrying out low-speed constant-temperature combustion on a reclaimed rubber sample to remove an organic phase, obtaining inorganic ash, tabletting to form a conductive test piece, and determining valence state distribution of elements such as Si, Zn and Na through XPS. Quantitative indexes such as a silicon dioxide index, a coupling agent residue index and a metal oxide index are constructed according to a spectrogram fitting result, and rapid evaluation of desulfurization sufficiency, the coupling agent retention degree and the alkali salt purification efficiency is achieved. The method has the advantages of being short in detection period, traceable in result, strong in correlation between evaluation indexes and mechanical properties and the like, and is suitable for reclaimed rubber quality grading and online formula adjustment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber detection, and particularly relates to a method, system and program product for rapid detection of inorganic components of reclaimed rubber based on X-ray photoelectron spectroscopy. BACKGROUND

[0002] About 200 million waste tires are generated worldwide each year, and more than 30 million tons of waste tires are generated in China each year. Reclaimed rubber is an important way of resource utilization of waste tires, and its preparation process usually goes through the links of cracking, devulcanization, refining and reinforcement. Whether the devulcanization and post-cleaning can fully strip the residual sulfur network chain, maintain the integrity of the reinforcing agent, and remove the introduced alkali salt at the same time directly determines the physical and mechanical properties of the reclaimed rubber and the compatibility of the downstream rubber formula. However, the monitoring of the above-mentioned key chemical information on the production line still stays at the macroscopic index level, and cannot timely feedback the microscopic formula change, thereby restricting the high-value application of the industry.

[0003] The industry often uses ash content (ASTM D297), total sulfur, Mooney viscosity, tensile strength and other indicators to evaluate the batch difference of reclaimed rubber. Taking ASTM D297 as an example, ash testing needs to be burned at 550-600°C, and then the residue is weighed; this method can only get the total percentage of inorganic matter, and cannot distinguish components such as SiO2, ZnO, metal soap and carbon black residue, and if the burning temperature is not strictly controlled, Zn and Na will be volatilized, making the measured value distorted. The mechanical and rheological parameters are also affected by the particle size of the previous cracking, the oil supplementing amount, the mixing temperature and other factors, and it is difficult to separately reflect the devulcanization or cleaning effect, resulting in that the production adjustment depends on off-line test piece testing and experience judgment, and the feedback period is often more than 4 hours.

[0004] The reclaimed rubber terminal is mostly used for tread, sidewall or high-end rubber products, and needs accurate reinforcement design. Overdevulcanization will cause the breakage of coupling agent (Si-O-R) bond and the silanolization of SiO2; insufficient cleaning will also leave alkali salt such as Na2S and Na2CO3, affecting the dynamic performance of vulcanized rubber. Therefore, the industry urgently hopes to obtain a micro-area inorganic quantitative method which can be completed within tens of minutes after the devulcanization / cleaning process, so as to quickly grade, guide the amount of vulcanization reinforcing agent and reduce batch fluctuations.

[0005] XPS can analyze the valence state and chemical bond of elements within a few nanometers, and is a powerful tool for laboratory research on the surface chemistry of rubber. Literature reports that XPS is used to track the O and S valence state changes of carbon black on the surface of waste tire cracking to evaluate the activation degree. However, there are two big problems in directly applying XPS to reclaimed rubber particles containing more than 30% carbon black and plasticizing oil: 1. charging effect - the high-resistance organic matrix accumulates charges under the vacuum beam, causing baseline drift and peak shift >1eV; 2. vacuum pollution - incomplete removal of oil stains will cause C contamination on the surface of the sample, and the C 1s peak will overlap with the Zn 2p3 / 2 peak. -8 –10 -9Continuous evaporation and deposition of thin films in the mbar environment reduce the signal-to-noise ratio.

[0006] Researchers have tried to use electron / ion dual gun neutralization, sample back evaporation of gold film, low-energy Ar + Sputtering or Ar-cluster sputtering and other means to inhibit charging and contamination, but all have high cost, long time-consuming or risk of chemical reduction to fragile oxides. Related literature points out that long-time Ar + Bombardment can induce ZnO reduction to Zn 0 , and even trigger migration and redeposition, leading to misjudgment of valence state.

[0007] Although the prior art shows the advantages of XPS in the analysis of inorganic oxide valence state, the charging / pollution barrier of direct testing on the surface of reclaimed rubber, and the chemical damage caused by Ar + Sputtering makes it difficult to be industrialized; and the combination of traditional ash method and XPS also faces the bottleneck of Zn / Na volatilization, insufficient conductivity, lack of standardized index, etc. In summary, the industry urgently needs a rapid detection scheme that integrates low-speed constant-temperature combustion, tablet conductivity, fine peak fitting and multi-dimensional index modeling, to bridge the technical gap between macro ash method and high-precision XPS, and to realize objective and traceable evaluation of reclaimed rubber desulfurization sufficiency, coupling agent retention and alkali salt purification efficiency, and to provide basic data for tire green recycling and formula intelligent optimization. SUMMARY

[0008] To solve the above technical problems, the present application provides a rapid detection method for inorganic components of reclaimed rubber based on X-ray photoelectron spectroscopy, aiming to establish a rapid, objective and standardizable evaluation method for the desulfurization quality, coupling agent retention and inorganic salt purification degree of reclaimed rubber. By constant-temperature combustion of the sample into ash and direct tablet-XPS testing, the charging and surface pollution problems are completely eliminated, without the need for expensive ion beam etching, and the valence state and other related information of key components such as SiO2, ZnO, Na2O and organic silicon residues can be obtained in a short time. The inventors further propose multi-dimensional quantitative indexes such as silicon index SiI and coupling agent residue index CARI, to realize one-key optimization of laboratory-production line and strong correlation with mechanical properties, providing an innovative tool for reclaimed rubber quality grading, formula reinforcement and process online adjustment, and filling the technical gap between ash method and conventional XPS.

[0009] To achieve the above purpose, the present application adopts the following technical solutions:

[0010] A rapid detection method for inorganic components of reclaimed rubber based on X-ray photoelectron spectroscopy, which comprises the following steps in sequence:

[0011] a) Sampling: randomly take 1-5g of sample from the target batch of reclaimed rubber particles;

[0012] b) Pre-drying: 90-110℃, 0.3-1.0ms -1 Drying under air flow for 1-3h;

[0013] c) Temperature programmed combustion ashing: ramping at 5-20℃min -1 Ramping to 500-900℃ and holding for 1-3h, cooling <50℃ to take out ash to inhibit Zn and Na volatilization;

[0014] d) Pulverization: transferring ash into anhydrous agate mortar for grinding;

[0015] e) Tabletting preparation: placing ash into a copper die cavity, applying pressure of 2-10MPa to form self-supporting conductive tablets with thickness of 1-2mm and diameter of 10-20mm;

[0016] f) XPS testing: performing energy spectrum scanning on the tablet sample in a 300μm×700μm area using monochromatic Al Kα light source under vacuum degree <1×10 -9 mbar;

[0017] g) Data processing: taking C-C bond 284.8eV as internal standard, fitting Si, Zn, Na spectra using Shirley background deduction combined with Gaussian-Lorentz mixed function, recording peak area, and calculating silica index SiI, coupling agent residual index CARI, Zn, Na metal oxide index ZnOI / NaI multi-dimensional quantitative index for characterizing desulfurization sufficiency, coupling agent retention, and alkali salt purification efficiency.

[0018] As preferred, the copper die cavity in step e) is detachable structure, and mirror-polished layer is set on the die inner wall to ensure the flatness and conductivity of the tablet surface.

[0019] As preferred, the XPS energy resolution in step f) is set to 0.1-0.2eV, and the analysis depth is controlled at 1-10nm by adjusting the collection angle.

[0020] As preferred, the calculation formula of each index in step g) satisfies:

[0021] SiI=A(SiO2103.3eV) / [A(SiO2103.3)+A(R-Si-O102.2)],

[0022] CARI=A(R-Si-O102.2) / denominator, wherein A(x) is the fitting peak area normalized by FWHM weight.

[0023] As preferred, a platform of 350℃±10℃ is set in the temperature ramping section of step c) for 15-30min to further oxidize volatile silicone residues.

[0024] Further, the application also provides a quick detection system of inorganic components of reclaimed rubber based on XPS, which is used to realize the method, comprising:

[0025] a high-temperature furnace with 0-1000℃ programmed temperature control and residual oxygen detection;

[0026] a tabletting device with a detachable copper mold and a 50kN hydraulic machine;

[0027] an XPS analyzer comprising a monochromatic AlKα light source, an energy analyzer, an ultrahigh vacuum cavity and a 300μm×700μm variable aperture;

[0028] a data processing unit pre-installed with spectrum peak fitting and index calculation software, which is used to process the scanning data and calculate the half-peak width, and automatically output SiI, CARI, ZnOI and NaI.

[0029] The data processing unit communicates with the factory MES system or the laboratory LIMS system, and can link the index results with the mechanical property database for online formula adjustment.

[0030] As preferred, the XPS analyzer is equipped with a conductive elastic loading clamp, which can complete the loading and unloading of the sample within <2min and ensure stable grounding during the test.

[0031] Further, the application also provides a computer readable storage medium having a computer program stored thereon, which realizes the spectrum fitting and index calculation of step g) in the method when executed by a processor.

[0032] Further, the application also provides a computer program product comprising a computer program or instructions, which realizes the spectrum fitting and index calculation of step g) in the method when executed by a processor.

[0033] The application realizes the rapid, objective and traceable quantitative evaluation of inorganic oxides in reclaimed rubber for the first time, and significantly improves the accuracy and timeliness of the quality grading and production process control of reclaimed rubber. The application has the following technical effects:

[0034] 1. Eliminate charging and oil stain interference completely: burn the organic matrix at 500-900℃ at a low constant temperature to convert it into conductive ash, avoid peak shift and signal-to-noise ratio decay caused by the volatilization of carbon black and plasticizing oil under vacuum, and ensure the stability of the spectrum.

[0035] 2. Maintain the original state of key oxides and inhibit volatilization: through a heating rate of ≤20℃·min -1 and a 350℃ platform section, effectively reduce the loss of volatile components such as Zn and Na, and ensure that the valence state measured by XPS is consistent with the actual state after desulfurization / cleaning.

[0036] 3. Constructing multi-dimensional quantitative evaluation index: introducing SII, CARI, ZnOI, Nal and other normalization indexes based on peak area-FWHM, which can intuitively determine the sufficiency of desulfurization, the retention of coupling agent and the purification efficiency of alkali salt, and establish strong correlation mapping with mechanical properties.

[0037] In summary of the above sub-effects, the application not only solves the industry pain points of "difficulty in charging, quantification and standardization" of reclaimed rubber XPS detection, but also provides an inorganic component evaluation method closely related to mechanical properties in a low-cost and short-cycle manner, thereby laying a reliable technical foundation for reclaimed rubber quality grading, formula reinforcement optimization and intelligent production control. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a Si2p spectrum;

[0039] Figure 2 is a Zn2p spectrum;

[0040] Figure 3 is a Na1s spectrum. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0042] I. Equipment composition and installation

[0043] 1. Pretreatment module

[0044] Muffle furnace: maximum temperature 1000℃, programmable temperature rise; built-in thermocouple with ±2℃ precision; furnace volume ≥5L. Air flow control valve: 0-2ms -1 Continuously adjustable, used for air replacement in the drying stage.

[0045] 2. Sample forming module

[0046] Anhydrous agate mortar: grinding particle size up to 10μm.

[0047] Copper detachable mold: inner diameter 13mm, mirror polished; silver-graphite composite conductive gasket embedded in the upper and lower mold covers.

[0048] Hydraulic tablet press: maximum pressure 50kN; matched with a film type pressure sensor to monitor the pressure curve in real time.

[0049] 3. XPS test module

[0050] Monochromated Al Kα XPS: light source power 150 W, analyzer pass through cone diaphragm to limit 300 pm x 700 pm spot beam; energy resolution 0.1 eV; vacuum degree < 1 x 10 -9 mbar.

[0051] Elastic conductive fixture: one-key clamping copper tablet, ensuring good grounding of the back surface and the sample stage.

[0052] 4. Data processing and interface

[0053] Spectrum fitting software: built-in Shirley background, Gaussian-Lorentz correction and exponential algorithm module; PLC-OPCUA protocol and factory MES interface.

[0054] II. Sample preparation and ashing

[0055] 1. Random sampling

[0056] From the regenerated rubber particles of the batch to be tested, use a rotary sampler to collect the mixture at three points, and then divide it into 2.0 g by quartering.

[0057] 2. Pre-drying

[0058] Spread 2.0 g of the sample evenly in a Φ60 mm quartz crucible, with a thickness of ≤3 mm. Place it in a 100°C muffle furnace pre-chamber, with an air flow rate of 0.5 ms -1 , dry for 120 min; record the mass m0.

[0059] 3. Low-speed constant-temperature combustion ashing

[0060] Move the crucible into the main body of the muffle furnace and set the temperature curve:

[0061] 0 - 350°C: 10°C / min -1 ;

[0062] 350°C holding: 20 min (to catalyze the oxidation of plasticizing oil and volatile silane);

[0063] 350 - 550°C: 10°C / min -1 ;

[0064] 550 - 800°C: 5°C / min -1 ;

[0065] 800°C holding: 60 min.

[0066] Natural cooling to <50°C before removal; measure the ash mass m1(typical yield 35% - 45%).

[0067] Note: Multi-stage temperature rising and 350℃ platform design can ensure the complete oxidation and dispersion of C and S elements while keeping ZnO and Na2O stable.

[0068] 4. Pulverization and sieving

[0069] Lightly press and grind in anhydrous agate mortar for 5 min to obtain ash D 50 <20 μm; pass through a 200-mesh titanium screen.

[0070] III. Tablet preparation

[0071] Weighing: accurately weigh 0.150 g of ash into a copper mold.

[0072] Pressing: apply a constant pressure of 6 MPa for 60 s in a hydraulic tablet press, and after unloading, take out a self-supporting thin sheet with a diameter of Φ13 mm and a thickness of about 1.5 mm.

[0073] Conductivity check: test the surface resistance of the tablet with a four-probe tester, and if it is <10 Ω-1, it can enter the XPS stage. If it does not meet the standard, re-press in the mold at 8 MPa and re-check.

[0074] IV. XPS test procedure

[0075] 1. Clamping and vacuuming

[0076] Place the copper tablet in the elastic conductive fixture 310 and lock it tightly to ensure that the copper base is in contact with the spring contact of the sample stage. After closing the chamber, start the molecular pump for 20 min, and the vacuum degree stabilizes at 8 × 10 -10 mbar.

[0077] 2. Energy region scanning

[0078] Full-spectrum fast scanning: 0-1200 eV, step 1 eV, confirm no high-intensity C1s signal;

[0079] Narrow region high resolution: Si2p, Zn2p3 / 2, Na1s, step 0.05 eV, accumulate 10 times to improve S / N;

[0080] Analysis depth: 1-10 nm;

[0081] Use neutralized electron beam 1 mA / 3 eV for residual charge compensation.

[0082] 3. Instrument drift calibration

[0083] Collect Cu3p(75 eV) internal standard to confirm that the drift is ≤0.1 eV; if it is out of tolerance, use software displacement correction and re-scan the target narrow region.

[0084] V. Spectrum processing and index calculation

[0085] 1. Background subtraction and peak fitting (step S301)

[0086] Shirley background was selected; 70% Gaussian / 30% Lorentzian mixed function was used for each element spectrum; SiO2peak position was constrained at 103.0-103.6 eV, R-Si-O peak position at 101.8-102.8 eV; ZnO at 1022.2-1023.6 eV, Zn 0 at 1020.8-1022.0 eV; Na2O at 1071.0-1072.4 eV, Na + at 1070.0-1070.8 eV.

[0087] 2. Core index algorithm (step S302)

[0088] Exponent Physical meaning Calculation formula Si I Silica retention [A(SiO2) / (A(SiO2)+A(R-Si-O))] CARI Coupling agent retention [A(R-Si-O) / (A(SiO2)+A(R-Si-O))] ​ Zn OI Zinc oxide integrity [A(ZnO) / (A(ZnO)+A(Zn 0 ))]]> NaI / Na + I]]> Metallic sodium and sodium ion distribution [A(Na2O) / (ΣNa); A(Na + ) / (ΣNa)]]>

[0089] where A(x) is the value of corresponding peak area after FWHM weight correction. The software retains the index to three decimal places and synchronously transmits it to the MES.

[0090] 3. Quality grading rules

[0091] Grade A: SiI≥0.70 and CARI≤0.30; ZnOI≥0.80; Natotal≤0.10.

[0092] Grade B: SiI0.50-0.70 or CARI0.30-0.45; ZnOI0.60-0.80.

[0093] Grade C: SiI<0.50 or ZnOI<0.60; Natotal>0.10.

[0094] The MES system automatically calls the reinforcement additive increment and cleaning time adjustment strategy accordingly.

[0095] Example 1

[0096] 1. Sample source and preparation

[0097] Process background: A certain tire retreading plant uses a continuous wet devulcanization section (170℃, 1.5MPa, 90min) to process 80mesh tire powder, aiming to prepare high-performance tread grade reclaimed rubber.

[0098] Random sampling: 100g of particles were taken every 5min on the devulcanization outlet cooling belt, and after blending, a quartering method was used to obtain 2.0g of representative samples.

[0099] Pre-drying: 100℃, air flow rate 0.5ms -1 , time 120min.

[0100] Isothermal combustion: temperature program as specified in the invention (10 °C min -1 → 350 °C plateau 20 min → 5 °C min -1 to 800 °C for 60 min), cooled to 40 °C and ashed.

[0101] Grinding and tabletting: the ash was ground in a marvered mortar < 20 pm, 0.150 g was weighed in a copper die and compressed at 6 MPa for 60 s to obtain a conductive thin sheet of Φ 13 mm and 1.5 mm thick.

[0102] 2. XPS test conditions

[0103] Parameter Set value Excitation source Al K a, power 150 W Analysis area 300 pm x 700 pm Energy resolution 0.1 eV Vacuum degree 8 x 10 -10 mbar Charge correction 284.8 eV (C-C) internal standard

[0104] 3. Spectrum fitting and index calculation

[0105]

[0106]

[0107] Index calculation:

[0108] SiI = A(Si02) / [A(Si02) + A(R-Si-O)]

[0109] CARI = A(R-Si-O) / same denominator

[0110] ZnOI = A(ZnO) / [A(ZnO) + A(Zn 0 )], ZnI is the complementary value

[0111] NaI, Na + I are the same.

[0112] 4. Results and discussion

[0113] 1) Coupling agent residual: CARI is 0.659, meaning that > 65% of the silicon is still in organosilicon state, indicating that the wet desulfurization has preserved the coupling agent skeleton and the subsequent reinforcement demand of the compound is low.

[0114] 2) Silica retention: SiI is only 0.341, deducing that part of the outer silicon-oxygen network of the coupling agent has been destroyed, which coincides with the occasional increase in pH of the NaOH washing solution in the production records.

[0115] 3) Zinc metal valence: ZnI is as high as 0.916 and ZnOI is only 0.084, indicating that ZnO has almost been reduced to Zn 0—— excess vulcanization activator is reduced by hydrogen sulfide in the desulfurization stage. This information suggests that ZnO needs to be supplemented or the vulcanization system needs to be adjusted.

[0116] 4) Alkali metal residual: Na+ I / NaI ratio ≈ 1.18, showing that although the cleaning step removed part of the metallic sodium, 46% remained in the form of metal or alkali salt, which may lead to the risk of vulcanization reversal in the subsequent process.

[0117] 5. Mechanical correlation verification

[0118] The 300% modulus of the vulcanized sheet of the reclaimed rubber prepared in the same batch (100 phr of standard rubber content) was 7.8 MPa, which was 18% lower than that of the historical A-grade batch (SiI≥0.70, ZnOI≥0.80, Natotal≤0.10). It was fully proved that the SiI, ZnOI and Na indexes output by the method could early warn the mechanical performance degradation trend, and the effectiveness and practical value of the technology were verified.

[0119] The above describes the embodiments of the present application, and through the above description of the disclosed embodiments, the person skilled in the art can realize or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for rapid detection of inorganic components in reclaimed rubber based on X-ray photoelectron spectroscopy, characterized in that, The method comprises the following steps in sequence: a) Sampling: randomly take 1-5 g of sample from the target batch of reclaimed rubber particles; b) Pre-drying: 90-110°C, 0.3-1.0 ms -1 Drying under air flow for 1-3 h; c) isothermal combustion ashing: 5 - 20 °C min -1 to 500 - 900 °C and isothermal for 1 - 3 h, cooled < 50 °C and the ash was removed to suppress Zn and Na volatilization; d) Pulverization: transfer the ash into a water-free agate mortar and grind; e) Tablet preparation: place the ash in a copper mold cavity, apply pressure of 2-10 MPa to form a self-supporting conductive tablet with a thickness of 1-2 mm and a diameter of 10-20 mm; f) XPS test: Energy spectrum scanning of the tablet sample in a 300 pm x 700 pm area was performed under a vacuum degree < 1 x 10 -9 mbar condition using a monochromatic Al K alpha light source; f) XPS test: Energy spectrum scanning of the tablet sample in a 300 pm x 700 pm area was performed under a vacuum degree < 1 x 10 -9 mbar condition using a monochromatic Al K alpha light source; g) Data processing: use the C-C bond at 284.8 eV as an internal standard, use Shirley background subtraction combined with Gaussian-Lorentz mixed function fitting of Si, Zn, and Na spectra, record the peak area, and calculate the multi-dimensional quantitative indexes of the silicon dioxide index SiI, the coupling agent residual index CARI, and the Zn and Na metal oxide indexes ZnOI / NaI, which are used to characterize the desulfurization sufficiency, coupling agent retention, and alkali salt purification efficiency.

2. The method of claim 1, wherein, The copper mold cavity in step e) is of a detachable structure, and a mirror-polished layer is arranged on the inner wall of the mold to ensure the flatness and conductivity of the tablet surface.

3. The method of claim 1, wherein, In step f), the energy resolution is set to 0.1-0.2 eV, and the analysis depth is controlled at 1-10 nm by adjusting the collection angle.

4. The method of claim 1, wherein, In step g), the calculation formulas of the indexes satisfy: SiI=A(SiO2103.3eV) / [A(SiO2103.3)+A(R-Si-O102.2)], CARI=A(R-Si-O102.2) / same denominator, where A(x) is the fitting peak area, normalized by FWHM weight.

5. The method of claim 1, wherein, In the temperature rising section of step c), a platform of 350℃±10℃ is set for 15-30 min to further oxidize volatile silicone residues.

6. A system for rapid detection of inorganic components of XPS based recycled rubber, characterized by, The system is used to implement the method of any one of claims 1-5, comprising: a high-temperature furnace with 0-1000℃ program temperature control and residual oxygen detection; a tabletting device with a detachable copper mold and a 50kN hydraulic press; an XPS analyzer including a monochromatic AlKα light source, an energy analyzer, an ultra-high vacuum chamber, and a 300µm×700µm variable aperture; a data processing unit pre-installed with spectral peak fitting and index calculation software for peak separation processing and half-peak width calculation of scanning data, and automatically outputting SiI, CARI, ZnOI, and NaI.

7. The system of claim 6, wherein, The data processing unit communicates with the factory MES system or the laboratory LIMS system, and can link the index results with the mechanical property database for online formulation adjustment.

8. The system of claim 6 or 7, wherein, The XPS analyzer is equipped with a conductive elastic loading clamp, which can complete sample loading and unloading within <2 min and ensure stable grounding during testing.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the spectral fitting and index calculation of step g) in the method of any one of claims 1-5.

10. A computer program product comprising computer programs or instructions, characterized in that, The computer program or instructions are executed by the processor to implement the spectral fitting and index calculation of step g) in the method of any one of claims 1-5.

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