1 Introduction
1.1 The Importance and Wide Application Fields of Rubber
Rubber is a crucial industrial raw material that is utilized extensively in both daily life and industrial production. Rubber is an essential material for making a variety of tires, constructing sealing strips, wire and cable insulation layers, etc. since it has high flexibility, wear resistance, insulation, and other qualities. The use of rubber goods is becoming more widespread as science and technology advance, including a wide range of sectors including automotive, aerospace, medical, and electrical appliances.
1.2 The necessity of effective testing of rubber quality
The productivity and product quality of downstream sectors are directly impacted by the performance and quality of rubber goods. For this reason, thorough and precise rubber quality testing is essential. While the fundamental performance indicators of rubber may be obtained using conventional physical and chemical testing methods, the sluggish and destructive detection speed makes it challenging to fulfill the demands of contemporary industrial production. The development of novel, quick, non-destructive, and extremely sensitive rubber detecting technology is therefore desperately needed in order to guarantee the quality stability of rubber goods and boost the productivity of downstream sectors.
2. Traditional physical and chemical detection methods
2.1 Traditional rubber detection methods
(1) Physical testing: to assess the mechanical qualities of rubber, methods include density measuring, tensile testing, and hardness testing.
(2) Chemical testing: methods used to ascertain the chemical composition and structure of rubber include elemental analysis, thermal analysis, infrared spectroscopy, and others.
The fundamental performance indicators of rubber can be obtained using these approaches, but they have drawbacks such sluggish detection speeds and the requirement for destructive sample preparation, which makes it challenging to fulfill the real-time monitoring requirements of contemporary industrial production.
2.2 Emerging advanced detection technologies in recent years
New non-destructive, quick, and extremely sensitive rubber detecting technologies have surfaced recently in an effort to get beyond the drawbacks of conventional detection techniques. These technologies primarily consist of:
(1) Infrared spectroscopy technology: Rubber's chemical composition may be swiftly ascertained by doing qualitative and quantitative analysis on rubber using infrared spectroscopy.
(2) Raman spectroscopy technology: Richer chemical information may be obtained by conducting chemical identification and structural analysis of rubber using the Raman scattering effect.
(3) Fluorescence spectroscopic technology: quick identification based on the fluorescent characteristics of certain rubber constituents.
Using near-infrared spectroscopy technology, one may quickly and non-destructively analyze the components of rubber.
These newly developed optical detecting technologies offer efficient online and real-time rubber quality monitoring tools.
3. Rubber quality monitoring based on optical detection technology
3.1 Principles and characteristics of optical technology
Principles of optical technology
The interaction of light and matter is the foundation of optical detecting technologies. Rubber materials are susceptible to a variety of optical phenomena, including absorption, scattering, reflection, and transmission. Rubber quality may be evaluated by evaluating these optical characteristics since they are intimately linked to the material's chemical composition and physical characteristics.
Optical technical characteristics
- Non-destructive: Optical testing is appropriate for non-destructive testing since it won't harm rubber materials.
- Rapidity: Optical detection technology is appropriate for quick quality evaluation since it can provide detection findings in a timely manner.
- High sensitivity: ideal for accurate quality control since it can pick up on even the smallest changes.
- Multi-parameter detection: It offers thorough material information and is capable of simultaneously detecting several physical and chemical characteristics.
3.2 Application of infrared spectroscopy technology in rubber detection
Introduction to infrared spectroscopy technology:
The molecular structure of materials may be effectively analyzed with the use of infrared spectroscopy technology. It is possible to determine a material's chemical makeup and structural details by measuring how much infrared light it absorbs.
Application of infrared spectroscopy technology in rubber testing:
Chemical structure analysis: Infrared spectroscopy may be used to identify rubber's functional groups and chemical bonds.
Analyze rubber for plasticizers, antioxidants, and other chemicals using additive analysis.
Monitoring of aging and deterioration: Use spectral changes analysis to track the aging and degradation of rubber.
Controlling the quality of the rubber production process in real time to guarantee product uniformity is known as quality control.
3.3 Sample preparation and spectral data collection
Sample setup:
Rubber samples must be sectioned, ground, or dissolved in order to prepare them for spectroscopic examination.
Gathering spectral data:
When gathering data, use an infrared spectrometer and select the proper wavelength range and resolution.
Techniques for preparing and analyzing spectral data
Preprocessing spectral data:
include operations including noise reduction, spectral smoothing, normalization, and background correction.
Method of analysis:
Utilize chemometric techniques for data analysis, such as partial least squares regression (PLSR), principal component analysis (PCA), etc.
3.4 Typical application cases
Rubber aging observation:
Using infrared spectroscopy, track the spectral properties of rubber samples over time to assess the level of aging.
Adding to the analysis
To assure formulation correctness, use infrared spectroscopy technology to identify and quantify particular additives in rubber.
Case of quality control:
On the production line, keep an eye on the rubber's quality in real time and act fast to address any variations in the process.
Troubleshooting:
Rubber spectral data analysis may be used to detect issues like frost spitting, wax spitting, and other production-related issues.
4. Application of Raman spectroscopy technology in rubber detection
4.1 Principles and advantages of Raman spectroscopy technology
Principle of Raman spectroscopy technology:
The Raman scattering phenomenon, which was discovered by Indian scientist C.V. Raman, is the foundation of Raman spectroscopy. The majority of light that strikes a molecule will be dispersed at the same frequency, a phenomenon known as Rayleigh scattering; however, a little portion of light will be scattered because of Raman scattering is the process of changing the frequency of scattered light by contact with the vibrational energy levels of molecules. This is the cause of energy transfer.
Advantage:
- Non-destructive: Information may be obtained without destroying or changing the sample.
- Molecular specificity: The capacity to offer comprehensive details on a molecule's vibrational modes.
- Quick detection: It is possible to rapidly ascertain the sample's structural details and chemical makeup.
- Adaptability: Low requirements on sample form, suitable for solid, liquid, and gas samples.
preparing the sample and gathering the data
Preparing the Sample:
Rubber samples often require cleaning, drying, and maybe cutting or sanding in order to provide a smooth surface.
In order to facilitate Raman spectroscopy experiments, the rubber might need to be dissolved or thinned out for particular uses.
Gathering of data:
After scanning the material with a Raman spectrometer, choose the right laser power and wavelength.
Gather Raman scattering spectra and note the strength of scattered light at various wave numbers.
Qualitative and quantitative rubber components and data analysis
Data interpretation:
By examining the distinctive peaks in the Raman spectrum, one may determine the chemical bonds and functional groups present in rubber.
To do a qualitative study of the constituents, compare the Raman spectrum database of known chemicals.
Both quantitative and qualitative:
Intensity ratios of distinctive peaks are used in quantitative analysis.
To increase the precision of quantitative analysis, use chemometric techniques like partial least squares (PLS) and principal component analysis (PCA).
Common use cases
Rubber Aging and Monitoring of Degradation:
To evaluate aging and performance deterioration, track chemical changes in rubber over time using Raman spectroscopy.
Analysis of rubber additives:
Use Raman spectroscopy to locate and measure rubber additives such as plasticizers and antioxidants.
Rubber quality assurance:
On the production line, Raman spectroscopy technology is used for real-time product quality monitoring.
Rubber substance identification:
To distinguish between various rubber material kinds or sources, use Raman spectroscopy.
5. Application of other optical detection technologies in rubber detection
luminosity spectroscopy
The technology behind fluorescence spectroscopy principle:
The principle behind fluorescence spectroscopy technology is that materials that have been stimulated by high-energy light will eventually release lower-energy light. The type, quantity, and environment of the fluorophores in a substance may all be determined using fluorescence spectroscopy.
Utilization in the rubber testing process:
- Identify fluorescent additives or impurities in rubber by using fluorophore identification.
- Monitoring of aging: Variations in fluorescence characteristics can reveal how old rubber is.
- Identification of defects: Fluorescence spectroscopy may identify minute flaws in materials.
- Environmental Stress Cracking: Keeps an eye on how rubber breaks down and cracks in response to environmental stress.
Benefit:
sensitivity is high, and it can find minute concentrations of fluorescent materials.
selective, hardly affected by background noise and solely reacting to fluorescent materials.
The technique of near-infrared spectroscopy
The technology behind near-infrared spectroscopy principle:
The process known as near-infrared spectroscopy analyzes materials by using light in the near-infrared region, which is typically in the wavelength range of 780 to 2500 nanometers. The method can penetrate the sample and offer chemical and physical information since it is very sensitive to water and certain chemical bonding.
Utilization in the rubber testing process:
- Analyzes the chemical makeup of rubber, taking into account the kinds of polymers, fillers, and plasticizers.
- Rubber has a great sensitivity to water, making it possible to estimate its moisture level with accuracy.
- Process monitoring: Chemical changes during rubber manufacture are tracked online.
- Control quality by making sure rubber goods adhere to requirements.
