Phenylvinyl silicone rubber is a special type of silicone rubber material. Its quality is primarily measured by key indicators such as volatile content, vinyl content, and phenyl content. The following are detailed testing methods and standards for these indicators:

I. Main Quality Indicators
1. Volatile Content
Volatile content refers to the amount of substances that volatilize from the raw rubber during heating, usually determined by the heating weight loss method. Excessive volatile content can lead to volume shrinkage of the vulcanized rubber, reducing mechanical strength and dielectric properties.

2. Vinyl Content
Vinyl content is a key indicator affecting vulcanization characteristics and is usually divided into five grades:
Ultra-low vinyl (0.03%-0.15%)
Low vinyl
Normal vinyl
High vinyl
Ultra-high vinyl
Too little vinyl content (less than 0.5%) does not significantly affect vulcanization, while excessive content will reduce the heat resistance of the vulcanized rubber.

3. Phenyl Content
Phenyl content directly affects the material's high and low-temperature resistance. The introduction of phenyl groups allows the silicone rubber to achieve low-temperature resistance down to -73°C while maintaining good heat resistance (long-term operation at 180°C).

II. Testing Methods and Standards
1. Volatile Content Testing
The heating weight loss method is used, and the mass loss of the sample during heating is measured using a thermogravimetric analyzer (TGA). 2. Vinyl Content Detection
There are two main methods:
Nuclear Magnetic Resonance Hydrogen Spectroscopy (FT-NMR): Using a 400 MHz or higher frequency nuclear magnetic resonance spectrometer, the content is calculated by measuring the chemical shift and peak area of the vinyl hydrogen.
Bromine Iodide Titration Method: The content is determined by titrating with a sodium thiosulfate standard solution after the reaction of bromine iodide solution with the vinyl group.

3. Phenyl Content Detection
The main method is Nuclear Magnetic Resonance Hydrogen Spectroscopy (FT-NMR):
Using deuterated tetrahydrofuran (C4D8O) as the solvent.
Measuring the chemical shift (6.5-8 ppm) and peak area of the phenyl ring hydrogen.
Repeatability requirement: r ≤ 0.05; Reproducibility requirement: R ≤ 0.1

III. Detection Equipment
Nuclear Magnetic Resonance Spectrometer (FT-NMR): 400 MHz or higher frequency, used for vinyl and phenyl content determination.
Thermogravimetric Analyzer (TGA): Used for volatile matter detection.
Electronic Balance: Accuracy 0.1 mg, used for sample weighing.

IV. Impact of Indicators on Performance
Indicator | Impact
Volatile matter | Affects the mechanical strength and dielectric properties of vulcanized rubber.
Vinyl content | Affects vulcanization characteristics and heat resistance.
Phenyl content | Affects high and low temperature resistance.
By controlling these key indicators, it can be ensured that the phenyl vinyl raw rubber meets the performance requirements of different application scenarios. In actual testing, it is recommended to use nuclear magnetic resonance hydrogen spectroscopy as the main detection method due to its high accuracy and good repeatability.