Comprehensive PVDF Powder Buying Guide

30 5 月, 2024
6:08 上午

PVDF is the second most commonly used product in the fluoroplastic series. Due to its excellent processing performance, PVDF has seen rapid development in recent years. PVDF anti-corrosion products can be used as linings for valves and pipelines, and can also be made into fully plastic parts. PVDF products are also widely used as lithium battery binders, water treatment membranes, coatings, solar PV backsheets, etc.

Due to its popularity and wide application in various industries, there are many PVDF power or resin products on the market. Choosing among multiple products and manufacturers would be a challenge for buyers.

This guide aims to provide a comprehensive guide to help those buyers make suitable decisions when purchasing PVDF powder.

What Is PVDF?

First of all, we are gonna start with a detailed introduction for PVDF powder to help you better understand the properties of this product.

Polyvinylidene fluoride, abbreviated as PVDF, is a highly non-reactive thermoplastic fluoropolymer. It is synthesized through the polymerization of 1,1-difluoroethylene. PVDF is soluble in strongly polar solvents such as dimethylacetamide. It exhibits excellent properties including aging resistance, chemical resistance, weather resistance, and UV radiation resistance.

Properties of PVDF

PVDF is a crystalline polymer known for its low melting point, high mechanical strength, abrasion resistance, cut resistance, high temperature resistance, corrosion resistance, and high dielectric constant. Beyond these qualities, PVDF exhibits excellent weather resistance, UV resistance, radiation resistance, and processing properties. Moreover, PVDF has a low processing temperature and good melt flowability. It also possesses good gas barrier properties, unique piezoelectric properties, thermoelectric properties, and more.

Physical Properties

PVDF powder or granule is translucent or white, with tightly arranged molecular chains and strong hydrogen bonds. It’s non-flammable and has following physical properties:

Oxygen Index: 46%
Crystallinity: 65% to 78%
Density: 1.17 to 1.79 g/cm3
Melting Point: 172°C
Heat Deformation Temperature: 112 to 145°C
Long-Term Use Temperature: -40 to 150°C

PVDF is mainly used in applications where purity is extremely high and resistance to solvents and acid and alkali corrosion is required. Compared to other fluorinated polymers, such as polytetrafluoroethylene, PVDF has a lower density (1.78 g/cm³), which helps improve its mechanical strength and durability.

Mechanical Properties

With a tensile strength typically ranging from 40 to 50 MPa, PVDF powder has the resilience against stretching or pulling forces. Its elongation at break spans from 20% to 300%, showing its remarkable flexibility and capacity for significant deformation prior to fracturing. Additionally, its flexural modulus, ranging from 1.4 to 2.5 GPa, signifies stiffness during bending.

With high impact resistance, PVDF effectively absorbs and dissipates energy upon impact without succumbing to breakage. Furthermore, it demonstrates notable compressive strength, fatigue resistance, creep resistance, and abrasion resistance, ensuring durability and reliability in various load-bearing and wear-prone applications.

Thermal Properties

Melting Point: Around 177°C (351°F), indicating the temperature at which PVDF transitions from solid to liquid.
Glass Transition Temperature: Approximately -35°C (-31°F), below which PVDF becomes more brittle and glass-like.
Thermal Conductivity: Low, about 0.19 W/m·K, making PVDF a good thermal insulator.
Thermal Stability: Retains its properties over a wide temperature range, suitable for both high and low-temperature applications.
Heat Deflection Temperature: The temperature at which PVDF begins to deform under a specified load, typically around 110°C (230°F).

Electrical Properties

In order to impart piezoelectric properties to PVDF material, it is usually first mechanically stretched along the direction of the molecular chains, and then polarized under tension. PVDF has several solid phases: α phase (TGTG’), β phase (TTTT), and γ phase (TTTGTTTG’). The difference between these phases lies in whether the molecular chains are in trans (T) or gauche (G) conformations.

After polarization, PVDF becomes a ferroelectric polymer, exhibiting excellent piezoelectricity and pyroelectricity. When PVDF exhibits piezoelectric behavior, it can generates an electric charge in response to mechanical stress, and can respond to electrical stimuli. These properties make it suitable for producing sensors and batteries, such as the sensors used in some new types of thermal imaging cameras that utilize PVDF films.

Unlike some other piezoelectric materials like PZT, PVDF has a negative d33 value. From a physical perspective, this means that while other materials expand in an electric field, PVDF contracts, and vice versa.

Factors to Consider When Buying PVDF Powder

When purchasing PVDF powder for various applications, several factors should be considered to ensure optimal performance and suitability for specific requirements. The data and performance that should be paid attention to when selecting PVDF powder for different applications are also different. We have given examples in the corresponding paragraphs below.

1. Purity and Quality

High purity PVDF is crucial for applications requiring minimal contamination and consistent performance. For example, in the pharmaceutical industry, PVDF used for producing drug delivery systems or medical implants must meet stringent purity standards to ensure safety and efficacy.

2. Particle Size and Distribution

The particle size and distribution of PVDF powder affect its flow properties, dispersion, and final product characteristics. In coatings and adhesives applications, finer particle sizes may lead to smoother surfaces and better film formation, while larger particles may enhance mechanical properties in composites.

3. Molecular Weight

The molecular weight of PVDF influences its mechanical properties, processability, and end-use performance. For instance, in membrane and filtration applications, PVDF with higher molecular weight may offer improved mechanical strength and durability, leading to longer service life and higher efficiency.

4. Thermal Properties

Consideration of PVDF’s thermal stability and heat resistance is essential for applications exposed to elevated temperatures. For example, in electrical insulation or aerospace applications, PVDF powder with a high melting point and low thermal expansion coefficient is preferred to ensure reliability and performance under harsh thermal conditions.

5. Chemical Compatibility

PVDF’s resistance to various chemicals is critical for applications in aggressive environments. In chemical processing or automotive industries, PVDF powder should be chosen based on its compatibility with specific chemicals, fuels, or solvents to prevent degradation or corrosion of components.

6. Electrical Properties

PVDF’s dielectric properties are essential for electrical and electronic applications. For example, in cable insulation or capacitor manufacturing, PVDF powder with high dielectric strength and low dissipation factor is desirable to ensure efficient electrical performance and reliability.

7. Application-Specific Requirements

Consideration of unique application requirements is paramount. For instance, in 3D printing or additive manufacturing, PVDF powder with tailored rheological properties and flow characteristics is needed to achieve precise printing results and dimensional stability.

8. Regulatory Compliance

Ensure that the PVDF powder meets relevant industry standards and regulatory requirements. For example, in food contact materials or medical devices, PVDF powder should comply with FDA regulations or medical device directives to ensure product safety and compliance.

Types and Grades of PVDF Powder

PVDF (polyvinylidene fluoride) powder is available in various types and grades, each tailored for specific applications and properties. Here are the main types of PVDF powder based on the provided sources:

Standard Homopolymer PVDF

This is the basic form of PVDF, known for its high dielectric constant, chemical resistance, and thermal stability. It is used in applications such as high energy density capacitors, ferroelectric, piezoelectric, and pyroelectric technologies, as well as lithium-ion battery binders.

Copolymer PVDF

PVDF-HFP (Hexafluoropropylene): This copolymer has improved flexibility and processability compared to the homopolymer. It is used in applications like high energy density film capacitors, soft actuators for robotics, and lithium-ion battery binders.
PVDF-CTFE (Chlorotrifluoroethylene): Known for its excellent low-temperature performance and low shrinkage, it is ideal for wire and cable applications.
PVDF-TFE (Tetrafluoroethylene): This copolymer improves the piezoelectric response by enhancing the crystallinity of the material.

Conductive PVDF

This type includes PVDF modified with conductive fillers such as carbon black or silver nanoparticles. It is used for applications requiring electrical conductivity, such as electrostatic dissipative parts and wearable electronic devices.

Reinforced PVDF

This type includes PVDF powder reinforced with materials like glass fibers or carbon fibers to enhance mechanical properties. It is used in highly demanding applications like compression molding and highly reinforced composites.

Suppliers and Manufacturers

When choosing PVDF powder, choose to buy it from well-known brands or manufacturers if you are concerned about product quality and don’t know how to choose. We have write an article about “best 8 PVDF manufacturer worldwide in 2024“, hope it can do you a favour!

Except looking for reputable manufacturers to ensure product quality, you can also attatch great importance to certifications and standards. Certifications such as ISO and other industry standards can guarantee manufacturers’ adherence to quality and safety benchmarks. By ensuring compliance with industry standards like ASTM and ISO, you can make sure the supplier meets the requisite criteria for quality assurance and safety protocols, thereby instilling confidence in the product’s reliability and performance.

Testing and Quality Assurance

When choosing a PVDF powder, you can request a sample from the manufacturer for thorough quality testing to ensure it is suitable for its intended use. Firstly, assess the powder’s physical properties, including particle size distribution, morphology, and flow characteristics, through techniques like laser diffraction, scanning electron microscopy (SEM), and flowability tests.

Additionally, verify the powder’s chemical composition and purity using methods such as Fourier-transform infrared spectroscopy (FTIR) or nuclear magnetic resonance (NMR) spectroscopy to confirm the absence of impurities that may affect performance.

Furthermore, evaluate the powder’s thermal properties, such as melting point and heat stability, through differential scanning calorimetry (DSC) or thermogravimetric analysis (TGA). Lastly, assess the powder’s mechanical properties, including tensile strength, elongation at break, and impact resistance, through mechanical testing methods to ensure it meets the required specifications for the application.

By conducting comprehensive quality testing, you can confidently select PVDF powder that meets their performance, reliability, and safety standards.

Conclusion

When buying PVDF powder, it’s crucial to consider factors like purity, particle size, molecular weight, and thermal properties. Select reputable suppliers who provide high-quality products and ensure compliance with industry standards. By understanding these aspects and taking a thorough approach to testing and quality assurance, buyers can make informed decisions that best meet their needs.

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