Explore KF PVDF

Kureha's KF Polymer Line-Up & Properties

Explore KF PVDF

KF Polymer is the trade name for PVDF produced exclusively by the Kureha Corporation since 1970. Since its introduction, KF PVDF has become recognized world-wide as a versatile engineering fluoropolymer thermoplastic with excellent properties and performance. Its unique combination of properties make it the material of choice for applications requiring easy processing, which makes it similar to those of conventional polymers.

Products made with KF PVDF exhibit superior retention of thermomechanical properties when exposed to heat or chemicals with strong acids and weak bases. Its unique combination of properties makes it ideal for applications requiring straightforward processing techniques such as extrusion, molding and thermal welding.

KF Polymer Line-Up and Properties

Mechanical Properties

The glass transition temperature of KF Polymer is about -35°C, and its crystallinity is high. It shows good mechanical properties compared to other fluoropolymers. Crystallization speed is high (see thermal properties on p.8), and dimensional stability of mold can be improved by annealing at 80-150°C.

Tensile Properties (ISO537-2)

Tensile Strength (KF 1000)

Tensile strength decreases as temperature increases. Even at 100°C, tensile strength is about 35MPa or more.

Tensile Creep (ASTM D2990, 10MPa)

Tensile Creep - Elongation (KF 1000)

PVDF exhibits fine creep resistance, unlike other fluoropolymers that typically show large tensile creep.

Tensile Creep (ISO899-1 23°C, 8MPa)

Flexural Creep (ISO899-2 23°C, 8MPa)

Melt Viscosity (Shear Rate=100sec-1)

Izod Impact Strength (ASTM D256 - Notched)

Dynamic Viscoelasticity (Heating Rate: 2°C /min, 10Hz)

Viscoelasticity (KF 1000)

The peak which indicates glass transition appears at -35°C. Exceeding the glass transition temperature, elastic modulus (E') gradually decreases.

Thermal Properties

KF Polymer (homopolymer) has a glass transition temperature (Tg) at -35°C measured by the DMA (dynamic mechanical analysis). KF Polymer without any additives has flame retardance meeting UL94V-0 or equivalent and LOI (limiting oxygen index) value of 44.

Melting & Crystallization Points

Thermal Decomposition

Melting Point & Crystallization Point

(DSC, ASTM D3418)

The behavior of melting point and crystallization point (KF 1000)

Heating or cooling rate: 10°C /min in N2 The melting point of KF Polymer (homopolymer grade) is 175°C. The crystallization point is 145°C. Since crystallization rate is rapid, cold crystallization is not usually observed. The melting point of copolymer grade is slightly lower than that of homopolymer grade.

Thermal Decomposition

(TGA, ISO 11358)

Thermogravimetric analysis (KF 1000)

Heating rate: 10°C /min in N2 The decomposition begins at about 360°C. However, if KF Polymer is held at elevated temperature for an extended time, thermal decomposition can occur below 360°C. At the time of processing, PVDF should not be left over 280°C for a long periods.

Electrical Properties

Since KF Polymer has a very large dipole moment, the dielectric constant is very high. A measured value is around 10 for non-oriented material. In general, dielectrics which have high dielectric constant show low volume resistivity, but KF Polymer maintains high insulation. Similarly, dielectric breakdown strength is high, but dissipation loss (about 0.013) is comparatively large.

Frequency Dispersion (ASTM D150)

The loss tends to be large in the region of high frequency. Temperature Dispersion (Heating rate: 2°C /min) The glass transition temperature measured by dielectric constant is -35°C as well as dynamic viscoelasticity. The dielectric constant is about 3 in glass state, where molecular motion is restricted. When the molecular motion is free, the dielectric constant is very high. The peak which is regarded as crystalline dispersion exists around 80°C.

Dielectric Constant Frequency Dispersion (KF 1000) at 23°C

Dielectric Constant (KF 1000)

tanδ (KF 1000)

Thermal Decomposition

(TGA, ISO 11358)

Thermogravimetric analysis (KF 1000)

Heating rate: 10°C /min in N2 The decomposition begins at about 360°C. However, if KF Polymer is held at elevated temperature for an extended time, thermal decomposition can occur below 360°C. At the time of processing, PVDF should not be left over 280°C for a long periods.

Chemical Properties

Since KF Polymer has strong polarity, it may be attacked by some polar solvents. Even if significant discoloration is caused by alkali and amine compounds, remarkable deterioration of mechanical properties are not seen. KF Polymer has good resistance to acids. However, it can be attacked by certain strong acids (fuming sulfuric acid, fuming nitric acid). KF Polymer can be used in contact with hydrocarbons, organic acids, alcohols, and chloro-hydrocarbons, but it may swell or partially dissolve in basic amines, highly polar esters, ketones, ethers and amides. Examples of polar solvents dissolving KF Polymer are NMP (N-Methyl-2-pyrrolidone), DMF (Dimethyl formamide), DMA (Dimethyl acetamide) and DMSO (Dimethyl sulfoxide).

Evaluation Method & Criteria

Sample; KF Polymer sheet 50mm×50mm×2mm
Immersion Time; over 1000 hours until weight increase is saturated
Criteria Value of Weight Gain; 3.0mg/cm2 for inorganic chemicals, 7.0mg/cm2 for organic chemicals

1) No appearance change

The weight gain reaches saturation below the criteria value without any appearance change.

2) Appearance slightly changes but still usable

The weight gain reaches saturation slightly below the criteria value with little change.

3) Needs special attention for use

The weight gain reaches saturation above the criteria value, with some appearance change.

4) Appearance severely changes and not recommended for use

The weight gain does not reach saturation with dissolution or crack /craze.

(Note) Appearance changes include crack and craze without color change.

KF Polymer Chemical Resistance Table

Tensile Elongation of KF Polymer after Ozone Exposure

Ozone resistance properties of KF Polymer are very good compared with High Density Polyethylene (HDPE). Exposure conditions:

  • 1.0-1.2% Ozone
  • Room temperature
  • Sample thickness=0.15mm
  • Sample width=5mm
  • Testing length=20mm
  • Tensile speed=1.0mm/min.

Ozone Resistance Properties (KF 1000)

Thermal Decomposition

(TGA, ISO 11358)

Thermogravimetric analysis (KF 1000)

Heating rate: 10°C /min in N2 The decomposition begins at about 360°C. However, if KF Polymer is held at elevated temperature for an extended time, thermal decomposition can occur below 360°C. At the time of processing, PVDF should not be left over 280°C for a long periods.

Purity

Elution of Impurities

Content of Trace Materials

Purity - Elution of Impurities

KF Polymer is inherently pure and applied to parts for ultrapure water piping system.

Elution of total organic carbon (TOC) (95°C hot water, 6 days)

Purity - Content of Trace Materials

KF Polymer contains very low level of metals.

Content of trace metals of KF Polymer (Neutron Activation Analysis) (KF 1000)

Permeation

Water Vapor Transmission

Gas Barrier Properties

Permeation - Water Vapor Transmission

Water Vapor Transmission Rate (WVTR) of KF Polymer (ISO 15106-2)

(Film thickness: 20μm, 40°C 90%RH)WVTR of KF Polymer is very low compared with other polymers.

Permeation - Gas Barrier Properties of KF Polymer

O2 and CO2 permeability of KF Polymer and other polymers)

(Film thickness: 20μm, 30°C, 80%RH) Gas Barrier properties (oxygen, carbon dioxide) of KF Polymer are superior to those of other commodity thermoplastics, and bear comparison with other engineering plastics.

Optical Properties

Ultraviolet - Visible Spectrum of KF Polymer

(KF 1000, Film thickness: 100μm)

Ultraviolet and Visible transmission

As a film (thickness=100μm), visible light transmittance (parallel light transmission) is about 60%. It is possible to increase light transmittance by thinning film (2-axis ex tension film, etc.). Thick parts such as molded items have an opaque white appearance due to optical dispersion by fine crystals.

Weathering

Mechanical Properties

Optical Properties

Weathering - Mechanical Properties

Weatherability - Mechanical Properties

KF polymer has excellent weatherability. Therefore, it has been used as a transparent antifouling film material for the outdoors. Weatherability Test - Mechanical Properties:

  • Exposure Condition: Weatherometer, Carbon-arc lamps
  • Cycle: 12min spray / 60min stop, 63±3°C, 50-60%RH
  • Sample: KF 1000
  • Film thickness: 35μm

Weathering - Optical Properties

Weatherability - Optical Properties

The optical properties of KF Polymer are affected only by outdoor exposure slightly. KF Polymer is used as various kinds of cover films. Weatherability Test - Optical Properties:

  • Exposure Condition: Super UV tester, Fluorescent UV lamps, 0.83W/cm2
  • Black Panel Temp.: 63°C, 60%RH
  • Sample: KF 1000
  • Film Thickness: 100μm