YY/T 1707-2020Implants for surgery—Differential scanning calorimetry of poly ether ether ketone (PEEK)polymers and compounds for use in implantable medical devices (English PDF)

3.1 Glass transition

The amorphous regions in amorphous polymers or semi-crystalline polymers change from (or to) viscous fluid state, rubbery state to (or from) hard, relatively brittle glass A reversible change in the glass state is shown by a step change in heat flow during heating.

3.2 Extrapolated onset temperature of glass transition

The temperature corresponding to the intersection of the tangent at the inflection point of the curve is extrapolated from the initial baseline on the low temperature side of the curve.

3.3 Midpoint temperature of glass transition

The temperature corresponding to the intersection point of a line with the same distance from the two extrapolated baselines and the curve.

3.4 Melting temperature

The temperature at which a fully crystalline or semi-crystalline polymer changes from a solid state to a liquid state with different viscosities is shown as an endothermic curve in the DSC curve The peak temperature. see picture 1.

Note. The DSC curve does not include transitions other than those listed in Table 1.

Figure 1 Typical DSC curve of PEEK heating curve

3.5 Crystallization temperature

The temperature at which the amorphous liquid state of the polymer transforms to a completely crystalline or semi-crystalline solid state, which is expressed in the differential scanning calorimetry (DSC) curve Is the peak temperature of the exothermic peak.

4.1 Differential Scanning Calorimeter (DSC)

The main features of the instrument should meet the requirements of GB/T 19466.1.

4.2 Sample crucible

The sample crucible and the reference crucible required for the test material should be made of the same material and have the same size and quality. Material of the sample crucible The material should be physically and chemically inert relative to PEEK within 500°C. Example. aluminum.

4.3 Balance

The balance should be able to measure the mass of samples, sample crucibles and reference crucibles with an accuracy of ±0.01 mg.

4.4 Reference materials At least two certified

reference materials covering the temperature range to be measured are required.

4.5 Air source

Inert gas should be used (for example. nitrogen with a purity of 99.99% or higher).

6.1 Test conditions

The test should be performed under laboratory environmental conditions. The DSC should be turned on at least 1h before the start of the test in order to balance the electronic components and temperature.

6.2 Sample status adjustment

The sample should be adjusted at a constant temperature of 18°C~28°C for at least 4h.

7.1 Temperature calibration

Measure the transition temperature of two standard materials and measure the extrapolated starting temperature of the glass transition according to GB/T 19466.1. Nominal value Compare with actual measured value. The temperature calibration repeatability should not exceed 2%.

7.2 Energy calibration

Determine the heat of fusion of the two standard materials and compare these values with the nominal values. Repeatability should not exceed 2%.

8.1 Baseline measurement

Place two empty sample crucibles with the same mass on the sample holder. Adjust to the actual measurement conditions. On request Within the temperature range, the DSC curve (ie the instrument baseline) should be close to a straight line. If a significant baseline curvature change is observed, check the sample support Whether the holder is contaminated.

Note. The computer-controlled instrument can be used to correct the excess curvature changes by subtracting the instrument baseline from the DSC curve.

When the ideal straight line cannot be obtained, record the DSC curve after confirming its repeatability.

8.2 Sample preparation

At least two samples should be prepared for each batch or sample to be checked. Follow the steps below, and the following weighing is accurate to 0.1mg.

---Weigh and record the quality of the sample crucible and lid;

---Put the PEEK sample into the sample crucible. Adjust the sample quality to be between 5mg~15mg, and record the sample quality;

--- Use the lid to seal the sample crucible according to the steps recommended by the manufacturer;

---Weigh the sealed sample crucible again and record the quality;

--- Weigh and record the quality of the reference crucible. Use the lid to seal the reference crucible according to the procedure recommended by the manufacturer;

---Weigh the sealed reference crucible again and record the mass.

8.3 Place the sample crucible

Use appropriate equipment (such as tweezers) to put the sample and reference crucible into the corresponding DSC furnace. Ensure that the bottom of the crucible and the heating furnace Good, close contact between. Close the instrument cover.

8.4 Temperature scan program

The following temperature program should be used.

a) Heat the sample from 30°C to 400°C at a heating rate of 20°C/min;

b) Maintain a constant temperature at 400°C for 5 minutes;

c) Cooling from 400°C to 30°C at a cooling rate of 20°C/min;

d) Reheat from 30°C to 400°C at a heating rate of 20°C/min.

8.5 Sample inspection

Remove the sample crucible from the instrument and check whether the crucible is overflowing or deformed. If overflow or deformation occurs, separate the crucible and lid, and observe Check the remaining sample for signs of volatilization or reaction.

Due to the stability of the PEEK and PEEK compound, there should be no sample crucible overflow and/or deformation.

If any signs of volatilization or reaction are observed in a batch of PEEK or PEEK compound, the test result should be discarded.

8.6 Data analysis

8.6.1 General

The data should be processed according to the instrument manufacturer's instructions.

8.6.2 Melting temperature

The melting temperature Tm shall be determined and recorded according to GB/T 19466.3.

8.6.3 Crystallization temperature

The crystallization temperature Tc during the cooling process shall be determined and recorded in accordance with GB/T 19466.3.

8.6.4 Glass transition temperature

The glass transition temperature should be measured from the second heating cycle according to GB/T 19466.2. Record vitrification in Teig or Tmg Transition temperature Tg.