B. Differential Scanning Calorimetry Technique, DSC

Principle

DSC, as a thermal analysis method that can measure many thermodynamic and kinetic parameters, can see the changes in polymerization structure caused by molecular motion at different temperatures. Measure the power difference (e.g. in the form of heat) between the input sample and the reference sample at the programmed temperature. The curve recorded by the differential scanning calorimeter is called DSC curve. It takes the heat absorption rate of heat release rate of the sample, that is, the heat flow rate dH/dt (unit millijoule/second) as the ordinate and the temperature T or time T as the abscissa, and then makes a thermal image.

Experimental procedure [13]:

Start up and preheat, and add nitrogen protective gas.
Take a 10mg sample, weigh it, crush or cut the sample, put the sample flat into a small crucible with tweezers, the sample does not exceed 1/3 volume, then cover the crucible lid and seal it with pressure secret, and then poke a small hole on the lid.
Put the sample crucible and blank control crucible into the instrument.
Set parameters: termination temperature 200 degrees, heating rate 10 degrees per minute.
Save and export the data. Take out the sample.
Turn off the instrument and computer immediately after the experiment.
Map

Spectrum analysis:

Line ① represents the glass transition temperature. It can be seen that the glass transition temperature of PLA plus is about 55℃.

Line ② represents crystallization. It can be seen that the crystallization temperature of PLA plus is about 110 ℃.

Line ③④ represents melting. It can be observed that the melting peak of the sample shows two peaks at 145℃ and 155℃. Compared with the DSC image of pure PLA^[1], it is found that the melting peak of PLA is separated into two separate peaks by the addition of PBAT.

The data are basically consistent with those in the literature, and the results are reliable.

Figure.5 DSC of PLA/PBAT

Data declaration

PLA Plus has a high glass transition temperature, which results in difficulty in machining, so it needs to mix other materials to facilitate machining. For this experiment, the material we chose is PLA Plus with 20% PBAT added.

Characteriaztion

Confirm copying