A multifaceted evaluation of plastics to determine any differences caused by the PC/ABS mixing process

A multifaceted evaluation of plastics to determine any differences caused by the PC/ABS mixing process

Fig. 1 View of Samples
The top sample was mixed in a mixing machine whereas the bottom sample was not

PC/ABS is a thermoplastic that combines the heat resistance, impact resistance, and flame resistance of PC plastics with the moldability and coating properties of ABS plastics. Due to their impact resistance, weather resistance, and moldability, PC/ABS plastics are widely used in automotive interior parts, office equipment, domestic electrical appliances, etc. However, because blended polymers such as PC/ABS may exhibit poor material properties depending on the mixing conditions, it’s important to examine the differences in properties due to the mixing conditions. An example is presented here.

Table 1 Heating Conditions before Molding

It was found that samples mixed in advance in a mixing machine were yellower and had smaller elongation at failure.
At the same time, no significant differences were found in tensile strength, elastic modulus, and hardness.

■ Measurement of Yellowness: UV-2600i

The samples mixed in a mixing machine had a higher degree of yellowness than those that were not.

Fig. 1 Results of UV Measurement

■ Tensile Testing: AGX-V

The elongation at failure of the samples mixed in a mixing machine was lower than for the samples that were not placed in a mixing machine. No significant differences were found in the tensile strength and elastic modulus.

Fig. 2 Tensile Test Results

Table 3 Tensile Test Results

■ Hardness Testing: DUH-210

The samples mixed in a mixing machine were slightly softer than those that were not placed in a mixing machine, but no significant differences were observed.

Since the possibility exists that the samples not mixed in a mixing machine were insufficiently mixed compared to the samples mixed in a mixing machine, thermal analysis by DSC and composition analysis by FTIR were performed at several locations to check the distribution of properties within the samples that had not been mixed in a mixing machine.
Neither thermal analysis nor compositional analysis showed any difference between measurement locations, confirming that the samples that had not been mixed in a mixing machine had been sufficiently mixed.

Even the samples that had not been mixed in a mixing machine were sufficiently mixed, so the distribution of material properties within the samples was virtually uniform. However, there were differences in the heating time at 260 °C before injection molding.
Because a heating temperature of 260 °C is high for ABS, it is believed that the yellowness and elongation at failure may have been affected by a change in butadiene, which, among the components of ABS, is said to be particularly sensitive to heat.