The solubility of CO2 in poly(ethylene terephthalate)(PET) was studied using magnetic suspension balance (MSB) combined with high-temperature high-pressure view cell.The former gives apparent solubility and the latter presents swelling volume through direct observation in the presence of CO2

which is necessary to correct the gas buoyancy acting on PET melts in the MSB measurement.The effects of temperature and pressure on the swelling ratio and CO2 solubility in traditional and modified PET melt were analyzed.The results show that both swelling ratio of PET and solubility of CO2 decrease as temperature increases and increase with pressure.However

the swelling ratio increases slowly and approaches a plateau region under higher pressure.Compared with traditional linear PET

the modified PET displays lower swelling ratio and solubility.Solubility of CO2 in PET melt is in an order of magnitude of 10-2 g CO2·(g PET melt)-1 under 4-6 MPa in the temperature range of 250-280℃.CO2 solubility in PET melt agrees well with Henry’s law in the pressure range of 1-6 MPa.Heat of solution is obtained using the least-square method.