화학공학소재연구정보센터
International Polymer Processing, Vol.24, No.2, 114-121, 2009
A Novel Dilatometer for PVT Measurements of Polymers at High Cooling -and Shear Rates
A novel dilatometer to investigate the specific volume of polymers as a function of the combined effect of pressure (100 MPa), temperature (300 degrees C), cooling rate (100 degrees C/s) and shear rate (200 l/s) was developed. The dilatometer consists of a pressure cell, which in design, is a combination of a traditional "piston-die type" dilatometer and a Couette rheometer, embedded in a custom made frame, which allowed for scaling down to a "table-sized" machine that requires only standard laboratory supplies, like pressurized air and tap water, for operation and cooling. We implemented soft-ware for fully automated control of procedures to operate non-isothermal experiments with shear steps applied at predefined temperatures. The sample rings (m approximate to 65 mg) used in the dilatometer are made with a micro injection moulding machine. Experiments with two commercial isotactic Polypropylene (iPP) grades at low cooling rates, performed by two independent groups, were compared with measurements from a commercial confined fluids dilatometer showing small relative differences in the range of 0.03 to 0.3%. As an example, additional results of an isotactic polypropylene were chosen to show the profound influence of cooling rate and melt shearing on the evolution of specific volume.