Online pressure-volume-temperature measurements of polypropylene using a testing mold to simulate the injection-molding process

• Published in: Journal of applied polymer science Vol. 118; no. 1; pp. 200 - 208
• Main Authors: Wang, Jian, Xie, Pengcheng, Yang, Weimin, Ding, Yumei
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 05.10.2010; Wiley
• Subjects: Applied sciences; Exact sciences and technology; Heating; Injection molding; Injection moulding; Machinery and processing; melt; molding; Molds; Moulding; On-line systems; Online; Plastics; Polymer industry, paints, wood; Polypropylenes; Reproduction; Service life; simulations; Technology of polymers; PVT diagram; On line; Warping; Propylene polymer; Processability; Semicrystalline polymer; Shrinkage; Experimental study; Property processing relationship; Modeling; simulations; Equations of state; melt; Injection molding; Olefin polymer; Numerical simulation; Technological properties; molding; Measurement method; Mold filling; Thermodynamic properties
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.32070

To obtain accurate prediction of service performance and service life of polymers and to optimize the processing parameters, a modified online measurement was used to measure the pressure-volume-temperature (PVT) properties of polymers under certain processing conditions. The measurement was based on an injection molding machine, and it was used to obtain the PVT data of polymers directly with a special testing mold under normal processing conditions. The PVT properties of a semicrystalline polymer, polypropylene, were measured through both an online testing mold and a conventional piston-die dilatometer. The PVT properties were correlated by a modified two-domain Tait equation of state. The differences between the two groups of PVT data measured were investigated, and relative differences, especially in the rubbery state because of different cooling or heating measuring modes and sample forms, were observed. Numerical simulations of injection-molding processes were carried out by Moldflow software with both of the types of PVT data. The resulting online PVT data exhibited improvement in the accurate prediction of shrinkage and warpage.