1
|
Tao K, Yamada K, Higashi S, Kago K, Kuwashiro S, Hirano H, Takeshita H, Tokumitsu K. Effect of molding history on molecular orientation relaxation during physical aging of polystyrene injection moldings. INT POLYM PROC 2023. [DOI: 10.1515/ipp-2022-4264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Abstract
This work examined the effect of changing molding conditions on the physical aging of polystyrene injection moldings. First, we investigated the relationship between the molecular orientation and the molding conditions. The molecular orientation near the surface changed with changing injection rate, so we hypothesized that this molecular orientation might form during the filling stage. Because this molecular orientation did not relax under heat treatment below the glass transition temperature (T
g), the oriented molecules near the surface were thought to be elongated owing to the high strain rate during the filling stage. On the other hand, the molecular orientation in the core layer changed with changing holding pressure and relaxed under heat treatment below T
g. Thus, the molecules in the core layer might become oriented during the holding stage and not be elongated owing to the slow strain rate. Furthermore, the molecular orientation in the core layer decreased with increasing mold temperature, and the physical heat resistance improved with increasing mold temperature. Meanwhile, the excess enthalpy did not change with changing molding conditions. Therefore, the improvement in physical heat resistance with increasing mold temperature was likely caused by the decrease in the molecular orientation in the core layer. Analyzing the relaxation behavior of the molecular orientation suggested that increasing mold temperature reduced the number of oriented molecules with large deformation in the core layer.
Collapse
Affiliation(s)
- Kousaku Tao
- Osaka Research Institute of Industrial Science and Technology , Osaka-city , Japan
- Department of Material Science , School of Engineering, University of Shiga Prefecture , Hikone-city , Japan
| | - Koji Yamada
- Osaka Research Institute of Industrial Science and Technology , Osaka-city , Japan
| | - Seiji Higashi
- Osaka Research Institute of Industrial Science and Technology , Osaka-city , Japan
| | - Keitaro Kago
- Osaka Research Institute of Industrial Science and Technology , Osaka-city , Japan
| | - Shiho Kuwashiro
- Osaka Research Institute of Industrial Science and Technology , Osaka-city , Japan
| | - Hiroshi Hirano
- Osaka Research Institute of Industrial Science and Technology , Osaka-city , Japan
| | - Hiroki Takeshita
- Department of Material Science , School of Engineering, University of Shiga Prefecture , Hikone-city , Japan
| | - Katsuhisa Tokumitsu
- Department of Material Science , School of Engineering, University of Shiga Prefecture , Hikone-city , Japan
| |
Collapse
|
2
|
Healy J, Knott R, Edward G. Residual orientation in injection-moulded plaques of atactic-polystyrene I: The effect of processing conditions. POLYM ENG SCI 2018. [DOI: 10.1002/pen.24710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- John Healy
- Materials Science and Engineering, Faculty of Engineering; Monash University; Victoria 3800 Australia
| | - Robert Knott
- Australian Nuclear Science and Technology Organisation; Kirrawee NSW 2232 Australia
| | - Graham Edward
- Materials Science and Engineering, Faculty of Engineering; Monash University; Victoria 3800 Australia
| |
Collapse
|
3
|
|
4
|
Viana JC, Alves NM, Mano JF. Morphology and mechanical properties of injection molded poly(ethylene terephthalate). POLYM ENG SCI 2004. [DOI: 10.1002/pen.20245] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|