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Abstract
Shear viscosity of the cyclic olefin copolymer (COC) plasticized by ultrasonic vibration energy is characterized by high pressure capillary rheometer. Two different plasticization modes were adopted to prepare the samples with an in-house developed prototype machine. Single-factor experiments were conducted to investigate the effects of ultrasonic energy on the shear viscosity. The influences of the processing parameters and the plasticization modes were analyzed and compared. The results showed that the shear viscosity of COC was reduced under various parameter combinations, and demonstrated a significant difference in the lower shear rate range in comparison with the control samples; the results of gel permeation chromatography (GPC) showed that the COC’s number average molecular weight () was decreased and the polymer dispersity index (PDI) was increased due to the plasticization by ultrasonic vibration energy. This could be further account for the decrease of the shear viscosity of COC. Moreover, the predominant ultrasonic parameter changed in different modes of plasticization according to the statistical analysis based on the Statistical Product and Service Solutions (SPSS) software.
Highlights
Microinjection molding has been successfully and widely applied in the fabrication of polymeric micro parts [1], such as micro heat exchangers, bio-medical chips and miniaturized optical devices [2], due to its intrinsic advantages in cost saving and efficiency increasing
Following the accomplishment of rheology experiment, relevant data needed for multiple linear regression analysis (MLRA) are selected
As to statistical results of Mode 1, it is clear that the standardized coefficient β of ultrasonic action time is of the biggest absolute value according to Table 8, which means that ultrasonic action time is the most powerful, which is in line with the experimental data
Summary
Microinjection molding has been successfully and widely applied in the fabrication of polymeric micro parts [1], such as micro heat exchangers, bio-medical chips and miniaturized optical devices [2], due to its intrinsic advantages in cost saving and efficiency increasing. One of them is that higher levels of process parameters such as injection pressure and melt temperature are usually essential for an improved molding quality. This is quite energy-consuming because a large part of the energy is used to maintain the melt temperature and to drive the injection unit. Another disadvantage lies in the extremely low utilization ratio of the polymer melt. Due to the size effects existing in the filling process of micro-cavities, the filling process of microinjection molding is rendered extremely complicated
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