The effects of vibration field on crystal structures and orientation of isotactic polypropylene injection samples

Zhang, Jie; Liu, Hong; Zhang, Lei; Zhou, Qixiong; Gao, Xueqin; Shen, Kaizhi

doi:10.1007/s00289-011-0627-4

Cited by 8 publications

(2 citation statements)

References 30 publications

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“…Ultrasonic oscillation techniques are typically used in polymer processing to solve the problems associated with the viscosity of polymer melts. Ultrasonic vibrations have been applied in a low-frequency range to injection molding screws [1,2] and mold sprues [3], and studies have analyzed the effects of shearing on orientation, crystallization and mechanical properties [4,5]. Ultrasonic vibration has also been applied to the extrusion of composites [6,7], and an ultrasonic measuring technique was used in the injection molding of thermoplastics [8].…”

Section: Introductionmentioning

confidence: 99%

Characteristics analysis and mold design for ultrasonic-assisted injection molding

Yang

Huang

Lin

et al. 2014

Journal of Polymer Engineering

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This study investigated the use of ultrasonic technology in assisted injection molding (AIM) and mold design. An ultrasonic device installed in a mold was employed to vibrate a melt, thereby converting kinetic energy into thermal energy. This method enabled maintaining the desired temperature in the melt flow, preventing a high level of shear and the formation of a thick frozen layer surrounding the skin layer; thus, the injection molding efficiency was enhanced and the residual stress inside the injection-molded component was reduced. In this study, a flat sample (75 mm × 47 mm × 1 mm) of an ultrasonic-assisted injection mold was developed. An ultrasonic oscillation device 45 mm in diameter was placed in the center of the cavity and used to vibrate a polycarbonate melt at a frequency of 20 KHz. In addition, cavity pressure sensors were positioned at the front and rear of the vibration region to analyze the melt flow behavior under ultrasonic-AIM (UAIM) conditions. The results showed that ultrasonic oscillations can reduce the amount of melt pressure lost through the cavity. The pressure loss of the flat sample used in UAIM was approximately 29% lower than that of the sample used in conventional injection molding (CIM; nonultrasonic-assisted injection); the power of UAIM did not yield substantial effects. Direct ultrasonic oscillations destroyed the melt flow and thermal stresses, therefore, the region exhibited a low stress distribution. Compared with using CIM, using UAIM reduced the average residual stress by 27%. Ultrasonic oscillation affected the surface roughness during melt solidification. When the ultrasonic power was < 70%, no substantial increase in surface roughness was observed; however, when the ultrasonic power > 70%, the surface roughness was 10 times higher compared with that observed using CIM.

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Section: Introductionmentioning

confidence: 99%

Characteristics analysis and mold design for ultrasonic-assisted injection molding

Yang

Huang

Lin

et al. 2014

Journal of Polymer Engineering

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“…Qu 1 and Wang and Qu 2 mainly researched the influence of the electromagnetism vibration on the fill system. Kaizhi Shen and coworkers [3][4][5][6][7][8] had attained fine mechanical properties using the dynamic packing technique. Qiang Fu and coworkers [9][10][11] paid more attention on the morphology and crystallization of polymer prepared with the vibration technique.…”

Section: Introductionmentioning

confidence: 99%

Effect of vibration parameters in plasticizing process on properties of polypropylene by dynamic injection molding

Wang

Huang

et al. 2013

Journal of Thermoplastic Composite Materials

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A novel self-designed dynamic injection molding machine by screw axial vibration introduced in plasticizing process was used in the preparation of polypropylene (PP) standard specimens. Under other process and same conditions, the vibration frequency and amplitude are changed in plasticizing process. The whole energy consumption in the molding process, the tensile stress, impact stress, density, and differential scanning calorimetric results of the specimens were measured. Furthermore, the effects of vibration parameters of plasticizing process on dispersion were studied with the mixture of PP and nano-calcium carbonate (CaCO 3 ) materials using scanning electron microscopy (SEM). The experimental results showed that the maximum increment of tensile stress and impact stress of the specimens are 9.8and 13.8%, respectively, by screw axial vibration introduced in plasticizing process. The maximum increment of density is 0.3%. The melt point of specimens has a significant increase of 3 C and the energy consumption of the whole processing decreases 6.6% at maximum. The SEM micrographs show that the dispersion of nano-CaCO 3 became more homogeneous compared with the steady specimens.

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Crystal phases, structure, and orientation in isotactic polypropylene after isothermal crystallization under oscillatory shear as a function of nucleation agent

Liu

Huo

2013

Colloid Polym Sci

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The effects of vibration field on crystal structures and orientation of isotactic polypropylene injection samples

Cited by 8 publications

References 30 publications

Characteristics analysis and mold design for ultrasonic-assisted injection molding

Characteristics analysis and mold design for ultrasonic-assisted injection molding

Effect of vibration parameters in plasticizing process on properties of polypropylene by dynamic injection molding

Crystal phases, structure, and orientation in isotactic polypropylene after isothermal crystallization under oscillatory shear as a function of nucleation agent

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