Wall Slip of Linear Polymer Melts During Ultrasonic‐assisted Micro‐injection Molding

Gao, Shan; Qiu, Zhongjun; Ouyang, Junhao; Yang, Yujun

doi:10.1002/pen.24953

Cited by 8 publications

(10 citation statements)

References 38 publications

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“…It is known that the use of ultrasound in the processing of polymers is accompanied by the breaking of chemical bonds of macromolecules (mechanochemical destruction), which in turn leads to a decrease in the molecular weight of polymers. Similar processes have been also observed with other types of damage, including in the process of multiple polymer processing (mechanical destruction) [11][12][13][14][15][16]5].…”

Section: Original Research Articlesupporting

confidence: 57%

Effect of ultrasound exposure on melts of polyolefin compositions

Krish

Pomogova

Тверитникова

et al. 2019

Eurasian Chem. Commun.

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This study aimed at investigating the dependence of the ultrasonic (US) effects on the structure and properties of the polymer mixtures with different viscosity values. It should be noted that in the current study, polypropylene and high-pressure polyethylene of different brands were selected. The polymer composite materials (PCM) of various compositions treated with and without ultrasound were used. The formation dependence of the phase structures of polyolefin compositions on composition and viscosity of polymer systems was established. The regularity "structure-properties" of modified mixtures of polyolefins was determined. The influence of ultrasonic on the restoration process of the structure and the formation of new chemical bonds in polyolefin mixtures was discussed. The structure of the compositions of the polymer and technological conditions for their processing, which providing high physical and mechanical characteristics of PCM, were also proposed. The results indicated that to create compositions with high physical and mechanical characteristics, it is recommended to use a mixture of polyolefins containing 70% PE, modified by ultrasonic treatment.

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Section: Original Research Articlesupporting

confidence: 57%

Effect of ultrasound exposure on melts of polyolefin compositions

Krish

Pomogova

Тверитникова

et al. 2019

Eurasian Chem. Commun.

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“…Ultrasonic processing technology, as a novel molding processing technology, has been widely used in recent years for the injection molding, extrusion molding, and compression molding of polymers [9,10]. Despite different ways of applying ultrasonic energy, studies have found that ultrasounds can affect the microstructure filling performance [11], change the material properties [12], affect the extrusion swelling [13], improve the weld line strength of the plastic parts [14], and reduce the interface friction during ejection [15].…”

Section: Introductionmentioning

confidence: 99%

Micro-Ultrasonic Viscosity Model Based on Ultrasonic-Assisted Vibration Micro-Injection for High-Flow Length Ratio Parts

Lou

Xiong

2020

Polymers

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A micro-ultrasonic (MU) viscosity model based on ultrasonic-assisted vibration micro-injection for high- flow length ratio polymer parts was established. This model considered the effects of ultrasonic energy and the characteristic microdimension. Ultrasonic energy parameters (such as the ultrasonic amplitude, frequency, and ultrasound velocity), the characteristic microdimension, and the molecular chain length (MCL) were introduced into the MU viscosity model. An ultrasonic micro-injection experimental platform was built on an injection molding machine. Polypropylene (PP) filling experiments were carried out using microgrooves with different flow length ratios (depth-to-width ratios of 3:1, 5:1, and 10:1). The validity and accuracy of the MU viscosity model were examined through a filling experiment with polypropylene (PP) microgroove injection molding and by a flow pressure difference experiment with polystyrene (PS). The results showed that the MU viscosity model was in better agreement with the experimental results compared to other models. The maximum error of the MU model was 4.9%. Ultrasound-assisted vibration had great effects on the filling capacity for microgrooves with high flow length ratios (depth-to-width ratios greater than 5:1). The filling capacity increased as the ultrasonic amplitude increased.

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“…Third, the corrosion on the microcavity wall caused by cavitation damage and high frequency impact of melt under the effect of ultrasonic vibration promoted the nucleation type with the wall microstructure as the crystal nucleus [25]. Finally, during the propagation of ultrasonic vibration in the polymer melt, the internal friction and collision of polymer chains led to a heating effect on the melt, which could increase the nucleation rate [26]. Therefore, in summary, the crystallization rate of the semi-crystalline polymer was increased by ultrasonic vibration in LUμIM process.…”

Section: Resultsmentioning

confidence: 99%

The Improvement Effect and Mechanism of Longitudinal Ultrasonic Vibration on the Injection Molding Quality of a Polymeric Micro-Needle Array

2019

Self Cite

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A polymeric micro-needle array with high quality has been fabricated using a longitudinal ultrasonic-assisted micro-injection molding (LUμIM) method. To realize the practicability and stability in actual industrial processing, this paper is aimed at studying the improvement mechanism of ultrasonic vibration on the molding quality. The melt-filling process in the micro-needle array cavity is simulated, and the improvement effect of ultrasonic vibration is discussed. The enhancement effect of ultrasonic vibration on material properties of polypropylene and polymethylmethacrylate parts are experimentally investigated. The results show that in the manufacturing of the micro-needle array part using LUμIM, the mold-filling quality is improved by the enhanced melt filling capability and pressure compensation effect, which are caused by the increased corner viscosity gradient, reduced the filling time and melt viscosity under ultrasonic vibration. Material properties of both the semi-crystalline polymer and amorphous polymer could be enhanced by the transformation of micromorphology. It is proved that for a semi-crystalline polymer, this novel method could be employed as a material properties enhancement method, and an optimal excitation voltage of ultrasonic vibration is obtained to achieve the best material properties.

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Wall Slip of Linear Polymer Melts During Ultrasonic‐assisted Micro‐injection Molding

Cited by 8 publications

References 38 publications

Effect of ultrasound exposure on melts of polyolefin compositions

Effect of ultrasound exposure on melts of polyolefin compositions

Micro-Ultrasonic Viscosity Model Based on Ultrasonic-Assisted Vibration Micro-Injection for High-Flow Length Ratio Parts

The Improvement Effect and Mechanism of Longitudinal Ultrasonic Vibration on the Injection Molding Quality of a Polymeric Micro-Needle Array

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