Effect of oscillations during extrusion on rheology and mechanical properties of polymers

Isayev, A. I.; Wong, C. M.; Zeng, Xianlin

doi:10.1002/adv.1990.060100104

Cited by 91 publications

(63 citation statements)

References 17 publications

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“…Isayev et al 21,22 reported that during extrusion a high-intensity ultrasonic vibration could reduce die pressure and extrudate swelling as well as postpone melt fracture. In our previous work, ultrasonic vibration technology was developed to improve the processability of ultrahigh-molecular-weight polyethylene (UHMWPE).…”

Section: Introductionmentioning

confidence: 99%

Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid

Chen

Liu

2006

J of Applied Polymer Sci

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The effect of ultrasonic vibration and binary processing aid in improving the processability of metallocene linear low-density polyethylene (mLLDPE) was investigated. During extrusion, ultrasonic vibration clearly reduced the die pressure and apparent viscosity of mLLDPE but had only a slight effect on its melt fracture. The effect of diatomite/PEG binary processing aid (BPA) was excellent in reducing the viscosity and eliminating the sharkskin fracture of mLLDPE. The effect of ultrasonic vibration and binary processing aid in improving the processability of mLLDPE was synergetic. With a combination of ultrasonic vibration and a small amount of processing aid, the flowability of mLLDPE was further improved, and the critical shear rate for the onset of sharkskin fracture was increased.

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Section: Introductionmentioning

confidence: 99%

Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid

Chen

Liu

2006

J of Applied Polymer Sci

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“…20,24 It has been found that vibration affects diffusion and rate-sensitive processes 24 such as crystallization dynamics 25 and blending. 26 In polymer processing, many prospective vibration technologies such as ultrasonic vibration 27 or mechanical vibration 27,28 have been used. A detailed review on various vibration technologies is given by Ibar.…”

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confidence: 99%

“…33 At present, Haake, Brookfield, Brabander, Cotraves, and other types of small-scale internal mixers are used in labs to simulate the practical processes of polymer processing conveniently, the great differences of which lie in the controlling kernel parts. It is worth mentioning that mechanical vibration has been introduced in injection 24,27,34 as well as in the singlescrew extrusion. 27,28,35 However, there have been few reports on the application of vibration in the twin-screw extruder probably because of its complex structure.…”

mentioning

confidence: 99%

“…It is worth mentioning that mechanical vibration has been introduced in injection 24,27,34 as well as in the singlescrew extrusion. 27,28,35 However, there have been few reports on the application of vibration in the twin-screw extruder probably because of its complex structure. One of the aims of this research was to superimpose the mechanical vibration on the downscale twin-screw extruder, i.e., the common steady internal mixer, so that the influences of vibration on the rheological and mechanical properties of the blends could be studied.…”

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confidence: 99%

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Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

Wang¹,

Zhou

Zhang

et al. 2002

Adv Polym Technol

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ABSTRACT:A novel vibration internal mixer was used to prepare polypropylene/ultra high molecular weight polyethylene PP/UHMWPE blends with two additional adjustable processing parameters (vibration frequency and vibration amplitude) as compared with those prepared in the steady mode. Microscopy, mechanical tests, and differential scanning calorimetry showed that vibration influenced the blend morphology and the product properties. The good phase homogeneity of the blends might be due to the variation of shear rate either spatially or temporally in blending. Additionally, the vibration internal mixer could be used to analyze the dependency of viscosity on the shear rate. Vibration enhanced the interpenetration of UHMWPE into PP and vice versa. Subsequently, the formed crystals of two components were connected, and there was epitaxy MODIFICATION OF POLYPROPYLENE BY MELT VIBRATION BLENDINGbetween PP and UHMWPE crystals. Moreover, the crystalline aggregates, with the amorphous UHMWPE, formed a complex network-like continuous structure, which improved the elongation ratio at the break and the yield strength. The higher the vibration frequency and/or the larger the vibration amplitude at a fixed average rotation speed of the mixer, the more significant these effects were. The larger amount of the connected crystals, especially of ␤ form of PP in the bulk ␣ form PP as well as with the continuous phase structure, led to a higher tensile properties of PP/UHMWPE vibration blended. C 2002 Wiley Periodicals, Inc.

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“…Consequently, we developed the ultrasonic injection molding (UIM) system. Numerous studies have been investigated polymer processing using ultrasonic waves [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. However, except for the application of such vibration at a low frequency range [18,19], few such reports describe the application of ultrasonic vibration to injection molding.…”

Section: Introductionmentioning

confidence: 99%

Study of application of ultrasonic wave to injection molding

Sato

Itô

Koyama

2009

Polymer Engineering & Sci

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We have developed an ultrasonic injection molding (UIM) system, which applies ultrasonic waves to injection molding, as a precision injection molding technology. Molding of optical lenses showed that the lens weight increased when the ultrasonic wave was applied immediately after the resin was filled into a cavity. Results showed that, by applying ultrasonic waves, oscillatory flow was generated inside the cavity and consequently the weight of the lens was increased. The surface finish of the molded lens was also significantly improved in UIM when compared with that in conventional molding. The part of shrinkage during the packing and holding stages was suppressed by the oscillatory flow provided by the ultrasonic vibration. Because of ultrasonic energy absorption, local heating was generated inside the resin, resulting in the formation of oscillatory flow during packing and holding stages. Local heating, occurring especially between molten and skin layers, reduces the skin layer's deformation resistance. Consequently, replication during the packing and holding stages is facilitated by the UIM. Moreover, evaluation of the residual optical strain of concave lens revealed that the strain was much lower in UIM than in conventional molding. The decreased strain was attributed to the local heat generation by the ultrasonic waves. POLYM. ENG. SCI., 49:768-773, 2009. ª

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Effect of oscillations during extrusion on rheology and mechanical properties of polymers

Abstract: ABSTRACT

Cited by 91 publications

References 17 publications

Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid

Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid

Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

Study of application of ultrasonic wave to injection molding

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