Residence time distribution in non‐intermeshing counter‐rotating twin‐screw extruders

Chen, L.; Hu, Guohua; Lindt, J. T.

doi:10.1002/pen.760350706

Cited by 33 publications

(13 citation statements)

References 10 publications

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“…22 In this work, the change of pellet size was directly observed along the screw after splitting the barrel. The mean residence time of reaction medium corresponding to each port T re was accurately measured according to the procedure suggested by Chen et al 23 and the reaction time at each sample port T r was determined by eq. (3):…”

Section: Twin-screw Extruder Systemmentioning

confidence: 99%

Kinetics study on melt grafting copolymerization of LLDPE with acid monomers using reactive extrusion method

Shi

Zhu

Cai

et al. 2006

J of Applied Polymer Sci

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Graft copolymerization in the molten state is of fundamental importance as a probe of chemical modification and reactive compatibilization. However, few grafting kinetics studies on reactive extrusion were carried out for the difficulties as expected. In this work, the macromolecular peroxide-induced grafting of acrylic acid and methyl methacrylate onto linear low density polyethylene by reactive extrusion was chosen as the model system for the kinetics study; the samples were taken out from the barrel at five ports along screw axis and analyzed by FTIR, 1 H NMR, and ESR. For the first time, the time-evolution of reaction rate, the reaction order, and the activation energy of graft copolymerization and homopolymerization in the twin screw extruder were directly obtained. On the basis of these results, the general reaction mechanism was tentatively proposed. It was demonstrated that an amount of chain propagation free radicals could keep alive for several minutes even the peroxides completely decomposed and the addition of monomer to polymeric radicals was the rate-controlled step for the graft copolymerization. The results presented here revealed that the relative importance of graft copolymerization compared with homopolymerization mainly depended on the monomer solubility and reactivity, while the process parameters such as reaction temperature also influenced the reaction tendency.

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Section: Twin-screw Extruder Systemmentioning

confidence: 99%

Kinetics study on melt grafting copolymerization of LLDPE with acid monomers using reactive extrusion method

Shi

Zhu

Cai

et al. 2006

J of Applied Polymer Sci

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“…In separate work (Chen et al, 1993b), the validity of Eqs. 2 and 3 were further confirmed using nonintermeshing counterrotating twin-screw zone combinations.…”

Section: Results and Discussion Experimental Verification Of The Theorymentioning

confidence: 99%

Residence time distribution in screw extruders

Chen

Zao-qi

Hu³

1993

AIChE Journal

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A companion article (Chen and Hu, 1993a) discussed a statistical theory that for a system consisting of two closed subsystems, the residence time density (RTD) functions of the two subsystems will bestatistically independent, ifa two-dimensional perfect mixing exists at the subsystem boundary. In this case, the overall RTD function is related to that for individualsubsystems through the convolution integral. This theory has been validated experimentally using two die-screw combinations.Based on this theory, a predictive RTD model for an intermeshing counterrotating twin-screw extruder has been developed. The screw in the longitudinal direction has been treated as C-chambers in series. The overall RTD of leakage flows has been calculated from the RTDs of these individual chambers and then converted into the RTD of the extruder. The predicted RTD has been tested against experimental results with success.

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“…32,33 A secondorder transfer function that corresponds to the mixing occurring in the screw and the die zones of the extruder was used. In the Laplace domain, it can be represented as …”

Section: -31mentioning

confidence: 99%

Combinatorial development of polymer nanocomposites using transient processing conditions in twin screw extrusion

et al. 2008

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in Wiley InterScience (www.interscience.wiley.com).A new approach is presented for combinatorial development of polymer nanocomposites with compositional gradients (CGs). The CGs were developed using transient processing conditions in twin screw extrusion with small quantities of expensive nanoscale fillers. Convolution of step input with normalized residence volume distributions (RVDs) was used to establish the processing-structure relationship for the CGs. The normalized RVD was established as a process characteristic independent of processing conditions and measured in situ using an optical probe. The CG determined nondestructively using the new combinatorial approach was validated through comparison with more time-consuming and destructive thermogravimetric analysis. The CG could also be established with relatively inexpensive microscale fillers using the normalized RVD obtained with nanoscale fillers, suggesting that transient effects of the mixing process are independent of the size of the filler. Finally, structure-property relationship of combinatorially developed polymer nanocomposites was established by characterizing their dynamic mechanical behavior (storage modulus, G 0 , and loss modulus, G 00 ). The dynamic mechanical behavior of the combinatorially developed composites correlated well with the batch-processed ones, indicating that the transient mixing conditions in extrusion do not affect the material properties.

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Residence time distribution in non‐intermeshing counter‐rotating twin‐screw extruders

Cited by 33 publications

References 10 publications

Kinetics study on melt grafting copolymerization of LLDPE with acid monomers using reactive extrusion method

Kinetics study on melt grafting copolymerization of LLDPE with acid monomers using reactive extrusion method

Residence time distribution in screw extruders

Combinatorial development of polymer nanocomposites using transient processing conditions in twin screw extrusion

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