scholarly journals Effects of Pitched Tips of Novel Kneading Disks on Melt Mixing in Twin-Screw Extrusion

2017 ◽  
Vol 44 (5) ◽  
pp. 281-288 ◽  
Author(s):  
Yasuya Nakayama ◽  
Nariyoshi Nishihira ◽  
Toshihisa Kajiwara ◽  
Hideki Tomiyama ◽  
Takahide Takeuchi ◽  
...  
Keyword(s):  
Twin Screw Extrusion ◽  
Melt Mixing ◽  
Screw Extrusion ◽  
Twin Screw

scholarly journals Correlation between Processing Parameters and Degradation of Different Polylactide Grades during Twin-Screw Extrusion

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1333 ◽  
Author(s):  
Olga Mysiukiewicz ◽  
Mateusz Barczewski ◽  
Katarzyna Skórczewska ◽  
Danuta Matykiewicz
Keyword(s):  
Molecular Weight ◽  
Processing Parameters ◽  
High Mass ◽  
Flow Index ◽  
Processing Temperature ◽  
Color Analysis ◽  
Twin Screw Extrusion ◽  
Melt Mixing ◽  
Screw Extrusion ◽  
Twin Screw

This article presents the effect of twin-screw extrusion processing parameters, including temperature and rotational speed of screws, on the structure and properties of four grades of polylactide (PLA). To evaluate the critical processing parameters for PLA and the possibilities for oxidative and thermomechanical degradation, Fourier-transform infrared spectroscopy (FT-IR), oscillatory rheological analysis, and differential scanning calorimetry (DSC) measurements were used. The influence of degradation induced by processing temperature and high shearing conditions on the quality of the biodegradable polyesters with different melt flow indexes (MFIs)was investigated by color analysis within the CIELab scale. The presented results indicate that considering the high-temperature processing of PLA, the high mass flow index and low viscosity of the polymer reduce its time of residence in the plastifying unit and therefore limit discoloration and reduction of molecular weight due to the degradation process during melt mixing, whereas the initial molecular weight of the polymer is not an essential factor.

Development of nanocellulose-reinforced PLA nanocomposite by using maleated PLA (PLA-g-MA)

2017 ◽  
Vol 31 (8) ◽  
pp. 1090-1101 ◽  
Author(s):  
Somayeh Ghasemi ◽  
Rabi Behrooz ◽  
Ismail Ghasemi ◽  
Reza Shahbazian Yassar ◽  
Fei Long
Keyword(s):  
Cellulose Nanofibers ◽  
Fracture Morphology ◽  
Poly Lactic Acid ◽  
Twin Screw Extrusion ◽  
Melt Mixing ◽  
Force Microscopy ◽  
Heat Distortion Temperature ◽  
Uniform Dispersion ◽  
Screw Extrusion ◽  
Twin Screw

The goal of this research was improving the mechanical and physical properties of poly lactic acid (PLA) using cellulose nanofiber (CNF) as reinforcing and maleated PLA (PLA-g-MA) as a compatibilizer. PLA/nanocellulose composites were prepared through melt mixing with maleated PLA (5 wt%) and two levels of cellulose nanofibers (CNFs) (3 and 5 wt%) using twin screw extrusion. Nanocomposites fracture morphology, thermal properties, crystallization behavior, and mechanical behavior were determined as a function of cellulose nanofibers and PLA grafted on maleic anhydride content using scanning electron microscopy (SEM), atomic force microscopy, heat distortion temperature (HDT), impact, and tensile testing. The SEM micrographs confirmed the uniform dispersion of CNF within PLA matrix in the presence of maleated PLA. Among nanocellulose and compatibilizer, the latter one has better role in enhancement of nanocomposites HDT. Compatibilized nanocomposites (PLA/CNF5/PLAgMA5) exhibited maximum impact strength which was 131% higher than that of neat PLA. Compared to pure PLA, 138 and 40% improvements for the tensile strength and Young’s modulus can be obtained for the resulting nanocomposite with PLA/CNF5/PLAgMA5, respectively.

scholarly journals In-Line Rheo-Optical Investigation of the Dispersion of Organoclay in a Polymer Matrix during Twin-Screw Compounding

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2128
Author(s):  
Paulo F. Teixeira ◽  
José A. Covas ◽  
Loïc Hilliou
Keyword(s):  
Local Heating ◽  
Polymer Nanocomposite ◽  
Structural Rearrangement ◽  
Particle Dispersion ◽  
Optical Investigation ◽  
Twin Screw Extrusion ◽  
Clay Particles ◽  
Clay Dispersion ◽  
Screw Extrusion ◽  
Twin Screw

The dispersion mechanisms in a clay-based polymer nanocomposite (CPNC) during twin-screw extrusion are studied by in-situ rheo-optical techniques, which relate the CPNC morphology with its viscosity. This methodology avoids the problems associated with post extrusion structural rearrangement. The polydimethylsiloxane (PDMS) matrix, which can be processed at ambient and low temperatures, is used to bypass any issues associated with thermal degradation. Local heating in the first part of the extruder allows testing of the usefulness of low matrix viscosity to enhance polymer intercalation before applying larger stresses for clay dispersion. The comparison of clay particle sizes measured in line with models for the kinetics of particle dispersion indicates that larger screw speeds promote the break-up of clay particles, whereas smaller screw speeds favor the erosion of the clay tactoids. Thus, different levels of clay dispersion are generated, which do not simply relate to a progressively better PDMS intercalation and higher clay exfoliation as screw speed is increased. Reducing the PDMS viscosity in the first mixing zone of the screw facilitates dispersion at lower screw speeds, but a complex interplay between stresses and residence times at larger screw speeds is observed. More importantly, the results underline that the use of larger stresses is inefficient per se in dispersing clay if sufficient time is not given for PDMS to intercalate the clay galleries and thus facilitate tactoid disruption or erosion.

Definition of a JA-2 Equivalent Propellant to be Produced by Continuous Solventless Extrusion

2013 ◽  
Vol 80 (3) ◽  
Author(s):  
Thelma G. Manning ◽  
Joseph Leone ◽  
Martijn Zebregs ◽  
Dinesh R. Ramlal ◽  
Chris A. van Driel
Keyword(s):  
Extrusion Process ◽  
Continuous Manufacturing ◽  
Twin Screw Extrusion ◽  
Extrusion Processing ◽  
Roll Mill ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Ballistic Properties ◽  
Definition Of ◽  
Double Base

In order to eliminate residual solvents in ammunition and to reduce the emissions of volatile organic compounds to the atmosphere, the U.S. Army ARDEC has teamed with TNO in developing a new process for the production of solventless propellant for tank ammunition. To reduce the costs of solventless propellants production, shear roll mill and continuous extrusion processing was investigated. As described in this paper JA-2 a double base propellant cannot be processed without solvent by the extrusion process. An alternative JA-2 equivalent propellant was defined. The aim of this work is to demonstrate the manufacturing of this propellant by solventless continuous twin screw extrusion processing while maintaining gun performance characteristics of conventional JA-2 propellant. This is elucidated by explicitly researching the relationship between interior ballistic properties of the gun propellant and utilizing a continuous manufacturing process. Processing conditions were established, and the propellant was manufactured accordingly. The extruded propellant has the desired properties, which resulted in a comparable gun performance as the conventional JA-2 propellant.

Sign in / Sign up

Export Citation Format

Share Document