Effect of extrusion process melt temperature on polyurethane catheter surfaces

2017 ◽  
Vol 33 (2) ◽  
pp. 180-185 ◽  
Author(s):  
B. Clemend Bovas ◽  
L. Karunamoorthy ◽  
Foo Boon Chuan
Keyword(s):  
Extrusion Process ◽  
Melt Temperature ◽  
Polyurethane Catheter

Influence of Melt Temperature on Structure of Polyacrylonitrile in Ionic Liquids during Plasticized Melt Spinning Process

2012 ◽  
Vol 268-270 ◽  
pp. 483-486
Author(s):  
Yin Cai Tian ◽  
Ke Qing Han ◽  
Wen Hui Zhang ◽  
Jing Jie Zhang ◽  
Rui Zhang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Melt Spinning ◽  
Extrusion Process ◽  
Heat Emission ◽  
Processing Efficiency ◽  
Melt Temperature ◽  
Stabilization Process ◽  
In Situ Modification ◽  
Spinning Process ◽  
Dehydrogenation Reactions

The carbon fiber has excellent properties; however, the high cost limited its wide application. Here we report a novel process to reduce the heat emission during stabilization by in situ modification of spinning melt. In this paper, the effect of extruding temperature on the structures of PAN in the PAN/ILs melt was investigated by twin-screw extruder. FTIR and UV-vis absorption spectra of modified samples showed the formation of C=C and C=N group, which indicated the occurrence of cyclization and dehydrogenation reactions of PAN during extrusion process. The degree of cyclization was calculated from DSC test and the degree of cyclization can be up to 24.5% with the residence time of 14 min at 210 oC, which could decrease the heat release in the subsequent stabilization process during carbon fiber production. Therefore, this method should be benefit to improve the processing efficiency during stabilization process.

An Experimental Investigation on Surface Quality Extruded Wood-Polypropylene Composite

2012 ◽  
Vol 428 ◽  
pp. 89-93 ◽  
Author(s):  
Ehsan Soury ◽  
Amir Hossein Behravesh ◽  
Nathan Jafarian Jam ◽  
Ali Haghtalab
Keyword(s):  
Surface Quality ◽  
Polymeric Materials ◽  
Melt Flow Index ◽  
Extrusion Process ◽  
Diameter Ratio ◽  
Flow Index ◽  
Screw Speed ◽  
Melt Temperature ◽  
Wood Content ◽  
Length To Diameter Ratio

This paper presents an experimental study on surface quality (roughness) for extruded wood plastic composites (WPC) in an extrusion process. A problem that usually occurs in production of extruded parts of polymeric materials, and in special case of WPC, is flow instabilities at the extrusion die exit. The instabilities lead to production of profiles with unacceptable surface quality. In this paper, the influences of the important material and process parameters on the surface quality are investigated. The variable parameters were selected as wood content, polymer melt flow index (MFI), screw speed, melt temperature, die diameter and finally length-to-diameter ratio of the die land. The experiments specified that increasing die land length-to-diameter ratio (L/D), die temperature and wood content and decreasing screw speed and polymer MFI lead to improve the surface quality.

SSEM-AG Computer Model for Optimization of Polymer Extrusion

2006 ◽  
Author(s):  
K. Wilczynski ◽  
A. Nastaj
Keyword(s):  
Power Consumption ◽  
Extrusion Process ◽  
Global Optimum ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Melt Temperature ◽  
Local Optima ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Screw Extrusion

The optimization of an extrusion process is a conflicting, multi-objective problem. It is complicated by the number of variables (screw/die geometry, operating conditions, material data) and their non-linear relations, as well as by the opposing criteria, for example extrusion throughput and power consumption. It is difficult to find the global optimum for the process avoiding local optima. There are two approaches to solve the problem, experimental and using a mathematical model of extrusion. Optimization techniques based on an experimentation are time-consuming and very expensive. In this paper we present an optimization methodology based on the Genetic Algorithms (AG), where response surface is given by the extrusion model. A mathematical Single-Screw Extrusion Model SSEM developed at the Warsaw University of Technology is used to predict the extruder behavior, and AG approach is used for optimization. An integrated SSEM-AG system was developed to study optimization of the single-screw extrusion process. Three design criteria (output variables) are selected for optimization: maximum extrusion throughput, minimum power consumption and low melt temperature. As input variables, screw speed, barrel temperature and screw channel depth are chosen.

scholarly journals Evaluation of melt quality during polymer extrusion

2021 ◽  
pp. 9-14
Author(s):  
Volodymyr Novodvorskyi ◽  
Mykola Shved ◽  
Dmytro Shved
Keyword(s):  
Statistical Evaluation ◽  
Extrusion Process ◽  
Polymer Materials ◽  
Temperature Uniformity ◽  
Melt Temperature ◽  
Working Bodies ◽  
Industry Sectors ◽  
Potential Use ◽  
Statistical Criteria

Polymer materials are widely spread and used in all industry sectors. The operating properties of polymer products make them practically indispensable in various industries. They have acquired widespread popularity and their production volumes are predicted to grow every year. The extrusion of polymers is one of the main methods for their processing. The melt uniformity is one of the main factors that influence the quality of the products and is determined by the level of mixing, i.e., by the redistribution of additives in a dispersion medium when these additives are introduced into the main polymer. The influence of working conditions, geometry of working bodies and other parameters on the melt temperature uniformity was determined. Nowadays, there are a lot of methods for determining the melt uniformity. They can be used indirectly in or after the extrusion process and can be short or long lasting, which in fact determines the acceptability of each of the methods. To determine the melt uniformity, statistical evaluation methods, which have been verified by many experiments and are well known, are often used. The analysis showed that the mixing index is most sensitive among the criteria described. Although statistical criteria of evaluating the melt uniformity are widespread, it is better to use parameters that allow the state of the mixture to be analyzed directly in the work process for the extrusion of polymers, to identify those that depend on the mixing process. Methods and criteria for verifying the melt quality were analyzed and potential use of their temperature uniformity for measuring and evaluating the melt quality directly in the extrusion process, to eliminate the costly sampling process, was determined.

scholarly journals A Calculation Model for Cooling Rate of Aluminum Alloy Melts during Continuous Rheo-Extrusion

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5684
Author(s):  
Yu Wang ◽  
Minqiang Gao ◽  
Bowei Yang ◽  
Jingyuan Bai ◽  
Renguo Guan
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
Cooling Rate ◽  
Cooling Water ◽  
Extrusion Process ◽  
Calculation Model ◽  
Melt Temperature ◽  
Extrusion Technology ◽  
The Relationship ◽  
Microstructure Characteristic

The melt temperature of aluminum alloys plays a significant role in determining the microstructure characteristic during continuous rheo-extrusion. However, it is difficult to measure the actual melt temperature in the roll-shoe gap. In this work, based on the basic theory of heat transfer, a calculation model for heat transfer coefficient of cooling water/roll interface and melt/roll interface is established. In addition, the relationship between the temperature at the melt/roll interface and the velocity of cooling water is investigated. Combined with the CALPHAD calculation, the melt temperature during solidification in the continuous rheo-extrusion process is calculated. Using this model, the cooling rate of an Al–6Mg (wt.%) alloy melt prepared by continuous rheo-extrusion is estimated to be 10.3 K/s. This model used to determine the melt parameters during solidification provides a reference for optimizing the production process of continuous rheo-extrusion technology.

Dynamic studies of silicide-mediated crystallization of amorphous silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1352-1353
Author(s):  
C. Hayzelden ◽  
J. L. Batstone
Keyword(s):  
Ion Implantation ◽  
Solid Phase ◽  
Metallic Phase ◽  
Single Crystal Substrate ◽  
Free Electrons ◽  
Melt Temperature ◽  
Transmission Electron ◽  
Crystal Substrate ◽  
High Resolution Tem

Epitaxial reordering of amorphous Si(a-Si) on an underlying single-crystal substrate occurs well below the melt temperature by the process of solid phase epitaxial growth (SPEG). Growth of crystalline Si(c-Si) is known to be enhanced by the presence of small amounts of a metallic phase, presumably due to an interaction of the free electrons of the metal with the covalent Si bonds near the growing interface. Ion implantation of Ni was shown to lower the crystallization temperature of an a-Si thin film by approximately 200°C. Using in situ transmission electron microscopy (TEM), precipitates of NiSi2 formed within the a-Si film during annealing, were observed to migrate, leaving a trail of epitaxial c-Si. High resolution TEM revealed an epitaxial NiSi2/Si(l11) interface which was Type A. We discuss here the enhanced nucleation of c-Si and subsequent silicide-mediated SPEG of Ni-implanted a-Si.Thin films of a-Si, 950 Å thick, were deposited onto Si(100) wafers capped with 1000Å of a-SiO2. Ion implantation produced sharply peaked Ni concentrations of 4×l020 and 2×l021 ions cm−3, in the center of the films.

A morphological and energy-dispersive x-ray spectroscopy (EDS) investigation of separator-grade cellophane

1994 ◽  
Vol 52 ◽  
pp. 430-431
Author(s):  
Michael E. Rock ◽  
Vern Kennedy ◽  
Bhaskar Deodhar ◽  
Thomas G. Stoebe
Keyword(s):  
Extrusion Process ◽  
Morphological Characterization ◽  
Energy Dispersive ◽  
Regenerated Cellulose ◽  
Battery System ◽  
X Ray ◽  
Functional Differences ◽  
Transmission Electron ◽  
Separator Material ◽  
Underwater Target

Cellophane is a composite polymer material, made up of regenerated cellulose (usually derived from wood pulp) which has been chemically transformed into "viscose", then formed into a (1 mil thickness) transparent sheet through an extrusion process. Although primarily produced for the food industry, cellophane's use as a separator material in the silver-zinc secondary battery system has proved to be another important market. We examined 14 samples from five producers of cellophane, which are being evaluated as the separator material for a silver/zinc alkaline battery system in an autonomous underwater target vehicle. Our intent was to identify structural and/or chemical differences between samples which could be related to the functional differences seen in the lifetimes of these various battery separators. The unused cellophane samples were examined by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Cellophane samples were cross sectioned (125-150 nm) using a diamond knife on a RMC MT-6000 ultramicrotome. Sections were examined in a Philips 430-T TEM at 200 kV. Analysis included morphological characterization, and EDS (for chemical composition). EDS was performed using an EDAX windowless detector.

Sign in / Sign up

Export Citation Format

Share Document