Determination of Pressure in the Mold Cavity of Injected Semi-Crystalline Thermoplastics

2012 ◽  
Author(s):  
Xavier Tardif ◽  
Vincent Sobotka ◽  
Nicolas Boyard ◽  
Philippe Le Bot ◽  
Didier Delaunay
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Mold Cavity ◽  
Numerical Comparison ◽  
Ejection Time ◽  
Strongly Coupled ◽  
Kinetics Of ◽  
Pressure Analysis

Injection molding is the most used process for thermoplastic part manufacturing. This process is commonly divided into four steps: injection, packing, cooling and ejection. During the packing step, an amount of material gets into the mold cavity to compensate for shrinkage of the polymer mainly due to the crystallization. Once the gate is frozen, polymer is subjected to isochoric cooling while the pressure of the polymer is higher than atmospheric pressure. Improving the quality of the injected part requires prediction of the shrinkage, warpage and residual stress and pressure impacts deeply on the morphology and consequently on the shape of the final part. The pressure decrease during the isochoric phase also determines the ejection time. However, description of the behavior of the polymer during packing and isochoric steps needs an accurate model that considers coupling between heat transfer and crystallization and also a good knowledge of the behavior (specific volume and crystallization kinetics) of the polymer under high pressure. Some studies have already underlined the influence of shear rate on the kinetics of crystallization. Here, based on a pressure analysis and an experimental-numerical comparison, we confirm crystallization is strongly coupled to flow history.

scholarly journals Single-sided NMR for the measurement of the degree of cross-linking and curing

2018 ◽  
Vol 7 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Norbert Halmen ◽  
Christoph Kugler ◽  
Eduard Kraus ◽  
Benjamin Baudrit ◽  
Thomas Hochrein ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Curing Kinetics ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
First Results ◽  
Non Destructive ◽  
Kinetics Of ◽  
Good Agreement

Abstract. The degree of cross-linking and curing is one of the most important values concerning the quality of cross-linked polyethylene (PE-X) and the functionality of adhesives and resin-based components. Up to now, the measurement of this property has mostly been time-consuming and usually destructive. Within the shown work the feasibility of single-sided nuclear magnetic resonance (NMR) for the non-destructive determination of the degree of cross-linking and curing as process monitoring was investigated. First results indicate the possibility of distinguishing between PE-X samples with different degrees of cross-linking. The homogeneity of the samples and the curing kinetics of adhesives can also be monitored. The measurements show good agreement with reference tests (wet chemical analysis, differential scanning calorimetry, dielectric analysis). Furthermore, the influence of sample temperature on the characteristic relaxation times can be observed.

DEVELOPING OF MATLAB APPLICATION FOR DETERMINING THE REACTION KINETICS OF RUBBER VULCANIZATION PROCESS

2021 ◽  
Author(s):  
Dario Balaban ◽  
◽  
Jelena Lubura ◽  
Predrag Kojić ◽  
Jelena Pavličević ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Reaction Kinetics ◽  
Kinetic Parameters ◽  
Degradation Process ◽  
Complex Process ◽  
Quality Of Fit ◽  
Kinetics Of ◽  
Vulcanization Process

Rubber vulcanization is kinetically a complex process, since it consists of two simultaneous reactions: curing and degradation. To determine reaction kinetics, it is necessary to determine a kinetic model which describes the process adequately. Proposed kinetic model has six adjustable parameters. In order to determine kinetic parameters of the proposed kinetic model, commercially available rubber gum was used. Oscillating disc rheometer was used to investigate experimental dependence of torque on time, at six temperatures in the range from 130 to 180 °C, with a step of 10 °C. Matlab application, built via App Designer feature, was developed in order to fit the experimental data to the proposed kinetic model. Developed Matlab application, consisting of two tabs, enables user to upload raw rheometer data, perform manual fitting or automatic fitting (manual or automatic estimation of initial values of adjustable parameters), test the effect of constant values of some kinetic parameters on the overall quality of fit, visualize the dependence of kinetic parameters on temperature and to determine the values of Arrhenius expression for curing and degradation process. Both fitting methods were proven to be efficient; overall determination coefficient and MAPE value for automatic and manual fitting methods were >0.99 and <1%, and >0.999 and <1%, respectively. Arrhenius parameters were also determined with high accuracy (R2>0.98). Developed application enables simple and efficient determination of kinetic parameters by means of different fitting methods, simultaneous fitting of data on all temperatures, and testing the effect of constant kinetic parameters values on fitting results

Boiling Heat Transfer on Small Diameter Tube Bundle

2010 ◽  
Vol 2 ◽  
pp. 41-52 ◽  
Author(s):  
Ebenezer Adom ◽  
Peter Kew ◽  
Keith Cornwell
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Tube Bundle ◽  
Small Diameter ◽  
Heat Fluxes ◽  
Tube Bank ◽  
Central Column ◽  
The Heat Transfer Coefficient ◽  
Outside Diameter

An experimental study has been carried out using a tube bank representing a section of a tube bundle. The bank comprised 3 columns each of 10 stainless steel electrically heated tubes of 3mm outside diameter with pitch to diameter ratio of 1.5 in an in-line arrangement. Flow rate through the test section was controlled. Each tube in the central column was instrumented to permit determination of the tube temperature and heat flux, hence permitting calculation of the heat transfer coefficient. These tests were carried out using distilled water at nominal atmospheric pressure over a range of heat fluxes between 6 - 21 kW/m2. Results of the heat transfer tests are presented and compared with correlations used for conventionally sized bundles. Correlations developed for large tube bundle overestimate the experimental results.

A Model to Evaluate Heat Transfer to a Particle From Thermal Plasma

2001 ◽  
Author(s):  
Sameer D. Samudra ◽  
Milind A. Jog
Keyword(s):  
Heat Transfer ◽  
Spherical Particle ◽  
Thermal Plasma ◽  
Manufacturing Systems ◽  
Accurate Determination ◽  
Ionized Gas ◽  
Ceramic Particles

Abstract In many plasma-aided manufacturing systems, metallic or ceramic particles are introduced in a thermal plasma. The heat transfer from the plasma to the particle, in part, governs the quality of the products. To design thermal plasma-aided manufacturing systems and to predict their performance, accurate determination of particle heat transfer is necessary. In this paper, a spherical particle introduced in an ionized gas made up of electrons, ions, and neutrals is considered. A model to accurately determine heat transfer to the particle is developed.

scholarly journals The influence of the mold quality and injection pressure on the product quality

2018 ◽  
Vol 210 ◽  
pp. 02043
Author(s):  
Michal Stanek ◽  
Martin Reznicek ◽  
Lenka Hylova ◽  
Roman Grund
Keyword(s):  
Product Quality ◽  
Surface Quality ◽  
Injection Pressure ◽  
Significant Problem ◽  
Mold Cavity ◽  
Product Price ◽  
Product Surface ◽  
Mold Quality

This study deals with the study of the influence of injection pressure parameters and the quality of the surface of the mold cavity on the final quality of the product surface. This issue represents a significant problem, especially in the area of the mold production and the determination of its product price. The final price is closely linked just to the surface quality. This study is concentrated on three basic qualities of machining, namely Ra 0.1, Ra 0.8 and Ra 1.6. The possibilities of the replication of the surface of the mold cavity are then combined with various values of injection pressure, which has also the inconsiderable influence on surface replication. Total results show the influence of injection pressure and its most suitable value for obtaining the best identities of both surfaces.

scholarly journals Determination of Sorption Properties of Heavy Metals in Various Biosorbents

2018 ◽  
Vol 25 (2) ◽  
pp. 201-216 ◽  
Author(s):  
Andrzej Kłos
Keyword(s):  
Data Interpretation ◽  
Copper Cation ◽  
Reaction Model ◽  
Static System ◽  
Heavy Metal Sorption ◽  
Pseudo Second Order ◽  
High Degree ◽  
Kinetics Of

Abstract Various techniques of determination of properties of physicochemical processes of heavy metal sorption in biosorbents were analysed. The methods of preparing and storing samples, conditions of experiment performance, as well as the methods of data interpretation were discussed. Two procedures of study were analysed: (1) in the static system of biosorbent-solution contact and (2) in the system of dynamic flow of solution. Copper cation sorption was studied. The effect of consecutive stages of the study on the quality of final results was shown. A high degree of uncertainty of the sorption capacity assessment was reported, which was dependent on the manner of conducting the study. The application of the pseudo-second order reaction model was substantiated to describe kinetics of cation-exchange sorption and the model of Langmuir isotherm to describe equilibria. The study conducted reveals that in order to perform comparative analyses, it is necessary to establish a joint concept of conducting studies and the interpretation of results.

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