Boucherville, Canada
Boucherville, Canada

Time filter

Source Type

Kamal M.R.,McGill University | Chu J.,McGill University | Chu J.,Micromolding Solutions Inc. | Derdouri S.,Industrial Materials Institute of Canada | Hrymak A.,McMaster University
Plastics, Rubber and Composites | Year: 2010

A microinjection moulding machine was used to obtain micromouldings of polyoxymethylene, in order to study morphology development during the process. The method of design of experiments was used to investigate statistically the effects of processing variables on the microstructural features of the mouldings. The morphological features were identified by microtoming the samples in both transverse and longitudinal (flow) directions and observing the microtomed sections under a polarised light microscope. Morphology evolution along the flow direction was followed by microtoming the specimens along the centre plane longitudinally and sequentially. A five-layer skin core structure was identified for micromoulded polyoxymethylene. The development of the structure was explained, based on mechanisms which were similar to those proposed for conventional injection moulding. Injection speed was found to be the most significant factor affecting morphological features of the final moulding. Moreover, the average plunger velocity, which is directly related to the cavity filling flow rate, was found to have good correlation with skin layer thickness. The distributions of crystalline polymorphs were observed and explained, in light of the distributions of the flow and thermal patterns in the mould. Morphology evolution along the flow direction reflected the distribution of pressure, temperature and velocity of the polymer melt during the microinjection moulding process. The results provided some indications regarding micromoulding mould design. © 2010 Maney Publishing.


Chu J.-S.,McGill University | Chu J.-S.,Micromolding Solutions Inc. | Kamal M.R.,McGill University | Derdouri A.,Industrial Materials Institute of Canada | Hrymak A.,McMaster University
Polymer Engineering and Science | Year: 2012

The melt experiences extremely high shear rates as it travels through the very small gate, in the microinjection molding process. The combination of the high shear rates, extensive viscous heating, and the large thermal gradients has a profound influence on the characteristics of the moldings. However, many of these interactions are not clearly understood. In this study, the morphology of moldings in the gate region was observed using a polarized light microscope. Moreover, the specimens from different regions of micromoldings were analyzed using a differential scanning calorimeter (DSC). Two materials were selected for the study: polyoxymethylene (POM) and high-density polyethylene. Three special morphological features were observed in the gate region for POM but not for polyethylene. The results obtained using the DSC were explained in light of the microstructural features observed using polarized light microscopy. © 2011 Society of Plastics Engineers.


Zhang N.,University College Dublin | Chu J.S.,University College Dublin | Chu J.S.,Micromolding Solutions Inc. | Gilchrist M.D.,University College Dublin | Gilchrist M.D.,University of Ottawa
Annual Technical Conference - ANTEC, Conference Proceedings | Year: 2011

Based on reciprocating micro injection molding machine, this paper characterizes the influence of machine process parameters and its transition response from velocity control to pressure control (V-P transition) on the micro cavity filling process. The method of Design of Experiment was employed to systematically and statistically investigate the effect of machine parameters on actual cavity filling process, which was described by the defined process characteristic values (PCVs). The statistical analysis of the experiments indicated that injection speed was dominated factor affecting all PCVs in cavity filling process. It was also found that the machine V-P transition have significant effects on cavity filling.


Zhang N.,University College Dublin | Chu J.S.,University College Dublin | Chu J.S.,Micromolding Solutions Inc. | Byrne C.J.,University College Dublin | And 2 more authors.
Journal of Micromechanics and Microengineering | Year: 2012

The development of MEMS and microsystems needs a reliable mass production process to fabricate micro components with micro/nano-scale features. In our study, we used the micro injection molding process to replicate micro/nano-scale channels and ridges from a bulk metallic glass (BMG) cavity insert. High-density polyethylene was used as the molding material and the design of experiment approach was adopted to systematically and statistically investigate the relationship between machine parameters, real process conditions and replication quality. The peak cavity pressure and temperature were selected as process characteristic values to describe the real process conditions that the material experienced during the filling process. The experiments revealed that the replication of ridges, including feature edge, profile and filling height, was sensitive to the flow direction; cavity pressure and temperature both increased with holding pressure and mold temperature; replication quality can be improved by increasing cavity pressure and temperature within a certain range. The replication quality of micro/nano features is tightly related to the thermomechanical history of material experienced during the molding process. In addition, the longevity and roughness of the BMG insert were also evaluated based on the number of injection molding cycles. © 2012 IOP Publishing Ltd.


Tabkhpaz M.,University of Calgary | Mahmoodi M.,University of Calgary | Arjmand M.,University of Calgary | Sundararaj U.,University of Calgary | And 2 more authors.
Macromolecular Materials and Engineering | Year: 2015

A chaotic mixer is developed and optimized in order to overcome challenges associated with mixing polymers with high aspect ratio nano-particulates. The chaotic mixing system utilizes two cylindrical rotors to uniformly mix multi-walled carbon nanotubes (MWCNTs) with a thermoplastic. Results of the electrical conductivity and electromagnetic interference (EMI) shielding effectiveness of the chaotic mixed nanocomposites were higher than ones mixed via a commercial HAAKE mixer. MWCNTs' length was investigated and it was observed that the MWCNTs in chaotic mixed nanocomposites are longer compared to HAAKE mixer. To investigate the effects of MWCNTs' length on the electrical properties, a 3D electrical model based on random walk method was developed and examined. Obtained results suggest that the chaotic mixer has a higher potential for mixing nano particulates into thermoplastics without breaking the nanotubes and improved electrical properties, compared to other types of melt mixing techniques. In this paper, a chaotic mixer is developed and optimized to overcome challenges with mixing thermoplastics and multi-walled carbon nanotubes (MWCNT) in conventional melt mixing systems. The developed chaotic mixer uses two cylindrical rotors to disperse MWCNTs within Polystyrene. To find the optimum mixing condition in the chaotic mixer, nanocomposites in one MWCNT concentration are mixed and optimization process are done on the results. After finding the optimum condition, electrical properties measurements are performed on the samples. Results of the electrical conductivity and electromagnetic interference (EMI) shielding effectiveness of samples mixed using chaotic mixer are higher than ones mixed via a commercial HAAKE mixer. HAAKE mixer in this study is utilized as a conventional melt mixing consisting two triangular rotors. After mixing nanocomposites through both mixing systems, optical and Transmission Electron Microscopy (TEM) observation are done on the mixed samples in order to study the dispersion of MWCNTs. MWCNTs' length is also investigated and it was observed that the MWCNTs in nanocomposites mixed via chaotic mixer are longer compared to ones mixed via HAAKE mixer. To investigate the effects of MWCNTs' length on electrical conductivity of composites, a 3D electrical model based on the random walk method is also developed and compared with both previously published studies and experiments in the current paper. Considering all the presented results, chaotic mixing technique in this study has higher potential for mixing nano particulates and thermoplastics with lower breakage of nanotubes and more dispersion compared to HAAKE mixer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Tabkhpaz M.,University of Calgary | Mahmoodi M.,University of Calgary | Park S.,University of Calgary | Chu J.,Micromolding Solutions Inc.
Annual Technical Conference - ANTEC, Conference Proceedings | Year: 2014

The aim of this study was the development ofanovel chaotic mixing system utilizing two cylinder rotors rotating in a sinusoidal fashion to uniformly mix multi- walled carbon nanotubes (MWCNTs) with a polymer matrix. To investigate the infinences of important mixing parameters and optimize the mixing conditions, four major parameters were selected; and, MWCNTs were mixed with polystyrene to fabricate nanocomposites. Electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity results of the chaotic mixed nanocomposites suggest that the chaotic mixer has a higher potential for mixing nano particulates into thermoplastics, compared to other types of melt mixing techniques. Copyright © (2014) by the Society of Plastics Engineers.

Loading Micromolding Solutions Inc. collaborators
Loading Micromolding Solutions Inc. collaborators