Purpose – The purpose of this paper is to evaluate the mechanical properties of photopolymer/CB (carbon black) nanocomposite when applied in a visible-light rapid prototyping (RP) machine. Design/methodology/approach – The mechanical properties of the samples such as hardness and tensile strength along with thermal stability were analyzed. The curing time behavior of the photopolymer/CB nanocomposites was tested by using a rigid-body pendulum rheometer. The shrinkage property and dimensional stability were also analyzed using the technique according to ASTM D2566 and ASTM D1204, respectively. Findings – The results showed that the prototype fabricated from pristine photopolymer tended to exhibit poor mechanical properties and low thermal stability. However, after adding the photopolymer with various concentrations of nano-CB and dispersant in appropriate composition, the photopolymer/CB nanocomposite prototype not only reduced its curing time but also enhanced its mechanical properties, thermal stability and dimensional stability. Practical implications – The presented results can be used in a visible-light RP machine. Originality/value – The mechanical and thermal properties of photopolymer are improved with nano-CB additives for a RP system.

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The rapid prototyping technique has been developed over several decades. As the application becomes more widespread, the qualities of the parts produced by a rapid prototyping system must be considered. The area-forming rapid prototyping system is an emerging technology. This system has the advantage of a short build time but displays a weakness in the dimensional accuracy and surface roughness. To improve these weaknesses and simultaneously maintain a short build time, this study optimizes the process parameters using the grey relational Taguchi method. From the results, the best combinations of process parameters both for each quality and for multiple qualities are discovered. The optimization of process parameters is verified using the extra samples.

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ABSTRACT:In this work, an in-line viscometer to measure the viscosity of polymer melts under extrusion molding processes was developed. The in-line viscometer contains a stress sensor and a shear rate sensor which were installed between the screw and the die of an extruder. In this way, the flow line after the screw cannot be changed, unlike the present in-line capillary rheometer which can change the diameter of the pipe of the flow line and hence influence the throughput. All data acquisition is done by a computer such that the melt viscosity can be calculated automatically. The shearthinning behavior of a low-density polyethylene (LDPE) under three different temperatures is presented in all experiments. It is concluded that the melt viscosity can be effectively monitored.