Luboš Bĕhálek

Conformal Cooling of the Injection Moulds

Paper deals with the diagnosis of operating conditions for injection moulding tools. Paper specifically deals with the conformal cooling of injection moulds for its production is using the direct metal laser sintering method. It´s quite modern method about injection mould cooling system design to improve cooling intensity. Paper also deals with the evaluation of the temperature fields in the area of the mould shape parts in comparison with the common cooling system with drilled channels namely at using steel or copper alloys for punch production. Moreover there is also evaluated cooling method influence on properties and also injection part morphological structure by methods of wide angle X-ray scattering and differential scanning calorimetry.

Gate Location and its Impact to Flowing Characteristics of Plastic Moldings

Paper deals with simulation analysis of thermoplastic flowing in plastics product. As there is a demand in plastic products, plastic industries are growing in a fastest rate. Hence plastic injection molding process begins in manufacturing of complex shapes, in this process optimum gate location is one of the important criteria in mold design. Knowledge of ideal flow properties of thermoplastic materials give us a very good starting position for design of thermoplastics products which will be made by injection molding. By simulation software Plastic Advisor was compared injection parameters for the mold with varying gate locations. Simulated thermoplastic product is made from polycarbonate and is using for the drum washing machine as console window.

Use of Composite Materials for FDM 3D Print Technology

This article deals with specific polymer composites modified for the Fused Deposition Modelling (FDM) which is a 3D print technology. These two phase systems involve thermoplastic matrix filled with natural fibres. The crucial demand of this progressive technology is put on the accuracy of the semi-product formed into the filament shape. To reach the smooth production of 3D prototypes the filament should have a constant diameter. In the article, individual steps of the polymer composite pelletization and following pre-processing and processing activities are described. Among these steps the extrusion of the filaments belongs and subsequent print test on “RepRap” device accompanied by optimization of building parameters. Tensile specimens were chosen for print with regard to maps mechanical properties of this newly developed material which was the final stage of this work. Tensile test curves were then compared with those graphs which can be found for the material produced by conventional technologies such as injection moulding.

Differential Scanning Calorimetry as a Tool for Quality Testing of Plastics

Differential scanning calorimetry (DSC) is the most frequently used method from thermal analysis to characterize plastics and which can be applied not only in the R&D but also in the industrial praxis as input and output control. This paper deals with the most important DSC application which arises from results of applied and contractual research at Technical university of Liberec. In the paper are introduced examples of its utilization for plastics identification and characterization, for analysis influence of plastics processing process parameters on their quality, to describe crystallization kinetics and so on.

Crystallization and Thermal Degradation of Green Nanocomposites Based on Lignin Coated Cellulose Nanocrystals and Poly(Lactic Acid)

Cellulose is almost inexhaustible source of raw material comprising at least one-third of all biomass matter. Through deconstruction of cellulose hierarchical structure can be extracted highly crystalline cellulose nanocrystals (CNC) with impressive properties. However, the main barrier in the processing of the nanocomposites based on CNC is their inhomogeneous dispersion and distribution in the non-polar polymer matrix. In this paper is this problem addressed by use of novel hydrophobic lignin coated CNC as a biobased nucleation agents in poly (lactic acid) (PLA) nanocomposites. These green nanocomposites based on natural plant derived substances have enormous potential to replace materials originated from non-renewable resources and show promise of providing degradation back into the environment when they are no longer needed. Resulted composites prepared by twin screw extrusion and injection moulding were characterized by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of L-CNC (1, 2 and 3 wt. %) into PLA increased melt crystallization enthalpy and decreases the cold crystallization enthalpy. The degree of crystallinity (cc) increased from 5.6 % (virgin PLA) to 8.5 % (PLA/1-L-CNC), 10.3 % (PLA/2-L-CNC) and 10.7 % (PLA/3-L-CNC). The wide range of degradation temperatures of lignin coating has been observed starting at 100 °C.

Thermal Degradation of the Thermoplastic Elastomers during the Injection Moulding Process

The thermal degradation of the thermoplastic elastomers (TPEs) during the injection moulding process – depending on the melt temperature and residence time of the processed material within the barrel of the injection unit, was studied on the basis of oxidation induction time evaluation (isothermal OIT) of the moulded parts (according to ISO 11357-6) and their physical and mechanical properties, according to ISO 1183-1, ISO 37 and ISO 7619-1. TPEs with different chemical compositions intended for automotive, industrial and medical applications were analysed during the study of the thermal degradation process.

Influence of Different Coupling Agent Type on Processibility and Applicability of Polymer Composites

The contribution deals with the processibility and applicability of polymer composite systems based on polypropylene matrix. The composites were filled with vegetable fibres (particularly the cotton fibres, coir fibres, hemp fibres and jute fibres) and the interface between the polymeric matrix and the natural fibres was modified using two types of coupling agents (the organosilane coupling agent and maleic anhydride grafted polypropylene). For evaluation of the final impact of all three phases presence on the processibility of the polymer composite the melt flow behaviour was analyzed (MFI analysis according to ISO 1133) for the filler concentration of 10, 20 and 30 wt. %. This study involves also the natural fibre surface profile analyses (based on SEM observation) and the applicability of created composite materials was determined using the heat deflection temperature (HDT analysis according to ISO 75).

Dynamic-Mechanical Properties of Polymer Composites with the Short and Long Glass Fibers

Nowadays the use of glass fibers in development of polymer composites creates a very interesting research area aiming to achieve multiple outputs to different applications. The use of thermoplastic composites reinforced with glass fibers in engineering applications like automotive industry has increased considerably in the last few decades. These composites combine high mechanical strength properties, reduced mass, easy processing and corrosion resistance. The shifting from metals to engineering composites pushes towards lightweighting benefits which results in improved fuel efficiency. This paper is focused on the assessment of polymer composites properties on the basis of polyamides (PA6.6) with the short (GF) and long glass fibres (LGF). The bulk characterization of all samples has been made by Dynamic Mechanical Analysis (DMA) depending on temperature, stress frequency and the weight percentage of reinforcement in matrix.

Adhesion Additive Influence on Polyamide Nanopolymer Composite Properties

In recent years there are efforts to use polymer nanofibers and their properties in polymer composites. The aim of such efforts is to develop composites with nanofibers fillers which would be able into a great extend to take advantage of any unique properties of polymer nanofibers. Such area of research belongs into the research project whose part is also to incorporate nanofibers and nanoparticles into composite with thermoplastic matrix. The important part of research represents also finding the suitable additives to ensure sufficient adhesion between filler and polymer matrix which is crucial for the final composite properties.

Two Component Parts Hardness Optimization Regarding Production Systems

This paper deals with optimization of mechanical properties mainly hardness and stiffness of flexible part of two component injection molded part regarding production systems. Optimization is performed on two material combinations: Thermoplastic - thermoplastic elastomere and thermoplastic - silicone. Polymers used for two component part are suitable for medical applications.