Petr Lenfeld

New Silane and MAPP Coupling Agents as Natural Composites Production Systems Improvement

Still more and more applications using synthetic polymers find new material alternative in materials based on synthetic polymer filled with nature fibers mainly plant fibers. Not only in common applications but also in technical applications is possible to use nature fiber composites. But some additional modifications are necessary to perform to gain properties possible to use in technical applications. Mainly increasing adhesion between matrix and fibers is the most common intent of these additional operations. This paper deals with maleic anhydride based coupling agent and silane coupling agent effect in the polypropylene matrix and jute fiber composite and its mechanical properties. By using of silane coupling agents was achieved mechanical properties which are possible to compare with composites with glass fibers mechanical properties mainly in case of the flexural and tensile modulus and mainly was gained significant increasing of composite production system stability.

Natural Aerobic Degradation of Polylactic Acid (Composites) with Natural Fiber Additives

This paper deals with natural degradation of PLA (polylactic acid) composites with natural fiber reinforcement in non-simulated conditions. Composite material was made of PLA and 6 different types of biodegradable fibers. Fibers made from pulp, wool, bamboo, soya, flax and hemp. All samples had 20% volume of fibers. Three of each composite sample were placed in compost (aerobic surrounding) for 72 weeks. All samples were examined at the beginning every 2 weeks to observe if the degradation process occurred and all samples were examined at the end of 72 weeks period to observe results of degradation of each composite material.

Analysis of the Pressure and Shrinkage in the Mould for PLA and PLLA

Paper is focused on analysis of a local shrinkage and injection pressure of the biodegradable materials PLLA and PLA. Analysed products were prepared with thickness of 4 mm in the patent injection mould. The technological parameters of the injection moulding were established by the Taguchi method. In this article, the influence of these main technological parameters on the local shrinkage and injection pressure is evaluated.

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.

Analysis of Parameters with Influence on Material Shrinkage PLA and PLLA

The Paper deals with problematics of analysis of shrinkage biodegradable polymer materials PLA and PLLA in consequence with setup of parameters. Samples for analysis were prepared by technology of injection molding with parameters set according to Taguchi method. The parameters setting consist of injection speed, holding pressure, temperature and wall thickness. Dependency of parameters measured inside of the mold was compared to parameters set on molding machine. By this comparison we have received data for material processing in praxis.

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.

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.

Observation of Impact of Progressive Cooling System on Temperature Field Distributions on Surfaces of Injection Moulded Plastic Parts

Cooling the injection moulds with using of liquid CO2 is rated among progressive and innovative tempering systems nowadays. In the ideal case this cooling method is chosen in combination with conventional drilled or milled tempering channels where the heat transfer medium flows. These wide-spread ways of cooling are not very often effective enough and they do not provide required accuracy of heat transfer control during production by injection moulding technology. Implementation of capillary tubes that bring the liquid CO2 to critical zones enables local increasing of heat transfer. Regulation of liquid CO2 amount that is injected into mould enables removal of required heat quantity in a very short time period. In this way the homogenous rate of part cooling can be achieved which is very difficult when producing the parts with complex geometry or with combination of various wall thickness. The final mechanical and physical properties of moulded parts accrue from properties of polymer material, part design and used technological parameters. This article deals with evaluation of technological parameters, concretely the cooling parameters of both the conventional cooling method and the system utilizing the cooling potential of liquid CO2. The analysis is focused on observation of temperature field distribution on injected part surfaces.