Pawel Palutkiewicz

The Impact of Mould Temperature and Blowing Agent Content on Structure and Properties of Injection Moulded Parts

The investigation of the influence of mould temperature and blowing agent percentage on structure, and selected properties (weight, mechanical properties, surface state - gloss and colour) of moulded parts from HDPE was the aim of this work. The structure of moulded parts in cross-section perpendicular and parallel to the direction of polymer flow, and quantitative assessment of porous structure using microscopic image analysis were carried out. It was shown that the content of blowing agent in polymer influences not only the amount of pores in the part core, but also the thickness of solid skin. Lower mould temperature favors the formation of a fine porous structure. The formation of the porous structure influenced slightly the weight and mechanical properties of moulded parts. With the increase in blowing agent content, the gloss of parts decreased and also caused the change in their colour. Parts with higher amount of blowing agent were brighter.

The investigation of selected properties of the porous moulded parts from talc-filled PP composites

The investigation of the influence of chemical blowing agent addition and talc filler on structure and selected properties (weight, thickness, mechanical properties, surface state – gloss and colour – and thermal conductivity) of moulded parts from PP was the aim of this work. Microscopic investigations were made using mould with cavities of variable height. Addition of blowing agents to polymer material permits reducing of the injection cycle to the injection phase and cooling. Investigations showed that talc addition permits to obtain fine-cellular structure in moulded parts with blowing agent. It is possible, because talc can act as a nucleating agent, which has been shown in literature. As a result, moulded parts with blowing agent and talc had low weight, good mechanical properties compared to solid, unfilled parts. Main disadvantage of using blowing agent and talc is worsening of gloss and colour changing.

The Influence of Blowing Agent Addition, Glass Fiber Filler Content and Mold Temperature on Selected Properties, Surface State and Structure of Injection Molded Parts from Polyamide 6

The effects of blowing agent and glass fiber addition and also mold temperature on selected properties of PA6 molded parts was presented in this work. Blowing agent was dosed to plastic in amounts 0.5 – 1%, and glass fiber was added in amounts 15 – 30%. Furthermore, molded parts from unfilled and unfoamed PA6 was also investigated. The experimental plan was prepared using Design of Experiments (DoE) method. The results of selected part properties: molded parts weight, thickness, hardness, impact strength, tensile strength, elongation at maximum force, and also surface state of molded parts (gloss and color) was presented. The article also presents microscopic investigations (using SEM method) of molded parts with blowing agent and glass fiber. It was found, that the glass fiber content has a larger impact on mechanical properties of parts than addition of blowing agent. The use of the blowing agent in an amount of 1% wt. will allow the reduce injection cycle time by reducing the hold pressure and hold time, without significant worsening their properties. The mold temperature has an impact especially on the gloss of molded parts and the pore size.

The new method of manufacturing porous castings from styrene–acrylic dispersion

This work presents an innovative method for producing porous castings from polymer dispersion with wood flour. The method described for forming porous castings from blends, in which the aqueous dispersions of polymers are binders, enables the manufacturing of wood-like products with a cork-like structure. The casting technology and selected properties of finished castings (density, compression strength) are presented. The structurual investigations of the obtained castings are also presented.

Special construction of the screw for plastics processing

lutkiewicz@ipp.pcz.pl), dr inż. Włodzimierz Baranowski – Zakład Przetwórstwa Polimerów, Instytut Technologii Mechanicznych, Wydział Inżynierii Mechanicznej i Informatyki Politechniki Częstochowskiej Przedstawiono innowacyjne rozwiązanie konstrukcji ślimaka do przetwórstwa tworzyw sztucznych. Opisywany ślimak jest przedmiotem wynalazku zgłoszonego w Polskim Urzędzie Patentowym. Jest to ślimak do przetwórstwa tworzyw sztucznych, zwłaszcza barwionych, oraz tworzyw napełnianych i tworzyw charakteryzujących się małą różnicą pomiędzy temperaturą uplastyczniania i temperaturą degradacji. W artykule omówiono cechy charakterystyczne ślimaka oraz sposób jego wykonania. SŁOWA KLUCZOWE: wytłaczanie, przetwórstwo tworzyw, ślimak do przetwórstwa tworzyw, uplastycznianie

Effectiveness of Blowing Agents in the Cellular Injection Molding Process

The study was undertaken to investigate the effect of the type and content of blowing agents in the polymeric materials being processed on the structure and selected physical and mechanical properties of the obtained injection molded parts. In the study of the cellular injection molding process, three standard and generally available thermoplastics were used. In the experiments, the blowing agent content (0–2.0% by mass, i.e. 0, 0.4, 0.8 and 2.0% (wt)) fed into the polymer being processed was adopted as a variable factor. In the present study, the blowing agents with the endothermic decomposition characteristics and exothermic decomposition characteristics, coming in a granulated form with a diameter ranging from 1.2 to 3 mm were used. Based on the results of investigating porosity, porous structure image analysis as well as microscopic examination of the structure was shown. It has been found, that the favorable content of the blowing agent in the polymeric material should be of up to 0.8% wt.. With such content of the blowing agent in the polymeric material, favorable strength properties are retained in porous parts, the pore distribution is uniform and the pores have similar sizes.