scholarly journals Structural Foams of Biobased Isosorbide-Containing Copolycarbonate

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Stefan Zepnik ◽  
Daniel Sander ◽  
Stephan Kabasci ◽  
Christian Hopmann
Keyword(s):  
Injection Molding ◽  
Weight Reduction ◽  
Polymer Processing ◽  
Foam Core ◽  
Processing Technologies ◽  
Blowing Agent ◽  
Foam Properties ◽  
Injection Molded ◽  
Foam Injection Molding ◽  
Structural Foams

Isosorbide-containing copolycarbonate (Bio-PC) is a partly biobased alternative to conventional bisphenol A (BPA) based polycarbonate (PC). Conventional PC is widely used in polymer processing technologies including thermoplastic foaming such as foam injection molding. At present, no detailed data is available concerning the foam injection molding behavior and foam properties of Bio-PC. This contribution provides first results on injection-molded foams based on isosorbide-containing PC. The structural foams were produced by using an endothermic chemical blowing agent (CBA) masterbatch and the low pressure foam injection molding method. The influence of weight reduction and blowing agent concentration on general foam properties such as density, morphology, and mechanical properties was studied. The test specimens consist of a foam core in the center and compact symmetrical shell layers on the sides. The thickness of the foam core increases with increasing weight reduction irrespective of the CBA concentration. The specific (mechanical) bending properties are significantly improved and the specific tensile properties can almost be maintained while reducing the density of the injection-molded parts.

Influence of Technological Parameters on Material Flow

2015 ◽  
Vol 1120-1121 ◽  
pp. 1194-1197 ◽  
Author(s):  
Michal Stanek ◽  
David Manas ◽  
Miroslav Manas ◽  
Vojtech Senkerik ◽  
Adam Skrobak ◽  
...  
Keyword(s):  
Injection Molding ◽  
Injection Pressure ◽  
Polymer Processing ◽  
Injection Rate ◽  
Cavity Surface ◽  
Injection Molding Process ◽  
Technological Parameters ◽  
Molding Process ◽  
Processing Technologies

Injection molding is one of the most extended polymer processing technologies. It enables the manufacture of final products, which do not require any further operations. The tools used for their production – the injection molds – are very complicated assemblies that are made using several technologies and materials. Delivery of polymer melts into the mold cavity is the most important stage of the injection molding process. The fluidity of polymers is affected by many parameters Inc. mold design. Evaluation of set of data obtained by experiments in which the testing conditions were widely changed shows that the quality of cavity surface and technological parameters (injection rate, injection pressure and gate size) has substantial influence on the length of flow.

Preparation of Microcellular Injection-Molded Foams Using Different Types of Low-Pressure Gases via a New Foam Injection Molding Technology

2019 ◽  
Vol 58 (38) ◽  
pp. 17824-17832 ◽  
Author(s):  
Long Wang ◽  
Yuma Wakatsuki ◽  
Yuta Hikima ◽  
Masahiro Ohshima ◽  
Atsushi Yusa ◽  
...  
Keyword(s):  
Injection Molding ◽  
Low Pressure ◽  
Different Types ◽  
Injection Molded ◽  
Foam Injection Molding

scholarly journals A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1896 ◽  
Author(s):  
Llewelyn ◽  
Rees ◽  
Griffiths ◽  
Jacobi
Keyword(s):  
Injection Molding ◽  
Mechanical Characteristics ◽  
Low Pressure ◽  
Microcellular Foam ◽  
Foaming Agents ◽  
Blowing Agent ◽  
Weight Saving ◽  
Microcellular Foams ◽  
Foam Injection Molding ◽  
Foam Production

Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical N2) and a novel hybrid foaming (combination of said chemical and physical foaming agents). Three weight-saving levels were produced with the varying foaming methods and compared to conventional injection molding. The unfilled PP foams produced through chemical blowing agent exhibited the strongest mechanical characteristics due to larger skin wall thicknesses, while the weakest were that of the talc-filled PP through the hybrid foaming technique. However, the hybrid foaming produced superior microcellular foams for both PPs due to calcium carbonate (CaCO3) enhancing the nucleation phase.

Comparative study of chemical and physical foaming methods for injection-molded thermoplastic polyurethane

2016 ◽  
Vol 53 (4) ◽  
pp. 373-388 ◽  
Author(s):  
Hrishikesh A Kharbas ◽  
Jason D McNulty ◽  
Thomas Ellingham ◽  
Cyrus Thompson ◽  
Mihai Manitiu ◽  
...  
Keyword(s):  
Injection Molding ◽  
Thermoplastic Polyurethane ◽  
Polyurethane Foams ◽  
Average Cell Size ◽  
Average Cell ◽  
Blowing Agents ◽  
Blowing Agent ◽  
Microcellular Injection Molding ◽  
Injection Molded ◽  
Commercial Applications

Thermoplastic polyurethane is one of the most versatile thermoplastic materials being used in a myriad of industrial and commercial applications. Thermoplastic polyurethane foams are finding new applications in various industries including the furniture, automotive, sportswear, and packaging industries because of their easy processability and desirable customizable properties. In this study, three methods of manufacturing injection molded low density foams were investigated and compared: (1) using chemical blowing agents, (2) using microcellular injection molding with N2 as the blowing agent, and (3) using a combination of supercritical gas-laden pellets injection molding foaming technology and microcellular injection molding processes using co-blowing agents CO2 and N2. Thermal, rheological, microscopic imaging, and mechanical testing were carried out on the molded samples with increasing amounts of blowing agents. The results showed that the use of physical blowing agents yielded softer foams, while the use of CO2 and N2 as co-blowing agents helped to manufacture foams with lower bulk densities, better microstructures, and lower hysteresis loss ratios. Chemical blowing agent-foamed thermoplastic polyurethane showed an earlier onset of degradation. The average cell size decreased and the cell density increased with the use of co-blowing agents. A further increase in gas saturation levels showed a degradation of microstructure by cell coalescence.

Effect of processing condition on properties of polylactic acid parts obtained by foam injection molding

2016 ◽  
Vol 53 (5) ◽  
pp. 491-502 ◽  
Author(s):  
Valentina Volpe ◽  
Roberto Pantani
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Polylactic Acid ◽  
Flow Rate ◽  
Flexural Modulus ◽  
Processing Condition ◽  
Blowing Agent ◽  
Injection Flow Rate ◽  
Injection Flow ◽  
Foam Injection Molding

Foam injection molding is a processing technology particularly interesting for biodegradable polymers, which present a very narrow processing window, with the suitable processing temperatures close to the degradation conditions. The addition of a physical blowing agent, besides decreasing the final part weight, reduces both the viscosity and the glass transition temperature of the polymer melt, allowing the processability of these materials at lower temperatures. In this work, structural foams of polylactic acid with nitrogen as physical blowing agent were obtained by foam injection molding. In particular, the effects of back pressure, namely the pressure imposed inside of the cylinder when the screw is returning back to prepare a new amount of material to be injected, and of the injection flow rate on foaming and mechanical properties of the molded parts was assessed. It was found that the samples molded adopting a higher injection flow rate are shorter than those injected at lower flow rate, and this result was ascribed to the large compressibility of the injected shot. As far as the mechanical properties of the foamed parts, it was found that the modulus decreases with decreasing density. However, the density reduction is not the only significant parameter, but also the morphology of the foams should be taken into account in order to justify the differences between tensile and flexural modulus.

Injection-molded microcellular PLA/graphite nanocomposites with dramatically enhanced mechanical and electrical properties for ultra-efficient EMI shielding applications

2018 ◽  
Vol 6 (25) ◽  
pp. 6847-6859 ◽  
Author(s):  
Guilong Wang ◽  
Guoqun Zhao ◽  
Sai Wang ◽  
Lei Zhang ◽  
Chul B. Park
Keyword(s):  
Electrical Properties ◽  
Injection Molding ◽  
Emi Shielding ◽  
Mechanical And Electrical Properties ◽  
Injection Molded ◽  
Foam Injection Molding ◽  
Graphite Nanocomposites

Lightweight and strong microcellular PLA/graphite nanocomposites with ultra-efficient EMI shielding performance were prepared using mold-opening foam injection molding.

scholarly journals Near-Infrared Spectroscopic Monitoring Technique of Physical Blowing Agent Concentration in Foam Injection Molding Processes

Seikei-Kakou ◽  
2021 ◽  
Vol 33 (5) ◽  
pp. 176-181
Author(s):  
Shunsuke Hosoe ◽  
Yuta Hikima ◽  
Masahiro Ohshima ◽  
Masahiro Watari ◽  
Akihiro Naito
Keyword(s):  
Injection Molding ◽  
Near Infrared ◽  
Blowing Agent ◽  
Spectroscopic Monitoring ◽  
Monitoring Technique ◽  
Infrared Spectroscopic ◽  
Foam Injection Molding

Foam Extrusion

2006 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Carbon Dioxide ◽  
Injection Molding ◽  
Cell Structure ◽  
Initial Pressure ◽  
Structural Foam ◽  
Molten Polymer ◽  
Blowing Agents ◽  
Foam Extrusion ◽  
Blowing Agent ◽  
Foam Injection Molding

There are two processes used in the production of thermoplastic foams, namely, foam extrusion and structural foam injection molding (Benning 1969; Frisch and Saunders 1973). Foam extrusion, in which either chemical or physical blowing agents are used, is the focus of this chapter. Investigations of foam extrusion have dealt with the type and choice of process equipment (Collins and Brown 1973; Knau and Collins 1974; Senn and Shenefiel 1971; Wacehter 1970), the effect of die design (Fehn 1967; Han and Ma 1983b), the effect of blowing agents on foaming characteristics (Burt 1978, 1979; Han and Ma 1983b; Hansen 1962; Ma and Han 1983), and relationships between the foam density, cell geometry, and mechanical properties (Croft 1964; Kanakkanatt 1973; Mehta and Colombo 1976; Meinecke and Clark 1973). Chemical blowing agents are generally low-molecular-weight organic compounds, which decompose at and above a critical temperature and thereby release a gas (or gases), for example, nitrogen, carbon dioxide, or carbon monoxide. Examples of physical blowing agents include nitrogen, carbon dioxide, fluorocarbons (e.g., trichlorofluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane), pentane, etc. They are introduced as a component of the polymer charge or under pressure into the molten polymer in the barrel of the extruder. It is extremely important to control the formation and growth of gas bubbles in order to produce foams of uniform quality (i.e., uniform cell structure). The fundamental questions one may ask in thermoplastic foam processing are: (1) What is the optimal concentration of blowing agent in order to have the minimum number of open cells and thus the best achievable mechanical property? (2) How many bubbles will be nucleated at the instant of nucleation? (3) What is the critical pressure at which bubbles nucleate in a molten polymer? (4) What are the processing–property relationships in foam extrusion and structural foam injection molding? Understandably, the answers to such questions depend, among many factors, on: (1) the solubility of the blowing agent in a molten polymer, (2) the diffusivity of the blowing agent in a molten polymer, (3) the concentration of the blowing agent in the mixture with a molten polymer, (4) the chemical structure of the polymers, (5) the initial pressure of the system, and (6) the equilibrium (or initial) temperature of the system.

scholarly journals Shrinkage and Warpage Minimization of Glass-Fiber-Reinforced Polyamide 6 Parts by Microcellular Foam Injection Molding

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 889 ◽  
Author(s):  
Youngjae Ryu ◽  
Joo Seong Sohn ◽  
Chang-Seok Yun ◽  
Sung Woon Cha
Keyword(s):  
Injection Molding ◽  
Polyamide 6 ◽  
Injection Molding Process ◽  
Microcellular Foam ◽  
Molding Process ◽  
Glass Fiber Reinforced ◽  
Molded Parts ◽  
Injection Molded ◽  
Process Factors ◽  
Foam Injection Molding

Shrinkage and warpage of injection-molded parts can be minimized by applying microcellular foaming technology to the injection molding process. However, unlike the conventional injection molding process, the optimal conditions of the microcellular foam injection molding process are elusive because of core differences such as gas injection. Therefore, this study aims to derive process conditions to minimize the shrinkage and warpage of microcellular foam injection-molded parts made of glass fiber reinforced polyamide 6 (PA6/GF). Process factors and levels were first determined, with experiments planned accordingly. We simulated designed experiments using injection molding analysis software, and the results were analyzed using the Taguchi method, analysis of variance (ANOVA), and response surface methodology (RSM), with the ANOVA analysis being ultimately demonstrating the influence of the factors. We derived and verified the optimal combination of process factors and levels for minimizing both shrinkage and warpage using the Taguchi method and RSM. In addition, the mechanical properties and cell morphology of PA6/GF, which change with microcellular foam injection molding, were confirmed.

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