Preparation and characterization of microcellular injection molded foams from high-performance blends based on PPS-modified PPBESK

2017 ◽  
Vol 30 (4) ◽  
pp. 480-488 ◽  
Author(s):  
Na Wen ◽  
Tao Liu ◽  
Bin Xiang ◽  
Yajie Lei ◽  
Shikai Luo
Keyword(s):  
Injection Molding ◽  
High Performance ◽  
Polyphenylene Sulfide ◽  
Mechanical And Thermal Properties ◽  
Melt Mixing ◽  
Average Cell Size ◽  
Average Cell ◽  
Molding Method ◽  
Microcellular Foams ◽  
Microcellular Injection Molding

Obtaining foams of poly-containing biphenyl moieties (phthalazinone ether sulfone ketone; PPBESK) by applying the microcellular injection molding method is very difficult because of the high melt viscosity of the materials used. To overcome this limitation, polyphenylene sulfide (PPS) was used to improve the rheological properties of PPBESK. PPBESK/PPS blends of different proportions were prepared using the melt mixing method. The rheological behavior, phase behavior, interfacial tension, and mechanical properties of the blends were then investigated. The results clearly indicate that PPS can improve the melt processability of PPBESK. However, due to the strong adhesion between the PPS and PPBESK phases, the introduction of PPS did not cause any loss of the mechanical and thermal properties of PPBESK. Accordingly, microcellular foams from modified PPBESK were prepared by microcellular injection molding with supercritical nitrogen as foaming agent. A closed cell microcellular morphology with an average cell size of 17.7 um and cell density of 109 cells cm−3 was obtained.

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.

Microcellular injection molding of recycled poly(ethylene terephthalate) blends with chain extenders and nanoclay

2014 ◽  
Vol 34 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Yottha Srithep ◽  
Lih-Sheng Turng
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Ethylene Terephthalate ◽  
Average Cell Size ◽  
Recycled Pet ◽  
Average Cell ◽  
Poly Ethylene Terephthalate ◽  
Microcellular Injection Molding ◽  
Chain Extenders ◽  
Poly Ethylene

Abstract Poly(ethylene terephthalate) (PET) resin is one of the most widely used thermoplastics, especially in packaging. Due to thermal and hydrolytic degradations, recycled PET (RPET) exhibits poor mechanical properties and lacks moldability. The effects of adding chain extender (CE) and nanoclay to RPET were investigated. Melt blending of RPET with CE was performed in a thermokinetic mixer (K-mixer). The blended materials were then prepared via solid and microcellular injection molding processes. The effects of CE loading levels and the simultaneous addition of nanoclay on the thermal and mechanical properties and cell morphology of the microcellular components were noted. The addition of 1.3% CE enhanced the tensile properties and viscosity of RPET. The higher amount of CE (at 3%) enhanced the viscosity, but the margin of improvement in mechanical properties diminished. While the solid RPET and CE blends were fairly ductile, the samples with nanoclay and all microcellular specimens showed brittle fractural behavior. Finally, nanoclay and the increase of CE content decreased the average cell size and enlarged the cell density of the microcellular samples.

Effect of Nanoclay on the Physical-Mechanical and Thermal Properties and Microstructure of Extruded Noncross-Linked LDPE Nanocomposite Foams

2011 ◽  
Vol 471-472 ◽  
pp. 751-756 ◽  
Author(s):  
F. Zandi ◽  
M. Rezaei ◽  
A. Kasiri
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Cell Size ◽  
Flame Retardancy ◽  
Image Analyzer ◽  
Mechanical And Thermal Properties ◽  
Average Cell Size ◽  
Cell Size Distribution ◽  
Average Cell ◽  
Nanocomposite Foams

Novel noncross-linked low density polyethylene (LDPE) foams were produced by extrusion process. In this study the effects of Organophilic Montmorillonite (OMMT) nanoclay (DK1) on thermal conductivity, flame retardancy, morphological and mechanical properties of LDPE foams have been investigated. Nanoclay dispersion in LDPE foam structure was examined by X-ray diffraction (XRD), microstructure was observed by an optical microscope and analyzed by Bel View image analyzer, thermal conductivity was studied by a simple transient method, mechanical properties was investigated using a tensile-compression Zwick-Roell machine as well as the flame retardancy of the samples was examined by flammability test. The optimum nanoclay content was determined by comparison of the properties in nanocomposite and neat LDPE foams. Due to the presence of nanoclay in the foam and decreasing the cell nucleation energy around the nanoclay, the average cell size was decreased as well as the cell density and microstructure uniformity was increased. In XRD patterns of LDPE nanocomposite foams, OMMT (DK1) characteristic peak was not observed as evidence of nanoclay intercalation-exfoliation in the polymer matrix, which led to the production of foams with homogenous microstructure. Furthermore, this nanocomposites showed lower thermal conductivity compared to neat LDPE foam, which can be attributed to the cell size reduction as well as narrow cell size distribution in nanocomposite foams. Compression test results demonstrated that LDPE nanocomposite foams with proper clay contents have improved mechanical properties (Young’s modulus, compressive strength). Furthermore due to the presence of DK1 nanoclay, LDPE foam showed a good char formation as an evidence of their flame retardancy.

scholarly journals Preparation and recycling of polymer eco-composites I. comparison of the conventional molding techniques for preparation of polymer eco-composites

2009 ◽  
Vol 28 (1) ◽  
pp. 99 ◽  
Author(s):  
Vineta Srebrenkoska ◽  
Gordana Bogoeva Gaceva ◽  
Dimko Dimeski
Keyword(s):  
Mechanical Properties ◽  
Maleic Anhydride ◽  
Injection Molding ◽  
High Performance ◽  
Natural Fiber ◽  
Construction Materials ◽  
Hibiscus Cannabinus ◽  
Mechanical And Thermal Properties ◽  
Rice Hulls ◽  
Kenaf Fibers

The interest in natural fiber-reinforced polymer composites is growing rapidly due to their high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. In this study, the compression and injection molding of polypropylene (PP) and polylactic acid (PLA) based composites reinforced with rice hulls or kenaf fibers was carried out and their basic properties were examined. Rice hulls from rice processing plants and natural lignocellulosic kenaf fibers from the bast of the plant Hibiscus Cannabinus represent renewable sources that could be utilized for composites. Maleic anhydride grafted PP (MAPP) and maleic anhydride grafted PLA (MAPLA) were used as coupling agents (CA) to improve the compatibility and adhesion between the fibers and the matrix. Composites containing 30 wt % reinforcement were manufactured by compression and injection molding, and their mechanical and thermal properties were compared. It was found that the techniques applied for manufacturing of the eco-composites under certain processing conditions did not induce significant changes of the mechanical properties. The flexural strength of the compressed composite sample based on PP and kenaf is 51. 3 MPa in comparison with 46.7 MPa for the same composite produced by injection molding technique. Particularly, PP-based composites were less sensitive to processing cycles than PLA-based composites. The experimental results suggest that the compression and injection molding are promising techniques for processing of eco-composites. Moreover, the PP-based composites and PLA-based composites can be processed by compression and injection molding. Both composites are suitable for applications as construction materials.

Foam morphology and sound transmission loss of foamed wood flour/low-density polyethylene (LDPE)/nanoclay composites

2017 ◽  
Vol 31 (11) ◽  
pp. 1470-1482 ◽  
Author(s):  
Fariba Molkara ◽  
Saeed Kazemi Najafi ◽  
Ismail Ghasemi
Keyword(s):  
Transmission Loss ◽  
Wood Flour ◽  
Sound Transmission ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Sound Transmission Loss ◽  
Average Cell Size ◽  
Average Cell ◽  
Molding Method ◽  
Foam Morphology

In this research, the effects of foaming and of nanoclay on foam morphology and soundproofing of wood flour/low-density polyethylene (LDPE) composites were investigated. For this purpose, LDPE, wood flour, foaming agent, and nanoclay were mixed in an internal mixer to produce test samples. The standard circular samples were made using compression molding method in a hot press machine. Sound transmission loss (STL) was measured by an impedance tube. Results showed that foaming and nanoclay increase the STL of the composites at frequencies above 2000 Hz. The biggest increase in STL has been found for the foamed composites containing nanoclay. The addition of nanoclay decreased the average cell size and increased the cell density of foamed composites.

scholarly journals Retrieval of phytoplankton size from bio-optical measurements: theory and applications

2010 ◽  
Vol 8 (58) ◽  
pp. 650-660 ◽  
Author(s):  
Shovonlal Roy ◽  
Shubha Sathyendranath ◽  
Trevor Platt
Keyword(s):  
Absorption Coefficient ◽  
Cell Size ◽  
High Performance ◽  
Optical Measurements ◽  
Sensitivity Analyses ◽  
Average Cell Size ◽  
Average Cell ◽  
Field Samples ◽  
Phytoplankton Cells

The absorption coefficient of a substance distributed as discrete particles in suspension is less than that of the same material dissolved uniformly in a medium—a phenomenon commonly referred to as the flattening effect. The decrease in the absorption coefficient owing to flattening effect depends on the concentration of the absorbing pigment inside the particle, the specific absorption coefficient of the pigment within the particle, and on the diameter of the particle, if the particles are assumed to be spherical. For phytoplankton cells in the ocean, with diameters ranging from less than 1 µm to more than 100 µm, the flattening effect is variable, and sometimes pronounced, as has been well documented in the literature. Here, we demonstrate how the in vivo absorption coefficient of phytoplankton cells per unit concentration of its major pigment, chlorophyll a , can be used to determine the average cell size of the phytoplankton population. Sensitivity analyses are carried out to evaluate the errors in the estimated diameter owing to potential errors in the model assumptions. Cell sizes computed for field samples using the model are compared qualitatively with indirect estimates of size classes derived from high performance liquid chromatography data. Also, the results are compared quantitatively against measurements of cell size in laboratory cultures. The method developed is easy-to-apply as an operational tool for in situ observations, and has the potential for application to remote sensing of ocean colour data.

Effect of Processing Parameters on Cellular Structures and Mechanical Properties of PMMA Microcellular Foams

2005 ◽  
Vol 24 (4) ◽  
pp. 177-195 ◽  
Author(s):  
Jin Fu ◽  
Choonghee Jo ◽  
Hani E. Naguib
Keyword(s):  
Mechanical Properties ◽  
Saturation Pressure ◽  
Viscoelastic Model ◽  
Batch Process ◽  
Processing Parameters ◽  
Analytical Models ◽  
Elastic Behavior ◽  
Average Cell Size ◽  
Average Cell ◽  
Microcellular Foams

In this study, the effect of processing parameters on the cellular morphologies and mechanical properties of PMMA microcellular foams is investigated. Microcellular closed cell Poly(methyl-methacrylate) (PMMA) foams were prepared using a two stage batch process method. The foam structure was controlled by altering the processing parameters such as foaming temperature, foaming time and saturation pressure. The foam morphologies were characterized in terms of the average cell size, cell density and foam density. Elastic modulus, tensile strength and elongation at break were studied as functions of the different foaming parameters. The mechanical properties were found to be greatly affected by the foaming parameters and vary with changing the cell morphologies. The experimental results were compared with existing analytical models to validate them and to predict the mechanical properties of microcellular polymeric PMMA foams prepared with different processing parameters. A constitutive equation for the nonlinear elastic behavior of polymeric microcellular foams was developed based on the Maxwell viscoelastic model. The results of this work can help designers optimize the foam processing parameters and achieve desired foam morphology and mechanical properties.

Effect of Processing Parameters on the Cellular Morphology and Mechanical Properties of Thermoplastic Polyolefin (TPO) Microcellular Foams

2006 ◽  
Author(s):  
Steven Wong ◽  
Hani E. Naguib ◽  
Chul B. Park
Keyword(s):  
Mechanical Properties ◽  
Saturation Pressure ◽  
Batch Process ◽  
Processing Parameters ◽  
Average Cell Size ◽  
Average Cell ◽  
Microcellular Foams ◽  
Closed Cell ◽  
Foaming Temperature ◽  
Thermoplastic Polyolefin

In this study, the effects of processing parameters on the cellular morphologies and mechanical properties of TPO70 (Thermoplastic Polyolefin) microcellular foams are investigated. Microcellular closed cell TPO70 foams were prepared using a two-stage batch process method. The microstructure of these foamed samples was controlled by carefully altering the processing parameters such as saturation pressure, foaming temperature and foaming time. The foam morphologies were characterized in terms of the cell density, foam density and average cell size. Elastic modulus, tensile strength, and elongation at break of the foamed TPO70 samples were measured for different cell morphologies. The findings show that the mechanical properties were significantly affected by the foaming parameters which varied with the cell morphologies. The experimental results can be used to predict the microstructure and mechanical properties of microcellular polymeric TPO70 foams prepared with different processing parameters.

scholarly journals High-Performance of a Thick-Walled Polyamide Composite Produced by Microcellular Injection Molding

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4199
Author(s):  
Dariusz Sykutera ◽  
Piotr Czyżewski ◽  
Piotr Szewczykowski
Keyword(s):  
Injection Molding ◽  
High Performance ◽  
Flow Direction ◽  
Cell Diameter ◽  
Injection Molding Process ◽  
Polyamide 66 ◽  
Molding Process ◽  
Sem Images ◽  
Microcellular Injection Molding ◽  
Sink Mark

Lightweight moldings obtained by microcellular injection molding (MIM) are of great significance for saving materials and reducing energy consumption. For thick-walled parts, the standard injection molding process brings some defects, including a sink mark, warpage, and high shrinkage. Polyamide 66 (PA66)/glass fiber (GF) thick-walled moldings were prepared by MuCell® technology. The influences of moldings thickness (6 and 8.4 mm) and applied nitrogen pressure (16 and 20 MPa) on the morphology and mechanical properties were studied. Finally, the microcellular structure with a small cell diameter of about 30 μm was confirmed. Despite a significant time reduction of the holding phase (to 0.3 s), high-performance PA66 GF30 foamed moldings without sink marks and warpage were obtained. The excellent strength properties and favorable impact resistance while reducing the weight of thick-walled moldings were achieved. The main reason for the good results of polyamide composite was the orientation of the fibers in the flow direction and the large number of small nitrogen cells in the core and transition zone. The structure gradient was analysed and confirmed with scanning electron microscopy (SEM) images, X-ray micro computed tomography (micro CT) and finite element method (FEM) simulation.

Thermal conductivities, mechanical and thermal properties of graphite nanoplatelets/polyphenylene sulfide composites

RSC Advances ◽  
2014 ◽  
Vol 4 (42) ◽  
pp. 22101-22105 ◽  
Author(s):  
Junwei Gu ◽  
Junjie Du ◽  
Jing Dang ◽  
Wangchang Geng ◽  
Sihai Hu ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Ball Milling ◽  
Methanesulfonic Acid ◽  
Compression Molding ◽  
Polyphenylene Sulfide ◽  
Mechanical And Thermal Properties ◽  
Graphite Nanoplatelets ◽  
Molding Method ◽  
Mechanical Ball Milling ◽  
Thermal Conductivities

Functionalized pristine graphite nanoplatelets (fGNPs) by methanesulfonic acid/isopropyltrioleictitanate (MSA/NDZ-105) are used to fabricate fGNPs/polyphenylene sulfide (fGNPs/PPS) composites by mechanical ball milling followed by a compression molding method.

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