Properties of bead foams with increased heat stability made from the engineering polymer polybutylene terephthalate (E-PBT) (original) (raw)
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Expanded polyamide 12 bead foams (ePA) thermo-mechanical properties of molded parts
PROCEEDINGS OF THE 35TH INTERNATIONAL CONFERENCE OF THE POLYMER PROCESSING SOCIETY (PPS-35)
The demand for bead foam products, typically made from expanded polystyrene (ePS) or expanded polypropylene (ePP), has risen sharply in the past. Bead foam products made from engineering thermoplastics with superior thermomechanical properties compared to existing products, such as a polyamide could open up completely new fields of application. Like other engineering thermoplastics, polyamide shows challenging properties with regard to foaming, such as a low melt strength and a narrow processing window. The present work shows the thermo-mechanical properties of expanded bead foams from polyamide 12 (ePA). The molded parts, with a density less than 100 g/l, were compared to commercially available ePP in three-point bending tests. The bending modulus is about 4 times higher compared to ePP, although the molding can be still improved. Furthermore, the thermo-mechanical properties are tested with dynamic mechanical analysis. ePA exhibit a good thermal stability up to 150 °C, with nearly unchanging dynamic mechanical properties in the tested range. In comparison to ePP, with a thermal resistance up to 100 °C, ePA bead foams show significantly better properties and could displace commonly used compact polyamide parts as well as ePP parts in the car.
Expanded Polycarbonate (EPC)—A New Generation of High-Temperature Engineering Bead Foams
Polymers
Bead foams serve in a wide variety of applications, from insulation and packaging to midsoles in shoes. However, the currently used materials are limited to somewhat low temperature or exhibit significant changes in modulus in the temperature range of many applications due to their glass transition. By comparison, polycarbonate (PC) exhibits almost constant mechanics for temperatures up to 130 °C. Therefore, it appears as an advantageous base material for bead foams. The aim of the publication is to provide comprehensive data on the properties of expanded PC (EPC) in comparison to already commercially available expanded polypropylene, EPP, and expanded polyethylene-terephthalate, EPET. A special focus is set on the thermo-mechanical properties as these are the most lacking features in current materials. In this frame, dynamic mechanical analysis, and tensile, bending, compression and impact tests at room temperature (RT), 80 °C, and 110 °C are conducted for the three materials of th...
Insights into the Bead Fusion Mechanism of Expanded Polybutylene Terephthalate (E-PBT)
Polymers
Expandable polystyrene (EPS) and expanded polypropylene (EPP) dominate the bead foam market. As the low thermal performance of EPS and EPP limits application at elevated temperatures novel solutions such as expanded polybutylene terephthalate (E-PBT) are gaining importance. To produce parts, individual beads are typically molded by hot steam. While molding of EPP is well-understood and related to two distinct melting temperatures, the mechanisms of E-PBT are different. E-PBT shows only one melting peak and can surprisingly only be molded when adding chain extender (CE). This publication therefore aims to understand the impact of thermal properties of E-PBT on its molding behavior. Detailed differential scanning calorimetry was performed on neat and chain extended E-PBT. The crystallinity of the outer layer and center of the bead was similar. Thus, a former hypothesis that a completely amorphous bead layer enables molding, was discarded. However, the incorporation of CE remarkably re...
Advances in Low Density Expanded Polyolefin Bead Foam for Shape Molding and Fabrication
2007
Advances in the field of polyolefin resins in the area of PP copolymers, PE homopolymers, and PP & PE blends have allowed for the creation of new and improved polyolefin bead foams. These polyolefin bead foams are capable of improved performance due to the advancements that have been made in the area of polyolefin resin catalyst systems and additives. The benefits of polyolefin bead foams allow for lower densities to be used where higher density extruded foams are currently being utilized. Polyolefin bead foam products are capable of being produced in densities ranging from 12 g/l (0.75 lb/ft 3) up to 250 g/l (15.5 lb/ft 3). Advances in the area of bead size and shape have allowed for improved production capabilities, and are making polyolefin bead foams cost competitive vs. traditional extruded foams. The multidirectional energy management ability of polyolefin bead foams also makes them attractive for use in traditional shape molded applications as well as fabricated applications.
Thermochimica Acta, 2017
Foam injection molded samples were produced from recycled polyethylene-terephthalate using endothermic and exothermic foaming agents at different mold temperatures. The foam structure was analyzed by computer tomography and optical microscopy. The morphological properties of samples were analyzed by differential scanning calorimetry, using the three-phase model. Viscosities of the melts were changed during processing by endothermic and exothermic foaming agents, and as a result different foam structures were formed. Relationships between mold temperature and porosity were found. Morphologies of the samples made with different foaming agents were different, also due to the different cooling rates caused by the endothermic and exothermic foaming reactions.
Journal of Applied Polymer Science, 2010
The foamability of two food-grade, highmolecular-weight poly(ethylene terephthalate)s (PETs) was investigated. Sorption tests were performed to determine the solubility and diffusivity of N 2 and CO 2 in molten polymers at 250 C with a magnetic suspension balance. Pressure-volume-temperature (pVT) data were also measured and used in the context of the Sanchez-Lacombe equation of state to predict the sorption isotherms. The thermal properties, in terms of the glass-transition, melting, and crystallization temperatures, were measured by differential scanning calorimetry analysis on the two high-molecularweight PETs and, for comparison, on a bottle-grade PET. The rheological properties were measured to asses the improvement of the high-molecular-weight PET with respect to the bottle-grade one. Expansion tests were performed on the two high-molecular-weight grades and bot-tle-grade PETs with a batch foaming process with N 2 , CO 2 , and an 80-20 wt % N 2 -CO 2 mixture used as blowing agents. The whole processing window was explored in terms of temperature, pressure drop rate, and saturation pressure. The results of the foaming experiments were correlated to gas sorption and the thermal and rheological properties of the polymers in the molten state. The results proved the feasibility of foam processing these two highmolecular-weight grades, which gave, when compared to the bottle grade at specific foaming conditions, very low densities and fine morphologies.
Journal of Applied Polymer Science, 2020
Poly(phthalazinone ether ketone) (PPEK) is an amorphous thermoplastic polymer with a high glass transition temperature (T g) exceeding 250 C. We describe the preparation of foams from PPEK and characterize their properties. PPEK foams were prepared using dichloromethane as a foaming agent. The foaming agent was swollen into discs of the PPEK, which were then foamed by heating. Foams could be prepared at temperatures far below the T g of the PPEK due to plasticization of the polymer by the foaming agent. Foams with densities ranging from 0.1 to 0.65 g/cm 3 were prepared. Their thermal conductivity and modulus (measured approximately by indentation tests) were found to decrease with density, and the trends were similar to those expected from existing models. The foams could be annealed at 200 C without collapse suggesting that they may be useful in structural or insulation applications where stability at high temperature is essential.
2007
The morphology and compressive properties of EPDM foam were investigated against foaming temperatures (i.e 140, 150 and 160 o C). The blowing agent used in this study was sodium bicarbonate. The rubber compositions were expanded and cured using conventional compression moulding technique via heat transfer foaming process. The morphology of EPDM foam was characterized with respect to the cell size, relative foam density and crosslink density. Meanwhile the compressive properties were characterized using compression load-deflection and compression set testing. Increase in foaming temperature resulted in larger cell size. The crosslink densities in EPDM foam were determined using Flory-Rhener equation and results indicated that the crosslink density has slightly decreased with increasing foaming temperature. The relative foam density also showed decreasing when the foaming temperature was increased. For mechanical properties, the highest foam density has resulted in the highest compressive stress. Compression stress at 50 % strain decreased with increasing foaming temperature. It was also found that the compression set decreased with increasing foaming temperature. The results showed that the morphology and compressive properties of the EPDM foam can be controlled closely by the foaming temperature.
Optimization of foaming process using triblock polyimides with thermally labile blocks
Polymer, 2001
Triblock polyamic acid was synthesized from the reaction of amine-terminated polystyrene with 4,4 H-oxydianiline and pyromellitic dianhydride in N-methyl-2-pyrrolidone. IR and TGA were used to determine optimum curing conditions, in which imidization was completed and the thermally labile polystyrene block was intact. From the thermomechanical analysis (TMA), it was identified that the resulting triblock polyimide film showed contraction at several points over the temperature range of 50-400ЊC. The first contraction at 75ЊC and the second at 275ЊC were due to the residual stresses associated with the polystyrene and polyimide blocks, respectively. The third at 330ЊC was probably attributed to foam collapse. The structural instability in polyimide matrix induced by the residual stresses was believed to be the reason causing the foam collapse. To overcome such a problem, an annealing process was carried out. The annealed film showed no contraction and, moreover, no foam collapse was observed in the thermomechanical analysis.
Biobased Thermosetting Epoxy Foams: Mechanical and Thermal Characterization
ACS Sustainable Chemistry & Engineering, 2015
Thermosetting epoxy foams were synthesized by replacing the commercial synthetic epoxy resin by a biogenic epoxidized vegetable oil. Foam formulations were developed avoiding the use of amine hardeners, organic volatile compounds (OVCs), and ozone depleting or flammable foaming gases. The produced biobased foams were evaluated in terms of mechanical and thermal properties. It was found that the glass transition temperature (Tg) is somewhat lower than that corresponding to synthetic epoxy foams, but mechanical properties are similar when comparing foams of the same density. Moreover, the possibility of obtaining foams in a wide range of densities (160−550 kg/m 3) makes these systems a sound alternative to commercial available formulations.