XPS Foam Research Articles

Discussion on the product model technology of XPS foam plastic

Discussion on the product model technology of XPS foam plastic

Blast Performance of Polyurea-Coated Modular Structure Composed of Fiber-Reinforced Polymer and Foam Sandwich Panels

Lightweight modular structures have become a requirement in today’s world, especially for areas that are prone to occurrence of extreme events, such as earthquakes and blasts, and are situated in difficult terrains with challenging accessibility. Sandwiched composites can be one of the most suitable building units for construction of these structures due to their engineered mechanical and physical properties. Therefore, in this numerical study, performance assessment of a sandwich modular structure in the shape of a truncated cylinder is conducted under blast load. The sandwich modular structure is composed of flat and curved carbon fiber-reinforced polymer (CFRP) and extruded polystyrene (XPS) foam sandwich panels. A three-dimensional (3D) finite element (FE) model of the sandwich modular structure is developed considering the orthotropic behavior of CFRP facesheets and the crushing foam behavior is accounted for the XPS foam core in the FE modeling. The damage assessment in the CFRP facesheet is performed using Hashin’s damage criterion. Furthermore, the effect of polyurea with varying thicknesses on the blast-resistance of the structure is investigated. The polyurea is modeled as hyperelastic material using the Mooney-Rivlin model. The influence of polyurea positioning is studied when (a) applied externally to flat and curved walls of the structure directly exposed to the blast and (b) applied internally to flat and curved walls of the structure opposite to the exposure of the blast (rear face). It is observed that the flat walls of the structure are more vulnerable to the blast load than the curved walls of the structure. Moreover, a quadratic and linear reduction in the deflection of flat and curved walls with increasing thickness of polyurea coating is obtained, respectively. In addition, with increasing thickness of the additional polyurea coating, a logarithmic reduction in the kinetic energy of the sandwich modular structure is reported.

Changes in HCFC emissions from foam sector in eastern China from 2000-2019

Hydrochlorofluorocarbons (HCFCs) are greenhouse gases and ozone-depleting substances, and existing HCFC emission studies lack a comprehensive study of multiple HCFCs in a single consumption sector. China is a large producer and consumer of HCFCs. The HCFC bank in foam sector in 2019 accounted for 91.3% of the national total, and foam sector was also the second largest source of HCFC emissions. Therefore, the estimation of HCFC emissions and banks for the foam sector is quite important. In this study, the multiple HCFC emission inventory for foam sector in eastern China from 2000 to 2019 was first established by using the bottom-up method. The results showed that the HCFC emissions and bank were 14.9 kt and 453.5 kt in 2019. HCFC-141b used in the polyurethane (PU) foam sector had the largest annual emissions, cumulative emissions, and bank due to its high consumption. The total emissions of HCFC-22 and HCFC-142b used in the extruded polystyrene (XPS) foam sector were similar to those of HCFC-141b. The HCFC emissions from the foam sector were mainly distributed among the three provinces of Jiangsu, Zhejiang, and Shandong. The cumulative GWP- and ODP-weighted emissions of HCFCs were 240.6 Mt CO2-eq and 14.3 kt CFC-11-eq, respectively. The results showed that in order to response to climate change or ozone depletion, we should prioritize the emission reduction of HCFC-22 and XPS foam sector, or HCFC-141b and PU foam sector.

A Simulation-Free Replacement Solution for Radiation Therapy Immobilization Devices Using Computer Numerical Control (CNC) -Milled Polystyrene Molds

In radiation therapy (RT), if an immobilization device is lost or damaged, the patient may need to be brought back for resimulation, device fabrication, and treatment planning, causing additional imaging radiation exposure, inconvenience, cost, and delay. We describe a simulation-free method for replacing lost or damaged RT immobilization devices. Replacement immobilization devices were fabricated using existing simulation scans as design templates by computer numerical control (CNC) milling of molds made from extruded polystyrene (XPS). XPS material attenuation and bolusing properties were evaluated, a standard workflow was established, and 12 patients were treated. Setup reproducibility was analyzed postfacto using Dice similarity coefficient (DSC) and mean distance to agreement (MDA) calculations comparing onboard treatment imaging with computed tomography (CT) simulations. Results showed that XPS foam material had less dosimetric impact (attenuation and bolusing) than materials used for our standard immobilization devices. The average direct cost to produce each replacement mold was $242.17, compared with over $2000 for standard resimulation. Hands-on time to manufacture was 86.3 minutes, whereas molds were delivered in as little as 4 hours and mostly within 24 hours, compared with a week or more required for standard resimulation. Each mold was optically scanned after production and was measured to be within 2-mm tolerance (pointwise displacement) of design input. All patients were successfully treated using the CNC-milled foam mold replacements, and pretreatment imaging verified satisfactory clinical setup reproduction for each case. The external body contours from the setup cone beam CT and the original CT simulation with matching superior-inferior extent were compared by calculating the DSC and MDA. DSC average was 0.966 (SD, 0.011), and MDA average was 2.694 mm (SD, 0.986). CNC milling of XPS foam is a quicker and more convenient solution than traditional resimulation for replacing lost or damaged RT immobilization devices. Satisfactory patient immobilization, low dosimetric impact compared with standard immobilization devices, and strong correlation of onboard contours with CT simulations are shown. We share our clinical experience, workflow, and manufacturing guide to help other clinicians who may want to adopt this solution.

Force attenuation performance in sandwich structures with STF and M-STF encapsulation

In this study, we investigate the role of adding shear thickening fluids (STFs) and multi-functional shear thickening fluids (M-STFs) to the core of a sandwich-structured composite made of aluminum facesheets and XPS foam cores with different geometries on force attenuation performance. Six different core designs were machined, and all designs had the same space for adding STFs and M-STFs. STF with 40 wt% SiO2 in PEG 400 was selected and fabricated. M-STFs were made by adding multi-walled carbon nanotubes (MWCNTs) up to 1.5 wt%. The effects of MWCNTs on the rheological and electrical properties of the STF were investigated. The force attenuation tests were performed with an impact drop tower test system at three different heights with 5, 10, and 15 J energy levels. According to the results, V6_STF (with 16 holes with a diameter of 6 mm) and H6_STF (with 16 rectangular cubic column with cross-sections of 6 × 6 mm) designed sandwich structures showed better performance in terms of force attenuation compared with the other samples. Next, these two sandwich structures were filled again with M-STF (0.5 wt% MWCNT), and the force attenuation performance of the structures showed an improvement further, and the H6_STF_CNT sample improved by 24.8% compared to the clean sandwich structure sample. These results demonstrate the potential of STFs and M-STFs in strengthening the force attenuation performance of sandwich structures with XPS foam cores, mainly when used with appropriate core geometry.

Low-fidelity design optimization and development of a VTOL swarm UAV with an open-source framework

Hybrid configurations in aircraft design are highly favorable as they can achieve the appropriate trade-offs required to develop a generalized unmanned aerial system (UAS). Rapid prototyping of such systems at the student level is challenging because commercial software is expensive and difficult to interlink with other tools for creating a multi-disciplinary design. We address this challenge by conceptualizing an aircraft design framework made entirely of open-source software, libraries, and in-house code. We then use this framework to design an all-electric unmanned aerial system with transitioning Vertical Take-off and Landing (VTOL) and Fixed-Wing (FW) modes. The UAV is capable of long-range surveillance up to 100 Kilometers and carrying a maximum relief payload of 1 kg while operating in an ad-hoc wi-fi network with a swarm of similar UAVs. A low fidelity particle swarm optimization algorithm (PSO) and a comprehensive propulsion architecture is also incorporated and validated against commercial software. To validate the design, a prototype is fabricated from glass-fiber and XPS foam, integrated with appropriate sensors and tuned using ArduPilot software. The results show that low-fidelity design is a safe starting point for prototyping under constrained timelines. The study is concluded by discussing the technical challenges of using free software, and some practical considerations while flight testing a UAV with a hybrid configuration.

Experimental study on thermal structure inside flame front with a melting layer for downward flame spread of XPS foam.

Thermal structure inside flame front during downward flame spread was experimentally measured for XPS foam with thicknesses of 1.6, 2.4, 3.4, and 4.4 cm. The temperature distribution and temperature gradient in the condensed phase, as well as the shape of the molten liquid, were obtained by 2-D heat transfer equations and experimental measurement. The results show that both the temperature and its temperature gradient decrease from the sample surface to the inside of the condensed phase, which results in the inclination of the melting interface. The molten layer is the thinnest near the sample surface and thicker inside the condensed phase. The adhering of the molten liquid to the wall greatly increases the thickness of the molten layer near the back wall, and the higher the thickness, the more molten material adheres to the wall. Finally, there is a relatively flat solid-liquid interface near the sample surface and a large inclined solid-liquid interface near the back of the sample, especially for the thicker samples of 3.4cm and 4.4cm. It is indicated that the distribution of the molten layer in the direction perpendicular to the plane of the XPS sheet is a significant factor for dripping and collapsing.

Fire hazard evaluation of activated carbons

Activated carbons are widely used in the iodine adsorbers in nuclear plants, but little information about their combustibility is available for fire engineers. Series of TGA experiments were conducted for activated carbons, charcoal and XPS foam. The results show that the activated carbons oxidize strongly in air atmosphere but little in N2 atmosphere. The calculated activation energies of the wood AC, anthracite AC and coconut shell AC are, respectively, 100.56, 96.34 and 91.00 kJ mol−1, which are larger than that of the XPS foam, 55.95 kJ mol−1. However, the calculated activation energies of impregnated coconut shell activated carbon is 48.60 kJ mol−1, which is smaller than that of XPS foam. A new parameter, A12, is introduced to describe the amount of evaporative mass fraction during the fast pyrolysis stage. Additionally, the (Tp, DTGp) map and quarter division method is introduced to compare fire hazard of different materials. Finally, a quantitative fire hazard evaluation model is developed based on four important parameters: E, DTGp, Tp and A12. The calculated Relative Fire Safety Factors by this model for wood AC, anthracite AC, coconut shell AC, impregnated coconut shell activated carbon, charcoal and XPS foam are 1.49, 1.91, 1.51, 1.37 and 1.0, respectively.

A New Water Level Measurement Method Combining Infrared Sensors and Floats for Applications on Laboratory Scale Channel under Unsteady Flow Regime.

In this paper, we studied water transport under an unsteady flow regime in an experimental channel (4 m in length; 3 cm in width). Our experiments implicated some measuring requirements, specifically, a water level (WL) detection technique that is able to measure WL in a range of 2 cm with a precision of 1 mm. The existing WL detection techniques could not meet our measurement requirements. Therefore, we propose a new measurement method that combines two approaches: An “old” water contact technique (float) with a “new” remote non-contact technique (infrared sensor). We used an extruded polystyrene (XPS Foam) that needed some adequate treatment before using it as float in experimental measurements. The combination of IR-sensors with treated float foam lead to a sensitive measurement method that is able to detect flat and sharp flow signals, as well as highly dynamic variations of water surface level. Based on the experimental measurements of WL and outflow at the channel output, we deduced a loop rating curve that is suitable with a power law adjustment. The new measurement method could be extended to larger scale applications like rivers and more complicated cross section geometry of irregular shape.

Chemical Recycling of Polystyrene with Tertiary Amine Switchable Hydrophilicity Solvents

Nearly 40 metric tonnes of expanded polystyrene (XPS) waste is collected through Kingston’s curbside recycling program annually before being outsourced to companies with the means to recycle it. However, transporting XPS foam products is not economically viable. Therefore, a significant challenge is finding an efficient way to reduce the volume of the XPS foam prior to transportation since it has a very low density, consisting of up to 98% air. Currently, XPS products are compacted physically which requires the use of expensive compactors and energy-intensive compression processes. In 2011, Jessop et al. demonstrated that N,N-dimethylcyclohexylamine (DMCHA), a solvent with relatively low toxicity and volatility, can be used to recycle XPS using a greener approach. DMCHA is relatively hydrophobic under neutral conditions (e.g., in water), but becomes more hydrophilic when exposed to carbonated water (CO2 dissolves in water, forming carbonic acid which protonates the DMCHA). I have worked on optimizing this process via the following steps. Firstly, the XPS is dissolved in a small volume of DMCHA in its hydrophobic, neutral form. Then, the PS-DMCHA mixture is added to carbonated water causing the DMCHA to become hydrophilic and to dissolve in the aqueous solution, resulting in a layer of PS on the surface. The PS can then be easily collected and air-dried. By adding a 30 wt.% PS/DMCHA solution to carbonated water at 60oC, I have been able to achieve a typical purity of 95 wt.% of the final XPS (i.e., 5 wt% of DMCHA remains in the XPS), determined by 1H NMR.

Melting and Dripping Flow Behaviors on the Downward Flame Spread of a Wide XPS Foam

The XPS foam is an economical and popular material for building insulation. The fire hazard of the polymer foams is a big threat due to their fast burning with melting, dripping and flowing. The objective of this work is to investigate the complicated downward flame spread characteristics of a wide polymer foam. An image division and calculation method is used to analyze the dynamic downward movement of the irregular flame leading curves based on the experiments. The results show that the lagged sub-flames might suddenly spread downward fast and catch up the neighboring flames. And the increasing of the flame spread velocity and flame height illustrate the acceleration of the downward burning, which is induced by the dripping and accumulating of liquid fuel. Additionally, the local peaks of the flame spread velocity arrive later than the flame height for both overall flame and detailed sub-flames. The flame height increases in the stage of liquid fuel accumulation but decreased in the dripping stage. The dripping of liquid fuel results in the increasing of the flame spread velocity and decreasing of the flame height. The results also show that the relationship between the non-dimensional local peak sub-flame flow velocities and the corresponding non-dimensional peak sub-flame heights can be well described with a power function, which indicates that the introduction of the small sub-flames is effective to model the complicated downward flame spread behaviors of XPS foams with stochastic dripping. Finally, most of the delay times of local peak sub-flame velocities here are in the range of [15 s, 25 s].

Quasi-static behaviour of crash components with steel skins and polymer foam cores

Different types of crash components are extensively used by the automotive industry to absorb energy during car accidents. Such components typically consist of sandwich structures with thin metal or composite plates as skins and a cellular foam as core to dissipate the energy. In this study, the quasi-static behaviour of two types of polymeric foams with different densities, namely extruded polystyrene (XPS) and expanded polypropylene (EPP), utilized as core material in a crash component, has been investigated. First, an extensive material test program involving compression tests on cubic specimens loaded in different material directions was carried out to reveal the mechanical properties of the foams. Second, quasi-static impact tests were conducted on various target configurations consisting of 0.8 mm thick skins of Docol 600DL steel and the various foam materials as core. In these tests, the applied force and the displacement of the striker were registered by the test machine, while digital cameras and 3D-DIC were used to measure the back-plate out-of-plane displacement of the various components. It seems clear from the presented results that if low weight combined with maximum energy absorption are the primary interests, an XPS foam as core seems to be beneficial, while if force reduction and minimum back-plate displacement are most important, an EPP foam as core seems to be a better choice. Thus, the response of the crash component is largely determined by the properties of the core material during quasi-static loading.

Flexural properties of sandwich composite laminates reinforced with glass and carbon Z-pins

This study aims to enhance the flexural properties of sandwich composites made from glass or carbon face and glass and carbon fibre Z-pin inserted extruted-polystyrene (XPS) foam cores. Carbon and glass pins were placed through XPS foams with two different column and row densities (15 and 30 mm). Results indicated that flexural loads, strength and modulus of glass/XPS and carbon/XPS sandwich composites significantly increased after inserting of glass and carbon rods. Core shear strengths and facing stresses of glass/XPS and carbon/XPS increased by increasing of carbon or glass rod densities. The rod type, rod density and face type of the sandwich composites are considered as significant parameters which affect the flexural behaviour of sandwich composites while using carbon rods enhanced flexural properties more than that of using glass rods due to better interfacial bonding.

Experimental and theoretical research on the fire safety of a building insulation material via the ignition process study

A series of experiments were carried out on extruded polystyrene (XPS) foam using a vertical thermal radiator. Measurements were taken for the ignition time, the pyrolysis mass and the temperature distribution. Two kinds of XPS foam with flame retardant levels of B1 and B2 were tested in the experiments and the incident heat fluxes were set as 20, 30, 35, 40, 50 and 60 kW/m2. For the XPS shrinks to a thin layer under the thermal radiator heating, thus the classical ignition theory may be improper and the new functions relationship between the ignition time and the radiant heat flux was derived in theory and experiment. What's more, the pyrolysis mass increases with the radiant heat flux, while the extent of increasing reduces as the radiant heat flux increases. And the result of temperature distribution indicated that under high incident heat flux the flame retardant treatment becomes less effective. The research results were useful for the theory and the experimental study on the fire characteristic of foamed polymer under vertical radiation condition.

Trace analyses of flame-retardant in pyrolysis of XPS foams and its revelation for flame-retardant optimization

The objective of this work is to study the detailed effects of flame-retardant on the pyrolysis behaviors of XPS foams. Thermogravimetric experiments are conducted in air atmosphere for flame-retardant and three XPS foams at different heating rates. The results show that the DTG peak of flame-retardant is higher at much lower temperatures than that of the flame-retardant foams and non-retardant one. It surprisingly suggests that the DTG peak of B2-retardant XPS foam is higher than that of B1-retardant one although more flame-retardant has been added into B1-retardant sample during manufacturing. The detailed DTG curves in local temperature ranges (260–360 °C) explain the non-monotonic effects of flame-retardant mass fraction on the pyrolysis behaviors of XPS foams. It is also reminded that the DTG peaks information is not always enough in analyzing the pyrolysis of flame-retardant materials in research and development. Detailed DTG curves in specific temperature ranges might reveal some more important technical and even philosophical principles. Finally, a proper difference between the temperatures for DTG peaks of flame-retardant and the polymers can be one of the key parameters in searching for new flame-retardants for various polymers.

Effect of Styrofoam Waste Feeds on the Growth, Development and Fecundity of Mealworms (Tenebrio molitor)

It has been reported that Styrofoam can be biodegraded by Tenebrio molitor beetle larvae within a retention time of less than 24 h and the larvae fed solely with Styrofoam able to survive for more than a month. The question is whether Styrofoam can be used as an economical feed in the cultivation of mealworms? To determine productivity effect of Styrofoam feeds on mealworms, the larvae (n = 120) were grouped into three. Group 1, 2 and 3 were cosecutively fed with yeasts (as the standard diet), Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS) were used. The observations take place in two stages. At stage 1, measurements were made on percent survival of the caterpillar, larval weight, prepupal periods, pupation periods, pupal weight and imago weight. At stage 2, the imago emerged from the pupae were separated between males and females and then mated. The number of eggs laid by the imago females in ten days are noted. The results showed, in comparison to the standard diet, EPS and XPS foam feeds did not give a significant effect on the mortality of the larvae. Both types of Styrofoam promote a significant longer periods of prepupal and pupation and significantly reduce number of eggs. Compared with yeasts and EPS foam, only XPS showed a lower weight of larvae, pupae and imago. It is inferred that the Styrofoam is not worthy as economical feeds in mealworms cultivation. However, given that Styrofoam feeds can maintain the insects life and produce eggs, the use of mealworms in polystyrene foam waste degradation is still worth considering.

Experimental investigation on downward flame spread over rigid polyurethane and extruded polystyrene foams

With the development of social economy and architectural aesthetics, flame spread over exterior thermal insulation system in real high-rise building fire disasters often features inclined downward or upward propagation, however most developed models for flame behavior prediction only assume absolute vertical or horizontal direction. Some researchers have explored the behavior of inclined upward flame spread for its quick development and hazardous characteristics. However, for downward flame spread over plastic polymers, theirs flame spread characteristics can also feature a special hazardous configuration, especially for porous and thermoplastic polymers. In this study, the orientation effects during inclined downward flame spread processes were thoroughly investigated by experimental and theoretical methods. Two kinds of typical thermal insulation materials were selected, rigid polyurethane (RPU) and extruded polystyrene (XPS) foams. The mass flow rate and flame spread rate at different inclination angles were obtained and analyzed. The different flame spread behaviors of RPU and XPS foams were scrutinized. Experimental results show that a linear relationship exists between flame spread rate and cube root of sine of sample inclination angle of RPU and XPS foams when the slope is smaller than a transition angle. The mechanism of orientation effect during the flame spread process was qualitatively analyzed in detail, and simplified expressions of flame spread rate of the two insulation materials with different orientations were deduced. The results of this study have implications concerning the fire safety design of exterior thermal insulation wall.

Effects of building concave structure on flame spread over extruded polystyrene thermal insulation material

Extruded polystyrene (XPS) thermal insulation material is widely installed on building exterior wall for energy saving, and the concave structure is a typical structure of building facade in architectural design. In this paper, both experimental methods and theoretical analysis are employed to investigate effects of concave structure on flame spread behaviors of XPS foam. Firstly, the upward flame spread tests are conducted. Significant fluctuation of the XPS flame front is observed while the movement of the pyrolysis front is relatively stable. The concave structure promotes the upward flame spread of XPS. The flame spread rate increases by 0.37 folds with the rising of concave structure factor (П) from 0 to 1.6. The growth rate of flame spread rate is 27.76% for П from 0 to 0.8, while it is merely 7.33% with П rising from 0.8 to 1.6. Reduced influence of the increase in the concave structure factor on the flame spread rate is deduced. The mechanism of concave structure effect is revealed. Moreover, a prediction model that evaluates the influence of the concave structure on flame spread characteristics of XPS is established. The predicted results are consistent with the experimental ones. The results of this work contribute to the fire hazard assessment of XPS and fire safety design of concave building facade.

Investigating the Role of Helmet Layers in Reducing the Stress Applied During Head Injury Using FEM

Background: Motorcycle accidents and sport accidents lead yearly to many head injuries like head fractures and concussion. So finding the most proper helmet for reducing the injuries to head can be very helpful for head protection in such cases. Methods: After 3D modeling of the helmet and head and meshing the model, a compressive impacting load of 1.31MPa was exerted on head and the model was analyzed using FEM. The helmet was considered as a two-layered helmet composing of an inner and an outer layer. Skull and CSF were considered as external layers of head. The analysis was repeated for a helmet with an inner layer made of extruded polystyrene (XPS), a helmet with an inner layer of expanded polystyrene (EPS) and finally a helmet with two internal layers of XPS and EPS. Results: The amounts of maximum displacement of the outer layer in the helmet with a XPS inner layer, the helmet with an EPS inner layer and the helmet with two internal layers were 2.82, 3.15 and 2.98mm, respectively and the respective amounts of stress were 32.05, 43.38 and 34.3MPa. The amounts of maximum stress in the inner and outer layer of the helmet with a XPS inner layer were respectively 16.4% and 6.6% less than those in the helmet with two internal layers. Discussion: Since the helmet with a XPS inner layer reduces the stress more than the helmet with two internal layers, it is the most optimal model for mitigating the head injury due to an impacting load. It should be noted that for simplifying the models, the dura was modeled together with the skull and the thicknesses of the XPS and EPS foam layers were considered to be equal.

A quantitative model and the experimental evaluation of the liquid fuel layer for the downward flame spread of XPS foam

The objective of this work is to investigate the distinctive mechanisms of downward flame spread for XPS foam. It was physically considered as a moving down of narrow pool fire instead of downward surface flame spread for normal solids. A method was developed to quantitatively analyze the accumulated liquid fuel based on the experimental measurement of locations of flame tips and burning rates. The results surprisingly showed that about 80% of the generated hot liquid fuel remained in the pool fire during a certain period. Most of the consumed solid XPS foam didn’t really burn away but transformed as the liquid fuel in the downward moving pool fire, which might be an important promotion for the fast fire development. The results also indicated that the dripping propensity of the hot liquid fuel depends on the total amount of the hot liquid accumulated in the pool fire. The leading point of the flame front curve might be the breach of the accumulated hot liquid fuel if it is enough for dripping. Finally, it is suggested that horizontal noncombustible barriers for preventing the accumulation and dripping of liquid fuel are helpful for vertical confining of XPS fire.