Processing of composite polystyrene foam with a honeycomb structure

In this work, composite materials containing aramid honeycomb core (ARHC) reinforced isocyanate‐based polyimide foams (IBPIFs) were prepared by a simple free‐foaming process. The flame retardance, smoke performance, and mechanical property of the composite materials along the transverse (W) and longitude (L) directions of ARHC were studied. Results of limiting oxygen index and cone calorimeter reveal that the space partition action of ARHC on IBPIFs, barrier action of honeycomb structure on fire, and generation of straight, flurry and porous char layer in the honeycomb cells during combustion effectively enhanced the flame retardance of IBPIFs. Mechanical property test shows that IBPIFs and ARHC presented a positive synergetic effect, and ARHC increased the compression strength of IBPIFs along the W and L directions of ARHC by approximately 300%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45041.

Section: Resultsmentioning

confidence: 73%

Effects of aramid honeycomb core on the flame retardance and mechanical property for isocyanate‐based polyimide foams

Sun

Wang

et al. 2017

“…However, the limiting oxygen index of neat EPS foam is only 17%, which makes it highly flammable . The cellular and spongy structure of EPS provides a large specific surface area, and abundant toxic smoke may be released during combustion due to the existence of benzene in the molecule …”

Section: Introductionmentioning

confidence: 99%

“…3 The cellular and spongy structure of EPS provides a large specific surface area, and abundant toxic smoke may be released during combustion due to the existence of benzene in the molecule. 4 Based on the manufacturing process, flame-retardant EPS foams can be obtained by the following approaches: (1) adding flame retardant in the polymerization or impregnation stage, (2) adding a flame-retardant coating during the foaming process, (3) postprocessing. Despite the fact that adding flame retardants to styrene monomer before polymerization is regarded as a convenient method, the additive may interfere with the polymerization and cause a high concentration of residual styrene.…”

Section: Introductionmentioning

confidence: 99%

Flame‐retardant expandable polystyrene foams coated with ethanediol‐modified melamine–formaldehyde resin and microencapsulated ammonium polyphosphate

Zhang

Han

et al. 2018

Melamine–formaldehyde resin was modified by ethylene glycol to decrease the amount of free formaldehyde and extend the storage time. The modified resin (EMF) was further used to prepare microencapsulated ammonium polyphosphate (MCAPP). The structures of both EMF and MCAPP were well characterized. Afterward, EMF and MCAPP were mixed and coated on the surface of pre‐expanded polystyrene particles to prepare flame‐retardant expandable polystyrene foams (EPS). Both water resistance and impact strength were enhanced by the presence of MCAPP, and the flammability of the samples was also significantly improved. For the sample containing 75 phr MCAPP, the limiting oxygen index value was increased to 31.4% with a V‐0 rating in the UL‐94 vertical burning test. Cone calorimeter tests showed that the peak heat release rate of the sample declined sharply to 172.7 kW/m2, which is 81.6% lower than that of neat EPS. The smoke production of EPS foams during combustion was suppressed by the presence of MCAPP, and the thermal stability was also improved. Scanning electron microscopy showed that the char layer of the flame‐retardant sample after combustion became compact with negligible voids or cracks, which could further form an isolation barrier to prevent both heat and flame transfer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46471.

“…This process design was demonstrated with the capability of effectively expanding highly loaded EPS microspheres. The microwave expansion process was later extended to produce composite polystyrene foams with a unique honeycomb‐like structure . The mechanical strength and fire resistance of the composite foams were found to be considerably improved compared with those made of pristine polystyrene.…”

Section: Introductionmentioning

confidence: 99%

“…The microwave expansion process was later extended to produce composite polystyrene foams with a unique honeycomb-like structure. 9 The mechanical strength and fire resistance of the composite foams were found to be considerably improved compared with those made of pristine polystyrene. To optimize the microwave expansion process, a further understanding of the fundamental aspect of this process is highly desired.…”

Section: Introductionmentioning

confidence: 99%

Modeling of expandable polystyrene expansion

Hong

Fang

Yao

2016

Self Cite

A fundamental understanding of the expansion kinetics of expandable polystyrene (EPS) is crucial for the design and optimization of processes for EPS-filled syntactic foams. In this study, a general formulation was developed to model EPS expansion. A semi-analytical solution was obtained on the basis of the case of a single bubble expansion in an infinite matrix. The dimensionless bubble radius and pressure were defined and found to be exponential functions of the dimensionless expansion time. The characteristic bubble expansion time was able to characterize the timescale of the expansion process. The semi-analytical solution could qualitatively predict the radial expansion of the EPS microsphere observed in a real-time experiment. To obtain an accurate prediction, a numerical solution was obtained to the model that coupled the nucleation and expansion of multiple bubbles in a finite matrix at various temperatures. The results show that the numerical solution was able to quantitatively predict the radial expansion of EPS. A parameter sensitivity study was performed to examine the effect of each parameter over the expansion process. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43886.