Study of Polyurethane Foaming Dynamics Using a Heat Flow Meter

B Zygmunt,J Zmywaczyk,M Preiskorn,M Trzyna,P Koniorczyk

doi:10.1007/s10765-017-2209-7

B Zygmunt, J Zmywaczyk + Show 3 more

Open Access

https://doi.org/10.1007/s10765-017-2209-7

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Abstract

This work presents the results of the study concerning the effects of fillers addition on the heat flux density dot{q}left( t right) of foaming of polyurethane–polystyrene porous composite (PSUR) and describes the dynamics of this process during the first 600 s. This foaming process resulted in obtaining porous materials that were based on HFC 365/225 blown rigid polyurethane foam (PUR) matrix, which contained thermoplastic expandable polystyrene (EPS) beads as the filler. In PSUR composites, the EPS beads were expanded after being heated to a temperature above the glass transition temperature of EPS and vaporing gas incorporated inside, by using the heat of exothermic reaction of polyol with isocyanate. From the start (t=0) to the end of the PSUR composite foaming process (t=t_{k}), dot{q}left( t right) was measured with the use of the heat flow meter. For the purpose of the study two PUR systems were selected: one with high and one with low heat density of foaming process q. EPS beads were selected from the same manufacturer with large and small diameter. The mass fraction of EPS in PSUR foam varied during the measurements. Additionally, a study of volume fractions of expanded EPS phase in PSUR foams as a function of mass fractions of EPS was conducted. In order to verify effects of the EPS addition on the heat flux density during PSUR foaming process, the thermal conductivity measurements were taken.

Highlights

Fillers are added to polymers in order to reduce composite cost and to improve processing behavior as well as to modify product properties [1]
As it was mentioned above, the PSUR composites were prepared in order to estimate the influence of expandable polystyrene (EPS) on q (t) and on the volume fractions of EPS phase in PSUR foams VEPS/PSUR as a function of mass fractions of EPS, i. e
The EPS was expanded by using heat from exothermic polyol and isocyanate reaction; the density of the composite filled with EPS was increasing

Summary

Introduction

Fillers are added to polymers in order to reduce composite cost and to improve processing behavior as well as to modify product properties [1]. Typical powder fillers used for preparation of rigid polyurethane foams (PUR) are aluminum hydroxide, melamine, starch, talk, chalk, borax [5], calcium carbonate, barium sulfate [6], crystallized silica [7] and nanofillers like bentonite [8] and expanded graphite [9]. It is worth mentioning at this point that the only tool to perform the verification and analysis of the heat transfer mechanism in such foams is the measurement of thermal conductivity [19,20]. Since we analyze the finished product, we can only guess what was the course of the exothermic polymerization process as a function of time and how it affected the value of the thermal conductivity of foams

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Conclusion