Highly reinforcing and thermal stabilizing effect of imide structure on polyurethane foam

Abstract

In order to improve the heat‐resistant property of polyurethane foams, a series of polyurethane‐imide foams (PUIFs) with different contents of the imide group were fabricated via the prepolymer foaming method. It was found that the PUIFs showed a closed cellular structure with almost circular cell shapes. With increasing content of imide groups, the cell wall thickness and apparent density of the foams gradually increased, and the cell size showed a trend of first increasing and then decreasing. All foams exhibited a multistage deformation response when subjected to compressive loading, and the compressive strength and modulus of the PUIFs were significantly improved by incorporation of the imide group, increasing by roughly 5500% and 6400% for the PUIF with 34.25 wt% imide groups, indicating the remarkable reinforcing effect of the imide group on the PUIF. TGA and dynamic mechanical analysis showed that with increase of the imide group content the thermal degradation temperatures, the char yield and the degradation activation energy for the PUIFs sharply increased, while the storage modulus (G′) and Tg were obviously improved, reaching 575 MPa and 283 °C respectively, much higher than that of most reported PU foams, indicating the remarkable enhancement of the thermal mechanical stability of the PUIF. The heat insulation of the PUI system was also enhanced by the incorporation of imide groups. Such PUIFs showed potential applications for use in high temperature environments. © 2018 Society of Chemical Industry

Highly Reinforced Poly(lactic acid) Foam Fabricated by Formation of a Heat-Resistant Oriented Stereocomplex Crystalline Structure

“…The gravimetric method was applied to determine the dissolved CO 2 amount in PLLA/PDLA samples and the weight loss of saturated samples during the desorption process according to ref . The tensile properties of PLLA/PDLA foams were measured using a 4302-material testing machine (Instron Co., USA) according to ISO527/1-1993 (E), − while dynamic mechanical analysis was performed by using a DMA Q-800 (TA Instruments, USA). The relevant detailed calculation methods of the above properties of PLLA/PDLA blend samples are shown in the Supporting Information.…”

Solvent-Free Preparation of Thermally Stable Poly(urethane-imide) Elastomers

“…With the fast development of the PU market, further improvement of the chemical and physical properties of PU materials will make them meet the increasing demands on high-performance materials and suit a rising number of applications. This can be achieved by the chemical modification of PU with thermally stable chemical motifs such as aromatic polyimides, which are one of the most remarkable structures with respect to their outstanding thermal, mechanical, and electrical properties. − As aromatic polyimides have been used to enhance the thermal properties of various polymer matrices, such as poly­(ether imide)­s, poly­(ester imide)­s, and poly­(amide imide)­s, ,− the incorporation of aromatic polyimides in PU promises the development of thermoplastics, − rigid foams, − and coatings − with significantly enhanced thermal stability and flame retardancy, which is especially important for construction and automotive industries.…”

Preparation and characterization of polyurethane foams containing microencapsulated phase change materials for thermal energy storage and thermal regulation

“…6 Therefore, there is a significant requirement to improve the thermal energy storage and thermal regulation capacity of PU foams, which will further contribute to improve energy utilization efficiency and conserve energy. 7 The significant development of phase change materials (PCMs) in recent years might offer a new opportunity for the fabrication of advanced PU foams with good thermal energy storage and thermal regulation properties. 8,9 PCMs, especially organic PCMs, can absorb and release significant amounts of latent heat within a small temperature range in the process of phase change.…”

“…However, PU foams do not possess thermal energy storage and thermal regulation properties, thus seriously restricting wide application 6 . Therefore, there is a significant requirement to improve the thermal energy storage and thermal regulation capacity of PU foams, which will further contribute to improve energy utilization efficiency and conserve energy 7 …”