Properties of rigid polyurethane foams blown by HCFC141B and distilled water

Rigid polyurethane foams (PUFs) were prepared from polymeric 4,4'-diphenylm ethane diisocyanate, polyester polyol, 1,4-butane diol, silicone surfactant , hydrochlorofluorocarbon (HCFC) 141B, and distilled water. The properties and structure of the PUFs were investigated with differential scanning calo rimetry (DSC), scanning electron microscopy (SEM), and a universal testing machine. The density of the PUF blown by distilled water and/or HCFC 141B d ecreased from 175.7 to 28.2 kg/m(3) with an increase of blowing agents. Fro m the SEM results, the average cell size of the PUF blown by distilled wate r increased from 150 to 290 mum with the distilled water content. From the DSC results, the glass-transition temperature (T-g) of the PUF blown by dis tilled water increased from 85.7 to 101.7 degreesC with increasing distille d water content, whereas the T-g of the PUF blown by HCFC 141B remained unc hanged with HCFC 141B content. The compressive strength and modulus of the PUF blown by a mixture of distilled water and HCFC 141B was increased from 0.13 to 0.25 MPa and from 3.00 to 7.23 MPa, respectively, with the distille d water content at the sample density of about 44.0 kg/m(3). The increase o f the compressive strength and modulus of the PUF at the same density was r elated to the increase of the T-g from 86.0 to 100.9 degreesC. (C) 2001 Joh n Wiley & Sons, Inc.