Effect of hard segments on the thermal and mechanical properties of water blown semi-rigid polyurethane foams

Abstract

Water blown semi-rigid polyurethane foams with different ethylene glycol (EG) content were prepared. EG is used as chain extender to vary hard segments content of semirigid polyurethane foams. The effect of EG on foam molding process, hard segment structure and the relationship between structure and thermal, mechanical properties of foams has been investigated. Results indicate that the addition of EG contributes to preparing flawless foams, and reduces the apparent density of foams due to the increase in cell size. Fourier transform infrared analysis (FTIR) displays the existence of hydrogen bonds among polyurea segments, which is influenced by reactant activity. Dynamic mechanical analysis (DMA) manifests different phase mixing and soft domains Tg of foams with different EG content. Soft domains Tg is dependent on the purity of soft domains controlled by urethane hard segments and dissolved urea groups. Thermo gravimetric analysis (TGA) illustrates that thermal stability of foams is associated with hard segments content in foams. Mechanical tests demonstrate that improvements of mechanical properties of foams can be achieved by modifying foam formulation to increase microphase separation of polyurea segments.

Preparation of microcellular thermoplastic polyurethane (TPU) foam and its tensile property

“…Figure 4a shows the expansion ratio of TPU foams as function of foaming temperature. Obviously, the TPU with a higher hard segment content generates more crystalline region, higher viscosity and higher hardness, and the corresponding expansion ratio is restricted [47,48]. The TPU-36 has the highest hard segment content generating the highest restriction for the foaming process, the TPU-32 is next, and the TPU-26 is the weakest one.…”

The Effect of Soluble Ammonium Polyphosphate on the Properties of Water Blown Semirigid Polyurethane Foams

“…In these years, however, semirigid polyurethane foam (SPUF) is generally used in various fields, such as leather processing, textile printing, paper-making industry, architectural coatings, adhesives, and cushioning materials. Some flame retardants, EG, halogencontaining flame retardant, and phosphate ester were added to SPUF to improve the fire resistance [13][14][15][16].…”

One‐pot synthesis of cobalt‐incorporated polyglycerol ester as an antimicrobial agent for polyurethane coatings

“…The blank PGE achieved a desirably low acid value of 0.34 mg of KOH/g of sample; this made it a potential polyol for PU because the unreacted acids remaining in the polyol could lead to a poor conversion rate and excessive isocyanate usage. Furthermore, the reaction between the carboxylic acid and isocyanate produced urea, which acted as a hard segment in the PU . The blank PGE possessed a high hydroxyl value of 201.17 mg of KOH/g of sample and an M w of 1471 g/mol (Table ).…”