Study On Rigid Polyurethane Foam Composites Modified By Organoclays

Rigid polyurethane foam (RPUF) is an important polymeric foam material because of its unique properties, such as low mass, excellent heat insulation, excellent shock absorption, relatively high specific compressive strength, the flexibility in properties that can be obtained by varying the synthesis and processing conditions, and good cohesiveness with most materials. Because of these advantages. RPUF is one of the most widely used plastics and has been used in various fields of the national economy.However, RPUF has some disadvantages, such as relatively low mechanical properties compared to structure materials, be apt to accumulate charges, easy to be burned and cause fire accident and so on. Therefore, great interests have been paid on improving the properties of RPUF. Montmorillonite is a kind of clay who has natural nanostructure. Organically modified MMT (organoclay) may act as a reinforcement agent to improve the mechanical properties of the polymer matrix, or act as a flame retardant additive to improve the thermal stability and flame retardancy of the polymer matrix.This study firstly discussed the formula and processing of RPUF using water as blowing agent, and obtained an optimal experiment project. To investigate the influence of various organically modified montmorillonites (organoclays) on the structure, mechanical properties, thermal stability and flame retardancy of RPUF composites, the organoclays modified with cetyltrimethyl ammonium bromide (CTAB), methyl tallow bis(2-hydroxyethyl) quaternary ammonium chloride (MT2ET0H) and tris(hydroxymethyl)aminomethane (THMA) and denoted as CMMT, Cloisite 30B and OMMT were used to prepare RPUF/organoclay composites. Because MT2ET0H and THMA contain hydroxyl groups, Cloisite 30B and OMMT can be partially exfoliated in the composites because their intercalating agents can react with isocyanate. However, CMMT modified with nonreactive CTAB is mainly intercalated in the RPUF matrices. At relatively low filler content, the RPUF/CMMT composite foam has a higher specific compressive strength, while at relatively high filler contents, RPUF/Cloisite 30B and RPUF/OMMT composites have higher specific compressive strengths, higher modulus and more uniform pore sizes than that of the RPUF/ CMMT composite. The addition of organoclays lead to improvement in thermal stability and fire retardancy of the RPUF matrix, and among the three RPUF/organoclay composites, RPUF/OMMT has the best flame retardancy.