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Dynamic mechanical properties of some polyurethane‐acrylic copolymer interpenetrating polymer networks
Author(s) -
Fox R. B.,
Bitner J. L.,
Hinkley J. A.,
Carter W.
Publication year - 1985
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760250303
Subject(s) - materials science , polyurethane , copolymer , swelling , polymer chemistry , elastomer , polymer , rubber elasticity , methacrylate , phase (matter) , polymerization , chemical engineering , composite material , organic chemistry , chemistry , engineering
Dynamic mechanical properties have been investigated for interpenetrating‐network systems based on polyol‐cured polyurethanes (PU) and 2 to 1 n‐butyl acrylate‐n‐butyl methacrylate (Ac) networks. The systems were formed simultaneously (SIN) from all of the precursors and reactants for both networks in the same vessel, and sequentially (SIPN) by swelling a precured PU with the reactants that will form the Ac network. If the Ac network is formed after gelation of the PU, the IPNs are transparent and appear to have single T (tan δ max ) between those of the homonetworks; visible‐phase separation occurs if the Ac is intentionally polymerized prior to PU gelation. Damping curves were lower and broader and the T (tan δ max ) and rubber moduli were higher for the SIN than for the SIPN systems. Up to 65 percent Ac, the T (tan δ max ) data for both SIN and SIPN fit the Gordon‐Taylor equation if a T (tan δ max ) for the Ac homonetwork 7°C higher than observed is used, suggesting a higher crosslink density for the Ac network under these conditions. The differences in properties of the SIN and SIPN are assumed to be dependent on sample homogeneity and upon the presence of a tin catalyst in the SIN preparation. This can result in limited Ac‐network formation and consequent phase separation before PU gelation has occurred, and the catalyst may also increase the extent of interaction, such as grafting or hydrogen‐bond formation between the networks.