No abstract

No abstract

No abstract

A new class of thermoplastics (dubbed "chimerics") is described that exhibits a high temperature glass transition followed by high performance elastomer properties, prior to melting. These transparent materials are comprised of cocontinuous phase-separated block copolymers. One block is an amorphous glass with a high glass transition temperature, and the second is a higher temperature phase transition block creating virtual thermoreversible cross-links. The material properties are highly influenced by phase separation on the order of 10-30 nm. At lower temperatures the polymer reflects the sum of the block copolymer properties. As the amorphous phase glass transition is exceeded, the virtual cross-links of the higher temperature second phase dominate the plastic properties, resulting in rubber-like elasticity. This article will particularly focus on plastics produced from phthalate-based polyester amorphous phases extended by urethane-derived second phases. Glass transitions from approximately 100-115 °C and subsequent elastomer phases to 150 °C are measured. The polymers exhibit high modulus (G 0 = 1 GPa), surprisingly high toughness (up to 2 times that of Bis-A polycarbonate) below the glass transition, and very high elongations and very low elastomer set subsequently. Materials are characterized by X-ray diffraction, DSC, AFM, dynamic mechanical spectroscopy, and tensile measurements. These materials may vastly simplify thermoplastic processes requiring high melt elasticity.

The flexural modulus of oak and pine boards suffused with polymeric methylene diphenyl diisocyanate (pMDI) was measured as a function of the amount of pMDI imbibed. The resulting modulus values were compared to predicted values calculated by assuming a relationship between the composite phases. Specifically, the measured flexural moduli were compared to values obtained from a Kerner model, in which the composite phase consists of isolated and spherical particulate isotropically arranged in the major phase. Results were also compared to a Davies model, in which the two phases exist in a bonded co-continuous morphology. The measured data was shown to be well fit to the Kerner model and not well described by the Davies model, despite the fact that the Davies model is more physically descriptive of the filled wood pore structure. This incongruous result indicates that the pMDI/wood interface is weak, and the resulting tensile properties are not significantly different from the wood-air composite in the absence of pMDI.