First/second generation of dendritic ester-co-aldehyde-terminated poly(amidoamine) as modifying components of melamine urea formaldehyde (MUF) adhesives: subsequent use in particleboards production

摘要

Particleboards production, which depends mainly on thermoset resins, e.g., such as melamine urea formaldehyde (MUF) and urea formaldehyde (UF), can result in subsequent liberation of the carcinogenic formaldehyde of the panel in service. This situation needs the substitution of formaldehyde with less active aldehydes. However, to date, the resins prepared from less active aldehydes suffer from markedly lower reactivity, difficult processing, short shelf-life and inferior performance after application to particleboards manufacture. The current work addresses such an issue, which is of both health and environmental concern while keeping in mind the economic aspect. It depends upon two routes of modification of MUF resins: first by using different generations of a hyperbranched ester-terminated-co-aldehyde-terminated poly(amidoamine)s, HB(PAMAM-(COOCH3)n(CHO)m), after their preparation and characterization using fourier transform infrared (FTIR), 13C nuclear magnetic resonance (NMR), and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), as reactive additives and property enhancers in the first reaction step without altering the usual ratios of the reactants as in the basic recipe. Second, the use of the additives in the first step involved a parallel systematic substitution of formaldehyde,without seriously influencing resin properties or their relevant particleboards. The upgrading of either some resins or particleboards properties was confirmed by contact angle measurements, mechanical properties as well as thermomechanical analysis (TMA). It could be suggested that HB(PAMAM-(COOCH_3)n(CHO)m) worked in the second case as a co-condensing agent rather than a bridging agent as in the first case.