rate constants ( /2 "= 8 s) and thus the literature values quoted in this paper should be considered lower limits to the reaction rate for the conditions employed here (1 N NaOH).Acid-Catalyzed Hydrolysis of PE-COgCHg. Hydrolysis was carried out by floating PE-C02CH3 (ester side down) on the surface of 50% (w/w) H2S04 at 25 ± 2 °C for the specified time.The film was rinsed 4 times in water and once in acetone and air dried. Literature values for the hydrolysis rate were determined from the pseudo-first-order rate constants established under identical conditions.26Registry No. polyethylene,

The preparation and characterization of a new nonmicroporous carbon to be used as a reference material with a standard N2 adsorption isotherm for characterization of activated carbons are described.

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Thermoplastic polyurethane (PU) coatings with pressure sensitive adhesion property were synthetized by reacting 4,4′-diphenylmethane diisocyanate (MDI) with 1,4-butanediol and mixtures of polypropylene glycols (PPGs) of different molecular weights (1000 and 2000 Da). Good tack at 10-37°C was obtained in PU coatings prepared with PPG2000 + PPG1000 mixtures containing 50 wt% or more PPG2000. The pressure sensitive adhesion properties of the PU coatings were related to their minor content of bonded urethane groups and important degree of phase separation. Furthermore, these PU coatings followed Dahlquistś criterium, they showed low glass transition temperatures, high tack, and low 180°peel strength. Therefore, the PU coatings had potential as pressure sensitive adhesives. Finally, PU coating made with PPG of molecular weight 1000 Da did not show pressure sensitive adhesion property.

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Three nanosilicas with different silanol contents were prepared by treatment of hydrophilic fumed silica with dimethyldichlorosilane. This treatment reduced the silanol content and produced the particle agglomeration of the nanosilicas. Thermoplastic polyurethane (TPU) adhesives containing nanosilicas were prepared and characterized by FTIR spectroscopy, differential scanning calorimetry (DSC), plate-plate rheology, dynamic mechanical thermal analysis (DMTA), transmission electron microscopy (TEM) and stress-strain testing. Adhesive strength was obtained from T-peel tests of PVC/polyurethane adhesive joints.The addition of hydrophilic nanosilicas favoured the degree of phase separation between the hard (i.e. isocyanate+chain extender) and soft (i.e. polyol) segments in the TPUs; the higher the silanol content on the surface of silica, the higher the degree of phase separation, and the crystallinity of the polyurethane (due to the soft segments) was also increased. Hydrogen bonds between the ester carbonyl groups in the TPU and the silanol groups on the silica surface were created and more favoured by increasing the silanol content. The tensile strength increased and the elongation at break of the polyurethane decreased by increasing the silanol content of the nanosilica. Addition of nanosilica increased the immediate adhesion of the polyurethane adhesives to PVC, irrespective of the silanol content on the nanosilica. The higher the mechanical and the rheological properties of the polyurethanes containing nanosilicas with different silanol content, the higher the final adhesive strength. r