DBTDL

Dibasic acid monomers, 59 Dibasic acid poly esterifications, 17 Dibromo derivatives, 82 Dibutyltin dilaurate (DBTDL), 232 Dicarboxylic acid monomers, volatilization of, 72... 

Triethylenediamine (DABCO) and dibutyltin dilaurate (DBTDL) have been used as catalysts with concentrations of 0.25 and 0.06Z (w/w) on binder, respectively. 

Figure 5. Isocyanate decrease during curing of an un-plgmented paint at 50Z R.H. (24 C). a uncatalyzed b DABCO c DBTDL...

Figure 7. Carbon dioxide diffusion from a paint film saturated with carbon dioxide (catalyst DBTDL).

Low level wastes (LLW), 23 592. See also Low-level radioactive waste (LLW) from reactors, 77 598 Low-melting lead alloys, 14 779 Low-melting-point indium alloys, 14 196 Low-melting thiodiols, DBTDL-catalyzed step-growth solution and melt polymerization reaction of, 23 744 Low-methoxyl pectins (LM pectins), 4 728 13 69... 

Figures 20.13 and 20.14 describe the effect of dibutyltin dilaurate (DBTDL) on the tensile strength and tensile modulus for the 25/75 LCP/PEN blend fibers at draw ratios of 10 and 20 [13]. As expected, the addition of DBTDL slightly enhances the mechanical properties of the blends up to ca. 500 ppm of DBTDL. The optimum quantity of DBTDL seems to be about 500 ppm at a draw ratio of 20. However, the mechanical properties deteriorate when the concentration of catalyst exceeds this optimum level. From the previous relationships between the rheological properties and the mechanical properties, it can be discerned that the interfacial adhesion and the compatibility between the two phases, PEN and LCP, were enhanced. Hence, DBTDL can be used as a catalyst to achieve reactive compatibility in this blend system. This suggests the possibility of improving the interfacial adhesion between the immiscible polymer blends containing the LCP by reactive extrusion processing with a very short residence time.

Spindler and Frechet used 3,5-bis((benzoxy-carbonyl)imino)benzyl alcohol which decomposed thermally in THF solution containing DBTDL as a catalyst [97]. The resulting polymer was found to be insoluble unless an end-capping alcohol was added from the beginning. The end-capping groups determined the properties of the polymers such as glass transition temperature, thermal stability, and solubility. 

Synthesis of PBHI. The procedure was the same as in the synthesis of PBHI except 499g of PBHC, 155g of lEM, l.31g of DBTDL and 0.155g of hydroquinone were used. 

Linear GAP has a functionality of 2 and in order to achieve the desired level of mechanical properties, it must be raised by the addition of triols or crosslinked with triisocyanates to generate the desired extended polymeric matrix. Gas evolution is a serious problem during the curing of liquid GAP with isocyanates which react with moisture to give carbon dioxide. This carbon dioxide (C02) remains trapped in the voids of the crosslinked binder networks and results in decreased mechanical properties and performance. Some orga-nometallic compounds such as dibutyltin dilaurate (DBTDL) and triphenyl bismuth (TPB) are reported to suppress C02 formation and at the same time, accelerate the curing process [114]. 

Type Solid (%) Solvent Catalyst (DBTDL) Tack-free time n (mPa.s) Curing conditions... 

As an example, the temperature rise for the formation of a polyurethane by reaction of a polymethylenpolyphenyl isocyanate (average functionality = 2.7), with a polyfunctional polyol based on sorbitol, using dibutyltin dilaurate (DBTDL) as a catalyst, is shown in Fig. 5.19 for two different catalyst concentrations (Marciano et al., 1982). 

Figure 5.19 Experimental and adiabatic temperature rise curves for the synthesis of a polyurethane with two different catalyst amounts. Run 1, dibu-tyltin dilaurate (DBTDL) = 2.17 mol m-3 run 2, DBTDL = 6.22 mol m 3. (Reprinted from Marciano et at., 1982, Copyright 2001, with permission from Elsevier Science)...

FIGURE 16.21 (See color insert following page 530.) FTIR of DBTDL lateral gradient topcoat sample taken between 4 and 5 h after spraying. 

First, PDMS network was combined to a cellulose acetate butyrate (CAB) network into an IPN architecture in order to improve the thermomechanical properties of PDMS network (Scheme 1). The linear CAB can be cross-linked through its free OH groups with a Desmodur N3300 pluri-isocyanate. The alcohol/isocyanate reaction is catalyzed by DBTDL leading to urethane cross-links. Simultaneously, PDMS oligomers must be cross-linked independently in order to form the PDMS network. In order to carry out independent cross-linking reactions. 

Otherwise a co-network would have been obtained. Thus PDMS network was formed starting from a,co-(3-hydroxypropyl)polydimethylsiloxane (diOH-PDMS oligomer) by DBTDL catalyzed addition between the hydroxy end groups and an pluri-isocyanate cross-linker (Scheme 2). No side reaction has been detected between these precursors. 

Feng and Waldman used 4,4 -diphenylmethane diisocyanate. The polyol is either 2000 or 4000 molecular weight polypropylene glycol (PPG) and the catalyst is dibutylin dilaurate (DBTOL). The NOC-terminated urethane prepolymers are made in the usual way by reacting an excess of methane diisocyanate with PPG in the presence of DBTDL at an NCO OH ratio of 1.4 2.0. The reactions are run at 70°C for about 3 h to reach a constant percentage of NCO. 

Stannous octoate (esp. for flexible foams) dibutyltin dilaurate (DBTDL) (esp. for rigid foams) tin mercaptides, such as dioctyltin mercaptides... 

Figure 2. Dynamic mechanical properties for the M-B-23/25-48 series as a function of catalyst concentration. %DBTDL x 1000 , 05 , 30 , 75.

Molecular Weight Determination. As mentioned earlier, the GPC results for our samples are based on a polystyrene calibration curve. As such, all numbers must be regarded on a rel ati va basis. PS based weight average molecular weights, Mw, were about 10b for highly reacted samples. Actual Mw values may be lower even by a factor of 2, based on calculations for an stepwise polycondensation with 99% conversion (18). Mw versus DBTDL concentrations for a typical series are shown inTigure 13. As observed the effect of a hotter mold wall... 

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