Cyanoacrylate table

The discrimination between wild type and mutant thylakoids shown by both the benzylamino (I) and N-methyl anilino (II) cyanoacrylates (Table 1) suggest that they, like atrazine, bind to the peptide in the wild type close to the serine2 4 residue. Likewise, the lack of discrimination shown by the thiolate salt (III) implies that it binds away from the modified amino acid region. 

Polyimides can be bonded with cyanoacrylates (Table 3.6) but the rigidity of these adhesives often resnlts in a high stress concentration at the periphery of the joint and this indnces prematnre failnre of the material (see Section 10.3.4). 

Nitrile rubber is generally easy to bond with cyanoacrylates (Table 4.8) and the use of a primer is not normally necessary. Of the other adhesives tested, the two-part acrylics and the UV acrylics showed promising adhesion. 

Table 2. Cured Bulk Properties of Common 2-Cyanoacrylic Esters...

Table 3. Adhesive Bond Properties of 2-Cyanoacrylic Esters with Metals and Various Polymeric Materials...

To prevent premature polymerization, a strong protic or a Lewis acid is added to the distilled monomer and to adhesive formulations. A wide variety of materials have been utilized as acidic stabilizers in the alkyl cyanoacrylate monomers. A list of some of these materials is shown in Table 1 [2,11-14]. 

An example of this improvement in toughness can be demonstrated by the addition of Vamac B-124, an ethylene/methyl acrylate copolymer from DuPont, to ethyl cyanoacrylate [24-26]. Three model instant adhesive formulations, a control without any polymeric additive (A), a formulation with poly(methyl methacrylate) (PMMA) (B), and a formulation with Vamac B-124 (C), are shown in Table 4. The formulation with PMMA, a thermoplastic which is added to modify viscosity, was included to determine if the addition of any polymer, not only rubbers, could improve the toughness properties of an alkyl cyanoacrylate instant adhesive. To demonstrate an improvement in toughness, the three formulations were tested for impact strength, 180° peel strength, and lapshear adhesive strength on steel specimens, before and after thermal exposure at 121°C. 

An alternative hydrophobic microparticulate dosage form can be produced using poly(alkyl cyanoacrylates) also referred to as simply poly(cyanoacrylates) (PCAs) (Table 11.3). Poly(cyanoacrylates) are a class of addition polymers that undergo polymerization under mild conditions, and even upon the addition of water or ethanol. Poly(cyanoacrylates) have been widely investigated for delivery of biomacromolecules. Due to their properties, cyanoacrylates can easily be formed into two types of particles spheres (Couvreur et al. 1982) or capsules (Al-Khouri Fallouh et al. 1986), both of which can be used to deliver biomacromolecules. The most used of the poly(cyanoacrylates) is poly (isobutyl cyanoacrylate) (PBCA). The reason... 

Ihe polymers of the 2-cyanoacrylic esters, more commonly known as the alkyl 2-cyanoacrylates, are hard glassy resins that exhibit excellent adhesion to a wide variety of materials. The polymers are spontaneously formed when their liquid precursors or monomers are placed between two closely fitting surfaces. Tile spontaneous polymerization of these very reactive liquids and the excellent adhesion properties of the cured resins combine to make these compounds a unique class of single-component, ambient-temperature-curing adhesive of great versatility (Table 3). The materials that can be bonded run the gamut from metals, plastics, most elastomers, fabrics, and woods to many ceramics. 

TABLE 3. ADHESIVE BOND PROPERTIES OF 2-CYANOACRYLIC ESTERS WITH METALS AND VARIOUS POLYMERIC MATERIALS... 

TABLE 1. Instron lap shear testing results for selected a-cyanoacrylate monomeric derivatives. 

TABLE 2. In vitro degradation and glass transition temperatnres of selected a-cyanoacrylate polymeric derivatives. 

Table 1. Properties of Common Cyanoacrylate Monomers, OOCC 2...

The bulk physical properties of tire polymers of the 2-cyanoacrylic esters appear in Table 2. All of these polymers are soluble in -nu-tlivlpvrmlidiinmi-. Y. Y-dimet 1 nil< >rni mride. and nitrornethane. The adhesive bonding properties of typical formulated adhesives are listed in Table 3. 

Results. The results in Table 6.1 are the determination of Nb complex salt added to cyanoacrylate adhesive as a tracer added at a concentration of 1.5 ig g 1 (ppm = 1500 ngg1) Nb using three non-destructive methods. The results obtained are similar to 0 % PMMA. Figure 6.1 shows the intensity of Nb in cyanoacrylate monomers with and without PMMA thickening agent. 

Method. Into clean platinum vessels accurately weigh approximately 2.0 g of each cyanoacryate adhesive listed in column 1 of Table 6.1. Into one series add 0.1 g of PTSA and in the second series no PTSA is added. Ash both samples using the conditions in Table 6.2. Figure 6.2 shows the ramping and hold stages for ashing cyanoacrylate adhesives. 

Table 6.3 Program for microwave acid digestion of cyanoacrylate adhesives using ramping and holding stages ...

Results of analysis of cyanoacrylate adhesives listed in column 1 of Table 6.1 using the three destructive methods are given in Table 6.4. 

Table 6.4 Results of comparison of destructive sample preparation methods for the determination of the concentration of Nb in cyanoacrylate adhesive, in /ig/mlippm)...

Method. An accurate weight of approximately 2.0 to 3.0 g of each polyurethane listed in Table 6.24 is placed in a clean platinum dish with 0.15 g of PTSA. The samples are ashed using a program of ramping/holding stages similar to methods described for cyanoacrylate adhesives to a maximum temperature of 650 °C. The resulting ashes are contacted with 10.0 ml of 0.1 M HC1 and the suspensions transferred to a Teflon beaker. To each add 2.0 ml of cone. HF and heat to -150 °C on a hot plate to dissolve the SiC>2. The clear solutions are made up to mark in a plastic volumetric flask with deionised water. 

To a deep red-violet colored solution containing 1-phenyldiazoethane (5.5 g, 0.042 mol) was added a solution of methyl ( )-3-aryl-2-cyanoacrylate (0.03 mol) in CH2CI2 (25 mL) at — 5 to 0°C. The deep color of the diazo compound disappeared gradually and became light yellow. After the mixture stood overnight at rt, the solvent was evaporated under reduced pressure (20-25 Torr) at 40-50"C, and 12-15 g of crude product was obtained. The products were separated by chromatography on silica gel with a mixture of CHCI3 and CC as eluant. The isolated products that were solids were recrystallized from 95% EtOH or from benzene. Other similar examples are compiled in Table 4. 

Any bond strength achieved with ethyl 2-cyanoacrylates rapidly decreased on prolonged water storage with nearly complete destruction of the bond occurring within thirty days (Table I). 

The physical properties of the monomers must be discussed along with those of the cured polymers because consideration of one without the other presents an incomplete picture. The 2-cyanoacrylic ester monomers are all thin, water-dear liquids with viscosities of 1 3 mPa-s(=cP). Although a number of the esters have been prepared and characterized, only a relative few are of any significant commercial interest, and, of those, the methyl and ethyl esters by far predominate. The physical properties of the principal monomers are induded in Table 1. 

The data presented in Table 1 compare the heat resistance of allyl cyanoacrylate and methyl cyanoacrylate determined by heating a steel lap shear specimen for 1 week... 

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