Melting polyamides

These opposing tendencies may defeat the purpose of the fractional precipitation process. The fractional precipitation of crystalline polymers such as nitrocellulose, cellulose acetate, high-melting polyamides, and polyvinylidene chloride consequently is notoriously inefficient, unless conditions are so chosen as to avoid the separation of the polymer in semicrystalline form. Intermediate fractions removed in the course of fractional precipitation may even exceed in molecular weight those removed earlier. Separation by fractional extraction should be more appropriate for crystalline polymers inasmuch as both equilibrium solubility and rate of solution favor dissolution of the components of lowest molecular weight remaining in the sample. 

In this way one can prepare successfully even high-molecular-weight, very high-melting polyamides that are obtainable by the usual methods only in low molecular weights, if at all. Furthermore, reactants can be used that still carry... 

Just as the products of polycondensation are greatly varied, so are the reaction conditions used in their production. Some are produced in the melt (many polyamides and polyesters), some initially in the melt but with extensive polymerization continuing in the solid state (polyurethane foams and elastomers), in solution (some polyurethane fibres) or in non-homogeneous liquid systems (some polycarbonates, very high melting polyamides). 

Polyetherimide A wide variety of commercially available adhesives can be used in bonding polyetherimide to itself or to dissimilar materials. Among these are polyurethane [(cure at RT to 302°F (150°C)], RTV silicones, hot melts (polyamide types) curing at 401 C (205°C) and epoxies (non-amine type, two-part) (12). 

Reaction of Acid Chlorides. Low-temperature polycondensation of diamines and diacid chlorides is an important route for preparing high-melting polyamides such as aromatic polyamides, which decompose or cross-link if prepared by high-temperature melt routes. The reaction may involve an interfacial reaction between the diacid chloride in a water-immiscible solvent with an aqueous diamine solution, or the reaction may be carried out in a homogeneous solution. The presence of a base is usually needed to remove HCl so that polymerization is complete. With weakly basic aromatic diamines, an acid acceptor is not always needed because HCl can be evaporated from the reaction mixture. The general reaction is given by... 

Hot-melt polyamide resins are obtained by the reaction of diamines with diacids. While in their simplest form polyamides are the reaction of a particular diamide with a particular diamine, most of the polyamides used in adhesive formulations are complex reaction products obtained by combining several diacids and diamines to obtain the particular properties required. The most common diacid used is a dibasic acid obtained by polymerizing oleic or linoleic acid or other unsaturated fatty acids. This acid can be represented as HOOC—R—COOH, where R is a hydrocarbon residue of 34 carbon atoms and of indeterminate configuration. Commercial forms of this dimeric diacid also contain preparations of products obtained by polymerization of three or more molecules of... 

It has been found that carbonyl bislactam is much more reactive than the other bislactam compounds mentioned above. Carbonyl bislactam can be obtained through the reaction of the lactam with phosgene. Preferably, the carbonyl bislactam is added to the melted polyamide or polyester product stream in the polymerization process as it leaves the polymerization reactor. 

An alternative route involves the reaction of acid chloride and amine at low temperatures to form high-melting polyamides ... 

Cyclohexanedimethanol dibenzoate adhesive modifier, hot-melt polyamides... 

Kampf Rudolf (2006). The Method for Producing Polymers by Means of Condensation in Melt (Polyamides, Polysulfones, Polyarylates etc) Germany Patent Application 102004034708. International Patent Catalogue C 08 P 85/00. 

Havenith HGJ, Sour WJM, Tijssen J, Leeuwen-dal RM. High-melting polyamide composition for electronic applications. US patent 6441072, assigned to DSM N.V., Heerlen, NL 2002. 

Polycondensation of terephthalic acid with hexamethylene diamine leads to a high-melting polyamide that can only be spun from concentrated sulfuric acid because of its high melting point of 370°C. 

Typical adhesives in each class are Liquids 1. Solvent—polyester, vinyl, phenolics acrylics, rubbers, epoxies, polyamide 2. Water—acrylics, rubber-casein 3. Anaerobics—cyanoacrylate 4. Mastics—rubbers, epoxies 5. Hot melts-polyamides, PE, PS, PVA 6. Film—epoxies, polyamide, phenolics 7. Pressure-sensitive—rubbers. 

Elastomeric (nitrile and urethane), hot-melt (polyamide and polyester), and reactive (epo, urethane, acrylic, and ( anoacrylate) adhesives have been used for bonding nylon. 

Yoda, N., 1963, Syntheses of polyanhydrides. XII. Crystalline and high melting polyamide-polyanhydride of methylenebis(p-carboxyphenyl) amide,/. Polym. Sci. Part A 1323-1338. 

Polyamides-6,6, -6,10 and -6, can be nucleated with 0,1% highly disperse silica. Polyamide-6,6 powder is used as a nucleant for lower melting polyamides. Other nucleants such as molybdenum disulfide, iron sulfide, titanium dioxide, talc and sodium phenylphosphinate are used [4]. 

Figure 7. Effect of LiCl on the melting temperature of polycaprolactam. (0,9) = Direct synthesis, (O) = 0.5 mol % initiator and catalyst, (9) = 1 mol % initiator and catalyst, (7 ) = salt added to melted polyamide.

Hot melt Polyamide, polyester, polyolefin-type 0.001 Less than 0.005 Less than 0.2 Less than 0.05 Less than... 

To the third class belongs most of the low melt high melt polyamides. 

In addition to the sources mentioned, special hot melt polyamides derived from dimer acid are available from Bostik Division of Emhart Corp., Terrell Industries, and Dexter Hysol. Some of these polymers are listed in Tables 5 and 6. 

Hot melt applicators for melting polyamides are available from several suppliers, notably, Nordson, Meltex Corp., Bostik Fastening Systems Group, and Graco/LTI. 

Another high melting polyamide fiber, Nylon-4,6 was commercialized after 1990 by DSM in Europe under the trademark Stanyl . The attractive properties of this polymer were known since the days of Carothers [6-9], but due to the high Tm (around 300 °C) it proved to be impossible to prepare a high molar mass polymer without discoloration by polycondensation in the melt. In the 1970s Caymans et al. [10]. elaborated a successful, two-step procedure. At first a prepolymer is produced in water under pressure at 200-215 °C. The second step... 

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