Modified polyamides

Siloxane containing interpenetrating networks (IPN) have also been synthesized and some properties were reported 59,354 356>. However, they have not received much attention. Preparation and characterization of IPNs based on PDMS-polystyrene 354), PDMS-poly(methyl methacrylate) 354), polysiloxane-epoxy systems 355) and PDMS-polyurethane 356) were described. These materials all displayed two-phase morphologies, but only minor improvements were obtained over the physical and mechanical properties of the parent materials. This may be due to the difficulties encountered in controlling the structure and morphology of these IPN systems. Siloxane modified polyamide, polyester, polyolefin and various polyurethane based IPN materials are commercially available 59). Incorporation of siloxanes into these systems was reported to increase the hydrolytic stability, surface release, electrical properties of the base polymers and also to reduce the surface wear and friction due to the lubricating action of PDMS chains 59). 

Some purely major groove-binding TFs, such as the basic-region leucine zipper (bZIP) protein GCN4, can co-occupy the DNA helix in the presence of polyamides [72]. Modified polyamides with an attached Arg-Pro-Arg tripeptide can interfere with major groove-binding proteins by disrupting key phosphate contacts, distort-... 

FIGURE 17.19 2D contour plot of a modified polyamide 6, first dimension LCCC, second dimension SEC. Area 1 unmodified chains, area 2 modified chains, area 3 cyclic oligomers. (See color plate.)... 

Using the same chromatographic system as given in Fig. 17.19 we were able to investigate modified polyamide 6.6 by 2DLC. The samples were modified by amidation with propionic acid, introducing additional functionality fractions to the system. In total, seven different species were expected to be present in the samples (see Table 17.1). 

Table 4.43 Neat, reinforced and modified polyamides 6 and 66 examples of properties...

Miettinen-Oinonen A, Puolakka A, Buchert J (2007) Method for modifying polyamide. Patent EP1761670 Finland... 

Amine-modified polyamides can be prepared by condensation with formaldehyde and aromatic amines at room temperature the pendant groups are reported to act as active centers for grafting of acrylonitrile, acrylamide, methyl methacrylate and N-vinyl pyrrolidone (152). 

In some cases semicrystalline thermoplastics have been used as modifiers (polyamides, polyesters). With these thermoplastics it is necessary to increase the temperature beyond the melting temperature to obtain a solution. 

The solubility of these dyes is significantly enhanced by introduction of alkenyl [35], hydroxypropyl [36], or polyetheralkyl [37] moieties into the trialkylammonium group. The trialkylammonium group may also be a component of a heterocyclic ring [38], When the trialkylammonium residue contains an alkyl chain of more than 11 carbon atoms, the dyes become soluble in aliphatic and alicyclic hydrocarbons and can be used for the production of printing inks [39], With aromatic diamines as the diazo components, such as 4,4 -diaminodiphenyl sulfone, basic disazo dyes are obtained which are suitable for dyeing acid-modified polyamide materials [40],... 

In streptocyanine dyes both ends of the methine chain are joined directly to nitrogen atoms, and a double enamine structure is thus present. The dyes are extremely susceptible to hydrolysis, particularly if they contain secondary nitrogen atoms. Stable dyes are obtained if the nitrogen is part of a heterocyclic ring system. Streptocyanine dyes are brilliant yellow dyes that dye polyacrylonitrile and acid-modified polyamide fibers with outstanding lightfastness [1],... 

Traditional polymers for separations in water have a limited chemical resistance and are not useful for solvent separations. Some may be applicable in nonaggressive solvents such as methanol and ethanol due to crosslinking, additives or additional interlayers, but not in any other solvent modified polyamide membranes and poly (ethersulfone) membranes are typical examples. 

Fig. 14.26 Diameter (SD, thickness (S7), and weight (Sw) swell of a parison extrudate from a commercial blow-molding machine equipped with CCD camera equipment and parison pinch-off mold based on the design of Shepak and Beyer (69). (a) A chain extended multibranched polyamide-6 resin (b) the former with 12% glass fiber of 10 pm diameter 60 1 L/D and (c) polyolefin modified polyamide-6 with some carbon black. [Reprinted by permission from A. H. Wagner and D. Kalyon, Parison Formation and Inflation Behavior pf Polyamide-6 During Extrusion Blow Molding, Polym. Eng. Sci., 36, 1897-1906 (1996).]...

Mason JP et al. (1997) Impact-modified polyamide-based molding composition. US Patent 5610223... 

Reten 205 [Aqualon], TM for a strongly cationic, high molecular weight, synthetic, water-soluble polymer. A finely divided white powder, dissolves in either hot or cold water to produce clear, smooth, viscous, nonthixotropic solutions available in a variety of viscosity grades and cationic functionality. Reten 763 is an aqueous solution of a modified polyamide-epichlorohydrin resin. 

The mechanical properties of the surface-modified products were examined by a special shear test. After reactive surface modification under optimised chemical and technological conditions, the test specimens were cut and the pieces were bonded by special adhesives. The coimected pieces were examined in a shear test and the shear strength was determined in dependence on the chemical and processing conditions. The best results for polyamides were obtained for polyacrylic acid as the modifier with an increase of the shear strength from 28 MPa (non-modified polyamide) up to 37 MPa for polyacrylic acid-modified polyamide surfaces. 

Table III. Oxygen Permeation Data for Modified Polyamides...

The large containers (e.g., automotive fuel tanks) were made using low concentrations, about 4% of the modified polyamide, in large "accumulator type" blowmolding machines (e.g. manufactured by Sterling Extruders, [USA] Kautex, [Germany]), equipped with low mixing extruder screws and other hardware. The... 

Another important combination is the use of polyamides reacted with air-drying alkyds. Certain alkyd resins can be combined with modified polyamide resins to furnish materials exhibiting a marked degree of thixotropy when dissolved in suitable solvents. This... 

Polyamide/Elastomer Blends (Impact modified polyamides)... 

The outstanding impact toughness of the commercial impact modified polyamides is attributed to the small particle size of rubber dispersion and their good degree of adhesion to the polyamide matrix. Typical morphologies of compatibilized polyamide/elastomer blends are shown in Figure... 

Commercial ABS/PA-6 blend exhibits excellent notched Izod impact (> 850 J/m) at room temperature and good drop weight impact (> 40 J) at -40°C. These impact properties are equivalent to the impact modified polyamide (Table 15.20). However, the DTUL (0.45 MPa) of ABS/PA blends are relatively low compared to those of impact modified nylons. The key difference being that in ABS/polyamide blends, due to the significant level of ABS, a substantial drop in the modulus occurs... 

The commercial grades of polyamide/polycarbonate blend (Dexcarb ) exhibit high notched Izod impact strength comparable to that of impact modified polyamides and polycarbonate (Table 15.24). It is believed that an elastomeric impact modifier was included in these compositions. Patent claims the use of a polyetheramide and a maleated polypropylene or EPR as the compatibilizing/ impact modifying additives [Perron, 1988]. The commercial grades contain varying amounts of PC, PA-66 (or 6) and the impact modifier. 

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