Polyamide end groups

Various approaches have been undertaken for reactive compatibilization of poly-amide/ABS alloys. Maleic anhydride can be grafted to the ABS. Styrene maleic anhydride (SMA) copolymers have been employed as compatibilizers for polyamide/ABS blends. SMA and SAN copolymers are miscible when the AN and maleic anhydride (MA) contents are equal. The impact strength of these blends has been found to be sensitive to the amount and composition of the SMA copolymer. Addition of SMA to SAN/polyamide blends was found to enhance the tensile and impact properties of these blends. Imidized acrylic polymers have been used as compatibilizers for nylon-6/ABS blends. Glycidyl methacrylate and methyl methacrylate (GMA/MMA) copolymers are used as compatibilizing agents. The epoxide functionality in GMA is capable of reaction with polyamide end groups. GMA/MMA copolymers can be shown to be miscible with SAN over the range of AN content of ABS. Styrene/GMA copolymers have been reported to be used as compatibilizers for polymer pairs such as... 

Since the anhydride functional (maleated) rubbers have been found by many investigators to be one of the most useful system for polyamide toughening, this system will be discussed in more detail, particularly with respect to the effect of various parameters such as the polyamide end groups, rubber composition, and particle size on the toughening efficiency. 

Polyamide-imides may also be produced by reacting a diacid chloride with an excess of diamine to produce a low molecular mass polyamide with amine end groups. This may then be chain extended by reaction with pyromellitic dianhydride to produce imide linkages. Alternatively the dianhydride, diamine and diacid chloride may be reacted all together. 

Blends based on polyolefins have been compatibilized by reactive extrusion where functionalized polyolefins are used to form copolymers that bridge the phases. Maleic anhydride modified polyolefins and acrylic acid modified polyolefins are the commonly used modified polymers used as the compatibilizer in polyolefin-polyamide systems. The chemical reaction involved in the formation of block copolymers by the reaction of the amine end group on nylon and anhydride groups or carboxylic groups on modified polyolefins is shown in Scheme 1. 

Polyamide 6 is produced by ring opening polycondensation of e- caprolactame. If no other reactants are used, the polymer chains contain one carboxylic acid and one amine end group. 

There are two different oligomer series present in all spectra. The oligomer series can be identified by calculating the masses of the end groups and assigning them to specific chemical structures (Pasch and Schrepp, 2003 Weidner et al., 2004). In the present example, the two species are the propionic amide-acid (R-am-ac) and the propionic amide-propionic amide polyamides (R-am-am-R). The use of MALDI-TOF MS as a structure-sensitive detector allows the resolution to be indirectly enhanced since several species coelute, as shown in Fig. 17.21. The polarity of the... 

The molar ellipticity of these dendrimers was found to increase proportional to the number of chiral end groups. This is to be expected, in the absence of interactions between the terminal tryptophane moieties. No higher-generation dendrimers of this type have been reported. Other amino-acid-containing chiral dendrimers have been described by Meijer et al. who attached various amino acid derivatives to the periphery of poly(propylene imine) dendrimers (see Sect. 3) and more recently by Liskamp et al. (modification of polyamide dendra) [22] and Ritter et al. (synthesis of grafted polymerizable dendrimers containing L-aspartic acid components) [23]. 

The end group functionality of condensation polymers is typically defined by the monomers employed to make these materials. An example is shown below for a common polyamide polymer, namely nylon (see Figure 2). These polymers... 

Firstly, catheter sample 1 was dissolved in deuterated trifluoroacetic acid, and the solution analyzed by [H NMR spectroscopy. The [H NMR spectrum of the sample is shown in Figure 52. The peaks at 1.16 ppm, 2.56 ppm, and 3.40 ppm are consistent with a polyamide-12 (PA-12) structure. The signal at 3.58 ppm can be attributed to tetramethylene glycol (TMG) protons adjacent to the ether linkages. The signal at 1.60 ppm is composed of overlapping resonances from both components. The smaller peaks are most likely due to polymer end groups or protons at the junction of two blocks the material is an amide-ether block... 

Figure 14.3 Reaction of 1,4-PBO chain extender with PET end groups (carboxylic acid groups) to give linear chain extension of PET (leading to a polyamide-polyester) 1,4-PBO, 1,4-phenylenebisoxazoline...

Another method of achieving the desired molecular weight is by addition of a small amount of a monofunctional monomer, a monomer with only one functional group. Acetic acid or lauric acid, for example, are often used to achieve molecular weight stabilization of polyamides. The monofunctional monomer, often referred to as a chain stopper, controls and limits the polymerization of bifunctional monomers because the growing polymer yields chain ends devoid of functional groups and therefore incapable of further reaction. Thus, the use of benzoic acid in the polyamide synthesis yields a polyamide (XI) with phenyl end groups that are unreactive toward polymerization. 

Calculate the feed ratio of adipic acid and hexamethylene diamine that should be employed to obtain a polyamide of approximately 15,000 molecular weight at 99.5% conversion. What is the identity of the end groups of this product Do the same calculation for a 19,000-molecular-weight polymer. 

Polycarbonates, polyesters and polyamides having 8-hydroxyquinoline end groups are prepared by carrying out the polymerizations in the presence of monomers such as derivative (121) (76MI11103), which act as chain terminators. The polymers could be chain-extended... 

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