Poly-p-benzamide

Example 21. Poly (p -benzamide) from acid chloride.72... 

Acid anhydride-diol reaction, 65 Acid anhydride-epoxy reaction, 85 Acid binders, 155, 157 Acid catalysis, of PET, 548-549 Acid-catalyzed hydrolysis of nylon-6, 567-568 of nylon-6,6, 568 Acid chloride, poly(p-benzamide) synthesis from, 188-189 Acid chloride-alcohol reaction, 75-77 Acid chloride-alkali metal diphenol salt interfacial reactions, 77 Acid chloride polymerization, of polyamides, 155-157 Acid chloride-terminated polyesters, reaction with hydroxy-terminated polyethers, 89 Acid-etch tests, 245 Acid number, 94 Acidolysis, 74 of nylon-6,6, 568... 

Poly(arylene thioether)s, 363-364 Poly(arylene thioether sulfone)s, 364 Poly(aryl sulfone) derivatives, 354 Poly(p-benzamide), synthesis of, 188-189 Polybenzimidazoles (PBIs), 265 ferrocene-containing, 315 synthesis of, 313... 

Polyazo dyes, 9 363—361 Polybenzamide, 15 109-110 Poly(p-benzamide) (PBA), 10 212 19 714 crystal lattice parameters of, 19 728t laboratory synthesis of, 19 719 Polybenzimidazole (PBI), asbestos substitute, 3 3141 Polybenzimidazole (PBI) fibers,... 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

In concluding this section, we should touch upon phase boundary concentration data for poly(p-benzamide) dimethylacetamide + 4% LiCl [89], poly(p-phenylene terephthalamide) (PPTA Kevlar)-sulfuric acid [90], and (hydroxy-propyl)cellulose-dichloroacetic acid solutions [91]. Although not included in Figs. 7 and 8, they show appreciable downward deviations from the prediction by the scaled particle theory for the wormlike hard spherocylinder. Arpin and Strazielle [30] found a negative concentration dependence of the reduced viscosity for PPTA in dilute Solution of sulfuric acid, as often reported on polyelectrolyte systems. Therefore, the deviation of the Ci data for PPTA in sulfuric acid from the scaled particle theory may be attributed to the electrostatic interaction. For the other two systems too, the low C] values may be due to the protonation of the polymer, because the solvents of these systems are very polar. 

A major impetus was given to work, both academic and industrial, in the field of lyotropic systems by the development by duPont of commercial fibres having exceptionally high tensile strength and modulus through use of nematic anisotropic solutions of relatively rigid-chain aromatic polyamides. The earliest product to appear, Fibre B, was based upon poly (p-benzamide) (I)10), but was replaced by the fully commercial product, Kevlar, based upon poly (p-phenylene terephthalamide) (II) U). Arenka, from Akzo, also has the latter chemical repeating unit. 

These critical values differ from solvent to solvent. With the solvents most fully investigated, sulphuric acid for poly-(p-phenylene terephthalamide) and dimethyl acetamide/lithium chloride for poly (p-benzamide), there are also critical values of solvent composition the sulphuric acid must exceed a critical strength, the lithium chloride in the dimethyl acetamide must exceed a critical concentration. The critical values are, of course, interdependent rather than absolute. Diagrams that display some of the critical values for the two systems cited have been published in patents10,1 l Figures 3 and 4 illustrate the type of information available. 

Fig. 3. Phase diagram for solutions of poly-p-benzamide in dimethyl acetamide/lithium chloride I0). Polymer inherent viscosity 1.18...

The solution of pam-arormtic polyamides occupy a special place among the systems forming liquid crystalline order. Two typical representatives of this class of polymers turn out to be best studied owing to their practical importance. These are poly-(p-benzamide) (PBA)... 

Fig. 35. Graph of relative values of (ln]/[ri])/([n]/[ril)oo vs. parameter x for poly(p-benzamide) (1), poly(amide hydrazide) (2), poly(chlorohexyl isocyanate) (3), poly(7-benzyl-L-glutamate) (4), and polyCamide benzimidazole) (5)...

Fig. 39. G vs. X plot for various aromatic polymers samples 1 poly(p-benzamide) in sulfuric acid. Values of lx/g according to Ref. 44). Molecular weights are plotted according to data in Refs. 4, 55,142) (,1,, gjij Q respectively) 2 poly(p-phenylene terephthalamide) in sulfuric acid. Values of [x/g] plotted according to data in Ref. 143) and molecular weights according to data in Refs. 143,14i) respectively) 3 poly(amide hydrazide) in dimethyl sulfoxide.

Moreover, this bending and possible differences in the hindrance to intramolecular rotations explain " the variation in the segment length A between poly-(p-benzamide) and poly(p-phenylene terephthalamide) molecules (Table 9). 

M. Arpin and C. Strazielle, Characterization and conformation of aromatic polyamides poly(l,4-phenylene terephthalamide) and poly(p-benzamide) in sulphuric acid. Polymer, 18 (1977) 591-598. 

Polyamides Via the Phosphorylation Reaction Poly-p-benzamide (PBA) and iV-Methyl PBA Copolymers... 

Several routes for the synthesis of poly-p-benzamide (PBA) have been reported. The routes[1-2] that yield high molecular weight PBA (i.e., ninh 3.5 determined in cone, sulfuric acid) have employed acid chloride monomers, such as I or II (1-2). 

Figure 2. Weight loss curves for poly-p-benzamide and K-methyl poly-p-benzamide copolymers.

Reinforced Structural Resins. Polyesters and polyepoxides are reinforced with E- or S-glass strands, mats, or cloth raising their tensile strength 10-20 times and their modulus of elasticity 10-100 times, approaching the properties of steel. Reinforced with graphite, boron, or the new poly-p-benzamide fiber or whiskers, novel composites surpass steel. 

One of the basic problems confronting molecular composites is the difficulty of finding miscible combinations of rigid rod polymers with flexible chain polymers. Poly(p-phenylene benzobisthiazole)/poly(-2,5(6)-benzimidazole block copolymers have been reported by Tsai et al. [1985] and are noted to exhibit better processability and mechanical properties than the simple blends of the block copolymer constituents. Chang and Lee [1993] prepared poly(p-benzamide)/Pl block copolymers and reported on the liquid crystalline behavior. Such approaches would appear to have future implications. As an example PA e.g., PA-66) block copolymers with rigid rod polyamides could be prepared and used in blends with PA-66 to yield the desired molecular composite. 

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