Alkylene melting points

With all six series of polyester illustrated in Figure 25.14, as the number of methylene groups in the repeating unit increases so the polymer becomes more like a linear polyethylene (polymethylene). Thus the melting points for five of the six classes are seen to converge towards that of the melting point of polymethylene. In the ca.se of the sixth class, the poly(alkylene adipates), there would appear no reason to believe that additional data on other specific members of the class would not lead to a similar conclusion. 

In the poly(alkylene arylate) series, Tm decreases with increasing length of flexible — (CH2) — moieties and, as in the aliphatic series, approaches the limiting value of polyethylene melting point for large n values (Table 2.6). Aromatic -aliphatic polyesters with even numbers of methylene groups melt at higher... 

TABLE 2.4 Melting Point, Tm (°C), and Glass Transition Temperature, 7 (°C), of Poly(alkylene adipate)s and Poly(alkylene terephthalate)s... 

Polar protic solvents, 91 Polar substituents, 277 Polk, Malcolm B., 529 Polyaddition reactions, 84-85 Poly(alkylene adipate)s, melting points of, 34... 

Poly(alkylene terephthalate)s, 89 melting points of, 34 Poly(alkylene terephthalate) solvents, 90-91... 

The structure of the diol in alkylene terephthalate/PTME terephthalate copolymers has an important effect on the properties of these block copolymers, as evident from the results shown in Tables II, III, and IV. The 50% tetramethylene terephthalate/PTME terephthalate copolymer prepared from 1,4-butanediol (4G) which was previously noted in Table I serves as our reference copolymer for purposes of discussing the effects of changing the structure of the crystallizable ester segments. The outstanding properties of the 4G-based copolymer are ease of synthesis, a rapid rate of crystallization from the melt, a high melting point, and excellent tensile and tear strengths. 

A plot of the observed melting points of the 50% alkylene tereph-thalate/PTME terephthalate copolymers vs. the range of melting points of the poly (alkylene terephthalate) homopolymers as taken from the literature (16,18-25) results in the linear relationship shown in Figure 3. 

Alkylene 2,6-Naphthalenedicarboxylate/PTME 2,6-Naphthalene-dicarboxylate Copolymers. Fifty percent alkylene 2,6-naphthalenedicar-boxylate/PTME 2,6-naphthalenedicarboxylate copolymers were prepared using each of the straight-chain, hydroxy-terminated diols from ethylene glycol (2G) to 1,10-decanediol (10G) (Table VIII). In contrast to many of the 50% alkylene terephthalate/PTME terephthalate copolymers of Table II, all of the 2,6-naphthalenedicarboxylate-based copolymers tested exhibit excellent tensile strength and tear strength regardless of the diol used or the melting point of the copolymer. As a consequence of their excellent properties, the 2,6-naphthalenedicarboxylate copolymers have been the subject of several patents (32,33,34). 

A plot of the measured melting points of the 50% alkylene 2,6-naphthalenedicarboxylate/PTME 2,6-naphthalenedicarboxylate copolymers of Table VIII vs. the reported melting points of the corresponding... 

Figure 4. The melting points of 50% alkylene 2,6-naphthalene dicarboxylate/FT ME 2,6-naphthalenedicarboxylate copolymers as a function of the melting points of the corresponding poly(alkylene 2,6-naphthalenedicarboxylate) homopolymers...

Figure 5. Copolymer compression set as a function of copolymer melting point for 50% alkylene ester/PTME ester copolymers (A = terephthalate O = 2,6-naphtha-lene-dicarboxylate )...

Note that the highest IDT was obtained with the cyclopenta-methylenehydantoin resin derived from cyclohexanone. It is tempting to speculate that this inflexible alkylene moiety was ineffective in shielding the hydantoin ring, but subsequent comparison of the hydrophobic-hydrophilic balance of amine-cured resins appeared to rule out this explanation probably the stiff spiro structure contributed to the high Tg, just as it contributed to the high melting point of the resin itself (lie). 

Decomposes when heated above melting point, 536°F/280°C, producing toxic fumes of arsenic, lead. Lead arsenates may be subject to redox reactions. Both arsenic and lead are known human carcinogens. PLUMBOUS ACETATE (6080-56-4) Pb(CjH302)2 3H,0 Contact with acids forms acetic acid. Incompatible with oxidizers, bases, acetic acid alkalis, alkylene oxides, ammonia, amines, bromates, carbonates, citrates, chlorides, chloral hydrate cresols, epichlorohydrin, hydrozoic acid, isocyanates, methyl isocyanoacetate, phenols, phosphates, salicylic acid sodium salicylate, sodium peroxyborate, potassium bromate resorcinol, salicylic acid, strong oxidizers, sulfates, sulfites, tannin, tartrates, tinctures trinitrobenzoic acid, urea nitrate. On small fires, use dry chemical, Halon, or CO2 extinguishers. 

A similar thermal behavior dependence on the alkylene unit has been observed for the CHDM containing poly(n-alkylen naphthal-ate)s copolyesters (55). PECN behaves similarly to PECT copolymers showing a window of intermediate compositions were the copolymers are amorphous. On the contrary, copolyesters of PBCN crystallize for all compositions with an eutectic point at about 41% of 1,4-CHDM. On the other hand, in the case of PHCN copolymers, it was observed a continuous increase in the melting temperature with the content in 1,4-CHDM, indicating the occurrence of unlimited isomorphic crystallization. 

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