Copoly crystallinity

A cross-linked and crystalline copoly(ester—imide) containing an alkene function was made by reaction of an unsaturated diacid chloride containing a cychc imido group with ethylene glycol at low temperature (27). 

PAs have also been copolymerized with other polymer systems and, in particular", with polyesters and poly ethers. In the copoly esteramides the crystallinity is decreased by copolymerization, as the crystalline structure of the amide unit is very different from the ester unit. However, alternating polyesteramides behave as homopolymers with a glass ttansition temperature and a melting temperature intermediate to the polyester and the PA polymer (Figs. 3.10 and 3.11).23,24 Polyesters, such as PBT and PET, modified with a small amount of diamide are also copolymers that have a high order.24,73... 

Copoly(ether ester)s consisting of short-chain crystalline segments of PBT and amorphous poly(ether ester) of poly(tetramethylene terephthalate) exhibit a two-phase structure and can be used for the production of high-impact-strength engineering plastics. These very interesting materials with their outstanding properties understandably require stabilization to heat and UV exposure [45],... 

As one increases the proportion of hydroqulnone, the degree of crystalline order in the resulting copoly(aryl ether) will Increase. Block copolymers of Bis A-PSF and Bis S-PSF can be synthesized. 

Kricheldorf [17] studied liquid-crystalline cholesteric copoly(ester-imide)s based on 1 or 2. The comonomers to obtain these chiral thermotropic polymers were N-(4-carboxyphenyl)trimellitimide, 4-aminobenzoic trimellitimide, 4-aminocinnamic acid trimellitimide, adipic acid, 1,6-hexanediol, and 1,6-bis(4-carboxyphenoxyl) hexane. Apparently the poly (ester imide) chains are so stiff that the twisting power of the sugar diol has little effect. 

Copoly(ester ester)s belong to the family of thermoplastic elastomers (TPEs) and consist in general of thermo-reversible hard and elastic soft domains [11]. The copoly(ester ester) used here consists of 60% poly(butylene terephthalate), 35% poly(butylene adipate) and 5% 4,4 -methylenebis(phenyl isocyanate), and shows domain sizes of about 20 nm [12]. The material possesses a rubber plateau between the glass transition temperature of the mixed amorphous PBA/PBT phase (the PBT phase is semi-crystalline) at about -30°C and the melting point of the PBT at about 220°C. Due to the vulnerability of the amorphous PBA/PBT soft domains towards water attack [13] the PBT/PBA copoly(ester ester) is used here to study the existence of ESC of a chemical rather than a physical nature. For the sake of clarity it should be emphasized that no additives have been used in the copoly(ester ester) described here. 

By far the largest group of liquid crystalline polymers containing imide groups are copoly(esterimide)s (PEIs). These have been sub-divided into flexible copolymers containing aliphatic spacers and wholly aromatic copolymers. There are several reports of copoly(amide-imide)s and copoly(ether-imide)s (both thermotropic and lyotropic) and these are treated separately. There are only a few examples of wholly aromatic imide containing LCPs, as polyimides frequently melt well above their decomposition temperature. Successful attempts have been made to incorporate flexible spacers, but in most instances the spacers are based on ether units, and the polymer is more strictly classified as a poly(etherimide). 

In this section, the metal-cationic salts of copoly(ethylene-methacrylic acid) are called the ethylene ionomers. This ethylene ionomer is one of the well-known commercial ionomers, marketed under the trade name Surlyn by DuPont. Many ethylene ionomers have crystalline and amorphous phases of ethylene chain units as well as polyethylene. Therefore, there is a three-phase structure, with crystalline, amorphous, and ionic aggregate phases this is a unique characteristic of ethylene ionomers compared with other ionomers. Although the ionic aggregate structure of the ethylene ionomer has not been fully established, its structural model is represented5 as shown in Fig. 1. In ethylene ionomers, therefore, it is necessary that some physical properties should be considered by correlating to not only the ionic aggregates but also the crystalline phases. 

Fig. 7. The temperature dependence of the degree of crystallinity for the copoly(ethy-lene-methacrylic acid) and its zinc or sodium salt ionomers. The abbreviations of samples in inserted notations are the same as those of Figs 2 6.

V. Percec and D. Tomazos, Liquid-crystalline copoly(vinylether)s containing 4(4 )-methoxy-4 (4)-hydroxy-alpha-methylstilbene constitutional isomers as side groups. Polym. Bull. 1987, 75(3), 239-246. 

To reduce the cost, these elastomers have been diluted with some PBT homopolymer. Because of the chemical similarity between the hard segment of the copoly(ether-ester) elastomers and the PBT, they form fairly compatible blends. When the hard segment content in the copoly(ether-ester) is > 80 wt%, it was found to be completely miscible with PBT, showing a single T, amorphous phase and co-crystallization of the PBT segments of the elastomer with PBT homopolymer. As the hard segment content was lowered to < 60%, the blend exhibited incomplete miscibility, with two Tg s for two amorphous phases and also two separate crystalline phases. [Runt et al., 1989]. Nevertheless, a partial miscibility was indicated due to changes in the T observed in DSC and dielectric relaxation spectra. The partial miscibility and low interfacial tension between the phases makes the blend very compatible. 

Optical texture observations and X-ray investigations showed that the polyacrylate 41 PA 3 and the copolymer 45 (x=0.8) form nematic phases. The polymethacrylate 41 PMA 3 and the copoly ether 45 (x=0.55) display no liquid crystallinity at rest, but exhibit a virtual isotropic liquid-nematic transition a few degrees below Tg, as evidenced by miscibility studies. Copolyether 46 does not show any threaded or schlieren texture, which would be characteristic of a nematic. 

Finkelmann H, Walther M. 1996. Structure formation of liquid crystalline block copoly mers. Prog Pol Sci 21 951 979. 

There have been many attempts to change the melt flow properties of a polymer by incorporating a small amount of an anisotropic or an immiscible polymer. For example, Brody [220,221] demonstrated a windup speed up to 5000 m/min by adding a small amount of copoly(chloro-l,4-phenylene ethylene dioxy-4,4 -dibenzoate/terephthalate) (CLOTH) or copoly(4-hydroxybenzoic/6-hydroxy-2-naphthoic acid) into nylon-6,6. More recently, Vassi-latos [222] disclosed the melt spinning of nylon-6,6 at speeds up to 6000 m/min with the addition of a minor amount of liquid crystalline polymers such as CLOTH. This technique clearly offsets some of the cost advantages of high-speed spinning. 

Sin Sinh, L. H., Son, B. T., Tmng, N. N., Lim, D.-G., Shin, S. H., Bae, J.-Y. Improvements in thermal, mechanical, and dielectric properties of epoxy resin by chemical modification with a novel amino-terminated liquid-crystalline copoly (ester amide). Reactive Ftmctional Polym. 72 (2012) 542-548. 

Examination on a hot-stage polarized microscope, as well as SALS and DSC data let us to the conclusion, that all polymers derived from the mixture of DHBP-A and DHBP with suberyl dichloride (Series I) or sebacyl dichloride (Series II) behave as thermotropic liquid crystals. For most of them DSC scans revealed two endo-therms, which are believed to correspond to solid-to-liquid crystalline (Tm) and mesophasic-to-isotropic (Ti) transitions. In few cases, i.e. for polycimidoester derived from DHBP-A with sebacyl dichloride and the copoly-amidoesters of Series II in which DHBP-A content exceeded 40 mol%, the multiple melting endotherms were observed. Though the similar phenomena were demonstrated by several authors (11,12) their origin is still not clear. 

In view of the results of this work it can be concluded, that partial replacement of ketone groups by alternating them with amide groups in the rigid part of the macromolecules, produces thermotropic liquid crystalline copoly-amidoesters of increased transition temperatures and broadened mesophasic ranges. 

Differential scanning calorimetry was used to study the non-isothermal crystallization behavior of blends of poly(phenylene sulfide) (PPS) with the thermotropic liquid-crystalline copoly(ester amide) Vectra-B950 (VB) [126], The PPS crystallization temperature and the crystallization rate coefficient increased significantly when 2-50% VB was added. The Ozawa equation was shown to be valid for neat PPS as well as for the blends. The values of the Avrami exponents matched well against those determined previously using isothermal analysis, and they are independent of the concentration of VB. 

K.-Y. Hsu, T.-C. Chang, and C.-H. Li, Studies on thermotropic liquid-crystalline polymers Part X. Synthesis and properties of crossUnkable aromatic copoly(ester)s containing conjugated double bonds. Journal of Polymer Science Part A Polymer Chemistry, 31, 971 (1993). 

Li Xin-Gui Huang Mei-Rong (1999). High-resolution thermogravimetry of liquid crystalline copoly (p-oxybenzoateethyleneterephthalate-m-oxybenzoate), J. Arml. Polvm. Sci.. 73(14), 2911-2919. 

Random copoly(p-phenylene sulfide sulfone/ketone)s were easily prepared in high yield ( 95-99%) by the solution (NMP) condensation of sodium hydrosulfide (NaSH) with bis(4-chlorophenyl) sulfone (4,4 -dichlorodiphenyl sulfone) [80-07-9] and 4,4 -dichlorobenzophenone [98-98-2]. Copolymers with sulfone/ketone molar ratios > 25 75 were amorphous, whereas those with ratios < 25 75 were crystalline. These materials form tough, creaseable films and exhibit a linear increase in the Tg from 144 to 215°C, with increasing sulfone content (62). 

Copoly(amides) and copoly(esters) represent an important class of random copolymers. Figure 5.4 gives plots of the crystallinity level as a function of temperature for copolyamides of caprolactam with capryllactam at different compositions.(23)... 

Copolymers of hexamethylene sebacate with decamethylene adipate and decamethylene sebacate with hexamethylene adipate show eutectic type minima in their respective melting temperature-composition relations.(128) However, high levels of crystallinity, characteristic of the respective homopolymers, are formed over the complete composition range. This result is not characteristic of a random copolymer with a pure crystalline phase. In the latter case a significant reduction in crystallinity level and marked broadening of the fusion range is expected and is observed. It can be concluded that in each of these copoly(esters) both repeating units participate in a common lattice. 

The nucleophilic substitution approach was also used by several research groups for syntheses of polysulfides with broad variation of the chemical structure and of the reaction conditions [343-352]. For instance, a poly(thioether-ketone) was prepared from DFBP and dry Na2S with variation of the reaction medium [337]. N-Cyclohexylpyrrolidone was found to yield the highest molecular weights. In another publication random copoly(ketone sulfone sulfide)s were prepared by copolycondensation of 4,4 -dichloro-benzophenone and 4,4 -dichlorodiphenylsulfone with NaSH (222) [344]. The crystallinity was found to depend on the molar fraction of benzophenone moieties. 

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