Crystallinity of poly

The crystallinity of poly(lactide- (9-glycoHde) samples has been studied (36). These copolymers are amorphous between the compositional range of 25—70 mol % glycoHde. Pure polyglycoHde was found to be about 50% crystalline whereas pure poly-L-lactide was about 37% crystalline. An amorphous poly(L-lactide-i (9-glycoHde) copolymer is used in surgical cHps and staples (37). The preferred composition chosen for manufacture of cHps and staples is the 70/30 L-lactide/glycoHde copolymer. 

Although it is a polar polymer, its electrical insulating properties at room temperature are good even at high frequencies owing to the fact that since room temperature is well below the transition temperature dipole orientation is severely restricted. Some data on the crystallinity of poly(ethylene terephthalate) are presented in Table 25.5. 

Blends of enzymatically synthesized poly(bisphenol-A) and poly(p-r-butylphenol) with poly(e-CL) were examined. FT-IR analysis showed the expected strong intermolecular hydrogen-bonding interaction between the phenolic polymer with poly(e-CL). A single 7 was observed for the blend, and the value increased as a function of the polymer content, indicating their good miscibility in the amorphous state. In the blend of enzymatically synthesized poly(4,4 -oxybisphenol) with poly(e-CL), both polymers were miscible in the amorphous phase also. The crystallinity of poly(e-CL) decreased by poly(4,4 -oxybisphenol). 

R.J. Lehnert, P.J. Hendra, N. Everall and N.J. Clayden, Comparative quantitative study on the crystallinity of poly(tetrafluoroethylene) including Raman, infra-red and F nuclear magnetic resonance spectroscopy, Polymer, 38(7) (1997) 1521-1535. 

Acrylic Fibers. Table VII shows that crystallinity of poly acrylonitrile is only slightly modified by heat treatments. The fraction of crystalline material seems rather distorted, as judged by the k values. Wet treatments alone allow substantial amounts of distortions to be removed. Water molecules could enter the ordered regions and relax dipole-dipole interactions, allowing some molecular motion. 

Blending of polymers is an attractive method of producing new materials with better properties. Blends of aliphatic polyesters, especially of poly(e-CL), have been investigated extensively and have been the subject of a recent review paper [170]. Poly(e-CL) has been reported to be miscible with several polymers such as PVC, chlorinated polyethylene, SAN, bisphenol A polycarbonate, random copolymers of Vdc and VC, Vdc and AN, and Vdc/VAc, etc. A single composition-dependent Tg was obtained in the blends of each of these polymers with poly(e-CL). This is of interest as a polymeric plasticizer in these polymers. Blends of PVC and poly(e-CL) with less than 50 wt % of poly(e-CL) were homogeneous and exhibited a single Tg. These blends were soft and pliable because the inherent crystallinity of poly(e-CL) was destroyed and PVC was plasticized... 

The value obtained for for poly (L-methionine), 50 erg cm, is significantly higher than the corresponding value of 34 erg cm for poly(L-norleucine). Since for a sufficiently hydrophobic polymer is closely related to the work of cohesion, this would contribute to the markedly higher crystallinity of poly (L-methionine). 

Degree of thermal diffusion is an important factor in treating rapid annealing, since it will govern in-depth crystallinity of poly-Si films formed and thermal damage to glass substrates. One-dimensional thermal diffusion coefficient can... 

Erb T, Zhokhavets U, Hoppe H, Gobsch G, Al-lbrahim M, Ambacher O (2006) Absorption and crystallinity of poly(3-hex)dthiophene)/fullerene blends in dependence on annealing temperature. Thin Sohd Films 511-512 483... 

The liquid crystallinity of poly(3-alkylthiophene) has been pointed out [121]. Enhancement of crystallinity by molecular alignment in a liquid crystal phase is prominent in poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b] thiophene) exhibiting a lamellar mesophase. When a thin film of the polymer fabricated by the spin-coating method is annealed at 100 °C, domain size remarkably extends from several tens of nanometers to a several micrometers, maintaining molecular alignment within domains because of the thermal motion of the polymer chains. The hole mobility of the thin film transistors based on this polymer reached 0.7 cm2 V-1 s 1 [122]. 

Nanofibers based on poly(vinyl alcohol) as the matrix, and nanocrystals of a-chitin (ca. 31 nm in width and ca. 549 nm in length) as the nanofiller were prepared by Junkasem et al. [51]. The average diameters of the electrospun fibers ranged between 175 and 218 nm. The addition of increasing amounts of the whiskers caused the crystallinity of poly(vinyl alcohol) within the nanocomposite materials to decrease and the glass transition temperature to increase. 

S., Scherf, U., Lieberwirth, 1., 2006, Effect of molecular weight on the structure and crystallinity of poly(3-hexylthiophene), Macromolecules 39, 2162-2171. 

Kricheldorf, H.R., Behnken, G. and Sell, M. (2007) Influence ofisosorbide on glass-transition temperature and crystallinity of poly(butylene terephthalate). Journal of Macromolecular Science, Part A. Pure and Applied Chemistry, 44 (7), 679-684. 

U. Zhokhavets, et al.. Relation between absorption cuid crystallinity of poly(3-hexylthiophene)/fullerene films for plastic solar cells. Chemical Physics Letters, 2006. 418(4-6) p. 347-350. 

Bai YW, Chen XE, Wang XH, Zhou QE. Study on liquid crystallinity of poly(A-vinyl-... 

Crystallinity of poly(ethylene terephthalate) as a function of annealing temperature determined using X-ray diffractometry, IR spectroscopy and DSC... 

Figure 5.23 presents the calculated crystallinity of poly(ethylene terephthalate) as a function of annealing temperature using DSC and X-ray and IR spectroscopy data. It can seen that the estimates of vary greatly. DSC is clearly the least sensitive to the effect of annealing on the sample crystallmity. 

C.M., Gomez Ribelles, J.L., and Lanceros-Mendez, S. (2011) Xailoring the morphology and crystallinity of poly(L-lactide acid) electrospun membranes. ScL Techncl. Adv. Mater., 12, 015001. 

Table 1. Effect of cooling rate on X-ray crystallinity of poly(l,4-i4Knylme ether)...

The crystallinity of poly(CHD) is estimated by X-ray diffraction (XRD). Three major peaks (d = 5.28, 4.51, and 3.91 A) are observed in its XRD spectrum in most cases. Although differential scanning calorimetry (DSC) has been adopted to investigate Tjn, the degree of polymer crystallinity cannot be quantitatively determined because the heat of fusion (AH ) value (in J/g) of a poly(CHD) single crystal has not yet been determined. 

The methods of DSC and IR spectroscopy were used to study various blends of poly(3-hydroxybu-tyrate) with ethylene-propylene copolymer rubber (EP). When the weight fractions of the initial pol5miers are equal, a phase inversion takes place as the blends are enriched with EP, the degree of crystallinity of poly(3-hydroxybutyrate) decreases. In blends, the degradation of poly(3-hydroxybutyrate) begins at a lower temperature compared to the pure polymer and the thermooxidative activity of the ethylene-propylene copolymer in the blend decreases in comparison with the pure copolymer. 

Steinhart et al. demonstrated that both polymer melt and solution could be employed in the wetting of ordered porous alumina to obtain nanotubes. This was exemplified among others by an ordered array of poly(tetrafluoro-ethylene) (PTFE) nanotubes prepared from the melt (Figure 5.59). It could be shown that wetting from the melt or a solution had profound consequences for the crystallinity of poly(vinylidene difluoride) (PVDF) nanotube walls. The nanotube thickness or the inner diameter of the nanotube could be tuned by varying the concentration of the polymer solution. " " ... 

The crystallinity of poly(vinyl chloride) may be substantially reduced when a suspension polymerization is carried out with vinyl chloride in the presence of a seed polymer latex of PVC and a modest quantity of acetic acid [51]. 

Sequence The difference in reactivity between comonomers affects the composition and also alters the placement of the monomer units along the chain. In the case of living polymerization, sequential monomer addition leads to the formation of block copolymers. However, when a random copolymer is targeted, reactivity differences can lead to nonrandom distribution of monomer units. If the incorporation of a comonomer B is intended to disrupt crystallinity of poly( A), uninteimpted sequences of A can lead to domains of crystallinity. For example, block copolymers of ethylene-propylene are highly aystaUine, while random copolymers are completely amorphous. 

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