Amorphous-crystalline polymers

Polymers are usually structured like spaghetti noodles piled together. There are two main types of polymers, amorphous or crystalline. Amorphous polymers are prepared by... 

Table 3.16. Influence of and upon the nucleation behavior in crystalline/amorphous polymer blends...

Table 3.19. Expressions for the dissipation energy terms and corresponding spherulite growth rates in a crystalline/amorphous polymer blend system [Martuscelli, 1984 Baitczak et al., 1984]...

In comparing the different blends, the specific advantages of each type, as well as any potential overlap in performance with other type of blends have also been discussed. The fundamental advantage of polymer blends viz. their ability to combine cost-effectively the unique features of individual resins, is particularly illustrated in the discussion of crystalline/amorphous polymer blends, such as the polyamide and the polyester blends. Key to the success of many commercial blends, however, is in the selection of intrinsically complementing systems or in the development of effective compatibilization method. The use of reactive compatibilization techniques in commercial polymer blends has also been illustrated under the appropriate sections such as the polyamide blends. 

The heat of fusion, AH is the energy involved in the formation and melting of crystalline regions. For semicrystalline polymers, as discussed in Section 3.10.3, the energy of fusion is proportional to the percent crystallinity. Amorphous polymers. 

Kelusky et al. also indicated that by use of a semi preparative TREF system one could achieve an effective characterization of PE/EPDM terpolymer and PE/polyisobutylene blends. The approach for this type of analysis of blends, in which one of the components was non-crystalline, was to first collect the PIB or EPDM by elution at 30 °C followed by elution of the PE component as an analytical TREF or it could be eluted off, precipitated and recovered for subsequent analysis by SEC or NMR. They point out that the TREF separation of this type of mixture is superior to the usual solvent extraction methods which invariably remove some highly branched or low molecular weight PE in addition to the PIB or EPDM. One would anticipate that such a separation scheme would be effective for other crystalline/amorphous polymer blends such as impact polypropylenes which contain ethylene-propylene rubber. 

PBSA and PVPh are miscible crystalline/amorphous polymer blends. Miscibility of PBSA/PVPh blends was evidenced by the single composition-dependent glass-transition temperature over the entire blend compositions. The negative polymer-polymer interaction parameter, obtained from the melting depression of PBSA, indicates that PBSA/PVPh blends are thermodynamically miscible. 

Table 3.23 Overview of literature in which the final semicrystalline morphology in immiscible crystalline/amorphous polymer blends has been studied ...

In most immiscible crystalline/amorphous polymer blends, the crystallization of the dispersed phase occurs in the presence of a molten matrix phase. In the following description, examples will be categorized according to the major classes, as listed in Table 3.14. 

Studies of finite dilution are not among the principal topics of this book. However, to determine interaction parameters of crystalline-amorphous polymers with injected volatile substances, the retention volumes at finite concentrations need to be measured. Therefore the method of elution on a plateau developed by Conder and PumeU [40,41] is presented briefly it was developed for the determination of thermodynamic data at finite concentrations of micromolecular stationary phases and extended to amorphous [42, 43] and crystalline-amorphous [44] polymeric stationary phases. 

Combining eqns (5.30) and (5.31) one obtains for interaction parameter of solute with crystalline-amorphous polymer ... 

The accuracy of the gas chromatographic results may be checked by comparison with those obtained through adsorption and diffusion of vapours in crystalline-amorphous polymers in gravimetric experiments [50-53]. 

For polar crystalline-amorphous polymers adsorption at the polymer-carrier gas interface becomes much more likely and the contribution of adsorption should be subtracted from the experimental specific retention volume both above and below In-... 

Fig. 5.6. — Illustration of the summing of specific retention volumes due to adsorption (curve 1) and dissolution (curve 2) to obtain the real retention diagram (curve 3) for a crystalline-amorphous polymer [171].

In all the above considerations it has been assumed that, within region III, the whole stationary phase interacts with the solute. This does not hold true for crystalline-amorphous polymers in which the interaction involves only the amorphous phase. Substitution of the crystalline fraction Jc given by eqn (5.54) into eqn (5.76) gives the retention volume of a crystalline-amorphous polymer ... 

Some polymers may undergo transitions above the glass transition temperature, which Boyer [224] called intermediate transitions at T > Tg for amorphous polymers and T, < T < T for crystalline amorphous polymers. Gas chromatography has demonstrated such a transition in poly(vinyl chloride) [205] it was attributed, as in liquid crystals, to the existence of a state with nematic order at temperatures between T, and... 

When a non-crystalline (amorphous) polymer is heated, a temperature exists at which the polymer changes from a glassy to a rubbery state. Figure II - 8 shows the variadon in the tensile modulus E of a completely amorphous polymer as a funcdon of the temperature. 

Plastics can be either amorphous or crystalline. Pure crystallinity is rare among polymers. Most polymers have crystalline and amorphous regions and are considered semi-crystalline. Amorphous polymers have low crystallinity or irregular crystalline regions. A listing of amorphous and crystalline polymers is found in Table A.2 (Belofsky 1995a). 

In conclusion, by means of the SANS micro-structural investigation method the structure and morphology of the crystalline-amorphous polymer-aggregates was resolved (Fig.llb). Of greater importance for further design and optimization of efficient polymer additives for wax crystal control was the understanding of the interaction mechanism between the polymers and waxes in this specific case. This mechanism has found commercial application of PE-PEB (ParaflowTM) as diesel wax modifiers. 

Figure 16.5 Lauritzen-HofFman plots showing spherulitic morphologies and kinetic regime behavior of crystalline/amorphous polymer blends in which the crystalline polymer was PCL and the amorphous polymer was varied.

Impact modified polymers Crystalline-amorphous polymer blends... 

Up to now, the study about phase-separation theory is mainly focused on amorphous/amorphous polymer blend and crystalline/amorphous polymer blend models. There is still lack of systemically theoretical guidance and support for crystalline/crystalline polymer blend models. Therefore, the establishment of the phase-separation theory... 

I. Crystallization of matrix in the presence of molten dispersed phase. The crystallization behavior of a crystallizable matrix in the presence of a molten dispersed phase can be compared to those found in a crystalline/amorphous polymer blend discussed earlier, in which the amorphous phase was in molten form [92]. 

Chen HL, Li LJ, Lin TL. Formation of segregation morphology in crystalline/amorphous polymer blends molecular weight effect. Macromolecules 1998 31(7) 2255—64. 

In equation (10) A is the fraction of non-crystalline (amorphous) polymer and is equal to xN — Cm)/xN. The entropy of fusion per repeating unit, is formally defined as kz... 

Phase Diagram Calculation of a Crystalline/Amorphous Polymer Blend... 

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