Redistribution of impurities in crystallizing polymers

alvert, P.D.; Ryan, T.G.

doi:10.1016/0032-3861(78)90112-x

Cited by 65 publications

(24 citation statements)

References 8 publications

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“…Crystalline contents, which are values corrected by the real amount of organic polymer in each composite (70% as average), were calculated by using 209 J/g for a 100% crystalline polypropylene. 24 In all cases three pots containing about 10 mg of each sample were tested, thus confirming reproducibility of results.…”

Section: Characterization Proceduresmentioning

confidence: 87%

Polypropylene/mica composites modified by succinic anhydride–grafted atactic polypropylene: A thermal and mechanical study under dynamic conditions

García‐Martínez

Laguna

Areso

et al. 2001

J of Applied Polymer Sci

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ABSTRACT:In this study the thermal and mechanical behaviors of PP/mica composites, under dynamic conditions, are discussed on the basis of the changes induced by the presence of the interfacial modifier succinic anhydride-grafted atactic polypropylene, with different degrees of grafting, prepared in our laboratories by chemical modification of a by-product from industrial polymerization reactor. Changes in the interfacial activity, induced by the substitution of a very small amount of polymer matrix by the interfacial agent with different grafting levels, were conclusively obtained. The results obtained from either the thermal or the dynamic mechanical behavior led to the same conclusions, and agree with data obtained from macroscopic mechanical properties.

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Section: Characterization Proceduresmentioning

confidence: 87%

Polypropylene/mica composites modified by succinic anhydride–grafted atactic polypropylene: A thermal and mechanical study under dynamic conditions

García‐Martínez

Laguna

Areso

et al. 2001

J of Applied Polymer Sci

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“…Chain ends, low molecular weight oligomers, branches, additives, catalyst residue, and any other molecules that do not possess the symmetry needed to form crystals make up such “impurities”. These impurities are concentrated outside the lamellar structures of the polymeric crystals present in the solid state 48–55,94. The fact that these species, and in particular chain ends and catalyst residue, are concentrated in the amorphous regions around the growing crystallites where molecular mobility is favoured means that we can maintain sufficiently high rates of reaction even in the solid state 47,84.…”

Section: The Production Of Pet In the Solid Phase A Look At The Currmentioning

confidence: 99%

The Solid State Postcondensation of PET, 1

Gantillon¹,

Spitz²,

McKenna³

2004

Macro Materials & Eng

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Summary: A review of the processes underlying the solid state postcondensation of poly(ethylene terephthalate) (PET) is presented. Fundamental aspects of the reactions are treated, and it is shown that the rate of polycondensation in the solid state depends on the relative rates of two types of diffusion. On the one hand, the diffusion of reaction by‐products (physical diffusion) controls the rate of the forward reactions. And on the other hand the diffusion of end‐groups (chemical diffusion) allows the reaction to proceed.The transesterification of BHET to form PET.magnified imageThe transesterification of BHET to form PET.

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“…Inter-spherulitic fractures similar to those in Fig. 9 are reported in filled and unfilled highly crystalline polymers [25][26][27] and are attributed to a weak interspherulitic boundary caused by syneresis of impurities, low molecular weight additives, or an enrichment of a particular filler in the interspherulitic region. 28 Figure 9 discloses part of a broader systematic relationship between the applied hold pressure, the mold temperature, and the crystalline structure of polymers in ceramic moldings.…”

Section: (2) Solidification Of Moldingsmentioning

confidence: 84%

“…10 and 13 arises from an enrichment of low molecular weight additive. The segregation of low molecular weight additives or impurities from growing spherulites in POM 11,24 and other semicrystalline polymers 25,28 is widely discussed and is reported to enhance interspherulitic fracture 25,28 displayed here in Figs. 9 and 12.…”

Section: (4) Molding Defectsmentioning

confidence: 95%

Effect of Polymer Crystallinity on Morphology in Ceramic Injection Molding

Krug

Evans

Maat³

2001

Journal of the American Ceramic Society

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Many ceramic injection molding vehicles include semicrystalline polymers which characteristically adopt a spherulitic growth morphology. Usually the spherulites are rendered invisible by the opacity of the ceramic powder but in this study they are clearly visible. Polyoxymethylene (POM), has been used as the vehicle. The growth of the spherulites is shown to be dependent on cooling rate and hence on position in the molding. Furthermore, migration of low molecular weight additives by syneresis is shown to occur and to influence the crack path in the as-molded state. An unusual composite fractograph is shown in which fracture faces made after molding, after binder removal, and after sintering are contiguous. Only after molding does the crack path follow the spherulite boundaries; behavior that is also widely reported for unfilled POM.

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Redistribution of impurities in crystallizing polymers

Cited by 65 publications

References 8 publications

Polypropylene/mica composites modified by succinic anhydride–grafted atactic polypropylene: A thermal and mechanical study under dynamic conditions

Polypropylene/mica composites modified by succinic anhydride–grafted atactic polypropylene: A thermal and mechanical study under dynamic conditions

The Solid State Postcondensation of PET, 1

Effect of Polymer Crystallinity on Morphology in Ceramic Injection Molding

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