Structural Studies of Crystalline Linear Polyethylenes as Revealed by Factor Analysis of Their Raman Spectra

Shen, Chengbo; Peacock, Andrew J.; Alamo, Rufina G.; Vickers, Thomas J.; Mandelkern, L.; Mann, Charles K.

doi:10.1366/0003702924123971

Cited by 22 publications

(9 citation statements)

References 34 publications

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“…Disordered units, both trans and gauche , are also present in relatively small amounts. A similar interpretation was given to the results of a factor analysis of the Raman spectra of linear polyethylene . A third component was found to be present.…”

Section: Resultssupporting

confidence: 71%

A Carbon-13 NMR Study of the Phase Structure of Semicrystalline Polymers: Hydrogenated Polybutadiene

Kitamaru¹,

Nakaoki²,

Alamo³

et al. 1996

Macromolecules

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A carbon-13 solid-state NMR study was made of a set of model random ethylene copolymers, namely the hydrogenated polybutadienes. By adopting appropriate pulsing sequences, the different elements of phase structure were isolated and the characteristics of the crystalline, amorphous, and crystalline−amorphous interfacial regions were established. The relative amounts and the thicknesses were determined for each of these regions. The results obtained by the NMR method agree very favorably with those previously reported by Raman spectroscopy with identical copolymers.

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Section: Resultssupporting

confidence: 71%

A Carbon-13 NMR Study of the Phase Structure of Semicrystalline Polymers: Hydrogenated Polybutadiene

Kitamaru¹,

Nakaoki²,

Alamo³

et al. 1996

Macromolecules

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“…Additional eigenvectors are probably due to cr ystallinity and m olecular orientation differences within each plastic type as well as the presence of additives, ® llers, impurities, and therm al degradation products from the laser. 30,31,32 Nevertheless, Fig. 2 demonstrates that the ® rst two loading vectors provide enough information to discriminate between the six plastic types.…”

Section: Resultsmentioning

confidence: 97%

Post-Consumer Plastic Identification Using Raman Spectroscopy

1999

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Raman spectroscopy is evaluated as a spectroscopic method for identification of common household plastics for recycling purposes. The methods of K-nearest neighbor (KNN), cyclic subspace regression (CSR), and library searching are compared for computerized plastic classification. Plastics studied consist of polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, and polystyrene. With principal component analysis (PCA), visual distinction between the different plastics becomes possible. Correct class membership to all six plastic types is provided by KNN. To date, all development and uses of CSR have been based on building models for each prediction property analogous to the form of partial least-squares known as PLS1. Cyclic subspace regression is modified in this paper to also allow modeling of multiple properties, as does PLS2. The new form of CSR was able to correctly classify all six plastic types when seven-factor models were used. This paper reports that key observations made in comparing PCR to PLS1 are verified for the interrelationships of PCR and PLS2 models. Most notable is that even though PLS2 uses spectral responses and plastic identifications to form factors, PLS2 eigenvector weights are not much different from PCR eigenvector weights where PCR only uses spectral responses to form eigenvector weights. Library searching showed less significant results than KNN and CSR. Regardless of the identification approach, polyethylene samples could be identified as either being high density or low density with the use of Raman spectroscopy.

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“…Recently, some work was done on PCA and deconvolution of heavily overlapped spectra (24–26). We used the statistical data processing methods of PCA and then MCR to resolve the spectra presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

Interaction of Dicarboxylic Metalloporphyrins with Liposomes. The Effect of pH on Membrane Binding Revisited¶

Kępczyński¹,

Ehrenberg²

2007

Photochemistry and Photobiology

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The acid–base properties of Zn‐hematoporphyrin IX (ZnHP) and Zn‐mesoporphyrin IX (ZnMP) and the effect of pH on their binding to liposomes have been studied. The ionization constants for the two carboxylate groups of ZnHP were calculated by principal component analysis and are 5.7 ± 0.1 and 6.9 ± 0.05. The neutral species and the mono‐ and dianionic forms all bind to liposomes, but a strong pH effect on the binding constant was observed for both the investigated compounds. We also observed a decrease in the binding of the two anionic species when the membranes carried a negative charge. These results indicate that the porphyrins partition into the membrane with their carboxylic moieties near the lipid–water interface so that their deprotonation, leading to a charged molecule, does not prevent the insertion of the tetrapyrrole ring into the lipid environment of neutral liposomes.

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Structural Studies of Crystalline Linear Polyethylenes as Revealed by Factor Analysis of Their Raman Spectra

Cited by 22 publications

References 34 publications

A Carbon-13 NMR Study of the Phase Structure of Semicrystalline Polymers: Hydrogenated Polybutadiene

A Carbon-13 NMR Study of the Phase Structure of Semicrystalline Polymers: Hydrogenated Polybutadiene

Post-Consumer Plastic Identification Using Raman Spectroscopy

Interaction of Dicarboxylic Metalloporphyrins with Liposomes. The Effect of pH on Membrane Binding Revisited¶

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