Multiple endotherms in polyepichlorohydrin

Mendis, Leslie P.; Hepburn, C.

doi:10.1016/0032-3861(76)90140-3

Cited by 6 publications

(2 citation statements)

References 6 publications

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“…The thermograms of the unfractionated PECH samples (Figure 3b,e,h) are characterized by double melting peak endotherms, similar to those already reported in the literature. [28][29][30] Multiple melting peaks are common in some polymeric systems 31 and are generally related to the presence of several crystal sizes, perfection, and/or internal order. However, unlike (RS)-PECH, in which the relative proportion of the high and low melting peaks is comparable (Figure 3b), the main peak of the chiral polymers is undoubtedly the high melting one; the peak maximum is also higher (109 vs 112 °C), while the low melting peak maximum remains the same (98 °C).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Glycidyl Azide Polymers Using Isotactic and Chiral Poly(epichlorohydrin)s

Brochu¹,

Ampleman²

1996

Macromolecules

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Isotactic and chiral glycidyl azide polymers (GAPs) have been synthesized by the reaction of isotactic and chiral poly(epichlorohydrin)s (PECHs) with sodium azide in dimethylformamide at 95 °C. The azidation does not affect the isotacticity of the chains, but the polymer backbone is degraded in the process; a GAP of high molecular weight (100 kg/mol) is nevertheless obtained. Despite the high isotacticity of the polymer chains, the GAPs are not crystalline. Long reaction times favor the branching and/or the cross-linking of the polymer. The isotactic and chiral PECHs used as starting materials for the GAP syntheses have been prepared by the Vandenberg process using racemic or chiral monomers, leading thus to partially ((RS)-PECH) or completely ((R)- or (S)-PECH) isotactic polymers, respectively. They have been split into a soluble and an insoluble fraction by acetone extraction. The fractionation of chiral PECH withdraws from the polymer the incompletely isotactic chains coming from the presence of monomers of opposite configuration in the chiral epichlorohydrin or from a defective polymerization process. The population of crystals remaining in the insoluble chiral PECH fraction is thus more homogeneous, leading to an improved crystallinity and a higher melting temperature.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Glycidyl Azide Polymers Using Isotactic and Chiral Poly(epichlorohydrin)s

Brochu¹,

Ampleman²

1996

Macromolecules

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“…In order t o examine thermal crystallization of PECH, the following procedure was undertaken. The samples were melted a t 200°C [8] and then crystallized a t determined temperatures during 4 h. Such crystallization time ensures complete polymer crystallization, which was found out comparing crystallinity indexes of these samples and of samples crystallized during 24 h. Diffractograms of samples crystallized a t various temperatures did not show valid differences, i.e. they had identical number of peaks, the peaks had the same angular distribution, the only slight differences concerning the height of peaks and the half breadths.…”

Section: X-ray and Picnonietric Analysesmentioning

confidence: 99%

An analysis of structural changes in the process of thermal crystallization of poly(epichlorohydrin) by means of WAXS and microscopic methods

1985

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Act= Polymerica 36 (1905) Nr. 9 483 Strukturelle Besonderheiten und einige physikalisch-chemische Eigenschaften von aus nichtwaprigen Lcisungen erhaltenen Mischungen oon Cellulose und synthetischen Polymeren. 2. Hochauflcisende 13C-NMR von Mischungen aus Cellulose und synthetischen Polymeren im festen Zustund Mit Hilfe der hochauflosenden 13C-NMR-Spektroskopie wurden Mischungen von Cellulose mit Polymethylmethacrylat, Polyacrylnitril, Polyvinylacetat, Polyvinylalkohol und Polydimethylsiloxan mit unterschiedlicher quantitativer Zusammensetzung untersucht.

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Conflicts Between Ethics and Law in Counseling and Psychotherapy

Mappes¹,

Robb

Engels

1985

Jour of Counseling & Develop

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Codes of ethics are designed to guide and govern the behavior of the professional for whom they are written. In such fields as counseling, psychology, and social work, ethical standards are necessary to protect clients, guide professionals, safeguard the autonomy of professional workers, and enhance the status of the profession. Sometimes, however, the professional worker finds that the ethical standards of the profession seem to be in conflict with the law. These conflicts may arise in such areas as advertising, confidentiality, and clients' rights of access to their own files. The authors discuss the nature, ramifications, and implications of ethical-legal conflicts in the helping professions.

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Multiple endotherms in polyepichlorohydrin

Cited by 6 publications

References 6 publications

Synthesis and Characterization of Glycidyl Azide Polymers Using Isotactic and Chiral Poly(epichlorohydrin)s

Synthesis and Characterization of Glycidyl Azide Polymers Using Isotactic and Chiral Poly(epichlorohydrin)s

An analysis of structural changes in the process of thermal crystallization of poly(epichlorohydrin) by means of WAXS and microscopic methods

Conflicts Between Ethics and Law in Counseling and Psychotherapy

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