Miscibility of polyester/nitrocellulose blends: A DSC and FTIR study

The miscibility of polyester/nitrocellulose blends was investigated by differential scanning calorimetry and Fourier-transform infrared (FTIR) spectroscopy. Two nitrocelluloses (NC) derived from wood and having different nitrogen contents (12.62 and 13.42%) were used. On the basis of the glass transition temperature criterion, poly(?-caprolactone) (PCL), poly(valerolactone), poly(ethylene adipate), and poly(butylene adipate) are miscible with nitrocellulose, whereas poly(α-methyl α-propyl β-propiolactone) and poly(α-methyl β-proiolactone) are immiscible. The T_g versus composition curves of PCL/NC blends do not follow a monotone function but exhibit a singular point at a critical PCL volume fraction of 0.51 for NC-1342 and 0.45 for NC-1262 in agreement with Kovacs' theory. A shift of 17 cm^-1 of the carbonyl stretching band was observed with PCL/NC blends and is taken as evidence for hydrogen bonding interaction between the PCL carbonyl group and NC hydroxyl group. The frequency difference between the free hydroxyl absorbance and the absorbances of the hydrogen-bonded species was found to be 85 cm^-1 in pure NC and 125 cm^-1 in PCL/NC blends; it indicates that the average strength of this interaction is stronger than the corresponding self-associated hydrogen bonding in pure NC. The presence of a dipole-dipole interaction between the nitrate-ester groups of NC and the carbonyl groups of the polyesters is reported. The relative strength of the hydrogen bonding and dipole-dipole interactions is discussed and correlated with polymer miscibility.     

Die quantitative Bestimmung der Sulfons?uren von Phenol, Naphthalin und Anthrachinon durch Chromatographie an S?ulen aus Cellulosepulver

Zusammenfassung Die quantitative Analyse von Sulfonsäuren des Phenols, des Naphthalins und des Anthrachinons durch Säulenchromatographie an Cellulosepulver wird beschrieben. Die einzelnen Säuren werden mit Gemischen aus n-Propanol-Chloroform-Wasser eluiert und alkalimetrisch bestimmt. Von den Phenolsäuren kann man das o- und p-Isomere sowie die Schwefelsäure bestimmen. Von den Naphthalinsulfonsäuren wird der Gehalt an Monound Disulfonsäuren sowie an Schwefelsäure bestimmt. Von den Derivaten des Anthrachinons lassen sich die 1-Sulfon-, sowie 1,5- und 1,8-Disulfonsäuren trennen. Von den nichtkatalytisch sulfonierten Produkten läßt sich der Gehalt an Mono-, an Disulfonsäuren und an Schwefelsäure bestimmen, sowie das Verhältnis zwischen 1- und 2-Anthrachinonsulfonsäuren. Eine Analyse dauert ungefähr 1–3 Std.

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Summary A quantitative analysis of sulphonic acids of phenol, naphthalene and anthraquinone by column chromatography on cellulose powder is described. The separation of the acids is achieved by elution of the sample with a propanol-chloroform-water mixture and the obtained individual acids are estimated by alcalimetric titration. By this method the determination of the para- and ortho-isomers of phenol sulphonic and sulphuric acid is possible. The naphthalenesulphonic acids are also separated and the amounts of sulphuric acid, mono- and disulphonic acids are determined. From the derivates of anthraquinone the separation of 1-sulphonic, 1,5- and 1,8-disulphonic acids is suecesfully performed. In the products obtained by non-catalytical sulphonation the mono-, disulphonic and sulphuric acids may be determined, also the ratio of 1- to 2-anthraquinone sulphonic acids. About 1–3 hours are required for a complete analysis.

     

Beitrag zur Papierchromatographie chlorierter Phenole

Zusammenfassung Es wurde eine chromatographische Methode ausgearbeitet, bei der sich das Papier zwischen zwei Glasplatten befindet und die Probe unmittelbar vor der Front des vorrückenden Lösungsmittels aufgetragen wird. Auf diese Weise gelang es, auch flüchtige Stoffe zu trennen, wie z.B. das o-Chlorphenol, das bei der üblichen Ausführung auch aus dem mit Formamid imprägnierten Papier entwich. Die vollständige Sättigung des Raumes zwischen den Gläsern mit Lösungsmitteldämpfen beeinflußte günstig die Trennung und die Bildung von regelmäßigen, runden Flecken.Von den untersuchten Systemen bewährt sich am besten ein System, bei dem Xylol als bewegliche Phase und Whatman-Papier Nr. 3, imprägniert mit einer 30%igen methanolischen Lösung von Formamid, als stationäre Phase diente. Mit Hilfe dieses Systems ließen sich sämtliche Produkte der direkten Chlorierung von Phenol, außerdem einige mono- und dichlorierte Kresole gut trennen. Aus den R _M -Werten ließ sich ableiten, daß die Beweglichkeit eine additive Funktion der einzelnen Substituenten ist. Die beschriebene Methode wurde zur betriebsmäßigen Überwachung der Phenolchlorierung eingeführt.

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Summary A chromatographic procedure has been worked out for the separation of chlorinated phenols, using paper placed between two glass plates. The-sample is introduced at the front of the advancing solvent. The fact that the space between the two glass plates is completely saturated by solvent vapours enhances the separation and the formation of regular, round spots. The method permits to separate without loss even the more volatile substances, such as phenol, o-chlorphenol, etc.On Whatman 3-paper impregnated with 30% methanolic formamide and with xylene as the mobile phase all products of direct chlorination of phenol and moreover some mono- and dichlorocresols can be separated satisfactorily. It is derived from the R _M -Values that the mobility is an additive function of the single substituents. The method has been introduced for checking industrial phenol chlorination.

     

Lithium and potassium isotope separation using radiofrequency spectroscopy

Separation of lithium and potassium isotopes has been achieved using the isotopic differences in the radiofrequency spectrum. The isotope separation was studied in a supersonic molecular beam magnetic resonance spectrometer, and enrichment factors up to 30 obtained.     

Intermediate level structure in the s2 state of the isolated ultracold ovalene molecule

Spectroscopic information pertaining to interstate coupling between the S₂ and S₁ electronic states of ovalene, whose electronic origins are separated by ≈ 1800 cm^?1, has been obtained by the interrogation of the fluorescence action spectrum and of the energy-resolved fluorescence in seeded supersonic beams.     

Spectroscopy of large molecules in inert gas clusters

Aromatic hydrocarbons provide nucleation centers for the formation of clusters of inert gases in high-flow supersonic beams. Large clusters of Ar, each containing a single tetracene (T) molecule, were prepared by supersonic expansion of the seeded gas at pressures p = 3000–13000 Torr and interrogated by laser-induced fluorescence spectroscopy Evidence is reported for homogeneous line broadening of large TAr_n clusters prepared at p? 8000 Torr.     

Synthesis and characterization of amphiphilic triblock polymers by copper mediated living radical polymerization

2-Dimethylaminoethyl methacrylate (DMAEMA) and 2-diethylaminoethyl methacrylate (DEAEMA) block copolymers have been synthesized by using poly(ethylene glycol), poly(tetrahydrofuran) (PTHF) and poly(ethylene butylenes) macroinitiators with copper mediated living radical polymerization. The use of difunctional macroinitiator gave ABA block copolymers with narrow polydispersities (PDI) and controlled number average molecular weights (M_n’s). By using DMAEMA, polymerizations proceed with excellent first order kinetics indicative of well-controlled living polymerization. Online ¹H NMR monitoring has been used to investigate the polymerization of DEAEMA. The first order kinetic plots for the polymerization of DEAMA showed two different rate regimes ascribed to an induction period which is not observed for DMAEMA. ABA triblock copolymers with DMAEMA as the A blocks and PTHF or PBD as B blocks leads to amphiphilic block copolymers with M_n’s between 22 and 24 K (PDI 1.24-1.32) which form aggregates/micelles in solution. The critical aggregation concentrations, as determined by pyrene fluorimetry, are 0.07 and 0.03 g dm⁻¹ for PTHF- and PBD-containing triblocks respectively.