SynopsisThe compatibility of poly(ethy1ene oxidehpolflmethyl methacrylate) (PEO-PMMA) blends were examined covering the complete composition range. Up to 20% of PEO content films were transparent and glass transition temperatures were determined by DSC and by refractive index vs. temperature measurements. Only one T, was obtained for these samples and the relationship between T8 and composition has been evaluated. At higher PEO content crystallization took place and the films were opaque. Melting temperatuures of PEO in blends were determined by DSC. Melting point depression was observed for increasing proportion of PMMA and the binary interaction parameter has been calculated. EXPERIMENTALSeveral samples of commercial PEO were used (2, = 4,000, 6,000, and 10,000 from Atlas Industrias Quimicas S.A.; and Bw = 7,500, 14,000, and 18,500 from Polyscience Inc.). PMMA (B, = 6x lo5) was prepared by conventional suspension polymerization.Physical mixtures of PEO of different molecular weights and PMMA covering the whole range of composition were prepared at room temperature as cast films from chloroform solutions. The resulting films were subjected

When single crystals of 6‐aminocaproic acid (ACA) are heated about 30°C below their melting point, polycondensation to nylon 6 takes place. The polymer crystallites are biaxially oriented towards each other and the relation between their orientation and that of the parent monomer crystal has been clarified. The kinetics of the process are characterized by three stages, (a) an induction period, (b) a stage in which monomer disappears at a constant rate while polymer of relatively low molecular weight is formed, and (c) a slow polycondensation of the polyamide chains after exhaustion of the monomer. Oligomer concentrations were below detectable limits at all stages of the process. Addition of monomer to the polyamide was retarded when ACA was kept from reaching its equilibrium vapor pressure (0.12 mm Hg at 170°C) by condensation on a cool surface or when an inert gas was admitted to the system. This was interpreted as suggesting that ACA is transported through the vapor phase to the propagating polyamide. A number of surfaces catalyzed the polycondensation of ACA vapor, but nylon 6 formed in this way on KCl crystals exhibited no preferred orientation. The linear dimer and trimer of ACA were also found to condense to nylon 6 in the crystalline state, although at a slower rate than the monomer. The solid‐state polycondensation of these oligomers was accelerated when they were exposed to the vapor of the monomer. Solid‐state polycondensation of single crystals of the linear dimer led also to biaxially oriented nylon 6.

SynopsisA delipidized proteolipid protein fraction was purified from organic solvent extracts of bovine cerebral cortex and studied by means of diffraction, electron microscopic, and ir techniques. Special use was made of an electron diffraction procedure which minimized the electron damage to the biological specimens. The ir spectroscopy of the apoprotein fraction indicated the presence of polypeptides in extended p-conformation, possibly in the antiparallel mode of packing. Electron microscopy of the fraction, negatively stained in organic media, made apparent the presence of both ordered and amorphous material. Only the former, characterized by repeating units of about 40-45 A in diameter and varying length, produced diffraction patterns in the selected area mode exhibiting a highly undistorted lattice. The two-dimensional cell parameters of the protein fraction were a = 4.79 A, b = 7.20 A, and y = 90'. The plane group symmetry, corresponding to the systematic absences, was p Zgg, consistent with the 6-pleated sheet structure of simple polypeptides.

Solid-state polymerization has long been an important tool in the preparation and study of oriented polymers'). In recent years, most of the research in this field has been devoted to the study of addition polymerization') or polymerization of cyclic monomers3), while little work has been done on solid-state polyesterification and related processes.We have now been able to prepare highly crystalline, biaxially oriented specimens of Nylon 11 by means of solid-state synthesis4! The reaction was camed out with single crystals of Il-aminoundecanoic acid (m. p. 187-188 " C ) sealed in evacuated ampoules mbar) and heated at 160 0,5 "C for several days. Under these conditions, the transparent, needle-shaped, single crystals of monomer were converted into biaxially oriented, polycrystalline aggregates of polyamide 11. After 188 h of reaction, for example, the number-average degree of polymerization of the sample reached values of43-48 as determined by conductimetric titrations of the amino end groups'). The product was also investigated by IR spectroscopy, whereby the presence of the amide 1(1640 cm-') and amide I1 bands (1 535 cm-') fully confirmed its chemical nature. The position of the amide V (675 cm-I)") and amide VI bands (575 cm-1)7,8), moreover, pointed to the fully-extended, planar conformation, triclinic variety of the polyamide generally known as alphaas opposed to the non-planar, pleated sheet conformation known as gamma-form''.'*'. This observation was later substantiated by X-ray diffraction evidence.The crystallographic analysis was carried out on rotation (flat-plate) and Weissenberg photographs taken from water-leached, needle-shaped, polycrystalline aggregates of Nylon 1 1. The needles were mounted with the a direction of the polymer crystallites parallel to the rotation axis. The Weissenberg plates were registered with a zero-layer type of setting, spanning the equatorial (001) and (010) reflections of the polymer. Some faint (100) streaks also present in the Weissenberg plates are due to the finite value of the orientation distribution function all over the reciprocal space. The four strong arcs in Fig. (la) at 4,41,3,75,3,70, and 11,95 A could be immediately indexed according to the triclinic unit cell of Nylon Il9.'O) (Tab. 1). The high, biaxial orientation of a ) Mailing address: Instituto de Investigaciones Fisicoquimicas, San Martin 683,1004 Buenos Aires, Argentina.

synopsisVapor of 6-aminocaproic acid (ACA) at a pressure of 0.12 mm Hg was observed to polymerize when placed in the presence of different types of surfaces, crystalline and amorphous, at temperatures around 170OC. Two clearly distinct stages of the process could be detected. The first was an induction period, during which the polymer phase must be nucleated. The length of this nucleation stage depended 01) factors not well understood.In the second stage, polymer was produced at a constant rate which seemed to be related to the vapor pressure of ACA. The polymer produced consisted of the characteristic radiating arrays of ribbonlike crystals known as spherulites. The spherulites, in turn, were made up of primary and secondary lamellae about 90 d thick. Electron diffraction studies showed that the polymer chains were folded within the lamellae. Further it ww proved by chemical and crystallographic arguments that adsorption and polymerization should be simultaneous processes.