Light scattering by helical fiber structures: Experimental models

Samples of two helically wound monofilaments were used as experimental models to check the theoretical expression for light scattering from helixes. A method of estimating the pitch and tilt of the helixes was outlined and the results were compared with measurements from microscopy. The agreement was satisfactory. Layer line streaking and splitting was observed and explained in terms of irregularity of the helical parameters. Samples of several helically wound monofilaments were also prepared and their scattering patterns were compared with those from native and regenerated cellulosic fibers.     

Flash hydrolysis deinking of laser print using degradable toner resin

The choice of vinyl polymers as the plastic matrix for the pigment in xerographic toner did not anticipate the deinking thrust which has swept the paper industry. The hydrolytic stability of the carbon-carbon bond in vinyl and diene copolymers has prevented the use of a plastic degradation strategy for toner removal. New toner resins based on alkali degradable plastics have been shown to allow up to 97% toner removal. Based on polyimide and polyesterimide toners (either magnetic or non-magnetic) developed by Xerox, this study uses flash hydrolysis in the presence of 0.5% alkali to repulp. The process operates on 200-300 second batches at 190−210°C. The best results were obtained using alkaline repulping and magnetic deinking coupled with washing. The alkali also inhibits the hydrolytic degradation of cellulose although it negatively impacts the brightness. Thus the use of a polymer resin containing a chemically sensitive function allows conversion of the toner to pigment fragments and water soluble oligomers. The former is best separated by magnetic deinking while the latter is removed by washing.     

Polymerization of α,α-disubstituted-β-propiolactones and lactams. 10. Crystalline structure,thermal and mechanical studies of statistical and block copolymers of pivalolactone and α-methyl-α-propyl-β-propiolactone

AB and ABA block copolyesters based on racemic poly(α-methyl-α-n propyl-α-propiolactone) (PMPPL) as a “soft” or elastomeric segment and polypivalolactone (PPL) as a “hard” or crystallizable segment have been synthesized and compared with random copolymers of the same composition. X-ray studies show the coexistence of polymorphic crystal forms for a given polymer in a given sample. Thermal and dynamic mechanical properties give clear evidence of heterophase structure corresponding to segregation of PPL and PMPPL. The crystalline phase clearly provides thermally reversible crosslinking in the ABA block copolymers. On stretching, the planar zigzag form of PMPPL is observed. Because of the domain structure, moduli of ABA samples are higher than those of PMPPL and their tensile strengths are similar to those of comparable styrene-butadiene block copolymers. The polymer synthesis was achieved by sequential monomer addition with tetrahexyl ammonium benzoate as initiator. For the ABA polymers the diammonium salt of sebacic acid provided a di-functional initiator. The agreement between calculated and observed molecular weights testify to the “living” character of this polymerization reaction.     

A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery.     

Isomorphism in the poly(3,3-bis-hydroxymethyloxetane) family and copolymers: Poly (3,3-bis-hydroxymethyloxetane-co-3-methyl-3-hydroxymethyloxetane)

Copolymers of 3,3-bis-hydroxymethyloxetane, BHMO, 3-metyl-3-hydroxymethyloxetane, MHMO, or with 3-ethyl-3-hydroxymethyloxetane, EHMO, monomer units were characterized by x-ray fiber diffraction, differential scanning calorimetry and ¹³C solid-state nuclear magnetic resonance (NMR). The copolymers are statistically random and crystalline throughout the range of compositions. Both P(BHMO) and P(MHMO) appear to crystallize in the same crystal form. The fiber repeat indicates a planar zigzag backbone conformation, c(fiber axis) = 4.77 ± 0.03 Å. Similarities in the x-ray fiber diagrams as well as a linear dependence of T_m with composition of copolymer with no change in fiber diagrams indicates isomorphism, a phenomenon in which the random substitution of MHMO monomeric units into the crystalline lattice of P(BHMO) occurs without hindering crystallization of the resulting copolymer. © 1994 John Wiley & Sons, Inc.     

Synthetic magnetic opals

We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.