CHARACTERIZATION OF GAMMA-IRRADIATED CRYSTALLINE POLYMER .3. THERMAL-BEHAVIOR OF GAMMA-IRRADIATED POLYAMIDE-1010

Thermal behaviour of gamma-irradiated plain PA1010 and PA1010 containing different amounts of difunctional cross-linking agent BMI was investigated. In DSC endo- and exotherm, it was found that during irradiation, the presence of BMI markedly changes the melting and crystallisation characteristics of PA1010. A supposition that the network of BMI-containing specimens is rather loose in structure was proposed to explain the discrepancy in thermal behaviour between these two kinds of specimens. The supposition was further ascertained by the less brittleness in mechanical property of specimens containing BMI. Besides, the complexity of the thermal behaviour of gamma-irradiated PA1010 was discussed and attributed mainly to the increase in sigma-e, the fold surface free energy of chain fold crystals.

WATER-SOLUBLE AND AMPHIPHILIC POLYMERS .7. SYNTHESIS AND CHARACTERIZATION OF A NOVEL COMB-TYPE AMPHIPHILIC POLYMER PAMC16S

A novel comb-like amphiphilic polymer, poly (2-acrylamidohexadecylsulfonic acid) (PAMC16S), was synthesized by free radical polymerization of the corresponding amphiphilic monomer in 1,4-dioxane-water mixed solvents. Depending on the ratio of water/dioxane in the solvent, the reaction proceeded by either precipitation polymerization or micellar polymerization. The molecular weight of the polymer obtained under similar conditions decreased and subsequently increased with the increase of water content in the mixed solvent. The polyion nature of PAMC16S was confirmed by viscosity data of ethanolic solutions. In addition, the polymer was characterized by solubility, IR, TG and wide angle X-ray diffraction methods.

FRACTAL BEHAVIOR OF SPINODAL DECOMPOSITION IN POLYMER BLENDS

Fractal behaviour of ramified domains in the late stage of spinodal phase separation in a binary polymer blend of poly(vinyl acetate) with poly(methyl methacrylate) was investigated by optical microscopic method. In the late stage of the spinodal decomposition, the fractal dimension D is about 1.64. It implies that some anomalous properties of irregular structure probably may be explained by fractal concepts.

GLASS-TRANSITION TEMPERATURE AND MOLECULAR-PARAMETERS OF POLYMER

A new relationship, which correlates the glass transition temperature (T(g)) with other molecular parameters, is developed by using Flory's lattice statistics of polymer chain and taking the dynamic segment as the basic statistical unit. The dependences of T(g) on the chain stiffness factor (sigma-2), dynamic stiffness factor (beta = -d ln-sigma-2/dT) and molecular weight of polymer are discussed in detail based on the theory. The theory is compared with experimental data for many linear polymers and good agreement is obtained. It is shown that T(g) is essentially governed by the chain stiffness factor at T(g). Moreover, a simple correlation between the parameter K(g) of the Fox-Flory equation (T(g) = T(g)infinity - K(g)/M(n)) and other molecular parameters is deduced. The agreement between theoretical predictions and experimental measurements of K(g) has been found to be satisfactory for many polymers.

RELATIONSHIP OF THE SEQUENCE DISTRIBUTION OF A POLYMER TO THE CATALYTIC ACTIVITY OF ITS ND COMPLEX

The sequence distribution of the monomeric units in the styrene-acrylic acid copolymer has been obtained by calculation. The probability of long sequences of styrene increases with an increase in the content of the monomer in the copolymer. The highest distribution of short sequences of styrene takes place for the copolymer containing equimolecular amounts of styrene and acrylic acid. The copolymer which has this latter structure is inadequate for the synthesis of highly active supported complexes. When the distributions of long and short sequences of styrene are approximately equal, the activity of the Nd and Fe prepared polymer complexes is higher.

ASSIGNMENT OF C-13 NMR-SPECTRA OF POLYMER WITH SEMIEMPIRICAL METHOD - SURVEY OF SPECTRUM OF SECONDARY CARBON OF 1,2-PBD

In chain molecules of 1, 2-PBD, there are two kinds of gauche arrangements, which is the cause of making the spectrum of the secondary carbon in main chain of the polymer split. In such a complex system, the gauche arrangements of the secondary carbon and the tertiary carbon occupy an important position. Hence, the contribution of the tertiary carbon to the chemical shifts of the secondary carbon has a decisive effect on the sequence structure distribution. In comparison the contribution of vinyl groups is ...

A NEW KIND OF CONDUCTING POLYMER POLYPYRROLE (PPY) BR- ION CHEMICAL SENSOR

The modification of conducting polymer polypyrrole(PPy) on glassy carbon(GC)by electrcchemical technique, and the study on doping effect of Br anion and electrochemical behavior of PPy film electrode were reported.A new kind of Br~- ion selective electrode has been prepared successfully.The mechanism of the electrode potential response is based on the doping effect of anion in the conducting polymer.Effect of polymerization conditions on the potential response characteristic is investigated in dtail.The PPy...

A NEW KIND OF ION-SELECTIVE ELECTRODE BASED ON CONDUCTING POLYMER FILM

Organic conducting polymers have attracted much interest in material science. This letter reports potentiometric response behavior of polypyrrole (PPy)polymer film electrodes prepared by electrochemical polymerization, and a new kind of ion selective

FROM DIMER TO POLYMER .2. EXTENDED TO SYSTEMS POSSESSING 2-FOLD SCREW AXIS OR GLIDE PLANE

The approach for constructing the qualitative band structure of a polymer from corresponding dimer has been extended to the system possessing two-fold screw axis or. glide plane. The classification of energy levels of the dimer in the present case depends on pseudo-symmetry/antisymmetry instead of psendo-in-phase/out-of-phase property of the orbitals. Several typical conductive polymers are then discussed follow this approach. Among them are cis-polyacetylene, polyparaphenylene with a twist ang...

Recovery and fate of three species of marine dinoflagellates after yellow clay flocculation

The recovery and fate of three species of dinoflagellates, Alexandrium tamarense, Cochlodinium polykrikoides and Scrippsiella trochoidea, after having been sedimented by yellow clay, were investigated in the laboratory. The effect of burying period in yellow clay pellet and mixing on the recovery of settled algal cells were studied. The morphological changes of algal cells in yellow clay pellet were also tracked. Results showed that there was almost no recovery for A. tamarense and C. polykrikoides, and the cells decomposed after 2-3 days after visible changes in morphology and chloroplasts. There was some recovery for S. trochoidea. Moreover, S. trochoidea cysts were formed in clay pellet during the period of about 14 days, with the highest abundance of 87 000 cysts g(-1) clay and the incidence of cyst formation of 6.5%, which was considered as a potential threat for the further occurrence of algal blooms. S. trochoidea cysts were isolated from yellow clay and incubated to test their viability, and a germination ratio of more than 30% was obtained after incubation for 1 month. These results showed the species specificity of the mitigation effect of yellow clay. It is suggested that cautions be taken for some harmful species and thorough risk assessments be conducted before using this mitigation strategy in the field.