Bulk properties of synthetic polymer-inorganic salt systems. V. Mechanical properties of oriented poly(caproamide)

Single filaments of nylon-6 and of its mixtures with KCl, LiCl, and LiBr (salt content up to 5% w/w) were prepared by extrusion at 265°C. As-spun filaments with a varying degree of orientation were obtained by altering the take-up velocity a t constant outflow velocity. These as-spun filaments were further subjected to controlled thermal and mechanical treatments. Determinations of the elastic modulus, of birefringence, of wide-angle x-ray scattering, and of shrinkage were carried out for the as-spun and for the treated filaments. While KCl caused no detectable alteration of the properties of nylon-6, lithium halides caused a considerable increase of the elastic modulus of the polymer. Under the conditions adopted, moduli up to 14 GPa were obtained. The birefringence of as-spun fibers was, however, lower when lithium salt was present. Greater shrinkage a t 170°C was exhibited by the salted than by the pure polymer. The body of results has been interpreted in terms of a more efficient orientation of the extruded polymer when lithium salt is present. The latter effect is associated with the role of these salts in reducing the crystallization rate and in increasing the melt viscosity of the polyamide as characterized in preceding papers of this series. Lithium salts also favor the α → γ transformation between the two crystalline forms of nylon-6. The transformation was, however, reversed under sufficiently high applied stress.     

The bulk viscoelastic properties of poly(styrene-co-sodium styrene-p-carboxylate)

The effect of up to 7.82 mol % ionic groups on the stress relaxation and dynamic mechanical (torsion pendulum) properties of poly(styrene-co-sodium styrene-p-carboxylate) was studied. The results obtained were compared with those reported elsewhere for polymers containing the same ionic groups at a different position on the polystyrene backbone (styrene-sodium methacrylate copolymers) and with polymers containing different ionic groups at the same position (styrene-sodium styrene-p-sulfonate copolymers). The results of these comparisons showed that positioning of ionic groups affects the size of ionic aggregates formed, while their type dictates the strength of the forces within the aggegrates.     

Effect of poly(ethylene oxide) on the structure and properties of poly(vinyl alcohol)

To improve the drawability of poly(vinyl alcohol) (PVA) thermal products, poly(ethylene oxide) (PEO), a special resin with good flexibility, excellent lubricity, and compatibility with many resins, was applied, and the Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WXRD) were adopted to study the hydrogen bonds, water states, thermal properties, crystal structure, and nonisothermal crystallization of modified PVA. It was found that PEO formed strong hydrogen bonds with water and PVA, thus weakened the intra‐ and inter‐hydrogen bonds of PVA, changed the aggregation states of PVA chains, and decreased its melting point and crystallinity. Moreover, the interactions among PVA, water, and PEO retarded the water evaporation and made more water remain in the system to plasticize PVA. The existence of PEO also slowed down the melt crystallization process of PVA, however, increased the nucleation points of system, thus made more and smaller spherulites formed. The weakened crystallization capability of PVA and the lubrication of PEO made PVA chains to have more mobility under the outside force and obtain high mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1946–1954, 2010     

Dynamooptical and electrooptical properties of poly(methylphenylsiloxane) in solution and bulk

The dynamooptical, electrooptical, and hydrodynamic properties of a low-molecular-mass poly(methylphenylsiloxane) containing 33% phenyl radicals (with respect to the total amount of side groups) in dilute solutions and in bulk are studied. The size of macromolecules, as well as the molecular mass of the polymer, its shear optical coefficients Δn/Δτ = (0.29 ± 0.3) × 10^?10 (in decalin) and (0.43 ± 0.03) × 10^?10 cm s²/g (in bulk), and the specific Kerr constants K = (2.30 ± 0.02) × 10^?12 (in benzene), (2.23 ± 0.02) × 10^?12 (in decalin), and (2.24 ± 0.09) × 10^?12 cm⁵/[g (300 V)²] (in bulk), are estimated and compared with the corresponding characteristics of poly(dimethylsiloxane). The effect of solvents on the intramolecular mobility, optical anisotropy, and dipole structure of polymer macromolecules is considered.     

Effect of micelle structure on the spectral properties of poly(dimethylsilylene)

The absorption and fluorescence spectral features of an intractable poly(silylene), poly(dimethylsilylene) (1), in aqueous micelles--attributable to an elongated transoid backbone conformation encompassed by three micelles--are discussed.     

Effect of Molecular Weight on the Properties of Poly（butylene succinate）

Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.     

Effect of tacticity on permeation properties of poly(methyl methacrylate)

The effect of stereoregularity on gas permeation properties of poly(methyl methacrylate) (PMMA) was investigated. The gas permeability coefficients for He, H₂, O₂, N₂, Ar, CH₄, and CO₂ at 35°C near atmospheric pressure have been measured for three different PMMAs. Apparent diffusion and solubility coefficients were obtained from time lag data, and these were compared with data for a commercial PMMA previously reported. The permeability, solubility, and diffusion coefficients increase as the content of syndiotactic sequences increases. These observations are consistent with more dense packing of the isotactic form in the glassy state that stems in part from its lower glass transition temperature. The transport behavior for a 50:50 isotactic/syndiotactic blend was also studied. These so-called stereocomplexes exhibit permeation behavior comparable to other weakly interacting miscible blend systems.     

Effect of thermo-mechanical cycles on the physico-chemical properties of poly(lactic acid)

Polylactic acid (PLA) has now become an economically viable commodity plastic in many industries. This raises the question of recyclability of industrial production waste and some packaging wastes as well. The evolution of rheological and mechanical properties of polymer with the number of recycling cycles up to seven was investigated. For PLA, only the tensile modulus remains constant with the thermo-mechanical cycles. In contrast, stress and strain at break, rheological factors and the modulus and hardness probed by nanoindentation decrease for PLA. This dramatic effect is ascribed to a large decrease in the molecular weight due to several different complex degradation processes which are discussed. The effect of two stabilizers is also assessed.     

Effect of chloroform on the structure and gas-separation properties of poly(ether imides)

The FTIR spectra of poly(ether imide) films prepared from their chloroform solutions were recorded in a wide temperature interval. The cast films were shown to contain residual solvent. This residual solvent existed in films as unbound chloroform that may be removed by heating to 60–70°C and as bound chloroform that is involved in complex formation with polymers and may be removed by heating at temperatures close to their glass transition temperatures (180°C). Quantum-chemical calculations were performed for structures that model fragments and monomer units of poly(ether imides), as well as their complexes with chloroform. Chloroform was shown to be capable of preferential binding with an oxygen atom in a Ph-O-Ph′ fragment via hydrogen bonds. In this case, the conformational set of poly(ether imide) chains is changed. The above evidence is invoked to explain changes in transport characteristics with time for poly(ether imide) films cast from chloroform solutions.     

Effect of sepiolite nanoparticles on the properties of novel poly(sulfone ether imide)

A new poly(sulfone ether imide) was prepared, and related nanocomposites were produced through introduction of sepiolite nanoparticles into the matrix of polymer. Inherent viscosity, thermal and mechanical features of pristine poly(sulfone ether imide), and nanocomposite samples were evaluated and compared. The crystallinity was also investigated. Dispersion and distribution behaviors of nanocomposite samples and cross‐sectional morphology of nanocomposite films were also studied. Also, the optimized amounts of sepiolite nanoparticles in the matrix of polymer were determined by microscopic techniques (scanning electron microscope and transmission electron microscope). By introduction of 3 wt% of sepiolite, superior thermal and mechanical properties were observed. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of thermal degradation on rheological properties for poly(3-hydroxybutyrate)

Thermal degradation at processing temperature and the effect on the rheological properties for poly(3-hydroxybutyrate) have been studied by means of oscillatory shear modulus and capillary extrusion properties, with the aid of molecular weight measurements. Thermal history at processing temperature depresses the viscosity because of random chain scission. As a result, gross melt fracture hardly takes place with increasing the residence time in a capillary rheometer. Moreover, it was also found that the molecular weight distribution is independent of the residence time, whereas the inverse of the average molecular weight is proportional to the residence time. Prediction of average molecular weight with a constant molecular weight distribution makes it possible to calculate the flow curve following generalized Newtonian fluid equation proposed by Carreau as a function of temperature as well as the residence time.     

Studies on synthesis and properties of poly(ferrocenyldimethylsilanes) and poly(ferrocenylmethylphenylsilanes)

Poly(ferrocenyldimethylsilane) and poly(ferrocenylmethylphenylsilane) have been prepared via the thermal ring-opening polymerization of the corresponding strained, silicon-bridged ferrocenophanes. It was found that the molecular weights of resultant polymers depend on the polymerization time. Their electrochemical behavior in aqueous electrolytes was investigated by cyclic voltammetry.     

弹性体偶联剂结构对PVC/PPC性能的影响

NBR－PPC弹性体偶联剂能促进PPC（聚丙撑碳酸酯）与PVC（聚氯乙烯）之间的相容性，改善共混物的力学性能，并在共混体系中产生轻度交联。偶联剂组成在NBR／PPC比例为70／30，NBR（丁腈橡胶）含腈量为34％，BPO过氧化苯甲酸用量为2．5份时，共混物的综合力学性能最佳，但偶联剂预先硫化时间不宜过长．     

Effect of poly(vinyl acetate) (PVAc) on thermal behavior and mechanical properties of poly(3-hydroxybutyrate)/poly(propylene carbonate) (PHB/PPC) blends

To assess the compatibility of blends of synthetic poly(propylene carbonate) (PPC), with a natural bacterial poly(3-hydroxybutyrate) (PHB), a simple casting procedure of blend was used. poly(3-hydroxybutyrate)/poly(propylene carbonate) blends are found to be incompatible according to DSC and DMA analysis. In order to improve the compatibility and mechanical properties of PHB/PPC blends, poly(vinyl acetate) (PVAc) was added as a compatibilizer. The effects of PVAc on the thermal behavior, morphology, and mechanical properties of 70PHB/30PPC blend were investigated. The results show that the melting point and the crystallization temperature of PHB in blends decrease with the increase of PVAc content in blends, the loss factor changes from two separate peaks of 70PHB/30PPC blend to one peak of 70PHB/30PPC/12PVAc blend. It is also found that adding PVAc into 70PHB/30PPC blend can decrease the size of dispersed phase from morphology analysis. The result of tensile properties shows that PVAc can increase the tensile strength and Young’s modulus of 70PHB/30PPC blend, and both the elongation at break and the tensile toughness increase significantly with PVAc added into 70PHB/30PPC.     

Effect of synthetic route on structural and morphological properties of poly(thiophene-co-indole)

In this study, homopolymers of polythiophene (PT), polyindole (PIN) and their composites and copolymers were synthesized by chemical polymerization and were characterized by FTIR and UV-spectroscopy, and conductivity measurements. The conductivities of polymers, composites and copolymers were measured by a conventional four probe method at room temperature and different temperatures. Among the products, PT-PIN copolymer which was synthesized at polythiophene conditions revealed the highest conductivity with a value of 0.28 S cm^?1. The thermal properties of the samples were investigated by using thermogravimetric analyses, and it was found that they have quite good thermal stability. X-ray diffraction spectra showed that the amorphous nature of the polymers. Morphological properties of the polymers, composites and copolymers have been investigated by scanning electron microscopy.     

Anisotropic properties of poly(ethylene terephthalate) by Brillouin spectroscopy: Anisotropic properties of oriented bulk and nanostructured poly(ethylene terephthalate) determined by Brillouin spectroscopy and birefringence experiments

Using Brillouin spectroscopy (BS), the tensor of the elastic constants of oriented poly(ethylene terephthalate) was determined for a variety of morphologies obtained by different uniaxial drawing procedures. The extreme values of the moduli along the drawing direction at frequencies of a few gigahertz were C₃₃ = 40 GPa and C₄₄ = 1.8 GPa. As a result of the invariants of the single‐phase aggregate model, the oriented state is dominated by the Reuss average even at extreme draw ratios and subsequent to a deformation‐induced crystallization. This is documented in both the BS orientation parameter and the BS mode numbers in comparison with birefringence. Additional spectral lines observed at draw ratios larger than 6 are discussed in relation to the formation of nanostructured phases. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1201–1213, 2002     

添加剂对PVDF膜结构和性能的影响

以亲水性的聚乙二醇(PEG)和聚乙烯吡咯烷酮(PVP)为添加剂,利用浸没沉淀相转化法制备聚偏氟乙烯(PVDF)多孔膜。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅立叶-红外光谱仪(FT-IR)对所制得膜进行表征测试,分析了添加剂对膜孔结构、结晶度和膜性能的影响。结果表明:添加剂能有效改善膜的孔径结构,使得膜的微孔增多、孔间连通性增强、膜结晶度降低,达到提高膜的纯水通量和孔隙率的效果。     

Effect of amorphous precipitated silica on the properties and structure of poly(p-phenylene sulfide)

Using a precipitation technique, silicas were obtained from sodium metasilicate solution employing an acidic agent. Alcohol solutions were used in the process of production of highly dispersed silicas, which resulted in partial blocking of the silica surface silanol groups. Moreover, studies on morphology and microstructure using transmission electron microscopy and scanning electron microscopy were performed. The size distributions of primary particles and aggregate and agglomerate structures were determined using a ZetaPlus instrument using the dynamic light scattering method. The structure and molecular dynamics of the nanocomposite, consisting of poly (p-phenylene sulfide) (PPS) and of the precipitated silica, were studied using atomic force microscopy and nuclear magnetic resonance. It was proved that during annealing the fragmentation of PPS agglomerates takes place. This phenomena probably resulted from repulsion forces existing between agglomerates and aggregates. Fragmentation in the polymer network probably resulted from repulsion forces between agglomerates and smaller aggregates. Received: 7 November 2000 Accepted: 5 April 2001     

Effect of 1,1,3-trihydroperfluoro-1-propanol on the properties of poly(ethylene terephthalate) films

Modification of poly(ethylene terephthalate) films with 1,1,3-trihydroperfluoro-1-propanol was performed. Introduction of the modifier favors an increase in the degree of crystallinity and orientation of glycol residues in the trans position, thus improving the operation characteristics of the polyester.