Comparison of the toughening effects of different elastomers on nylon 1010

The toughness of three different elastomer‐toughened nylon 1010 blends was investigated via standard notched Izod impact test and single edge notched three‐point bending test. The toughness of nylon 1010 blends varies much with different elastomer types and components. All three kinds of nylon/elastomer/maleated‐elastomer blends showed high impact strength (over 50 kJ m^?2) as long as at appropriate blending ratios. With increasing maleated elastomer content, brittle‐ductile transition was observed for all three kinds of elastomer‐toughened nylon 1010 blends. The number average dispersed particle size (d_n) of ethylene‐1‐octene copolymers or ethylene‐vinyl acetate copolymers toughened nylon 1010 blends significantly decreased from over 1 to 0.1 μm with increasing corresponding maleated elastomer content. Investigation on the fracture toughness showed the dissipative energy density gradually increased with decreasing d_n, while the limited specific fracture energy increased with increasing d_n when d_n was below 1 μm and then sharply decreased with further increasing d_n. The energy consumed in the outer plastic zone was the main part of the whole energy dissipated during the fracture process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Graft copolymerization of methyl acrylate onto nylon1010 initiated by potassium diperiodatonickelate(IV)

In this article, the graft copolymerization of methyl acrylate (MA) onto nylon1010 by using potassium diperiodatonickelate(IV) [Ni(IV)]–nylon1010 redox system as initiator was studied in alkaline medium. The effect of different factors on grafting parameters was investigated. The structure of the graft copolymer was determined by infrared (IR), X-ray diffraction, and scanning electron microscope (SEM). It was found that Ni(IV)–nylon1010 system is an efficient redox initiator for this graft copolymerization. A single-electron transfer mechanism is proposed to explain the formation of radicals and the initiation. The graft copolymer was used as the compatibilizer in blends of poly(methyl methacrylate) (PMMA) and nylon1010. The SEM photographs indicate that the graft copolymer greatly improved the compatibility of the blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2636–2640, 2001     

Assessment of branching in polymers from small angle X-ray scattering (SAXS): SAXS from model comb-branched polystyrenes

Comb-branched polystyrenes having both fixed backbone length and number of branches but variable branch lengths were prepared anionically. Small angle X-ray scattering of the model polystyrenes from methyl ethyl ketone (MEK) solutions at 25°C was examined and it is shown that the mass per unit length and cross-sectional radius of gyration increase with increasing branch length. A maximum appears in the Kratky plot for the branched polymers. While the linear polymer displays an essentially Gaussian segment distribution in solution, the branched polymers deviate considerably from the behaviour of the linear polymer under the same conditions.     

Structural Investigation of Resorcinol Formaldehyde and Carbon Aerogels Using SAXS and BET

The structure of organic RF aerogels (RF Recorcinol Formaldehyde) and carbon aerogels, their pyrolized counterparts, can be modified upon variation of the resorcinol to catalyst (RC) ratio. RF aerogels with RC ratios between 100 and 1500 have been produced in steps of 100. The densities for the organic aerogels were kept in the range of 350 to 390 kg m^-3. After pyrolysis, these samples have nearly the same density as their RF precursors, except the ones with very low RC ratios. This is due to the combined shrinkage and mass loss during the heat treatment. All samples were investigated using small angle X-ray scattering (SAXS) and nitrogen sorption (BET) as well as transmission electron microscopy (TEM). Two main effects have been observed. On the one hand, the particle/pore diameter distribution widens with increasing RC ratio, i.e., decreasing catalyst concentration. The average pore diameter increases from 20 nm to about 100 nm. On the other hand the pyrolysis generates a considerable amount of micropores in the particles.     

Structural Data on the Periplasmic Aldehyde Oxidoreductase PaoABC from Escherichia coli: SAXS and Preliminary X-ray Crystallography Analysis

The periplasmic aldehyde oxidoreductase PaoABC from Escherichia coli is a molybdenum enzyme involved in detoxification of aldehydes in the cell. It is an example of an αβγ heterotrimeric enzyme of the xanthine oxidase family of enzymes which does not dimerize via its molybdenum cofactor binding domain. In order to structurally characterize PaoABC, X-ray crystallography and small angle X-ray scattering (SAXS) have been carried out. The protein crystallizes in the presence of 20% (w/v) polyethylene glycol 3350 using the hanging-drop vapour diffusion method. Although crystals were initially twinned, several experiments were done to overcome twinning and lowering the crystallization temperature (293 K to 277 K) was the solution to the problem. The non-twinned crystals used to solve the structure diffract X-rays to beyond 1.80 Å and belong to the C2 space group, with cell parameters a = 109.42 Å, b = 78.08 Å, c = 151.77 Å, β = 99.77°, and one molecule in the asymmetric unit. A molecular replacement solution was found for each subunit separately, using several proteins as search models. SAXS data of PaoABC were also collected showing that, in solution, the protein is also an αβγ heterotrimer.     

利用同步辐射X射线小角散射研究超低水灰比水化水泥早期微结构

利用同步辐射X射线小角散射技术表征超低水灰比水泥水化早期产物分形结构,研究水化水泥早龄期微结构及演变。水泥水化早期水化产物双分形结构表明：水泥水化硅酸钙纳米凝胶颗粒随机堆积,内外层水化产物中纳米凝胶粒子结构分别具备不同的自相似性;内层水化产物中高密度凝胶堆积紧密,早龄期时随水化时间增加,堆积密度降低。外层水化产物中低密度凝胶堆积较为松弛,早龄期时随水化时间增加,堆积密度也在降低;水化诱导期生成结构最为致密的一层凝胶产物,诱导期后,凝胶产物层堆积密度随水化龄期的增加而减小,水化反应平缓后,凝胶堆积密度的演变也趋于平缓。     

Effect of in situ surface‐modified nano‐SiO2 on the thermal and mechanical properties and crystallization behavior of nylon 1010

Nylon 1010 composites filled with two types of surface‐modified SiO₂ nanoparticles (RNS and DNS) were prepared by melt blending. The mechanical properties of the composites were evaluated. The influences of the surface‐modified nano‐SiO₂ on the thermal stability, crystallization behavior, and microstructure of nylon 1010 were investigated by thermogravimetric analysis, differential scanning calorimetry (DSC), X‐ray diffraction, and transmission electron microscopy. And the interfacial interactions between the fillers and polymer matrix were examined using a Fourier transformation infrared spectrometer. It was found that the addition of the surface‐modified nano‐SiO₂ had distinct influences on the thermal stability, mechanical properties, and crystallization behavior of nylon 1010. RNS and DNS as the fillers had different effects on the mechanical properties of nylon 1010. The composites filled with RNS at a mass fraction of 1–5% showed increased break elongation, Young's modulus, and impact strength but almost unchanged or even slightly lowered tensile strength than the unfilled matrix. The DNS‐filled nylon 1010 composites had obviously decreased tensile strength, whereas the incorporation of DNS also contributed to the increase in the Young's modulus of nylon 1010, but less effective than RNS. Moreover, the nylon 1010 composites had better thermal stability than the neat polymer matrix, and the composites filled with RNS were more thermally stable than those filled with DNS. The difference in the crystallinity of neat nylon 1010 and its composites filled with RNS and DNS was subtle, although the surface‐modified nano‐SiO₂ could induce or/and stabilize the γ‐crystalline formation of nylon 1010. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A SAXS study of the structure of gels formed by mixtures of polyoxyalkylene triblock copolymers

Small‐angle X‐ray scattering was used to characterise aqueous micellar gels of triblock copolymers E₁₃₇S₁₈E₁₃₇, E₈₂S₉E₈₂, E₇₆S₅E₇₆, E₆₂P₃₉E₆₂, and of two mixtures: E₁₃₇S₁₈E₁₃₇ and E₆₂P₃₉E₆₂ (Mix 1) and E₈₂S₉E₈₂ and E₆₂P₃₉E₆₂ (Mix 2), each 50/50 wt%. E = oxyethylene, CH₂CH₂O; S = oxyphenylethylene, OCH₂CH(C₆H₅); and P = oxypropylene, OCH₂CH(CH₃). Within the concentration and temperature ranges investigated (30–40 wt% copolymer, 20–80 °C), spherical micelles of copolymers E₁₃₇S₁₈E₁₃₇, E₈₂S₉E₈₂ and E₆₂P₃₉E₆₂ packed into body‐centred cubic (BCC) structures. Gels of E₇₆S₅E₇₆ were stable only at high concentrations and low temperatures, and a 70 wt% copolymer solution at T = 30 °C formed a hexagonal gel consistent with cylindrical micelles. It is likely that the mixed copolymers would form two distributions of micelles, and more complex structures were expected. However, gels of Mix 2 had well‐ordered BCC structures, while the less ordered gels of Mix 1 were also best characterised as BCC. Copyright © 2006 Society of Chemical Industry     

Surface chemistry and contrast-modified SAXS in polymer-based activated carbons

The adsorption of non-polar and polar molecules, n-hexane and water, on activated carbons, functionalized by oxidation with concentrated nitric acid, is investigated by small angle X-ray scattering. A relative mass density function p(q) is introduced in order to trace the filling characteristics of these probe molecules in the pore structure. Inspection of p(q) shows that while the pores affected by the applied relative pressure are completely filled by n-hexane, pore filling by water is only partial, even in the most oxidized carbon. The differences between the solid-liquid contact areas of these two molecules adsorbed from the vapour phase on the various carbons illustrate the influence of surface chemistry and molecular polarity on the contrast-modified SAXS response.     

Structural changes in non-isothermal crystallization process of melt-cooled polyoxymethylene[II] evolution of lamellar stacking structure derived from SAXS and WAXS data analysis

Structural change occurring in the cooling process of polyoxymethylene from the molten state has been investigated by carrying out the temperature dependent measurements of small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). In the SAXS experiment the generation of lamellar stacking structure with long period of ca. 14 nm was detected at first and then the new lamellae were inserted in between the already-existing lamellae to give the long period of 7 nm below 140 °C. The SAXS data were analyzed on the basis of lamellar insertion model by taking into account the second kind of paracrystalline disorder about the lamellar stacking mode. The thus obtained results were combined with the previously published infrared spectral data, and the structural change was deduced concretely. The generation of taut tie chains passing through the adjacent lamellae was proposed, which could reasonably explain the observation of infrared bands characteristic of extended-chain-crystal-like morphology.     

偶联剂处理纳米SiO2对尼龙1010力学与摩擦学性能的影响

用A171和KH550 2种硅烷偶联剂对纳米SiO2进行分散处理,然后用注射成型法制备了纳米SiO2/尼龙1010复合材料。研究了改性处理纳米SiO2对尼龙1010复合材料的结晶性能、力学性能以及摩擦学性能的影响。结果表明:纳米SiO2表面的改性处理均使尼龙1010基体的结晶度降低,而拉伸强度、硬度和耐磨性提高。A171处理纳米SiO2/尼龙1010复合材料的断裂伸长率大于纯尼龙1010。改性处理纳米SiO2使尼龙1010复合材料的摩擦因数降低。     

Synchrotron SAXS 〈in situ〉 identification of three different size modes for soot nanoparticles in a diffusion flame

The high photon flux (10¹⁴ photons/s) and high spatial resolution (∼100 μm) of synchrotron radiation available at ID09b/ESRF facility has been exploited in an in situ investigation of the early stages of soot formation in an ethylene-air diffusion flame. SAXS data demonstrate in situ evidence that the size distribution of soot nanoparticles within the flame exhibits three distinct modes at different heights above the burner z’s. In particular, at z ∼ 3 mm, small particles (4-6 nm size), called sub-primary particles, are observed to come into existence. The corresponding monomodal distribution is observed to evolve to bimodal one at z > 5 mm, with the sub-primary particle mode being progressively depleted in favor of the growth of a mode corresponding to larger primary particles (10-12 nm size). The sub-primary peak vanishes completely at about z ∼ 20 mm where distribution is again single mode about 12 nm diameter. Porod’s plots show that the sub-primaries are born as configurational flat entities similar to discs or lamellae with a small aspect ratio (Porod’s exponent about 2), and upon going to higher z’s, they approach a spherical form with a smooth surface (Porod’s exponent about 4). Moreover, the careful use of Kratky plots has allowed to demonstrate the presence within the flame of very small nuclei, sized about 1.5-2 nm, which have a nucleation burst at about z ∼ 5 mm, whose number concentration progressively decreases at larger z, finally disappearing around z ∼ 15 mm. The relative increase of primary particles (size larger than 12 nm) is found to correspond to the progressive decrease of these very small nuclei (∼2 nm) concentration. At heights larger than 15 mm a strong ionization signal is observed that increases with height. These findings are in agreement with previous experimental works in the literature performed by Transmission Electron Microscopes and Differential Mobility Analyzers as well as with theoretical studies of dimer-dominated stochastic coagulation.     

Tunable structural transition and multiferroic properties of the composite thin films through the structural transition of magnetic layer

The Bi_0.9Er_0.1Fe_0.96Mn_0.02Co_0.02O₃/Co_1-xMn_xFe₂O₄ (BEFMCO/CM_xFO) thin films have been deposited by sol-gel method. Structural distortion is observed in the BEFMCO with the appearance of trigonal-R-3m: H in the CM_xFO. The enhanced multiferroic properties, well electrically writable and ferroelectric switching properties are obtained in BEFMCO/CM_xFO thin films. The investigation indicates that the structural transformation of the CM_xFO influences the structure and multiferroic properties of BEFMCO and the interfacial effects between BEFMCO and CM_xFO layers. This transformation and Mn-doping cause the change of carriers, which solves the problem that the magnetic layer exacerbates the ferroelectric properties. It promotes to form the weak local electric field, which causes the weak interface effect, and brings out the weak resistive switching in the BEFMCO/CM_xFO thin films. Therefore, it is believed that the BEFMCO/CM_xFO films can offer a potentially tunable structural transformation of composite films for practical applications.     

SAXS characterization of the Nafion membrane nanostructure modified by radiation cross-linkage

The present study employs small-angle X-ray scattering (SAXS) to investigate the water-swollen structures of two types of Nafion membranes, commercial Nafion 117 membranes and the membranes synthesized from the Nafion precursor, subjected to gamma radiation. The membrane structure can be characterized by two-length scales, comprised the long-range order of lamellar crystalline domains in the matrix and the local order of ionic cluster domains. Both the long-range order lamella and local order cluster in the membranes are significantly affected by the radiation-induced cross-linking. We have extended a local order model to take into account the polydispersity effect, which can more satisfactorily reproduce the ionomer SAXS peak than other existing models. The structural parameters determined from the SAXS model analysis are self-consistent with those obtained from the model-independent Porod analysis. The modified membrane structure by the radiation cross-linking is very helpful for developing a high performance and low cost of direct methanol fuel cells.     

Synthesis and characterization of nylon 6/clay nanocomposites prepared by ultrasonication and in situ polymerization

Nylon 6 nanocomposites were prepared by the in situ polymerization of ε‐caprolactam with ultrasonically dispersed organically modified montmorillonite clay (Cloisite 30B®). Dispersions of the clay platelets with concentrations in the range 1–5 wt % in the monomer were characterized using rheological measurements. All mixtures exhibited shear‐thinning, signifying that the clay particles were dispersed as platelets and forming a “house of cards” structure. Samples with Cloisite concentrations above 2 wt % showed a drop in viscosity between the initial shearing and repeated shearing, indicative of shearing breaking down the initial “house of cards” structures formed on sonication. DMTA measurements of the samples showed an increase in the β‐relaxation temperature with increasing clay concentration. The bending modulus, at temperatures below T_g, showed an increase with increasing clay concentration up to 4 wt %. X‐ray diffraction measurements showed that all nylon 6/Cloisite 30B samples were exfoliated apart from the 5 wt %, which showed that some intercalated material was present. The nylon crystallized into the α‐crystalline phase, which is the most thermodynamically stable form. Preference for this form may be a consequence of the long time associated with the postcondensation step in the synthesis or the influence of the platelets on the nucleation step of the crystal growth. DSC measurements showed a retardation of the crystallization rate of nanocomposite samples when compared with that of pure nylon 6, due to the exfoliated clay platelets hindering chain movement. This behavior is different from that observed for the melt‐mixed nylon 6/clay nanocomposites, which show an enhancement in the crystallization rate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Change in fiber properties due to the heat treatment of nylon 6 tire cords

Nylon 6 is used as a reinforcing material in different rubber products. However, as it is a thermoplastic material, it may undergo some kind of thermal shrinkage during the vulcanization of rubber, which leads to dimensional stability problems in the rubber product. To prevent this, we subjected nylon 6 to some kind of thermal treatment at higher temperatures. During thermal treatment, there was some change in the mechanical properties, shrinkage which may have been correlated with changes in the crystal structure of the polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Structural correlation between crystal lattice and lamellar morphology in the ferroelectric phase transition of vinylidene fluoride-trifluoroethylene copolymers as revealed by the simultaneous measurements of wide-angle and small-angle X-ray scatterings

Intimate correlation has been detected between the crystal structure change and the morphological change of stacked lamellae in the ferroelectric phase transition of vinylidene fluoride-trifluoroethylene (VDF-TrFE) copolymers on the basis of simultaneous measurement of wide-angle (WAXS) and small-angle X-ray scattering (SAXS) patterns in the heating process. The VDF content of copolymers investigated was 65 and 73 mol%. For both of the copolymers, a cold-drawn sample showed the WAXS pattern of the regular low-temperature phase and the four-points SAXS pattern corresponding to the stacking structure of lamellae tilted by about 30° from the draw axis. When the sample was heated above the Curie transition point T_c, the low-temperature phase changed to the conformationally-disordered paraelectric high-temperature phase and the stacked lamellae reoriented into the direction closer to the draw axis. It was also found that the thickness and long period of the lamellae increased remarkably above T_c. These large changes in lamellar stacking mode occurred in parallel with the trans-to-gauche conformational change of the molecular chains in the crystal lattice. In this way, the morphological change was found to relate intimately with the crystal structural change, both of which are considered to be caused commonly as a result of the trans-gauche conformational change and the translational motion of the thermally-activated molecular chains along the chain axis.     

Mechanisms of nucleation and crystal growth in a nascent isotactic polypropylene/poly (ethylene-co-octene) in-reactor alloy investigated by temperature-resolved synchrotron SAXS and DSC methods

The nucleation and lamellar growth mechanisms of nascent isotactic polypropylene/poly(ethylene-co-octene) (N-iPP/PEOc) in-reactor alloy were investigated with temperature-resolved synchrotron small angle X-ray scattering (SAXS), differential scanning calorimeter (DSC) and polarized optical microscopy (POM) methods. We have observed two crystallization peaks (fractionated crystallization behavior) during cooling process in N-iPP/PEOc in-reactor alloy. We also determined that the crystallinities from that two crystallization peaks were dependent on liquid-liquid phase separation (LLPS) time with t^0.10 and t^−0.28, respectively. It was explained that the fractionated crystallization behavior in the N-iPP/PEOc in-reactor alloy system was caused by crystal nucleation occurring in the iPP rich domain by heterogeneous nucleation and at interface of iPP and PEOc rich domains by the fluctuation assisted nucleation. The fluctuation assisted nucleation only occurred at interface of iPP and PEOc domains by concentration fluctuation through the coupling of liquid-liquid spinodal decomposition and the cross-over to crystal nucleation process. Both lamellar crystals formations from heterogeneous and fluctuation assisted nucleation in N-iPP/PEOc were probed by temperature-resolved SAXS during cooling process. Our results provide the physical model for the multiple nucleation and crystal growth mechanisms in the multi-component, multi-phase polymer systems such as in-reactor alloy or blend.     

Morphology and shape memory effect of segmented polyurethanes. Part ?: With crystalline reversible phase

A set of segment polyurethanes were synthesized and were proved to have interconnected, isolated and no hard-segmented domains. It was found that the shape fixity of the polyurethanes decreased with the increase of hard-segment content. The polyurethanes with hard-segment content from 30% to 50% had to be deformed at least to 100% strain to obtain good shape fixity. The segmented polyurethane having no hard-segment domains showed over 90% shape recovery under particular conditions. The segmented polyurethanes having interconnected hard-segment domains showed dramatically decreased shape recovery. The segmented polyurethanes having isolated hard-segment domains showed better shape recovery. When the polyurethanes were heated up to sufficiently high temperature they mostly recovered to their original shape. Stress relaxation would bring decrease to the shape recovery of the polyurethanes, especially to that of the segmented polyurethanes with low hard-segment content of 15% and 20%. For the segmented polyurethanes have isolated hard-segment domains the shape recovery decreased when the deformation amplitude increased from 50% to 200% and stopped decreasing as deformation amplitude increased to 250%. The shape recovery of the segmented polyurethanes could be enhanced nearly to 100% by a pre-deformation treatment.