Summary: The crystallization behavior of a poly(butylene succinate)‐based ionomer (PBSi) was analyzed by morphological observations and synchrotron small‐angle X‐ray scattering (SAXS) experiments. The spherulitic morphology of PBSi is composed of irregular lamellae propagating outwards from the center with ionic clusters isolated from the crystalline lamellae. Synchrotron radiation SAXS profiles revealed that the re‐crystallization during heating process was effectively retarded with increasing ionic content, suggesting that the presence of ion aggregates affects the extent of diffusion of chains towards crystallization.
PBSi‐3 was isothermally crystallized at 85 °C for 30 min (400×). The spherulites of PBSi‐3 showed an irregular ringed pattern without a distinct center of spherulite. 相似文献
Polymerizations of methyl methacrylate with (α‐diimine)nickel(II)/methylaluminoxane (MAO) and (pyridyl bis(imine))iron(II) and (pyridyl bis(imine))cobalt(II)/MAO are reported. Effects of structural variation of the ligand on the activities of catalysts and polymer microstructure are described. The catalyst systems gave syndio‐rich poly(methyl methacrylate). The α‐diimine system showed much higher activity than the pyridyl bis(imine) systems under similar polymerization conditions.
The engine combustion network (ECN) Spray A is modelled using the Reynolds-averaged Navier–Stokes-transported probability density function (RANS-TPDF) approach to validate the application of a new multiple mapping conditioning (MMC) mixing model to multiphase reactive flows. The composition TPDF equations are solved using a Lagrangian stochastic approach and the spray is modelled with a discrete particle approach. The model is first validated under non-reacting conditions (at 900 K) using experimental mixture-fraction data. Reactive simulations are then performed for three different ambient temperatures (800, 900, 1100 K) and oxygen concentrations (13, 15, 21%) at an ambient density of 22.8 kg/m3. The MMC mixing model is compared with the interaction by exchange with the mean (IEM) mixing model. The ignition delay predictions are not sensitive to the mixing model and are predicted well by both the mixing models under all the tested ambient conditions. The IEM model overpredicts the flame lift-off length (FLOL) at high temperature and high oxygen conditions with a mixing constant . The MMC model with and a target correlation coefficient between the mixture fraction and a reference variable used to condition mixing predicts good FLOL under all the conditions except 800 K. It is demonstrated that the lift-off length is controllable by changing the target correlation coefficient, while C? and therefore the mixing fields are held fixed. In comparison to the MMC model, the IEM model predicts a higher variance of temperature conditioned on mixture fraction near the flame base owing to its lacking the property of localness. The mixing distance between the notional TPDF particles in the composition space is also higher with the IEM model and it is demonstrated that by changing rt, different levels of mixing locality can be achieved. 相似文献
Herein, the effect of dispersion uniformity of multi-walled carbon nanotube (MWCNT) on the thermal conductivity of poly(dimethyl siloxane) (PDMS) composites was investigated by comparing experimentally obtained and calculated results based on simple models. Two different MWCNTs, i.e., raw and oxidized/masterbatched MWCNTs, were used and compared. For raw MWCNT, the dispersion in PDMS was poor, resulting in the significant reduction in the aspect ratio of MWCNT. However, for composites using masterbatched MWCNT, the thermal conductivity was always about 10% greater than those prepared with raw MWCNT and the aspect ratio calculated by the model equation was also 1.7 times greater. Above 1.5 phr masterbatched MWCNT concentrations, the aspect ratio of 430 was maintained. Finally, the results suggest that the thermal conductivity can be correlated with the degree of dispersion and aspect ratio obtained from the model equation used. 相似文献
Ni/NiO core/shell nanoparticles having high affinity with polyhistidine were synthesized by decomposition of a Ni surfactant complex followed by air oxidation. Ni/NiO nanoparticles showed selective and efficient binding to histidine-tagged proteins and easy separation by using a magnet. These provided a more convenient way to efficient purification of histidine-tagged proteins compared with the conventional Ni-NTA complex-bound resins and microbeads. 相似文献
A new reducing system comprising Pd(OAc)2 and NaBH4 in methanol to generate palladium nanoparticles has been efficiently utilized to reduce a variety of unsaturated carbonyl compounds. These were reduced to their corresponding saturated alcohols and fully saturated compounds in selected cases. This protocol presents alternative and mild reaction conditions for reduction. 相似文献