Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM...Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM）. The characteristic length L was defined as the size of particles of the dispersed phase in blends. Different fractal dimensions, Df and Din, were introduced to study the distribution width of phase dimensions in the dimensionless region and the uniformity of the spatial distribution of particles, respectively. The results showed that the average characteristic length Lm and Df increase as the volume fraction of the dispersed phase increases, when the volume fraction of the dispersed phase is lower than 50%. In other words, the size of particles increases and their distribution in the dimensionless region becomes more uniform. Meanwhile, the uniformity of the spatial distribution becomes more perfect as the volume fraction increases. At a certain composition, Lm decreases in the initial stage of the mixing and levels off in the late stage. In the initial stage, Df becomes large rapidly with the process of blending, which means that the distribution of L in the dimensionless region becomes more uniform. Meanwhile, the spatial distribution tends to be ideal rapidly in the early stage and fluctuates in a definite range in the late stage of the mixing.展开更多
The general strategy to construct D-A type conjugated polymers is alternating copolymerization of electron-donating(D)monomer and electron-accepting(A)monomer.In this article,we report a new strategy to develop D-A ty...The general strategy to construct D-A type conjugated polymers is alternating copolymerization of electron-donating(D)monomer and electron-accepting(A)monomer.In this article,we report a new strategy to develop D-A type conjugated polymers,i.e.first fuse the D and A units into a polycyclic structure to produce a building block and then polymerize the building block with another unit.We develop a new building block with ladder structure based on B←N unit,B←N bridged dipyridylbenzene(BNDPB).In the skeleton of BNDPB,one diamine-substituted phenylene ring(D unit)and two B←N-linked pyridyl rings(A unit)are fused together to produce the polycyclic structure.Owning to the presence of intramolecular D-A character,the building block itself exhibits narrow bandgap of 1.74 eV.The conjugated polymers based on BNDPB show unique electronic structures,i.e.localized HOMOs and delocalized LUMOs,which are rarely observed for conventional D-A conjugated polymers.The polymers exhibit smaller bandgap than that of the building block BNDPB and display near-infrared(NIR)light absorption(λabs=ca.700 nm).This study thus provides not only a new strategy to design D-A conjugated polymers but also a new kind of building block with narrow bandgap.展开更多
BaTiO3/ Interpenetrating Polymer Networks (IPNs) composites were prepared by combination of BaTiO3 nanocrystal in tetragonal system and polyurethane(PU)/ unsaturated polyester (UP) interpenetrating polymer networks (I...BaTiO3/ Interpenetrating Polymer Networks (IPNs) composites were prepared by combination of BaTiO3 nanocrystal in tetragonal system and polyurethane(PU)/ unsaturated polyester (UP) interpenetrating polymer networks (IPNs). The tetra gonal nanocrystalline BaTiO3 was obtained by hydrothermal process and calcinatio n at 1 200 ℃. The prepared materials were polarized with high voltage a nd small current, and protected by silicon oil. The morphology of BaTiO3/ IPNs and the effect of combination of BaTiO3 on the damping behavior of IPNs were stu died. The relationship between damping performance and dielectric charater was a lso discussed in terms of dielectric constant and dielectric loss measured. The results show that the areas under loss modulus (E″) and the values of loss fact ors (tanBaTiO3 into IPNs system. The m aximum value of E″ increased above 100 MPa compared with pure IPNs and the exte nt increased more remarkably after polarizing process. The main and shoulder pea k of tand the temperatu re ranges of tan℃. Moreover, through polarizing proc ess, the composites exhibited synergistic action caused by elastomeric damping, interfacial abrasive damping and piezoelectric damping mechanisms. The relations hip study of damping property and dielectric characters showed that the temperat ure ranges exhibited excellent consistency of maximum dielectric loss and modulu s with damping loss factor.展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 50390090).
文摘Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM）. The characteristic length L was defined as the size of particles of the dispersed phase in blends. Different fractal dimensions, Df and Din, were introduced to study the distribution width of phase dimensions in the dimensionless region and the uniformity of the spatial distribution of particles, respectively. The results showed that the average characteristic length Lm and Df increase as the volume fraction of the dispersed phase increases, when the volume fraction of the dispersed phase is lower than 50%. In other words, the size of particles increases and their distribution in the dimensionless region becomes more uniform. Meanwhile, the uniformity of the spatial distribution becomes more perfect as the volume fraction increases. At a certain composition, Lm decreases in the initial stage of the mixing and levels off in the late stage. In the initial stage, Df becomes large rapidly with the process of blending, which means that the distribution of L in the dimensionless region becomes more uniform. Meanwhile, the spatial distribution tends to be ideal rapidly in the early stage and fluctuates in a definite range in the late stage of the mixing.
基金supported by the National Natural Science Foundation of China (21625403, 21822507, 21875244, 21761132020, 21574129)National Key Research and Development Program of China (2018YFE0100600)+2 种基金funded by MOST and Strategic Priority Research Program of CAS (XDB12010200)Youth Innovation Promotion Association of CAS (2017265)State Key Laboratory of Supramolecular Structure and Materials in Jilin University (sklssm201905)
文摘The general strategy to construct D-A type conjugated polymers is alternating copolymerization of electron-donating(D)monomer and electron-accepting(A)monomer.In this article,we report a new strategy to develop D-A type conjugated polymers,i.e.first fuse the D and A units into a polycyclic structure to produce a building block and then polymerize the building block with another unit.We develop a new building block with ladder structure based on B←N unit,B←N bridged dipyridylbenzene(BNDPB).In the skeleton of BNDPB,one diamine-substituted phenylene ring(D unit)and two B←N-linked pyridyl rings(A unit)are fused together to produce the polycyclic structure.Owning to the presence of intramolecular D-A character,the building block itself exhibits narrow bandgap of 1.74 eV.The conjugated polymers based on BNDPB show unique electronic structures,i.e.localized HOMOs and delocalized LUMOs,which are rarely observed for conventional D-A conjugated polymers.The polymers exhibit smaller bandgap than that of the building block BNDPB and display near-infrared(NIR)light absorption(λabs=ca.700 nm).This study thus provides not only a new strategy to design D-A conjugated polymers but also a new kind of building block with narrow bandgap.
文摘BaTiO3/ Interpenetrating Polymer Networks (IPNs) composites were prepared by combination of BaTiO3 nanocrystal in tetragonal system and polyurethane(PU)/ unsaturated polyester (UP) interpenetrating polymer networks (IPNs). The tetra gonal nanocrystalline BaTiO3 was obtained by hydrothermal process and calcinatio n at 1 200 ℃. The prepared materials were polarized with high voltage a nd small current, and protected by silicon oil. The morphology of BaTiO3/ IPNs and the effect of combination of BaTiO3 on the damping behavior of IPNs were stu died. The relationship between damping performance and dielectric charater was a lso discussed in terms of dielectric constant and dielectric loss measured. The results show that the areas under loss modulus (E″) and the values of loss fact ors (tanBaTiO3 into IPNs system. The m aximum value of E″ increased above 100 MPa compared with pure IPNs and the exte nt increased more remarkably after polarizing process. The main and shoulder pea k of tand the temperatu re ranges of tan℃. Moreover, through polarizing proc ess, the composites exhibited synergistic action caused by elastomeric damping, interfacial abrasive damping and piezoelectric damping mechanisms. The relations hip study of damping property and dielectric characters showed that the temperat ure ranges exhibited excellent consistency of maximum dielectric loss and modulu s with damping loss factor.
