Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polym...Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope（SEM）and optical microscope（OM）observations,respectively. The differences in the positive temperature coefficient（PTC）effects of the composites were mainly attributed to inter-fiber contact ability.The elimination of the negative temperature coefficient（NTC）effect for CF/PVDF composite was because of an increase in the viscosity of the polymer matrix.With the same filler content,CF could be more effective,to eliminate the NTC effect when compared with GF.Addition of 2%CF（mass fraction）in the PVDF composite with 7%GF（mass fraction）could effectively eliminate the NTC phenomenon of the composite.展开更多
The dispersing process of polyacenic semiconductor(PAS) in polyethylene(PE) was simulated by using molecular dynamics(MD) methods. The results show that this process can be divided into three stages. In the first stag...The dispersing process of polyacenic semiconductor(PAS) in polyethylene(PE) was simulated by using molecular dynamics(MD) methods. The results show that this process can be divided into three stages. In the first stage, PAS particles in the crystal region of PE are expelled to the amorphous region; in the second stage, PAS particles aggregate due to small surface areas and PE chains are adjusted continuously, which makes the crystal region complete; PAS particles are separated from each other and the total energy increases in the third stage. During the whole dispersing process, PAS particles are more stable in the amorphous region than in the crystal region. All the simulation results are in good agreement with the experimental results.展开更多
基金the National Natural Science Foundation of China(Nos.20771030 and 20671025).
文摘Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope（SEM）and optical microscope（OM）observations,respectively. The differences in the positive temperature coefficient（PTC）effects of the composites were mainly attributed to inter-fiber contact ability.The elimination of the negative temperature coefficient（NTC）effect for CF/PVDF composite was because of an increase in the viscosity of the polymer matrix.With the same filler content,CF could be more effective,to eliminate the NTC effect when compared with GF.Addition of 2%CF（mass fraction）in the PVDF composite with 7%GF（mass fraction）could effectively eliminate the NTC phenomenon of the composite.
文摘The dispersing process of polyacenic semiconductor(PAS) in polyethylene(PE) was simulated by using molecular dynamics(MD) methods. The results show that this process can be divided into three stages. In the first stage, PAS particles in the crystal region of PE are expelled to the amorphous region; in the second stage, PAS particles aggregate due to small surface areas and PE chains are adjusted continuously, which makes the crystal region complete; PAS particles are separated from each other and the total energy increases in the third stage. During the whole dispersing process, PAS particles are more stable in the amorphous region than in the crystal region. All the simulation results are in good agreement with the experimental results.
