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In the present work, we used molecular dynamics simulations to study the effects of carbon nanotube (CNT) contents on stretch-induced crystallization behavior in CNT filled polyethylene systems. During high-temperature stretching, the stretching is responsible for the orientation of CNTs, which then facilitates segment orientation and conformational transition from the gauche-conformation into the trans-conformation in interfacial regions. The systems with higher CNT contents have a higher degree of orientation and higher contents of trans-conformation during stretching, resulting in the formation of more precursors. During subsequent crystallization, the initial crystallization rate increases with the increase of the CNT content due to the increase in precursor contents in interfacial regions. However, after the CNT content exceeds a certain value, a filler network would be formed by CNTs, which can restrict chain movements and then lead to a decrease in the overall crystallization rate in the systems with high CNT contents. [ABSTRACT FROM AUTHOR]

Grafting density and confinement scale of the nano‐area are significant elements affecting the crystallization behavior of polymers. In this work, the crystallization processes of confined and unconfined polymer systems with different grafting density were systematically studied by MC simulation. The results show that when the grafting density of confined systems is low, the crystallization rate is faster and the final crystallinity is higher. However, the crystallization ability is reduced for higher grafting density. We found that for this confined system, the segmental density of interfacial region is larger, and the movement of chain segment is lower. Due to the higher grafting density, the crowding effect of polymer chains is strong, which leads to the intermolecular nucleation. The critical nucleation free energy barrier is higher. Moreover, only homogeneous nucleation occurs in confined polymer systems. With the increasing grafting density, the crystals change from lying on the substrate surface to being perpendicular to the substrate surface in unconfined polymer systems. The crystals are mainly lying on the substrate surface in confined polymer systems. These simulation results are helpful to understand the microscopic mechanism of crystallization behaviors of polymer nanocomposites and provide a theoretical basis for the design of nanocomposites with excellent physical properties. [ABSTRACT FROM AUTHOR]

Crystallisation of polymer chains grafted onto a nanoparticle and the effects of grafting density and polymer–nanoparticle interaction were investigated by Monte Carlo simulations. The increase of grafting density leads to the improvements of nucleation ability and the increase in both melting point and final crystallinity. Moreover, the increase of interfacial interaction can lead to the changes of nucleation mode from homogenous nucleation to heterogeneous nucleation, accelerating the nucleation process. To explain the increase of melting point induced by grafting, a prediction of theoretical formula is established, which indicates that the melting point is related to the deformation and concentration of grafted polymer chains. Our findings develop a thermodynamic background for the crystallisation of grafted polymer systems and explain the corresponding experimental results, which has a certain guiding implication for the design, preparation and application of polymer nanocomposites. [ABSTRACT FROM AUTHOR]

Understanding crystallization mechanism of random copolymers is beneficial for the design and development of new polymeric materials. We performed dynamic Monte Carlo simulations to investigate the crystallization behaviours of random copolymers in polymer solutions induced by one-dimensional nanofiller. The effects of comonomer content on crystallinity and crystalline morphology were studied in detail. In the copolymers with relatively low comonomer contents, the final absolute crystallinity is independent of comonomer contents, while in the copolymers with relatively high comonomer contents the final absolute crystallinity decreases with increasing comonomer contents. In addition, the one-dimensional nanofiller can induce the formation of nanohybrid shish-kebab structures in the copolymers with low comonomer contents. However, in the copolymer with very high comonomer content, the presence of a large number of comonomers with no ability of parallel arrangements hinders the formation of nanohybrid shish-kebab structures. [ABSTRACT FROM AUTHOR]