TIE MOLECULAR CONCENTRATION EFFECTS ON THE CRYSTAL ORIENTATION BEHAVIORS IN THE MISCIBLE PVDF/ACRYLIC POLYMER BLENDS
It is generally accepted that the presence of molecular connections between different crystallites, namely, tie molecules, takes the key role in determining the mechanical performance of semicrystalline polymers. If the tie molecules did not exist, the polymer crystallites would only be held together by van de Waals or hydrogen bond interactions. These physical interactions are obviously too weak to provide sufficient strength for connecting adjacent crystallites under stress; and this results in the macroscopic brittleness and low strength of the material. The formation of tie molecules has been attributed to the random coil dimension in the molten state being larger than the thickness of crystallite formed in the solidified state after crystallization. Several crystalline lamellae can grow within the sphere of gyration of a chain as long as the molecular chain is sufficiently long. Therefore, the long chain molecule can cross the amorphous layer and provide the mechanical bridging of the adjacent crystalline lamellae. Because of the great importance of the tie molecules for the properties of semicrystalline polymers, numerous investigations have been carried out to assess the concentration of tie molecules and to evaluate the effects of the concentration on the mechanical properties of materials. Although the concentration of tie molecules can be adjusted by changing the molecular structure and/or varying the crystallization conditions, the polymer crystals with controlled tie molecules are difficult to prepare from melt for high molecular polymers due to the molecular entanglement in the bulk state.
Yongjin Li
Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIS), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565 Japan
国际会议
PP’2010，Jinan International Symposium on Polymer Physics(2010济南国际高分子物理学术研讨会)
济南
英文
52
2010-06-06（万方平台首次上网日期，不代表论文的发表时间）