Mechanism of Polymer Crystallization and Control of Fine Structure under Molecular Orientation

分子取向下聚合物结晶机理及精细结构控制

• 批准号: 12127202
• 负责人: OKUI Norimasa
• 金额: $ 19.84万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12127202/
• 关键词: Ordered Structure; Light Scattering; High Speed Melt Spinning; Orientation Crystallization; Birefringence; Relaxation of Molecular Orientation; Crystallization Rate; Nucleation Rate; 高分子; 結晶化; 高次構造; 分子配向; 高速紡糸; 溶融紡糸; 拡散

Molecular weight (MW) dependence of physical properties is one-of the most common characteristics in polymeric materials. For example, melt viscosity of polymer shows remarkable MW dependence and can be scaled and expressed as a 3.4 power of MW for entangled polymer chains. Also the influence of MW on polymer crystallization rate has been the most interesting subject. We studied on molecular weight dependence of crystal nucleation rate (I) and crystal growth rate for various polymers. The temperature dependence of I and G showed bell-shaped curves showing clear maximum points of Imax and Gmax. Imax and Gmax showed remarkable MW dependence. The plots of the reduced growth rate (G/Gmax) and the reduced nucleation rate (Inmax) showed a single master curve without MW dependence. Imax and Gmax are characteristic references to nucleation and crystal growth rate behaviors, respectively. The MW dependence of Imax and Gmax are scaled and expressed as I and -0.5 power of MW, respectively for a c … More hain folding crystallization.Crystallization rate of Poly(carbonate) (PC) in general is very slow, however its rate is accelerated by polymer blending with poly(ethylene oxide) (PEO). The crystallization of PC in the PC/PEO blends is completed within several seconds. During crystallization of the blends, spinodal decomposition was observed and spherulite of PC was observed in PC rich phase. The crystallization of PC was controlled by up-hill diffusion during liquid-liquid phase separation in the polymer blends.Bi-and uni-axial drawing of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6 naphthalene dicarboxylate) (PEN) were performed at various strain rates and temperatures. On-line measurements of drawing stress and birefringence were carried out under several drawing conditions. The stress-optical rule (SOR) was applicable at low birefringence, and the stress-optical coefficient obtained for drawing process was similar to the reported values. Flow drawings of PET and PEN were caused at relatively high drawing temperature and low strain rate. The SOR was also applicable in flow drawing conditions. To analyze the network structure of each sample that has low crystallinity and low birefringence, the entanglement density Nc of drawn films was analyzed from the measurement of heat shrinkage and shrinkage stress applying the rubber elasticity theory for Gaussian chain. In the drawing of PEN. Nc value of drawn sample was lower when the drawing temperature was higher and strain rate was lower.Structure formation of stereo complex (racemate) polylactides fibers by high-speed melt spinning and subsequent drawing and annealing process was investigated. Distinct crystalline reflections appeared in WAXD patterns of as-spun fibers above 4 km/min. The crystal modification was co-existence of alpha-form and stereo complex crystals, and reflection intensity of stereo complex crystal increased with an increase in the take-up velocity and a decrease in the throughput rate and spinning temperature. The crystalline reflections of annealed high-speed spun fibers showed higher orientation and richer stereo complex crystallites than the fibers obtained by drawing and annealing low-speed spun fibers. From the diameter profile measurement of the spin-line, it was found that higher crystallization temperature in the spinning process leads to the preferred formation of stereo complex crystals. Less

相对分子质量(MW)与物理性质的关系是聚合物材料最常见的特性之一。例如，聚合物的熔体粘度表现出显著的相对分子质量依赖性，对于缠绕的高分子链，可以用3.4倍的相对分子质量来衡量和表示。此外，分子量对聚合物结晶速率的影响也一直是人们最感兴趣的课题。我们研究了不同聚合物的结晶成核速率(I)和晶体生长速率(I)的相对分子质量关系。I和G随温度变化呈钟形曲线，Imax和Gmax峰值明显。IMAX和GMAX表现出显著的MW依赖性。折合生长速率(G/Gmax)和折合成核速率(Inmax)曲线呈单一主曲线，不依赖于相对分子质量。IMAX和GMAX分别是成核和晶体生长速率行为的特征参考。对于c…，Imax和Gmax的mW依赖关系被缩放并分别表示为mW的I次方和-0.5次方聚碳酸酯(PC)的结晶速度一般很慢，但聚合物与聚环氧乙烷(PEO)共混可加快其结晶速度。PC/PEO共混物中PC的结晶在几秒钟内完成。在共混物的结晶过程中，共混物发生了调幅分解，在富PC相中观察到了PC的球晶。共混物中液-液相分离过程中PC的结晶受上坡扩散控制。在不同应变速率和温度下，对聚对苯二甲酸乙二酯(PET)和聚2，6-萘二甲酸乙二醇酯(PEN)进行了双向拉伸和单轴拉伸。在不同的拉伸条件下，进行了拉拔应力和双折射的在线测量。应力-光学规则(SOR)适用于低双折射，拉伸过程中得到的应力-光学系数与文献报道的值相似。PET和PEN在较高的拉伸温度和较低的应变速率下产生流动拉伸。SOR也适用于引流条件。为了分析低结晶度和低双折射样品的网络结构，应用高斯链橡胶弹性理论，通过热收缩和收缩应力的测量，分析了拉伸薄膜的纠缠密度Nc。在钢笔的画中。拉伸温度越高、应变速率越低，拉伸样品的Nc值越低。研究了高速熔融纺丝和后续拉伸、退火工艺对立体复合(外消旋体)聚乳酸纤维结构的形成。在4 km/min以上的初生纤维的WAXD花样中出现了明显的结晶反射。结晶改性为α-晶型和立体复合晶体共存，立体复合晶体的反射强度随卷绕速度的增加、吞吐速率的降低和纺丝温度的降低而增大。与拉伸和退火法相比，高速纺丝纤维的结晶反射显示出更高的取向度和更丰富的立体复合晶。通过对纺丝线直径分布的测量，发现纺丝过程中较高的结晶温度有利于立体络合物晶体的形成。较少

项目成果

H.H.Cho,K.H.Kim,H.Ito and T.Kikutani: "Fine-Structure and Physical Properties of Polyethylene Fibers in High-Speed Spinning I Effect of Melt-Flow Rate in the High-Density Polyethylene"J.Appl.Polym.Sci.. 77. 1182-1194 (2000)

H.H.Cho、K.H.Kim、H.Ito 和 T.Kikutani：“高速纺丝中聚乙烯纤维的细结构和物理性能 I 高密度聚乙烯熔体流动速率的影响”J.Appl.Polym.Sci

占部宏生,伊藤浩志,鞠谷雄士,奥居徳昌: "ポリプロピレンの高速溶融紡糸過程における分子配向形成のオンライン計測"成形加工. 12(11). 729-735 (2000)

Hiroshi Urabe、Hiroshi Ito、Yuji Maritani、Norimasa Okui：“聚丙烯高速熔融纺丝过程中分子取向形成的在线测量” 12(11) 729-735 (2000)。

S.Umemoto, N.Okui: "Master curve of crystal growth rate and its corresponding state in polymeric materials"Polymer. 43. 1423-1427 (2002)

S.Umemoto，N.Okui：“聚合物材料中晶体生长速率及其相应状态的主曲线”聚合物。

T.Kikutani: "Dynamics and Evolution of Structure in Fiber Extrusion"J.Appl.Polym.Sci.. 83. 539-558 (2002)

T.Kikutani：“纤维挤出结构的动力学和演化”J.Appl.Polym.Sci.. 83. 539-558 (2002)

S.Umemoto: "Molecular weight dependence of primary nucleation rate of PESU"J.Macromolecular Sci.. B42. 421-430 (2003)

S.Umemoto：“PESU 初级成核速率的分子量依赖性”J.Macromolecular Sci.. B42。