超高分子量PET溶解过程中的降解

利用超高分子量PET进行溶液纺丝是目前制取高强度高模量PET纤维的一种重要方法。本文对于超高分子量PET在溶解过程中的降解情况进行了研究,认为浓度、温度、时间以及凝固剂是影响其降解的主要因素,并探索了其降解动力学。     

一种特高强超高分子量聚乙烯纤维的制备方法

正本发明提供一种特高强超高分子量聚乙烯纤维的制备方法,采用线性低密度聚乙烯与超高分子量聚乙烯和溶剂共混制备超高分子量聚乙烯纤维,并通超倍拉伸形成高强纤维。将500万～1 000万超高分子量聚乙烯的低溶度溶胀混合物与线性低密度聚乙烯按比例在纺丝溶剂中混合,通过提高超高分子量聚乙烯的分子链长度和添加线性低密度聚乙烯降低纺丝液的黏度,降低螺杆的温度减     

辽化聚酯切片的可纺性研究

通过对辽化PET切片与国内外3种PET切片的分子量分布和常规指数的横向比较,阐明PET切片的分子量分布与PET纤维的抗张强度、拉伸倍数和熔体粘度之间的关系,并通过对辽化PET切片在辽化纤维三厂高速纺丝过程中反映出的问题进行了分析研究。     

超高分子量PET干—湿法纺丝凝固剂的选择

超高分子量PET干—湿法纺丝是制备高强高模纤维的一种重要方法.本文对不同凝固剂的初生纤维的结构性能进行了深入的研究.这些凝固剂分别为甲醇、甲醇/水(体积比为3:1)、甲醇/水(体积比为1:1)、甲醇/水(体积比为1:3)以及水.研究发现,水是最理想的凝固剂.以水为凝固剂纺制的初生纤维是多微孔网络结构,基本上是无定形,拉伸性能好,这样的结构有利于纤维的高倍拉伸.     

高分子量PET溶液纺初生纤维结构和性能

利用高分子量PET进行溶液纺丝是目前制取高强高模PET纤维的一种重要方法.本文主要对不同凝固剂的初生纤维的结构和性能进行了研究,这些凝固剂分别是甲醇、乙醇和丙酮,而甲醇是最为理想的凝固剂,由甲醇凝固的初生纤维结晶度小,晶粒完整性差,并且有较好的拉伸性能,这样的结构有利于纤维的高倍拉伸.     

60PHB/PET共聚酯纤维的结构与性能

将两种不同分子量(特性粘数分别为0.800dL/g和0.534dL/g)的60PHB/PET共聚酯在小型模拟纺丝机上挤压纺丝。通过物性测试对共聚酯纤维进行了结构与性能分析。结果表明:共聚酯纤维具有高结晶、高晶区取向及高分子链取向的高度规整的原纤化结构。这些结构特征赋予纤维具有超高拉伸模量及动态拉伸模量和低延伸、低收缩。     

混杂纤维丝束冲击拉伸性能实验研究

采用自行研制的摆锤式冲击拉伸试验机对玻璃纤维、芳纶纤维、超高分子量聚乙烯纤维和PBO纤维丝束及其混杂丝束进行了冲击拉伸试验.得到混杂纤维丝束断裂吸能和断裂强度随纤维混杂比变化的规律.     

超倍热拉伸PE–UHMW干法纤维的结构与性能

以黏均分子量为600万的超高分子量聚乙烯(PE–UHMW)树脂为原料,通过干法路线纺丝制备出了具有较高拉伸性能的PE–UHMW纤维。测试研究了纤维在热拉伸过程中的力学性能变化,发现纤维在拉伸40倍时断裂强力出现最大值。利用动态扫描量热、X射线衍射、扫描电子显微镜表征了PE–UHMW纤维在拉伸过程中结构变化,分析了结构变化对力学性能的影响,发现过高的拉伸倍数反而会破坏纤维的结晶结构从而导致断裂强力的下降。最后对热拉伸中纤维微观结构变化机理进行了推导。     

纳米超高分子量聚乙烯研制成功

2006年6月21日,香港科技大学宣布首次成功在超高分子量聚乙烯塑料中加入纳米碳管,使这种新型纳米合成纤维的拉伸强度比同等粗细的高强度钢丝高出8倍,大大提升了这种新型高强纤维的防弹功能。这项技术为超高分子量聚乙烯塑料开拓了更具市场效应的前景。(中塑机网)纳米超高分子量     

超高分子量PET的固相聚合

本文采用分段固相聚合的方法合成了特性粘度达1.5以上的超高分子量PET树脂。研究了聚合温度、聚合时间、聚合体颗粒度、搅拌速度、真空度等对固相聚合速度的影响,初步探讨了固相聚合机理,确立了较佳的工艺路线,为纺制高强PET纤维打下了基础。     

超高分子质量聚酯(UHMW-PET)纤维可牵伸性能研究

研究了超高分子质量聚酯 (UHMW-PET)特性粘数及纺丝溶液浓度对初生纤维可牵伸性能 (EDRmax)的影响。结果表明 :在给定分子质量下 ,存在一个最适合纺丝的浓度 ,在该浓度下 ,纤维具有最大的可牵伸倍率 ,此时纤维中大分子的缠结中密度处于最有利于拉伸的状态 ,并且随着分子质量的增加 ,适合纺丝的最佳浓度反而下降 ,但是在该浓度下 ,初生丝的拉伸性能都随着分子质量的增加而增加。     

Swollen-state polymerization of poly(ethylene terephthalate) in fibre form

The swollen-state polymerization of poly(ethylene terephthalate) in fibre form was performed in hydrogenated terphenyl as the swelling solvent. Ultra-high-molecular-weight poly(ethylene terephthalate) (CHMW-PET) fibre with an intrinsic viscosity of 3–4dl g⁻¹ (M_n = 2–3 × 10⁵) was obtained. The polymerization rate of as-spun PET fibres in the swollen state was greater than that of PET granules in the swollen state. It was clarified that the polymerization rate was related to the chain mobility of the starting materials. The chain mobility was influenced by various conditions, such as changing rigidity of the segments during copolymerization, the chain orientation of the starting fibre before swollen-state polymerization and the temperature of pretreatment with the solvent. Pretreatment with solvent before polymerization was effective in increasing the chain mobility. The relation between chain mobility and polymerization rate was examined by wide-angle X-ray diffraction, density, differential scanning calorimetry, solvent content and viscoelastic measurements. Undrawn UHMW-PET fibres could be drawn 10 times or more by the zone drawing technique in spite of their high crystallinity, and the drawn fibre showed high tensile strength (12 g d⁻¹) and high modulus (240 g d⁻¹).     

超高分子量聚乙烯熔纺丝的拉伸行为及其对结构性质的影响

采用石蜡作稀释剂，用增塑熔纺的方法制备高强高模聚乙烯纤维（UHMWPE），弥补了传统凝胶纺存在的生产周期长、生产效率低的不足。还借助扫描电子显微镜（SEM）、热分析（DSC）、广角X射线衍射（WAXD）、声速等手段研究了UHMWPE熔纺丝在超拉伸过程中结构性能的变化。     

Influence of orientation on polyester fibres

The technological applications and the associated molecular mechanisms of various levels of orientation in polyester fibres are discussed. The inherent birefringence of these fibres is high and therefore the orientation is easily measurable, while their behaviour is very sensitive to small changes in orientation. In particular, practical properties such as strength, productivity and ease of bulking are very dependent on the spun yarn orientation before the drawing operation takes place, but for completely different reasons. Polyester fibres can be pretreated in terms of orientation in such a way that an extremely high spontaneous extension can be obtained, a property which can be used for bulking. It is shown that variations in low levels of orientation can have profound industrial implications.     

涤纶短纤维后拉伸点的位置及其控制

介绍了Inventa的涤纶短纤维生产后拉伸工艺技术,其特点是将拉伸点控制在拉伸辊的表面上而非像通常那样控制在拉伸介质里。拉伸点后丝束与辊面间由于速度差别而产生快速摩擦,从而产生热板效应,使丝束的拉伸条件更柔和、更优越,拉伸丝束更均匀,并可减少最终产品出现因拉伸不足而形成的疵点。这种工艺的关键是丝束的拉伸点必须出现在一道拉伸机第6辊上喷淋油剂稍后的地方,且尽可能处于一条狭线上。通过改变拉伸点前后丝束的加热条件,可方使且有效地调整拉伸点出现的位置,从而将拉伸点控制在期望出现的位置上。这种工艺技术广泛应用于欧洲涤纶短纤维生产上。     

Orientation and structure development in melt-spun Nylon-6 fibres

A network model is applied to describe the deformation behaviour of melt-spun Nylon-6 fibres obtained at different spinning and drawing conditions. The network draw ratio is determined from analysis of true stress-strain curves and correlated with fibre orientation. From this analysis it appears that the deformation behaviour of Nylon-6 fibres adheres to a pseudo-affine mechanism. The results are discussed in terms of the semicrystalline nature of Nylon-6 fibres. By means of on-line birefringence measurements, wide angle X-ray scattering (WAXS) and solid-state NMR, it is shown that the crystalline and amorphous phases in Nylon-6 respond in a different way to network deformation. In the spin line, an affine (rubber-like) deformation mechanism is observed and this rubber-like network behaviour is transferred to the amorphous phase. After winding and conditioning of the spun fibres, a crystalline phase with relatively high orientation is formed which deforms according to a pseudo-affine mechanism upon further stretching.     

Technological Aspects of Orientational Strengthening of Poly(Ethylene Terephthalate). Modern Schemes for Production of High-Strength Polyester Fibres

Theoretical and technological aspects of orientational strengthening of polyester fibres are examined. High strength of polyester fibres is attained by the combination of the high molecular weight of poly(ethylene terephthalate) with stage-wise (in several stages) drawing. Current schemes for production of high-strength polyester fibres are reported.     

Spinning of high molecular weight polyethylene solution and subsequent drawing in a temperature gradient

Summary The spinning and drawing of high molecular weight polyethylene solution forming ultra-high strength fibres has been studied and occurrances on the molecular level are discussed. The fibre properties were found to be strongly influenced by the drawing stress and the temperature conditions.