大直径聚苯硫醚单丝的后拉伸性能研究

测试了不同拉伸工艺下聚苯硫醚(PPS)单丝的力学性能,分析了拉伸后单丝的结构,以研究拉伸倍率、拉伸温度及拉伸级数对PPS单丝的结构和力学性能的影响,结果表明由于PPS的玻璃化温度较高,实验中的单丝一级拉伸温度应在115℃左右,拉伸倍率为4.2,二级拉伸比一级拉伸的抗拉强度高。     

中空硬弹聚丙烯单丝超分子结构和物理—机械性能的研究

研究了单、双两种组分的中空硬弹聚丙烯单丝在不同纺丝温度和拉伸倍数下的超分子结构及性质变化,并与硬弹、普通中空聚丙烯单丝进行了比较。发现单、双两种组分的中空硬弹聚丙烯单丝与普通中空聚丙烯单丝在结构和性质上有很大的差别,而与硬弹聚丙烯单丝基本相似。随着拉伸倍数的增加,单、双两组分的中空硬弹聚丙烯单丝,其取向,断裂强度均有一个最小值;回弹率有一最大值;单丝的晶轴取向与硬弹处理有关,而晶型变化与硬弹处理无直接联系,结晶度高于普通单丝。纺丝温度低,有利于取向和弹性的提高。     

热定形超喂率对大直径涤纶单丝结构与性能的影响

探究了在热定形过程中超喂率对大直径涤纶单丝结构与力学性能的影响。对制备的单丝进行了拉伸和热收缩性能测试,并通过广角X射线衍射、小角X射线散射及声速取向等方法对微观结构进行了表征。结果表明,随着超喂率的降低,单丝在热定形中受到的张力增大,有利于链段沿着拉伸方向排入晶格,结晶度小幅上升,而在纤维径向上的晶粒尺寸及片晶直径减小。超喂率对单丝非晶区结构影响显著,低超喂率下获得的单丝内部形成的非晶区分子链的取向程度大且含量低,导致纤维断裂强度及初始模量较大且断裂伸长低。此外,低超喂率条件下单丝纤维非晶区取向高,致使热收缩率较大。     

中空硬弹聚丙烯单丝微孔结构的研究

本文采用定性和定量的测试手段,着重研究了拉伸倍数和中空硬弹聚丙烯单丝中微孔结构的关系。试验发现,该单丝的微孔结构与拉伸倍数有关。在一定的拉伸倍数下,其微孔不仅尺寸大、数量多,而且还能部分沟通纤维壁。在与其它几种聚丙烯单丝的比较中,发现该单丝不论在微孔的数量和尺寸上,或者是沟通纤维壁的性能上,都大大超过了普通硬弹聚丙烯单丝。其中双组分中空硬弹聚丙烯单丝又优于单组分中空硬弹聚丙烯单丝。     

3＋9＋15×0.175交互捻钢丝帘线拉伸齐断的研究

通过对3＋9＋15×0.175钢丝帘线各层单丝的理论应力进行分析,并对解捻单丝的实际破断力进行测试,分析钢丝帘线拉伸不齐断的原因。结果表明,通过3＋9层使用高破断力单丝,使捻制后3＋9层单丝的破断力与外层15根单丝相近,从而增大了3＋9＋15×0.175钢丝帘线拉伸齐断的几率。     

生产硬弹性PP单丝的关键技术

随着塑料制刷业的兴起,硬弹性PP单丝(φ0,8～1mm)的需求量越来越大.由于用途上特殊的硬弹性需求,其生产技术也不同一般.目前,国内仅有几家企业能够生产,本文根据生产实践,研究讨论了硬弹性单丝的生产技术.1 硬弹性PP单丝的特殊性与通常单丝相比,硬弹性PP单丝直径大且具有较高的弯曲刚性和弯曲变形回弹性.已知PP单丝的硬弹性受分子量大小,结晶度高低,球晶完善程度,单丝内部空穴多少(大小)等因素影响,除此之外在很大程度上还取决于PP分子取向度.经验表明PP拉伸比≥19时,单丝的硬弹性达到理想范围.如此大的拉伸比,要求用较粗的拉伸条(如φ1mm单丝需要用φ4.3～4.5mm粗的拉伸     

工艺条件对热塑性聚酯弹性体单丝回弹性能的影响

采用熔融纺丝方法制备热塑性聚酯弹性体单丝,利用强伸度仪研究空气冷却距离、拉伸倍数、热定形方式、热定形温度对热塑性聚酯弹性体单丝弹性回复性能的影响,利用DSC、广角X-射线衍射仪测定其结构及结晶度的变化。结果表明:随着空气冷却距离和拉伸倍数的增加,单丝的弹性回复率提高;紧张热定形较松弛热定形单丝的弹性回复好;随着热定形温度升高,弹性回复率先升高后降低。     

高性能单丝技术的发展

阐述了国外高性能单丝的品种、用途及其技术进展。详述了国外立式纺和卧式纺单丝技术。立式纺技术主要是纺牵一步法工艺和分丝技术的开发,卧式纺技术主要是指高强力单丝、多组分单丝、聚烯烃单丝丝束、非圆型截面单丝等特定的单丝专用生产线。指出国内高性能单丝供不应求,有待于进一步开发。     

聚甲醛纤维制备工艺及其性能的研究

以聚甲醛(POM)切片为原料,在200～210℃进行熔融纺丝制得POM长丝。利用DSC、Olympus偏光显微镜、单纱电子强力仪测定了POM纤维结晶度、熔点、取向度和纤维的机械性能;研究了后处理对POM纤维性能的影响以及拉伸对POM纤维耐酸碱性能的影响。结果表明:(1)POM纤维耐碱性良好,拉伸可以提高POM纤维结晶度、取向度、断裂强度以及耐酸性,但是使断裂伸长率减小;最佳拉伸温度在110℃左右,拉伸倍率在6～8之间。(2)热定形温度对POM纤维结晶度和熔点影响不大,延长热定形时间使POM结晶度、熔点降低;最佳热定形条件为在140℃下热定形4min。(3)经过拉伸热定形后的POM纤维的最大断裂强度和断裂伸长率分别为7.41cN/dtex和19.2%。     

珍珠粉改性聚丙烯单丝的制备及生物性能

为提高盆底修复补片用聚丙烯单丝的生物相容性,制备了聚丙烯/珍珠粉共混单丝。对纺丝工艺、珍珠粉在聚丙烯单丝表面的分散情况、改性单丝的力学性能及生物相容性进行了研究。结果显示,聚丙烯/珍珠粉共混单丝可纺性良好,珍珠粉的加入没有影响单丝的力学性能;SEM观察显示,珍珠粉在单丝表面大量分布;与不含珍珠粉聚丙烯单丝相比较,珍珠粉改性的聚丙烯单丝有更好的细胞增殖性能,说明珍珠粉填充的聚丙烯单丝作为补片原料植入人体时可望有更好的生物相容性。     

PPDO/PLLA皮芯复合单丝的体外降解

在磷酸盐(PBS)缓冲溶液中,对熔纺得到的两种聚对二氧环己酮(PPDO)/左旋聚乳酸(PLLA)皮芯复合单丝进行体外降解性能研究。结果表明:随着降解时间的延长,两种单丝的吸水率、质量损失率不断增加,相对黏度、强度保留率、断裂伸长率和缓冲溶液的p H值不断降低;随着降解时间的延长,两种单丝的熔融焓逐步升高;随着降解时间的延长,PPDO-PLLA单丝的表面形貌变化比PLLA-PPDO单丝的大,即PPDO的降解速率比PLLA更快。     

Tensile,Knot, and Detaching from Needle Performances of Atraumatic Surgical Sutures

In this study, atraumatic surgical sutures were used to investigate the effects of different structural parameters on tensile properties of unknotted and knotted (one, two, and three) sutures. Besides tensile properties, an important and crucial property namely detaching from needle property of the sutures were examined. Atraumatic surgical sutures having different lifetime in the body (nonabsorbable and absorbable), different raw materials (polypropylene [PP], silk, polydioxanone [PDS], polyglactin 910 [PGA]), different yarn structures (monofilament and braided), and different size numbers (2/0, 3/0, and 4/0 USP) were tested and variance analyses were used to examine the effects of structural parameters on test results. Tensile test results revealed that the presence of knot causes noticeable reduction in the breaking load values. However, the knotted sutures with varying throw number of knots were determined to have similar breaking properties. In addition, breaking load and detaching force from needle decrease with increasing size number of the sutures. In the case of the same size number and the same throw number of knot, absorbable sutures have higher breaking load results than non-absorbable sutures and braided sutures are stronger than monofilament sutures used in the study.     

国内化纤生产技术水平的提升空间与发展理念

扼要论述了国内化纤生产技术,诸如膨体连续长丝技术、涤纶工业丝技术、空气喷射技术、复合纺丝技术、纺丝成网技术、高性能单丝技术、短程纺丝技术、纤维素纤维的开发技术及产品结构等方面与国外的差距,阐明更新发展理念,正视差距,提升化纤生产技术水平的现实意义。     

新型热熔聚酯单丝的制备及性能

采用经改造的倍捻机及KF6-800弹力机将皮芯型复丝制成新型热熔聚酯单丝,初步探究不同工艺条件下生产的新型热熔聚酯单丝的特性。结果表明:在经改造后的倍捻机上制得的单丝的物理性能及外观截面都好于用KF6-800弹力机所制得的单丝,更适合于产业化的需求。     

A poly(L-lactic acid) monofilament with high mechanical properties for application in biodegradable biliary stents

In this article, a poly(L-lactic acid) (PLLA) monofilament with high mechanical properties which can be used to construct biodegradable biliary stents (BBS) is prepared. Compared with a commercial polydioxanone (PDO) suture, the PLLA monofilament has much higher Young's modulus. As a result, chronic outward force (COF) of the stent braided by PLLA monofilament is more than three times higher than that of the stent braided by PDO suture. Furthermore, by physicochemical indexes characterizations, it is acceptable that the PLLA monofilament has stable Young's modulus and higher elongation at break without brittle fracture risk during degradation in bile. In contrast, although PDO suture can also maintain Young's modulus well during degradation, its elongation at break is attenuated rapidly, which shows a high brittle fracture risk. These results indicate that PLLA monofilament is more suitable for constructing BBS with high COF, which are promising in treating more complex biliary strictures that need longer support time.     

The Use of Large Diameter Monofilament for Improving Peel Resistance of a Brittle High Temperature Adhesive

Peel force measurements as a function of adherend thickness are reported for adhesively bonded specimens based on a cyanate ester resin and aluminium adherends. It has been demonstrated that by incorporating large diameter (0.28mm) PTFE monofilament within the adhesive bond then the peel force and associated fracture energy can be increased significantly over that for specimens based on adhesive alone. Fracture energy measurements are derived for specimens with peeling adherend thickness of up to about 0.6 mm using the 90° peel test. Fracture energies are also derived for peeling of more practically-representative 1.6mm thickness adherends using a single cantilever beam experiment. In-situ photoelasticity and SEM microextensomctry experiments are reported which show the stress fields and displacements associated with the presence of the monofilament. It is believed that the reported increase in measured fracture energy is partly due to the crack pinning effect of the monofilament, and partly due to the monofilament creating a “load shadowed” region between adherend and monofilament which prevents the interfacial crack from propagating between adherend and adhesive.