医用复合变径管挤出工艺及主动脉插管的开发

很多医用导管制品是用管壁笔合不透Ｘ射线材料,管径粗细有明显变化的民径管材（又称“气泡管”）再加工的,本文介绍了制造这种管材的新型挤出成型工艺以及相关设备的要求,同时还介绍了采用这种工艺开发的体外循环用主动脉插管的应用情况。     

精密医用塑料导管机遇与挑战并存

精密医用导管的主要特征是：尺寸微小、形状复杂、几何精度要求高、卫生指标高、生化稳定性高等。导管的主要部件是管材部分,要求管材内外表面光滑平整、尺寸精密且稳定。导管的直径一般为0.5 mm至数毫米,允许的直径偏差一般为5%以下。而采用普通塑料管材生产设备生产的塑料管材,其直径偏差高达20%~30%,无法满足精密医用导管的生产要求。精密医用导管的管材部分采用挤出成型方法生产,配件主要采用注射成型方法生产。其中管材部分的生产工艺流程如下：根据导管的几何尺寸和材料,设定合理的工艺参数,包括原料配方、原料干燥条件、挤出温度、螺杆转速、冷却介质的温度和流量等。     

保持医用管材的形状和尺寸

随着新型医用多腔管结构的日趋复杂，对挤出成型工艺也提出了越来越高的要求。利用电力调压控制系统可快捷、准确地控制内径空气和冷却槽压力，使管材在成型过程中能够保持严格的形状和尺寸。[编者按]     

新型烟草用聚乳酸降温段挤塑加工

对聚乳酸(PLA)降温段异型管产品结构、挤出模头设计及挤塑成型原理进行研究,进而对PLA降温段异型管挤塑成型工艺进行系统分析.提出了影响PLA降温异型管挤塑加工成型生产效率的关键工艺参数,如挤出模具、定型定径套管长度、真空度等,为得到稳定挤出的PLA降温段产品提供系统思路.     

充气橡胶软芯在橡胶异型管生产中的应用

我国橡胶异型管的生产方式大体上可分为挤出成型硬芯硫化法和模具直接成型硫化法两类。其中 ,前者在挤出成型时又可分为硬芯成型法、橡胶软芯成型法和无芯成型法 3种。这 3种方法各有其特点 ,硬芯成型法的制品内径尺寸控制精确 ,半成品易脱芯 ,不受骨架层结构限制 ,现被大部分生产厂家采用 ,其缺点是异型管的半成品长度小、截头多 ,且在生产过程中使用大量的硅油作脱芯润滑剂 ;橡胶软芯成型法的异型管半成品脱芯困难 ,且软芯本身的生产制造存在很多问题 (如尺寸形状很难控制 ) ,因此在异型管的生产中很少使用 ;无芯成型法是技术雄厚、设备先…     

高强度聚烯烃管材成型方法的研究进展

介绍了7种高性能聚烯烃管材成型技术的原理及优缺点,这些成型方法主要通过改变加工过程中的温度场及应力场等来提高管材的环向强度。其中,三层复合管材旋转挤出成型技术是一种简单而有效生产高性能复合管材的成型技术,是未来生产高性能复合增强管材的一种趋势,该技术具有十分广阔的应用前景。     

挤出胀大逆向求解技术在多腔精密医用导管口模设计中的应用

口模截面形状的设计是多腔精密医用导管挤出成型中的一个难点,采用Polyflow软件逆向求解挤出胀大过程的功能,分析双孔异径和双腔异型两类典型多腔精密医用导管的逆向求解过程,给出了生产理想制品所需的口模截面形状.同时针对多腔精密医用导管在成型过程中内腔存在微量气压这一特征,逆向求解了在微量气压作用下的口模截面形状,为实际设计过程中机头口模的确定和修改提供了依据.此外,也对其它4类典型的多腔精密医用导管进行了逆向分析,给出了无气压作用下的口模截面形状.对于多腔精密医用导管机头口模设计具有较高的参考价值.     

基于超声波测量技术聚合物精密挤出成型制品质量精度的控制方法

根据超声波在传播介质中快速响应的特性,介绍基于超声波的聚合物管材壁厚及外径测量技术,在分析影响精密挤出制品质量因素的基础上,提出将超声波测距技术应用于精密医用导管挤出成型过程中,实现管材壁厚及外径的在线测量。通过挤出管材米重Gm(单位长度质量)-牵引机速度的闭环反馈控制,完成管材壁厚及圆度的在线精确控制,达到精密挤出导管几何截面尺寸高精度的要求。     

改进工艺制备PVC-O管材料特性试验分析

分析了硬聚氯乙烯(PVC-U)管材自身的优劣势,引出基于双轴取向拉伸工艺的技术改进方法。通过对双轴取向聚氯乙烯管(PVC-O)现状分析,提出PVC-O管量产化的改进工艺成型方法,并完成了PVC-O管的制备。对成品管与未改进的PVC-U管进行了三组对比关联试验,通过环刚度、环柔度试验,观察两种PVC制品的裂纹微观结构,得到两种管材的制品指标和特性,三组试验均证实了PVC-O管优于传统PVC-U管材,且改进工艺提升了PVC管材产品的质量,这为PVC-O管生产与应用提供科学依据。     

专利技术

一种PVC暖气罩及其加工工艺、渐变型塑料光纤多层复合挤出成型工艺、剖分式双螺杆挤出机、“L”型单辊筒机头、充气连接制造缠绕钢丝增强复合塑料管材的装置     

PVC超强筋管的生产及应用

ＰＶＣ超强筋是以传统的挤出工艺运用新生产技术上设备制造出来具有独特设计的管道。其带有系列径向加强筋，大大提高了抗冲击强度、并且比同直径光壁管节约用料４５％。     

异形医用双腔导管挤出离模膨胀变形机理与调控

如何准确预测和精密调控异形医用双腔导管的离模膨胀变形是实现其精密成型的关键技术。通过传统和气辅精密成型的对比分析，研究表明离模膨胀变形是由熔体的第二法向应力差驱动的径向二次流动所诱发，传统挤出成型会产生较大的第二法向应力差，第二法向应力差驱动诱发的径向二次流动是离模膨胀变形的直接驱动力，从而导致传统挤出成型的异形医用双腔导管不仅产生离模膨胀，而且还产生椭圆度误差，其最大离模膨胀比和椭圆度误差分别为1.86和6.3 %。异形医用双腔导管的气辅精密挤出成型基本可以消除熔体的第二法向应力差，必然消除了挤出成型过程的径向二次流动，从而实现了异形医用双腔导管的精密控形。     

工艺条件对玻纤增强ABS性能的影响

研究了加工工艺对玻璃纤维增强ABS性能的影响。结果表明，适宜的加工工艺和加工条件能够将ABS和玻璃纤维本身的优良性能充分表现出来，挤出温度、挤出速度及注射速率都是影响材料性能的重要因素。在玻纤维增强ABS加工过程中，采用侧向加料、提高ABS的加工温度、降低挤出压力和注射速率等措施，可提高材料的力学性能。     

螺杆挤出式3D打印机结构设计与仿真分析

分析了传统桌面级FDM型3D打印机与螺杆挤出式3D打印机的挤出原理,为提升桌面级FDM型3D打印机对打印材料的兼容性并降低打印材料的制作成本,设计了螺杆挤出式3D打印机新结构,具有螺杆与机筒便捷拆换功能.结合设计计算获得了适用于打印丙烯腈?丁二烯?苯乙烯共聚物(ABS)材料的螺杆计量段结构,在螺杆低转速与小型化的要求下...     

Theoretical and experimental study on three-layered polymeric balloon catheter processing

Multilayered polymeric balloon catheters, one of the most important components during interventional treatment, are drawing more attention recently due to the microscale cross section, excellent mechanical properties, and high accuracy. During multilayered polymeric balloon catheter processing, many operating conditions can affect the size and shape of cross sections. In this study, polymer melt flow behavior inside extrusion die is theoretically analyzed first. Then, ethylene vinyl acetate (EVA) and polypropylene (PP) are selected as the build materials to produce the middle and inner layers of three-layered polymeric balloon catheters, while polyamide (PA) and thermoplastic elastomer (TPE) are used to make the outer layer of two types of catheters, respectively. Based on the material selection, a three-layered coaxial die is designed and manufactured to coextrude three different polymer melts to form corresponding catheters. In addition, the effects of operating conditions including outer layer materials, pulling speed, gas flow rate, and screw rotation speeds on the diameters and wall thicknesses as well as the concentricity and ovality of the extrudates are investigated. Finally, the PA-EVA-PP and TPE-EVA-PP three-layered catheters are successfully fabricated, which have well-defined geometries and high shape accuracy.     

Effects of extrusion process,type and content of clays,and foaming process on the clay exfoliation in HMS PP composites

The use of a high melt strength polypropylene (HMS PP) matrix reinforced with layered clays could be very useful to improve the properties of materials produced with processes involving melt stretching, like foaming. The control of the particles structure, that is, the degree of exfoliation and the clay distribution in the polymeric matrix, is the key to achieve the desired properties. In this study, the effects of the extrusion process, the clay type and content, and the foaming process on the morphology of different HMS PP based composites are studied. Both, natural and organomodified clays were used. The extrusion process has a negative effect in the composites containing natural clays as their interlayer distance decreases as the number of extrusion cycles increases. On the contrary, this process improves the intercalation of the organomodified clays. However, in both composites the interlayer spacing decreases when the clay content increases. While a percolated network is formed in the composites containing organomodified clays, no network is formed with the natural clays. Finally, the effect of the foaming process has also been analyzed. The Improved Compression Moulding (ICM) route was used to produce the foamed materials. This technique subjects the materials only to a temperature and a pressure gradient without applying any other external forces that could contribute to the clay exfoliation. In this way, only the effects of foaming and melt stretching are observed. In both composites, an increase in the interlayer distance is observed when the materials are foamed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42828.     

超高分子量聚乙烯气辅挤出影响因素的数值模拟及分析

以超高分子量聚乙烯的圆形轴对称气辅口模挤出为研究对象,在采用Polyflow软件对气辅口模挤出时的等温流动进行数值模拟之后,就入口流率、松弛时间以及零剪切黏度等物性和工艺参数对挤出胀大、速度分布、口模压降和熔体外表面上剪切速率的影响进行了数值模拟和分析。分析表明:气辅挤出是克服超高分子量聚乙烯传统挤出时面临一系列困难的有效加工方式。     

反应挤出合成聚乳酸与脱挥技术研究

主要介绍了反应挤出合成聚乳酸的技术特点和脱挥技术应用;分析了反应挤出合成过程中脱挥处理的关键点和影响因素。相比传统的聚乳酸合成技术,因其具有突出的优势,预计是今后聚乳酸合成发展的研究热点。     

Measurement of some rheological properties of plastic fats with an extrusion modification of the shear press

An extrusion attachment for the Lee-Kramer shear press is described. With this instrument some rheological properties of lard, margarine and shortening were measured. These included extrusion pressure and specific work of extrusion. By variation of extrusion speed and size of orifice a variety of rates of deformation could be obtained. When the rate of deformation was plotted against the specific work of extrusion, curves were obtained which were nearly straight beyond deformation rates of about 1 sec^-1. The tangent to these curves represents the apparent viscosity. By measurement of the hardness before and after extrusion the work softening resulting from the extrusion could be measured. Some possible uses of the technique are discussed.