坚持技术创新 攻克世界性技术难题

上海厚德橡塑材料有限公司研制成功超高摩尔质量聚乙烯（UHMWPE）注射与挤出成型技术。研究表明，UHMWPE摩尔质量越高，其熔融黏度越大，熔体质量流动速度与临界剪切速度越低，因而长期以来只能采用压制烧结法或用板材、棒材机械加工一些非连续形状制品，实际应用受到极大限制。上海厚德橡塑材料有限公司坚持技术创新，从机械、模具结构及加热方式等方面进行了一系列反复探索与试验，以多种结构优化组合创新设计了具有独特流动特性的流道与口模，终于攻克了UHMWPE“二低”给成型加工带来的许多技术难题，高质量实现了UHMWPE注射与挤出成型技术。     

不同成型方式下UHMWPE耐热改性进展

介绍了近年来超高分子量聚乙烯(UHMWPE)在模压成型、挤出成型、注塑成型方面的耐热改性研究进展,分析了采用不同成型方法对UHMWPE耐热改性的方法及改性效果。关于UHMWPE模压与挤出成型的耐热改性方法主要包括物理改性(填充改性、共混改性、共混填充改性)、化学改性(过氧化物交联、偶联剂交联、辐射交联)、聚合填充复合改性,而UHMWPE的注塑成型耐热改性研究较少。对UHMWPE进行耐热改性,加入的改性材料后,能显著提高复合材料耐热性,但是,部分材料的加入却降低了UHMWPE耐磨性、抗冲击性等性能,需要对UHMWPE注塑成型的耐热改性及改性材料的选用进一步研究。最后,对UHMWPE的耐热改性的发展趋势进行了展望。     

超高分子量聚乙烯(UHMWPE)的加工成型及共混改性

本文讨论了 UHMWPE 的几种加工成型方法,包括压制烧结成型、挤出成型、注射成型及吹塑成型等,并讨论了提高 UHMWPE 熔融流动性能的共混改性途径。     

超临界二氧化碳辅助PP/UHMWPE挤出成型的研究

研究了超临界二氧化碳对超高摩尔质量聚乙烯(UHMWPE)挤出成型的影响规律。首先将纯UHMWPE样条放到超临界二氧化碳中浸泡,研究对其力学性能的影响;然后在UHMWPE中加入一定量的聚丙烯(PP)进行共混,以改善UHMWPE的加工性能,并在通入超临界二氧化碳的条件下进行挤出成型。结果表明:超临界二氧化碳确能有效改善UHMWPE的加工性能,有利于UHMWPE成型加工;在超临界二氧化碳通入量一定条件下PP加入量对UHMWPE的加工性能和力学性能都有一定的提高。     

超高分子量聚乙烯成型加工及改性

介绍了近些年超高分子量聚乙烯（UHMWPE）的成型加工方法，由于UHMWPE熔体粘度极高，成型加工困难，通常采用模压成型，限制了其应用领域；通过综述中低分子量聚乙烯，聚丙烯，液晶聚合物及无机填料等改性UHMWPE所取得的成绩，指出解开UHMWPE的链缠结是改性最核心的问题。     

超高分子量聚乙烯成型加工技术最新进展

针对超高分子量聚乙(烯UHMWPE的)分子量大、熔体黏度高、临界剪切速率低和摩擦系数小而导致不易成型加工的问题重,点阐述了近几年UHMWPE的国内外成型加工技术最新进展包,括高速模压成型、固态挤出成型、气辅挤出成型及激光烧结成型等,并指出了提高黏均分子量1 000万以上的UHMWPE的加工效率是当今该领域的重要研究课题和发展方向。     

超高分子量聚乙烯管材机筒成型法

介绍了一种能够实现超高分子量聚乙烯(UHMWPE)管材连续挤出成型的新技术,即机筒成型法。该技术解决了纯UHMWPE管材难以成型的问题。     

超高分了量聚乙烯管材机筒成型法

介绍了一种能够实现超高分子量聚乙烯（UHMWPE）管材连续挤出成型的新技术,即机筒成型法。该技术解决了纯UHMWPE管材难以成型的问题。     

超高分子量聚乙烯滤芯双向压制烧结成型模具设计

针对超高分子量聚乙烯(UHMWPE)滤芯结构特点,设计了双向压制模具并介绍了该模具的结构特征及工作过程。根据UHMWPE粉末的成型特点,设计了模内加热系统。该模具既达到制备UHMWPE滤芯的要求,又符合微孔开孔成型的标准。     

超高分子量聚乙烯挤出设备批量投放市场

潍坊中云机器有限公司组织科技人员，经过几年的刻苦攻关，成功地研制生产出超高分子量聚乙烯（UHMWPE）挤出机组，实现了高效、高产、高质量、低成本连续不断的挤出管材、棒材、板材和异型材等，使超高分子量聚乙烯不易成型加工的世界难题得到了解决，投放市场后颇受用户的欢迎。该项目经山东省科技厅鉴定，达到目前国际领先水平，填补了国内空白。     

超高分子量聚乙烯管材内压法定型机理研究

"机筒成型法"是一种能实现纯UHMWPE管材单螺杆连续挤出成型的新技术,通过该方法所成型UHMWPE管材型胚,还需通过内压成型才能得到合格的产品。通过对UHMWPE管材内压定型温度场、内应力、应变产生机理进行分析,为内压定型装备的设计提供理论依据。     

The hierarchy structure and orientation of high density polyethylene obtained via dynamic packing injection molding

The evaluation of microstructure and crystal morphology in injected-molded bar becomes much complicated because of the existence of a shear gradient and a temperature gradient from the skin to the core of the samples. To understand the relationship between shear rate-molecular weight and oriented structure of injection molded bar, in this work, the hierarchy structure and the effect of molecular weight on the formation of shish-kebab structure were investigated by examining the lamellar structure of injection molded samples of high density polyethylene (HDPE) with different melt flow index (MFI), layer by layer, along the sample thickness. To enhance the shear effect, so-called dynamic packing injection molding (DPIM), in which the melt is firstly injected into the mold and then forced to move repeatedly in a chamber by two pistons that move reversibly with the same frequency as the solidification progressively occurs from the mold wall to the molding core part, was used to obtain the molded bar. Furthermore, a small amount of ultra-high molecular weight polyethylene (UHMWPE) was added into HDPE to explore the effect of UHMWPE on the crystal morphology and orientation. Our results indicated (1) that the overall orientation in the molded bar increased with decreased MFI, and a small amount of UHMWPE could enhance substantially HDPE orientation; (2) at the skin, there existed intertwined lamellae constituting an interlocked lamellar assembly, a typical shish-kebab structure gradually developed from the subskin-layer to the core, with increased shish content toward the center, but in the core was a spherulite-like superstructure with randomly distributed lamellae; (3) UHMWPE played an important role not only in the formation of shish, but also in the transformation from spherulite to shish-kebab oriented structure for HDPE with a low molecular weight (high MFI).     

Effect of sintering on processability vis-a-vis microcellular foaming of ultrahigh molecular weight polyethylene

Processing of ultrahigh molecular weight polyethylene (UHMWPE) involves sintering due to its high melt strength and no flowability above melting temperature. Variations in compression molding pressure during sintering lead to chain rearrangement at the sintered interphase and the boundary, affecting foamability. UHMWPE particles are sintered using compression molding; samples are prepared at two different pressures: UHPE-HP (80 bar) and UHPE-LP (40 bar) at 180°C. The sintering phenomenon of UHMWPE particles is observed through an optical microscope, and their effect on foaming was observed. UHPE-HP foams are systematically studied to obtain the foaming window. Increasing foaming pressure (80–120 bar) made UHPE-HP foams softer (0.350–0.219 g/cm³) with varying average cell size (26.37–46.1 μm) and foam cell density (3.98 × 10⁷–1.06 × 10⁸ cells/cm³), and compression modulus decreased from 9 to 5.4 MPa. DMA results showed a strong dependence of stiffness on crystallinity, and foamed samples exhibit higher stiffness than their unfoamed counterpart. The storage modulus for foamed samples decreases with increase in the gas content. The UHPE-LP foam is relatively softer, with a lower foam density (0.233 g/cm³), a higher expansion ratio, bigger average foam cells (35.13 μm), and lower foam cell density (9.33 × 10⁷ cells/cm³). This is due to constrained crystallinity at the interphase and pre-existing cavities, favoring the foaming.     

Experimental and simulated investigation of temperature distribution of UHMWPE laminated composites during hot pressing process

In this article, the influence of molding temperature on the mechanical properties and ballistic impact behavior of the ultrahigh molecular weight polyethylene (UHMWPE) laminated composites has been investigated. The results demonstrate that with the temperature increasing from 80 to 120 °C, the tensile strength decreases while the interlaminar bonding strength increases. The UHMWPE laminated composites manufactured by hot pressing of 75 layers UHMWPE fabrics show excellent ballistic performance when the molding temperature reaches 120 °C, indicating that dominant failure mechanism of the UHMWPE laminated composites are delamination, the fiber tension as well as bulging. Furthermore, a numerical model has been proposed to predict the temperature distribution of the UHMWPE laminated composites for a better understanding of the effect of molding temperature on the ballistic performance. The results show that the simulated results and experimental data are in good agreement. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45874.     

超高分子量聚乙烯的成型工艺及改性研究进展

本文介绍了超高分子量聚乙烯材料的基本性能,并由其性能决定的成型工艺,由于超高分子量聚乙烯熔体粘度极高,加工比较困难,限制了其的应用;通过综述近年来的超高分子量聚乙烯的改性研究进展,认为只有进行有力的改性研究,才可以将超高分子量聚乙烯的优异性能得到更为广泛研究和应用。     

超高相对分子质量聚乙烯的加工技术

介绍了模压烧结，挤出，注射，固态成型加工，射频加工，反应成型等UHMWPE（超高相对分子质量聚乙烯）的加工方法，并指出了各种方法的优缺点。     

Processing of ultrahigh molecular weight polyethylene

The extent of recrystallization of nascent UHMWPE powder is easily measured by calorimetry. Melting and recrystallization of nascent UHMWPE at 140°C can be suppressed by compression molding. Crystals of UHMWPE prepared from dilute solution show a peak melting temperature of 140°C and exhibit crystallinity up to 75.5% depending on crystallization temperature. Large changes in crystallinity result from drawing single crystal mats or compression-molded films.     

Fabrication of Polyimide-Modified UHMWPE Composites and Enhancement Effect on Tribological Properties

Polyimide-modified ultrahigh molecular weight polyethylene (UHMWPE) composites were fabricated by hot-press molding process. Mesoscopic morphologies of polyimide/UHMWPE blending systems show high compatibility between the phases of polyimide and UHMWPE when the weight ratio of polyimide is no more than 50?wt%. Investigation of the tribological properties with a reciprocating ball-on-flat contact tribometer shows that the polyimide filler has important effects on the friction and wear behavior of UHMWPE composites. Compared to pure UHMWPE, the composite with 50?wt% polyimide improved tribological properties best and exhibited 43.1% reduction in friction coefficient and 66.7% reduction in wear volume loss.