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介绍多组分注射成型工艺技术等混合注射技术,目前已被越来越多的塑料制品生产厂家采用,可生产出多种符合时代要求的塑料制品,如汽车零部件以及电子通汛产品部件等。混合注射成型技术将成为最重要的塑料制品加工工艺之一。 相似文献
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长纤维增强热塑性塑料力学性能比普通短纤维增强塑料有很大的提高,注射成型中保持纤维的长度是关键。本文对长纤维增强热塑性塑料(LFT)注射工艺进行了简要绍,并对影响纤维长度的设备及工艺方面的因素进行了总结。 相似文献
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Summary: An in‐line method for monitoring the solidification process during injection molding of semicrystalline polymers (demonstrated previously in J. Appl. Polym. Sci. 2003 , 89, 3713) is based on a simple device, where an additional ejector pin is pushed on the injection molded part at different times during the solidification phase. The ‘indentation depth profile’, i.e., residual deformation as a function of time, was obtained and allowed to determine the evolution of the solidification front in the mold as a function of the cooling time. The present work shows the reliability and the powerfulness of the aforementioned method for a large variety of different semicrystalline polymers (PET, PBT, polyamide‐6 PA6, isotactic poly(propylene) iPP) characterized also by different molecular weight and/or nucleating agents. The results show that the indentation test may be considered as a ‘predictive’ tool to qualitatively and quantitatively compare the solidification process of different polymers and polymer grades during injection molding.
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Alex Hamilton Jack Perris Neil Convery Daniel M. Mulvihill Nikolaj Gadegaard 《大分子材料与工程》2021,306(9):2100223
Mass production of microfluidic devices commonly relies on injection molding. Injection molding requires a master surface made using micro or nanofabrication. Conventionally, electroplating from a silicon master is used for mold insert production, but this is expensive and cannot be used with masters produced via the Bosch process as interlocking of the scalloping between polymer and metal insert hinders part ejection. Here, an alternative to the electroplating process is developed by adapting a nanoimprint route to produce flexible micro-structured polymer inserts capable of molding using a Bosch process-produced master. An optimized fabrication approach using silicon masters with smooth sidewalls (produced using the mixed process) is used to characterize the limits of the process. Aspect ratios of 1 and below are successfully replicated. Feature spacings down to 20 µm are successfully produced with minimal variation between repeated parts. Masters produced using two different Bosch etches exhibiting both coarse and fine nanometer scalloping are also studied. Parts are successfully ejected with retained nanometer scalloping in all samples although inlay damage occurred after >10 replicas. A proof-of-concept microfluidic device is successfully produced vindicating the use of this approach as an efficient and cost-effective approach for the rapid prototyping of complex micro-structured designs. 相似文献
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综述了微注射成型技术存在的问题和改进方法,探讨了微注射成型机的塑化、注射和计量等装置的结构性能改进,并提出了监测系统的改进方案。在比较微注射成型模具和常规注射成型模具基础上,介绍了微注射成型模具的特殊变模温控制方法、抽真空排气方法、模具材料选择及模芯微细加工方法。还探讨了特殊热塑性塑料材料的开发和微注射成型零件的检测和处理方法,并进一步分析了微流动特征下计算机模流分析软件适应性。 相似文献
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The nanometer scale topography of self‐assembling structural protein complexes in animals is believed to induce favorable cell responses. An important example of such nanostructured biological complexes is fibrillar collagen that possesses a cross‐striation structure with a periodicity of 69 nm and a peak‐to‐valley distance of 4–6 nm. Bovine collagen type I was assembled into fibrillar structures in vitro and sedimented onto solid supports. Their structural motif was transferred into a nickel replica by physical vapor deposition of a small‐grained metal layer followed by galvanic plating. The resulting inverted nickel structure was found to faithfully present most of the micrometer and nanometer scale topography of the biological original. This nickel replica was used as a die for the injection molding of a range of different thermoplastic polymers. Total injection molding cycle times were in the range of 30–45 seconds. One of the polymer materials investigated, polyethylene, displayed poor replication of the biological nanotopographical motif. However, the majority of the polymers showed very high replication fidelity as witnessed by their ability to replicate the cross‐striation features of less than 5 nm height difference. The latter group of materials includes poly(propylene), poly(methyl methacrylate), poly(L ‐lactic acid), polycaprolactone, and a copolymer of cyclic and linear olefins (COC). This work suggests that the current limiting factor for the injection molding of nanometer scale topography in thermoplastic polymers lies with the grain size of the initial metal coating of the mold rather than the polymers themselves.
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注射成型工艺对PBT结晶和降解行为的影响 总被引:2,自引:0,他引:2
通过采用不同的注射条件,分别考察了熔体温度、模具温度、螺杆转速、注射速率、背压、保压压力、保压时间、滞留时间等多个重要的注射参数对聚对苯二甲酸丁二醇酯(PBT)小型制件降解程度、结晶形态和力学性能的影响。利用偏光显微镜、DSC、黏度计等,着重研究了各注射工艺参数对制件皮层厚度、结晶度、相对分子质量以及断裂伸长率的影响,从而为优化注射成型工艺过程提供依据。结果表明:熔体温度对制件各项性能的影响最为显著,而螺杆转速、背压、保压压力等的影响相对较小;随着熔体温度的提高和滞留时间的延长,PBT的降解程度迅速加剧,相对分子质量急剧下降,从而使制件断裂伸长率严重降低,力学性能变差。 相似文献
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In this study, we investigated the feasibility of injection molding (IM) and injection compression molding (ICM) for fabricating 3.5‐in. light‐guided plates (LGPs). The LGP was 0.4 mm thick with v‐grooved microfeatures (10 μm wide and 5 μm deep). A mold was designed to fabricate LGPs by IM and ICM. Micromachining was used to make the mold insert. The Taguchi method and parametric analysis were applied to examine the effects of the process parameters on the molding quality. The following parameters were considered: barrel temperature, mold temperature, packing pressure, and packing time. Mold temperature in this investigation was in the conventional range. Increasing the barrel temperature and mold temperature generally improved the polymer melt fill in the cavities with microdimensions. The experimental results for the replication of microfeatures by IM and ICM are presented and compared. The height of the v‐grooved microfeatures replicated by ICM was more accurate than those replicated by IM. Additionally, the flatness of the fabricated LGPs showed that ICM was better than IM for thin‐walled molding. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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研究了聚合物电磁动态注射成型过程中熔体在轴向振动力场作用下在圆柱形流道中的流动情况。从理论上分析了动态熔体流动过程,为研究聚合物熔体的动态充模过程提供流道系统压力降。得出在施加了轴向振动的情况下,熔体的压力梯度有明显的降低,并且随着振动强度的增强,降低的幅度加大。 相似文献
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对长玻纤增强聚丙烯(LFT-PP)和短玻纤增强聚酰胺(SFT-PA6)的性能进行了测试与比较。常温时(23 ℃),悬臂梁缺口冲击强度前者比后者提高3.44 %,吸水率后者比前者高100 %,模收缩率前者比后者低10 %;低温时(-30 ℃),前者的冲击强度提高了16 %~24 %。通过优化的模具设计、模流数值计算分析和注塑工艺条件实验,选择最佳注塑工艺参数制备LFT-PP叶片,可使叶片疲劳断裂强度的最大静载荷测试值达到150 kg。 相似文献
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介绍了一种耐高温的注射型酚醛模塑料的配方、工艺及特性。采用复合固化体系,以酚醛树脂为基体树脂,以无机纤维为增强剂,制备了耐高温的注射型酚醛模塑料。该材料不但具有较好的适应注射成型需要的流动性和流变特性,而且成型后具有较高的热变形温度(264℃)和热稳定性(300℃)。 相似文献
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我国注塑机的特点及发展方向 总被引:11,自引:0,他引:11
简略分析了我国注塑机的发展现状与技术水平,指出了我国注塑机在总体技术水平、机械机构和结构、控制系统等诸方面与国外先进水平的差距,提出了今后的研制重点和发展方向,可供专业人士参考。 相似文献
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塑料粘接磁体注射成型技术的研究 总被引:1,自引:0,他引:1
阐述了塑料粘接磁体注射成型工艺、特点,着重分析了粘接剂、磁粉含量、磁场注塑机、模具结构等关键技术对塑料粘接磁体生产与使用的影响. 相似文献