注塑工艺对PVC-U合金性能的影响

研究了注塑工艺对PVC-U合金性能的影响,结果表明:在注射温度185℃、注射压力80MPa、注射速度60g/s、注射时间5s的工艺条件下,注塑制品具有较好的力学性能。     

注塑工艺及调湿处理对半芳香透明尼龙力学性能的影响

研究了模具温度、注塑压力和注射速率对半芳香(SA)透明尼龙拉伸强度、断裂伸长率、弯曲强度、弯曲弹性模量和缺口冲击强度等力学性能的影响,并对SA透明尼龙调湿处理前后的力学性能进行了比较。结果表明,当料筒温度为240～245℃,注塑压力为70-130MPa,模具温度为40—80℃时,SA透明尼龙能顺利注塑,其力学性能随注塑压力的增大呈提高趋势,而模具温度和注射速率对其力学性能影响不太明显;经过调湿处理后,SA透明尼龙的缺口冲击强度有所提高。     

微孔发泡注塑注气量控制的理论和实验

微孔发泡注塑是1种新型成型工艺,能够在基本保持制品原有力学性能的前提下明显减轻制品质量。在注塑过程中,注气量的多少对制品特性有很大影响。通过对微孔发泡注塑系统注气量的实验和模拟,利用现代控制理论及数据分析方法,建立注气系统的数学模型,得到一定工艺条件下注气量与注气压力及熔体压力之间的关系。     

注塑工艺对通用膜料DFDA-7042产品力学性能的影响

采用注塑成型方法制备了通用膜料DFDA-7042试样,研究了注塑条件对试样力学性能的影响,并对加工条件进行了优选。结果表明,适宜的注射压力在3~5 MPa之间,保压压力在3~4.5 MPa之间,保压时间设定在20 s,冷却时间设定在30~45 s之间,注射速率设定在100~120 mm/s。     

长玻纤增强聚丙烯复合材料注塑成型工艺优化

通过熔融浸渍包覆工艺,制备玻纤含量为40%的长玻纤增强聚丙烯复合材料(LGFRPP)粒料,选择注塑温度、注射压力以及注射速率作为试验的3个因子,将拉伸强度、弯曲强度及冲击强度作为评价指标,利用正交实验设计的方法对LGFRPP的注塑成型工艺进行了优化研究,研究了各注塑工艺对力学性能的影响,得到最佳注塑成型条件。研究结果表明,对拉伸性能影响最显著的是注射速率,对弯曲性能影响最显著的是注塑温度,对冲击强度影响最显著的是注射压力;采用综合平衡原则,结合拉伸、弯曲和冲击性能,得到含量为40%的LGFRPP复合材料的最佳注塑成型条件为注塑温度250℃,注射压力40 MPa,注射速度60%。在最佳工艺条件下,材料的拉伸强度为132. 02 MPa,弯曲强度为200. 38 MPa,冲击强度为59. 34 k J/m2。     

聚保物熔体流变性能在气辅注塑工艺的影响

应用Ｈｅｌｅ－Ｓｈａｗ物理模型和改进的Ｃｒｏｓｓ流变模型及有限元算法对５种聚丙烯的气辅注塑过程进行了模拟，研究了不同聚丙烯材料在充填速度相同的条件下的压力及锁模力变化规律。结果表明，气辅注塑在气体注射后与传统注塑有较大差异，所需压力，锁模力均比传统注塑有显著降低，且聚合物的熔体流动速率减小，气体注射后产生的压力降越大，表明在生产中应尽可能选用高熔体流动速率树脂以利于气辅注塑工艺。     

注塑工艺对ASA光泽的影响

采用双螺杆挤出机加入消光剂等助剂制备了不同光泽的高耐候丙烯腈–苯乙烯–丙烯酸酯塑料(ASA),并研究了注塑温度、注射速度、模具温度、保压压力以及保压时间等注塑工艺对ASA注塑制品表面光泽的影响。结果表明,消光剂在ASA中有很好的哑光效果,通过控制其添加量可以获得力学性能和低光泽综合性能优异的哑光ASA。注塑工艺对ASA光泽研究结果显示,模具温度和注塑温度是影响ASA表面光泽的最主要工艺参数。在合理的注塑加工范围内,适当地提高注塑温度、模具温度和保压压力,以及适当地延长保压时间可以获得低光泽效果优异的注塑件。     

注塑工艺对聚丙烯EP548N光学性能的影响

采用不同的工艺条件对无规共聚聚丙烯EP548N进行注塑成型,测试注塑件表面光泽度、黄色指数和透光率,分析了注塑成型条件对制品光学性能的影响。确定聚丙烯EP548N的最佳注塑工艺为:熔体温度200℃,模具温度40℃,注射速度210mm/s、保压压力4.6MPa、注射压力4.9MPa,注塑工艺条件改变对聚丙烯EP548N注塑件透光率影响较小。     

仿真研究聚丙烯流变性能对气辅注塑的影响

应用计算机仿真手段研究了不同聚丙烯在充模速度相同条件下的压力及锁模力变化规律。结果表明，气辅注癃民传统注塑相比，所需压力，锁模力均有显著降低，且聚合物熔体流动速率越小，气体注射后产生的压力降赵大，表明在生产中应尽可能选用高ＭＦＲ树脂以利于气辅注塑工艺。     

碳纤维/聚丙烯复合材料的注塑成型及性能研究

通过注塑成型制备了不同碳纤维质量分数的碳纤维/聚丙烯复合材料,研究了复合材料的流动性、注塑工艺条件、力学性能和电学性能。结果表明,含有碳纤维复合材料的流动性下降,在注塑时须相应提高注射温度;在一定含量范围内,含碳纤维量复合材料的拉伸强度提高;含碳纤维量复合材料的电阻率明显下降。     

Self-Reinforced Isotactic Polypropylene Prepared by Melt Vibration Injection Molding

Polypropylene (PP) has a good combination of properties, but at low temperatures it is friable and its impact ductility is very low. To improve impact strength, a vibration injection molding (VIM) technology was used to investigate the mechanical properties of polypropylene. Yield strength is upgraded with an increment in vibration frequency and a peak stands at a special frequency for VIM; the elongation at break and impact strength are also enhanced by increased vibration frequency. The wide-angle x-ray diffraction (WAXD) curves and the scanning electronic microscopy (SEM) micrographs have shown that, in the vibration field, the enhancement of mechanical properties is attributed to the occurrence of γ-phase crystals and more pronounced spherulite deformation than those seen in conventional injection moldings (CIM), and the smaller spherulites with the existence of β-phase crystals are favored for improving toughness. With the application of vibration injection molding, the mechanical properties of isotactic PP are improved. To prepare self-reinforcing and self-toughening polypropylene molded parts it has been concluded that high vibration frequency is required. Increasing vibration pressure amplitude obviously significantly improves the yield strength and impact strength.     

Self‐interference flow of an isotactic polypropylene melt in a cavity during injection molding. I. Effect of the self‐interference flow on the properties

The self‐interference flow (SIF) of a melt in a cavity during injection molding is introduced. It comes from two streams of the melt being split by a patented mold gate called a twin gate. The effects of this flow on the static and dynamic mechanical properties, thickness distribution, and shrinkage in the transverse direction (TD) of injection‐molded isotactic polypropylene parts are discussed. SIF has an influence on the static mechanical properties, especially the impact strength. There are slight increases in the tensile strength and Young's modulus and an increase of approximately 70–90% in the impact strength in comparison with the properties of samples obtained by a conventional flow process with a common pin gate. Dynamic mechanical thermal analysis studies show an increase in the storage modulus for SIF samples. Results obtained from research into the effect of the mold temperature and injection pressure on the impact strength show that the impact strength of SIF specimens has a weaker dependence on the mold temperature and injection pressure. In addition, the flow brings a more uniform thickness distribution and a smaller shrinkage in the TD to SIF samples. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2784–2790, 2003     

PET的注射成型工艺对制品性能的影响

通过注射成型试验探索聚对苯二甲酸乙二酯(PET)的成型工艺条件,并结合紫外可见光谱和力学性能测试方法,分析注塑成型工艺对PET性能的影响。研究发现:PET适宜的注射成型温度为280℃,模具温度为70℃,注塑压力为50 MPa,冷却时间为20 s。此条件下制得的PET制品不易结晶、透明无缺陷、无翘曲和凹痕、综合力学性能较好,拉伸强度、弯曲强度及弯曲弹性模量较小,断裂伸长率和缺口冲击强度较大。     

注塑模具设计过程中浇口尺寸对塑料制品力学性能的影响

以高密度聚乙烯（PE-HD）为原料，采用自行设计加工的一套1模4腔注射标准试样模具进行注塑，通过调整熔体温度、模具温度和注射压力等工艺参数，考察了不同浇口截面尺寸的模具对注塑样品拉伸、冲击和弯曲性能的影响。结果表明，模具浇口截面尺寸修改后，注射试样的力学性能明显提升，其中，拉伸强度、冲击强度、弯曲强度和弯曲模量最高分别提升了3.40 %、79.86 %、18.11 %和113.36 %；模具浇口修改后注塑所的样品充填饱满，无塌陷等缺陷；修改浇口后的模具设计整体结构布局合理，可为同类标准测试样的成型模具设计提供有益借鉴。     

The relationship between mechanical properties and morphology of vibration‐injection‐molded polyethylene

This paper introduces a novel melt vibration‐injection molding. The effect of mid‐frequency melt vibration on mechanical properties was introduced, and SEM, WAXD and DSC investigations had been employed to provide evidence for explaining the relationship between mechanical properties and morphology of vibration‐injection‐molded specimens. The results show that the effect of vibration frequency is very different from that of vibration pressure amplitude. At a given vibration pressure amplitude, the increase of vibration frequency is beneficial for obtaining preferential orientation, more perfect lamellae and enhanced mechanical properties. For a given vibration frequency, increase of vibration pressure amplitude is a pre‐requisite for the achievement of a large‐scale lamella, more pronounced orientation, increase of cyrstallinity and high strength of high‐density polyethylene, but part of the toughness is lost. Copyright © 2004 Society of Chemical Industry     

电磁动态注塑对等规聚丙烯增韧和增强研究

利用普通注射成型和电磁动态注塑机注射成型制备等规聚丙烯试样，并对其进行拉伸强度、冲击强度、差示扫描量热仪（DSC）和广角X射线衍射（WAXD）测试。对动态与稳态注射成型聚丙烯制品的力学性能进行了比较，并结合微观测试结果，深入探讨了制品微观结构与力学性能之间的关系。力学测试结果表明，动态成型制品的拉伸性能和冲击性能比稳态加工条件下都有所提高，尤其是制品冲击性能的提高幅度可以达到40％以上，实现了对制品的同时增强和增韧。DSC和WAXD测试表明，动态成型制品的结晶比稳态制品完善，并且晶粒尺寸也小于稳态制品。经过理论分析，认为结晶情况的改善是制品拉伸强度提高的原因，而晶粒细化则大幅度提高了制品的冲击强度。     

振动注射成型技术研究

对本课题组多年来进行的动态保压注射成型、剪切振动注射成型和压力振动注射成型研究进行了简要总结。振动注射成型不仅能改善聚合物熔体的高黏度、难流动、压力传递难等工艺问题,还能部分挖掘出聚合物材料的力学潜能,达到自增强,具有重要的理论意义和实用价值。     

Effect of packing pressure on fiber orientation in injection molding of fiber‐reinforced thermoplastics

Injection molding of fiber‐reinforced polymeric composites is increasing with demands of geometrically complex products possessing superior mechanical properties of high specific strength, high specific stiffness, and high impact resistance. Complex state of fiber orientation exists in injection molding of short fiber reinforced polymers. The orientation of fibers vary significantly across the thickness of injection‐molded part and can become a key feature of the finished product. Improving the mechanical properties of molded parts by managing the orientation of fibers during the process of injection molding is the basic motivation of this study. As a first step in this direction, the present results reveal the importance of packing pressure in orienting the fibers. In this study, the effects of pressure distribution and viscosity of a compressible polymeric composite melt on the state of fiber orientation after complete filling of a cavity is considered experimentally and compared with the simulation results of Moldflow analysis. POLYM. COMPOS. 28:214–223, 2007. © 2007 Society of Plastics Engineers     

注塑成型熔接线截面熔接过程数值模拟

在多浇口和带嵌件注塑制品的成型过程中必然存在熔体的熔接过程,从而形成熔接线。熔接线沿厚度方向的熔接过程是影响该区域的力学强度以及纤维取向等制品性能的重要因素。本文采用有限元法针对注塑制品的典型截面建立数学模型,采用T6P3单元(速度二次插值,压力线性插值),数值模拟了注塑制品熔接线的截面熔接过程。通过等厚度截面和非等厚度截面两个算例,给出了两股熔体熔接过程中的截面速度场和压力场分布。讨论了熔接线区域的壁厚均匀程度对熔接过程的影响。该计算结果可以为制品力学性能以及纤维取向等数值模拟提供数据支持。     

Influence of processing condition and carbon nanotube on mechanical properties of injection molded multi‐walled carbon nanotube/poly(methyl methacrylate) nanocomposites

In this work, multi‐walled carbon nanotubes (MWCNT) and poly(methyl methacrylate) (PMMA) pellets were compounded via corotating twin‐screw extruder. The produced MWCNT/PMMA nanocomposite pellets were injection molded. The effect of MWCNT concentration, injection melt temperature and holding pressure on mechanical properties of the nanocomposites were investigated. To examine the mechanical properties of the MWCNT/PMMA nanocomposites, tensile test, charpy impact test, and Rockwell hardness are considered as the outputs. Design of experiments (DoE) is done by full factorial method. The morphology of the nanocomposites was performed using scanning electron microscopy (SEM). The results revealed when MWCNT concentration are increased from 0 to 1.5 wt %, tensile strength and elongation at break were reduced about 30 and 40%, respectively, but a slight increase in hardness was observed. In addition, highest impact strength belongs to the nanocomposite with 1 wt % MWCNT. This study also shows that processing condition significantly influence on mechanical behavior of the injection molded nanocomposite. In maximum holding pressure (100 bar), the nanocomposites show highest tensile strength, elongation, impact strength and hardness. According to findings, melt temperature has a trifle effect on elongation, but it has a remarkable influence on tensile strength. In the case of impact strength, higher melt temperature is favorable. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43738.