共查询到20条相似文献，搜索用时 15 毫秒
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Vijay K. Stokes 《Polymer Engineering and Science》2020,60(12):2963-2966
The perspective in this note explores rationally defined scaling parameters for injection molding to account for the length and thickness of parts, the melt temperature, the injection pressure, and the injection speed: Injection-molding parameters, first empirically established for 4- to 5-mm-thick parts, were later experimentally optimized for 2- to 3-mm thick parts. The push for even thinner parts required major adjustments in molding technology, including the use of lower-viscosity materials. This shift from thicker to thinner parts was arbitrarily characterized by the length-to-thickness ratio of the part, which is shown to be incorrect. 相似文献
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Feng Luo Chenlong Xu Nanying Ning Ke Wang Hua Deng Feng Chen Qiang Fu 《Polymer International》2013,62(2):172-178
The phase morphology and toughening behavior of impact polypropylene copolymer (IPC) with and without nucleating agent (NA), prepared at different processing melt temperatures (Tp), were investigated. Interestingly, three different structures can be formed in the IPC samples by adding NA or tuning Tp. A well‐defined core–shell structure is obtained in samples with α‐NA or without NA prepared at all Tp. A developing multilayered structure is mainly formed at high Tp with added β‐NA, while an incomplete phase separation structure with interpenetrating chains is the dominant structure for IPC samples prepared at low Tp with added β‐NA. In this case, because of the synergistic effect between phase morphology and relatively high β‐form crystal content, the chain interaction among the components and chain mobility of the amorphous portion of IPC are distinctly improved, resulting in a largely improved toughness under 0 °C. This improvement in toughness is very important for applications. © 2012 Society of Chemical Industry 相似文献
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通过一次因子法确定了Taguchi法的试验因子,采用Taguchi法对试验因子进行权重分析与优化,并进一步研究了注射成型工艺条件对聚丙烯制品光泽度的影响。结果表明,在注射成型过程中,提高熔体温度、模具温度、保压压力及注射速率都有助于提高制品的光泽度,同时也会提高制品的拉伸强度和弯曲强度,但会降低缺口冲击强度。影响聚丙烯制品光泽度的最显著因素是熔体温度。影响因子的权重大小顺序为：熔体温度、模具温度、保压压力、注射速率。 相似文献
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Among the processing conditions of injection molding, temperature of the melt entering the mold plays a significant role in determining the quality of molded parts. In our previous research, a neural network was developed to predict the melt temperature in the barrel during the plastication phase. In this paper, a neural network is proposed to predict the melt temperature at the nozzle exit during the injection phase. A typical two-layer neural network with back propagation learning rules is used to model the relationship between input and output in the injection phase. The preliminary results show that the network works well and may be used for on-line optimization and control of injection molding processes. 相似文献
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注射成型温度对PP制品收缩率的影响 总被引：2，自引：0，他引：2
研究了影响聚丙烯（PP）制品收缩率的热膨胀、结晶和取向等因素，分别对制品模内收缩和后收缩的具体情况进行分析，揭示了注射温度和模具温度对PP制品收缩率的影响规律。 相似文献
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王刚 《现代塑料加工应用》2014,26(5):31-33
结合中沙(天津)石化有限公司450kt/a聚丙烯(PP)装置的工艺特点,选择氢调法试生产高流动抗冲PP EP5040粉料,同时添加专用添加剂得到刚韧平衡性较好的PP产品。随着产品性能进一步的完善,该产品将满足国内家电领域的需要,占领市场,缓解该类产品大量依靠进口的现状。 相似文献
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分析了PP-R（无规共聚聚丙烯）管材料MFR（熔体流动速率）的变化对力学性能的影响，着重通过双螺杆挤出机研究了PP—R管材料熔融挤出过程中影响MFR变化的因素。结果表明，合适的加工工艺控制和优良的抗氧体系是保证PP-R管材料加工过程中MFR稳定的前提。 相似文献
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采用注塑法生产出无规共聚聚丙烯(PPR)铜塑管件。讨论了铜件表面处理、铜件沟槽深度、注射压力、注射保压时间等工艺条件对PPR铜塑管件质量的影响。结果表明,当铜件表面经镀铬处理、铜件沟槽深度2.0mm、注射压力60MPa、塑化温度200℃、注射保压时间20s时,Dn63规格的PPR铜塑管件质量较理想。 相似文献
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螺杆构型与熔体温度均匀性关系密切,注射成型中的熔体温度均匀性直接影响注射制品的最终质量.通过注塑机塑化系统软件IMP模拟通用型螺杆、屏障型螺杆、分离型螺杆的轴向和径向温度分布,并对其进行对比,得出屏障型和分离型螺杆温度均匀性更好,更适合精度较高的注塑成型结论. 相似文献
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Wenyu Ma Zhengsheng Weng Minghui Wu Qian Ren Fei Wu Long Wang Wenge Zheng 《大分子材料与工程》2023,308(3):2200510
Foamed materials play an important role in a lightweight design. Foam injection molding (FIM) is an advanced and convenient way to fabricate lightweight structural materials. Recently, a new foam injection molding machine is developed, which only needs ultra-low gas pressure to fabricate microcellular foam. As a universal plastic, polypropylene (PP) is widely used due to its good mechanical properties. But after foaming, the toughness of the PP tends to decrease. Herein, a lightweight and high-impact polypropylene foam is fabricated via the new FIM technology with an ultra-low nitrogen pressure of 6.5 MPa. PP/polyolefin elastomer (POE) foam with a tiny cell size of 4.13 µm and high cell density of 2.7 × 109 cm−3 is successfully obtained. Owing to the superior cellular structure, compared with the pure PP foam, after adding the POE component, the maximum impact performance is increased by 465%. In this work, an easy-to-industrialized method for preparing lightweight and high-impact injection-molded PP foams are presented. 相似文献
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Moldflow在注射成型翘曲优化中的应用 总被引：3，自引：0，他引：3
赵龙志;陈炳辉;杨敏;张尚兵 《中国塑料》2010,24(5):78-80
以汽车卡扣座为例,用Moldflow软件对其注射成型过程进行模拟分析。通过分析材料种类、熔体温度和模具温度对翘曲的影响,确定了最佳浇口位置和最佳成型工艺参数。当采用牌号为PP-7553的聚丙烯、熔体温度为220 ℃、模具温度为40℃时的翘曲量最小,为0.1519 mm。 相似文献
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塑料注射成型中注射压力和熔体温度的快速预测 总被引：1，自引：0，他引：1
从黏性流体力学的基本方程出发，引入相关假设与简化，提出一种简化的注射流动计算模型，并采用有限差分法进行求解。在给定工艺参数（注射时间、注射温度、模具温度等）的条件下，该模型能快速、有效地预测塑料注射成型过程中的注射压力和最低熔体温度。最后，以一个数值算例来验证本文建立的预测模型和求解算法，其预测的注射压力和温度与CAE分析结果基本吻合，存在一定误差，而计算时间仅为CAE分析的0．03％。 相似文献
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In this study, a noninvasive and nondestructive ultrasonic technique has been used to monitor the polymer injection‐molding process in an attempt to establish a fundamental understanding of the processing/morphology/ultrasonic signal relationships. The ultrasonic technique not only can provide information on solidification affected by various temperatures and pressures but also can reflect the evolution of the crystal morphology and phase morphology of polymer blends. In addition, the periodic vibration of the dynamic‐packing injection‐molding process, in which the melt is 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, can also be monitored with the ultrasonic velocity and attenuation. Our results indicate that the ultrasonic technique is sensitive and promising for the real‐time monitoring of the injection‐molding process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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BACKGROUND: A low‐frequency vibration‐assisted injection‐molding (VAIM) device was developed to explore the morphology of high‐density polyethylene (HDPE) injection moldings. Scanning electron microscopy, wide‐angle X‐ray diffraction and differential scanning calorimetry were used to characterize structure‐property relationships of final products prepared under different VAIM processing conditions (vibration frequency and vibration pressure amplitude) with conventional injection molding for comparison. RESULTS: It was found that increasing the vibration frequency at constant vibration pressure amplitude was beneficial for obtaining ‘shish‐kebab’ structures in the core region of VAIM specimens, and increasing the vibration pressure amplitude at constant vibration frequency was a prerequisite for achieving HDPE specimens with large‐scale lamellas, more pronounced orientation and high crystallinity. CONCLUSION: Both preferred orientation lamellas and increased crystallinity allow one to obtain strong injection moldings with the application of the melt vibration technique. Copyright © 2009 Society of Chemical Industry 相似文献
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Fracture toughness characterized by the J-integral method has been evaluated along injection-molded bars of isotactic polypropylene. A significant increase in toughness with decreasing distance from the specimen gate has been observed with maximum steepness of the dependence in the central part of the specimen length. Parallel analysis of wide-angle X-ray diffraction patterns has shown a similar dependence of the crystalline β-phase concentration. It is suggested that polypropylene with β-crystallites has better structural continuity in the amorphous phase and, consequently, higher inherent ductility and superior macroscopic toughness than the related material containing only α-crystallites. Consequences of β-phase gradients for practical toughness testing are also discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2255–2259, 1998 相似文献
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Adel Jalaee;Kai Trottman;Victoria French;Sreenath Raghunath;Fernanda Brito dos Santos;E. Johan Foster; 《Polymer Composites》2024,45(14):12782-12795
Material extrusion and injection molding are prevalent in polymer processing, but wood fiber-reinforced polymer composites offer eco-friendly alternatives for industries like automotive, and aviation. Our study explores biocomposites using bleached chemi-thermomechanical pulp (BCTMP) and polypropylene (PP). BCTMP is rich in cellulose and hemicellulose and quite hydrophilic, while PP's hydrophobic structure creates a disconnect to creating a composite of the two. Traditional methods add costly coupling agents like maleic anhydride polypropylene (MAPP) in an attempt to enhance the adhesion properties of wood-plastic composites. However, it is worth noting that even in the presence of MAPP, PP maintains its high hydrophobicity and low surface energy, despite exhibiting considerable heterogeneity. Further complexity arises from the thermal degradation characteristics of BCTMP during the melting processing of PP. Our proposed method involves premixing via cryo and planetary ball milling. This boosts PP and BCTMP adhesion, enhancing dispersion quality and mechanical properties without needing coupling agents. Moreover, the premixing of BCTMP and PP forms a thermal buffer layer around BCTMP, minimizing its thermal degradation during processing. This process also ensures even distribution of BCTMP into PP, resulting in a 200% rise in Young's modulus with 30 wt% BCTMP without compromising ultimate tensile strength. 相似文献