玻璃纤维增强PA66制品翘曲变形的研究

针对玻璃纤维增强尼龙66（PA66／GF）注射成型制品存在的翘曲变形缺陷,运用Moldflow MPI软件对PA66／GF进行了注射成型模拟分析。结果表明,GF的取向是影响PA66／GF注射成型制品翘曲变形的主要原因;增加制品厚度或增设浇口均可有效减小制品的翘曲变形.     

DR在聚醚醚酮注射制品缺陷检测中的应用

介绍了X射线数字成像检测(DR)技术及其特点,对热塑性工程塑料聚醚醚酮(PEEK)注射成型制品进行了DR检测,给出了PEEK注射制品内部典型缺陷气泡和夹杂的DR图像特征,并采用计算机断层扫描技术(CT)对检测结果进行了验证。研究表明,DR技术能够快速、准确、清晰地检测出PEEK注射制品内部缺陷;分析产生缺陷的原因,结合实际情况提出了避免缺陷产生的改进措施。     

注塑工艺对钛酸钾晶须改性POM和PA66共混体系力学性能的影响

用注塑成型方法制备了聚甲醛(POM)、钛酸钾晶须改性POM复合材料(ZA343)、PA66及钛酸钾晶须改性PA66复合材料(ZN262B)样品,运用控制变量法考察了工艺参数对其力学性能的影响。结果表明:ZA343和ZN262B相对于POM和PA66的拉伸强度分别提高53.8%和87.1%。当注射温度为210℃、模具温度为90℃、注射压力为55 MPa时,ZA343的拉伸强度最大为89.1 MPa;当注射温度为315℃、模具温度为60℃、注射压力为60 MPa时,ZN262B的拉伸强度最大为127.6 MPa。     

微流控芯片注射紫外光固化成型中缺陷形成机理及解决方案研究

提出了一种微流控芯片的新型成型方法——紫外(UV)光固化微注射模塑成型,微通道"十"字处和整个基体表面的气泡为其成型的主要缺陷,对后续芯片的使用将会造成很大影响;利用可视化实验研究分析了缺陷的形成原因,并研究了各工艺(注射压力、抽真空、注射方式、光照方式等)对缺陷改善的影响。结果表明,注射方式对"十"字处气泡的形成影响最大,光照方式对基体表面气泡的形成影响最大,通过选用适当的注射方式和光照方式,能够完全解决"十"字处和基体上的缺陷。     

气体辅助注射成型中溢料井对翘曲的影响

采用数值模拟和正交实验方法对聚丙烯(PP)气体辅助注射成型(GAIM)制品的翘曲缺陷进行分析,分别研究了气体注射延迟时间、气体注射压力等工艺参数以及设计辅助溢料井结构影响因素之间的交互作用对GAIM制品翘曲变形缺陷的影响。结果表明,气体注射压力与溢料井结构的相互关系是影响翘曲程度的关键;选择合适的注射压力和设计辅助溢料井结构可以显著降低制品翘曲变形的程度。     

MBS制品注射成型工艺探讨

从工艺特性、模具设计、制品设计等方面探讨了(甲基丙烯酸甲酯/丁二烯/苯乙烯)共聚物(MBS)制品的注射成型技术,结合典型MBS碱性蓄电池壳介绍了注射成型中的各种工艺参数,并对MBS蓄电池壳加工中的缺陷、原因及解决方法进行了论述。     

热塑性聚氨脂过滤器壳制品常见的缺陷及解决方法

介绍了利用热塑性聚氨酯弹性体(TPU)原料制造过滤器壳体注射成型的工艺流程。对生产过滤器壳体制品的缺陷及解决方法进行了深入的分析、总结。列举了过滤器壳体注射成型过程中常见的欠注、流痕、银纹、溢料、制品应力和缩凹变形等缺陷,从影响制品质量的各个因素,如注射成型工艺、模具及产品设计等方面入手,分析其成因并提出了相应的解决方法。     

聚砜注塑工艺及制品缺陷对策

介绍了聚砜(PSU)的结构、性能,并结合制品设计、模具设计等对PSU的注射成型要点进行了讨论。详细分析了PSU的注塑工艺参数,系统阐述了PSU在注射成型中常见的缺陷及解决方法。     

热塑性塑料注射成型时常见缺陷、产生原因及解决措施

本文介绍了热塑性塑料在注射成型中最为常见的缺陷,分析了可能产生缺陷的各种原因,并从改进模具结构、成型工艺过程控制(包括温度,压力,时间等)以及对原料进行预干燥处理等方面,提出了相关的解决措施。     

纤维增强PA66注塑熔接痕性能的工艺优化

针对注塑过程中纤维增强PA66制品出现的熔接痕缺陷,利用Taguchi方法设计了L9实验矩阵,分析了注塑压力、熔体温度、注射速率和保压压力等工艺因素对注塑件熔接痕拉伸强度的影响,预测了最大拉伸强度和最佳工艺条件,与实验结果具有很好的一致性。     

Flow synthesis of a novel zirconium-based UiO-66 nanofiltration membrane and its performance in the removal of p-nitrophenol from water

In this work, a thin zirconium-based UiO-66 membrane was successfully prepared on an alumina hollow fiber tube by flow synthesis, and was used in an attempt to remove p-nitrophenol from water through a nanofiltration process. Two main factors, including flow rate and synthesis time, were investigated to optimize the conditions for membrane growth. Under optimal synthesis conditions, a thin UiO-66 membrane of approximately 2 µm in thickness was fabricated at a flow rate of 4 mL·h⁻¹ for 30 h. The p-nitrophenol rejection rate for the as-prepared UiO-66 membrane applied in the removal of p-nitrophenol from water was only 78.1% due to the existence of membrane defects caused by coordinative defects during membrane formation. Post-synthetic modification of the UiO-66 membrane was carried out using organic linkers with the same flow approach to further improve the nanofiltration performance. The result showed that the p-nitrophenol rejection for the post-modified membrane was greatly improved and reached over 95%. Moreover, the post-modified UiO-66 membrane exhibited remarkable long-term operational stability, which is vital for practical application.     

锦纶66帘布压延工艺控制及常见质量问题解决措施

介绍轮胎用锦纶66帘布压延过程及其工艺控制、压延帘布常见质量问题及其解决措施。严格控制热炼胶塑性值和供胶温度、保证原帘布干燥、导开帘布松紧一致、帘布对中、供胶和递布稳定、帘布压延张力和压延速度合理和均衡、压延机辊温和帘布冷却辊温稳定、压延机积胶量适当、压延帘布卷取协调性好,以及严格工艺操作,可以有效解决压延帘布幅宽和厚度不合格、扒皮、露白、罗股、劈缝、跳线、出兜、压坏和褶子等质量问题。     

塑料在汽车滤清器中的应用

针对汽车滤清器用金属材料特别是黑色金属材料存在密度大、易腐蚀、不耐磨、加工工艺要求高等缺点,采用改性聚丙烯、增强尼龙66、(丙烯腈／丁二烯／苯乙烯)共聚物(ABS)、聚甲醛等改性塑料和工程塑料制备了滤清器中的叶片环、扩散锥、汽油滤清器外壳、空气滤清器外壳、旋流管、中心管等部件,既提高了生产效率,又降低了成本,经济效益显著。     

Torque rheometry and rheological analysis of powder–polymer mixture for aluminum powder injection molding

Selection of desired powder–polymer mixture (feedstock) formulation is a key factor in manufacturing perfect parts via powder injection molding. In the present study, feedstock characteristics of an aluminum-based powder were investigated by torque rheometry and rheological analyses. Several binders containing various amounts of polypropylene (PP), paraffin wax (PW), and stearic acid (SA) were selected for torque mixing and viscosity evaluation. Then, feedstocks consisting of 54, 58, 62, and 66 vol. % solid contents were prepared with modified binder. Feedstock flow behaviors were investigated regarding the rheological parameters such as mixing torque, viscosity, flow behavior index, flow activation energy and moldability index. It was found that increasing solid loading from 54 to 62 vol. % led to improved rheological behavior. This improvement was not observed in high solid contents, i.e., 66 vol. %. Based on experimental results, the optimized binder composition (60PW,35PP,5SA vol. %) and the optimum powder loading (62 vol. %) were selected as the best formulations for injection of aluminum powder. These values are supported by critical powder volume concentration measurements deduced from the oil absorption method. The resulting aluminum molded green parts with no defects exhibited the straightforward injection molding process of selected feedstock.     

Deformation of dispersed PA66 phase in drawn PA66/SAN blend

Polyamide 66/styrene acrylonitrile (PA66/SAN) drawn strands were prepared by stretching the corresponding extrudates at 130 °C. During stretching, the PA66 droplets in the extrudate are deformed as a result of the stretching-induced stress. In drawn strands, the morphology of the deformed PA66 is greatly affected by the morphology of the PA66 dispersed phase in the extrudate as well as by the interfacial adhesion between the PA66 and SAN matrix. Upon stretching, the cylindrical PA66 threads in the uncompatibilized extrudate [styrene acrylonitrile maleic anhydride (SANMA) as compatibilizer] deform into PA66 fibrils with large aspect ratio, while the small spherical PA66 droplets are only slightly deformed. Interfacial adhesion between the PA66 and SAN is improved in the compatibilized PA66/SAN extrudate. Consequently, despite the small diameter, PA66 droplets in the compatibilized blend are greatly deformed during stretching.     

The effects of processing variables on stress development in ultraviolet-cured coatings

A cantilever deflection technique was used to monitor stress development during ultraviolet photo-cure of acrylate coatings to the glassy state. Two coating systems were studied: a trifunctional monomer (trimethylol propane triacrylate, TMPTA) and a tetrafunctional monomer (pentaerythritol tetraacrylate, PETA). Both were photoinitiated with 2,2-dimethoxy-2-phenylacetophenone (DMPA). Average in-plane stresses of up to 30 MPa were measured upon curing at room temperature. The rate and magnitude of stress development rose with the photoinitiator concentration and with light intensity. Curing with more strongly absorbed light had similar effects. Light absorption caused decreased stress magnitudes in thicker coatings. Somewhat unexpectedly, the rate and magnitude of stress development increased with monomer functionality even though the conversion fell. Moreover, curing thick coatings with high radical concentrations (strongly absorbing light and large photoinitiator concentrations) caused ripple defects to form. With the appearance of these defects, stress ceased to rise with the photoinitiator concentration. Fourier transform infrared spectroscopy was employed to monitor conversion and to help understand these stress development trends. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1267–1277, 1997     

Hydroxyl Defect Effect on Reoxidation of Sc‐Doped (Ba,Ca)(Ti,Zr)O3 Fired in Reducing Atmospheres

The behavior of grain and grain‐boundary conductivity of acceptor (Sc)‐doped (Ba,Ca)(Ti,Zr)O₃ ceramics sintered in moist reducing atmosphere and subsequently reoxidized in dry and moist atmosphere was investigated by means of impedance spectroscopy (IS). In moist firing atmosphere, water vapor was found to react with oxygen vacancies, forming positively charged hydroxyl defects on regular oxygen sites in the crystal lattice. Proton hopping is considered to raise the ionic conductivity significantly. Therefore, hydroxyl defects in turn influence the grain conduction. Hydroxyl defects are also considered to be responsible for alternations of the dielectric maximum at the Curie point.     

PA66/EPDM-g-MAH/CaCO_3复合材料的性能

采用熔融挤出过程中改变螺杆转速和添加引发剂的复合引发方法制备了马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH),将其单独或与CaCO_3混合后改性聚酰胺66(PA66)。通过滴定分析、红外表征和熔体流动速率(MFR)测定等方法研究了175℃条件下螺杆转速对EPDM-g-MAH的MFR和接枝率的影响。探讨了接枝物和CaCO_3对PA66力学性能、热变形温度的影响。研究结果表明,改变螺杆转速可以有效控制接枝物凝胶含量(1%),提高接枝率和MFR;当接枝物用量为30份时,PA66/EPDM-g-MAH复合材料的简支梁缺口冲击强度为34.24 k J/m2,是纯PA66的3.89倍;当CaCO_3用量小于15份时,两种CaCO_3与EPDM-g-MAH均能够协同增韧PA66,当PA66/EPDM-g-MAH/CaCO_3配比为100/30/10时,加入超细活性重质CaCO_3及纳米CaCO_3的复合材料的简支梁缺口冲击强度均达到最大值,分别为纯PA66的4.35倍和4.10倍,超细活性重质CaCO_3的作用优于纳米CaCO_3。超细活性重质CaCO_3用量为20份时,PA66/EPDM-g-MAH复合材料的弯曲强度、热变形温度及MFR最佳,分别为59.42 MPa、81.6℃及9 g/(10 min)。     

Polyaniline/multi-walled carbon nanotube composites with core-shell structures as supercapacitor electrode materials

Composites with core-shell structures consisting of polyaniline and carbon nanotubes were prepared via in situ polymerization of aniline monomers by using multi-walled carbon nanotubes with minimized defects as templates. The strong interaction in such conjugated systems greatly improves the charge-transfer reaction between polyaniline and the carbon nanotube. Influences of the thickness of the polyaniline layer on the surface of the carbon nanotubes on the electrochemical properties of the resulting composites are discussed. The highest specific capacitance of 560 F/g was achieved by using a composite with 66 wt% polyaniline content as the supercapacitor electrode. Additionally, enhancement of the capacity retention was observed, with the composite losing only 29.1% of the maximum capacity after 700 cycles, and then remaining stable.     

MCA不同加料方式对尼龙66力学性能的影响

在双螺杆挤出改性工艺下,研究了不同的加料方式下三聚氰胺氰尿酸盐(MCA)填充尼龙66材料的弯曲和缺口冲击性能的变化。对材料进行弯曲、冲击试验测试。结果表明,侧喂料的弯曲模量比主喂料的结果低以及侧喂料的悬臂梁缺口冲击强度比主喂料的高。其主要原因是由于一定比例条件下主喂料的分散性较好,而MCA在加工过程以及最后改性材料中呈刚性片状颗粒的状态。因此MCA材料分散越是均匀材料的刚性越好。另外MCA粒子的粒径较大,因此材料在成型过程中分散越均匀,材料里面应力缺陷点越多,导致材料的冲击性能下降。