Simultaneous polymerization and molding of pyrrone polymers

Our previously reported one-step method of simultaneously polymerizing and molding pyrrone monomers to produce high-strength, high-modulus, dense, thermally stable moldings has been studied in more detail and improved by using crystalline 1 : 1 salts of the monomers. Interrelationships between molding powder characteristics and molding conditions required to achieve optimum polymer properties were investigated. Typical properties of the moldings obtained from the salt of pyromellitic anhydride and 3,3′-diaminobenzidine were: density, 1.29 g/cc; diametral tensile strength, 10,700 psi; ultrasonic modulus, 1.3 × 10⁶ psi; hardness, 80 Rockwell B; and thermal stability in air (at 0.5°C/min), 400°C. Quick TGA methods, applied to the salts for estimating the thermal stability of molded polymers, before actual polymerization and molding, have been developed. No problems associated with gas release are observed when molding conditions have been optimized.     

注塑型酚醛模塑料热加工稳定性研究

讨论了低相对分子质量聚乙烯蜡、白油、切片石蜡及聚乙二醇4种稳定剂对酚醛注塑料热加工稳定性的影响，重点利用转矩流变仪研究了聚乙二醇加入前后酚醛注塑料的流变行为。结果表明：低相对分子质量聚乙烯蜡、白油、切片石蜡及聚乙二醇都可以有效地改善酚醛注塑料的流动性和热加工稳定性，但只有聚乙二醇不仅改善了酚醛注塑料的流动性和热加工稳定性，丽且还提高了酚醛注塑制品的弯曲强度。转矩时间流变曲线表明，加入聚乙二醇后酚醛注塑料具有更加宽泛的安全加工范围。     

基于矢量控制的全电动注塑机控制系统设计

根据全电动注塑机的工艺结构及对控制系统的要求,通过分析全电动注塑机的结构,在把矢量控制应用到永磁同步电机控制的基础上,提出了一种全电动注塑机控制系统的设计方案。经过分析和研究,表明该方案能够进一步提高全电动注塑机的精确控制能力,其稳定性好、可靠性高,能够较好地满足对全电动注塑机控制精度和稳定性的要求。     

基于矢量控制的全电动注塑机控制系统设计

根据全电动注塑机的工艺结构及对控制系统的要求,通过分析全电动注塑机的结构,在把矢量控制应用到永磁同步电机控制的基础上,提出了一种全电动注塑机控制系统的设计方案。经过分析和研究,表明该方案能够进一步提高全电动注塑机的精确控制能力,其稳定性好、可靠性高,能够较好地满足对全电动注塑机控制精度和稳定性的要求。     

Injection molding of PVC—today and tomorrow

Injection molding of PVC has been considered quite difficult because of the apparent low thermal stability with a high viscosity. While other materials were benefited by improved molding technology, technology applied to the molding of PVC received little attention. Whereas injection molding of PVC has been limited to general purpose pipe fittings, new resin technology and formulations provide compounds with excellent flow, easy molding characteristics and a good balance of physical properties.     

成型助剂对高效氨复合吸附剂强度稳定性的影响

对CaCl2/SiO2体系高效氨复合吸附剂的成型开展研究。从提高成型吸附剂初始强度和改善成型吸附剂孔结构两方面进行实验,考察了不同助剂对吸附剂强度稳定性的影响。结果表明,在成型过程中,通过加入助剂玻璃纤维明显提高了吸附剂初始强度,当玻璃纤维添加量为CaCl2/SiO2体系质量7%时,吸附剂初始强度提高了75%,但吸附剂强度稳定性表现差。通过向粘结剂CMC-Na中引入助剂Al(NO3)3交联成型的吸附剂具有更好的孔结构,对于一定的CaCl2/SiO2体系,当Al(NO3)3与CMC-Na质量比为0.6时,吸附剂多孔性能达到最优,吸附剂强度稳定性得到明显提升,且氨吸附量提高,吸附性能稳定。     

Molders' perceptions of vinyl injection molding compounds

As a result of advances in such properties as processability and thermal stability, vinyl may now compete with ABS and many engineering resins in a broad number of injection molding applications. However, do past experiences with PVC compounds prevent molders from quoting on new vinyl jobs? What do molders think of vinyl's physical properties and molding characteristics versus other resins? Independent research conducted in 1989 questioned a broad range of molders in the United States regarding their perception of vinyl versus other resins as an injection molding material. The results highlight the fact that molders are aware of the benefits of vinyl in finished part applications, but require training to overcome the perceptions of past molding experiences. This paper shares the results of this survey.     

微发泡注射成型工艺参数对制品尺寸稳定性的影响

研究了微发泡注射成型工艺对制品X方向和Y方向上尺寸稳定性的影响。采用信噪比作为评价指标,根据Taguchi实验设计方法对玻璃纤维增强聚丙烯进行实验。结果表明,影响制品尺寸稳定性的主要因素是玻璃纤维含量、注射速率和气体摩尔分数,合理的微发泡注射成型工艺可以明显地改善玻璃纤维增强型微发泡制品的尺寸稳定性。     

Effect of microstructure tuning by rapid heat cycle molding on the photodegradation behavior of isotactic polypropylene

Rapid heat cycling molding (RHCM) is an injection molding technique that improves the product quality of isotactic polypropylene (iPP) by tuning the microstructure, but its effect on the photodegradation stability remains to be investigated. In this work, the effect of RHCM tuned microstructure on the photodegradation behavior of iPP was investigated and compared with conventional injection molding (CIM). Differential scanning calorimetry (DSC), x-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), atomic force microscopy (AFM), and shore durometer (D scale) were used to examine the photodegradation behavior of iPP samples. The results showed that RHCM increased the crystallinity, crystal size, and β-crystal content of iPP samples. With the increase of photodegradation time, iPP samples injected with RHCM showed higher stability in terms of microstructure and surface quality. The relative changes in CI and R_a of RHCM90 were reduced by 48% and 40% after 800 h of UV irradiation, respectively. In addition, the combined results of dynamic mechanical analysis (DMA) and UV–visible absorption spectrum showed that RHCM promoted the development of crystalline structure and reduced the mobility of the surface chain segments as well as UV absorption coefficient. These combined effects contributed positively to its photodegradation stability.     

蓄能器在注塑机液压系统中的应用

阐述了蓄能器的工作原理、种类、功能、应用。从理论及应用方面,总结了蓄能器在注塑机节能系统中的应用现状。进一步强调了注塑机最主要的能耗是液压动力驱动系统的能耗,而蓄能器对注塑机液压系统的节约能源、保持工作稳定性等起着重要作用,所以研究蓄能器在注塑机液压系统中的应用是当前塑料机械一个非常重要研究方向。最后展望了蓄能器在注塑机液压系统中的应用前景。     

Selecting the conditions of molding iron oxide catalysts for dehydrogenation

The effect of the conditions for molding iron oxide catalysts for dehydrogenation of iso-amylenes to isoprene on their operation characteristics was studied. The investigation of laboratory samples allowed us to determine the optimum molding pressure (200–250 MPa) under which high mechanical strength (strength factor K _G = 33.4–37.3 N/mm), the stability of the kinetic characteristics in the dehydrogenation reaction, and the formation of 15–50 nm pores, ensuring the occurrence of the process in the kinetic region, were attained. we propose using the extrudate density as an indirect criterion for estimating the molding pressure under industrial conditions of extrusion. It was shown that in order to develop high strength properties (K _G ∼ 29.1 N/mm) of the catalysts upon their production under industrial conditions and to ensure the occurrence of the reaction in the kinetic region, the extrudate density must be 2.40–2.46 g/cm³. The obtained results were verified via paste molding on various industrial extruders, thereby enabling us to recommend the type of molding extrusion equipment.     

模具电火花线切割加工稳定性综合分析

本文从模具材料的选择、线切工艺、实时加工等方面综合分析了影响模具电火花线切割加工稳定性的各种因 素，从而提高现有机床设备的加工精度。     

浅谈滚塑工艺在钢衬塑储罐方面的技术与应用

随着滚塑工艺的成熟发展,特别是在滚塑钢衬塑储罐以及化工防腐设备等领域的应用非常广泛,并具有强力的市场需求。这一技术的应用凸显了它的工艺结构、特点、原材料、生产设备等方面的独特优势,对产品性能、质量的稳定有了很大提高。本论文以滚塑成型工艺技术在钢衬塑产品方面的应用为分析对象,在理论与实践的基础上,对滚塑钢衬塑工艺技术、特点、原材料、成型设备、衬塑方案以及常见问题的解决方法,逐一进行了论述和总结,可为相近类型企业生产提供参考。     

Reaction injection molding (RIM) elastomers having superior high temperature performance

Reaction injection molding (RIM) elastomers are being seriously considered by major automotive companies as a substitute for metal in exterior body panels. One major consideration in this application is dimensional stability at a 325°F paint bake cycle. Reported here are formulations which via novel processing result in finished parts with excellent dimensional stability at 325°F. In addition, other properties such as impact resistance and flex modulus ratio improve parallel with high temperature performance. Mechanical properties as a function of processing and molding parameters are presented. Other studies are presented and a tentative explanation of the superior performance of these RIM elastomers is made.     

Polymerization of aromatic nuclei. XIII. X-ray analysis and properties of poly(p-phenylene) pellets

X-ray diffraction experiments with poly(p-phenylene) pellets demonstrated an increase in crystallinity with increase in molding temperature or annealing temperature. The increase in crystallinity may be attributed to annealing effects and loss of chlorine under severe conditions. Lattice constants for the crystalline polymer are presented, and the crystallographic data are compared with those of the lower oligomers. Poly(p-phenylene) was investigated also in relation to oxidative thermal stability, chemical and solvent resistance, and the effect of temperature and variation in molding conditions on fracture strength. The decrease in strength at elevated temperatures appears to be related to the increase in crystallinity.     

旋转模塑防水包装箱专用树脂的研究及应用

用一种高密度聚乙烯分别与两种线形低密聚乙烯进行共混制备了两种旋转模塑聚乙烯专用树脂，并使用双轴旋转模塑机生产了两种规格的大型中空制品，研究了不同质量配比对共混树脂力学性能的影响；通过红外光谱、扫描电镜、X射线衍射分析了旋转模塑制品的热稳定性及不同成型温度和风冷时间下的微观结构，制品经垂直冲击跌落、正弦定频垂直振动、耐压力、高低温和空投试验考察了旋转模塑制品的环境适应性。实验结果表明，经共混改性得到的两种原料可以作为旋转模塑专用树脂。     

Effect of the method of fabrication of polyvinyl alcohol films on the properties of immobilized trypsin

In order to develop a film wound dressing with proteolytic activity based on polyvinyl alcohol, the effect of the conditions of the preparation of the molding solution on the properties of trypsin immobilized in the film structure was studied. The dependence of the relative activity and enzyme stability on the order of the introduction of the components into the molding solution and the molecular weight of the polyethylene glycol additives was established.     

A novel method for improving the surface quality of microcellular injection molded parts

Microcellular injection molding is the manufacturing method used for producing foamed plastic parts. Microcellular injection molding has many advantages including material, energy, and cost savings as well as enhanced dimensional stability. In spite of these advantages, this technique has been limited by its propensity to create parts with surface defects such as a rough surface or gas flow marks. Methods for improving the surface quality of microcellular plastic parts have been investigated by several researchers. This paper describes a novel method for achieving swirl-free foamed plastic parts using the microcellular injection molding process. By controlling the cell nucleation rate of the polymer/gas solution through material formulation and gas concentration, microcellular injection molded parts free of surface defects were achieved. This paper presents the theoretical background of this approach as well as the experimental results in terms of surface roughness and profile, microstructures, mechanical properties, and dimensional stability.     

全液压内循环二板式注塑机性能特点及锁模精度研究

全面深入地分析了新型全液压内循环二板式注塑机的性能特点,并对合模机构的锁模性能进行研究.新型二板式注塑机采用内循环式的舍模油缸,省去液压油外部循环过程并简化液压系统结构,节能、节材效果显著.移模和锁模动作分别采用不同油缸,解决了力与速度的关系,锁模特性优异,成型性能稳定性高.机器配备伺服电机驱动定量泵的动力系统,节能降耗,噪音低.合模机构锁模力的测试结果表明:2000 kN试验机台的锁模力符合设计要求;新型内循环二板式注塑机比同规格的肘杆三板机具有更优异的锁模性能,在最大锁模力情况时,前者比后者的锁模力重复精度高出0.33‰,为注射成型精密化提供保证.     

Properties,environmental stability,and molding characteristics of polyphenylene sulfide

Polyphenylene sulfide is a new engineering plastic characterized by a unique combination of useful environmental, mechanical, and flame resistant properties. This paper presents a variety of new developments in molding methods and long term properties of polyphenylene sulfide. Optimum conditions for fabrication by injection molding, compression molding, and free sintering techniques are described along with a comprehensive tabulation of mechanical, factional, and electrical properties of various filled and unfilled compositions. The effect of injection molding conditions and post-treatments, such as annealing, on mechanical behavior is discussed. Long term stability of molded specimens of the polymer to a variety of chemical environments as well as oven aging studies are reported. The significance of these properties is illustrated by a discussion emphasizing new applications for various compositions based on polyphenylene sulfide.