Effects of mold cavity temperature on surface quality and mechanical properties of nanoparticle‐filled polymer in rapid heat cycle molding

Acrylonitrile‐butadiene‐styrene (ABS)/poly methyl methacrylate (PMMA) and ABS/PMMA/nano‐CaCO₃ composites were prepared in a corotating twin screw extruder. Single‐gate and double‐gate samples were molded based on a rapid heat cycle molding (RHCM) system. Effects of mold cavity temperature on surface quality and mechanical properties of single‐gate and double‐gate samples in RHCM process were conducted. The results showed that surface quality of plastic parts can be improved significantly by increasing mold cavity temperature. Nano‐CaCO₃ particles on the surface of plastic parts can be eliminated by using high mold cavity temperature. The roughness and gloss of two kinds of plastic parts (ABS/PMMA and ABS/PMMA/nano‐CaCO₃) stabilized at the same level when the mold cavity temperature is above glass transition temperature of resin material. Weld line can be eliminated in RHCM process during high mold cavity temperature. The tensile strength of both ABS/PMMA and ABS/PMMA/nano‐CaCO₃ exhibited decreasing trend with the increase of mold cavity temperature. Reduction of internal stress gave rise to the increase of Izod impact strength of ABS/PMMA for both sing‐gate and double‐gate samples. However, influence regularity of mold cavity temperature on Izod impact strength of ABS/PMMA/nano‐CaCO₃ is depended on the number of gates. For all the samples in this study, too high of mold cavity temperature (higher than 125°C) deprave Izod impact strength of plastic parts. Both ABS/PMMA and ABS/PMMA/nano‐CaCO₃ are not susceptible to weld line. When the mold surface temperature is approximately equal to glass transition temperature of resin material, all the samples are found to give the best combination of properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41420.     

Application of porous oxide layer in plastic/metal direct adhesion by injection molding

In this study, porous oxide layers were coated on aluminum sheets by plasma electrolytic oxidation (PEO) treatment. The PEO-treated aluminum sheets were then inserted and direct heated in the injection mold. The melting plastic penetrated and solidified in the micropores during the injection molding process, consequently achieving plastic/metal direct adhesion through micro-mechanical interlocking. The effects of the different surface morphologies of PEO coatings on plastic/metal adhesion were studied by shear test and microscopic characterizations. The microstructures were varied by changing PEO process parameters. The bonding strength was affected by the surface morphology changes, and the experimental results show that the surface porosity is a major factor in the direct adhesion. Reliable joints can be achieved on the porous coating, and the strength was proportional to the surface porosity. The shear strength in this study was in a range of approximately 3–8 MPa with 7–20% surface porosity.     

Properties of glass‐filled thermoplastic polyesters

The thermal, mechanical, and rheological properties of glass‐filled poly(propylene terephthalate) (GF PPT) were compared to glass‐filled poly(butylene terephthalate) (GF PBT). The impetus for this study was the recent commercial interest in PPT as a new glass‐reinforced thermoplastic for injection‐molding applications. This article represents the first systematic comparison of the properties of GF PPT and GF PBT in which differences in properties can be attributed solely to differences in the polyester matrices, that is, glass‐fiber size and composition, polymer melt viscosity, nucleant content and composition, polymerization catalyst composition and content, and processing conditions were kept constant. Under these controlled conditions, GF PPT showed marginally higher tensile and flexural properties and significantly lower impact strength compared to GF PBT. The crystallization behavior observed by cooling from the melt at a constant rate showed that GF PBT crystallized significantly faster than did GF PPT. Nucleation of GF PPT with either talc or sodium stearate increased the rate of crystallization, but not to the level of GF PBT. The slower crystallization rate of GF PPT was found to strongly affect thermomechanical properties of injection‐molded specimens. For example, increasing the polymer molecular weight and decreasing the mold temperature significantly increased the modulus drop associated with the glass transition. In contrast, the modulus–temperature response of GF PBT was just marginally influenced by the polymer molecular weight and was essentially independent of the mold temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 889–899, 1999     

某医疗器械带金属嵌件塑件的注塑模具设计

以某医疗器械带金属嵌件塑件为研究对象,运用注塑成型技术进行注塑模具设计.针对产品的多规格及系列化特点,创新设计了浇注系统,可以根据需求成型不同规格产品.通过分析塑件的结构特征,设计了组合式型芯、哈夫机构、推出机构,实现嵌件刀片的精准定位,完成塑件成型和自动脱模.将立式注塑机工作台,由一个工位改造成两个工位,既能方便地取...     

低温等离子处理ABS的预电镀性能研究

通过低温等离子体表面处理对丙烯腈-丁二烯-苯乙烯（ABS）表面进行刻蚀;以乙烯基三甲氧基硅烷、γ-巯丙基三甲氧基硅烷、γ-氨丙基三乙氧基硅烷为主体的无钯敏化、活化液对ABS进行表面镀镍,通过傅里叶变换全反射红外光谱（ATR-FTIR）、接触角测量仪和扫描电子显微镜（SEM）等探究了电镀ABS的性能,并根据GB/T 9286—2021,用90°黏合强度测试法测试塑料与金属层之间的黏附牢固程度。结果表明,当处理时间为300 s、功率为600 W时,ABS电镀预处理效果最佳,此时结合强度达到0.94 kN/m。     

Development of polymer‐molding‐releasing metal mold surfaces with perfluorinated‐group‐containing polymer plating

The polymer‐molding‐releasing properties of metal molds were found to be related to the following factors: (1) interfacial chemical bonding between the surfaces of polymers and metal molds and (2) a friction force or friction coefficient between polar substances and/or low‐molecular‐weight components in the polymers and physical factors on mold surfaces. We theoretically and experimentally confirmed that metal molds with good polymer‐molding‐releasing properties had very small surface free energies. We also proved that the surface free energies in the resulting polymer moldings were lower than before shaping. The molding releasing properties improved with decreasing friction force and friction coefficient between the surface of polymers and metal molds and with decreasing surface free energy. To obtain metal molds with lower surface free energies, we developed a polymer plating method with perfluorinated‐group‐containing triazine dithiol. The Metal mold treated by polymer plating had lower critical surface tension (7.5 mJ/m²) than Teflon (18 mJ/m²), indicating that the surface consisted of CF₃ ? groups. The treated mold showed excellent durability in its releasing properties, which was better than that of the untreated mold. This technique was developed for the production of molds for the Fθ lens and the naturally bright focusing screen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2549–2556, 2003     

Mechanical Properties of Carbon Epoxy Prepreg Insert Phenolic Resin Injection Moldings

This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy(CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic resin(GF/PF). The CF/Epoxy was placed in the mold cavity prior to injecting GF/PF onto the inserted injection molded CF/Epoxy specimens. The role of adhesion between the inserted part and injected resin on the mechanical properties was evaluated by 3 point bending and impact tests. In addition, the effect of prepreg orientation on the mechanical properties of the prepreg inserted-injection molding system was investigated. It was found that the prepreg with unidirectional orientation significantly improved flexural and impact strength of the inserted injection molding composites, providing better support and resistance to bending and impact loading. The main failure modes of the specimens were structural and adhesive failure.     

电子行业用聚酯热熔胶的制备及其性能研究

以玻璃化转变温度较低的共聚酯制备了聚酯热熔胶。研究结果表明:聚酯热熔胶对丙烯腈-丁二烯-苯乙烯共聚物(ABS)、聚碳酸酯(PC)等极性塑料与金属材料具有良好的粘接性能,稳定后的剥离强度大于100N/25mm;同时,具有良好的耐老化性能及粘接持久性。聚酯热熔胶可取代国外产品用于电子行业用极性聚合物与金属材料粘接。     

Experimental investigation and numerical simulation of injection molding with micro‐features

Injection molding of thin plates of micro sized features was studied in order to manufacture micro‐fluidic devices for bioMEMS applications. Various types of mold inserts—CNC‐machined steel, epoxy photoresist, and photolithography and electroplating produced nickel molds—were fabricated and tested in injection molding. The feature size covers a range of 5 microns to several hundred microns. Issues such as surface roughness and sidewall draft angle of the mold insert were considered. Two optically clear thermoplastics, PMMA and optical quality polycarbonate, were processed at different mold and melt temperatures, injection speeds, shot sizes, and holding pressures. It was found that the injection speed and mold temperature in injection molding greatly affect the replication accuracy of microstructures on the metal mold inserts. The UV‐LIGA produced nickel mold with positive draft angles enabled successful demolding. Numerical simulation based on the 2D software C‐MOLD was performed on two types of cavity fillings: the radial flow and the undirectional flow. The simulation and experimental data were compared, showing correct qualitative predictions but discrepancies in the flow front profile and filled depth.     

Film insert molding as a novel weld‐line inhibition and strengthening technique

Specimens with weld lines were produced via conventional and film insert molding techniques using two types of materials as the substrate resin, i.e. a polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) blend and glass fiber‐filled polycarbonate (PC‐gf). The formation and morphology of the weld line region was assessed with and without the presence of 0.5‐mm‐thick PC film inserts. The weld line formation and characteristics were found to be dependent on the extent of interaction between the injected resin and the mold surface or the film insert. Better interfacial interaction between the substrate and film led to the distortion of the weld line orientation, which significantly enhanced the mechanical properties of the weld line. The incorporation of glass fibers into the substrate resin would usually reduce the resistance of the weld line towards tensile, flexural and impact loadings. However, with the attachment of film inserts, the mechanical properties of the weld line region have significantly improved, even with the presence of rigid fibers. Upon examination of tensile and impact fracture surfaces of film insert specimens, a unique orientation of fibers across the weld line (parallel to the flow direction and perpendicular to the weld line) could be observed at regions directly under the film. The combination of favorable properties from the unique fiber orientation and distortion of the weld line, as well as the ability of the film to effectively dissipate forces towards a larger area, have synergistically contributed towards the mechanical property enhancement of the weld line region in film insert moldings. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

The occurrence of surface roughness in gas assist injection molded nylon composites

Gas assist injection molding has increasingly become an important industrial process because of its tremendous flexibility in the design and manufacture of plastic parts. However, there are some unsolved problems that limit the overall success of this technique. The purpose of this report was to study the surface roughness phenomenon occurring in gas assist injection molded thermoplastic composities. The materials used were 15 % and 35% glass‐fiber filled nylon‐6 composites. Experiments were carried out on an 80‐ton injection molding machine equipped with a high‐pressure nitrogen‐gas injection unit. Two “float‐shape” axisymmetric cavities were used. After molding, the surface quality of molded parts was measured by a roughness meter. Various processing variables were studied in terms of their influence on formation of surface roughness: melt temperature, mold temperature, melt filling speed, short‐shot size, gas pressure, and gas injection delay time. Scanning electronic microscopy was also employed to characterize the composites. It was found that the surface roughness results mainly from the exposure of glass fiber in the matrix. The jetting and irregular flows of the polymer melt during the filling process might be factors causing the fiber exposure.     

水溶性芯模在VARI成型工艺中的应用研究

制备了一种低成本易成型的水溶性芯模,对其成型收缩率、压缩性能、水溶性及气密性进行了研究,结果表明采用石英砂制备的可溶性芯模成型前后具有良好的尺寸稳定性,在室温至120℃区间内压缩强度均高于3 MPa,浸泡在常温水溶液中1 min内能够快速溃散至砂粒状态,经表面封孔处理后能够达到VARI成型工艺对模具的气密性要求。通过在填充可溶性芯模的中空金属框表面进行VARI工艺验证试验,表明制备的水溶性芯模能够作为VARI工艺模具使用,且脱模简单方便,对制品表观质量基本没有影响,具有良好的应用前景。     

Thermal response of an electric heating rapid heat cycle molding mold and its effect on surface appearance and tensile strength of the molded part

Rapid heat cycle molding (RHCM) is a newly developed injection molding technology in recent years. In this article, a new electric heating RHCM mold is developed for rapid heating and cooling of the cavity surface. A data acquisition system is constructed to evaluate thermal response of the cavity surfaces of the electric heating RHCM mold. Thermal cycling experiments are implemented to investigate cavity surface temperature responses with different heating time and cooling time. According to the experimental results, a mathematical model is developed by regression analysis to predict the highest temperature and the lowest temperature of the cavity surface during thermal cycling of the electric heating RHCM mold. The verification experiments show that the proposed model is very effective for accurate control of the cavity surface temperature. For a more comprehensive analysis of the thermal response and temperature distribution of the cavity surfaces, the numerical‐method‐based finite element analysis (FEA) is used to simulate thermal response of the electric heating RHCM mold during thermal cycling process. The simulated cavity surface temperature response shows a good agreement with the experimental results. Based on simulations, the influence of the power density of the cartridge heaters and the temperature of the cooling water on thermal response of the cavity surface is obtained. Finally, the effect of RHCM process on surface appearance and tensile strength of the part is studied. The results show that the high‐cavity surface temperature during filling stage in RHCM can significantly improve the surface appearance by greatly improving the surface gloss and completely eliminating the weld line and jetting mark. RHCM process can also eliminate the exposing fibers on the part surface for the fiber‐reinforced plastics. For the high‐gloss acrylonitrile butadiene styrene/polymethyl methacrylate (ABS/PMMA) alloy, RHCM process reduces the tensile strength of the part either with or without weld mark. For the fiber‐reinforced plastics of polypropylene (PP) + 20% glass fiber, RHCM process reduces the tensile strength of the part without weld mark but slightly increases the tensile strength of the part with weld mark. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

玻纤增强ABS复合材料的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及玻璃纤维(GF)为原料,以环氧树脂作为界面相容剂,研究了界面相容剂对玻璃纤维增强ABS复合材料力学性能及界面粘接的影响.结果表明:加入环氧树脂,玻纤增强ABS复合材料的力学性能明显提高;随着玻纤质量分数的增加,复合材料的拉伸强度、弯曲强度、冲击强度均逐渐增加;玻纤质量分数为30%时,GF/ABS/环氧树脂复合材料的拉伸强度比未改性的复合材料的拉伸强度提高了30%,弯曲强度提高了25%,冲击强度也提高了50%.     

Characterization of a reverse molding sequence at the mesoscale for in‐mold assembly of revolute joints

In‐mold assembly and miniature molding have been combined to realize miniature assemblies. Our previous work has shown that for realizing in‐mold assembly at the mesoscale, the molding sequence is the reverse of that used at the macroscale. Moreover, special features are needed in the mold to prevent plastic bending of the pin because of the pressure exerted by the second stage melt. This article presents novel mold designs and computational methods to enable the use of the reverse molding sequence to prevent: (1) plastic bending of the premolded component, and (2) joint jamming during the mesoscale in‐mold assembly process. The computational methods are also validated through experimentation. Results reported in this article show that for making in‐mold assembled revolute joints with the polymer combination of ABS and LDPE, a reversed molding sequence needs to be used for joints sizes less than 1.5 mm. POLYM. ENG. SCI., 50:1843–1852, 2010. © 2010 Society of Plastics Engineers     

Contact angle and wettability of hybrid surface-treated metal adherends

Adhesion performance of adhesively bonded metal joints with aluminum and stainless steel was much dependent on the surface treatment of the adherends. This work was aimed at optimizing hybrid surface treatments to improve wettability of metal surfaces and strength of adhesive metal joints, which was a combination of mechanical, chemical, and energetic surface treatment methods. The surface free energies and wettability of hybrid surface-treated metal adherends were measured for different treatment conditions with abrasion, grit blast, sulfuric acid etching, phosphoric acid anodizing, silane treatment, plasma treatment, and flame treatment. The surface morphology and chemical composition of the metal adherends were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy and the bond strengths of the single-lap joints composed of aluminum and stainless steel adherends were measured with respect to hybrid surface treatment conditions. From the experiments, an effective hybrid surface treatment condition was suggested for metal surfaces with super-hydrophilic characteristics. Also, the failure mode of adhesive metal joints was evaluated by photo-surface analysis method.     

Effects of thermoplastic elastomer on the morphology and mechanical properties of glass fiber‐reinforced polycarbonate/acrylonitrile–butadiene–styrene

This article investigated the influence of thermoplastic elastomer like acrylonitrile–butadiene–styrene (ABS) high rubber powder (HRP), and ethylene methylacrylate (EMA) on the mechanical performances, flow ability, and morphology of glass fiber‐reinforced polycarbonate (PC)/ABS blends. Blending was carried out through a twin‐screw extruder, and all testing specimens were shaped by an injection molding machine. Experimental results showed that the toughening effect of EMA was more obvious than HRP due to fracture mechanism like crazing, shear yielding occurred in corporation with EMA. About 15 wt% glass‐fiber (GF) reinforcement and 6 wt% EMA toughening can get a balanced behavior among strength, stiffness, and toughness for superior performance of the polymer. POLYM. ENG. SCI., 59:E144–E151, 2019. © 2018 Society of Plastics Engineers     

3D打印用ABS丝材性能研究

以丙烯腈–丁二烯–苯乙烯塑料(ABS)为基体,分别以碳酸钙、短切玻璃纤维(GF)和色母粒为改性填料,通过挤出成型制备改性ABS丝材,然后采用3D打印技术中的熔融沉积成型(FDM)技术,通过FDM型3D打印机打印测试试样,对其力学性能及收缩率展开研究。研究结果表明,碳酸钙填料的加入使得ABS 3D打印试样的拉伸强度降低,用量为2份的短切GF可略微提高试样的拉伸强度,但随着GF含量的增加拉伸强度下降;当打印速度不高于50 mm/s时,相比于橘黄色母粒,蓝色母粒可提高试样的拉伸强度;改性ABS试样的拉伸性能随着打印速度的增加呈现两种不同的变化趋势,这可能由材料流动性能的差异所引起;随碳酸钙或GF用量增加,试样的收缩率逐渐降低,其中GF改性ABS试样收缩率的降低幅度更大,相比于橘黄色母粒,蓝色母粒的加入能够更有效地降低ABS试样的收缩率。     

Analysis of mold insert fabrication for the processing of microfluidic chip

The microfluidic chip has been used as an example to discuss different mold insert materials by micro hot‐embossing molding. For the mold insert, this study uses the SU‐8 photoresist to coat on the silicon wafer, then uses UV light to expose the pattern on the surface of SU‐8 photoresist, and coat the seed layer on the SU‐8 structure using thermal evaporation. The micro electroforming technology has been combined to fabricate the mold inserts (Ni, Ni‐Co) followed by replicating the microstructure from the metal mold insert by micro‐hot embossing molding. Different processing parameters (Embossing temperature, embossing pressure, embossing time, and demolding temperature) for the properties of COP film of microfluidic chip have been discussed. The results show that the most important parameter is the embossing temperature for replication properties of molded microfluidic chip. The demolding temperature is the most important parameter for surface roughness of the molded microfluidic chip. The Ni‐Co mold insert is the most suitable mold material for molded microfluidic chip by microhot embossing molding. The bonding temperature is the most important factor for the bonding strength of sealed microfluidic chip by tensile bonding test. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Effect of surface modifiers and surface modification methods on properties of acrylonitrile–butadiene–styrene/poly(methyl methacrylate)/nano‐calcium carbonate composites

Nano‐calcium carbonate (nano‐CaCO₃) was used in this article to fill acrylonitrile–butadiene–styrene (ABS)/poly(methyl methacrylate) (PMMA), which is often used in rapid heat cycle molding process (RHCM). To achieve better adhesion between nano‐CaCO₃ and ABS/PMMA, nano‐CaCO₃ particles were modified by using titanate coupling agent, aluminum–titanium compound coupling agent, and stearic acid. Dry and solution methods were both utilized in the surface modification process. ABS/PMMA/nano‐CaCO₃ composites were prepared in a corotating twin screw extruder. Influence of surface modifiers and surface modification methods on mechanical and flow properties of composites was analyzed. The results showed that collaborative use of aluminum–titanium compound coupling agent and stearic acid for nano‐CaCO₃ surface modification is optimal in ABS/PMMA/nano‐CaCO₃ composites. Coupling agent can increase the melt flow index (MFI) and tensile yield strength of ABS/PMMA/nano‐CaCO₃ composites. The Izod impact strength of composites increases with the addition of titanate coupling agent up to 1 wt %, thereafter the Izod impact strength shows a decrease. The interfacial adhesion between nano‐CaCO₃ and ABS/PMMA is stronger by using solution method. But the dispersion uniformity of nano‐CaCO₃ modified by solution method is worse. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013