基于翘曲变形的薄壁塑件成型工艺优化

基于Moldflow软件,对PC、ABS和PC+ABS三种材料薄壁塑件——键盘后盖的翘曲变形进行了数值模拟。按照影响翘曲变形的工艺参数设计了正交模拟试验方案,并完成了翘曲变形的正交模拟试验。据正交模拟实验结果、用极差分析法分析了各工艺参数对翘曲变形的影响程度,得到了最佳工艺参数组合。为类似薄壁塑件的注射成型提供理论和方法指导。     

ABS/PC共混合金制备及性能研究

制备了丙烯腈 丁二烯 苯乙烯共聚物 (ABS)接枝甲基丙烯酸甲酯 (MMA)。在ABS/PC共混中接枝共聚物作为相容剂使用。考察MMA接枝度与MMA用量、引发剂用量及热处理的关系。测定了共混合金的流动性能、玻璃化转变温度、抗冲性能和热变形温度 ,并与ABS、PC及无相容剂的ABS/PC进行比较     

Polycarbonate and co-continuous polycarbonate/ABS blends: influence of notch radius

The influence of notch tip radius in the range of 1-0.002 mm was studied on polycarbonate (PC) and co-continuous PC/acrylonitrile-butadiene-styrene (ABS). Co-continuous PC/ABS blend was obtained by mixing PC and ABS containing 15% polybutadiene (PB) in a twin screw extruder. PC and PC/ABS specimens were injection moulded into test bars. A notch was milled-in, with notch tip radius of 1, 0.5, 0.25 and 0.1 mm. Very sharp notches with a radius of 0.015-0.002 mm were obtained with an Excimer LAZER. The specimens were tested by single edge notch tensile tests at 1 m/s (apparent strain rate 28.5 s⁻¹) and at different temperatures (−60 to 130 °C). Initiation and propagation phases of the fracture process were monitored and the brittle-ductile transition temperature (T_bd) determined. It appeared that the amount of deformation in the initiation phase of fracture was extremely sensitive to notch tip radius. Temperature measurements of the deformation zone showed that the size of the deformation zone decreased with decreasing notch radius. The T_bd of PC increased rapidly with decreasing notch radius, until the glass transition temperature was approached. Remarkably, for PC the notch sensitivity was strongest around the standard notch tip radius of 0.25 mm. This means that a small deviation of this standard notch leads to large deviations in the results. The PC/ABS blend was much less sensitive to notch tip radius and the T_bd was almost constant. Thus the sensitivity of PC to sharp defects can be neutralised by adding ABS.     

Increasing recyclability of PC,ABS and PMMA: Morphology and fracture behavior of binary and ternary blends

Binary and ternary blends of PC, ABS, and PMMA were studied. The blends were produced from original and recycled materials by melt mixing in a wide range of compositions. Instrumented Charpy impact testing, tensile testing, rheology investigations, and electron microscopy were carried out to determine the relationship between the deformation and fracture behavior, blend composition, morphology, and processing parameters. Resistance against unstable crack propagation was evaluated using the concepts of J‐integral and crack‐tip‐opening displacement (CTOD). The transition from ductile elastic‐plastic to brittle‐linear elastic fracture behavior was observed in the case of PC/ABS/PMMA blend at 10% of PMMA. Reprocessing had only a slight influence on the deformation and fracture behavior of the recycled blends. The blends produced from recycled materials proved to be competitive with the original pure materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Effects of blend composition on the morphologies and physical properties of polycarbonate/acrylonitrile-butadiene-styrene blends

The morphologies and physical properties of twin-screw-extruded polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends with various blend ratios are studied. The needle-like co-continuous phase in PC-rich blends changes to the sea-island phase for blend ratios of more than 50 wt% ABS. While pure PC exhibits an almost-Newtonian flow behavior, PC/ABS blends exhibit the interesting rheological transition. The viscosities of the ABS-rich blends at low shear rates are almost equal to those of the pure ABS polymer. The yield stress for the PC/ABS blend ratio of 3:7 is the highest in composition. At the frequency of 10 rad/s, the PC-rich blends exhibit highly viscous properties, whereas the ABS-rich blends present highly elastic properties as the temperature increases. Moreover, the ABS polymer in the PC/ABS polymer blend induces significant change at the fracture surface of PC, transitioning from brittle to ductile nature.     

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.     

Compatibility enhancement of ABS/polycarbonate blends

The effects of blend composition, melt viscosity of poly(acrylonitrile-butadiene-styrene) (ABS), and compatibilizing effect of poly(methyl methacrylate) (PMMA) on mechanical properties of ABS/polycarbonate (PC) blends at ABS-rich compositions were studied. As the content of PC was increased, impact strength and Vicat softening temperature (VST) were increased. As the melt viscosity of ABS was increased near to that of PC, finer distribution of dispersed PC phase and consequent enhanced impact strength and VST were observed. The compatibilizing effect of PMMA can be ascer-tained from the enhanced properties of ¼-inch notch impact strength, VST, tensilestrength, and the morphology observed by a scanning electron microscope. The improved adhesion of the ABS/PC interface by PMMA changed the fracture mechanism and reduced the notch sensitivity of blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 533–542, 1998     

基于MPI和灰色关联异型出风罩注塑参数优化

针对某异型出风罩注塑成型工艺,以聚碳酸酯/丙烯腈-丁二烯-苯乙烯共聚物(PC/ABS)工程塑料合金为填料,运用Moldflow软件对其注塑过程进行模流分析,通过田口实验设计研究了熔体温度、保压时间、保压压力、注射时间和模具温度对塑件收缩率和翘曲变形量的影响,得到它们对塑件收缩率的影响次序为:保压时间>熔体温度>保压压力>注射时间>模具温度,对翘曲变形量的影响次序为:保压压力>注射时间>熔体温度>保压时间>模具温度。基于灰色关联分析,获得了最优组合工艺参数,即:熔体温度280℃、模具温度为65℃、注塑时间2.1 s、保压时间11 s、保压压力21 MPa。优化后的仿真结果表明,塑件的体积收缩率为6.523%、翘曲变形量为0.80 mm,比灰色关联次序中位组合的样本数据分别降低6.9%和15.8%,并获得最大注射压力为20.34 MPa、最大锁模力为3.25×10^5 N,为后期模具的设计和注塑参数设定提供了有力的参考,缩短了模具开发周期。     

A comparison of the thermoformability of a PPE/PP blend with thermoformable ABS. Part I: Small deformation methods

Different factors important in ascertaining the thermoformability of polymeric materials are identified and defined. These include resistance to sag, ease of flow, mold replication, deep draw capability, sensitivity to thermoforming temperature and speed, uniformity of thickness distribution, and post‐forming shrinkage and dimensional stability. Methods to study these properties can be classified into small deformation and large deformation methods. The small deformation methods, which are the subject of this paper, include dynamic temperature sweep tests, dynamic frequency sweep tests, stress relaxation time, and creep recovery tests. These tests were used to compare the thermoformabilities of a blend of polyphenylene ether (PPE) and polypropylene (PP) and thermoformable acrylonitrile butadiene styrene (ABS) resin. The dynamic temperature and frequency tests showed that the PPE/PP blend generally has a better viscoelastic balance than ABS implying a better balance between resistance to sag and ease of flow. Creep recovery tests suggested that the PPE/PP blend may offer better mold replication during thermoforming. Studies based on the stress relaxation time showed a lower residual stress build‐up in thermoformed PPE/PP blend than ABS implying better dimensional stability and a higher in‐service temperature window for the thermoformed PPE/PP blend than ABS. POLYM. ENG. SCI., 45:1369–1376, 2005. © 2005 Society of Plastics Engineers     

Reprocessing polycarbonate/acrylonitrile-butadiene-styrene blends: Influence on physical properties

A commercial polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend was reprocessed by injection molding to study the influence of reprocessing on the physical properties of the product. The modulus of elasticity and the yield stress are unaffected by reprocessing, whereas the break properties and the impact strength decrease. The effects observed are compared with those found in PC and ABS. The type of reactions taking place during reprocessing and the change of blend morphology are also discussed.     

Shear deformation and fracture behaviour of polycarbonate–acrylonitrile/butadiene/styrene blend at high strain rates

Abstract

The purpose of the present research was to study systematically the shear deformation and fracture behaviour of a polycarbonate–acrylonitrile/ butadiene/styrene (PC–ABS) blend subjected to high shear strain at high strain rate, using a torsional, split Hopkinson bar. Thin walled tube specimens were deformed at room temperature under strain rates ranging from 10² to 5 × 10³ s^-1. The effects of strain rate on shear flow response, strain rate sensitivity, thermal activation volume, and shear modulus were evaluated. Damage initiation, propagation, and fracture mechanisms were studied by scanning electron microscopy. Correlations between dynamic flow response and observed fracture features are characterised and discussed in terms of loading conditions. The data indicate that the dynamic shear response of the PC–ABS blend is greatly affected by applied strain rate. An increase in shear stress and shear modulus with strain rate was observed. Fracture strains decrease with increased loading rate. Tearing and shear fracture are the major fracture mechanisms and depend quite strongly on the strain rate.     

Boiling water aging of polycarbonate and polycarbonate/acrylonitrile–butadiene–styrene resin and polycarbonate/low‐density polyester blends

The effects of boiling water on the mechanical and thermal properties and morphologies of polycarbonate (PC), PC/acrylonitrile–butadiene–styrene resin (PC/ABS), and PC/low‐density polyester (PC/LDPE) blends (compositions of PC/ABS and PC/LDPE blends were 80/20) were studied. PC and the PC/ABS blend had a transition from ductile to brittle materials after boiling water aging. The PC/LDPE blend was more resistant to boiling water aging than PC and the PC/ABS blend. The thermal properties of glass‐transition temperature (T_g) and melting temperature (T_m) in PC and the blends were measured by DSC. The T_g of PC and PC in the PC/ABS and PC/LDPE blends decreased after aging. The T_g of the ABS component in the PC/ABS blend did not change after aging. The supersaturated water in PC clustered around impurities or air bubbles leading to the formation of microcracks, which was the primary reason for the ductile–brittle transition in PC, and the microcracks could not recover after PC was treated at 160°C for 6 h. The PC/ABS blend showed slightly higher resistance to boiling water than did PC. The highest resistance to boiling water of the PC/LDPE blend may be attributed to its special structural morphology. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 589–595, 2003     

Thermal aging of bisphenol-A polycarbonate/acrylonitrile–butadiene–styrene blends

Thermal aging of immiscible bisphenol-A polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) blends containing 25, 60, and 75% PC and the PC and ABS blend components have been studied. Changes in Izod impact properties and dynamic mechanical spectra are reported following aging at 90, 110, and 130°C for times up to 1500 h. PC/ABS blends containing 60 and 75% PC were found to retain high impact performance following aging at elevated temperatures, compared to the PC blend component. Dynamic mechanical spectroscopy is an effective probe for investigating the structure–property changes occurring and the mechanisms of aging. For PC and ABS, the changes were mainly due to physical aging of the amorphous polymers when aged below the glass-transition temperature. For the PC/ABS blends, oxidative degradation additionally contributes to loss of toughness. Although structure–property changes are related to the behavior of the blend components, additional factors of potential importance for multiphase polymer–polymer systems have been identified, including a redistribution of stabilizers during the blend manufacture. © 1995 John Wiley & Sons, Inc.     

Morphology–property relationships in ABS/PET blends. II. Influence of processing conditions on structure and properties

The effect of processing temperature on the low-speed tensile and high-speed impact properties of novel ABS/PET blends was investigated. In agreement with the conclusions from related studies of ABS/PC blends, it appears that catalytic impurities in the ABS accentuate the propensity of PET for chain scission. Due to the cocontinuous structure of the blend, the hydrolytic or thermomechanical degradation of the PET results in a dramatic loss in mechanical properties which can be explained by the entanglement theory for fracture and the Orowan brittle–ductile hypothesis. © 1996 John Wiley & Sons, Inc.     

Analysis of crack phenomenon for injection‐molded screw using moldflow simulation

The screw for ice water filter machine was injection molded with acrylonitrile–butadiene–styrene (ABS)/polycarbonate (PC) [ABS/PC] alloy resin and its crack phenomenon after mechanical stress was analyzed by commercial Moldflow software. The cracked morphology and tensile properties of ABS/PC have been studied by scanning electron microscopy (SEM) and universal test machine (UTM). The injection pressure and the residual stress has been compared with two injection molding conditions as actual manufacturing and reduced injection flow rate. This analysis has found that residual stress is higher at actual manufacturing condition. SEM study reveals that in the micrographs taken on the surface of cracked sample ABS rubber domains tend to extremely align in the direction of mold flow. The combined data suggest that the majority of the crack comes from residual stress in final part originated from higher injection pressure during injection‐molding process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structure and properties of polyblends of a thermotropic liquid crystalline polymer with an alloy of polyamide-6 and ABS

The relationship between the microstructure and corresponding mechanical properties developed during injection molding of blends containing a liquid crystalline polymer (LCP) as the minor component and an engineering polymer system has been studied. A wholly aromatic copolyester LCP (Vectra A950) was melt blended at different compositions with a thermoplastic matrix consisting of a commercial compatibilized blend of polyamide-6 and ABS (Triax 1180). These blends were prepared under two different sets of injection molding conditions. In the first case, a higher melt temperature, higher barrel temperature, lower injection pressure, lower mold temperature, and shorter residence time in the mold were used during injection molding, as compared with the second case. The mechanical properties of the blends were superior to those of the base polymer. In the second case, the resulting injection-molded specimens had a distinct skin–core morphology where elongated fibrils of LCP constituted the skin layer. The mechanical properties of the blends processed under the second set of processing conditions were superior to those of the first, though the trends in both cases were the same. To study the effects of process variables the 15% LCP blend and the second set of processing conditions were taken as the base. Samples were injection-molded by varying one parameter at a time. It was seen that the properties of the blend were increased by maintaining a lower barrel temperature, greater injection pressure, lower injection speed, higher mold temperature, and a greater residence time in the heated mold. Thus it was found that the processing conditions played a vital role in determining the mechanical properties and morphology of the polyblends. © 1996 John Wiley & Sons, Inc.     

Influence of Recycled ABS Added to Virgin Polymers on the Physical,Mechanical Properties and Molding Characteristics

Reuse of recycled polymers is steadily increasing. In this study, two different ABS virgin materials are considered. Then, blends of varying proportions of ABS recycled resins (0–50%), obtained from the gate and runner materials of products, was added to virgin resin to investigate the effect of various compositions of virgin ABS and recycled polymers on the physical and mechanical properties of the final blend. Three different rib and closure organization of boss of the reinforcement structures were designed and injection molded under blends of varying proportions of the ABS recycled resins to do the torsion test by Air-Torsion tools. In addition, molding characteristics were also examined. The results show that there is no obvious effect of recycled ABS percentage (by weight) on the tensile strength, elongation at yield, flexural strength, flexural modulus, and impact strength. However, the torsion strength for rib and closure organization of boss of the reinforcement structures decrease with increasing recycled ABS weight percentage. On the other hand, hardness, glass transition temperature, and melting flow index of recycled ABS increase with as the percentage (by weight) of recycled material increase. The impact strength was found to vary with the recycled ABS loading. The injection pressure decreases with increasing the content of recycled resin under some specified molding conditions.     

The effect of recycling number on the mechanical,chemical, thermal,and rheological properties of PBT/PC/ABS ternary blends: With and without glass‐fiber

The recycling possibilities of poly(butylene terephthalate)/polycarbonate/acrylonitrile–butadiene–styrene (PBT/PC/ABS) ternary blend with and without glass‐fiber content were investigated using repeated injection molding process. In this study, PBT/PC/ABS ternary blends were reprocessed at five times and the results were presented after each recycling process. The recycling possibility of PBT/PC/ABS ternary blend was evaluated by measuring the mechanical, chemical, thermal, and rheological properties. Mechanical properties were determined by the tensile strength, yield strength, strain at break, elastic modulus, impact strength, flexural strength, and flexural modulus. Chemical and thermal properties were evaluated by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and scanning electron microscopy. Rheological properties of the ternary blends were studied by melt flow index measurement. From the results, it was found that mechanical properties of recycled composites were better than virgin PBT/PC/ABS ternary blends. POLYM. COMPOS., 35:2074–2084, 2014. © 2014 Society of Plastics Engineers     

ABS/PC回收再造过程中形成孔洞规律的研究

以初级形态的ABS/PC树脂为原料模拟进行了熔融，加压，挤出造粒等回收再造的过程，并对再造粒进行了ES-EM表征和熔体质量流动速率的测定。研究了ABS/PC共混树脂回收再造后，粒子断面产生孔洞的规律。结果表明；ABS/PC回收再造后粒子断面出现的孔洞系ABS/PC中PC在高温条件下水解所致，且回收再造的次数越多，树脂的含水量越大，则孔洞数量越多，尺寸越大。这对出入境检验检疫部门和海关的执法检验及企业的日常检修人有实际应用价值。     

Co-continuous polycarbonate/ABS blends

Co-continuous PC/ABS (50/50) blends were studied with a variable polybutadiene (PB) content (0-40%) in ABS. Polycarbonate (PC), styrene-acrylonitrile (SAN) and PB were blended in two steps using a twin screw extruder. Rectangular bars were injection moulded and notched Izod impact tested at different temperatures and in single edge notch tensile tests at 1 m/s and different temperatures. Co-continuous PC/ABS gave a brittle-to-ductile transition temperature lower than expected based on notched Izod results for dispersed ABS in PC. The brittle-to-ductile transition temperature, in the co-continuous PC/ABS blends, decreased with increasing rubber content in SAN. The fracture energies showed an optimum at 15% PB in SAN while at the same time a delamination was seen on the ductile fracture surface, due to failure of the PC/SAN interface. Delamination disappeared when the rubber content in SAN or the temperature was increased. Specimens containing a welding were injection moulded to study the influence of rubber and AN content in the SAN on the interface. Weldline strength of the blends was very poor compared to PC, but improved with increasing rubber content in SAN.