SPE Library

Temperature is one of the most important processing parameters in injection molding which has effects on products quality and production efficiency. The relatively assistant heating and cooling technologies to adjust mold and resin temperature during the injection molding processing were discussed, including heated water, electric heater, induction heating and chill water. Firstly, the heating/cooling effects on the uniformity of mold temperature field and the time consumption to obtain the ideal processing temperature were considered by experiments. Then the appearance quality of molded parts (surface roughness) produced by the heating/cooling technologies were measured. The residual stress distribution of transparent PC parts made by different cooling rate was examined by photoelastic instruments. Compared with traditional processing, it is found that microcellular injection molded specimens average surface roughness was reduced from 26?m to minimum 5.1?m when mold temperature above 18? oC? From a series of multicolored band or fringe pattern, it shows that when mold temperature increase 20 oC???he stress strip reduced from 6 to 2, which meant less residual stress.

Solid state shear pulverization is a novel technology in polymer processing for production of new polymeric materials. By implementation of this technology various processes such as polymer recycling compounding and improving of mechanical-chemical properties of polymers can be enhanced. This is a continuous and one-stage process with low energy consumption. During this process polymers are subject to high pressure and shear forces. In this paper this technology and its applications to polymer processing is perused. At the end recycling of PET wastes by this technology is presented that have higher efficiency in comparison with existing methods.

The synthesis and physical properties of soft plasticizer-free thermoplastic polyurethanes (TPUs ) exhibiting durometers below 70A on the Shore scale have been investigated. The TPUs have been further characterized in terms of their thermal and tensile characteristics set and tear properties as well as density. By employing hydrocarbon polyols along with suitable chain extenders aromatic TPU with specific gravity less than 1.0 that exhibit acceptable physical properties and exhibit low compression set characteristics have been prepared. Furthermore these TPUs are hydrophobic an unusual characteristic for a TPU which suggests that they could be useful for applications where TPUs would not normally be considered e.g. water barriers.

The synthesis and physical properties of soft plasticizer-free thermoplastic polyurethanes (TPUs ) exhibiting durometers below 70A on the Shore scale have been investigated. The TPUs have been further characterized in terms of their thermal and tensile characteristics, set and tear properties as well as density. By employing hydrocarbon polyols along with suitable chain extenders, aromatic TPU with specific gravity less than 1.0, that exhibit acceptable physical properties and exhibit low compression set characteristics, have been prepared. Furthermore, these TPUs are hydrophobic, an unusual characteristic for a TPU, which suggests that they could be useful for applications where TPUs would not normally be considered, e.g., water barriers.

We present a Multi-sample Micro-capillary Rheometer (MMR) which is capable of measurements over a broad range of temperatures viscosities and shear rates. The instrument is simple as the flow is generated by external gas pressure and the shear rate is measured optically. We test the MMR against two National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) three low viscosity standards and one commercial polymer (Polydimethlysiloxane Polyisobutylene solution Oils and Polystyrene) and report a high level of accuracy and precision. This instrument will be particularly useful as a combinatorial method and in cases of limited material quantity (typical sample size
20 ?¬L). The dynamic range of the instrument is eightorders of magnitude in viscosity and four orders of magnitude in shear rate.

Cyclic olefin copolymers (COC) can provide film producers and packaging converters with an opportunity to create thermoforming films. COCs are amorphous thermoplastics with excellent moisture barrier high temperature stability and stiffness. Mono- and multi-layer examples of LLDPE-based forming films compared against commercially available products clearly demonstrate how well the addition of COC improves physical properties thermoforming and packaging performance. COC improves material distribution of LLDPE formed trays. These improvements enable the formed tray to withstand higher crushing force. Enhanced performance permits possibility of down gauging.

Chemical resistance of resins determines the lifetime of plastic materials. Chemically stable resins with ester groups undergo the hydrolysis in acidic environment.This hydrolysis is catalyzed by hydronium ions.The Hammett acidity function determines the concentration of hydronium ions in concentrated acids and their mixtures.This function can be used for material evaluations in laboratory testing and specific industrial environments.We used this approach to evaluate the chemical resistance of Dion 9100 (epoxyvinylester based resin) and Polilate 250 (unsaturated isophtalicpolyester based resin).

The principles of materials compatibility for joining of plastics using multi-component injection molding have been investigated. In order to expand compatibility matrices the influence of processing transient and pretreatment parameters on the bonding strength has been identified. The Experimental approach has included the determination of the influences of in-line-plasmapretreatment melt temperature on the contact zone and the surface contamination. Electron spectroscopy surface tension electron microscopy and IR-temperaturemeasurements have been used to analyze the contact surface.

2D numerical simulations of the interface distribution and flow birefringence for combinations of PS PC and PMMA in sequential co-injection molding of a centergated disk were performed. A hybrid control volume/finite element/finite different method with modeling based on nonlinear viscoelastic constitutive equation and stressoptical rule was used. Free quenching was performed and thermal birefringence was measured. Interface distribution and birefringence in moldings were measured. The thermal birefringence is added to the flow birefringence to obtain the birefringence. The simulation results for the interface distribution and birefringence qualitatively match with experimental results.

2D numerical simulations of the interface distributionand flow birefringence for combinations of PS, PC andPMMA in sequential co-injection molding of a centergateddisk were performed. A hybrid control volume/finiteelement/finite different method with modeling based onnonlinear viscoelastic constitutive equation and stressopticalrule was used. Free quenching was performed andthermal birefringence was measured. Interface distributionand birefringence in moldings were measured. Thethermal birefringence is added to the flow birefringence toobtain the birefringence. The simulation results for theinterface distribution and birefringence qualitatively matchwith experimental results.

There is an increasing demand for light weight low system/part cost high fuel efficiency recyclability low manufacturing cost and freedom of parts consolidation for under the hood parts.This presentation will discuss state of the art for several key applications such as HVAC components radiator components fan-shroud assemblies/modules air intake manifolds engine (or ƒ??beautyƒ?) covers rocker panels and other multi-functional assemblies etc.Plastics have made significant inroads in valve covers and air-intake manifolds. In valve covers (also called rocker or cam covers) thermoplastics are replacing thermosets. Advances in thermoset materials will also be discussed. The reason for using other technologies other than conventional injection molding such as thermoforming blow molding water/gas injection molding etc. will be discussed for above mentioned applications. For example future air-intake manifolds may utilize laser welding to join two shell halves with less potential damage to sensitive electronics than with vibration welding.To reduce part weight technologies like thin wall molding microcellular foaming and nanocomposite molding will be discussed. There is a need for high flow materials with high temperature capabilities.Opportunities for several material families such as polyamide Polyolefinic materials PPS PPA etc are discussed. Integration need such as fan/shroud with partial or full front end module instrument module with HVAC integration cam cover with gasket and oil/air separator into one lower-cost module; air-intake manifold and rocker panel into a single multi-functional assembly. etc; will be briefly discussed.

A pressure driven micro-rheometer was developed. It uses 80 mg of material to measure the viscosity of polymer melts at shear rates ranging from ten to several thousands s-1. The maximum shear rate can be extended to several 104 s-1 with 200 mg of sample. The main part of the rheometer consists of two sample reservoirs connected through a slit channel (H = 0.1 mm W = 1 mm L=5 mm) and two pistons. The double piston arrangement enables using the same material repeatedly by the reciprocating flow of the polymer melt from one reservoir to the other.In addition by using a very thin slit channel the viscosity of polymer melts can be measured over a wide range of shear rates whilst using only a small quantity of material.Measured viscosity was in good agreement with that by a capillary rheometer and it was found that slip is negligible in the slit die used in this study.

This study investigated the influence of montmorillonite (MMT) content on the mechanical/thermal properties of microcellular injection molded Polylactide (PLA)/clay nanocomposites. Carbondioxide (CO2) was the blowing agent. The PLA/MMTnanocomposites were prepared by twin screw extrusion.The results showed that as MMT content is increased tensile strength impact strength and cell density decrease.This is caused by the speed degradation of PLA due to the addition of MMT. MMT decreases the crystallization temperature but increases the decomposition temperature of the nanocomposites. The XRD results showed that the layer spacing of the clay increases as MMT content increases. TEM pictures showed that the MMT is well dispersed within the PLA matrix.

An organically modified montmorillonite was compounded with polystyrene (PS) in a twin-screw extruder. The organoclay polystyrene nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclay content on the mechanical and thermal properties was investigated. The results showed that when the MMT content was 1 wt% the nanocomposites have maximum tensile strength wear resistance and cell density. Moreover the addition of organoclay increases the glass transition and decomposition temperature of the nanocomposites. The XRD results showed that the layer spacing of the nanocomposites decreases by comparison with the organoclay. TEM pictures showed that MMT is well dispersed within the PS matrix.

Polymer chain orientation achieved through the die drawing process has been shown to significantly improve the mechanical properties of both filled and unfilled polymer products1. However inclusion of filler particles tends to result in localised cavitation and subsequent propagation which reduces stiffness enhancements. By tailoring production parameters such as rate temperature and geometry it is possible to control both the modulus and density of the final product to given specifications. Within this paper we demonstrate the effects of die angle and temperature on the final sample properties of a civil engineering product and their optimisation to manufacture a low density high stiffness component.

Polymer chain orientation achieved through the die drawing process has been shown to significantly improve the mechanical properties of both filled and unfilled polymer products. However, inclusion of filler particles tends to result in localised cavitation and subsequent propagation, which reduces stiffness enhancements. By tailoring production parameters such as rate, temperature and geometry it is possible to control both the modulus and density of the final product to given specifications. Within this paper we demonstrate the effects of die angle and temperature on the final sample properties of a civil engineering product and their optimisation to manufacture a low density high stiffness component.

Traditionally mold design has been taught on a theoretical basis where student’s designs never leave the drawing board. Today’s computer aided manufacturing techniques allow for hands-on design projects. A junior level mold design engineering class was revised to include an intensive art-to-part project. Given constraints students designed new plastic parts manufactured the tooling using CAM software and CNC machining and injection molded prototype parts. In addition to mold design students learned machine tool practices and the difficulties associated with commissioning new tools. The project required considerable initial investment but was met with an overwhelmingly positive response.

Traditionally mold design has been taught on a theoretical basis where studentƒ??s designs never leave the drawing board. Todayƒ??s computer aided manufacturing techniques allow for hands-on design projects. A junior level mold design engineering class was revised to include an intensive art-to-part project. Given constraints, students designed new plastic parts, manufactured the tooling using CAM software and CNC machining, and injection molded prototype parts. In addition to mold design, students learned machine tool practices and the difficulties associated with commissioning new tools. The project required considerable initial investment, but was met with an overwhelmingly positive response.

Combining molecular orientation of polymer chains with short glass fibre reinforcement has been shown to significantly improve material stiffness in the direction of orientation1. Replacement of the stiff glass fibres with inorganic fillers also has the capability of improving mechanical performance of oriented composites but at a reduced production cost. Orientation is achieved via a batch die drawing process 5 to 20 oC below the melt temperature of the polypropylene inorganic composite material. This experimental investigation has now been extended to consider cavitation around particulates within the composite material during the die drawing process using macroscopic and microscopic finite element models validated via image analysis and density measurements of actual drawn components. Within this paper we demonstrate the modelling route to achieve micro-scale predictions of cavitation based on a macroscopic analysis of the complete component through a technique known as submodelling.

Combining molecular orientation of polymer chains with short glass fibre reinforcement has been shown to significantly improve material stiffness in the direction of orientation. Replacement of the stiff glass fibres with inorganic fillers also has the capability of improving mechanical performance of oriented composites but at a reduced production cost. Orientation is achieved via a batch die drawing process 5 to 20 oC below the melt temperature of the polypropylene inorganic composite material. This experimental investigation has now been extended to consider cavitation around particulates within the composite material during the die drawing process using macroscopic and microscopic finite element models validated via image analysis and density measurements of actual drawn components. Within this paper we demonstrate the modelling route to achieve micro-scale predictions of cavitation based on a macroscopic analysis of the complete component through a technique known as submodelling.