The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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The deformation and fracture behaviour of polyamide-6/silicate nanocomposites are studied. With increasing clay content the modulus increases much more substantially than can be achieved with micron-sized clay particles, but the fracture toughness drops significantly. The micromechanisms of fracture are relatable to the microstructure of these materials. The matrix is capable of a surprising amount of shear plasticity. Rubber modification is effective in producing more crack tip damage which increases the toughness of these composites.
Ali A. Yousefi, Mosto Bousmina, Abdellatif Ait-Kadi, May 1999
Polypropylene (PP) was functionalized with maleic anhydride (MAH) and diethyl maleate (DEM) in a twin-screw extruder. The functionalized PPs were mixed with a 80/20 wt./wt.% blends of polypropylene and ethylene-vinyl alcohol copolymer (EVOH) and the extruded films were stretched at the exit of the flat die. The effect of the functionalized PPs and stretching on PP/EVOH blend were investigated. Morphological analysis along with mechanical and thermomechanical analysis showed that PP-g-DEM is a good candidate for tailoring materials with enhanced barrier properties.
This paper will review the use of melt-processible rubber (MPR) in overmolding and co-extrusion with various rigid plastic substrates. Looking to improve product quality and develop new applications, plastics engineers are turning to MPR technology to cost-effectively add the high performance properties and warm, soft feel of rubber to their products. MPR exhibits superior resistance to weather, oils, chemicals, gasoline, and UV light, and is processed on conventional plastics equipment, which provides potential cost savings.
A. Derdouri, A. Garcia-Réjon, K.T. Nguyen, Y. Simard, Kurt A. Koppi, Brent A. Salamon, May 1999
The effect of the core/skin ratio on the overall flow behaviour in the co-injection molding process was studied. A 7.6x16.4x0.7 cm3 rectangular plaque was moulded using a 150-ton Engel co-injection machine. ABS was used both for the skin and core material and PC were used only as the skin material. For visualization purposes, a black pigment was added to the core material. The results are discussed in terms of the relative viscosity, injection speed, melt and mould temperatures.
S.-S.L. Wen, C.-K. Jen, K.T. Nguyen, A. Derdouri, Y. Simard, May 1999
Ultrasonic pulse-echo techniques were used to monitor the entire injection molding process including the flow front advancement, the end of filling, the packing phase, the solidification and the detachment of the part from the mold. Compared to conventional pressure and temperature sensors, ultrasonic sensors are non-intrusive, have very fast response and can provide unique capabilities such as monitoring of filling and solidification, and detection of part/mold detachment from both sides of the cavity.
Roller pull-off experiments have been performed to investigate the rod strength with and without blowing agent. Low density polyethylene was melted to mix with physical blowing agent, or to liberate inert gas by decomposing chemical agent to form a homogeneous melt in the extruder. The extrudate exit a capillary die and went through a driven nip roll for force measurement at a given speed. Extensional viscosity was calculated from the pulling force and roller speed. It appears that plasticization and foaming are important factors in the stretched strength analysis.
Foam extrusion experiments were performed to study the effects of surrounding temperature variation on cell structure. Linear low density polyethylene was used with endothermic chemical blowing agent on a single screw extruder to exit from a capillary die into environments with different temperatures. Cell density, foam density, and cell morphology were investigated. The amount of chemical blowing agent and the surrounding conditions have to be viewed together to correlate with the cell density. Foam density appears to be related to gas escape from the surface during foaming.
The effect of lubricants, impact modifier, and process aid on the processing and physical properties of a rigid PVC compound have been modeled using a Central Composite designed experiment. Capillary rheology was used to evaluate the flow properties of the various formulations in the study. By modeling the rheological properties it is possible to simultaneously optimize flow, extruder conditions, and final part properties.
Kurt Hayden, Paul Engelmann, Robert Dealey, Michael Monfore, May 1999
The plastics industry is under increasing pressure to reduce the wall thickness of molded parts. Thin wall molding provides a host of concerns not present in standard molding applications. An analysis of the relationship between tool wear and wall thickness was conducted as part of the long-term copper alloy mold wear studies at Western Michigan University (WMU). This analysis suggests tool design for the proactive reduction of high shear erosive wear associated with thin wall molds.
In gas assisted injection moulding the melt front advancement has a considerable effect on the gas penetration. The evaluation of an appropriate melt filling is an important step to avoid instabilities in the process sequence. Taking a sample moulded part a procedure is presented that enables the part designer to evaluate required melt and gas injection points according to the gas injection technique. Using finite element simulations different calculations for the melt front advancement lead to the correct gate location in correspondence with the gas nozzle and the part geometry.
Cyanate ester resins were modified using thermoplastic and elastomeric materials to study their effect on properties and long term durability when used as high temperature matrices in glass fiber composites. Toughness improvements without significant sacrifices in flexural properties were only observed for the systems that did not phase separate. Conversely, the thermal properties of these materials were more seriously affected after exposure to a high temperature environment.
Mark Doyle, Albert Bernier, Karen Camille, David Kazmer, May 1999
Just-in-time business agreements have forced molders to become more flexible in the way they produce parts. One way to improve efficiency in the production of complete assemblies is to mold all of the components at once in a family tool. This paper examines the ability of Dynamic Feed Control to produce high quality parts in family tools with widely varying parts in regards to wall thickness and volume.
Patrice G. Godfroy, Michel A. Huneault, Pierre G. Lafleur, May 1999
Glycidyl methacrylate grafted polypropylene (PP-GMA) was used as a coupling agent in a PP/talc blend. Two coupling agents with GMA grafting levels of around 0.34 %wt. and different molecular weights were used. It was found that the use of PP-GMA at concentration between 1 and 10 %wt. increased the tensile strength and impact resistance of PP/talc composites. The performance of the PP-GMA was comparable to commercial PP-MAH modifiers. The chemical or physical effect of the coupling agent are discussed.
Weld lines are sometimes inevitable when processing large and complex parts by injection molding. In this paper, a design of experiments approach (Taguchi Method) was utilized to study the influence of seven processing variables (melt and mold temperatures, injection and hold pressures, cooling and holding times, and back pressure) on the weld line width and the tensile impact properties of injection molded dog-bone bars. The important processing variables affecting the weld line behavior are identified.
W. Zhou, A. Chudnovsky, C.P. Bosnyak, K. Sehanobish, May 1999
Characterization and comparative analysis of necking phenomena in HDPE under load (creep) and displacement (ramp) control conditions are reported. For creep tests a simple exponential dependence of delay time to necking on the applied stress is observed. The applied stress and strain rate dependence of yield stress for both creep and ramp tests are presented.
John D. Clay, Bhima Vijayendran, Jan Moon, May 1999
The gelling of soy protein-based PRF wood adhesives is studied. Soy protein isolate, in combination with phenol resorcinol formaldehyde (PRF) resins is useful in the finger joining of lumber. This unique technology has several advantages including an ability to bond green lumber, very rapid set at room temperature, excellent water resistance, and reduced formaldehyde emissions. The goal of this study is to quantify the effect of soy protein hydrolysis conditions and amine functionality on the gelling and ultimate modulus of soy-derived wood adhesives.
This paper describes the effects of talc and mica as fillers in rotationally moulded medium density polyethylene-MDPE. Adhesion between the filler and the matrix was enhanced using maleic anhydride modified polyethylene. Results show a clear increase of the modulus and in some cases an improvement in the tensile strength, but a decrease in the elongation and impact properties. Shrinkage of the moulded articles was reduced, and internal air temperature measurements show a reduction in the cycle time.
This paper describes the development of a computer simulation for the rotational moulding of plastics. Two separate aspects of the process - the kinematics of the mould rotation and the heat transfer to the plastic powder - are modelled separately and then combined into a complete simulation. The simulation is capable of reading CAD files of real rotomoulded components, and variables such as speeds, speed ratios, material bulk density, etc can be set by the user. The program will then predict and display the wall thickness distribution in the moulded article.
Blends of polyethylene (PE) with very low TLCP concentrations have viscosity ratios of 10-6 to 10-4, and viscosity reductions > 90% are observed. This viscosity reduction is generated by a number of mechanisms in sequence, wall slip being only one. The others are droplet coalescence, deformation and fibril formation, plus effects associated with the TLCP's ability to self-order and align when under shear, leading to a phase transition in the nematic-isotropic biphase. Intercomponent adhesion and interfacial tension also influence the droplet dynamics.
Filtration is required of nearly every flowing polymer process. Most processes utilize filter elements that must be removed periodically for replacement or cleaning. The gradual pressure buildup that accompanies filter blinding results in an unwanted temperature rise with consequent loss in dimensional control of the product and sometimes with a reduction in output. A continuous filter that would continuously replace itself or that would clean itself automatically has been sought by industry. This paper describes the original device of this sort and reveals how it operates.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.