SPE Library
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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Conference Proceedings
Fusion Mechanism in Rigid PVC
A classic approach for studying network effects in carbon black containing rubber was applied to PVC with stabilizer. This approach involves measuring the shear modulus with increasing strain. In carbon black containing rubber, the modulus drops dramatically at a critical strain level. This is known as the Payne effect" [1] and is associated with the break-up of the carbon black network. PVC that was fused to different levels in a bowl mixer shows exactly the same behavior and the drop point correlates very well with the fusion peak in the mixing bowl. The relationship between network effects and fusion in PVC will be discussed."
Syndiotactic Polypropylene Using Different Supported Metallocene Catalyst
Polymerizations of propylene were carried out with ?2C(Flu)(Cp)ZrCl2 catalyst supported on silica, sodic modernite (NaM) and ZSM-5. The molecular weight, molecular weight distribution, melting point and crystallinity of the obtained polymers and also catalytic activity were examined. The results report very high activities for the heterogeneous systems, specially with ZSM-5 as carrier. Higher melting point and crystallinity degree were presented in polypropylene synthesized with the catalyst supported on NaM.
Dimensional Stability of LDPE Foams: Modeling and Experiments
The thickness change of extruded LDPE foam to the blowing agent and air counter diffusion during the post-extrusion aging process is modeled. The blowing agent and air counter diffusion equations are coupled with the viscoelastic equations to model the foam volume shrinkage and recovery processes in a closed-cellular low-density LDPE foam. The variables studied include polymer elastic and viscous constants, foam sheet thickness, cell count and foam density. The mathematical model is also compared with experimental data.
Coaching and Mentoring: Change Management
In a global economy featuring mass customization, ubiquitous information, and extreme price and service competition, many companies have found it paramount to remain flexible. Flexible to answer customer needs and wants faster, better, cheaper. For many companies the required flexibility demands organizational change at a rapid rate. Organizational change, if not managed properly can cause serious internal and external performance issues. Coaching and mentoring can be used to manage, and even drive, change in your organization while building value and employee involvement in the change.
Failure Analysis Case Study - A Systems Solution
Failure analysis typically employs a series of appropriate tests that result in a conclusion about the cause or causes of a product failure. Often the problem involves an interaction between the plastic part and other components in the product or between the plastic part and application conditions. Identifying these interactions is an important part of developing a solution that resolves the problem without unduly increasing costs. This paper outlines a case study in which a proper analysis of the failure mode and knowledge of commercial alternatives led to multiple options for a solution.
What Position on the Viscosity Curve Is the Most Repeatable with Respect to End of Fill Cavity PSI
For many years, educators in the injection molding industry have suggested that higher injection speeds result in more stable processes when using 2-Stage processes. However, little data exists to verify this assertion. In this paper, injection speeds were varied on a 2-Stage process. Cavity pressure was measured at the end of the cavity to evaluate process stability in the face of several process perturbations. Results supported the claim that higher injection rates reduced overall process variation.
Toughening of Polypropylene with Calcium Carbonate Particles
In this paper the influence of precipitated calcium carbonate (PCC) particles on the toughening of polypropylene has been studied. It has been shown that the addition of the PCC particles increase the stiffness of the system and at the same time increase the impact resistance. The brittle-to-ductile transition temperature (TBD) was lowered considerably by increasing the calcium carbonate concentration. The debonding of the calcium carbonate particles prior to the yield stress is the dominating step in the toughening mechanism.
In-Line Compounding: Effect of Screw Design on Control Pressure Stability
In-Line" compounding is defined as any process in which both the compounding and the forming steps are performed at the same time. For these applications line stability is crucial and greatly effected by equipment selection and design. Presented is a brief overview of in-line compounding including control methods and factors effecting line stability. The pumping efficiency of various screw elements is established and their effect on control pressure stability examined. A modified screw design is presented which is found to produce a more stable control pressure."
Effect of Crystallization Conditions on Spherulitic Texture and Tensile Properties of sPS/PPO Blends
Syndiotactic polystyrene (sPS) and poly(phenylene oxide) (PPO) blends, miscible in melt state, were crystallized from melt as well as quenched state at different temperatures. The effect of processing conditions on spherulitic texture, ultimate tensile properties and the mode of fracture was studied. The study suggests that by varying composition and processing conditions in melt miscible blends it is possible to control amorphous domain sizes, which is critical in achieving better mechanical properties
CPI In-Line Compounding Systems
Composite Products, Inc. has commercialized in-line compounding technology to produce long fiber thermoplastic composites. Turnkey systems continuously compound thermoplastic resin with reinforcements ie. ½ inch chopped glass, carbon or natural fibers to produce finished composites with outstanding toughness. The separation of thermoplastic melt processing and the introduction of glass is key to fiber length retention. The patented technology provides molders the ability to maintain the highest level of physical properties while molding appearance parts. or strongly reduce
Conductive TPO for Electrostatic Painting
The TPO (Polypropylene/Elastomer) market for injection molded automotive bumper fascia is driven by cost reduction, a balance of physical properties, ease of processability, and desirable aesthetics. Global volume for this application was approximately 740 MM lbs. in 1999, nearly half of which is electrostatically painted. Decreased application costs, increased productivity, and reduced environmental emissions can be realized through system optimization. This report describes the rheological and morphological phenomena governing the development of a conductive TPO (CTPO) for enhanced electrostatic painting.
Blends of Recycled Polyethylenes and Metallocene Impact Modifiers for Rotational Molding
This paper describes the development of blends of recycled polyethylenes suitable for rotational molding. The blends consist of recycled post-industrial polyethylene resins and polyolefin plastomer impact modifiers, produced by single-site (metallocene) catalysts. The rheological properties of the blends were found to be favorable for rotational molding. Rotomolded parts provided satisfactory low temperature impact strength and good tensile properties.
Toughening Mechanisms in Fiber-Containing Impact Modified Polymers
An attempt was made to separate the toughening arising from the presence of fiber and that from the toughened matrix using the essential work of fracture. Toughening mechanisms with fiber inclusions were found to be associated with fiber bridging, debonding and pull-out. It was concluded that such fiber toughening would yield a flat curve when the specific total fracture work was plotted against the ligament length. The technique was able to produce fruitful information regarding design for property synergism in impact modified nylon 6,6.
Welding of a Thermoplastic Elastomer
This paper shows first results of examinations of the weldability of a thermoplastic elastomer (TPE). The examinations apply to an EPDM/polypropylene-blend. Three kinds of this TPE were welded with different parameters and the quality has been determined with mechanical and structural examinations. These first results show that the welded EPDM/PP-blends have remarkable tensile strengths. But the weld seams allow low strain as the base material. Also shows the examinations a different allocation of the hard" and "soft" components of a thermoplastic blend along the weld seam toward the base material."
Prediction of Transient Material Functions of PP Resins Using the Multi-Mode PTT Molecular Network Model
The transient rheological material functions [?(t,?),N1(t,?),?e(t,?) ] of three PP resins are predicted using the multi-mode Phan-Thien and Tanner (PTT) molecular network model. The study also includes the standard quality properties (MFI, XSP, GPC, and DSC) of the resins. The model was coded in C-language, validated with published data (Phan-Thien, 1978) and then used for the prediction of transient material functions. The predictions are in good agreement with the resins' rheological data.
An Experimental Comparison of the Improved Mixing Obtained from a New Barrier Screw Design
A comprehensive study looking at both distributive and dispersive mixing for a new screw design was done on a single screw extruder. The findings showed an improvement in mixing performance with this new style barrier screw over a conventional barrier screw design. Mixing performance was evaluated by means of microscopic analysis. To better quantify mixing three different systems will be studied; distribution of a pigment, distribution of an inorganic filler, and dispersion of a minor component in an immiscible blend.
Probing Local Chemical Interactions and Bond Energies with AFM
Atomic force microscopy has been utilized to examine molecular interactions of native and OTE modified silica surfaces under aqueous conditions. For native silica, depending on pH, the measured adhesion consists of convolutions of different interactions, including hydrogen bonding, anionic hydrogen bonding and covalent bond breaking. Modification with OTE allows for hydrophobic interactions to be probed, and time dependent adhesion results suggest the possibility of probing molecular reorganization within the contacts.
Polymer Blend Morphology by Dynamic AFM
The reduction in lateral forces during scanning allows the tapping-mode AFM to be an extremely useful tool for evaluating the morphology of polymer blends. Without staining or etching, rubber/plastic domains and fillers in cryo-faced polymer blends can be obtained with strong contrast. Subsequent image processing and measurement of AFM micrographs can provide quantitative structural parameters in blends. Filler partition in polymer blends, compatibility and interfacial tensions between polymers, and filler and phase networking can be measured.
Chemical Imaging with near Filled Scanning Optical Microscopy
The ability to measure chemical bond changes on the nanometer scale is of critical importance for the characterization of catalytic processes, catalytic materials, and surfaces relevant to materials and biological problems. Our goal has been to develop a technique for in-situ, non-destructive measurements of site-specific chemistry on the nanometer scale. The strategy for realizing this goal involves coupling the high spatial resolution of near-field scanning optical microscopy (NSOM) with the chemical specificity of vibrational spectroscopy.
In-Mold Decorating of Plastic Parts
In-mold decorating is a technique with a long history. However, recent developments have created new opportunities for designers. This paper discusses these techniques and how they are applied to plastics.
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