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.
The change in pressure drop and pressure drop rate at the gate of the mold during the structural foam molding process results in an inevitable nonuniform void fraction along the melt flow direction in injection molded structural foams. The nonuniform void fraction not only reduces the achievable void fraction but also can deteriorate the mechanical properties of structural foams. In this paper, an effort has been made to overcome this problem with various injection speed profiles.
The melt rheology of novel Olefin Block Copolymers (OBCs), recently developed by The Dow Chemical Company, was investigated. The melt shear rheology of OBCs was found to be characteristic of linear random copolymers of ethylene and __olefins. Furthermore, the melt rheology can be modified to target certain specific application areas by chemical means or by blending with traditional polyolefins with broader molecular weight distributions or those containing long chain branching.
The effect of well-dispersed carbon nanotubes on the crystallization characteristics of polyethylene-oxide was studied. The specimens were prepared via the solution-sonication procedure. The results confirm the effectiveness of CNTs as nucleation agents for semi-crystalline polymers.
The Fracture behavior of Medium Density Polyethylenes (MDPE) with different melt flow indexes (1.9 to 5.0 dg/min) employed in rotational molding were studied by Essential Work of Fracture (EWF). The EWF parameters obtained were equivalent for all samples examined regardless of their differences in comonomer content and molecular weights. Annealing of samples resulted in lower ductility values according to EWF parameters, in spite of minimum crystallinity changes.
In this study, the effects of processing parameters on cell morphology and mechanical properties of PLGA 50/50 bioscaffolds for tissue engineering applications were investigated. The PLGA samples were processed using a salt leaching technique in a batch foaming setup. The foaming parameters were varied, and the physical and mechanical properties of the scaffolds were investigated.
This work investigates improvement techniques used with 3D printed metal parts during the infiltration treatment. By extending the infiltration cycle and applying a planar contact surface to the face of a sample, reductions in roughness of 76% are possible. The goal is to produce injection mold tooling with an acceptable surface quality without performing a secondary machining process.
The use of UV coatings, inks, and adhesives on thermoset and thermoplastic substrates continues to grow at a rapid rate. UV and electron beam curing has moved from primarily curing of inks to functional and decorative coatings. One of the areas with the highest growth rate is the use of industrial coatings on 3D parts. Processing of 3D part presents a number of challenges – the critical process challenge is that UV curing requires line-of-sight to achieve activation and cure.
Unless it can be properly crystallized, the field of applications for poly(lactic acid) will be limited by its low glass transition temperature. This paper discusses different strategies that can lead to partial crystallization within typical polymer processing conditions. X-ray techniques and DSC analysis are used to access the crystalline content developed in various molding and extrusion conditions and as a function of plasticizer and nucleating agent content.
For a number of polymers with different chemical structures and different properties, we have determined scratch resistance and sliding wear. We have determined cross section areas of the grooves including the groove and side top-ridge areas. The nanohardness of the polymers was also determined using nanoindentation testing both inside and outside the grooves. A relationship between the hardness and the groove areas has emerged.
A series of colorants including yellows, reds, blues and greens have been evaluated when processed with monomeric and oligomeric HALS in PP and HDPE. Comparisons have been done in masstone and tint looking at effects on color shift and strength.
A comparison between commercially available and a newly developed thermal management coating applied to steel substrates is presented. A successful coating must protect a thin 76 by 152 mm steel plate during a direct flame test and withstand low temperature flexural tests without cracking or delaminating. The only coating to meet both requirements is the newly formulated composite consisting of fiberglass in a silicone matrix.
Advances in vibration welding tooling and machinery will offer manufacturers of center consoles a cost effective alternative to current methods. This concept will offer improved manufacturing flexibility and enhance overall performance. We will discuss the tooling and machine concept. This concept is the first of its kind and addresses the issues associated with welding multiple thermoplastic parts in a single operation using the vibration welding process. The tooling and concept are patent pending.
Polystyrene (PS) thin films were spun-coat on graphite and silicon oxide surfaces to resemble the polymer-substrate interface in carbon and organoclay based nanocomposites. The film thickness was varied and the apparent glass transition temperature (Tg,a) were investigated by using nanoparticles embedding technique. The PS on these substrates shows different Tg,a profiles, depending on the polymer-substrate interactions. These results will provide valuable guides for rational design of new polymer nanocomposites.
Sharkskin and melt fracture phenomena have been investigated in two commercial biodegradable polyesters– aliphatic-aromatic co-polyester (AAC), poly(lactic acid) (PLA) and their blends. The study was conducted in a two bore capillary rheometer. It was observed that at high shear rates and stresses PLA exhibits sharkskin and gross melt fracture, while AAC exhibits only gross melt fracture. Experiments indicate that the blends exhibit both phenomena and that blending is beneficial for postponing the onset of flow instabilities to higher shear stresses.
In any polymer blend system, the nature and thickness of the polymer interface can have a significant influence on the overall performance of the blend. AFM in tapping mode (TMAFM) was employed to establish a systematic methodology to quantitatively measure the relative interface thickness in coextruded multilayer films.
This paper presents photografting as a surface modification method to provide permanent wettability improvement to deep-groove polypropylene (PP) fibers. We also describe approaches to evaluate the wettability of these fibers and the wicking performance of fiber bundles when polyacrylamide (PAAm) was grafted onto the fibers. In this study, the concentration of the monomer and the UV-exposure time were altered to examine the effects of those variables on fiber hydrophilicity. Results showed lower water contact angle and improved wicking capacity upon modification with PAAm.
Joining and adhesive properties of polymeric composites are of critical importance for emerging applications in the aeronautical, aerospace and marine industries. Traditional macroscopic adhesion testing techniques evaluate macroscopic properties of materials, with limited information on the molecular level processes that control actual performance. Nanomechanical and nanotack evaluations utilizing advanced nanoprobe techniques of polymer/fiber composites reveal differences in performance at the molecular level.
Highly filled polymeric materials exhibit complex rheological properties. In this study the rheological characteristics of highly filled suspension based on ethylene octane copolymer binder and Dechlorane filler were studied. Steady shear and thixotropic behaviors are discussed.
Thermal residual stresses, internal fuel pressure and acceleration stresses during launch stage were evaluated and quantified for cryogenic composite fuel tank design. Fuel leakage induced temperature variation through laminate thickness after initial cracking was applied to a progressive failure analysis. Comparison of the results with conventional failure analyses was performed. Critical temperature and pressure conditions for failure initiation and whole laminate cracking were found based on the failure analysis.
The luminance of an injection molded V-groove light-guide plate (LGP) was found to be affected by the depth of melt filling of the grooves. Imperfections in filling are influenced by local pressure and temperature histories. The measurements of the depth of melt filling were carried out at different locations using two optical grade polycarbonate (PC) moldings obtained at various processing conditions.
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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
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