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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Thermoplastics Materials and Foams
incorporating Unmodified Lignin into Flexible Polyurethane Foams Formulation
Akash Gondaliya, May 2020
Industries that use polyurethane foam are looking for new sustainable and greener material to replace the petroleum-based polyols. Lignin produced as byproduct of pulp and paper and bioethanol industries is a suitable natural polymer to replace petroleum-based polyol in formulation of PUs. The emphasis was to study effect of different lignins obtained from different chemical processes and plant sources on the structural, mechanical and thermal properties of PU flexible foam and to achieve maximum lignin substitution. Additionally, we were interested to find correlation between lignin properties and performance of lignin-based PU foams to identify which lignin properties would affect the performance of developed lignin-based flexible PU foams and find the most suitable lignins for this application. It was seen that lignins isolated through organosolv process were better for PU fiexible foam applications. Overall, substitution of polyol with lignin increased compression strength, support factor, tear propagation strength and tensile strength of the developed PU foams.
Numerical Analysis of Polymer Micro-foaming Process in Extrusion Flow
Lixia Wang, May 2020
In this paper, effects of microviscosity and wall slip were considered, and a mathematical model of isothermal extrusion micro-foaming process was adopted based on classical nucleation theory and cell model. A simulation scheme of the extrusion micro-foaming process was conducted combining with the cross-section/imaginary area method and the Runge-Kutta method. The simulation program of the extrusion micro-foaming process was realized on MATLAB. The effects of inlet pressure on evolution of cell morphology and cell size distribution during the extrusion micro-foaming process were analyzed by the numerical examples. The results indicate that the higher the inlet pressure, the higher the maximum nucleation rate, and the closer to the die outlet the nucleation spot, the shorter the growth distance of the bubble, which is more conducive to formatting smaller cell radius and higher cell density.
‘Plug-and-Play’ Weight Reduction Solution by Hollow Glass Microspheres
Steve Amos | Baris Yalcin | Andrew D’Souza | I. Sedat Gunes, May 2011
Fillers have been in use since the early days of plastics. Today’s enormous growth of the polymer industry is due to the unique properties of fillers they impart to polymers. Glass bubbles (low density hollow glass microspheres) as fillers have been incorporated into thermoset polymers for decades. They are tiny hollow spheres and are virtually inert. These glass bubbles are are compatible with most polymers. Until recently, their use with thermoplastic polymers has been limited because of high rates of bubble breakage from the high shear forces to which they are exposed during such thermoplastic processing operations as extrusion compounding and injection molding. At issue has been the strength of the glass microspheres.
Water Vapor Transport Properties of Shape Memory Polyurethane Nanocomposites
I. Sedat Gunes , Feina Cao , Sadhan C. Jana, May 2010
In this paper water vapor permeability (WVP) of thermoplastic polyurethane nanocomposites with crystalline soft segments was evaluated. Organoclay nano-size silicon carbide (SiC) and a high structure carbon black (CB) were mixed with shape memory polyurethane (SMPU) based on semi-crystalline soft segments. All nanocomposites were prepared by bulk polymerization using a Brabender internal mixer. Compression molded specimens were used in the determination of WVP. The results indicated that the presence of silicon carbide augmented WVP by reducing the soft segment crystallinity whereas that of organoclay reduced the WVP considerably due to excellent exfoliation.
Wood Plastic Composite
Prithu Mukhopadhyay, February 2006
Wood and plastic are best friends these days. They can be combined to give the aesthetics of wood with the added durability of plastic. Termed as wood/plastic composites - WPCs' are a relatively new family of thermoplastic composites based on wood-fibres and the commodity thermoplastics. The polymers used for WPCs' are the high volume, low cost, commodity thermoplastics - polyethylene, polypropylene and PVC.
A Breakthrough in Foaming Technology
Prithu Mukhopadhyay, March 1999
MuCell process by Trexel Inc. has been touted as a breakthrough technology. The process offers new foaming capabilities. If your business belongs to the categories such as Extrusion (PP, PS sheet & PVC profiles), Blow (HDPE bottles) or Injection moulding (PP, PS, Nylons, PC/ABS and TPEs) then you will profit from MuCell process. The process produces microcellular foams (5-50 micron ranges) using supercritical fluids (SCFs). These fluids like carbon dioxide or nitrogen mix thoroughly in plastic melt since they have the viscosity of gases and the density of liquids. Being environmentally benign, SCFs eliminate the need for chemical or hydrocarbon-based blowing agents. CO2 or N2 are in fluid state as opposed to gas (in gas assist injection moulding); the process generates evenly distributed microscopic cells throughout the plastic. This makes MuCell technology to foam very thin sections (0.5mm/0.20inch).
Mix & Match: New Developments Offer New Applications
Prithu Mukhopadhyay, November 1998
Injection molding process imparts a complex thermal deformation history to polymer melts. The complexity rises with multiphase blend systems. How about development in areas of new materials? Can we not get new resins that would give faster cycle times, high ultimate strength and elongation values combined with a wide spectrum of shore A and shore D hardness grades?
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