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
NEW ENVIRONMENTALLY PROGRESSIVE POLYESTER and POLYESTER/POLYCARBONATE FR RESINS
New family of ENH flame retardant PBT (polybutylene terephthalate) and PBT/PC(polycarbonate) thermoplastic resins developed is aimed at helping electrical/electronics (E/E) manufacturers and suppliers comply with regulations restricting use and disposal of hazardous substances. The non-chlorinated, non-brominated FR PBT and PBT/PC products deliver similar mechanical, physical, thermal and flame retardant performance compared with their brominated FR based counterparts. Some of those resin properties will be discussed in this publication.
TRANSIENT MOLD COOLING SIMULATION FOR THE INJECTION MOLDING PROCESS
In recent years, injection molding technologies have been developed which use variable mold heating and cooling to increase part quality without significantly increasing cycle time. These processes are not suited for simulation with a conventional steady-state (cycle-average) mold thermal analysis. This paper presents the development of a new 3D finite element based transient mold cooling simulation capability which includes coupling the mold thermal solution with the mold filling and packing simulation. The predicted transient mold temperatures are validated against measured mold temperatures for two instrumented injection molding trials.
MORPHOLOGY AND STRENGTH OF INJECTION MOLDED PARTS WITH INTERFACES
The specific interfacial morphology and strength of paired polymers will be discussed. The focus is on two different types of interfaces during injection molding processes: (I) hot interface represents two melt streams meeting (weldline) and (II) cold interface is defined as the overmolding of a second melt to a chilled, hardened preform. A cold interface occurs during a multi-shots injection molding process. Regarding the strength amorphous and semicrystalline polymers were used, for the visual inspection of interfacial morphology by light microscopy semicrystalline POM was investigated. In conclusion, new aspects about a correlation between interfacial morphology and bonding strength are addressed.
ENVIRONMENTALLY PROGRESSIVE PBT BASED ENGINEERING THERMOPLASTICS PRODUCT PORTFOLIO FOR AUTOMOTIVE AND ELECTRICAL APPLICATIONS
This paper provides insights into a newly launched portfolio of environmentally progressive products. These molding compositions are based on a polybutylene terephthalate (PBT) that is made by chemical regeneration of post consumer recycle polyethylene terephthalate (PCR PET) and converted into PBT. These products can then be used in a variety of automotive and consumer applications. These new products' manufacturing processes require less energy and non-renewable fossil fuels as compared to the manufacturing processes of conventional fossil fuel based materials. We will present the comparison of properties results of molding compositions using this new technology and traditional PBT will be presented.
SYNTHESIS AND CHARACTERIZATION OF NOVEL POLYCARBONATE-POLYDIMETHYLSILOXANE BLOCK COPOLYMERS WITH CONTROLLED BLOCK LENGTHS AND AN ALTERNATING BLOCK ARCHITECTURE
A novel method to synthesize polycarbonate-polydimethylsiloxane block copolymers with controlled block molecular weight and an alternating block architecture was investigated. The method investigated consisted of the synthesis of polycarbonate oligomers/polymers possessing allyl-functional endgroups and the subsequent coupling of the oligomers/polymers with hydride-terminated polydimethylsiloxane oligomers/polymers using hydrosilylation. GPC and NMR were used to demonstrate successful block copolymer formation. Characterization using AFM showed nanoscale phase separation. The optical clarity of a PC-PSiO block copolymer produced with this method was significantly better than that of a commercially available PC-PSiO block copolymer, indicating smaller PDMS domains resulting from the more uniform block copolymer structure.
A NEW FOCUS ON TEMPERATURE EVALUATION FOR GAS SAVING IN A ROTATIONAL MOULDING OVEN
The temperature of an oven named OPT are evaluated. Two types of moulds, an aluminium ball-like and stainless steel cube-like, were used. Finite element software was used to find a combination of hot air flow velocity and the oven internal surface geometry. The temperatures obtained in the OPT were compared with temperatures obtained in Benchmark oven. For validation purposes the OPT was compared with simulations. The agreement between the OPT and the ROT time-temperature curve behaviour is remarkable. The OPT gas consumptions are compared with in an oven named here the Kearns found in the literature.
NANOSCALE INFRARED SPECTROSCOPY OF BIOPOLYMERIC MATERIAL
Atomic Force Microscopy (AFM) and infrared (IR) spectroscopy have been combined in a single instrument capable of producing sub-micron spatial resolution IR spectra and images. This new capability enables the spectroscopic characterization of microdomain-forming polymers at levels previously impossible. Films of poly(3-hydroxybutyrate-co-3-hydroxyheanoate) were solution cast on ZnSe prisms. Dramatic differences in the IR spectra are observed in the 1200-1300 cm-1 range as a function of position on a spatial scale of less than one micron. This spectral region is particularly sensitive to the polymer crystallinity, enabling the identification of crystalline and amorphous domains within a single spherulite of this copolymer.
RHEOLOGICAL EFFECTS ON FOAM PROCESSING IN ROTATIONAL MOLDING
Rheological properties of several polypropylene polymers were measured and the foam processing of these materials using chemical blowing agent was studied. Foaming was carried out in monolayer and skin-foam layer moldings. The uniaxial extensional viscosity was quantified and the foam characterized based on bulk density, bubble size, and bubble concentration. It was found that the foam processing window is determined and bounded by melt viscosity and melt elasticity. Melt strength and strain-hardening can substantially improve the foaming performance and play significant role in determining the developed morphological structure.
STUDY ON THE PROCESS PARAMETERS TO IMPROVE STRENGTH OF WPC PREPARED BY A NOVEL COMPRESSION MOLDING SYSTEM
It was found that compression molded Wood Plastic Composites (WPC) show lower strength than the extruded WPC which could be due to lower net alignment of the reinforcing fibers and lower inter-diffusion and alignment of the polymer chains due to the smaller net flow of material during processing. To test this hypothesis, a new compression molding system was developed where materials were forced to flow in one direction. Comparative strength studies of WPC, prepared by this novel compression molding system, have been presented at varying speed and temperature of die-press. The initials results seem to validate our hypothesis.
FILLER RE-AGGREGATION AND NETWORK FORMATION TIME SCALE IN EXTRUDED HIGH DENSITY POLYETHYLENE / MULTI-WALLED CARBON NANOTUBE COMPOSITES
Multi-walled carbon nanotube (MWNT) / high density polyethylene (HDPE) composites with varying amounts of carbon nanotubes were investigated and the effect of MWNT weight fraction on their electrical conductivity, crystallinity and mechanical properties is presented here. Samples were prepared by melt dilution of a HDPE masterbatch containing 20.2 wt% MWNT with varying amounts of neat HDPE. The effect of extrusion processing on the formation of an electrically conductive MWNT network in extruded samples was assessed by the addition of a low-shear annealing zone (shear rate 1-10 s-1) before final extrusion through a die and it is also discussed here.
INVESTIGATION OF THE RELATIONSHIP BETWEEN CELLULAR AND MECHANICAL PROPERTIES OF INJECTION FOAM MOLDED POLYMER COMPOSITES
Microcellular injection foam molding technology can bring a number of advantages to the existing conventional injection molded products such as lower density, material cost reduction, reduction of residual stress, better dimensional stability, reduction of cycle time, and better dispersion of fillers. However, the technology has not been fully employed yet, especially in the automotive sector, because injection foam molded parts, in general, experience a decrease in mechanical strengths. Therefore, this research studies the relationship between cellular and mechanical properties of the two common polymer composites in the automotive industry, which are glass-fiber reinforced plastics (GFRP) and wood-fiber polymer composites (WPC).
OXIDATIVE STABILITY OF VITAMIN E INFUSED, HIGHLY CROSSLINKED POLYETHYLENE FOR ORTHOPEDIC APPLICATIONS
In this paper, highly crosslinked and vitamin E infused (VITE) ultra-high molecular weight polyethylene is evaluated for mechanical properties, oxidation resistance, and wear. Testing included small punch mechanical properties, impact strength, a fatigue study, and knee wear simulator testing. The VITE material showed no evidence of oxidation and no decrease in the mechanical properties with accelerated aging. The VITE material showed an 86% reduction in wear over the control. The combination of crosslinking and vitamin E infusion produced a polyethylene material with improved wear properties and superior oxidation resistance suitable for use in orthopedic applications.
Application of Variational Asymptotical Method for Unit Cell Homogenization (VAMUCH) in the Prediction of Mechanical Properties for Microcellular Plastics
This study presents the application of Variational Asymptotical Method for Unit Cell Homogenization (VAMUCH) with a three-dimensional unit cell (UC) structure and finite element analysis for analyzing and predicting the effective elastic properties of microcellular injection molded plastics. A series of injection molded plastic samples with microcellular foamed structures were produced and their mechanical properties were compared with predicted values. The results show that for most material samples, the numerical prediction is in fairly good agreement with the experimental results, which suggests the applicability and reliability of VAMUCH in analyzing the mechanical properties of porous materials.
PRELIMINARY RESULTS IN RHEOLOGICALLY OBTAINING MODEL PARAMETERS FOR THE PURPOSE OF PREDICTING THE ORIENTATION OF CONCENTRATED LONG GLASS FIBERS IN PROCESSING FLOWS
The purpose of this research is to understand the transient fiber orientation of long glass fiber (> 1mm) reinforced polypropylene, in a well-defined simple shear flow (using a sliding plate), by determining unambiguous model parameters from rheological experiments, and to ultimately predict fiber orientation in complex processing flows. Two fiber orientation models were investigated. One model, the Folgar-Tucker model, has been particularly useful for short glass fiber systems and was used in this paper to assess its performance with long glass fibers. A second fiber orientation model, one that accounts for the flexibility of long fibers, was also investigated.
RHEOLOGICAL CHARACTERIZATION OF POLYPROPYLENE MIXED WITH SPECIALLY MODIFIED CALCIUM CARBONATE
The rheological properties of polypropylene filled with specially coated calcium carbonate were investigated in this study. CaCO3 fillers were coated in order to further improve the mechanical and flow properties of the filled polymer. A fluid energy mill (FEM) was used to simultaneously mill and coat the calcium carbonate particles. Both rotational and capillary rheometers were utilized to study the rheological impact of the coated particles. The rheological properties of the specially coated particles were compared with non-coated particles at similar concentration. Shear viscosity, dynamic viscosity and also melt flow index were determined at three different temperatures.
AGING DEPENDENT SLIP AGENT SURFACE MORPHOLOGY OF LLDPE FILMS
The ability to maintain stability of coefficient of friction (COF) for low density polyethylene (PE) films has been a persisting issue for the flexible food and specialty packaging industry. We conducted a systematic study monitoring the change on slip agent coverage and morphology change on PE film surfaces including films aged at room temperature and at elevated temperatures. We found significant change in slip agent morphology on the film surface over long aging time at room temperature. This paper describes our investigation on erucamide, a slip agent, surface coverage and its morphology changes with respect to aging time and temperatures.
RHEOLOGICAL CHARACTERIZATION OF POLYCARBONATE RESINS AND ITS APPLICATIONS
We show results of rheological testing of polycarbonate resind and its applications. Rheological characterization provides indirect measurements of materials properties, such as molar mass and molar mass distribution. Dynamic storage Gƒ?? and loss Gƒ? modulus represent elastic and viscous properties of the material. Viscosity curves give information about materials behavior under different temperatures and shear rates. Dynamic mudulus and zero shear viscosity can be used as qualitative parameters to characterize and distinguish different materials, and to predict materials performance. Rheological data can be used for process optimization and quality control.
ORDERING KINETICS OF BLOCK COPOLYMER SOLUTIONS DURING SOLVENT REMOVAL
The ordering kinetics of block copolymers in solution are studied during a solvent removal process. The kinetics of styrenic block copolymers in a neutral solvent, toluene, are tracked at various concentrations along a drying path to determine the effect of concentration on phase separation. The ordering process is modeled with the Avrami equation. Small angle X-ray scattering has been used to determine that the structures developing during solvent removal are cylinders. Scattering data also indicates that the concentrations studied by the rheology experiments are limited by the conditions under which samples are dried.
MODELING AVERAGE CAVITY TEMPERATURE USING ARTIFICIAL NEURAL NETWORKS
Average cavity temperature has been shown to be a suitable control variable in obtaining repeatable part quality. Existing control schemes for average cavity temperature use on-line and off-line identification techniques to formulate system models. These models are often linearized about a specific operating region and introduce inaccuracies in control due to process nonlinearities. This work presents an online artificial neural network black-box system identification routine to model the nonlinear dynamics of the average cavity temperature with respect to mold and process conditions.
LOW-DENSITY POLYETHYLENE COMPOSITES FILLED WITH CERAMIC FILLERS FOR ELECTRONIC PACKAGING APPLICATIONS
This study details the fabrication of linear low-density polythene (LLDPE)-based composite materials containing silicon carbide (SiC) and boron nitride (BN) filler particles. The composites were created by using a twin-screw compounder, and evaluated based on their morphology, as well as their thermal, electrical, and mechanical properties. Overall, the addition of ceramic fillers increased the thermal conductivity of the composites, without compromising the electrical resistivity, which is desirable for electronic packaging and heat management components in microelectronics.
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