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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Kinetic Studies of Reactive Blending of Thermoplastic Polyurethanewith Poly(Vinyl Chloride) to Apply for Reactive Extrusion
The polymerization kinetics of thermoplastic polyurethanes (TPU) is studied by using differential scanning calorimetry (DSC), Raman spectroscopy, adiabatic temperature rise (ATR) and dynamic rheometry. The objective of this study is to develop the empirical kinetic equation(s) governing the TPU polymerization in a twin screw extruder, as well as including the effects of chemical structure, isomerism, NCO and OH content, catalyst and temperature on the TPU polymerization. The polymerization during the reactive blending process with Poly(vinyl Chloride) (PVC) is presented. The effects of shear rate and pressure on the kinetics model are also considered.
Ultrasonic Plastic Welding: Weld Processing Modes, Their Descriptions, Functions and Applications.
Modern ultrasonic welding systems are capable of processing a wide array of thermoplastic parts and materials by using different welding modes. Determining which mode of operation can be intimidating to the user uninitiated with the applicability and intricacies of each. Welding by time, energy output, peak power output, distance (either reference point or absolute), or even combinations thereof, are all offered on advanced ultrasonic controllers each with its own advantages for a specific welding operation. This paper will explain each mode while suggesting different modes and strategies for the optimization of different types of welding processes performed on various products and materials.
Residence Time and Deformation Characteristics of the Real Screw Extruder
We consider distributive mixing in the single-screw extrusion process. Several mixing measures in the extrusion process were proposed in the literature to quantify the mixing performance. In our previous research, we proposed the “Deformation Characteristics” (DC) as a new deformation measure of the screw extrusion process using the Cauchy-Green deformation tensor.In this work, the fourth-order Runge-Kutta method has been employed for numerical integrations to obtain the residence time and the deformation characteristics, using the three-dimensional velocity fields obtained by the finite element analysis with the periodic boundary conditions along the down-channel direction in the real screw geometry.
The Effect of Primary Runner Length on Fill-Imbalance in a Geometrically Balanced Eight Cavity Polymer Injection Mold
This study investigates the effect primary runner length has on fill imbalance characteristics for a geometrically balanced multi-cavity runner system, during a polymer injection molding process. The experimentation utilizes three settings of the primary runner length – long, medium, short – and four injection velocity settings, creating a relationship of fill imbalance to both the primary runner system’s length-to-diameter ratio (L/D) and injection velocity. The experiment’s goal is to provide data that would build on prior studies’ findings on the topic of shear induced flow imbalances in geometrically balanced molds.
CO2 Foaming Based on Polystyrene / Poly(Methyl Methacrylate)Blend and Nanoclay
Poly(methyl methacrylate) (PMMA) and nanoclay composite was blended as a dispersed phase with polystyrene (PS) in a twin-screw extruder. The mixture was then batch foamed with supercritical CO2. It was found that the cell density of foams based on the blend is higher than that based on the weight average of the two pure polymer components at the same foaming conditions. The cell size decreases and the cell density increases with the increase of the PMMA domain size. One explanation is that large PMMA domains serve as a CO2 reservoir and the nucleation in the PS phase is enhanced by the diffusion of CO2 from the PMMA phase to the PS phase. Very small PMMA domains can not function as CO2 reservoir, so they are not able to facilitate nucleation. A much higher cell density and smaller cell size were observed when nanoclay is located at the interface of the PMMA and PS domains due to the heterogeneous nucleation.
Controlling Warpage through Melt Rotation Technology
During the injection molding process, high shear conditions developed in the runner can create significant material and melt temperature variations across its diameter. As the melt continues into the cavity, laminar flow conditions segregate these melt variations and cause them to be distributed into distinctly different regions within the part. The resultant uncontrolled distribution of these melt variations may be the root cause of warpage in many plastic parts. It must be understood that these melt variations cannot be controlled by the molding machine. However new methods demonstrated in this paper show that they can be controlled within the melt delivery system of the mold. This paper presents the results of a study which proves that the segregated melt conditions developed in a runner are a significant contributor to warpage. Additionally the paper presents new methods of controlling the resultant warp through the strategic positioning of these melt conditions within the part.
Surface Modification and Bulk Properties of PLA, PHA, and Their Blend Films
The major objectives of this research are to modify the surface characteristics of poly(L-lactic acid) (PLA), a poly(hydroxyalkanoate) (PHA), and their blend films by grafting hydrophilic polymers and to study the effect of the surface modification on bulk properties of these films. The surfaces of solvent-cast films were activated by UV irradiation. Hydrophilic monomers acrylic acid and acrylamide were then photopolymerized from the film surface. The film surfaces resulting from each reaction step were analyzed using ATR-FTIR spectroscopy and contact angle goniometry. The effect of the surface modification procedure on the bulk properties of the films was studied to determine whether properties were adversely affected. Representative bulk properties, including Young’s modulus, tensile strength, % elongation, and toughness, were measured after photografting.
Vibration Welding of Nylon 6 Nanocomposites
Nanoclay composite materials provide low specific gravity and high modulus properties that are superior to many other composite materials. Recent developments in Nylon 6 nanoclay composites have achieved more than a 100 % increase in flexural and tensile moduli with 8 wt% total nanoclay loading; total nanoclay referring to the sum of the organic surfactant and inorganic clay content. However, the weldability of nylon nanocomposites has never been reported. This study evaluated the weldability of nylon 6 nanocomposites with 0 wt%, 5 wt% and 8 wt% total nanoclay loadings using vibration welding. A threefactor (weld pressure, weld amplitude and meltdown) and two-level DOE was conducted to evaluate the weldability of these materials. It was found that the weld strength of the 8 wt% nanoclay loaded nanocomposite was 19% lower than the unfilled nylon 6.
Deformation and Orientation of PET Filament via High Speed In-Line Drawing
On-line measurement of birefringence was conducted in high speed in-line drawing process of poly(ethylene terephthalate) filament by using a diameter monitors and an optical retardation measurement apparatus. Birefringence of filament increased steeply in the vicinity of necking deformation and the position of that slightly shifted to upstream with increasing draw ratio. Birefringence measured in the spinning line showed lower values than that in the in-line drawing line at the same diameter, because the steep increase of birefringence started at larger diameter in the drawing process. On the other hand, time-course changes of diameter and birefringence in the vicinity of neck-like deformation in the spinning line could be clearly obtained, and it is important to note that the necking deformation in the high speed in-line drawing process occurs accompanying unique periodic diameter fluctuation of about 130 Hz.
Practical Applications of Polyethylene with Excellent Easy Processability
The melt rheological properties of an ethylene/alpha-olefin copolymer polymerized by a supported metallocene catalyst, which have been developed as the easy processing polyethylene by Sumitomo Chemical, were evaluated and compared with conventional polyethylenes. The melt viscoelastic properties of the copolymer exhibit a shear rate dependence similar to that of high-pressure low density polyethylene that is considered to be caused by the wide molecular weight distribution and long chain branched molecular structure.In the latter part of this presentation, we have focused on the performance of the above copolymer. This copolymer exhibited superior processability in the fabrication of blown film such as low temperature and high output processing, leading to the production of a clean film without any additives and with low odor and taste.
Superhydrophobic Valve for Microfluidics
Capillary valve (CV) is one of the passive valves used to control the fluid flow in microfluidics. Many designs and applications have been based on the capillary valve including the compact-disk microfluidic platform technology. However, the valve loses its function when being used to hold the protein solutions or subject to protein solutions which are applied to treat the surface for non-specific binding. A novel fishbone" micro-valve design based on the concept of superhydrophobicity was developed in this study. The experimental results showed that the valve remains its function even being subject to the protein solutions. It was also tested on the CD microfluidic platform in which the flow control was demonstrated during disk rotation under various conditions."
Mechanical Properties of Natural Hydroxyapatite/PP Composites
Cattle bone-based hydroxyapatite (HA) powders were prepared. Two types of silane coupling agents, i.e. vinyltriethoxysilane (VTES) and 3-methacryloxypropyltrimethoxysilane (MPTS) were used to modify the HA surface. Untreated HA powders and silane-treated HA powders were utilized to produce HA/polypropylene (PP) composites containing a 60% (w/w) of HA content. Effect of types and contents of silane coupling agents on mechanical and morphological properties of HA/PP composites were investigated. The results indicated that treating HA surface with a silane coupling agent enhanced tensile strength and Young’s modulus while reduced impact strength and flexural strength of the composites. Among various HA treating conditions, 2%-MPTS-treated HA provided the highest improvement of tensile strength and stiffness of HA/PP composites.
Using Reflectance Fourier Transform Infrared Spectroscopy and Contact Angle to Quantify Oxidation of Polypropylene
The objective of this investigation was to determine if Reflectance Fourier Transform Infrared Spectroscopy or contact angle measurements could be used to quantify surface oxidation of polypropylene. Contact angle was determined to not be useful as a measure of extent of surface oxidation. By contrast, the area of the carbonyl peak as measured by Reflectance FTIR was not only found to correlate well with exposure conditions, but the results were considerably easier to interpret. The peak area was found to correlate well with exposure time, UV exposure level, and the interaction between temperature and exposure time. These results suggest that Reflectance FTIR should be useful for quantitatively characterizing the level of oxidation of a polyolefin surface.
Effect of Processing Aids and Flame Retardant Synergists of HFFR Thermoplastics on Extrusion Processability and Flame Retardant Performances
Inorganic flame retardants, such as aluminum trihydrate(ATH) and magnesium dihydrate(MDH), are most widely used fillers in halogen-free flame retardant(HFFR) polyolefin materials, especially for wire and cable. These inorganic fillers are used in great amount, and influence the mechanical properties as well as flame retardancy significantly. Also, they commonly deteriorates the processability and raise a problem such as die lip buildup. Therefore, it is very important to reduce the inorganic filler contents in HFFR by the addition of flame retardant synergist. The effects of flame retardant compositions on the mechanical properties, flame retardancy and processing performance, especially die lip buildup characteristic, were investigated here.
Effect of Compounding Procedure on Mechanical Properties of PLA/PCL Blends
Umaru Semo Ishiaku, Hiroyuki Hamada, Division of Advanced Fibro-science, Kyoto Institute of Technology, Gosyokaido-cho, Matsugasaki, Sakyo-ku, JAPAN Side feeding technique was applied to Poly lactic acid (PLA)/Polycaprolactone (PCL) blend containing peroxide. Feeding procedures, such as blanket feed in which all the materials are fed into main hopper at once and split feeding using the side feeder, were attempted. The results indicate that tensile properties are not dependent on feeding procedure, but the impact strength was superior in the case of the split feeding samples. It is noteworthy that the impact strength of the split feeding sample was considerably affected as it was four times better. The size of the dispersed phase depends on the feeding procedure as the peroxide is more reactive when split fed.
9 Molds in 10 Weeks
As part of their major, Plastics Engineering Technology (PET) and Industrial Technology (IT) students at Western Washington University (WWU) are required to take a course in tooling design for plastics processes. The tools and technologies available to WWU Engineering Technology students allow for the complete design, construction, and implementation of an injection mold tool in the 10 weeks of the course.Students gained experience in the areas of tool design, program management, and problem solving while constructing their mold. Certain unique features on the molds will be used to illustrate the diverse solutions devised by the students. Every team used CAD/CAM software, CNC and manual mills, and a 40 ton injection molding machine available on campus to complete the projects. The mold design and construction exposed students to every phase of the mold design and manufacturing process.
Prediction of Non Linear Visco-Elastic Deformations
Long term deformations of complex products can be predicted using Finite Element Method (FEM) calculations. To demonstrate the possibilities of computer simulation of the long term behavior in the design stage an air inlet has been taken as an example.A problem in this prediction was to obtain accurately measure relevant creep and recovery data.Before carrying out FEM calculations the non-linear material behavior must be modeled in an appropriate way for the FEM calculations.The long term deformation can be predicting using commercial FEM programs like MSC-MARC. User subroutines are required to carry out analyses accounting for the non-linear visco-elastic behavior.Experimental verification is required to obtain confidence in the material modeling and the non-linear viscoelastic FEM calculations.
Woven Glass Fabric Composites via In-Situ Polymerized Cyclic Butylene Terephthalate Oligomers
The possibility of fabricating continuous fiber thermoplastic composites has been limited by the inherent difficulties associated with the thermoplastic matrices, such as high processing temperatures and high melt viscosities. This problem, to a certain extent, has been solved via the development of cyclic oligomers which is a low viscosity prepolymers that can be injected into the mold and polymerized in-situ. One of the main types of cyclic oligomers is cyclic butylene terephthalate (CBT). Woven glass fabric (WGF) reinforced in-situ poly(butylene terephthalate) (ISP-PBT) composites were fabricated by compression molding. Tensile, three-point flexural and short beam shear tests were carried out to investigate the effect of WGF on the mechanical properties of the resulting PBT composites. Microstructural features have been investigated by differential scanning calorimetry (DSC) and scanning electron microscope (SEM). The incorporation of 50 vol.% WGF into ISP-PBT resulted in significant enhancement of both stiffness and strength. Fractographic analysis not only revealed good interfacial bonding between ISP-PBT matrix and WGF but also uniform fiber dispersion in the composite.
Numerical Simulation and Experimental Study on Metal Injection Molding
Metal Injection Molding (MIM) is a process to manufacture metal parts, combining powder metallurgy with plastic injection molding. This paper deals with experimental and simulation study on MIM process. 3D numerical simulation was performed by using commercial CAE software with considered material database. To understand actual flow behaviors in MIM process, MIM was also performed at various molding conditions, and change of internal cavity pressure and the appearance of MIM products were evaluated. The simulation results were in agreement with the experimental values when the solidification effects on these material parameters were taken into account in this simulation. Especially, solidification temperature is very important parameter for estimation of flow behavior in MIM process.
Structure Evolution in ?- and ?-Polypropylenes Under UV Irradiation
Commercially available isotactic polypropylene (PP) was modified by a specific ?-nucleating agent based on N,N´-dicyclohexylnaphthalene-2,6-dicarboxamide. From both neat (?-iPP) and nucleated (?-iPP) polypropylenes compression-moulded plates were prepared using various processing conditions, and then exposed to UV-irradiation. Molecular degradation and the evolution of supermolecular structure were determined using infrared and UV spectroscopy, wide-angle X-ray scattering and differential scanning calorimetry. Different impact of UV irradiation on both ?-iPP and ?-iPP is presented. Furthermore, the effect of processing conditions on photodegradability is proved.
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