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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Adaptive GPC Control of Barrel Temperatures in Injection Molding
Injection molding barrel temperatures have high interaction and slow responses. The classical proportionalintegral-derivative (PID) control has difficulties to control for them accurately. An adaptive multi-input-multi-output (MIMO) generalized predictive control (GPC) scheme is developed, implemented and tested for barrel temperatures control of a reciprocating-screw injection molding machine. Experimental results illustrate GPC superiority over the traditional PID control.
Effect of Low Density Polyethylene on Polystyrene Foam
This work examines the foam density of polystyrene (PS) blended with low density polyethylene (LDPE) at various ratios and the thermal conductivity of vacuum insulation panels (VIPs) using PS/PE with filers foams as core materials. The experimental results indicate LDPE strongly influences the foam density of PS/PE foam and the content of open-cell in PS/PE with fillers foam. A higher content of open-cells in PS/PE with fillers foam can lead to a lower thermal conductivity of VIP.
Mechanical Properties of Textile-Inserted PP/PP Knitted Composites
Composites consisting of the same material with different reinforcement and matrix shapes, such as fibre and matrix phases, can create high interfacial strength. This paper concentrates on the experimental investigation of all-polypropylene single phase composites. It is interestingly noteworthy that reinforced homo PP composites exhibited superior energy absorption capability when compared with their virgin counterpart for both static and dynamic impact test.
Viscoplastic Behaviour of Ultra-High Molecular Weight Polyethylene
We have carried out experiments on UHMWPE in uniaxial compression in which we have measured the stress-strain and stress relaxation behaviour, covering a wide range of strains and strain rates. A constitutive model that makes use of Eyring processes has been developed and implemented numerically. This model can represent rate-dependent stress – strain behaviour. We have derived a set of values for the model parameters such that it gives a good representation of the observations.
Computer Simulation of 3D Filling and Packing Process in Injection Molding
This paper presents a true three-dimensional numerical simulation of the mold filling and packing in injection-molded part. The segregated finite element method and control volume finite element are combined with VOF method to solve the flow/temperature field and to track the melt front advancement during the process. The iterative solver (SOR) was employed for the solution of the equations. Several numerical examples are compared with Hele-Shaw approximation.
Radio Frequency Welding of Thermoplastic Vulcanizates
Radio Frequency (RF) welding, also known as High Frequency (HF) welding, is often a preferred means of fabricating products made of polar thermoplastic materials. Thermoplastic materials with low dielectric loss factors, such as thermoplastic vulcanizates (TPVs) have presented a challenge to RF welding. Modification of traditional RF welding equipment has been studied to characterize successful RF welding of TPVs with varying rubber to plastic ratios.
An Examination into the Effects of a Fluoropolymer Additive in Nylon 6/6 Neat Injection Molding Resins
A fluoropolymer additive can be used to aid in the processability of resins and to improve some physical properties of the final part. The changes in processability and physical properties are explored. This study examines the effects of the base resin with a loading of fluoropolymer at 0.00% , 0.10%, 0.25%, and 0.50%. Several experiments were run to determine the effects of the fluoropolymer on processing and physical properties.
The Evolution of Color Difference Equations
A comparison of the evolution of different color difference equations, and which ones are commonly used in plastic color measurement today.
Modeling of Substituted Biphenyl Compounds
We study the effect of the length of an alkane bridge on the equilibrium geometry of biphenyl. We rely on DF theory within the 6-31G* ab-initio framework to determine local energy minima and geometries. We discover that the effect of the bridge length is decidedly nonlinear.
Crush-Behavior of GMT-Products
Compression tests were carried out on Glass Mat Reinforced Thermoplastics (GMT) panels applying three ratios for thickness over width. Some panels showed a typical ductile splaying collapse mode with gross plasticity. The specific energy absorption of these panels was very high, and even higher than was found in literature for crush cones of this material. Aim is to formulate design rules for products that are composed of flat plane elements and are loaded on impact.
The Effect of Cooling Regime on the Thermal, Mechanical and Morphological Properties of Polyolefins
The effect of cooling rates (2-300degC/min) on the crystallinity, morphology and tensile properties of a selection of polyethylene and polypropylene resins was investigated using conventional and high speed DSC. Increasing cooling rate caused a decrease in percentage crystallinity. Mechanical analysis and polarised light microscopy showed related reductions in tensile modulus and strength and crystallite configuration.
Standardization of High Strain Rate Tensile Testing of Polymers
The results of an interlaboratory test program conducted to assess the precision of the Practice Guide for High Strain Rate Testing of Polymers are summarized. Five polymers, HDPE, 30% short glass fiber-filled PA, PC/ABS, 40% long glass fiber-filled PP, and TPO, were tested at nominal plastic strain rates of 40/s and 400/s. The test results were used to generate inter and intralaboratory variability statistics that were incorporated into a precision statement for the Practice Guide.
The Effect of Solar Energy on Decorative Woodgrain Foils Laminated on UPVC Profiles
Decorative woodgrain foils are important in the aesthetic appearance of UPVC profiles in the conservatory industry. Dark colours tend to absorb solar energy which causes distortion when reaching a critical temperature. This research has investigated three different foils subjected to simulated solar energy when placed on UPVC profiles using a specially designed test rig. This equipment failed to give results correlating to outdoor experience, therefore the test will be needed to be modified to be useful.
Chain Extended/Branched PET-Organoclay Nanocomposites
The effects of chain extension and branching on the properties of nanocomposites produced from recycled poly (ethylene-terephthalate) and organically modified clay were investigated. As the chain extension/branching agent, maleic anhydride (MA) and pyromellitic dianhydride (PMDA) were used. Both MA and PMDA improved the mechanical properties of the nanocomposite owing to the branching and chain extending effects that increase the molecular weight. However, PMDA gave better results at lower content.
The Effect of Thermal History Development on Crystalline Medical Grade TPUs
In this study a range of polyurethanes were extruded in sheet form and cooled at various chill roll temperatures. Crystallinity of the samples was determined using DSC and the results showed significant changes in morphology of the hard and soft segment phases, which in turn had a significant effect on the mechanical properties and phase transitional properties of the individual resins.
Rheological, Mechanical and Thermal Behaviour of Radiopaque Filled Polymers
This work studied the effect of three radiopaque fillers (barium sulphate, bismuth trioxide and tungsten metal) on the rheological, mechanical and thermal properties of a range of medical grade polyurethanes and polyvinylchlorides. The results showed significant changes in the melt viscosity, mechanical properties and phase transitions (Tg and log E’) with different filler type.
Chemical Structure Effects on the Performance of TPUs
This work studied the effect of polyurethane chemical structure (i.e. polyester or polyether soft segments) on the rheological, mechanical and thermal properties of four commercial medical grade polyurethanes of similar Shore hardness. The results showed significant differences in melt viscosity, tensile properties and phase transition temperatures (tan ?) with particular polyurethane chemical structure.
Foams Extruded from Polystyrene / Thermoplastic Starch Blends
This work aims at the development of foams from Polystyrene (PS)/Thermoplastic Starch (TPS) blends. The gelatinization and plasticization of the starch granules, the TPS/PS melt blending and the HFC134a blowing agent dissolution was carried out in a twin-screw extrusion process. The viscosity of the blends, with and without the blowing agent, was measured on-line. The obtained foam morphology, density and open-cell fraction are discussed.
CPVC in Rigid PVC Profile Formulations
10-50% of CPVC was mixed with UPVC formulations used in extruded profiles for conservatory roofing applications. The shear viscosity, mechanical properties and dynamic mechanical thermal properties of various formulations were shown to be dependent to the CPVC concentration. A blend 40% of CPVC and 60% UPVC exhibited a great increase in mechanical properties.
Impact Stregnth as a Function of Foam Density
Structural high density polyethylene foam is commonly used in many household applications. Is has been accepted by the industry that foaming creates internal space in an injection molded article and therefore allows the part to absorb impacts without initiating cracks. This paper seeks to determine the relationship between the density of a structurally foam molded article and the impact strength.
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