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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INCORPORATION OF SILICONES INTIO WOOD USING SUPERCRITICAL CO2
Wood samples have been impregnated with silicones and subsequently crosslinked in-situ by utilizing supercritical CO2 as a solvent and transport medium. These wood-silicone composites have been exposed to controlled thermo-oxidative conditions under load to determine their time to failure. The time to failure of wood samples has been found to be related to temperature through an Arrhenius type relationship. The addition of silicone to wood significantly increases time to failure suggesting that the silicone is acting as a reinforcing scaffold during the thermal degradation of wood.
COMPLIMENTARY FAILURE ANALYSIS METHODS AND THEIR APPLICATION TO PLASTIC PIPE
A variety of methods can be employed to characterize failure modes of plastics and identify contributing factors. By combining visual and microscopic examination with chemical analysis, the reasons for ductile, brittle, or progressive failure may be determined. This paper provides a comparative analysis based on fractography and spectroscopic analysis of chlorinated polyvinyl chloride (CPVC) pipe samples that failed due to chemical exposure. Chemical degradation and environmental stress cracking failure modes are explored using optical microscopy, scanning electron microscopy, and FTIR.
EFFECT OF INCORPORATION OF DEVULCANIZED RUBBER ON THE PROPERTIES OF A VIRGIN TIRE COMPOUND
In this work, devulcanized rubber obtained from a thermo-mechanical devulcanization process with supercritical carbon dioxide was utilized in a virgin tire compound in order to lower the material cost. Different content of devulcanized rubber from 10 phr to 30 phr was used as part of the rubber in an actual virgin tire compound. Curing characteristics, Mooney viscosity, tensile strength, tear strength, elongation at break, and hardness of different samples were measured in order to evaluate the impact of incorporation of devulcanized rubber in a virgin tire compound. The results show that up to 30 phr devulcanized rubber can be used in a virgin tire compound without any significant deteroriation in compound properties.
PROCESSING AND CHARACTERIZATION OF PEEK/MWNT NANOCOMPOSITES PREPARED BY HIGH POWER ULTRASONIC WAVES
A single screw extruder having ultrasonic barrel attachment was used to manufacture polyetheretherketone (PEEK) - multi walled carbon nanotubes (MWNT) nanocomposites with enhanced dispersion of carbon nanotubes (CNTs) in polymer matrix. The effect of ultrasonic amplitude and CNTs loading on die pressure, electrical conductivity, rheological, morphological and mechanical properties of PEEK filled with 1-10 wt% MWNT was studied. The die pressure was observed to decrease with the increase of ultrasonic amplitude and increased with the increase of CNTs loading. The electrical percolation threshold was found to be between 1 and 2 wt% loading of CNTs.
PETI-330 / MWNT NANOCOMPOSITES COMPOUNDED BY ULTRASONICALLY ASSISTED EXTRUSION
A continuous, commercially viable method for the dispersion of multi walled carbon nanotubes (MWNTs) in polymer matrices using an ultrasonically assisted twin screw extruder has been studied. The effects of ultrasound on die pressure, power consumption, rheological, morphological, mechanical and electrical properties in PETI-330 nanocomposites filled with 0-5 wt. % MWNTs have been evaluated. Ultrasonically treated nanocomposites show increased viscosity with a slight improvement in mechanical properties at various loadings and ultrasonic treatment. An electrical percolation of less than 0.5 wt. % was observed.
A STUDY OF PROCESSING INDUCED PART FAILURES
Of the four pillars required for the successful development of a plastic part; material selection part design processing and service environment processing is often assumed to be the most controllable. Even when the service environment has been properly defined the best design principles implemented and the appropriate material selected seemingly insignificant changes in processing can grossly and adversely affect an otherwise well developed product. This paper will explore case studies where the failure of the part can be traced directly back to improper processing and how shortcomings in processing ultimately predisposed them to premature failure.
A STUDY OF PROCESSING INDUCED PART FAILURES
Of the four pillars required for the successful development of a plastic part; material selection, part design, processing, and service environment, processing is often assumed to be the most controllable. Even when the service environment has been properly defined, the best design principles implemented, and the appropriate material selected, seemingly insignificant changes in processing can grossly and adversely affect an otherwise well developed product. This paper will explore case studies where the failure of the part can be traced directly back to improper processing and how shortcomings in processing ultimately predisposed them to premature failure.
FRACTURE BEHAVIOR STUDY OF MELT COMPOUNDED POLYCARBONATE/ALUMINA NANOCOMPOSITES
Two different molecular weight poly(styrene-maleic anhydride) (SMA) copolymers were used to treat spherical alumina nanoparticles to facilitate dispersion.The treated nanoparticles were then melt compounded with polycarbonate (PC) using a high intensity thermokinetic mixer. It was found that the low molecular weight polymer coating resulted in well dispersed nanoparticles in the nanocomposites with fairly high light transmittance. Furthermore the addition of the spherical nanoparticles improved the impact strength during brittle fracture of the resultant nanocomposites through the formation of multilevel microcracks and microcrazes induced by the nanoparticles.
EFFECT OF CONFINEMENT ON THE MECHANICAL PROPERTIES OF POLYETHYLENE OXIDE IN NANOLAYERED FILMS
Coextrusion through a series of layer multiplying elements has enabled the production of films containing tens to thousands of layers with individual layer thicknesses down to the nanoscale. Dynamic mechanical properties of nanolayered films of polyethylene oxide (PEO) against ethylene-co-acrylic acid (EAA), with layer thicknesses ranging from microns to 45 nm, were investigated. Although crystallinity and layer composition were constant, the glass transition intensity of the PEO was found to decrease dramatically with layer thickness. The application of a combined standard linear solid and the Takayanagi model suggest morphological changes, not decreased mobility of the polymer chains, are responsible.
GREEN LAMINATE COMPOSITES BASED ON POLYPROPYLENE (PP) AND FLAX FIBER
As the demand of green materials and green products are growing, the use of renewable resources and recycle materials are of great attraction. Natural fiber composites have been extensively studied during the last ten years. However, the main focuses were laminate thermoset composites and extrusion/injection composite products. New approach in fabricating thermoplastic composite parts and composite formulation with flax fiber at low cost has been developed to reduce energy consumption and improve the mechanical performance. The laminate composites were prepared by compression moulding. The results demonstrate that the formulation and the fiber treatment play important roles to the performances of the composites.
UV-CURING OF ACRYLATE THIN FILMS ON PARTICLULATES THROUGH FREE RADICAL POLYMERIZATION MECHANISM
The UV-curing of ultra-thin films of acrylate monomers on Al2O3 particles has been studied by using photo-differential scanning calorimetry (photo-DSC). This fundamental study is necessitated by the need to optimize the UV-curing of coated particulates in air-driven fluidized beds. The effects of chemical structures of monomers thickness of the films type of initiators and the presence of oxygen on the curing were investigated.Results show that the photo-polymerization of the ultrathin films on the particles is much more sensitive to oxygen poisoning than the thick films on flat surfaces and the conversions of monomers greatly depend on the types of monomers and initiators used. Esacure 1001M a sulfurcontaining benzophenone has been used together with 2- ethylhexyl-4-dimethylamino benzoate (Esacure EHA) as the initiation system to reduce the oxygen poisoning effect.
GET GREEN WITHOUT PAINT: MOLDED-IN-METALLIC ENGINEERING RESINS FOR APPEARANCE APPLICATIONS
Trends in styling continue to include metallic accents traditionally coming from paints and chrome plating. While paint and plating allow designers to achieve this desired look, both processes come with relatively high cost and are not environmentally friendly. VOCs, chemical disposal and no potential to recycle once the part is painted or plated are environmental concerns. New engineering resins have been developed which eliminate the need for painting and can achieve the desired appearance right out of the mold. This talk explores these resins as a way to get green: both environmentally and with lower cost.
A NOVEL TECHNIQUE TO DETECT SMALL MOLECULES OF LOW CONCENTRATION IN POLYMER BLENDS BY RUO4 STAINING
The presence and distribution of a trace amount of small molecules which can be the by-product from slight degradation of blend components during processing or a residual reagent added in reactive processing are valuable information in polymer blends.However it is often difficult to discern these substances using normal methods. Low concentrations of butannaldehyde in PC/PBT blends and free residual amine in TPU/PO blends are detected using a RuO4 staining technique under a scanning electron microscope.Fine grains which are formed by the reaction of RuO4 with them are observed both on the surface and in the bulk of the two polymer blends after the staining.
DEPENDENCY OF LPP FOAMING BEHAVIOR ON FOAM COMPOSITION AND PROCESSING PARAMETERS
In this work, the dependency of linear polypropylene (LPP) (MFI of 18 g/10min) foaming behavior on nanoclay addition and various processing parameters were explored. Because of the low cost of LPP, there is a high industrial interest in this approach. In our work, two processing methods in a twin screw extruder were utilized to see the influence of nanoclays dispersion within the polymer. A single screw extruder was used for foaming in a range of temperatures and Supercritical CO2 was used as the blowing agent. X-Ray diffraction, SEM, and density measurements were utilized to explore the nanoclaysƒ?? exfoliation, cell density, and expansion ratio, respectively.
MORPHOLOGICAL ASPECTS OF POLYPROPYLENE/CLAY NANOCOMPOSITES MATERIALS
Polypropylene clay nanocomposites were injection-molded using two different coupling agents based on maleic anhydride-grafted polypropylene (MAgPP) and two clay loadings. The morphological aspects of these materials were studied by depth profiling. Molecular chain and clay orientations were characterized using attenuated total reflectance-infrared analysis (ATR-FTIR) and transmission electron microscopy (TEM). Both clay platelets and PP molecular chain orientations were found to decrease from the surface toward the core of the injectionƒ??molded specimens. Clay intercalation, characterized by both complementary X-ray diffraction (XRD) and TEM, was found to be significantly influenced by the characteristics of the coupling agent used to optimize properties of the nanocomposites. The use of low molecular weight (Mw) maleic anhydride grafted PP (MAgPP) led to a uniform intercalation but with no further exfoliation. The use of higher Mw MAgPP led to a heterogeneous intercalation with some signs of exfoliation. The crystallization behavior of polypropylene (PP) clay nanocomposites studied by differential scanning calorimetry (DSC) showed an increase of the level of crystallinity from the surface to the core of the specimens; these results were also confirmed by scanning electron microscopy (SEM).
NEW TECHNOLOGICAL DEVELOPMENTS WITH PEBAX®
Poly ether-b-amide thermoplastic elastomers (Pebax thermoplastic elastomer*) provide a unique combination of physical chemical and processing properties. This unique combination of properties can be attributed to their chemical structure which consists of rigid polyamide segments acting as physical crosslinks and flexible polyether segments having a glass transition temperature well below room temperature (-60?øC). By selectively altering the structure and molecular weight of the polyamide and polyether segments it is possible to achieve desired properties exclusive to its respective stoichiometry and block length. It is this relationship between the polyamide and polyether phases that give its elastomeric property yielding high extensibility and recovery.The desired properties which make Pebax thermoplastic elastomer so extraordinary include exceptionally low hysteresis which results in good fatigue resistance low heat build up and good retention of properties. Other properties exclusive to Pebax thermoplastic elastomer include a low density (1.01 g/cm3) hydrophobic / hydrophilic nature depending upon monomer composition no yellowing and excellent UV resistance. What makes Pebax thermoplastic elastomer so attractive is the fact that it can be applied to nearly all industries. Due to the versatility of the physical properties of Pebax thermoplastic elastomer it is no surprise that Pebax thermoplastic elastomer is encountered in a number of applications. New technological developments with Pebax?? thermoplastic elastomer include breathable film applications for the housing and apparel industry due to excellent permeability to moisture vapor while remaining waterproof and offering an excellent barrier layer to bacteria. Additional technological developments include Pebax?? thermoplastic elastomer for durable nonwoven elastic applications due to its ability to be extruded by both melt blown and spunbond technologies. Impact modification of Pebax??
A STUDY ON THE USE OF CROSS SECTIONING OF COMPLETE PARTS AND ASSEMBLIES AS A FAILURE ANALYSIS TOOL
Of the many tools available to the professional failure analyst, ranging from compositional analysis to visual and microscopic examination, a commonly underutilized tool is examination of the failed part using stereomicroscopy of mounted cross sections. Although transmission light microscopy can be utilized for examination of the crystalline structure in thin specimens, this paper will instead focus on the use of cross sectional examination of entire parts and assemblies. This will include an overview of the sample preparation method and several examples of its use including: characterization of plating failures, detection and re-creation of leak paths, qualitative assessment of filler material distribution, and knit line integrity.
STUDY ON STEAM CHEST MOLDING PROCESS FOR EPP BEAD FOAM
This paper deals with the basic principles and procedures of the steam chest molding process for expanded polypropylene (EPP) bead foam. Steam chest molding is an integral process for EPP technology. However, little research has been carried out regarding the processing condition of steam chest molding. The characteristics of EPP foam are energy absorption, multiple impact protection, lightweight, structural strength and durability. In this study, the steam pressure in the steam chest molding was varied to find the optimum condition for manufacturing EPP foam. Moreover, annealing after EPP foam molding was put into practice to prevent the shrinkage of the steam-molded product. It was possible to verify the mechanism of foam shrinkage by observing the weight change with time at different annealing temperatures. A tensile test and scanning electron microscopy (SEM) analysis were also executed to support these experimental results. The dimensional stability was investigated for each molded product from different steam pressures.
EFFECTS OF EXTRUSION SYSTEM SCALE ON THE EXPANSION OF POLYSTYRENE FOAMS BLOWN WITH CARBON DIOXIDE
This paper presents the effects of the blowing agent content on the volume expansion of extruded polystyrene foams blown with CO2. Both lab-scale and pilot-scale extrusion systems were used to investigate the effects of extrusion equipment scales on the expansion ratio. Experimental results reveal that there was no apparent relationship between the expansion ratio of the PS foam sheets and the scale of extrusion systems. It was established that the degree of foam expansion is strongly affected by certain processing conditions, including processing temperature, pressure-drop rate, and CO2 content.
THE EFFECT OF VISCOSITY CHANGE ON FLOW LENGTH AND CELL MORPHOLOGY IN MICROCELLULAR FOAM INJECTION MOLDING
Viscosity change in polymer and gas mixtures is important in designing dies or molds because of its impact on the quality of the microcellular foaming product. In developing a continuous process for microcellular foams, very little attention has been directed towards researching the viscosity change that occurs when gas is injected into the polymer and its effect on cell morphology despite its importance. The purpose of this paper is to provide the basic data required to determine the processing condition by measuring viscosity changes against the gas injection rates of the blowing agent, and to verify the influence of viscosity change on the cell morphology of the samples during the injection molding process.
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