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
INVESTIGATION INTO A HIGH OUTPUT POLYPROPYLENE SCREW AND ITS MIXING MECHANISM
It is known, industry wide, that polypropylene (PP) resins plasticate at reduced rates compared to other olefins. While many causes have been suggested for this problem, a solution was not. A simple, spiral fluted extensional mixer (SFEM) was first introduced for the single screw extruder (SSE) for its superior compounding. A variation, the Elongator II, hereafter SFEM II, was tested against a control screw for output. A 100% increase in output was found over a conventional screwƒ?? more than making up for PPƒ??s historically low rate.Because the SFEM series is noted for its ability to compound like a twin, we investigated mixing on the SFEM II. The investigation compares the flow to a simple computer model. A color concentrate of just 0.5% was used with frozen pullouts or carcasses showing the mixing during operation. The extrudate is examined and, even when magnified to 100X, does not show striation lines.
A DISCUSSION ON PREVENTION OF PLASTIC PRODUCT FAILURES
This paper attempts to show through case studies how plastic product failures could be prevented. Failures of plastic products manufactured from HDPE, PBT, and glass-filled nylon material are discussed. In each case study, the root-cause of the plastic product failure has been identified through a failure analysis investigation. The corrective action during the material selection process, the part design process, or the manufacturing process that would have prevented the failure has been suggested. The discussion of these case studies will enhance the understanding of the common errors occurring during the plastic product cycle. This paper should foster further discussion and reporting with focus on prevention of plastic product failures.
CHARACTERIZATION OF THE MICROSTRUCTURE OF POLY (HYDROXY BUTANOIC ACID) COPOLYMERS DURING THEIR POST-FABRICATION ANNEALING AT ROOM TEMPERATURE
The mechanical properties of bio-based, biodegradable poly (hydroxy butanoic acid) or PHB copolymers are known to change considerably over a period of time after their parts are fabricated. This study will focus on the changes in semi-crystalline morphology during this aging process. The semi-crystalline morphology is characterized using the three-phase model (crystalline, mobile amorphous and rigid amorphous phases) and through a variety of experimental probes including thermal analysis, refractometry, x-ray diffraction and solid-state NMR.
AN IN SITU STRUCTURING RHEOMETER BASED ON CHAOTIC ADVECTION
An in situ structuring rheometer (ISSR) has been developed that allows simultaneous controlled formation of structure in polymer blends and composites and measurements of rheological properties. Multi-layer, interpenetrating, and platelet polymer blend morphologies are examples of structure types producible. Networks among solid particles and dispersions can also be formed.The ISSR is modular for installation into existing rheometer platforms. In situ structuring in the melt occurs by chaotic advection which recursively stretches and folds melt domains. Characteristic structure sizes in the melt can reduce to nano-scales so the ISSR also has application to nanocomposites.
PHYSICAL AND MECHANICAL PROPERTIES OF NEW HIGH-FLOW POLYCARBONATE COPOLYMERS
A new range of polycarbonate copolymers derived from bisphenol-A (BPA) and specific bio-sourced monomer derived from castor bean oil is presented. These copolymers, designated LEXAN* HFD resins, offer an improved melt flow and ductility balance compared to standard polycarbonate yet offer similar high optical clarity and light transmission properties. Lower temperature processing capability, longer injection molding flow lengths, improved low temperature ductility, and superior mold release performance are all advantages for these new copolymers versus a standard polycarbonate material. Glass fiber-filled formulations of the HFD copolymer show comparable mechanical and impact properties compared to glass-filled polycarbonate materials but show nearly 50% higher surface gloss in injection molded plaques.
ADHESION OF ELASTOMERIC COPOLYMERS TO POLYOLEFINS
The effectiveness of elastomeric copolymers as adhesives for polypropylene and polyethylene was studied using coextruded microlayered tapes. The olefinic and styrenic block copolymers were the most effective adhesives of all the elastomeric copolymers used in this study and they delaminated adhesively from the polypropylene-tie-layer interface during T-peel experiments. The effect of tie-layer thickness peel temperature and peel rate on the adhesive properties were probed. Relationships between tie-layer deformation damage zone structure interfacial morphology and delamination toughness were established and a structural mechanism is provided.
APPLICATIONS OF HYPHENATED DSC-RAMAN SPECTROSCOPY TO POLYMERS
DSC is widely used to investigate phase changes of materials as their temperature is changed, or isothermally.However the information obtained is essentially quantitative as this is a univariate technique that simply measures heat flows. Vibrational spectroscopy can provide complementary information, giving insight at molecular level.into the changes accompanying thermal events or reactions. In addition the multivariate nature of Raman spectra means that it is possible to monitor simultaneous events with different spectral signatures that cannot be distinguished by DSC. A hyphenated system is described, evaluated and applied to some polymer systems
THE EFFECT OF MOLD TEMPERATURE ON THE SURFACE PHASE MORPHOLOGY OF INJECTION MOLDED THERMOPLASTIC ELASTOMERS
The surface phase morphology of thermoplastic elastomers can be affected by injection molding parameters. In this paper the influence of mold temperature on the phase morphology of SEBS triblock copolymer was studied through tapping mode atomic force microscope (AFM) and 2D-Fast Fourier Transformation (2D-FFT) analysis. It was found that more orientation was present in the materials prepared using high mold temperatures.The orientation direction of the morphologies could be predicted by computer simulation.2D-FFT analysis can be used to study the domain orientation and structure.
REINFORCING POLYPROPYLENE WITH LOW MOLECULAR WEIGHT COMPOUNDS
This study presents a new approach which involves
melt-blending a low molecular weight additive and a
polymer at a process temperature where the additive
reduces the process viscosity. Upon cooling, the additive
forms crystalline reinforcing domains. Emphasis is given
to reinforce isotactic-polypropylene (iPP) with calcium
stearate (CaSt). The changes in yield strength and
modulus suggest a synergy between the CaSt and iPP.
Addition of 10% CaSt increases the fracture energy by 5
fold without a loss in modulus and with an apparent
reduction in shear viscosity. CaSt is the only additive
commencing simultaneous improvements.
EFFECT OF MOLECULAR STRUCTURE ON HEAT SEAL PROPERTIES FOR
HIGH DENSITY POLYETHYLENE FILM
Effect of molecular structure on heat seal properties
for high density polyethylene (HDPE) film was
investigated in this study. Polyolefin is usually adopted as
a sealant material for general packaging system. Melting
temperature of the HDPE film used in this study was 126
oC. The heat seal temperature was controlled and varied at
around melting temperature of HDPE precisely. The
mechanical property of the sealed films was measured by
a T-shape peeling test. Development molecular structure
at film interface for sealing was evaluated in a wide angle
x-ray diffraction pattern and changing of molecular
orientation relaxation corresponding with the mechanical
peeling property. Thermal property was also analyzed by
a differential scanning calorimetry (DSC). The weight
fraction of melting region in heat seal process was
estimated from the DSC thermograms. We discussed that
the amount of melting region is related to the major factor
to decide peeling properties of heat sealed HDPE film.
EFFECT OF MOLECULAR STRUCTURE ON HEAT SEAL PROPERTIES FOR HIGH DENSITY POLYETHYLENE FILM
Effect of molecular structure on heat seal properties for high density polyethylene (HDPE) film was investigated in this study. Polyolefin is usually adopted as a sealant material for general packaging system. Melting temperature of the HDPE film used in this study was 126oC. The heat seal temperature was controlled and varied at around melting temperature of HDPE precisely. The mechanical property of the sealed films was measured by a T-shape peeling test. Development molecular structure at film interface for sealing was evaluated in a wide angle x-ray diffraction pattern and changing of molecular orientation relaxation corresponding with the mechanical peeling property. Thermal property was also analyzed by a differential scanning calorimetry (DSC). The weight fraction of melting region in heat seal process was estimated from the DSC thermograms. We discussed that the amount of melting region is related to the major factor to decide peeling properties of heat sealed HDPE film.
THE SCIENCE OF MARRYING TECHNOLOGIES TO PRODUCE CROSSLINKED NANOCOMPOSITES-WHY?
An attempt was made to combine two existing technologies ƒ??nanocompositesƒ? and ƒ??crosslinkingƒ?. The goal of this work was to study the combined effects of nanoclay and crosslinking on the physical properties of polyamides. Tensile and flexural properties have been studied and reported. The effect of radiation dosage level on these properties has been looked at as well.The approach was to melt blend polyamide based polymers used in the medical industry with nanoclay and a crosslinking agent. The different polyamide based polymers used were nylon 12 and a polyether-block amide copolymer. The nanoclay used was Closite from Southern clay.
NOVEL POLYPHENYLENE ETHER-POLYSILOXANE BLOCK COPOLYMER
Polyphenylene ether is an engineering thermoplastic known for its excellent water resistance, dimensional stability and inherent flame retardancy. A triblock copolymer of polyphenylene ether-polysiloxane is produced by the oxidative coupling polymerization of 2,6-xylenol and eugenol-capped polysiloxane. This method of producing the copolymer is simpler than prior methods of preparing related copolymers by linking preformed polyphenylene ether and polysiloxane blocks. This paper describes the copolymer structure and the significant improvements in key properties such as impact resistance, flame retardancy and smoke generation obtained with the copolymer as compared to the polyphenylene ether homopolymer.
RELATIONSHIP BETWEEN FILM STRUCTURE DEVELOPMENT AND
EXTRUDED FILM WIDTH IN T-DIE EXTRUDING OF
HIGH DENSITY POLYETHYLENE
Molecular structure development and the deformation
width and thickness behavior in T-die extruding of high
density polyethylene (HDPE) was studied. The extruding
through-put rate polymer material feeding rate and
winding roll temperature were fixed. The velocity of
winding roll was controlled and varied independently. The
effect of processing condition was analyzed from
molecular orientation distribution in machine direction
(MD) to transverse direction (TD) by measuring optical
retardation. To analyze crystalline structure development
behavior of HDPE film wide angle x-ray diffraction
(WAXD) pattern was also measured in TD of extruded
film. The diffraction intensity distribution on the equator
the meridian and azimuthal direction for (110) and (200)
were evaluated. We discussed major factor to control film
width and thickness. Relationship between molecular
structure development and the external form of extruded
film was studied.
RELATIONSHIP BETWEEN FILM STRUCTURE DEVELOPMENT AND EXTRUDED FILM WIDTH IN T-DIE EXTRUDING OF HIGH DENSITY POLYETHYLENE
Molecular structure development and the deformation, width and thickness behavior in T-die extruding of high density polyethylene (HDPE) was studied. The extruding through-put rate, polymer material feeding rate and winding roll temperature were fixed. The velocity of winding roll was controlled and varied independently. The effect of processing condition was analyzed from molecular orientation distribution in machine direction (MD) to transverse direction (TD) by measuring optical retardation. To analyze crystalline structure development behavior of HDPE film, wide angle x-ray diffraction (WAXD) pattern was also measured in TD of extruded film. The diffraction intensity distribution on the equator, the meridian and azimuthal direction for (110) and (200) were evaluated. We discussed major factor to control film width and thickness. Relationship between molecular structure development and the external form of extruded film was studied
EFFECT OF PREPLACED NANOPARTICLE ON THE MANUFACTURABILITY OF FIBER REINFORCED POLYMERIC COMPOSITES (FRPC)
Nanoparticles have shown the potential to improve the mechanical properties of fiber reinforced polymeric composites (FRPC). Premixing nano particulate into the resin is a common approach to add nanoparticles into FRPC. However, well dispersed nanoparticles will greatly increase the resin viscosity and filtering of the nanoparticles is difficult to avoid. To solve these problems, a new method to pre-bind the nanoparticles onto the long fibers has been developed by our group. We have previously presented results on the effect of nano particles on the preform permeability, in this paper we develop an approach to relate the overall preform permeability to the amount of nano fibers prebinded.
ANOMALOUS RHEOLOGICAL PROPERTIES FOR BINARY BLENDS OF
LINEAR POLYETHYLENE AND LONG-CHAIN BRANCHED POLYETHYLENE
The rheological properties for the binary blends composed of a linear polyethylene and a branched polyethylene (LDPE) are studied. It is found that some blends show enhanced oscillatory shear moduli than the individual pure components, suggesting that the relaxation mechanism with long characteristic time is generated in a molten state. Further, they show higher zero-shear viscosities. The drawdown force, defined as the force needed for the extension of a polymer melt from a capillary rheometer, is also evaluated to comprehend the rheological information under the elongational flows and found to be quite sensitive to the anomalous behavior. Furthermore, it is found that the blends show marked flow instability, because they have longer relaxation time than the pure components.
THE USE OF WATER CONTAINING TPO/ACTIVATED CARBON IN INJECTION MOLDING
In injection molding, cycle time and sink mark are critical factors for process economics and product quality. This work focuses on reducing cycle time and sink part by utilizing water containing polymer/activated carbon pellets. Pellets were prepared by compounding a microparticle, activated carbon (AC) via extrusion, followed by a batch process of pressurizing a small amount of water into the pellets under controlled pressure and temperature. The amount of water, packing pressure and packing time were varied in the injection molding experiment. Preliminary results showed that the cycle time could be reduced to half and part shrinkage substantially decreased at a lower packing pressure without losing mechanical properties when the water content was low (e.g. 0.3 wt %). However, too much water (e.g. 2 wt %) tended to reduce mechanical properties even though the cycle time could be further reduced. We are in the process of tailoring the process conditions for optimized results, as well as evaluating the effect of residual water on the long-term properties of molded parts.
IMPROVED MECHANICAL PROPERTIES AND PRODUCT PERFORMANCE FOR IMPACT MODIFIED POLYOXYMETHYLENE CO-POLYMERS
Ticona has developed a new family of impact modified polyoxymethylene (POM) co-polymers that demonstrate a combination of improved stiffness, impact strength, and up to a 290% increase in weld line performance compared to similar commercially available impact modified POM co-polymers. The unique properties of the new products have been achieved through the modification of the polymer backbone. The new grades provide enhanced product performance, up to 30% faster cooling time, and less mold deposit for a variety of injection molding and extrusion applications.
CHARACTERIZING LONG-TERM PERFORMANCE OF PLASTIC PIPING MATERIALS IN POTABLE WATER APPLICATIONS
Plastic piping materials confer many advantages in Potable Water applications and have enjoyed a long and successful application history. Part of that success has been the considerable research that has been conducted to develop methodologies for characterizing and ensuring service performance. A key component of accelerated methodologies is ensuring that the observed mechanisms are the same as those potentially occurring in the field. In this paper field exposed plastic piping materials from aggressive applications are examined to determine the aging mechanisms observed in end-use environments.These mechanisms are compared with those observed in accelerated testing.
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