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
SONOPLAST NEW PROCESS AND MACHINERY FOR MICROPARTS MOLDING BASED ON ULTRASOUND EXCITATION
Injection molding although widely extended as one of the main replication technologies has shown important limitations when applied to the manufacture of plastic parts in the micro and mini scale. The present work describes a new moulding process based on the fusion ofthat has been thermoplastics materials via ultrasounds developed in the Sonoplast European project. First experimental achievements led to an innovative concept of mould and ultrasound moulding machine for the production of plastic parts (micro and mini). In addition the molding process management is simplified and directed by few machine parameters differing from conventional injection molding. The ultrasound molding process is extremely fast and with reduced filling pressures achieves a very good reproduction of the mould micro details. Besides it has been possible to obtain reductions about 50% on sprue volumes (around 0,16 g of plastic per shot) comparing with a conventional microinjection machine. Moreover, process energy consumption and power requirements are between 500 and 1200J and 200 and 500W, respectively. Finally, rheological analysis showed that no noticeable degradation process occurred after processing; equally, tensile testing gave better mechanical performance retention, comparing with traditional microinjection processes.
DEVELOPMENT OF OXYGEN SCAVENGING BIOCOMPOSITES BASED ON PLA AND OXYGEN SCAVENGING NANOCLAYS FOR PACKAGING APPLICATIONS
A new commercial iron-based oxygen scavenging montmorillonite clay (MMT-Fe), was analyzed for its oxygen scavenging capacity. In a subsequent step, it was incorporated by solution casting into PLA to obtain a brown colored nanocomposite sheet with significant oxygen scavenging properties. Since PLA is known to exhibit shortages in barrier properties to gases, which conventional existing nanoclay formulations cannot overcome, the potential of combining the passive barrier properties of nanoclays with a novel functionalization capable of scavenge oxygen from the packaging headspace shows strong potential in high barrier packaging applications of oxygen sensitive products.
MORPHOLOGY AND BARRIER PROPERTIES OF SOLVENT CAST NANOCOMPOSITES OF POLYLACTIC ACID WITH CELLULOSE NANOWHISKERS DERIVED FROM ALPHA PURIFIED MICROFIBERS
PLA nanobiocomposite films containing cellulose nanowhiskers (CNW) were obtained by solution casting. The cellulose nanowhiskers, prepared by acid hydrolysis of microfibers of highly alpha purified cellulose, consisted of nanofibers of typically 60 to 160 nm in length and 10 to 20 nm in thickness. The nanocomposites were prepared by incorporating 1, 2, 3 and 5 wt.-% of the CNW into the PLA matrix. The morphology and mass transport properties of the films were investigated by SEM, TEM, AFM, optical microscopy, OTR and WVTR.
CONTACT ANALYSIS OF THE SOLID POLYPROPYLENE ƒ?? AISI P20 MOLD STEEL TRIBOSYSTEM
The contact between solid polypropylene (PP) and AISI P20 steel with 38 HRC was studied for several average roughness of the steelƒ??s surface. An instrumented pin-on-disk tribometer was used to measure the friction force during contact. The conditions used allow approaching to limited studied PP ƒ?? AISI P20 steel tribosystem. A high influence of adhesive wear was observed and related to high local temperatures in the PP surface. The aim of this research was to determine the contact characteristics between solid PP and AISI P20 steel during dry sliding in a pin-on-disk system. This experimental study brings valuable results about the interaction between surfaces types of contact and friction and wear phenomena.
CONTACT ANALYSIS OF THE SOLID POLYPROPYLENE – AISI P20 MOLD
STEEL TRIBOSYSTEM
The contact between solid polypropylene (PP) and
AISI P20 steel with 38 HRC was studied for several
average roughness of the steel’s surface. An instrumented
pin-on-disk tribometer was used to measure the friction
force during contact. The conditions used allow
approaching to limited studied PP – AISI P20 steel
tribosystem. A high influence of adhesive wear was
observed and related to high local temperatures in the PP
surface. The aim of this research was to determine the
contact characteristics between solid PP and AISI P20
steel during dry sliding in a pin-on-disk system. This
experimental study brings valuable results about the
interaction between surfaces, types of contact and friction
and wear phenomena.
RELAXATION BEHAVIORS AND CLAY DISPERSION IN MALEATED POLYPROPYLENE NANOCOMPOSITES
The dynamic and dielectric relaxations of of maleic anhydride grafted polypropylene (PPgMA) and its clay filled nanocomposites with different degree of clay exfoliation have been investigated. Fully and partially exfoliated samples were prepared through powered sonication and melt blend respectively. Ourresults indicated that both mechanical and relaxations can be identified with dynamic mechnaical analysis. Only a single relaxation process due to interfacial polarization was observed in broadband dielectric measurements. Dielectric dispersion parameters including dielectric strength and peak relaxation frequency were identified and appeared sensitive to the degree of clay exfoliation.
SURFACE MODIFICATION OF INKS, COATINGS AND ADHESIVES – THE INTERFACIAL EFFECTS
It is well-documented that plastics surface modification techniques can greatly improve the acceptance of a wide variety of coatings, adhesives and inks for improved decoration, painting and adhesive assembly. By increasing the hydrophilic characteristics and surface-free energy of plastics, bond strengths can be improved dramatically. It is theorized that interlayer adhesion between decorating and assembly formulations can also be improved by applying atmospheric plasma surface modification techniques. This study examines experimental data which relate correlations between surface modification and interlayer adhesions of inks, coatings and adhesives.
APPLICATIONS FOR STRUCTURED LIGHT SCANNING IN PLASTIC PRODUCT DEVELOPMENT
The continued evolution of non-contact scanning methods has led to the development of highly effective tools for investigative metrology. Structured white light scanning technologies in particular can now generate a wealth of data for identifying and quantifying nearly all aspects of part geometry. When applied to the development process for plastic parts and products, such tools can be invaluable in evaluating design, material, tooling, and process related issues. This paper recounts the implementation of structured light scanning, automation, and data processes at Motorola, and reviews its impact on a variety of applications.
EFFECT OF HYBRIDIZATION ON THE MECHANICAL PROPERTY OF INJECTION MOLDED HEMP/GLASS COMPOSITES
In this study, long fiber pellets were used to make hemp/glass hybrid reinforced polypropylene (PP) composites by injection molding process. The mechanical property and the fracture behavior of both welded and un-welded dumbbell specimens were investigated in tensile test. It is found that in hybrid composites, the optimum hybrid ratio exists for both high tensile modulus and tensile strength. The interface property between fibers and PP were discussed based on the observation and weld strength. Last, rule of mixture was used to calculate the practical modules and strength of both hemp and glass fiber in injection molded composites from the monotonic specimens. Then the calculated results were applied again into rule of mixture for hybrid composite which involved both glass and hemp fiber. It is found that the prediction results are much closed to the experimental data.
A COMPARISON OF SEVEN TRANSFER METHODS FOR VELOCITY TO PRESSURE SWITCHOVER
Molding processes typically utilize a velocity controlled filling stage followed by a pressure controlled packing stage. The short term and long term effectiveness of seven different switchover methods are considered including: 1) ram position 2) injection time 3) machine pressure 4) nozzle pressure 5) runner pressure near the sprue 6) cavity pressure near the gate and 7) cavity temperature at the end of flow. The results indicated that the machine controlled switchover methods (ram position injection time and machine pressure) had a lower short term variation in the quality of the molded parts but the other switchover methods were more robust with respect to rejecting long term process variation.
A COMPARISON OF SEVEN TRANSFER METHODS
FOR VELOCITY TO PRESSURE SWITCHOVER
Molding processes typically utilize a velocity controlled
filling stage followed by a pressure controlled packing
stage. The short term and long term effectiveness of seven
different switchover methods are considered, including: 1)
ram position, 2) injection time, 3) machine pressure, 4)
nozzle pressure, 5) runner pressure near the sprue, 6)
cavity pressure near the gate, and 7) cavity temperature at
the end of flow. The results indicated that the machine
controlled switchover methods (ram position, injection
time, and machine pressure) had a lower short term
variation in the quality of the molded parts, but the other
switchover methods were more robust with respect to
rejecting long term process variation.
EFFECT OF ORGANOCLAY ON THE MECHANICAL PROPERTIES OF MICROCELLULAR INJECTION MOLDED TPO-CLAY NANOCOMPOSIT ES
Thermoplastic olefin elastomers (TPO)/montmorillonite (MMT) nanocomposites prepared by kneader and melt compounding methods were used in this study. The organoclay TPO nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclay content and preparation methods on the mechanical/thermal properties was investigated. The results show that the mechanical properties increase as the clay content increased for both the kneader and melt compounding processes. The foaming by kneader had better cell density than that of melt compounding, and cell size decreased as the clay loading increased. The addition of MMT also improved the thermal stability of the TPO/clay nanocomposites. The XRD results show that the nanocomposites having an intercalated layered structure.
INJECTION MOLDING OF HIGH-PERFORMANCE HYBRID COMPOSITES IN SERIES-PRODUCTION
In-mold forming (IMF) is a new injection molding
technique to produce high-performance light-weight parts.
Unlike the conventional process the novel molding technology
is particularly suitable for mass production because
its cycle times are short cost-effective and efficient.
In this process a pre-heated fiber-reinforced thermoplastic
sheet is formed in the injection molding machine followed
by instantaneous overmolding thus forming short
glass fiber reinforced thermoplastic ribs to reinforce the
structure. To show the manufacturing procedure as well as
the new molding devices required the system was implemented
for the example of a steering column connection.
INJECTION MOLDING OF HIGH-PERFORMANCE HYBRID COMPOSITES IN SERIES-PRODUCTION
In-mold forming (IMF) is a new injection molding technique to produce high-performance light-weight parts.Unlike the conventional process, the novel molding technology is particularly suitable for mass production, because its cycle times are short, cost-effective and efficient.In this process, a pre-heated fiber-reinforced thermoplastic sheet is formed in the injection molding machine, followed by instantaneous overmolding, thus forming short glass fiber reinforced thermoplastic ribs to reinforce the structure. To show the manufacturing procedure as well as the new molding devices required, the system was implemented for the example of a steering column connection.
PREDICTION OF MASS TRANSPORT OF SOLVENT / POLYMER SYSTEMS IN HIGH VOLUME KNEADER REACTORS AT FINITE SOLVENT CONCENTRATIONS
Kneader reactors are used for combined unitary processing in the polymer industry for devolatilization, compounding or polymerization. In the past, mass transport prediction for devolatilization operations in kneader reactors did not match experimental results, when diffusion was assumed as sole driving force. It was detected that there is an additional concentration and temperature dependent driving force that triggers enhanced transport at finite solvent concentrations by orders of magnitude. The author suggests that the underlying root cause is likely micro bubble formation within the polymer melt. An attempt to model this additional mass transport mechanism is presented.
NANOSTRUCTURE CONTROL FOR TUNING THE GLASS TRANSITION TEMPERATURE OF POLYSTYRENE BY 100 K: BLENDS AND MULTILAYER FILMS
The glass transition temperature (Tg) of an ultrathin polystyrene (PS) layer within a multilayer film geometry was analyzed by using a fluorescence technique; the Tgs of PS layers were tuned over 100 K by varying the species and thickness of the neighboring polymer layer. Similar Tg perturbations were observed for the first time in poly(styrene-block-4-vinylpyridine)/poly(4-vinylpyridine) (P4VP) blends. The Tg of the styrene block nanodomains increased by ~40 K by reducing the styrene block composition within the blends. This study suggests a novel route to create new material properties controlled by the polymer type and nanoconfined dimension in multilayer films and nanostructured blends.
FLAME RETARDANT PC/ABS BLENDS FOR NOVEL LOW GLOSS MEDICAL APPLICATIONS
Flame retardant (FR) PC/ABS blends find
applications in the medical housings market owing
to their superior processability and a fine balance
between the primary requirements of flammability
performance mechanical properties and chemical
resistance to hospital cleaners. In recent times low
part-surface gloss is emerging as an important
requirement for such applications. This manuscript
showcases a new chlorine-bromine free FR PC/ABS
blend which meets these demanding requirements
for extrusion and thermoforming applications.
FLAME RETARDANT PC/ABS BLENDS FOR NOVEL LOW GLOSS MEDICAL APPLICATIONS
Flame retardant (FR) PC/ABS blends find applications in the medical housings market owing to their superior processability and a fine balance between the primary requirements of flammability performance, mechanical properties and chemical resistance to hospital cleaners. In recent times, low part-surface gloss is emerging as an important requirement for such applications. This manuscript showcases a new chlorine-bromine free FR PC/ABS blend which meets these demanding requirements for extrusion and thermoforming applications.
AN INLINE MEASUREMENT SYSTEM FOR MICRO-FEATURES AND STRUCTURED SURFACES
A system offering two different measurement methods for 3-dimensional evaluation of micromoulded surface features within a moulding process has been designed, manufactured and tested. The system adopts two methods for height measurement and subsequent 3D surface reconstruction. The first method, for feature sizes in the region 10?¬m to 2mm and non-optical surfaces, uses a local contrast technique to calculate when regions of the component come into focus and calculates surface heights accordingly. The second method, for the measurement of optically smooth, featureless surfaces, uses White Light Interferometry techniques to measure surface data. Both methods are seamlessly integrated into the system and require nothing more than a lens change to switch between the two.
HIGH SPEED THERMAL IMAGING OF MICROMOULDING
Micromoulding is a thermally dominated process.
Due to manufactured parts having high surface area to
volume ratios extremely high cooling rates are achieved.
Thermal measurements using surface mounted
thermocouples at comparable rates are impractical due to
their relatively high response times. To address this issue
an AGA 782 SW thermal imaging camera has been
modified such that it runs in a linescan mode and data are
collected using a high speed digitiser to allow capture
rates of 2500 lines per second. The rapid cooling of a
range of components and materials have been recorded
and the superheating of air traps within the component
have been observed.
Due to manufactured parts having high surface area to
volume ratios extremely high cooling rates are achieved.
Thermal measurements using surface mounted
thermocouples at comparable rates are impractical due to
their relatively high response times. To address this issue
an AGA 782 SW thermal imaging camera has been
modified such that it runs in a linescan mode and data are
collected using a high speed digitiser to allow capture
rates of 2500 lines per second. The rapid cooling of a
range of components and materials have been recorded
and the superheating of air traps within the component
have been observed.
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