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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Robert Slawska | Brian Dowler | Luis Lacambra, November 2011
Many producers of large technical parts are struggling
with increasing demands for short-run parts, caused by a
trend toward differentiation (more SKU’s), Just In Time
(JIT) delivery and multiple colors for consumer appeal.
With many large technical machines requiring as much as
8-12 hours of running to switch colors or materials, this is
a huge cost and profit drain on processors.
This technical paper illustrates the necessary key elements
in large part blow molding to tackle these supply chain
requirements. It discusses current limitations, and
advances in machinery design to enable fast resin and
color changes in large industrial machines.
Authors Brian Dowler | Luis Lacambra, November 2011
This technical paper illustrates the current state and
applications for multilayer containers that package food
and consumer products. The paper describes different
structures utilized in making containers for varying
applications, including demanding barrier requirements.
We also discuss how to meet requirements for food
processing systems, including hot fill, pasteurization, and
retort. Several case studies of multilayer containers
currently in the market are shown. The paper includes
pictures and diagrams and is designed to serve as an
ongoing guide for anyone tasked to determine
appropriate container manufacturing processes,
container designs, and material configurations to meet
various barrier and post-filling requirements.
Mariajosé Pineda Manzano | Joel Bohórquez | Agustín Torres, November 2011
Strain softening in semi-crystalline polymers, is one of their most important viscoelastic characteristics and these materials are very sensitive to temperature and strain rate. A new phenomenological model with strain, strain rate and temperature dependence on stress was developed based on the Gsell & Jonas model with a new expression used to predict the strain softening henomena, completing the whole mechanical behavior of polymers from initial strain, strain softening and part of the strain hardening. Model verification was performed on four materials and it was
developed to further study the complex deformation patterns in thermoplastic materials subjected to impact loads
Clinton Kietzmann | Lu Chen | Harold Lin Feng | Franco Costa | Ronan Le Goff, November 2011
In recent years, injection molding technologies have been developed which use variable mold heating and cooling to increase part quality without significantly increasing cycle time. These processes are not suited for simulation with a conventional steady-state (cycle-average) mold thermal analysis. This paper presents the development of a new 3D finite element based transient mold cooling simulation capability which includes coupling the mold thermal solution with the mold filling and packing simulation. The predicted transient mold temperatures are validated against measured mold temperatures for two instrumented injection molding trials.
Nanoclays have to intercalate and exfoliate. The extent of intercalation and exfoliation is not understood by the processing industry. Researchers have to develop and nanoclay manufacturers have to supply a product which can intercalate and exfoliate to achieve the desired performance of the final product. The nanoclay powder which is supplied has a BET surface area of 5m2/gm or less. To disperse such a powder from 5 to 750m2/gm is difficult. To salvage such a situation, there has been a relook at minerals which are platey such as talc and mica. The finest talc supplied in the world has a BET surface area of 15m2/gm. It is possible to further grind this talc (also mica) along the basal cleavage to 100m2/gm to 200m2/gm. Such talc, if added to polymers can improve properties.
The substitution of plastic for more traditional
materials stems from its reliability and affordability.
However, with the heightened awareness on
sustainability, plastic from fossil sources are sometimes
perceived to adversely impact the environment. In an
effort to address this issue, a detailed life cycle
assessment of heavy duty sacks made from metallocene
polyethylene (mPE) has been completed. The sacks are
used in packaging powdered products for the
construction industry. The results show that these sacks
have several positive attributes and in many instances,
may be a preferred alternative from a sustainability
perspective. In fact, in manufacturing, transportation
and handling mPE sacks are shown to consume
significantly less energy and emit less greenhouse gas
than paper-based alternatives. Additional environmental
benefits will be discussed.
The objective of this paper is to discuss unique part and
mold design requirements for high volume, cost
competitive compression molding of carbon fiber
reinforced epoxy (CF/E) uni-directional prepregs (UD).
The typical part and mold design for compression
molding of chopped fiberglass reinforced polyester sheet
molding compound (SMC) will be used for comparison.
Information that can be used as a design and processing
guide for composites engineers involved with the
development of high stiffness and strength CF/E for
application in the transportation industry will be shared.
Polymaterials has developed a new high-throughput compounding
(HTC) technology which generates thermoplastic
formulations and DIN-ISO compliant test specimen accepted
by engineers and the plastic industry. This technology
accelerates the development of new compounds and is
also much more cost-effective since only a fraction of
material and time is needed compared to the conventional
process. HTC not only increases the output significantly
but also generates more insights enabling one to push innovation
and to cut time to market for new products. The
presentation introduces the technology and illustrates its
capabilities by demonstrating several case studies.
Michael Thomas Muller | Beate Krause | Bernd Kretzschmar | Ivonne Jahn | Petra Potschke, November 2011
In this study composite materials based on highdensity
polyethylene (HDPE) with fillers containing
nanostructures were prepared using melt mixing. Vapour
Grown Carbon Fibers (VGCF), multiwalled carbon
nanotubes (MWCNT) of the types Baytubes® C150P and
NanocylTM NC7000, anthracite powder, microsilica,
organoclay and expanded graphite (EG) as well as
mixtures of these fillers were used. The amount and
mixing ratios of the hybrid filled systems have been varied
to determine the effect on the achievable level of thermal
conductivity as measured on pressed plates. The filler
dispersion and phase adhesion were studied using
scanning electron microscopy. When limiting the
maximum filler content to 10 wt%, the highest
enhancement in thermal conductivity by 166% was found
for VGCF followed by a 1:1 filler combination of VGCF
with EG (148%).
Long fiber thermoplastic (LFT) composite design
studies often emphasize fiber content but are sketchy on
fiber-orientation, fiber-matrix interface and mold design.
In this paper we detail a comprehensive approach to
designing with LFT materials. Specific examples are
given. Carbon-fiber compounds were successfully
substituted for die-cast magnesium parts by redesigning
the metal part for injection molding. Tailored fiber
architectures were achieved through strategic gate
locations, as advised by Finite Element Analysis (FEA)
and Mold Flow Analysis (MFA). Mechanical properties
were enhanced through modified molding processes.
Walter Michaeli | Christian Hopmann | Silke Allert, November 2011
The use of pulsed cold water instead of tempered
coolant is suggested to be a versatile and cost-efficient
technique for the cooling of injection moulds. However,
the advantages and limitations of such discontinuous
cooling strategies are still a controversial issue. In this
paper the behaviour of a discontinuous temperature
control system is analysed with a particular focus on the
reproducibility of the process and the realisable
dimensional stability of the parts and compared to that of
a continuous cooling. For the investigations both a
conventional and a conformal cooling channel geometry
are considered. It turns out that at high mould
temperatures the warpage of the parts can be reduced by
use of discontinuous cooling, but at the same time the
reproducibility of the process is affected adversely. The
regulation of the discontinuous cooling proved to be
challenging especially in combination with conformal
cooling.
E.h. W. Michaeli, Ch. Hopmann, Klaus Kusters, November 2011
Weld lines are formed during injection molding, when
two flow fronts meet. They are often not avoidable in
complex technical parts. Their presence reduces
mechanical strength, especially in high performance short
fiber reinforced materials. Evaluating the load of highly
stressed parts requires accurate knowledge of the
interrelationship between the type of weld line, its
morphological structure and the resulting mechanical
properties. This paper aims at the development of a
simulation method which enables the mechanical
properties of weld lines to be considered precisely in part
design.
Mariangel Berroterán | María Virginia Candal | Nelson Colls | Magda Castillo | Luis Marín, November 2011
The plastic parts for a float-valve system were designed. In the design was considered the use of PET bottles as floating device instead of the regular spheres, in order to promote the reuse of this plastic container and to decrease plastics residues. Additionally, the part thickness was reduced to use less plastic on the parts, and to decrease cycle times. All molds are two-plate and two cavities. The refrigerating system proposed uses U-shape channel, and the expulsion system is composed by ejector pins. Threaded connector´s mold is more complex due to require two-step opening.
Scott W. Steele | Sumit Mukherjee | Mark Rule, November 2011
The use of performance modeling is becoming
more and more critical to the packaging industry.
This trend is driven both by lightweighting efforts
and the need to shorten package development
times. The primary driver for reducing the amount
of material used in packaging is cost reduction,
with environmental positioning an ancillary
benefit. However, it is critical to not compromise
the shelf life or creep performance of the package,
particularly in regions of the world with
temperature extremes.
This paper will explain key elements necessary
for precise modeling of package shelf-life
performance. The mathematical models
considered are M-RULE® Container Performance
Model and Virtual Prototyping™ Software. Some
examples of how computer modeling has been
applied to optimize package performance will be
discussed.
E.h. W. Michaeli | Ch. Hopmann | A. Rebmann, November 2011
The conventional control of the injection moulding
process is based on machine variables, which cannot
sufficiently characterise the course of the process.
Hence, a system that controls the injection moulding
process based on process variables has been developed
at the Institute of Plastics Processing at RWTH Aachen
University during the last years.
The concept of the self-optimising injection moulding
process is based on this research. This paper describes
the concept of the self-optimising injection moulding
process during the holding pressure phase and the idea
of an extension by an incremental cooling system using
small-sized cooling areas.
Christian Hopmann | E.h. Walter Michaeli | Thomas Baranowski | Barbara Heesel, November 2011
The general aim of the Cluster of Excellence
“Integrative Production Technology for High-Wage
Countries” is to overcome the actual contradictions
between value- and planning-orientation as well as
between scale and scope in production technology. One
important aspect of this approach is the development of
virtual production systems to increase simulation
accuracy and thereby to reduce development times and
costs as well as to optimise the utilisation of material. In
this paper new developments in the field of the
calculation of molecular orientation are described and a
validation with different experimental measurements is
presented.
T. Ottnad, S. Gepp, F. Irlinger, T. C. Luth, November 2011
Miniaturization and individualization are some of
the current and in future ongoing trends in producing
business in general and they also are influencing the
plastics processing industry. To meet the upcoming
challenges a lot of research is being done in the field of
micro-extrusion. This work investigates a method to
identify the phenomenon of extrudate swelling of micro
extruded polypropylene using an optical analyzing
method. Experimental data varying the pressure is
presented and an optical analysis is explained. The results
show the suitability of the method but reveal that some
more experiments have to be done in order to formulate
clear statements.
The role of slip additives as a crucial contributing agent in
product failures due to it’s migration to the surface of
plastic films is explored in the context of 5 case studies
highlighting different aspects of the complex interrelationships
that exist between the base resins, the slip
additive present in the base resins, slip agent added by the
film processor in the form of masterbatches, the color
pigments , processing condition / storage conditions and
the products which are subsequently packed inside the
flexible pouch or flexible laminates.
E. h. Walter Michaeli | Christian Hopmann | Sebastian Grammel, November 2011
This paper presents a 3D numerical model to analyze
the melting process in a single-screw extruder. The
fundamental equations of fluid dynamics are solved using
the Finite Volume Method. The software Fluent
distributed by ANSYS, Inc. was used for the numerical
calculations. The computing domain is a helical-shaped
screw channel. The solid bed is modeled as a fluid with a
very high viscosity by adjusting the formulation of the
Carreau model for temperatures below the melting
temperature. The model predicts the melting length,
pressure build-up and the velocity and temperature
distribution within the channel.
A. B. Coffey | P.R. Walsh | C. Stanley | N.E. Murphy, November 2011
There has been much research in the biomodeling of human blood vessels. Models of human blood vessels can be used for aids in future research of new medical devices that can be preliminarily tested in an in vitro setting and that could potentially lead to breakthroughs in the medical device industry. There is also the possibility to use such models for the training of surgeons, especially for complex operations, analysis of arterial diseases, and to provide the basis for hemodynamic studies. Within the last two decades accurate models have been fabricated using corrosion casts obtained from cadavers and the lost wax process.
Recently, there has been a trend towards replicating the properties of blood vessels more accurately. The use of hydrogels has the potential to achieve this, as it is possible to represent properties such as viscoelasticity, anisotropy, and lubriciousness, all of which have been shown to be present in human blood vessels. The goal of this study is to apply casting methods to a core, which represents similar tortuosity and dimensions to a section of blood vessel, and achieve a low cost model that will represent the dimensional accuracy as well as representing physical properties of blood vessels as accurately as possible. In order to achieve this, poly(vinyl alcohol) (PVOH)/poly (acrylic acid) (PAA) hydrogels were chosen as a material that has the potential to match the properties of blood vessels. The PVOH/PAA hydrogels were prepared using a freeze/thaw processing technique.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
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