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
FAILURE ANALYSIS : MIGRATION OF PIGMENTS & SLIP ADDITIVE
CASE STUDIES FROM THE INDIAN SUB-CONTINENT
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.
POLYETHYLENE: PROCESS SENSITIVITY IN
ROTATIONAL MOLDING
Rotational molding is a unique process that puts
unusual demands on the average polyethylene. This paper
looks at the optimum process conditions for different
polyethylenes and the sensitivity of impact properties to the
oven time and temperature. Process conditions become
critical for maintaining impact properties while running
multiple types of molds on one spider or varying from
standard process conditions with like molds.
Renewable Based High Performance TPU
The company Merquinsa SL | located in
Barcelona | Spain | produces classical
polyurethane as well as new (ECO)
polyurethane based on several raw materials
from renewable sources. This particular study
was based on biogenic oil as primary renewable
source for TPU.
A new family of thermoplastic
polyurethanes (TPU) is presented. This new
TPU series has application for polyurethane
adhesives | polyurethane for extrusion | and
injection molding markets. A full range of
vegetable plant-based sources derived from
bifunctional polyols has been developed. The
reaction of these polyols in the TPU
formulation allows new TPU with a renewable
content ranging from 30% to 90% by weight.
Compared to the standard petrochemical-based
grades | the new ‘green-TPU’ shows better
hydrolytic resistance | and maintain equivalent
mechanical properties like first-class
thermoplastic polyurethanes. Merquinsa will
present the latest results for its ECO-TPU
range | based on different renewable raw
materials.
RADIATION CROSSLINKING: HIGH PERFORMANCES MATERIALS FOR PLASTIC MOULDED PARTS
Radiation crosslinking has been in use since the
seventies for halogen-free and heat-resistant cables and
wires | for hot-water pipes or for heat shrinkable tubes,
and tyres. During the last decade | the technology has
been developed rapidly on plastic moulded parts | not
only by the means of Electron Beam (largely used for
extruded products) | but also under Gamma rays. It
improves considerably the performances of a great
number of plastics among those thermoplastics,
elastomers and TPE. It reinforces their dimensional
stability in chemically aggressive and high temperature
conditions. Such modified polymers offer new material
potentialities and solutions for various sectors:
packaging | automotive | E&E.
A MULTICRITERIA SIMULATION OPTIMIZATION METHOD APPLIED TO INJECTION MOLDING
Injection Molding (IM) is one of the most important processes for mass-producing plastic products. To help im-prove and facilitate the molding of plastic parts | advanced computer simulation tools have been developed. This paper presents a simulation optimization methodology for IM processes which consider multiple performance measures. It is able to find a set of efficient solutions without having to evaluate a large number of simulations. Its main compo-nents are metamodeling | design of experiments | and Data Envelopment Analysis. The method is illustrated and de-tailed here using a real injection molding case.
ADVANCES IN PLASTICS JOINING TECHNOLOGIES FOR THE ASSEMBLY OF MEDICAL DEVICES
With demand for the use of plastics in Medical Devices expected to continue growing | there is also a growing demand for improved control and analysis of related assembly processes. Additionally there is a growing demand to use plastics in MEMS and Micro-fluidics for analytical and drug delivery devices. Therefore manufacturers are increasingly looking for joining technologies that are particulate free and will not occlude miniature channels. These trends have led to the introduction of several new methods to control | monitor and analyze the assembly process as well as led to the use of new plastics joining technologies such as Laser and Infra Red Welding.
STRUCTURE AND PROPERTY CHANGES INDUCED BY WEATHERING TO VARIOUS PLASTIC PACKAGING FILMS
The effect of accelerated weathering on the structure
and properties of single | metallized and multilayer films
used in food packaging was studied | by exposing
specimens of the above films to repeated ageing cycles,
under the combined action of UV radiation | humidity
and heat. Films made of polypropylene (PP) undergo
severe chain scission upon irradiation and lose
mechanical strength. The metallic coating cannot
prevent PP from degradation. PE and PET films show
modest decrease of mechanical properties. Multilayer
films (PE/EVOH/PE | PE//PET) present a decrease of
mechanical properties reflecting degradation of their
weak component.
Electrically conductive PC/ABS polymer nanocomposites for automotive industry
Multiwall carbon nanotubes are widely studied as nanostuctured electrically conductive filler for polymers with high efficiency at low percentages. In this contribution the physical and thermal properties of PC/ABS based nanocomposites obtained by melt compounding and containing different amounts of nanotubes and nanoclay were investigated. A complex selective segregation of fillers inside specific polymer phases has been observed | thus explaining the low percolation threshold obtained for electric conductivity. The goal was to obtain lightweight electrically conductive polymers in order to reduce the chemical treatments necessary for the chrome-plating of the automotive components | with enormous economical and ecological advantages.
Lab scale development and industrial scale-up of PET based nanocomposites technology
for packaging applications
Polyethylene-terephthalate (PET) has become the
dominant material for packaging due to its optical clarity
when blow moulded and relative low permeability to
oxygen and carbon dioxide. In order to further improve
PET’s barrier properties | if impermeable nanoparticles are
incorporated into the polymer | the gas molecules are
forced to wiggle around them in a random walk | hence
diffusing by a tortuous path. Moreover | the molecular
mobility in the polymer matrix is diminished | thus leading
to a decrease in diffusivity of such small molecules.
In this research two different strategies have been
followed: the first | based on blending PET with an
aromatic polyamide (PA) and the second based one on the
use of different kinds of inorganic nanoparticles. Several
nanocomposites based on pristine PET or PET/PA blends
and different nanoclays (natural and organically modified
layered silicates | POSS® | i.e. polyhedral oligomeric
silsesquioxanes) have been prepared by melt blending
optimizing formulations and process parameters.
Moreover industrial trials proved that the nanocomposite
materials developed could be successfully stretch-blow
moulded to give bottles with decreased gas permeability
than PET.In particular PET/POSS based bottles are
characterised by an optical clarity comparable to the one
of pristine PET based containers.
MULTIFUNCTIONAL ACTIVE NANOCOMPOSITES FOR FOOD PACKAGING APPLICATIONS
Results on the active performance of oxygen scavenging,
free radical scavenging and antimicrobial clay-based
nanocomposites are presented. The antioxidant nanoclay
was modified to exhibit high dispersion and efficiency
when incorporated into EVOH and in a multilayer system
of LLDPE-EVOH-LLDPE. Oxygen scavengers based on
iron were also incorporated into LDPE | HDPE and PET,
which exhibited some color but little impact in optical
properties. Finally | incorporation of silver based clays
into PLA matrixes allowed to obtain antimicrobial
composites | showing high antimicrobial activity.
The presented active systems are alternatives to preserve
and extend the shelf-life of packaged products.
ELECTROSPUN NANOFIBROUS MATS BASED ON POLY (LACTIC ACID) AND POLY (ε-CAPROLACTONE) CONTAINING TETRACYCLINE HYDROCHLORIDE AS AN ACTIVE WOUND DRESSING
Electrospun nanofibrous mats made from poly
(lactic acid) and poly (ε-caprolactone)
containing tetracycline hydrochloride antibiotic
as an active wound dressings were prepared and
their properties investigated. Samples of poly
(lactic acid) and poly (ε-caprolactone) solutions
in chloroform/dimethylformamide (9/1) with 9,
12 and 15 (w/v)% containing 500 μg/ml drug
were prepared. These nanofibrous samples were
then investigated by pre-designed tests such as
scanning electron microscopy | water-uptake
capacity | UV-vis spectroscopy and antibacterial
drug evaluations. The results showed that 15
(w/v)% poly (ε-caprolactone) samples with 500
μg/ml concentration tetracycline hydrochloride
had a higher release rate efficiency compared
with the other nanofibrous samples.
POLYSILOXANE/LAYERED SILICATE HYBRIDS: MODELLING OF MECHANICAL PERFORMANCE IN RELATION WITH NANOCOMPOSITE STRUCTURE
Nanocomposite blends | based on condensation type
polysiloxane rubber | reinforced with organically
modified montmorillonite (OMMT) nanoparticles | were
prepared via the sonication process. Two grades of
commercial montmorillonite | namely Cloisite 30B and
Cloisite 20A | with different types of organic
modification were studied. A significant improvement
of mechanical properties of the pure polysiloxane was
observed by the incorporation of the examined types of
clay reinforcements. Comparison between the
experimental and theoretical values of elastic modulus
was performed by the use of micromechanical
simulation models | such as the Halpin-Tsai model | that
interrelates Young’s modulus with clay structure in the
nanocomposite.
TRENDS AND ADVANCES IN MULTILAYER STRUCTURES
Over the years that polymers have been in practical use there has always been an application where the properties of different layers within the final product have been used to produce superior properties over that for any single layer polymer. Despite the advances in polymers this principle has continued to grow in all areas of use. The paper will review the progress in the areas of packaging | construction | automotive and biopolymers from both the polymer properties and manufacturing methods. The role of nanoparticles will be reviewed along with other methods of reducing permeation through polymers. Production methods reviewed will be mainly those associated with extrusion processes including injection moulding | cast extrusion | sheet extrusion | profile extrusion and blown film extrusion.
Investigation of the Chemical Resistance and the Material Aging Conditions of Polyethylene for Pipe Applications
The chemical resistance of polyethylene (PE) for pipe applications was investigated with special regard to physical and chemical material aging. Therefore, tensile tests were conducted on films which were exposed to two different aggressive media for different predefined periods of time and at two different temperatures as well as on films which were not exposed to the media. The impact of the media on the Young´s modulus E, the stress at yield σy, the strain at yield εy and the strain at failure εf were studied. Potentially physical or chemical material aging was investigated by the degree of crystallization, the Oxidation Induction Time (OIT) and via Infrared (IR)-spectroscopy.
IMPRESS | an innovative pilot injection-compression moulding platform for the production of micro-nanostructures on plastic parts
IMPRESS targets the development of a technological injection moulding platform for serial production of plastic components incorporating micro or nano scale functional features. The platform is based on most advanced facilities divided in three modules:
- tool manufacturing | involving different technologies of micro- nano direct manufacturing | from top-down to bottom-up such as self-assembling,
- injection moulding | including equipments fitted with innovative hardware technologies to improve replication quality and capability,
- intelligence | dedicated to advanced process control and online metrology integration.
Beside this large panel of facilities | three case studies will be presented for biology | medical and energy applications.
We present the main results obtained during the first year of the project.
Multi-objective Optimization Strategy For The Design Of Injection Mold Cooling System
The manufacturing of thermoplastics parts needs a cooling phase to give the shape to the part. In injection molding | cooling can represent more than 70 % of the total cycle time. This is the reason why cooling channels have to be designed with great care in order to meet quality with efficiency requirements. In this paper | we propose a methodology to optimize the geometry parameters and coolant temperatures of the channels based on the use of modeFRONTIER® software combined with the injection molding simulation software MOLDFLOW®. Multi-objective optimisation will be carried out with criterions based on quality and cycle time minimization.
THE RIGHT CHOICE - NATURAL AND ACCELERATED WEATHERING TEST METHODS COMPARED
Weathering and light exposure are important causes of damage to coatings | plastics | inks | and other organic materials. This damage includes gloss loss | fading | yellowing | cracking | peeling | embrittlement | loss of tensile strength | and delamination. For many manufacturers | it is crucial to formulate products that can withstand weathering and light exposure. Accelerated weathering and light stability testers are widely used for research and development | quality control | and material certification. However | the importance of outdoor testing cannot be overlooked.
Accelerated testers provide fast and reproducible results. The most frequently used accelerated weathering testers are the fluorescent UV accelerated weathering tester (ISO 4802-3 | ASTM G154) and the xenon arc test chamber (ISO 4892-2 | ASTM G155). In recent years | low cost and easy-to-use testers have been developed.
This paper compares two accelerated weathering test methods: fluorescent ultraviolet and xenon arc. The paper will describe the strengths and limitations for both techniques due to: simulation of the forces of weathering | including sunlight | temperature and moisture | mounting of test specimens | control of test parameters | and operational considerations.
MICROSCOPIC EXAMINATION OF A HOT WORKING TOOL USED FOR PLASTIC INJECTION
The failure of a mould-part used for hot-forming is investigated. The die | made from AISI H13 steel was intended for the production of plastic cups. The mould-part exhibited a | single uniform crack through thickness | after five millions working-cycles | whereas it’s predicted working life was ten millions cycles.
Data were collected regarding the material selection | manufacture and operational history. The die was optically inspected. Hardness measurements were carried out and chemical analysis was performed. Detailed optical and scanning electron microscopy observations suggest the type of failure and the factors that led to it.
PRELIMINARY FAILURE EXAMINATION OF A TOOL USED IN TYRE WASTE
RECYCLING - CASE STUDY
Tyres consist of synthetic rubber | metals and linen.
Tyre waste decomposes after hundreds of years | and its
presence is detrimental for the environment. Standing
water | trapped into tires may be a permanent pollution
source | while tyre waste next to a forest increases the
possibility of fire. European legislation imposes the
recycling of tyre waste | which includes the following
three steps: shredding in strips | cutting strips in small
pieces | and powder production from the pieces. At the
last stage magnets remove the metallic pieces | while
centrifugal screens remove the linen. Metals are sold to
the steel industry as scrap | linen is used in limekiln as a
combustion material and the rubber flakes are used in
numerous applications (e.g. road surface construction,
concrete additives | mouse pads | etc.).
CORRELATION BETWEEN DIFFERENT MICRO-STRUCTURAL PARAMETERS
WITH PHYSICAL/MECHANICAL PROPERTIES OF POLYETHYLENE BLOWN
FILMS
A wide range of PE materials | including LLDPE,
HDPEs and LDPE were used for preparation of the blown
films. By changing processing conditions | different
structures for these blown films were produced and their
structural parameters investigated. Establishing
fundamental /structural model between structural
parameters and tensile modulus of blown films was the
objective of this work. A model for the tensile modulus
was proposed and correlated to some structural
parameters including crystallinity | orientation factors for
crystalline c-axis and amorphous phase | lamellar
thickness and crystal size. The measured modulus and
calculated one were compared and a reasonable
agreement was found between them.
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