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
Bio-Based Polymers from Soy Chemistry
Research on the use of soybeans to produce polyurethane polyols
unsaturated polyester resins and thermoplastic fibers has been funded
by the United Soybean Board (USB). The USB funds a wide range of
activities including research and development of new industrial products
made from soy. These developments have resulted in new patented
technology. Commercialization of this technology has resulted in the
production of unsaturated-polyester resins for fiberglass-reinforced
composites and urethane polyols for polyurethane foams. The commercial
applications of these bio-based polymers are found in a wide range
of applications in the transportation markets.
Epoxy Thermosets Modified with Novel Nano-Scaled Self-Assembled Block Copolymers: Toughening Mechanisms and Extension to Composites
A unique approach to toughening thermosets has been identified by
introducing small amounts of amphiphilic block copolymer. The result
is a good viscosity-Tg-toughness balance. In this work the fracture
behavior of these modified epoxies was carefully studied in an attempt
to understand the toughening mechanisms that exist. The findings
suggest that cavitation in even these nano-sized spherical micelles is the
primary mechanism of toughening. These findings were also found to
be a strong function of the cross-link density of the host network with
higher levels of plastic deformation at the crack tip being observed in
the low-cross-link density systems. Glass-fiber-reinforced composites
made with epoxies modified with these toughening agents were found
to have improved fatigue resistance.
Zero-Emission Acrylic Thermoset Technology
In today’s environment there is an ever-increasing desire to ‘circle the
square’ reaching high-performance durability light weight and manufacturing
flexibility without increasing and even trying to lower overall
system costs. This presentation will discuss a new enabling technology
platform engineered towards these ends: cross-linked thermoset acrylics.
These are non-flammable zero-emission systems that contain no volatile
or hazardous components at any stage of their life cycle. They are easy
to use in molding processes and ideally suited for today’s ‘greener’ lightweight
automotive composites. Their application in natural fiber
composites will also be outlined in the presentation.
Long-Fiber Reinforced Thermoplastic LFT-D & Thermosetting D-SMC Processes for Lightweight Parts Production - Trends & Recent Applications
The direct process of producing long-fiber-reinforced thermoplastics
(LFT-D) is highly innovative and economical for producing semi-structural
and structural components as well as cosmetic parts with grained
surfaces. The advanced plastic-hybrid developments with tailored LFT
and E-LFT technologies fulfill crashworthiness requirements. Similiarly
the direct processing of fiber-reinforced thermosetting materials – direct
strand molding compound (D-SMC) – is focused on the reproducible
manufacturing of the compound resulting in a constant part production
at a high level minimizing material costs and expensive post-mold operations
and paint processes as well as reducing logistical costs. The high
flexibility in composing the recipe in selecting the resins fillers and reinforcements
result in the high degree of freedom of this process.
Development of an Adhesive-Primer for Polypropylene Composites
Joining is often one of the critical steps in the fabrication of composite
products. However the low polarity and inert characteristics of
polypropylene composite surfaces cause many problems in the assembly
of these composites with dissimilar materials. In order to overcome the
adhesion issues an epoxy-based primer was developed and the compatibility
of several commercial adhesives with the primer was evaluated.
Results showed very-good lap-shear strength of up to 15 MPa with
substrate failure. The performance of the primer was also evaluated
between -30 and 80°C and after conditioning in humidity. While lapshear
strength decreased with increasing temperature it remained
unchanged after conditioning. Finally different practical approaches to
apply the primer film to a polypropylene continuous-fiber composite
were investigated including techniques to apply the primer during and
after composite consolidation.
Electrically-Heated Moulds of CRP Composite Materials for Automotive Application
The moulding system FIBRETEMP describes a procedure to heat
moulding surfaces efficiently with a consistent distribution of temperature.
The heart of this invention the use of carbon fibres to conduct
electricity as well as integrating the heating element and the structure
within the surface to be heated. These moulds are highly energyefficient
and extraordinarily dimensionally stable while also being
produced at low cost. This technology has already been proven in
manufacturing composite parts and has nearly halved cycle time for
some applications due to its efficient heating characteristics.
Fatigue & Vibration Response of Long Fiber Reinforced Thermoplastics
While numerous advances have been made in the manufacturing
methods of long-fiber thermoplastics (LFTs) their dynamic response in
terms of fatigue and vibration damping has been a subject of limited
study. There is presently no standardized design information for a
composites / automotive designer for use of LFTs in situations of longterm
fatigue and vibration. The behavior of E-glass fiber / polypropylene
LFT composites has been characterized for their fatigue behavior and
vibration response in the present study. The work provides an understanding
of the influence of extrusion / compression-molded long fibers
and the fiber orientation that is generated during their processing.
Results will be useful to designers in accounting for fatigue life and
damping factors.
Automotive Thermoplastic Composites...Industry Structure & New Technologies Respond to a Global Recession
The deterioration of macroeconomic conditions has severely impacted
automotive production and the autoplastics supply chain. Thermoplastic
composites – especially long-glass-fiber versions – will benefit from
these conditions via the development and implementation of new resin
and compound technology as well as advances in fabrication technology
adapted to the requirements of a new automotive paradigm and new
applications. Our outlook is for gains in high-performance long-glass
(and other fiber) reinforced-PP compounds in competition with shortglass
and mineral-filled compounds.
Structural Thermoplastic Composites: Filling the Gap between Stamped Steel & Molded Composites
For over 50 years the auto industry has been gradually replacing steel
with plastics and molded composites. Substantial progress has been
made particularly in applications where significant parts consolidation
is possible using composites. The need is greater than ever for further
substitution of composites for steel but large performance gaps
between steel and composites limit the rate of progress. Current
gap factors include: stiffness and strength molding thickness process
cycle time ability to weld to steel and cost. This presentation will
address approaches for eliminating each of these gap elements for
non-appearance parts using a systems approach based on new
thermoplastic composite technologies.
Latest in Additive Developments for Long Fibre Reinforced Polymers
Composite parts made from long-fibre-reinforced thermoplastic (LFT)
material systems are known for their high impact and tensile strength.
And due to the benefits of the outstanding price to performance relationship
of the in-line compounded (ILC) direct-LFT (LFT-D) technology
used for production of composites based on the use of polypropylene
and glass fibres it has achieved consistently more applications in the
automotive industry. But LFT-based automotive applications are mainly
used for parts with large surfaces which can contribute significantly to
the total amount of VOCs and odor inside a car. The current work
explains a feasible approach of using commercial additives – provided as
a complete system – in combination with VOC- and odor-reducing
additives to further enhance the mechanical and outgasing properties of
the PP / GF composites produced by LFT-D / ILC technology.
Digimat Material eXpert - From the Material Lab to the Efficient & Optimal Design of Reinforced Plastic Parts
Fast and cost-efficient design of higher quality lighter and more energy
efficient vehicles is one of the key success factors for today’s automotive
industry. Predictive CAE and the use of composites materials offering
good weight to mechanical-performance ratio are two ingredients that
will help the industry moving forward profitably. We will introduce the
DIGIMAT nonlinear micromechanical-modeling technology which can be
used to predict the nonlinear behavior and failure of multi-phase materials
based on their underlying microstructure (e.g. fiber content fiber orientation
fiber length etc.). The multi-scale material-modeling process used to
model the reinforced plastic part will then be presented.
Damage Modeling of Injection-Molded Short- & Long-Fiber Thermoplastics
An integrated approach linking process to structural modeling has been
developed to predict the nonlinear stress-strain responses and damage
accumulations in injection-molded long-fiber thermoplastics (LFTs).
The approach uses Autodesk® Moldflow® Plastics Insight’s fiber orientation
results predicted by a new fiber-orientation model developed for
LFTs and maps these results to an ABAQUS® finite-element mesh for
damage analyses using a new damage model for LFTs. The damage
model which has been implemented in ABAQUS via user-subroutines
combines micromechanical modeling with a continuum damagemechanics
description to predict the nonlinear behavior of LFTs due to
plasticity coupled with damage. Experimental characterization and
mechanical testing were performed to provide input data to support
and validate both process modeling and damage analyses.
Sensing When the Molding Cycle is Over.... The Key to Productivity & Product Consistency
Dielectric cure monitoring has been used in thermoset laboratories for
decades to characterize materials. Historically attempts to take the
technology to the production floor where the benefits can be
maximized in production tools have failed due to shortcomings in
sensor durability and system reliability. Breakthroughs in dielectric
sensor design have resulted in the development of durable in-mold
sensors that can operate on the production floor. Thermoset molders
can now “see” changes in flow and cure inside their production tools
allowing automatic “real-time” adjustments for process variation and
enabling significant gains in productivity and quality. Benefits to compression
and injection molders include: 10-25% reductions in cycle time
improvements in quality and reduction of scrap and a better understanding
of flow and cure rates inside the mold.
Engineering Aspects of Designing with Pultruded Carbon-Fiber Composites
Often times a composite component can be used to replace a metallic
component providing a significant reduction in weight while providing
little or no loss in strength or stiffness. For automotive engineers to
further utilize composites in new applications it is important to
understand the mechanical behavior of the material in all the critical
loading directions. This paper focuses on the relevant tests necessary
to characterize the mechanical properties of a pultruded carbon fiber
composite material. The mechanical properties evaluated include
tension compression interlaminar shear and fatigue testing in the fiber
direction. Included is a discussion on key aspects of the testing in order
to ensure reliable results. Also a set of design criteria is developed for
the use of the material according to the measured properties.
Progress in Simulations for Short & Long Glass Fiber Thermoplastic Composites
The development and implementation of lightweight materials using
fiber composites made by injection molding represents an engineering
challenge due to the inability to control the fiber orientation in the
required direction of mechanical demand. This paper presents progress
in developing the capability of predicting fiber orientation in simple
and complex flow geometries for highly concentrated short-glass-fiber
suspensions and the extension of this approach to long-glass-fiber
suspensions. Three important aspects included in the approach are
the implementation of new theories to model fiber orientation the
evaluation of model parameters from rheological experiments and
the use of stable numerical methods based on discontinuous Galerkin
finite-element method.
Initial Finite Element Analysis of Bond-Line Read-Through in Composite Automotive Body Panels Subject to Elevated Temperature Cure
The Automotive Composites Consortium (ACC) is conducting a multiyear
project to develop a better understanding of the root causes of
the visual surface deformation effect known as bond-line read-through
(BLRT). BLRT is associated with bonded automotive Class A exterior
panels and produces out-of-plane deformations on the order of 0.010-
0.050 mm. The ACC is studying the relationship between material and
process factors and BLRT severity. The majority of the investigations
have focused on SMC composite panels bonded with urethane and
epoxy adhesives under elevated-temperature cure conditions and
subsequently primed and topcoat painted. An investigation was
conducted to see if analytical tools could predict the BLRT effect
observed in the physical experiments. The present work describes
the initial effort to model the BLRT effect using a finite-element
analysis (FEA)-based approach. As part of this effort detailed threedimensional
FEA solid models were developed for two idealized panel
configurations: (a) an outer panel with an adhesive bead and drops and
(b) a bonded outer/inner panel assembly. Results were predicted for
the case of an idealized elevated-temperature adhesive cure condition
using a steady-state thermo-elastic analysis. The predicted surface
curvature results indicated a good qualitative agreement to available
measurement data with the analysis over-predicting the BLRT severity.
Progressive Ply Failure Analysis for Composite Structures
Design engineers working with composite materials typically use a linear
finite-element-analysis (FEA) solution and a failure-index calculation
based on the current state of stress in the model. However this type
of analysis can only provide accurate results up to first-ply failure
because of the linear assumption. This presentation will show how
nonlinear progressive-ply failure analysis can go beyond first-ply failure
and simulate subsequent damage propagation through a structure.
This allows engineers to make a better assessment of conditions for
ultimate failure so they can optimize their designs and also provide
guidance on the most appropriate physical-test program.
Analysis of Woven Glass Fiber Reinforced Thermoplastic Composites under Varying Strain Rates
Increased use of polymer matrix composites depend on having a
deeper understanding of their mechanical response under varying
strain rates. In this study the mechanical behavior of thermoplastic
woven composites was investigated under varying strain rates between
5.0 x 10-5 s-1 and 5.0 x 102 s-1 using a screw-driven universal testing
machine and an impact testing and imaging apparatus. Results yielded
stress vs. strain curves over the full range of loading rates highlighting
the strain-rate sensitivity exhibited by the thermoplastic composites.
In addition the non-contact strain-measurement system revealed the
effect of woven architecture on the mechanical behavior of thermoplastic
woven composites.
CHARACTERIZATION OF VIRGIN-RPET COMPOSITES
Thermoformed polyethylene terephthalate (PET) produce trays (clamshells) produced by a large retail supplier using virgin resin were compared to PET clamshells containing 30, 70, or 100% recycled-PET (RPET). Comparisons were made of functional groups, ultravioletvisible (UV-Vis) light absorption, and thermal properties. An increase in the crystallization temperature was observed as RPET increased when compared to virgin PET. This suggests that the crystallization temperature (Tc) may be used as a quantitative indicator for determining the amount of RPET in a plastic composite.
SYNTHESIS AND PHYSICAL CHARACTERIZATION OF BIODEGRADABLE
PLA/PHBV FOAMS
This paper examines the effect that blending two
biodegradable polymers has on the thermal properties and
morphology of the resultant foams blown with carbon
dioxide (CO2). Polylactic acid (PLA)
Polyhydroxybutyrate-co-valerate (PHBV) and blends of
both were foamed and characterized in terms of thermal
characteristics relative density cell size and foam
morphology. The results indicate that although PLA and
PHBV are immiscible the presence of small quantities of
PHBV could lead to low density foams with finer more
uniform cells.
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