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.
A typical laboratory capillary rheometer is piston fed. Which means a piston pushes material down a barrel and extrudes it through a die. It is normally cold fed from the top manually. Here, we have installed a small-scale screw extruder to push material into the barrel, before the measurement begins.
While foam injection molding processes are state-of-the-art in modern industrial plastics processing facilities, the transfer of these technologies to the field of thermoset injection molding has not been investigated. The results presented in this paper outline the potential as well as the challenges of this new technology. While significant weight reductions of up to 20 % have been achieved, surface quality and mechanical properties demand further investigation and optimization of the process.
Extensive study on multilayered coating systems has been carried out to understand the scratch-induced damage mechanisms. The experimental results show that increase in soft base layer thickness improves the scratch resistance. The numerical analysis of the stress and strain field explains the mechanics behind the improvement in scratch resistance in the multilayered coating systems. Usefulness of the present findings for designing scratch resistant multilayered coating systems is discussed.
A comprehensive investigation of the degradation mechanism of polyolefin products and evaluation of their deterioration state using non-destructive methods are essential. The photodegradation of low-density polyethylene was investigated with various methods in a wide range of scales from macroscopic to microscopic. The ability to characterize the initial stage of degradation of these materials using non-destructive Raman spectroscopic measurements is also demonstrated.
While chemically similar, it has long been known that polyethylene (PE) and polypropylene (PP) are immiscible and suffer poor interfacial adhesion when processed as layered films or blends. In this paper we present an examination of the effect that processing conditions, such as extrusion residence time and post-extrusion take-up, have on the interfacial adhesion between PE and PP.
Blends of LLDPE (linear low density polyethylene) and LDPE (low density polyethylene) are used in many film applications. This paper shows how several high performance LDPE resins can be used as a blending component to increase output or throughput on blown film lines as well as to optimize film mechanical properties. In addition, some of these LDPE resins are utilized in shrink films, providing a good combination of shrink and optics, and are also used in foams and extrusion coating among other applications.
Analyses and screw design concepts are presented to control the plastication path of materials in single screw extrusion. The methodology uses analytical solutions for transient heat conduction with shear heating. The design concept uses multiple channels in the transition and feed sections to provide improved control of extrusion scale-up. Two screw fractal designs are presented for comparison with general purpose and barrier screw designs.
Weld lines in multi-gated and windowed products can act as flaws to weaken the mechanical strength of the part. A design of experiments with neat and 40% talc-filled polypropylene indicated that asymmetric melt in-flows during molding could be used to significantly strengthen weld lines in injection molded parts. Product design recommendations are provided.
In micro-injection molding process, the dimension of the characteristic geometry can be similar to morphological feature size inside the polymer. This work investigates the crystalline morphology in the injection-molded polypropylene parts. It has been found that development of crystalline structure affects the filling flow. The molded micro-structure shows the crystalline growth on the surface. The crystalline structure inside micro-groove can be stretched crystal or spherulite.
The shrinkage and warpage behavior of injection molded parts is very complex. By using a new measuring method it was shown for the first time that the warpage can be classified as warping and distortion. In general, warpage can only be reduced substantially by a sufficiently high volumetric compensation in the holding pressure phase. Residual stress measurements show, deviating from the literature, that flow induced residual stresses can also induce compressive stresses in the part core due to pressure holding effects.
Scratch properties of talc-filled polypropylene was quantitatively evaluated by critical loads. Scratch test was conducted following ASTM D7027 standard. Melt index (MI) and talc content were varied to investigate wide range of composition. Tensile test was conducted according to ISO 527 and scratch properties are analyzed in terms of tensile properties.
One of the most important variables for ultrasonic welding is amplitude. While recommended amplitude guidelines are available for many generic materials based on accumulated industry experience, use of specialized and newly developed materials is rapidly increasing. To that end, it is desired to have a method for experimentally determining the minimum amplitude required for a material. This work investigates one possible method to determine minimum required amplitude.
This paper shows how to employ layer splitting in coextrusion to improve tear strength of elastic films. The improvement is done without changing the chemical composition or adding a strength-enhancing polymer. The present work is focused on multilayer elastomeric films made from polymers in one layer that are immiscible in the polymers in the adjacent layer.
Novel open-cell foams were created using the solid-state foaming process in polyetherimide (PEI). The cell size is in the 50 – 150 nm range. The structures’ fluid permeability, gas diffusivity, and tortuosity were determined by applying classical models to experimental data. This new class of materials is expected to have a variety of applications such as nanofilters for dialysis/aerosols, slow release of volatile substances in medical or agricultural fields, and others.
The article discusses commonly used systems for mold venting and their limitations, introducing therefore alternative dynamic venting valves that can help overcome such limitations and improve mold performance.
A recently published 3D failure criterion  for anisotropic materials that incorporates stress interactions is presented. The strength tensor model includes fourth order strength tensor stress interaction components that can be computed based on the slope of the failure surface at distinct stress axes intersections, making the model apt to fit failure surfaces for a variety of anisotropic materials. Experimental data from the literature for unidirectional FRP’s, an anisotropic paperboard material and textile reinforced composites are used to validate the model.
A 3D failure criterion for anisotropic materials that incorporates stress interactions is implemented to predict failure of selective laser sintered parts. Special test specimens were designed, manufactured and tested. Results show that the failure of additive manufactured parts is strongly influenced by the interaction between stresses. The test data shows an excellent fit with a tensor based failure criterion that includes interaction strength tensor components .
The purpose of this paper is to provide an update in the development and commercialization of radiation modified, linear polyolefins including linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP) and ethylene vinyl acetate (EVA) that have been used to produce non-crosslinked, low density foams. This is an important commercial development in that now it is possible to access a broader range of foam properties through material selection to meet challenging performance requirements.
Markets trends of cost reduction, consumer convenience, sustainability & down-gauging drive the need for new and improved packaging solutions. Development of such solutions requires a look across the entire value chain – an Asset to Market look. This talk will focus on what is required for a successful packaging solutions to be launched in a competitive space. Key examples will be presented and will cover the trends related to recyclability and downgaging.
Heat seal lacquer materials are tailored for the types of substrate being sealed together and contents of the package. Both polymer properties and formulation variables can be chosen to target bond strength, activation temperature, and bond failure mode, all being optimized for a given end use. This paper will discuss examples of different polymer properties and formulation variables on the end-use performance in a heat seal lacquer.
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
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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