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.
This study quantifies how different sized particles distribute themselves in bi-axially rotationally molded parts. The paper will demonstrate that within normal particle size distributions found in rotational molding, that it is difficult to obtain well-sorted layers in the final molded part. This paper compliments recent papers on powder characteristic in rotational molding.
Underfills can improve flip chip reliability. However, the fillers used in some underfills to enhance coefficient of thermal expansion (CTE) properties can be dispersed unevenly, causing less than optimal reliability. In this study, underfill dispensing was conducted using various fill patterns. Experimental results show that particle migration is a secondary mechanism, which causes uneven filler distribution. Particle settling mainly occurred during the curing process, rather than during dispensing, and was affected by the surface tension.
In this paper, numerical methods to analyze the wire sweep during semiconductor-chip encapsulation are presented. The flow simulation necessary for wire-sweep analysis is based on a three-dimensional model. Different methods to calculate the force on the wire from the flow simulation results have been investigated. The calculation methods have been applied to typical semiconductor-chip encapsulation cases. The comparison between numerical and experimental results in terms of wire-sweep values shows reasonable agreement.
Conductive fillers are frequently added to thermoplastics such as polyesters to impart electrical conductivity; however, the addition of these fillers can be detrimental to the impact properties of the plastic. Reactive impact modifiers such as ethylene-methyl acrylate-glycidyl methacrylate copolymers (E/MA/GMA) are effective for toughening polyesters, but they can also interact with carbon black making it ineffective for imparting conductivity. Copolyester formulations exhibiting conductivity and good impact strength are realized by varying the GMA level.
Thermal wave imaging (TWI) technique using an infrared thermal camera has been used to follow the mechanical deformation of polypropylene nanocomposites. Images were acquired real-time during fracture toughness testing. TWI proved to be a useful tool to identify the differences in deformation mechanisms as well as to distinguish the plastic contribution in each of the specimens. Calculations of surface energy were done using data obtained from the thermal images.
The influence of organically modified montmorillonite (Mt) on the stress-strain behavior and structural development of polypropylene-grafted-maleic anhydride film was investigated. The presence of nanoparticles causes a decrease in overall birefringence when these films are stretched from partially molten state. On the other hand WAXS analysis indicate ,the orientation in the crystalline regions of PP was found to increase for films stretched to same true strain when nanoparticles are present.
Isothermal crystallization kinetics of Polyamide-6, Polyamide-66 and their nanocomposites (NC) were studied using differential scanning calorimetry and high-pressure dilatometry. Calorimetry data for all samples follow Avrami’s equation. High pressure dilatometry yields two regions for PA-6 and PA-6NC crystallization: initially for the formation of ?- and ?-forms, and later for only the ?-form. Only one region was observed for PA-66 and PA-66NC under high pressure. Relevant kinetic parameters are discussed.
The demand for thermoformable Polypropylene food container is rising. Polypropylene homopolymer does not offer high cold impact properties. The polypropylene copolymers offer better cold impact properties at the reduced crystallinity and hence the rigidity and top use temperature. In this article, an attempt was made to coextrude polypropylene with SIS core to achieve better cold impact strength. Cake-baking trays were thermoformed from these sheets. The wall thickness distributions of the trays were used to compare the thermoformability of these sheets.
In the MID, which is an injection molded substrate electronic circuitry is formed three-dimensionally on, it is important to achieve high adhesion strength between metal film and a substrate.To study the adhesion by mechanical properties in the skin region of a substrate, a new evaluation method called “micro-cutting test” was proposed. We calculated the energy release rate and showed that it has positive correlation with the peel strength considering fracture phenomena.
In the recent decade PET-Bottles became more and more widespread. In order to extend the shelf life of sensitive beverages an improvement of the barrier behavior of the PET is essential. One new option to achieve this aim is the novel plasma polymerization process. With this process the cycle time may be reduced compared to other already established processes and no FDA approval is necessary, since only the exterior of the bottle is coated.
Cast unoriented Polylactic acid(PLA) films were biaxially stretched in both sequential and simultaneous modes to a series of stretch ratios and were then subsequently annealed to induce higher crystallinity and dimensional stability. Wide angle X-ray scattering analysis of these as stretched and annealed films were carried out to assess the effect of stretching mode on development of crystal structure and orientation during stretching and annealing processes.
Today, the usage of plastics extend to fields, where they have to stand high compressive load. It is often a problem to dimension these parts in a technically safe and economically meaningful way. One reason for this is the lack of suitable values. Due to this, a stress-appropriate dimensioning is not possible and in most cases values from tensile tests are used. Therefore, the aim of the current investigations at the IKV is to establish a guideline for the determination of characteristic compression values for plastics.
The addition of glycerol monostearate (GMS) to low density polyethylene (LDPE) and polypropylene (PP) foams will not only affect the blowing agent permeation but also affect the antistatic performance. A comparison study is made between LDPE and PP foam by measuring permeation rate of a blowing agent, surface static potential, surface resistance, and static decay of the foams. A differential effect of GMS in antistatic properties and gas permeation properties in both PE and PP foam has been found and is related to the rate of crystallization.
In this study we assessed the fracture toughness, KIc, and the impact resistance of syntactic foam reinforced with glass microspheres of different densities and polymer binder as a function of microstructures. The preliminary results showed that both KIc and the linear elastic energy release rate, GIc, increased with increasing volume fraction of glass microspheres and the increase was higher for microspheres possessing a higher density. The latter also demonstrated a higher impact resistance.
Styrene-acrylic acid copolymers were successfully expanded into low-density foam using sodium bicarbonate as the blowing agent. Sodium bicarbonate reacts with the acrylic acid moiety to form sodium acrylate, thereby releasing carbon dioxide and water that act as the blowing agents. The ionic cross-linking resulting from association of sodium acrylate aids in bubble stability. Closed-cell foams having densities below 40 kg/m3 were readily achieved on a conventional extruder with no special cooling zone. Foam sheet was prepared by the technology without using an organic blowing agent.
High density closed-cell HDPE foams (450-950 kg/m3) were prepared by compression molding using 0-3 wt.% azodicarbonamide as a chemical blowing agent. The samples were then used to measure their flexural, shear, and tensile moduli. The data obtained were compared with models to determine which one represents best the overall property of these polymer foams. We found that thin skins (0-5%) have an important effect of the flexural and shear moduli of polymer foams, while they seem to have negligible effect on tensile properties.
This paper presents the effects of the die geometry on the expansion ratio of extruded polystyrene (PS) foams blown with CO2. Three groups of interchangeable filamentary dies were used to thoroughly represent the die parameters. The experimental results reveal that a strong relationship exists between the expansion ratio of extruded PS foams and the die geometry through its effects on the pressure-drop rate, die pressure, premature cell-growth time and initial shape of extrudate.
A new polyetherimide homopolymer with a Tg of ~250°C has been produced. The resin has the melt processability of lower Tg polyetherimides but increases heat related properties by ~30°C. The performance features of this resin will be discussed along with some of its polymer blends. The new polyetherimide sulfone is miscible with existing polyetherimides allowing a range of transparent materials to be produced.
Glass filled polyetherimide blends can offer a wider range of attractive performance features: non-halogen flame retardancy, high strength and stiffness and excellent dimensional stability. One drawback to these resins has been their relatively low flow in injection molding applications. New additive technology has been developed that can improve flow ~25-35% while retaining other important performance features. Commercial products using fiber glass and milled glass blends have been developed using this new technology.
We have developed two novel methods for measuring isotropic stress development in thermosetting resins during cure and subsequent thermal cycling. We use a sealed stainless steel spherical pressure vessel and thick-wall tube to impose three-dimensional isotropic constraints. The strain at the outer surface of the load cell is monitored by strain gauges. The isotropy of the stresses in tension and compression are examined for both methods.
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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