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

ALUMINUM PIGMENT TROUBLE SHOOTING FOR PLASTICS

Robert Schopp, May 2012

The use of aluminum pigments to give a metallic or glitter effect in polymers has been popular for enhancing the value of plastic parts. Due to their large particle size, aluminum pigments can present some challenges. This paper provides information on the proper aluminum pigment and carrier selection. Recommended methods for blending and compounding will be discussed as proper dispersion can prevent some issues. The use of aluminum pigments in both liquid and solid polymer systems are presented. The focus of this paper is on Trouble Shooting of problems that occur when using aluminum pigments. This paper focuses on issues related to aluminum pigment processing and the finished part appearance. Plastic part fabrication processes can pose challenges, so recommendations are made to trouble shoot these problems and suggest solutions. Problems such as agglomeration, gassing, process orientation, color measurement, plate-out, flow and weld lines are addressed. Some issues such as flow and weld lines can occur with glass flakes and mica pigments as well as aluminum pigments.

THERMAL CONDUCTIVITY OF POLYCARBONATE-CARBON NANOTUBE COMPOSITES

Nayandeep K. Mahanta, Jill Kunzelman, May 2012

Polycarbonate composites were prepared with as-received and surface functionalized carbon nanotubes (CNT). The anisotropic thermal conductivity was measured using two separate steady-state techniques for the in-plane and through-plane conductivity. The non-covalent surface treatment of the CNT was seen to improve the thermal conductivity of the composites. In addition, the consistency in the thermal conductivity enhancement due to surface treatment illustrates that the functionalization did not adversely affect the intrinsic thermal conductivity of the CNT.

STUDY ON STRUCTURE FORMATION OF PVA NANOFIBERS SPUN BY FREE SURFACE ELECTROSPINNING

Hiroyuki Itoh, Kok Ho Kent Chan, Masaya Kotaki, May 2012

It is important to modify internal structure of nanofibers in order to increase the mechanical properties. We aim to control the internal structure by changing spinning conditions in free surface electrospinning. In this study, effects of electrical conductivity of polymer solution and spinning distance on internal structure of PVA nanofibers were investigated. In order to change electrical conductivity, ionic salts were added into the solution for electrospinning. By increasing electrical conductivity and decreasing spinning distance, i.e. increasing electrostatic force to draw the polymer jet in electrospinning process, d-spacing of the (1 0 1) plane was found to decrease, i.e. packing of polymer chains was enhanced.

COMPARISON OF COMMON ELECTRICAL TESTING METHODS FOR THE MEASUREMENT OF INJECTION MOLDED PC/CNT COMPOSITES

Jane M. Spikowski, Jill Kunzelman, May 2012

The measured electrical properties of polycarbonate (PC) and carbon nanotube (CNT) composites depend not only on the quality of dispersion achieved during compounding, but also the conditions used to injection mold and test the resistivity of a specimen. This study compares the information provided by various two-probe and four-probe test methods in the context of a simple injection molding optimization study. The test methods represent a variety of commonly cited test procedures based on published standards relevant to the conductive composites industry. Varying the injection speed and barrel temperature profile significantly impacted the measured bulk and localized electrical resistivity as measured using all test methods. Discrepancies between the test methods also varied with molding conditions, reflecting the complex features of injection molded CNT composites. Finally, this study addresses the resulting implications for evaluating the electrical performance of CNT composites.

MULTI-DISCIPLINE PROBLEM SOLVING IN A MULTI-FACETED GLOBAL TECHNICAL STRUCTURE

James Rediske, May 2012

Today's global economic environment frequently demands that our companies have more than one center for technical competence. However those same economic demands seldom allow for creating two or multiple separate and equal facilities. This therefore necessitates the development of different sites with basic overlap, but perhaps individual specialized capabilities and personnel. These sites and Specialists can then communicate and take a coordinated team approach to solving customer, application, or manufacturing challenges when needed. In this discussion we will attempt to elaborate on a particular instance that serves as a good example of team work in an environment such as described.

ULTRAPRECISION MOLD MANUFACTURE FOR MICRO INJECTION MOLDED MICRO OPTICS

Ekkard Brinksmeier, Oltmann Riemer, Lars Schönemann, May 2012

Diamond Micro Chiseling (DMC) has recently been developed as an ultraprecision machining process for the manufacture of structured optical molds. This process allows the generation of prismatic microstructures at a size between 50 ?m and 500 ?m, which cannot be manufactured by conventional processes like turning, milling or planning. Prismatic geometries are achieved by using specifically designed V-shaped diamond tools, a special tool kinematics and an ultraprecise 5-axis machine tool. Representative examples of these structures are corner-cube retroreflectors in the abovementioned size. In this paper main developments for the successful application of the DMC process will be demonstrated and examples for micro injection molded plastic micro optics will be given. Machine requirements, process and control developments as well as characterization of machined mold structures and replicated parts will be shown.

ANALYSIS OF WOOD PARTICLE DRYING FOR ROTOMOLDING APPLICATION

Nicolas Ward-Perron, Denis Rodrigue, May 2012

This study focused on estimating the moisture content inside wood particles when dry-blended with polyethylene powder to produce wood/polymer composites (WPC) for application in a rotomolding process. The effects of different parameters on the dynamics of drying were evaluated: initial moisture content of the wood particles, total thickness of the powder bed, temperature ramp and wood concentration in the mixture. As expected, higher initial humidity took longer to obtain equilibrium moisture and higher material thickness led to slower drying dynamics (time to equilibrium). On the other hand, increasing the temperature ramp decreased drying time. From the results obtained, it is clear that drying the wood particles before blending with the polymer is not necessary for rotomolding applications as most of the humidity will have left before the polymer starts melting and sticks to the mold walls.

COMPARISON OF WATER-QUENCH VERSUS AIR-QUENCH BLOWN FILM PROCESSES – PART II: THERMOFORMABILITY

Karen Xiao, I-Hwa Lee, Robert Armstrong, May 2012

This paper investigates the film property differences between water-quench versus the traditional air-quench blown film samples. In Part I, it was found that the overall crystallinity of the water- quench film was much lower than that of the air-quench film. This resulted in higher WVTR and OTR values. The effect of process parameters such as water ring position, water temperature and annealing temperatures on the final film properties were found to be insignificant. In the second part of this study, thermoformability of the samples will be investigated in detail. Thermoforming trials were performed on both a batch former and an automated Multivac thermoformer.

PURE PERFORMANCE: THIN WALLED FLUOROPOLYMER CONTAINERS

Cathy Edgington, Michael Altimore, Kurt F. Hayden, May 2012

High temperature fluoropolymers are a likely material of choice for critical components in demanding applications. Fabrication methods for producing three-dimensional, thin walled, hollow objects using these materials include assembling films and molded fitments utilizing welding operations. An alternate technique has been developed which eliminates the need for these assembly steps. This method rapidly produces containers suitable for environments between -165°F and 350°F while exhibiting superior mechanical, optical, gas barrier and chemical resistance properties.

EFFECT OF CLAY CONCENTRATION ON THE RHEOLOGICAL PROPERTIES OF TRIBLOCK COPOLYMERS NANOCOMPOSITES

Leice G. Amurin, Danilo J. Carastan, , Nicole R. Demarquette, May 2012

Block copolymers are materials with many applications in the field of thermoplastic elastomers. Their properties can be further improved by the addition of nanoclays. However, the morphological and rheological properties of these hybrid materials are not very well known. In this work, the effects of clay concentration on the evolution of morphology of two block copolymers, (SEBS and SEBS-MA), presenting an aligned cylindrical morphology, when submitted to elongational flows was studied. The elongational test was performed using a Sentmanat elongational rheometer and the morphology of the clay-containing block copolymers was studied using small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM).

CONTINUING STUDIES OF DUCTILE-BRITTLE TRANSITION OF THE SECOND KIND

Zhenwen Zhou, Haiying Zhang, Alexander Chudnovsky, Kalyan Sehanobish, Mridula Kapur, Dane Chang, May 2012

A transition from a continuous to discontinuous crack propagation and associated changes in crack growth equations has been reported in our previous work. Such transition was named Ductile-Brittle transition of the second kind (DBT2). Recent advances in continuing studies of DBT2 are reported in this paper. The highlights of an experimental program designed to understand the root causes of DBT2 are briefly described. It is found that the temperature, at which DBT2 takes place, shortly “transition temperature 2” (TT2) depends on stress field characterized by stress intensity factor (SIF). TT2 dependency on SIF is expressed in form of DBT2 diagram. It suggests that DBT2 may take place in a process of crack growth at a given temperature. This suggestion is confirmed by direct observations in the present program as well as by the fractographic analysis of HDPE pipe brittle fracture in temperature accelerated long-term sustained pressure test. The DBT2 diagram is a valuable tool for design of an accelerated testing for lifetime of PE structures in durable applications.

NATURAL FIBER REINFORCED THERMOPLASTICS (NFRTP) PROCESSED BY ROTOMOLDING

Nicolas Ward-Perron, Denis Rodrigue, May 2012

In this work, wood fibers/linear medium-density polyethylene (LMDPE) composites were produced by rotational molding. The effect of wood particle sizes (0-1700 microns) along with wood contents (0-20 wt.%) were examined. In particular, the simple dry-blending technique was used to introduce the wood particles inside the polymer matrix before feeding the mixture to the rotational mold. From the samples produced, a complete characterization was performed in terms of density, morphology, as well as tensile, flexural and impact properties. The results indicate that increasing wood content increases both the Young’s modulus and the flexural modulus, while decreasing ultimate strength, strain at break and impact strength. Depending on the wood particle size, an optimum wood concentration was obtained for the range of parameters studied, especially when a mixture of different wood sizes is used.

OVERCOMING TECHNOLOGICAL ISSUES ASSOCIATED WITH COLOR ADDITIVES IN POLYMERS VIA SOLID-STATE SHEAR PULVERIZATION

Philip J. Brunner, John M. Torkelson, May 2012

A continuous, industrially scalable process known as solid-state shear pulverization was used to disperse colorant materials in polypropylene, which was followed by melt-processing. This novel two-step technique was shown to overcome several issues often encountered with conventional melt-processing, which include the elimination of “swirl patterns” and color shifting. We also show through this two-step procedure that we can achieve a similar color to a part made only by melt-processing by using approximately 25% less colorant.

BARRIER PROPERTIES OF GRAPHENE-BASED POLYMER NANOCOMPOSITES

Matthew Thompson, Sushant Agarwal, Prithu Mukhopadhyay, Rakesh Gupta, May 2012

Exfoliated graphite sheets, or graphene, are currently being studied for their electrical, mechanical, and thermal properties. This material also has great potential for mass transfer barrier properties when dispersed in polymer to form polymer nanocomposites (PNCs), and these graphene-based PNCs (GPNCs) should yield better properties as compared to PNCs made using other nanofillers, including nano-layered silicates. In this work, commercially-available graphene was surface treated with silanes to impart hydrophobic character to the graphene surface allowing for better dispersion in a matrix of polyvinyl acetate (PVAc). This was verified using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moisture diffusion through PVAc samples containing up to 1.5 wt.% treated and untreated graphene with platelets of two different aspect ratios was studied at room temperature which showed that the initial moisture diffusivity decreased with increasing filler content. The diffusion coefficient was found to reduce by as much as two orders of magnitude from that of the neat polymer. These results are superior to those obtained by us in the past using organoclay as the filler, where the observed reduction was about 20%. Clearly, graphene platelets form an excellent barrier against water diffusion.

SUREFLO®: A NEW AND HIGHLY EFFECTIVE PROCESS ADDITIVE FOR THERMOPLASTICS

Xiaofan Luo, Brian P. Sarvas, John D. Jungjohann, Aaron Puhala, May 2012

In this paper, we explore the effects of a new process additive, SureFlo®, on the rheological and crystallization behavior of semi-crystalline polyolefins. It was found that SureFlo® can dramatically lower melt viscosities and delay crystallization, resulting in improved processability of the polymer. As we show in a finite-element simulation of a typical injection molding process, the use of 7 wt- % SureFlo® results in significant decrease in fill time and increases productivity by ~20%.

DETERRA® BIOBASED POLYMERS-NEXT GENERATION MATERIALS FOR DURABLE APPLICATIONS

Adam R. Pawloski, Brandon J. Cernohous, Ashley Pinault, Jeffrey J. Cernohous, May 2012

In the past decade, the market for biobased polymers has grown dramatically. Much of this growth has been in the packaging market, where biobased polymer films (i.e., PLA and PHA) have displaced conventional LDPE and LLDPE. Packaging is a natural application for biobased polymers given the short life cycle and consumable nature of this product. Recently, consumers have begun to demand green alternatives in applications where durable plastics have historically been utilized. For example, PVC has been under intense scrutiny in recent years. PVC’s inherent chemical nature and the additives it is often formulated with have been identified by several organizations targeting chemicals that can harm the environment. In certain markets, like the building and construction market, there is a salient need for a biobased material that can be used as a PVC alternative. Leadership in Energy and Environmental Design (LEED) certification and other local codes and regulations are creating a new market for durable biobased polymers. One may consider durable biobased polymers a misnomer. However, the inherent nature of biopolymers like PLA, is such that they can function in one environment (e.g., interior building applications), but degrade in another environment (i.e., compost). This work describes several grades of polymeric compounds that been recently developed by Interfacial Solutions for durable applications. These products are currently marketed under out deTerra® Biobased Polymer trade name.

SUPRAMOLECULAR IONIC BLOCK COPOLYMERS

Nicole Brostowitz, Longhe Zhang, Kevin A. Cavicchi, Robert A. Weiss, May 2012

Supramolecular polymers employ non-covalent interactions to bind functional polymeric units together into effective macromolecular structures. Non-covalent interactions can lead to unique self-assembly behavior useful for processing and smart materials. This paper considers the use of ionic interactions to produce supramolecular polymers. The balance between association and dissociation of the ionic species can produce interesting properties of physically bonded multi- block copolymers. Controlled polymerization techniques were adapted to synthesize well-defined end- functionalized polymers with low molecular weights.

OPTIMIZATION AND SENSETIVITY ANALYSIS OF A FILM DIE

Hossam Metwally, Patrick C. Lee, May 2012

This study shows how response surface based goal driven optimization can be used to optimize the shape of a film die (coat hanger die). A parametric model for the die geometry is constructed containing three (input) geometrical parameters. Output parameters are defined as the pressure drop and the flow uniformity. A Design Of Experiments (DOE) approach is implemented to cover the feasible design space. A mathematical response surface is then constructed to represent the correlation between the output parameters and the input geometrical parameters. Using screening of the response surface, two optimum designs are obtained that will reduce the pressure drop and increase the flow uniformity. Furthermore, assuming possible variations in the material's shear thinning index and flow rate, to account for different material grades and throughput, the sensitivity of the pressure drop and the flow uniformity in the two suggested optimum designs are compared. It is desired to select the one design among these two suggested optimums that will have the smallest variations in flow uniformity when the power law index is changed.

REINFORCING THERMOSETS USING CRYSTALLINE DESOXYANISOIN STRUCTURES

Polina A. Razina, Alan J. Lesser, Beom-Young Ryu, Todd Emrick, May 2012

This paper presents the preliminary investigation of desoxyanisoin molecule as an in-situ self-reinforcement agent that can also improve thermoset flammability properties. Both isothermal curing and radial temperature gradient curing conditions for epoxy network crosslinking and desoxyanisoin phase separation were investigated. Desoxyanisoin did not increase the thermoset flammability. However, this crystallizable small molecule is promising in terms of creating long microchannels and distinct reinforcement domains. Straight fiber-like crystals on the mm scale were observed during the isothermal cure, whereas the thermal gradient cure resulted in complex and rich crystallization morphologies.

GEOMETRY OF TRIPLE SCREW EXTRUDERS TO PROMOTE MIXING

Yingsheng Xing, Nan Jiang, Changwei Zhu, Baorui Yan, Travis Getzie, Jianguo Zhou, May 2012

The development of screw extruders has experienced several milestones over the past century, giving rise to the wide and extensive application of screw extruder in polymer, food, and other industries. The newly developed triple screw extruder began to catch close attention owing to its versatility in its changeable screw axes adjustments, multiple intermeshing regions, multi-displacement of melt flow, lower ratio of length and diameter, and higher output and energy consumption ratios. In this article the geometry of three screws inside the triple screw extruder was studies, and the result shows great advantage of performance in mixing for the triple screw extruder while comparing with twin and single screw extruders.