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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A THERMALLY MENDABLE “BRICKS AND MORTAR” THERMOPLASTIC/THERMOSET BLEND
An epoxy/poly(?æ-caprolactone) (PCL) blend with aninteresting 'bricks (epoxy) and mortar (PCL)' morphology was prepared by polymerization induced phase separation (PIPS). The material is capable of thermally mending mechanical damage such as cracks, through an experimentally observed 'bleeding' process. Mechanistically, this is due to the volumetric expansion of PCL above its melting point in excess of epoxy brick expansion, leading to the extrusion of bulk PCL to fill the crack gap and subsequently recrystallize to restore mechanical strength.
METHODOLOGY FOR EVALUATING WARPAGE SENSITIVITY OF PLASTIC MATERIALS
This paper presents research related to the development of a methodology for evaluating the sensitivity of a given plastic material to warpage. The methodology rates a materialƒ??s sensitivity to warpage from each of three different criteria ƒ?? Thermal, Orientation and Process. The study found that two test geometries could be used to determine the three Warp Indices. For the materials tested, on an average orientation induced warpage was more than double process induced warpage. Fiber reinforcements and part thickness had a significant influence on all three of the warp indices.
NEW PROCESS CHAINS FOR REPLICATING MICRO AND NANO STRUCTURED SURFACES WITH BIO-MIMETIC APPLICATIONS
In order to broaden the application domain of microsystems-based products, a number of processing chains that are complementary to those used for batch-manufacturing of micro electro mechanical systems (MEMS) have been recently proposed by the research community. Such alternative process chains combine micro and nano structuring technologies for tool/master making with replication techniques for high throughput such as injection molding (IM). In this research, two new process chains are presented for replicating structured surfaces that are inspired by nature. In particular, a study was conducted to replicate structures incorporating functional features found on the eye of a household fly and on a shark skin. Such features were initially designed by applying a bio-mimetic modeling approach in order to 'embed' in them the targeted functionality. Next, mould inserts, produced by applying two different tool making technologies, were integrated in a tool for micro injection moulding and thus to assess the feasibility of the proposed process chains for replicating micro and nano structured surfaces.
UPDATE ON DEVELOPMENTS FOR SCRATCH AND MAR ADDITIVES; EFFECT OF THE ADDITIVE FORMULATION ON THE SCRATCH PERFORMANCE
Very often plastics manufacturers utilize scratch and mar additives to reduce the occurrence of surface defects. The most commonly used scratch additive in the automotive industry is erucamide (SM2). Recently there have been new additives introduced to the market ƒ?? specifically an olefin grafted silicone (SM3). This paper includes a comparison of the efficacy of SM1, SM2 and SM3 for automotive applications. Although little differentiation is seen at scratch levels of 5 N, the differences become more apparent at loadings of 10 N and higher. Furthermore this paper shows that loading levels of a scratch additive (SM1) can be reduced via addition of a booster additive (N1), thereby lowering the overall cost of the system and enabling implementation for automotive applications.
MEDICAL MOLDING PER THE FDA'S ISO 13485 AND ISO 14971 REQUIREMENTS
The FDA is becoming more stringent in auditing medical device companies (MDCs) for compliance to CFR Part 820 (QSRs), ISO 13485 (Quality Systems) and ISO 14971 (Risk Management) standards. MDCs are responsible for ensuring that both internal and outsourced plastic component suppliers meet these regulations and standards. Correlation Technology (CT) is an effective means for MDCs to flow down these requirements to their molded part suppliers. CT is an effective and efficient technology that enables molders to comply with the Quality standards, to accomplish Risk Management at the component level and to demonstrate their compliance with these requirements to both the FDA and the MDCs.
TAKE THE PRESS SETTINGS OUT OF MOLD-MAKING
Correlation Technology (CT) is a scientific, datadriven method for plastic injection molding that takes the press, press settings and press operator decisions out of tuning a mold to meet part dimensional requirements. Changes to press settings and transferring the mold from one press to another have plagued the mold-maker from the start of mold-making. CT enables the mold-maker to tune the mold in one and only one step while ensuring that mold will make parts with the highest possible dimensional compliance. The results of the mold characterization study are transferable from press-to-press. CT facilitates scaling up from low-cavitation developmental molds to highercavitation production molds. CT enables mold designers and fabricators to deliver molds that will have adequate capability (Cpks) to handle normal customer press variation.
A COUNTER-ROTATING MANDREL DIE FOR THE STUDY OF SUPERIMPOSED SHEAR FLOWS IN POLYMER NANOCOMPOSITES PROCESSING
A counter rotating mandrel die (CRMD) was designed and fabricated in cooperation with Dr. Collin GmbH in Ebersberg, Germany. The counter rotating mandrel die superimposes Poiseuille and Couette flows to achieve a die flow in which shear stresses are bi-helically distributed. The die has been successfully demonstrated for the extrusion of polymer nanocomposites comprising poly(ethylene-ran-methacrylic acid) ionomer (EMAA Na+) / hydrogenated tallow-treated montmorillonite clay blends. Extruded films produced by operating the die in counter-rotation mode exhibited significantly greater in-plane orientation of the clay sheets than extruded films prepared without counter rotation.
DESIGNNOVATION': THE SYSTEMATIC APPLICATION OF INNOVATION WITHIN A DESIGN FOR SIX SIGMA (DFSS) STRUCTURE
Innovation has been perceived historically to be theproduct of eureka moments. It has proven to be a scarceresource for organizations which so desperately have aneed and desire for it but can't seem to capture it. Withcorporations beholden to the innovative process for newidea generation and problem solving, it is no longeracceptable to bet the future of a company on theunpredictable epiphanies of a creative few. This paperoutlines a structured approach to systematic innovationthat is repeatable, predictable, and reliable, thus providinga key to survival in a down-turn economy.
FABRICATION OF MICROPATTERNED POLYMER SCAFFOLDS WITH A CO-CONTINUOUS POROUS STRUCTURE
This article presented a technique for fabricating micropatterned polymer scaffolds having a co-continuous porous structure. Poly (lactic acid) (PLA) was used as a structure-forming material and polystyrene (PS) as a sacrificial one. In this process, a blend of the two polymers was prepared first by melt mixing under appropriate conditions for forming a co-continuous phase structure. Hydroxyapatite (HA) nanoparticles were added to the blend during mixing to reduce interfacial tension and consequently the phase size. Next, the blend was molded into sheets and subsequently hot-embossed for transferring the micropattern on the master to the blend sheet. Finally, the sacrificial PS phase was extracted by solvent to obtain the desired polymer scaffold. This method was successfully demonstrated using the above combination of materials as a model system.
USING DIFFERENTIAL SCANNING CALORIMETRY TO DETERMINE THE QUALITY OF A PVC PART
Failure of unplasticized poly(vinyl chloride) (PVC-U) pipes and fittings may be related to many factors, such as, design, installation, abuse and/or manufacturing. A successful failure investigation may require detailed analysis of all these factors to determine the primary cause of failure. This paper will review current techniques that use aggressive chemicals to qualitatively assess the quality of the PVC pipe or fitting. The paper will also review a technique that utilizes differential scanning calorimetry (DSC). This technique can accurately determine the temperature at which the part was manufactured. It is also able to determine the percent gelation of the PVC material, which is directly related to the mechanical properties of the part.
HYDROGEL MULTISTRUCTURE SWELLING KINETICS BY LIGHT POLARIZED MICROSCOPY
Acrylate based hydrogels synthesized under strict controlled conditions exhibit structures at three different length scales (10-6, 10-4 and 10-2 m) as well as an unusual combination of surface properties, morphology, mechanical properties and swelling capacity. These properties depend strongly on the thermal history during the synthesis and on the cross-linking agent concentration. Mechanical properties, swelling capacity and structures at different length scales of these hydrogels have shown a transition at a critical concentration of cross-linking agent. The swelling kinetics was determined by alternative techniques to the traditional gravimetric method. A novel technique uses a statistic method of analysis of variance (ANOVA) of images taken during the swelling process. Another method calls for the use of light polarized microscopy with a sucrose solution as contrast medium and swelling agent. The time elapsed for determination of the swelling kinetics is a hundred times faster than the traditional gravimetric technique.
LOCAL PRESSURE FLUCTUATION AROUND A CAVITY SURFACE OF A HETEROGENEOUS NUCLEATION SITE
Heterogeneous nucleation in polymeric foaming processes forms at preferential sites such as phase boundaries or additives and requires less energy. Rough surfaces, especially cavities, on a processing wall or on additive particles are commonly found within a polymergas solution, and these are regions where cell nucleation can be initiated. In most previous studies on cell nucleation, a uniform pressure throughout the solution was assumed; and the discontinuity at the interfaces between the additives and surrounding material was neglected. A recent study  has shown that, the pressure and stress fields at discontinuities within a polymer-gas solution vary evidently from the surrounding areas due to the melt flow dynamic induced by the growth of nucleated bubbles; and regions at these discontinuities are the places where cells are propagated. However, the effect of surface geometry of an additive particle or the roughness of a processing wall, which is related to the underlying mechanisms of interfacial enhanced nucleation, has not studied. This paper presents a numerical analysis to investigate the pressure profile around a cavity surface inside a heterogeneous nucleation site. Such an investigation is expected to provide more insights to understand the cell nucleation phenomena.
EXTRACTABLES AND LEACHABLES: WHAT TO DO AND WHY TO DO IT?
The studies used to determine what chemicals (and how much of them) can move in some way from a source material (usually polymeric in nature) to another sink (food, pharmaceutical, the body, the air) falls into the general category of what is termed ƒ??extractablesƒ? and ƒ??leachablesƒ? studies. The reasons the studies are done are to meet regulatory guidelines and to aid risk professionals (toxicologists) in assessing a given products safety. In practice, it is the analytical methods used to detect, identify, and quantify the chemicals that migrate out of the base material that poses the most significant obstacle in helping risk assessors make a determination as to the risk posed by a given product.
A STUDY OF THE FACTORS INFLUENCING THE PERFORMANCE OF A DIRECT TO PLASTICS WATER BASED COATING FOR THERMOPLASTIC OLEFINS
There is an increasing trend towards the use of Thermoplastic Polyolefins (TPO) in the marketplace particularly in the automotive sector due to the desirable mechanical properties. In order to achieve adhesion of coatings to TPO, automotive manufacturers have traditionally used solvent based chemical adhesion promoters or other forms of surface pretreatment to overcome the lack of bonding sites on this low surface energy substrate. Each of these pretreatment methods has their own drawbacks and all add an extra step to the coating process. A water based direct to plastics (DTP) coating for TPO is therefore very desirable due to the lack of flammable, environmentally detrimental solvent as well as the elimination of the pretreatment step. The barriers to achieving adhesion to TPO with a water based coating include the inability to wet out water over such a low surface tension substrate and the lack of bonding sites on the substrate. Once the barriers to adhesion are overcome, the coating must still meet the performance requirements of the finished coating. This paper explores a water based DTP coating and the role that adhesion promoters, surface tension modifiers, and resin systems play in the adhesion and overall performance of the coating on TPO. The study indicates that the selection and concentration of each of these is very important in overcoming the barriers to applying a water based DTP coating to TPO and achieving the overall performance required. In addition, the curing schedule for the coating systems examined plays a critical role in achieving the desired results.
PHASE BEHAVIOR OF BLENDS CONTAINING POLY(RESORCINOL PHTHALATE-BLOCK-CARBONATE) AND POLY(ETHYLENE TEREPHTHALATE)
Polymer blends provide an efficient way of making new materials with improved properties. The miscibility of poly(resorcinol phthalate-block-carbonate)(RPC) and poly(ethylene terephthalate )(PET) blends is examined by differential scanning calorimetry and dynamical mechanical analysis. When the resorcinol phthalate level in RPC copolymers is as low as 20mol%, the blends show limited miscibility. As the resorcinol phthalate level increases from 40 to 80mol%, the blends go from being partially miscible to completely miscible. Understanding this phase behavior change in the context of the classical Flory-Huggin's theory is attempted.
POLYANILINE MODIFIED CLAY IMPACT ON POLYSTYRENE FOAMING ULTILIZING CARBON DIOXIDE BLOWING AGENT
Polyaniline-clay (PANI-MMT) nanocomposites were synthesized through in-situ polymerization of polyaniline with various dopants. Those nanocomposites were used to blend with polystyrene (PS) to form an expandable composite resin, which will significantly impact the foaming process using a CO2 blowing agent. The material composition and foam morphologies were characterized through various analytical techniques, such as, X-Ray diffraction (XRD), SEM, dielectric measurement, UV/vis, and FTIR. Based on our experimental results, we are proposing that the de-doped base form" of Pani-MMT nanocomposites and both "inorganic and organic salt-form" Pani-MMT nanocomposites will act as a "molecular CO2 reservoir" to control the CO2 releasing during the foaming. The selection and optimization on those compounds will be enormously important for developing a new inexpensive and environmental friendly blowing agent for the foam industry to achieve the final goal of replacing the existing CFCs /HCFCs /HFCs blowing agents!"
SIMPLE METHOD FOR CHARACTERIZING PURE MODE I INTERFACE FRACTURE COHESIVE LAW OF OF HYBRID JOINTS BONDED WITH DISSIMILAR ADHERENDS
The interface fracture process of most layered or bonded structures is commonly under the control of mixed mode cracking where the interface shear and normal fracture components exist simultaneously when the hybrid joints are bonded with different adherend materials. In this work, a simple and novel method is proposed to realize and characterize the pure mode I interface fracture for the hybrid joints with dissimilar substrates. The theoretical and experimental results indicate that the present method may be considered as a standard test method for the characterization of hybrid joints with dissimilar materials.
EFFECTS OF CHAIN BRANCHING ON THE FOAMABILITY OF POLYLACTIDE
In this work, polylactide (PLA) foams were prepared via a batch foaming system by using CO2 as a blowing agent. The foamability of four PLA grades were compared and the effect of chain branching on cell morphology was investigated. The thermal properties of PLA were analyzed by thermogravimetry and differential scanning calorimetry (DSC). The extensional viscosity of PLA was measured by using a rheometer with an extensional viscosity fixture (EVF). The relationship between the chain architecture, cold crystallization phenomenon, extensional viscosity and foamability of various linear and branched PLAs are explained in the conclusion.
INSPIRE At-Press TPO Technology
Traditionally automotive Thermoplastic Polyolefins (TPOs) have been made by compounding processes. The mixing of components at the molding press (At-Press) greatly reduces compounding cost while providing flexibility to dial in dimensional and mechanical performance. This technology also offers cost savings via inventory consolidation and simplified logistics. This paper presents results from Dow's INSPIRETM At- Press approach, which is designed to meet high end OEM specifications. The formulations are designed for mixing at the molding machine and delivering excellent talc and elastomer dispersion under the breadth of typical fabrication conditions. Part results validate good dispersion and distribution and equivalent properties to compounded TPOs. Consistency of At-Press process was demonstrated to be at the same level as compounded TPO. In this paper, At-Press blending is shown to be a very viable technology.
CONSTANT-TEMPERATURE EMBOSSING OF SUPERCOOLED POLY(ETHYLENE TEREPHTHALATE) BETWEEN TG AND TM
Constant-temperature embossing experiments were performed on supercooled amorphous PET films. The process was designed to achieve isothermal embossing so that cooling can be eliminated. Rather than using a conventional cooling process for solidification, the supercooled PET films, after rubbery softening, were hardened by crystallization at the same embossing temperature. The resulting cycle time is on the order of the characteristic crystallization time, approximately 1 min or shorter for supercooled PET in a large processing temperature window centered at 180?øC. In the testing experiments, parallel microtrenches of 20 ?¬m width and aspect ratio 2 were faithfully replicated from a silicon master onto the PET film without the cooling stage. The time and temperature dependent thermomechanical behavior of the supercooled PET film was studied to understand the underlying principle of this novel embossing process.
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