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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Process Optimization ? A New Model for Calculation of the Axial Temperature Curve for Twin-Screw Extruders
When conceptualizing and setting parameters for processes on co-rotating twin-screw extruders, the axial temperature development is one of the most important factors. As determing this factor experimentally is, however, extremely time- and cost-intensive, there are many analytical and numerical models with which the temperature gradients can be calculated and/or simulated. These models reduce the experimental effort needed for parameter determination, but they can also deviate strongly from the real process.
The following article will introduce a new model for calculating the axial temperature curve. In addition to the average melt mass temperature, this model can be used to determine the radial temperature development, i.e. the change in temperature in the direction of channel depth. The model is based on an analytical equation, providing significantly faster calculation results than comparable 3D simulations. After introducing the model, the high degree of exactness in the results obtained from it, in general as well as in direct comparison to established models, will be shown by comparison with experimental investigations.
Evaluation of Long-Term Performance of GFRTP for Hot Water Supply
Glass fiber reinforced thermoplastics (GFRTP) are generally used for valves, pumps, and connecters in water heaters. GFRTP, however, are degraded in hot water with the immersion time. In this research, the tensile test and SEM observation were conducted to investigate the degradation mechanism of GFRTP. As a result, it was clarified that reduction of adhesive performance between matrix and glass fiber could be the cause of GFRTP degradation even if the high-performance engineering plastic was used as a matrix. Therefore, it is important to improve the adhesive performance. That is the reason why we are going to make the glass fiber reinforced polypropylene, which has the better adhesive performance between matrix and glass fiber.
Development of Ring Tensile Creep Test Method for Composite Pipes
The composite pipe based with polyolefin resin has recently been developed in order to obtain the higher performance for gas and water distribution. Although the stress rupture test is major test method to evaluate the long-term durability of the composite pipe, it is required to develop the new convenient and easy test method which makes it possible to evaluate the properties of the composite pipe. Therefore, in this study, the tensile creep test with a ring specimen as a new simple test method instead of the stress rupture test was suggested as a method of evaluation of the long-term performance. The results of the tensile creep test with a ring specimen were compared with them of the conventional the stress rupture test. As the results of the new test method indicated the similar tendency as compared with the conventional method, it is suggested that the new test method will have a possibility of replacing the conventional tests.
Application of Taguchi Method on Weldline Strength of Nylon6 Nanocomposites Thin Wall in Mold Decoration Molded Parts
Nylon6 nanocomposites (addition 4.0 wt% Montmorillonite) were used as molding material for thin-wall in mold decoration (IMD) injection molded part (tensile specimen with thickness of 0.6mm). The Taguchi method with L18 orthogonal array was used to determine important factors affecting weld line strength in Nylon6 nanocomposites thin-wall IMD molded parts. It was found that the significant contributing factors in descending order were melt temperature (31.66%), packing pressure (24.76%), mold temperature (13.51%), vent depth (8.43%) and injection speed (6.61%); moreover, higher melt temperature, higher packing pressure, lower mold temperature, lower injection speed and vent depth of 0.1 mm increased weld line strength for Nylon6 nanocomposites thin-wall parts when combined with 0.125 mm thick polycarbonate (PC) film.
The Effect of PBAT on the Physical Properties of PLLA Multilayer Structure Film
Poly(L-lactic acid) (PLLA)/poly(butylene adipate-co-terephthalate) (PBAT) blend films (BF) and five layers co-extruded films (MF) at a variety of compositions were manufactured from the co-extrusion process to evaluate the general physical and equivalent sound level (ESL) properties of both BF and MF. Both films were well produced with the uniform thickness. It was found that the addition of PBAT enhanced the thermal stability, and Tm of PLLA decreased. The mechanical properties such as the tensile strength and modulus revealed the decrease tendency with addition of PBAT due to immiscibility of two polymers, and the elongation at break of PLLA/PBAT BF was significantly increased as compared to that of MF. The energy transfer at interfacial area of multi-layers films under the tensile stress was found to be not efficient as compared to blend samples having matrix-domain internal structure. The addition of PBAT on PLLA had a great effect on the reduction of ESL, and it was suggested that the sound measurement technique used in this study could be utilized as a test tool for assessing the ESL.
Influence of a Substrate Bias on the Adhesion of Silicon Organic PECVD-Films on Polypropylene
Plasma enhanced chemical vapor deposition processes can be used to deposit thin films on plastics. Enhancing gas barrier performance of packages, improving scratch resistance of polymer surfaces or adhesion of subsequently applied coatings or materials are just a few fields of application of these coatings. The properties of the deposited coatings depend on the material to be coated as well as on the deposition process. During the process, a low pressure plasma is excited in front of the polymer material using monomers as a precursor. As a result, a cross-linked thin film forms on the surface. The properties of the interphase and the coating can be varied by changing the process parameters. Regarding the interphase between polymer surface and coating, an interesting parameter is the bias between plasma and substrate. In this study, polypropylene substrates are coated in pulsed microwave-excited low pressure plasmas with hexamethyldisiloxane as monomer. The bias is controlled using a second generator connected to the substrate holder which functions also as an electrode. The adhesion of the coatings is evaluated using pull-off tests in a centrifuge. Furthermore, the growth of the different coatings is analyzed microscopically. The results show that silicon organic coatings applied with a bias of -100 V have a significantly higher adhesion on the PP-substrate compared to coatings applied without an additional bias.
Improvement of Mechanical Behavior of Polypropylene Nanocomposites Varying Nanoclays and Compatibilizers
There is a significant interest in the potential for layered silicates to increase strength, toughness, thermal stability, thermal conductivity, and flame retardancy of polymers. Montmorillonite and hectorite are the most commonly used smectite-type layered silicates for the preparation of polymer nanocomposites (PNCs). The objective of this study is to evaluate the enhancement of mechanical and thermal properties of polypropylene matrices by adding various smectite based nanoclays with various compatibilizers. These PNCs were produced using the Polymer NanoComposite Injection Molding Compounder (PNC-IMC).Tensile strength and Young?s modulus were measured to evaluate the influence of different nanoclays in the PP matrices. In order to study the nanoclay dispersion and the degree of intercalation/exfoliation of the materials obtained, small angle X-ray scattering (SAXS) measurements were carried out.
Carbon Monoxide Reduced Low-Defect Graphene Nanocomposites with Poly(styrene-b-butadiene-b-styrene)
The aim was to prepare poly(styrene-b-butadiene-b-styrene) (SBS) graphene nano-composites with effective dispersion to enhance physical and mechanical properties and investigate the effect of increasing low defect graphene from 1?20 %úw/w. Graphene was produced by rapid thermal expansion using expandable graphite oxide and compared to a commercial graphene. The graphene was further reduced and repaired with carbon monoxide (CO). The matrix phase was SBS. SBS was dissolved in benzene and the graphene was ultrasonically suspended in the benzene solution. A range of analyses: Raman spectroscopy and characterisation techniques: stress-strain tensile mechanical analysis (TMA), thermogravimetry (TGA), and transmission electron microscopy (TEM) were used. CO reduction of graphene removed 84 % of oxide groups and produced the least defects (0.41 D/G ratio). Ultrasonication improved the exfoliation and dispersion of graphene. Dispersion of graphenes in SBS utilised ã-interactions. SBS physical properties improved by the addition of GT-CO: the tangent modulus increased 100 % and strain decreased 94 % as graphene loading increased to 20 %úw/w.
Prediction of Part Dimensions Using Sensed Melt Pressure and Melt Temperature and Estimated Specific Volume
A sensor stack strategy was implemented to acquire melt temperature from infrared detectors replacing ejector pins and melt pressure from a load cell located behind the pin in the ejector plate. Data from the sensor stack was used to predict the part dimensions according to a pressure-volume-temperature (PVT) model. The results indicated that the shrinkage predictions follow the same trends as the observed shrinkage, and could be used to remove issues associated with the delay and accuracy of acquiring equilibrated part dimensions in tight tolerance molding applications.
Flow Analysis of Injection Molding with Inserts or Cores Supported by Retractable Pins
Some injection molds utilize retractable pin supports of inserts. In this process the inserts are initially supported by the pins that are retracted before the melt touches them. This method is commonly used for manufacturing golf balls and similar moldings. Retractable pins can also be used for injection molds with slender cores to minimize the core shift effect.
The article presents algorithms and results of mold filling simulations that take into account movement of the inserts and cores supported by those retractable pins. The simulation is implemented as a new feature of the core shift analysis for mold filling simulation.
Model-Based Temperature Measurement for Thermoforming Applications
Thermoforming generally describes the shaping of three dimensional parts by heating a flat part (sheet) above its softening temperature and subsequently stretching it by means of a mold. The stage of heating is the crucial process step, since the sheet temperature significantly influences process stability and part quality.
In many applications, the sheet is heated in a radiation furnace  and the sheet temperature is controlled simultaneously using infrared sensors. Infrared sensors measure electromagnetic radiation and convert the measured signal into corresponding temperature values. When installed inside of a radiation furnace, the amount of measured electromagnetic radiation that is not attributed to the sheet can be significant, especially in the case when the sheet is heated from both sides and partially transparent for the heater radiation. This, in turn, causes wrong in most cases considerably inflated temperature values given by the sensors.
The aim of this paper is to present a model-based approach, which separates the electromagnetic radiation from the totally measured radiation in order to determine the sheet temperature more precisely. At first, a mathematical description of this approach with made assumptions will be given. Secondly, an experimental setup for the case of unidirectional radiation heating will be presented. This setup is used to verify the mathematical approach. Experimental results will be discussed using a polypropylene as sheet material.
Influence of Material Batch and Moisture Content on the Processing Behavior and Dimensional Stability of Phenolic Molding Compounds
Rising temperature requirements in automotive applications as well as lower target costs require materials with low production costs on the one hand and excellent thermal properties on the other. Due to their specific properties moldable thermoset materials like phenolic molding compounds appear to be an interesting alternative to cast aluminum or expensive high temperature thermoplastics such as PPA, PPS or PEEK. The scope of this paper is to investigate the suitability of such compounds for the large scale production of high-performance parts with special requirements on the dimensional stability.
Synthesis and Crystal Transition of HBA/HNA Copolymer
Thermotropic liquid crystal polymers (TLCPs) with high melting point are of scientific and technological interest because of their typical high strength and modulus, good heat resistance, unique rheological properties and excellent electric properties. With acetylation-melt polycondensation two-step, the HBA/HNA copolymer (PBN) is synthesized from 4-hydroxybenzoic acid (HBA) and 2,6-hydroxynaphthoic acid (HNA). The study of melt polycondensation with the acetylation product 4-acetoxybenzoic acid (ABA) and 6-acetoxy-2-napthoic acid(ANA) show that, with zinc acetate dehydrate as the catalyst, PBN can be prepared with the catalyst dosage of 300 ppm and polycondensation temperature of 320 oC. XRD and POM indicate that the polymer prepared is nematic liquid crystal polymer. By in situ XRD and in situ POM, the connection of microstructure and crystal transition is studied. TGA results that the average decomposition temperature is more than 500 oC with a fine thermal stability.
Correlation between Foam Extrusion Process Parameters, Mechanical Properties and Pharmaceutical Downstream Processing
Over the last decade, pharmaceutical industry and academia have being exploring foam extrusion to enable oral drug products. Foaming provides a new dimension to extrusion operations in the pharmaceutical industry, by facilitating the manufacturing processes and enhancing drug release rates. For this study, foams of hydroxypropyl methylcellulose acetate succinate with different morphology were produced through foam extrusion. Correlations between variables expected to directly influence foam architecture (die size, gas type, gas concentration) and performance properties of the product (mechanical properties, foam densities, and milling behavior) were established.
Ultrasonic Upsetting ? A New Method of Ultrasonic Staking to Join Hybrid Material Combinations
Mixed material joints become more and more important with reference to functional integration as well as weight and cost optimization. Furthermore, the requirements regarding the strength and the surface quality of the joint are also currently increasing. Concerning both criteria, heat staking processes provide the best results. But especially in contrast to ultrasonic staking, heat staking needs long cycle times to create the joint. The present article aims to define a suitable process strategy of ultrasonic staking, named ultrasonic upsetting, combining a high joint-strength with short process times. Additionally, other disadvantages of the conventional ultrasonic staking (e.g. contact of the horn with the mating part, staking of materials with low viscosity) are solved with this process solution.
Optimize the Mechanical Properties of Blow Molded Thermotropic Liquid Crystalline Polymers for Hydrogen Storage Applications
Thermotropic liquid crystalline polymers (TLCPs) are attractive candidates for manufacturing hydrogen fuel storage vessels because of the combination of their outstanding mechanical, barrier, and thermal properties. This paper represents the successful extrusion blow molding of TLCP materials. Significant improvement in the mechanical properties in the machine or hoop direction is observed if a higher amount of strain is applied in that direction. To stretch the parisons biaxially, a new mold with twice the cavity diameter and a parison stretching device have been designed and manufactured.
Effect of Miniaturisation and Process Induced Crystallisation on Mechanical Properties of Microinjection Mouldings
Miniaturized parts weighing few and tens of milligrams represent a large category of microinjection moulded products. Both miniaturization and extreme processing under microinjection moulding make material experience high shear rates and high cooling rates, and have differing morphology and final properties from conventional injection moulding. This paper studied the variation of cavity thickness (from 500æm to 100æm) and process (injection velocity and mould temperature) on morphology and short-term/long-term mechanical properties of miniaturised dumbbell specimens. It was found that oriented skin layer determined molecular orientation and broadly influenced Young?s modulus, elongation and yield stress. It accounted for over 60% of the cross-section when part thickness was below 200æm. Mechanical properties measured from the standard 4mm thick specimen cannot represent the properties manufactured under microinjection mouldings.
Effect of Retort on the Peel Strength of Rigid Plastic Containers
The effect of retorting on the peel strength of Polypropylene (PP) lids sealed to cups was studied. The peel strength increased as the sealing temperature and time increased. However, the peel strength decreased as the samples were retorted or autoclaved at 121øC for 60 minutes. Sealing and the subsequent cooling processes result in an interface that is in a metastable state. During retort the molecules at the interface could rearrange themselves into a more stable state, which could decrease the molecular interaction at the interface. This would decrease the peel strength after retort as seen in this research.
PVC Property Modification Using Styrenics Based Modifier Systems
PVC demand is likely to keep increasing over the next years. It?s competitive price, chemical resistance and processability has resulted in it being used for a wide variety of applications. With the addition of impact and heat distortion modifiers among others, it has become a very popular material for many industries. This paper discusses advancements in the areas of property modification based on styrenics to meet demanding customer requirements across a wide range of PVC applications.
Styrolution as the Nr. 1 styrenics supplier intends to futher contribute to the area of PVC modification through material innovation and technologies.
Computed Tomography X-Ray Imaging - A Novel Technique for Non-Destructive Examination of Plastic Products
The use of traditional X-ray imaging, one in which a 2 dimensional radiograph x-ray image is obtained has had limited use in examination of plastic products. The advance of digital, computing, and processing technology has lead to development of laboratory scale Computed Tomography (CT) X-ray imaging equipment for the use of non-destructive examination plastic products. CT is the process of imaging an object in all directions using X-rays and reconstructing image data to produce a duplicate, three-dimensional digital model of the scanned object. The internal and external structure of the object can then be viewed at any cross-section, point, or angle. CT allows the documentation and memorialization of an object, in its entirety, without destructive analysis and allows movement through the object to view areas of interest.
This feature of CT X-ray imaging makes it a valuable tool for use in plastic product failure analysis. The locations of cracks, voids, and presence of contaminants can be determined very precisely. This paper discusses this technology and its uses in performing plastic product failure analysis.
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