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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TECHNIQUES FOR TROUBLE SHOOTING AND ANALYSIS OF BLOW FILM RELATIVE TO PROPERTY DEVELOPEMT
The physical property development of blown film products are dependent on at least four parameters: first, the properties of the base resin, second, the strain and strain rate in the machine and transverse directions, third, the temperature profile of the process from die to the “freeze line,” and fourth the crystallization rate as a function of position above the die. The last three issues will be discussed in this paper since they are related to troubleshooting and scale up.
THE EFFECT OF WELL EXFOLIATED AND DISPERSED GRAPHENE OXIDE SHEETS ON THE POLYSTYRENE SUPERCRITICAL CARBON DIOXIDE FOAMING
We investigated the nucleation effect of well exfoliated and dispersed GO sheets on polystyrene scCO2 foaming. To get PS/GO nanocomposites with well exfoliated GO sheets, a method based on latex concept were employed. The characterizations based on XRD and TEM demonstrated the exfoliation and well dispersion of GO sheets in polymer matrix. The scCO2 foaming were carried out and the results showed the well exfoliated GO sheets could be a high efficient nucleation agent.
COMPARISON OF WATER-QUENCH VERSUS AIR-QUENCH BLOWN FILM PROCESSES – PART I: FLAT FILM PROPERTIES
This paper investigates the differences in film properties between water-quench versus the traditional air-quench blown film process. The effect of process parameters such as water ring position, water temperature and annealing temperatures on the final film properties were studied. Barrier properties such as water-vapour transmission rate (WVTR) and oxygen transmission rate (OTR) were also compared. Results were correlated to the crystallinity differences observed between the samples using optical microscopy and WAXD.
MELT MIXED PCL - MWCNT NANOCOMPOSITES PREPARED AT DIFFERENT MIXING SPEEDS
Composites of poly(caprolactone) (PCL) and multiwalled carbon nanotubes (MWCNTs) were produced by melt-mixing in a small scale compounder by varying the screw speed between 25 and 400 rpm at a constant mixing time of two minutes. By that, different levels of dispersions, as assessed by quantitative analysis of area ratio of remaining primary agglomerates from light microscopy, were achieved. With increasing screw speed the state of dispersion increases and levels off starting at about 100 rpm.
THERMAL CONDUCTIVITY OF POLYCARBONATE-CARBON NANOTUBE COMPOSITES
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.
TIPS FOR OPTIMIZING TWIN-SCREW EXTRUDER PERFORMANCE
A collection of 17 techniques is presented for increasing the performance of twin-screw extruders. Processors may be aware of some of these tips, but many are not well known. All are based on solid scientific principles, and have been proven in dozens of extruder installations. Also, all techniques presented are easy to apply, so the benefits can be realized quickly.
ACCELERATED TESTING AND LIFETIME PREDICTION FOR PLASTIC PIPES
Short-term tests are used in many branches of Science and Engineering to predict future outcomes of long-term processes. It is important to ascertain criteria of similarity between the short-term test and real life events. The criteria for predicting lifetime must reproduce the mechanisms of field failures and have a technically sound procedure for extrapolation of a relatively short test data. A quantitative modeling approach as an alternative to “empirical” extrapolation is proposed in this paper.
STUDIES OF DEGRADATION EFFECTS DURING ROTATIONAL MOLDING
This paper describes a program to assess degradation effects on polyethylene, the most common polymer used in rotomoulding. Polyethylene was compounded with a variety of antioxidant (AO) combinations, pulverized to a powder and then rotationally moulded. The impact strength of samples cut from the rotomoulded parts was correlated with assessments of material condition made using Carbonyl Index (CI) and Yellowness Index (YI). Significant differences were observed between different AO formulations.
TROUBLESHOOTING PLASTICS INDUSTRY POWDER STORAGE & HANDLING PROBLEMS USING FLOW PROPERTIES
This paper describes four basic flow properties of powders and bulk solids and how these properties may be used in diagnosing flow problems in existing handling processes. Included are cohesive strength, frictional properties, permeability, and segregation tendencies. Examples of common flow problems in typical handling systems are provided as well as how a specific flow property may be the controlling factor. Using these properties, a system may be evaluated, and corrective actions developed to eliminate the flow-related problems.
VARIABLE STRENGTH STRESS BEAD ANALYSIS IN A TWIN SCREW EXTRUDER
An experiment has been created that relates stress distribution history with residence time distribution. To quantify the results, stress beads that break up at a specific stress were used to measure the percent of material that sees those critical stress values throughout the extruder. Two different strength stress beads were used along with two different mixing section geometries. This paper describes results for a range of different throughputs and speeds in the extruder.
SUREFLO®: A NEW AND HIGHLY EFFECTIVE PROCESS ADDITIVE FOR THERMOPLASTICS
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%.
ADDITIVE MIGRATION IN POLYMER FILMS
Additives are commonly blended into polymer films. Oftentimes the additives and the film resins are incompatible, which leads to blooming of the additives to the film surfaces. This research focuses on quantifying the amount of additive exuded to the surfaces over time. Examples include slip agents, anti-fogging agents, and drugs in polyolefin and biopolymer films.
INFLUENCE OF PROCESS PARAMETERS OF AN UNDERWATER PELLETIZING SYSTEM ON THE MOISTURE OF WPC (WOOD-PLASTIC-COMPOSITE) PELLETS
An underwater pelletizing system was used for the production of WPC pellets. In order to avoid the costs of drying prior to injection molding, the pellets must have a low moisture content before bagging. Selected screening results of the effects of different parameters on the moisture of WPC pellets are shown in the paper. By adjusting the appropriate process parameters, producers can save energy and costs by doing without or limiting the following drying steps.
EVALUATION OF FRACTURE CHARACTERISTICS OF POLYETHYLENE BLOWN FILMS USING THE ESSENTIAL WORK OF FRACTURE (EWF) WITH VARIABLE FILM ORIENTATIONS
In this paper, essential work of fracture (EWF) tests for five polyethylene blown films are conducted. The fracture toughness of those samples was evaluated based on test results. The effect of the film orientation on the fracture toughness of materials was evaluated. The work calculated from load-displacement curves obtained from double edge-notched tension (DENT) specimens was analyzed as the ligament increases
EXAMINATION OF THE PERFORMANCE OF A HIGH SPEED SINGLE SCREW EXTRUDER FOR SEVERAL DIFFERENT EXTRUSION APPLICATIONS
This study investigates the extrusion characteristics of a High Speed Single Screw Extruder, (HSSSE), to determine suitability for use in several different extrusion applications including Sheet, Fiber and Extrusion Coating. The study demonstrated that a properly designed HSSSE can greatly improve the processing capability of a small diameter single screw extruder for a wide range of applications.
ENCAPSULATED GRAPHENE WITH POLYSTYRENE BY ULTRASONICALLY INITIATED IN-SITU EMULSION POLYMERIZATION
Graphene was successfully encapsulated with polystyrene via ultrasonically initiated in-situ emulsion polymerization in this paper. The XPS, FTIR, TEM and SEM results confirmed the PS encapsulation of grapheme nanocomposite (PS-G) was achieved through ultrasonically initiating technology without any initiators. The graphenes exhibit good compatibility and dispersion in the PS matrix. The thermal stability of nanocomposites is improved with the incorporation of graphene.
POLYMER EXTRUSION CONTROL SYSTEM DESIGN
In this paper, the overall extruder control system is constructed by two control loops, a multi-input-multi- output (MIMO) control of the barrel temperatures and a single-input-single-output (SISO) control of the melt pressure at die output. Advanced control algorithms are adopted to control these key variables. Experimental results demonstrate the fast response, near-zero overshoot and precise tracking performance of the proposed control strategies. And ultimately the effectiveness of the whole controller is well reflected by product quality.
STUDY OF PRODUCING MICROCELLULAR INJECTION MOLDED PARTS WITH IMPROVED SURFACE QUALITY
This paper describes a novel approach to achieve swirl-free foamed plastic parts using the microcellular injection molding process. With a better understanding of the cell nucleating behavior, which is governed by the degree of supersaturation, one can delay the onset of cell nucleation during mold filling, thereby allowing a solid skin layer to form on the part surface prior to foaming. The theoretical background of this approach as well as the experimental results are presented.
THE INFLUENCE OF FLOW ENHANCED CRYSTALLIZATION ON SHRINKAGE PREDICTION
Comparison is made between a flow-induced crystallization model and measurements made on injection molded samples of a PBT material. The magnitude of shrinkage in the flow direction and the direction perpendicular to flow are found to be in good agreement, as is the degree of shrinkage anisotropy. The flow-induced components of the model are demonstrated to be crucial for the correct prediction of the shrinkage anisotropy.
RECYCLE TECHNOLOGY OF USED PLASTIC MATERIALS
This paper describes the recycle technology of used plastic materials such as waste HDPE films and containers, waste caps for PET bottles, and used PET bottles with caps and films. The fusion joining strength of extruded sheets of waste HDPE films and containers using a compatibilizer was firstly studied. A compounding technology of used PET bottles with caps and films using a compatibilizer was secondly studied.
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