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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Material Handling and Blending Systems for Molding and Extrusion
Molding and extrusion lines rely on the auxiliary equipment that works with them. This equipment supplies the regrind, resin and additives, cools the process, maintains critical temperatures and even monitors the entire operation. Inadequate process cooling, material handling or size reduction equipment can cause many problems, including the following:; Inadequate process cooling can reduce product output; Poor temperature control can cause product quality issues; Material can be contaminated if not handled and stored properly; The output of the line can be reduced, and even interrupted, if the material is not conveyed to the extruder at the required rate; Product quality will suffer if the material is not blended and metered into the extruder throat at the correct ratios; Excess dust caused by poor size reduction equipment can create processing problems. The following auxiliary equipment is crucial to any molding or extrusion process, and needs to be taken into consideration:; Cooling tower system; Chilled water system; Temperature control units; Bulk storage of the raw material; Material conveying system; Blending and feeding equipment; Crystallizing and drying systems; Size reduction systems. This paper will focus on material handling and blending systems – the other areas will be discussed at a later time.
STRAIN HARDENING: AN ELEGANT AND FAST METHOD TO PREDICT THE SLOW CRACK GROWTH BEHAVIOR OF HDPE PIPE MATERIALS
Resistance to slow crack growth is an important material property of polyethylene which determines the application lifetime, especially for utility pipe applications. Usually, the slow crack growth resistance of materials is accessed by time consuming testing methods such as NPT, FNCT, PENT, etc. These methods require often the use of notched samples, the use of specific fluids (e.g. detergents) and elevated temperatures. Here we present the outline and validation of an elegant method to predict slow crack growth resistance in materials in a simple, accurate and fast way. The resistance to slow crack growth is predicted from a simple tensile measurement at 80 C. It will be shown that the slope of the stress-strain curve above the natural draw ratio (i.e. the strain hardening regime) correlates very well with the results obtained by the full notch creep test (FNCT), Notch Pipe Test (NPT) and the stress intensity ranking of the cyclic loaded Cracked Round Bar test (CRB) of the same materials. This strain hardening method is elegant in that it does not require notched specimen and/or detergents. Besides the advantage that the method is easy to implement in laboratories, its main advantage is the dramatic decrease of measurement times from thousands of hours to only a few. This method is very suitable in the development of new grades, but also very valuable as a batch release test for both resin suppliers and pipe converters.
TOUCHNESS OF MICROCELLULLAR POLYCARBONATE FOAMS AND IT’S DEPENCE OF THE TEMPERATURE
This investigation analyses the notched impact strength of microcellular polycarbonate which was produced by injection molding using physical blowing agents. By varying different processing parameters, such as blowing agent concentration or the injection velocity, injection moulded plates were produced and characterized with regard to morphology and the Charpy notched impact strength. A temperature-dependent analysis concerning the correlation between the foam morphology and the notched impact strength was carried out. Additionally investigations were performed to find out if the failure mechanisms, which occur at low temperatures, also function the same when exposed to temperatures higher than 80°C.
MOLDING PROCESS AND SCREW MELT PEAK POINTS T-P SENSOR
From end of screw return melt residence through injection to ejection of a molded part to screw return end time is the thermal dynamic molding process cycle. A micro-bead melt sensor indicates the imposed strains of temperature and radial force strain as melt density “K” electro-motive force (emf) readout. A nozzle melt density sensor profiled consecutive molding cycles of melt fill to final peak pack. The melt pack interruption by screw return time to final mold cure will be presented.
EFFECT OF HIGH TEMPERATURE OXIDATION ON MECHANICAL PROPERTIES OF 2D CF/SIC COMPOSITES
In the field of thermal shielding for aerospace applications Cf/SiC composites are raising great interest, provided that they are protected from oxidation by suitable coatings. Conversely, ultra high temperature ceramics, and in particular HfB2, are among the best oxidation resistant materials known. A coating made of a HfB2/SiC composite (20% weight SiC) was tested as an oxidation protection on a Cf/SiC composite.
CHARACTERIZATION TECHNOLOGIES FOR PHARMACEUTICAL MELT EXTRUSION
Pharmaceutical melt extrusion has attracted much attention recently due to broad applications such as bioavailability enhancement, controlled release and taste masking. This article summarizes the characterization methods utilized in the field of pharmaceutical extrusion, and focuses on three applications: characterization of solid dispersion, process analytical technology (PAT) and solubility measurement of drugs in polymeric materials
ISOTHERMAL GROWTH RATES OF NODULAR AND SPHERULITIC STRUCTURES OF ISOTACTIC POLYPROPYLENE
A comparison between individual spherulites growth rates and circumferential nodular growth rates for isotactic polypropylene crystallized from the melt was conducted by means of polarized optical microscopy. The obtained results show that both spherulites and nodules grow linearly with approximately similar growth rates at high crystallization temperatures, while individual spherulites grow a little faster at lower crystallization temperatures.
ANALYSIS OF CFC AS ITER DIVERTOR PROTECTOR
Exposure of the carbon fibre composites (CFC) NB31 and NS31 by multiple plasma pulses has been performed at the plasma guns MK-200UG and QSPA. Numerical simulation for the same CFCs under ITER type I ELM typical heat load has been carried out using the code PEGASUS-3D. Comparative analysis of the numerical and experimental results allowed understanding the erosion mechanism of CFC based on the simulation results. A modification of CFC structure has been proposed in order to decrease the armour erosion rate.
THE EFFECT OF POLYBUTYLENE ON SEAL STRENGTH OF EVA/POLYBUTYLENE SEAL BLENDS IN MEDICAL DEVICE PACKAGING
Packaging seals must be both easily opened and strong enough to maintain integrity. To tailor the strength of Ethylene Vinyl Acetate (EVA) seal layers, Polybutylene (PB-1) is often added. This study examines the effects of seal layer composition, gauge, and sealing temperature on seal strength. A composition and structure/property map for EVA/PB-1 sealant layers was developed. This work helps provide an understanding of material origins of seal strength, so that strength may be easily tailored.
TOWARDS THE UNDERSTANDING OF FIBER TEAR
This paper presents the results of an experimental study into the mechanisms of fiber tear as it affects blister packaging for medical devices. Physical and chemical characterizations of different paper/film combinations were carried out. Results show hat fiber tear is largely due to the extent of mechanical interlocking of the paper fibers with the adjoining film. Suggesting hat the chemistry on each paper surface can further assist in influencing the extent of mechanical interlock observed.
RECYCLING OF POLYVINYL BUTYRAL (PVB) FROM LAMINATED SAFETY GLASS
Polymeric interlayers like Polyvinyl Butyral (PVB) - films between glass sheets make it safe in case of breakage. But, in the case of recycling, the adhesive interlayer makes the laminated glass difficult to cut. Fortunately, the mostly used PVB is a polymer which can easily been solved in different agents. Using this possibility the present investigations show that recovered PVB can be used in laminated safety glass again.
VISCOELASTIC BEHAVIOR OF HYDROPHOBICALLY MODIFIED HYDROGELS
The viscoelastic behavior of physically crosslinked copolymer hydrogels synthesized from N, N-dimethylacrylamide (DMA) and 2-(N-ethylperfluorooctane sulfonamido) ethyl acrylate (FOSA) is discussed. These gels have a core-shell nanodomains structure that is responsible for the crosslinks. High modulus (80 – 130 kPa), elongation (1000 – 1600 %), a tensile strength ~500 kPa and toughness (4 – 6 MPa) were achieved. The exceptional properties are due to the reversible nature of the physical crosslinks and their ability to dissipate energy.
HIGH FLOW THERMOPLASTIC POLYESTERS
A rapid extrusion process has been developed to make high flow polyesters in a melt reaction with a primary alkyl amine. In addition to much higher flow the modified resins show slightly faster crystallization but with reduced impact. This process has also been used to make high flow fiber glass filled PBT. It provides a low cost, fast option to make a wide variety of high flow resins from one staring material.
TROUBLESHOOTING BLACK SPECKS AND COLOR STREAKS IN INJECTION MOLDED PARTS
Black specks and color streaks in injection molded parts can reduce the yield and profitability of an injection molding process. This paper presents some of the common root causes for black specks and color streaks, and the technical solutions to remove them. Three case studies are presented.
THE CHARACTERISTICS OF IMMISCIBLE POLYMER BLENDS WITH MWNT
The electrical, rheological properties and phase behavior of multiwalled carbon nanotube (MWNT) filled with Polypropylene(PP)/Polystyrene(PS) blends were investigated. Based on the matrix polymer, two kinds of masterbatch chips were used to prepare ternary blends, and the influence of the kinds of masterbatch were confirmed on the phase morphology of ternary blends and the distribution of MWNT in ternary blends.
REVIEW OF ATMOSPHERIC PRESSURE PLASMA EFFECT ON THE ACTIVATION OF PLASTICS FOR IMPROVED ADHESION
Atmospheric pressure plasma treatment is a key process for surface preparation prior to adhesive bonding of plastics and composites. We observe >50% increase in bond strength and durability by using atmospheric plasma instead of traditional abrasion techniques. Surface analysis by XPS, IR and AFM indicates that the improved adhesion is due to carboxylic acid groups on polymer surface. The implications of this work for polymer adhesion will be discussed at the meeting.
AN IMPROVED FLOW CHANNEL DESIGN FOR FILM AND SHEET EXTRUSION DIES
A new flow channel design of die for polymer processing was devised. The design is based on the combination of two conventional die designs to take advantages of both types. The performance of the die with the new flow channel design was evaluated with a flow simulation. It was expected that the new die could obtain more uniform flow rate at the die exit than conventional dies without losing other performances such as residence time.
ENHANCEMENT OF MELT ELASTICITY OF LONG-CHAIN BRANCHED POLYETHYLENE BY BLENDING A LINEAR POLYETHYLENE
The rheological properties are studied for binary blends composed of a long-chain branched polyethylene and a linear polyethylene. It is found that the blends containing a linear polyethylene with high shear viscosity exhibit enhanced elasticity in the molten state, which is attributed to the prolonged relaxation time for entanglement couplings between a linear polymer and a branched polymer.
CHARACTERIZATION OF TENSILE PROPERTIES OF FUSED DEPOSITION MODELLING PROCESSED ABS MATERIAL
This paper presents the tensile properties of ABS parts fabricated by Fused Deposition Modeling rapid prototyping process. The mechanical behavior of FDM processed ABS parts for engineering applications is dictated by the FDM process parameters. This paper characterizes the tensile properties of ABS parts considering process parameters such as air gap, raster width, raster angle and build orientations. The tensile properties of FDM processed ABS parts are compared with that of injection molded ABS parts.
INVESTIGATION OF DIE DROOL PHENOMENON FOR LINEAR HDPE POLYMER MELTS HAVING IDENTICAL POLYDISPERSITY INDEX BUT DIFFERENT MZ AND MZ+1 AVERAGE MOLECULAR WEIGHTS
In this work, die drool phenomenon, for two linear HDPE polymers having identical polydisperzity index (Mw/Mw) but different Mz and Mz+1 molecular weight averages, has been investigated experimentally. It has been revealed that increase in linear HDPE chain length promotes the die drool phenomenon and vice versa.
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