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
Solid-State Polyimide Foaming from Powder Precursors: Effect of Particle Morphology on the Diffusive Phenomena
Solid-state foaming of polyimide powder precursors is studied by examining concurrent and competitive phenomena that determine the morphology and physical properties of the foam unit cell. Effects of particle size and shape on bubble nucleation and growth will be addressed.
Porous Polystyrene Foam Produced at Supercritical Conditions
This work examines four polystyrene (PS) resins and PS resins with fillers. The materials .are processed into sheets and then the sheets are foamed at various supercritical conditions. The morphology of foam is studied and a large porous PS foam is also developed for a vacuum insulation panel.
Effects of CO2 Content on the Expansion Behaviors of PS Foams
This paper discusses the effects of the blowing-agent content on the expansion behaviours of PS foams blown with CO2. Three groups of interchangeable filamentary dies were used to investigate the effect of the die geometry on the expansion ratio. A high CO2 content would be favourable to increase the expansion ratio. But the high CO2 content increased the solubility pressure and the amount of premature cell growth. When the amount of premature cell-growth exceeded a critical value, the expansion ratios were dramatically decreased, even at the optimum temperature.
Entrained Gas Process for Injection Molding
Entrained gas for injection molding, such as structural foam, microcellular foam, gas assist processing, has some common technical issues and safety concerns which are important to be fully understood for a safety system, and acceptable processing conditions. Several major issues are addressed and analyzed for machine and mold design, part design and handling.
Effects of Incorporating Recycled HDPE to Virgin HDPE and LDPE to Produce Tubular Film
This work presents the effects of incorporating post-consumer and post-industrial recycled HDPE to their virgin counterparts and to LDPE in different contents to produce tubular film for packaging. Tensile, surface and optical properties for each blend were measured.A reduction in the HDPEs blends physical properties and an increment in those of the LDPE/recycled HDPE blends were obtained as the recycled HDPE component was increased.
Nylon 66 - Maleated EPDM Polyblends
Nylon 66 was blended with maleated EPDM containing 0.5% of maleic anhydride. At 25% of maleated EPDM, impact strength increased 8-fold. On the other hand, modulus, strength, and DTUL decreased. The data suggested that the blend was too miscible, and might be improved by decreasing the maleic anhydride content to enhance phase separation.
Short Fiber Glass Reinforcement of Ductile Resins
In three ductile resins, polyphenylene ether sulfone (PPSU), a polycarbonate-acrylonitrile butadiene styrene (PC-ABS) blend and polycarbonate-polybutylene terephthalate blends (PC-PBT) use of a fiberglass coating that has little adhesion (non-bonding) to the resin matrix give superior impact strength compared to a traditional fiber coating with good matrix adhesion. The non-bonding glass gives reduced flexural and tensile strength but has comparable modulus to the traditional glass fibers with good matrix adhesion.
A Study on Processing and Characterization of Short Glass Fiber Reinforced ABS/Nylon 6 Blends
The properties of short glass fiber reinforced poly(acrylonitrile-butadiene-styrene)/Nylon 6 (ABS/PA6) blends were studied using the interfacial adhesion approach. Work of adhesion and interlaminar shear strength values were calculated from experimentally determined interfacial tensions and short beam flexural tests. APS was selected as the coupling agent for the glass fibers because of its compatibility with PA6. Increasing wt% of the PA6 in the short glass fiber reinforced blend increased the tensile strength and tensile modulus.
Compounding Order and Mechanical Properties in PP/PE/Talc Compound
Inorganic fillers are widely used to improve various properties of polymer materials. The dispersion of inorganic filler would undeniably influence the mechanical properties of a polymer compound. This paper describes the effect of the compounding order on mechanical properties of the PP/HDPE/Talc compounds which were prepared by changing the compounding order during the polymer compounding process. Consequently, the bending modulus and the impact strength of compound was improved, compared to that of general compounding.
Influence of Type of Filler on Natural Rubber Properties
Natural Rubber compounds with 15 phr filler (silica, wood flour and carbon black) were evaluated. Maximum torque, modulus, hardness and compression set increased when filler was present. Scorch time and curing time were also increased. A good reinforcement effect on the NR vulcanizate was observed when silica was used. There seemed to be very little influence of filler nature and particle size on properties studied; therefore, woodflour appears as an alternative and environment friendly filler.
The Performance of Polyvinyl Chloride / Thermoplastic Polyurethane Blends
Two grades of thermoplastic polyurethane (TPU), one polyester and one polyether based, were blended with two grades of PVC with different K-values of 56 and 71. Mechanical analysis showed that impact strength and elongation at break improved significantly, and the tensile and flexural modulus decreased with progressive increase in TPU content. DMTA results suggested partial miscibility between the two polymers. The performance of the blends was shown to be more dependent on the PVC/TPU percentage content rather than the PVC or TPU type.
Steel Wire Reinforced Plastic Composite Pipe
Steel wire reinforced polyethylene composite pipelines are a new technology product. The system is used for transport of oil, water, gas, and chemicals. This paper explains its new design concepts including micro-mechanics of load sharing and stress transfer. Recent test results will be reported to bring out its advantages over common plastic pipe and steel pipe.
The Effects of High Stress and Material Constraint on the Fracture Appearance of a Polyethylene Liner Pipe
This study involves a failure analysis on polyethylene liner pipes that had been installed as a corrosion protection liner in a high-pressure steel pipeline, operated at pressures up to 1500 psig. The peculiar fracture surface features are attributed to the stresses applied in service and to the geometry of the host pipe. The field failure times correlated extremely well with the published stress-rupture performance of the material.
POLYTRAC© Full Traceability in PE Valve Manufacturing
The Who, What, When and Where of every manufacturing process is critical to the longterm performance of polyethylene (PE) valves in natural gas distribution service. To obtain and archive this knowledge about every process, Kerotest developed POLYTRAC©, a full forward and backward traceability program for the POLYBALL™ line of PE ball valves. With full traceability, one has the maximum assurance that all manufacturing processes are under control and the highest quality valve is being produced.
Modeling of Mixers for Polymer Processing
The heat transfer in a batch mixer was studied using experiments and simulation. The mechanical torque was measured experimentally. The dissipated power was calculated and compared with the simulation. The heat transfer coefficient from experiment was calculate by a lumped approximation and compared with the data from simulation. The transient temperature profiles were obtained and the temperature distributions in the nip between rotors and barrel wall were shown.
Numerical Analysis of Cable and Wire Coating: Interactions between Material Rheology, Flow Domain and Process Conditions
Wire coating, based on the drag flow is a well-known process in the cable, wire or fibre-optic industry. It has been studied extensively in experimental and computational form over recent years. During the coating a polymer melt flows through an annular converging die and then meets a wire or cable that is usually traveling at high speed. This study is concerned with the numerical simulation of the complex flows that arise in the coating system with a thermoplastic polymer. The simulation study was performed in order to better understand the influence of the rheology parameters, the chosen processing conditions and the coating die geometry dimensions.
Measurement of Interfacial Instabilities during Coextrusion of LDPEs in Flat-Dies
This paper presents the results of some coextrusion flow studies for flat film on feed-block and multi-manifold flat dies for well characterised LDPE resins. The aim is to gain a better understanding of interfacial instability phenomena. The LDPE resins included materials of high and low viscosity as well as broad and narrow molecular weight distribution. The experiments involve the coextrusion of either the same materials in both layers or various combinations of materials with different viscosities. The focus of the work was to evaluate the effects of flow rate, viscosity and other material characteristics on the interfacial instabilities. The results from these experiments showed a possibility to locate areas where low or high frequency instabilities were created.
Compensating for Die Swell in the Design of Profile Dies
Because of the effects of die swell, the final shape of an extrudate is often substantially different from that of the exit opening of the die. As a result, the design of profile dies producing complex shapes often involves more than just “balancing” the die but also compensating for the effects of die swell. Typically, a successful design of such dies is only achieved through much “cut and try”. However, with the use of a fully three-dimensional finite element flow algorithm along with quick mesh generating capabilities, the usual cut and try involved in the design of many profile dies can be greatly reduced if not eliminated.This paper demonstrates how the effects of die swell can be compensated for in the design of profile dies. For profiles with one plane of symmetry, this includes compensating for the sideways translation of the extrudate as well as the change in shape that the extrudate experiences. Completely asymmetric profiles undergo a “twisting” downstream of the die. This twisting, which appears not to have been reported in the literature (at least for isothermal extrusion) is also accounted for here along with the change in shape that the extrudate undergoes.
Real-Time Estimation of Crystallization Half Time during Blown Film Extrusion and its Influence on Final Film Properties
The development of crystallinity during film blowing of a linear low-density polyethylene at different processing conditions has been investigated using online Raman spectroscopy. The obtained trends for crystallization rates were explained using the concept of flow-induced crystallization. Further, direction dependent (machine and transverse) tensile properties were studied as a function of take-up ratio (TUR), inflation air pressure and cooling conditions. Based on the results for development of crystallinity at different conditions, the reciprocal crystallization half time was suggested as a likely essential parameter to formulate processing-structure-property relationships.
Stability and Nonlinear Dynamics of Film Blowing
Transient behavior and stability of the film blowing process have been studied using the governing equations consisting of two well-known force balances and a Phan- Thien and Tanner constitutive equation. A newly-devised numerical scheme, which incorporates an orthogonal collocation on finite elements, was employed to yield transient solutions of the film blowing operation which are hitherto difficult to obtain due to severe numerical stability problems when the system is in an instability called draw resonance. Thus obtained simulation results make possible more systematic analysis of draw resonance, e.g., draw resonance criterion based on the traveling times of kinematic waves on the free surfaces, and the effects of fluid viscoelasticity on the stability.
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