bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acrylic process aids for PVC: From theoretical concepts to practical use
Authors: Disson Jean‐Pierre , Girois Stéphane 
Published: April 2004

AbstractAcrylic process aids have been widely used for decades in the production of both rigid and flexible PVC materials. Their advantages are well‐known and are briefly reviewed in this paper. Excessive use of process aids or selection of the wrong molecular weights may, however, lead to undesirable behavior ultimately resulting in defects in PVC materials. These limitations are discussed in detail and explained on the basis of general polymer science considerations. Some criteria to optimize the proper selection of the level and nature of the process aids in PVC formulations are given in relation to the final applications, such as films, window and foam profiles, pipes, and so on.
Effects of process temperature on the weathering performance of rigid poly(vinyl chloride)
Authors: Zehner Burch E. , Hartley Jeff 
Published: April 2004

AbstractElevated process temperatures can accompany current high extrusion rates of rigid poly(vinyl chloride). Various colored weatherable siding compounds were studied in the processing temperature range of 193°C to 227°C. The extruded compounds showed only minor color shifts due to increased melt temperatures. Outdoor exposure through four years in Arizona, Florida, and Ohio demonstrated typical color change but did not exhibit significant color shift relating to the initial processing temperatures. The samples extruded at elevated melt temperatures did demonstrate reduced impact strengths prior to outdoor exposure. Florida‐exposed and Ohio‐exposed samples lost impact strength throughout five years of exposure, with the samples processed at higher temperatures continuing to show lower impacts over time.
The influence of flame retardant structure on UV stabilization approaches in polypropylene
Authors: Gray Robert L. , Lee Robert E. , Sanders Brent M. 
Published: April 2004

AbstractUV stabilization of polypropylene fiber containing brominated flame retardants has been the focus of intense technical efforts with only limited success. Acid generated by the flame retardants deactivates HALS, thus severely reducing the HALS' effectiveness. Because of this interaction, flame retarded polypropylene fiber has been generally restricted to applications requiring little or no UV stability. Evaluation of structure‐performance characteristics of both flame retardants and stabilizers allow development of packages which optimize processability, flame retardancy, and UV stability. This paper reviews progress in the stabilization of flame retarded PP fiber and presents new advances in this field.
An introduction to toughened polyamide‐4,6
Authors: Harding Jeff A. 
Published: April 2004

AbstractImpact modified polytetramethylene adipamide (polyamide‐4,6) has recently been introduced. The author compares this compound to a toughened polyamide‐6,6 and a toughened polyamide‐6 in selected impact resistance and elevated temperature tests. Based on the results, toughened polyamide‐4,6 promises similar impact strength; and, better retention of stiffness, creep modulus, and toughness at elevated temperatures. Apparent improvements in melt stability make it suitable for extrusion, as well as injection molding applications.
Impact‐modified poly(vinyl chloride) and methyl methacrylate copolymer blends. Part 2: Thermal‐mechanical properties
Authors: Burke Dennis Michael 
Published: April 2004

AbstractThe objectives of this study were to determine the compatibility of various blends of commercially available rigid, unplasticized, impact‐modified polyvinyl chloride (UPVC) and methyl methacrylate (MMA) copolymers. The effects of acrylic type and loading level on compatibility were investigated. The resultant alloys or blends were subsequently evaluated for compatibility through examination of the following properties: processability, rigidity, strength, impact resistance, heat resistance, clarity, and ultra‐violet aging. This report limits itself to the discussion of the thermal‐mechanical properties, specifically dynamic mechanical properties in torsion (ASTM D 5279).
The role of lubricants in rigid PVC foam processing
Authors: Decker Robert W. 
Published: April 2004

AbstractThis study is designed to evaluate the role that lubricants have in the processing and final cell morphology of extruded rigid PVC foam. By developing a standard formulation in which only the type of lubricant was varied, the direct effects of functionality of the lubricant could be observed. It was found that not only is lubricant type very important for ease of processing, but also it determines the effectiveness of the blowing agent and the final density of the foamed material.
New rigid vinyl compound molding technology
Authors: Summers James W. , Toyoda Paul , Weir Scott , Beal Chris , Toensing Carl 
Published: April 2004

AbstractDuring injection molding, it is not uncommon for shear heating to cause localized temperatures exceeding 300°C. This heating, if not suppressed, can cause vinyl degradation. Three main factors influence shear heating. They are (a) mold design, especially restrictions such as small gates; (b) injection conditions, especially injection velocity; and (c) compound viscosity. To address the compound factor, two new vinyl compounds have been created for custom injection molding, which are especially designed to suppress the shear heating temperatures. Geon® M3700 has good impact at room temperature, and Geon® M3800 has outstanding impact at room temperature and at low temperatures. These compounds use a new technology that produces a balance of properties never before achievable. These innovative compounds show enhanced processability including improved static thermal stability, improved shear stability, tolerance of higher injection screw rpms, tolerance of higher injection speeds, the ability to mold at lower injection pressures, reduced molding cycles, and the ability to fill thin part walls. Also designed into the compounds are improved color fastness during exposure to light, improved appearance, and reduced corrosiveness. Other properties such as impact strength, tensile strength, modulus, heat deflection temperature, hardness, UL flammability rating, specific gravity, and mold shrinkage remain comparable to older technology.
Fatigue crack propagation and damage evolution in PBT‐GF and SAN‐GF
Authors: Pavšek Vojko , Ehrenstein Gottfried W. 
Published: April 2004

AbstractOur earlier investigations of fatigue behavior in PBT‐GF and SAN‐GF with different fiber lengths have shown that fatigue crack propagation (FCP) can be described in terms of elastic‐plastic fracture mechanics. In this work it is shown that the influence of structural material parameters on the resistance to FCP correlates with the extent of energy dissipation at the crack tip. With increasing fiber length, the zone of energy dissipation is increased. By means of microscopic investigations, the prevailing damage in the zone of energy dissipation is identified as micro cracks in the matrix.
The determination of polymer additive effects in a spherilene process HDPE matrix upon water carry‐over in water quenched, cast film extrusion
Authors: Cowell Timothy J. , Brunner Clayton B. 
Published: April 2004

AbstractA test method useful in determining the effects of polymer additives upon water carry‐over (WCO) in water quenched, cast film extrusion is presented. Data from this test is obtained on film specimens based in a Spherilene process HDPE resin individually doped with 250 and 500 ppm of six various primary and secondary antioxidants and acid scavengers. Water contact angles and film surface tension data is also presented. The WCO test is reproducible and data may be applied to commercial production. Different additives that carry out the same function in the polymer may have greatly varying WCO properties; these differences are not detected by equilibrium goniometry.
“Go with the flow!”: Advantages of high melt flow rate ignition resistant polycarbonate vs. IR PC/ABS blends
Authors: Ogoe Samuel A. , Grelle Peter F. , Watkins Thomas J. , Masloski Peter J. , Kallman Mark A. 
Published: April 2004

AbstractPolycarbonate (PC) has some inherent ignition resistant (IR) characteristics with good physical and mechanical properties. However, polycarbonate resins are not as easily processed as some styrenic materials, because of the high viscosity of PC. Extensive studies have been performed to develop an easy flow (high MFR) ignition resistant polycarbonate (IR PC) resin rated UL‐94 of V‐O down to 1.6 mm (0.0625 in) thickness and 5V down to 3.2 mm (0.125 in) thickness. This unique high MFR polycarbonate resin contains reduced levels of IR additives, in comparison to standard IR polycarbonate resins, which help to maintain the physical and mechanical properties of the polycarbonate base resin, without sacrificing the flammability properties of the final product. Using a high MFR polycarbonate resin improves processability and minimizes possible thermal degradation, resulting in improvement of overall processing performance and cost.
The influence of plasticizer on extruded thermoplastic starch
Authors: Van Der Burgt M. C. , Van Der Woude M. E. , Janssen L. P. B. M. 
Published: April 2004

AbstractThis paper describes the use of an extruder for the plastification process of potato starch with glycerol and water as plasticizers. The influence of both plasticizers is expressed in the water absorption index (WAI) and water solubility index (WSI). The amount of water added prior to extrusion is a tool to protect the starch polymers from degradation and to improve the extruder performance.
Weathering performance of rigid PVC pigmented with iron‐containing pigments: The relationship between weathering and the chemical nature of the iron contained
Authors: Peake Geoffrey T. 
Published: April 2004

AbstractWeathering performance of rigid PVC pigmented with iron oxide or some complex inorganic pigments (CIP) containing iron can be poor. Consideration of iron‐containing CIP's for use in exterior PVC leads to the common question: “How much ‘free iron’ is present in the pigment?” It has been unclear what “free iron” means and therefore difficult to know which iron‐containing pigments will weather well and which will not. Some formulators may avoid iron‐containing pigments altogether by electing not to formulate in a color space only achievable with those pigments. We compare the weathering performance of a series of iron‐containing CIP's to the amount of iron contained, the crystal phases, and the amount of acid‐extractable iron. We see a strong correlation between the weathering performance and the extractable iron content. Many iron‐containing pigments have good weathering performance in PVC, so one shouldn't exclude iron‐containing pigments from consideration based solely on the iron content. The acid‐extractable iron is an indicator of the expected weathering performance. Careful evaluation and selection of pigments may allow consideration of previously avoided pigment combinations.
Requirements for medical vinyl compounds
Authors: Rakus Julius P. 
Published: April 2004

AbstractWhat makes a material suitable for applications in the medical device industry? It is a question often asked, but seldom answered in a definitive way. This paper examines vinyl compounds from various viewpoints and attempts to define the requirements for their medical use with respect to formulation, chemical and mechanical purity, and performance characteristics such as viscoelastic properties, appearance, sterilizability, shelf life, and biological safety. Primary consideration is given to the situation in the United States, with a brief review of the position of some other countries' regulatory agencies. An outline is presented of how material suppliers can assure their customers and the regulators about the suitability of the compounds in question for various applications.
Characterization and properties of polyphthalamide/polyamide blends and polyphthalamide/polyamide/polyolefin blends
Authors: Desio Glenn P. 
Published: April 2004

AbstractPolyphthalamide(PPA)/polyamide(PA) blends were analyzed to determine the effect of PA addition to PPA on melting point, glass transition temperature, dynamic modulus, and heat distortion temperature. Results indicate that the choice of PPA and the choice of PA for the blend systems affects not only the above properties but also the miscibility of the blend systems. In general, PA addition to PPA lowers the melting point and glass transition, which potentially makes these blend materials easier to process. Also, the PPA/PA blends were observed to have dynamic modulus curves with transitions shifted to lower temperatures and crystalline plateaus shifted to lower modulus.PPA/PA/polyolefin(PP) systems were investigated to determine if a useful balance of properties could be obtained, even though the blend components would have to be processed at unusually high processing temperatures (in excess of 320°C). Morphological characterization indicates that small dispersed domains of PP are obtained. The modifiers utilized in these systems were either found at the interface of the PP domain or dispersed within the PP domain. The properties of PPA/PA/PP blends indicates that these systems are ductile and have a good balance of strength, stiffness, impact, and thermal performance.
Processing‐morphology‐property relationships in polyethylene/acrylonitrile copolymer/compatibilizer blends
Authors: Shah M. , Jabarin S. A. 
Published: April 2004

AbstractEffects of blend composition, compatibilizer, and processing conditions on the morphology, rheology, and mechanical properties of the ternary blends are investigated. Introduction of compatibilizer and increasing shear rate lead to a finer particle dispersion. A modification of Wu's equation is utilized to obtain an estimate of the interfacial tension. The results indicate a reduction in interfacial tension upon addition of compatibilizer. Morphological stability of these blends is studied by reprocessing them in an injection molding machine and a twin‐screw extruder. The nature of the reprocessing history was found to govern the morphology and the mechanical properties of the blends investigated.
Low volatility antioxidants for scorch protection of polyurethane foams
Authors: Gray Robert L. , Lee Robert E. , Sanders Brent M. 
Published: April 2004

AbstractWork continues to be done to provide effective stabilization of flexible bun stock formulations required by the reduction of chlorofluorocarbon (CFC) blowing agents, the associated increase of water content, and increased exotherm. Butylated hydroxytoluene (BHT) has served well as an antioxidant. However, its high volatility and tendency to form highly colored by‐products have limited its versatility.
Recent advances in the stabilization of flexible and semirigid PVC
Authors: Burley Joseph W. 
Published: April 2004

AbstractBoth the European and USA markets for liquid mixed metal stabilizers have moved or are moving to cadmium‐free products. Self‐lubricating products now dominate demanding areas such as calendering and extrusion in the European marketplace while the USA market has produced higher efficiency products by other means. In both markets, the use of organic costabilizers has played a major role in the formulation of cadmium‐free products. The merits of self‐lubricating technology and a new class of patented pyrrolidines are discussed here.
Installing a color system: The people considerations
Authors: Becker Elaine F. 
Published: April 2004

AbstractThe introduction of low‐price color systems, both quality control and color formulation, has brought affordability and practicality to the medium and small plastics companies. While color systems today are faster, cheaper, more accurate, easier to use than ever before, they are not that much more successful at doing what they were designed to do than they were 25 years ago. The pitfalls of start‐up and implementation and the people problems have changed very little and are still a major factor in determining the degree of success. This paper discusses the ramifications of who is chosen to implement the system, what their charter is, and the resources that they are given. Factors to be considered and creating the right environment when implementing a color system are discussed. Some suggestions for planning a successful start‐up and installation are given.
Use of inert gases in extruded medium density polypropylene foams
Authors: Dey S. K. , Natarajan P. , Xanthos M. , Braathen M. D. 
Published: April 2004

AbstractCarbon dioxide gas was used as a physical blowing agent to produce medium density polypropylene foam sheets using a single screw extruder. The mechanical properties of the foam were similar in the machine direction and in the transverse direction. A better surface finish and a lower density foam was produced by using a commercial wrapping film as a cap layer. The process conditions and die design data are presented in an attempt to relate to product characteristics.
The reactions of stabilizers prior to the appearance of degradation in vinyl
Authors: Grossman Richard F. 
Published: April 2004

AbstractThe infrared spectra of simple allylic chlorides dissolved in a variety of primary stabilizers indicate a shift in the CC stretching frequency to higher energy. This suggests that in the presence of primary stabillizers, allylic unsaturation has less of an activating effect on chlorine. The initial effect of stabillizer addition, therefore, may be simply to increase the activation energy of degradation, and the first function of the vinyl stabilizer, that of a reverse catalyst of the degradative process.
The influence of acrylic impact modifiers on the weld strength of extruded rigid PVC
Authors: Weier Jane E. 
Published: April 2004

AbstractThe weld strength of a PVC window profile is a function of complicated interactions among many contributing variables. Major determinats of weld strength include the PVC formulation, profile processing conditions, and welding parameters. Impact modifiers enhance weld strength due to their well‐known effects on PVC mechanical properties. For modifiers having similar impact efficiency, the contribution to improved weld strength is maximized through optimization of the PVC viscosity and blend morphology at the weld line.
Relation of crystalline structure and mechanical properties of nucleated polypropylene
Authors: Pukánszky Béla , Mudra István , Staniek Peter 
Published: April 2004

AbstractFour heterogeneous nucleating agents were added to polypropylene (PP) homoblock and random copolymers. Melting and crystallization of the polymers were studied by differential scanning calorimetry (DSC), and characteristics derived from the crystallization exotherms were related to the mechanical properties of injection molded bars. A very close correlation was found between the crystallization characteristics and Young's modulus of the polymers. The general correlation proved to be valid for all three polymers studied and also for each nucleating agent. The developed empirical correlation makes possible the approximate prediction of stiffness from a simple DSC trace. Further study is needed to give the relationship better physical meaning and to extend it to other mechanical properties.
Nucleating agent effects on selected properties of polypropylene
Authors: Wong A. C‐Y , Leung W. W. M. 
Published: April 2004

AbstractA study of nucleating agent effects on the selected optical and mechanical properties of a semicrystalline homoisotactic polypropylene is presented. The results showed that the type and concentration of the nucleating agents to be added, and the screw speed during the compounding process, were of vital importance. It was also noticed that the improvement in optical clarity due to the addition of the additive might not necessarily benefit the mechanical properties of injection molded articles.
Effects of fiber orientation on strain concentrations in glass reinforced polyamides
Authors: Bernhardt Anne , Panzeri Giovanni 
Published: April 2004

AbstractOrientation of reinforcement fibers in injection molded parts is a key factor in determining their strength and stiffness: therefore stress‐strain analyses based on isotropic material models produce only rough results. We present a flow/strain analysis methodology that accounts for the actual anisotropic material properties and fiber orientation. Material properties are determined by experiment, fiber orientation is inferred from flow simulation results (velocity vectors). Stress/strain fields are calculated by means of finite element analysis. Results show that for notched parts molded from short glass reinforced polyamide resin, there is a significant dependence of the strain concentration on the local fiber orientation resulting from different injection molding conditions.
Volatiles released during the weathering of PVC
Authors: Carlsson D. J. , Krzymien M. , Worsfold D. J. , Day M. 
Published: April 2004

AbstractVolatile organic compounds and organochlorine species liberated by UV exposure of poly(vinyl chloride) (PVC) siding samples have been identified and preliminary quantification made. These volatiles included those remaining in a PVC sample after weathering or laboratory UV exposure and which could be released by thermal desorption. In addition, by using a flow‐through cell and granular carbon adsorbents, volatile species directly desorbed during laboratory UV exposure were measured. Total directly desorbed organochlorine compounds were about 1/20 of the weight of hydrogen chloride as measured by conductometric analysis, Quite similar products were observed from old (∼1984) and current (1995) commercial siding formulations. Observed volatile compounds are proposed to come from the TiO2‐controlled photo‐oxidation of both PVC and its additives such as impact modifiers.
Reversible discoloration effects in the photoaging of poly(vinyl chloride)
Authors: Gardette Jean‐Luc , Lemaire Jacques 
Published: April 2004

AbstractIt is often observed that the photochemical degradation of titanium dioxide pigmented PVC leads to a latent discoloration that is revealed only during a further period of storage of the aged material in the dark. This effect is reversible, and photobleaching can be provoked by a new irradiation of the polymer. This behavior can be attributed to the formation of polyenic sequences with a short conjugation length, which present an absorption below 400 nm. The screen effect of the pigment protects these polyenes against photooxidation, which permits these polyenes to accumulate in the degraded polymer. In the absence of light, these polyenes can be thermally isomerized, so leading to isomer forms absorbing at longer wavelength above 400 nm. This absorption is responsible for a yellowing of the polymer. The isomerization is perfectly reversible and a further irradiation provokes the conversion to the isomer form absorbing below 400 nm, leading then to a photobleaching of the sample. These experiments can be repeated many times before any distortion occurs.