bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emergency stopper for VCM suspension polymerization
Authors: Malmonge S. M. , Santos L. R. 
Published: April 2004

AbstractBecause of the exothermicity of reaction and the necessity of using active initiators for the vinyl chloride monomer (VCM) suspension polymerization reaction, a study was undertaken in order to choose the best polymerization inhibitor for emergency situations such as temperature runaway, power failures, and agitation system problems. The effect of triethylene glycol‐bis3(3 terc‐butyl‐4‐hydroxy‐5‐methyl phenyl) propionate (1) and N‐nitrosophenylhydroxylamine ammonium salt (2) cited in the literature as free radical polymerization inhibitors on VCM suspension polymerization reactions is shown.
Injection molding higher performance reinforced plastic composites
Authors: Rosato D. V. 
Published: April 2004

AbstractConventional screw plasticizing injection molding machines (IMM) have been used to mold over 50 wt% of all reinforced plastics (RP) composite processed (1–9). Principal reinforcement used is E‐glass of short glass fibers (SGF) with thermoplastics (TP) such as nylon (PA) and polypropylene (PP) (each over 25 wt% of total). Fiber lengths are usually limited to being milled to 1 mm (0.04 in); average length in molded parts are 0.3 mm (0.01 in) to 0.5mm (0.02 in); Long glass fibers (LGF) would be more desirable in obtaining better performances such as higher strength, stiffness, creep resistance, fatigue resistance and improvements in dimensional stability and thermal properties. However, fibers will degrade in length during conventional molding resulting in less efficient use of reinforcements. LGFs can start at 10 mm (0.4 in) and after IM can be in the order of at least 5 mm (0.2 in); longer fibers are also used. Special fiber impregnation techniques will permit successfully molding LGFs (1–21).
Polyolefin formulation validation using infrared spectrometric classification techniques
Authors: Van Every K. W. , Elder M. J. 
Published: April 2004

AbstractDiscriminant analysis using principal components of mid‐infrared spectral data is demonstrated as a powerful quality validation tool to augment sophisticated manufacturing processes where rigorous multicomponent analysis is not only costly but in many cases unwarranted. In order to balance competing requirements of validation, a multiple model approach is taken, which combines the best information available about the process, the chemistry and the spectroscopy of the formulation. A systematic approach to evaluate training data is discussed as a crucial step to insuring a diverse but homogenous calibration.
The effects of EPM long chain branching on TPO properties
Authors: Brignac Stephen D. , Young Harold W. 
Published: April 2004

AbstractIn this paper the effects of EPM long chain branching are examined in terms of reheological, processing, and physical property responses in mechanically blended TPOs. Morphological effects induced by this polymer variable as indicated by SEM are detailed as well. The EPMs used in this study were produced by DSM Copolymer, Inc., in Baton Rouge, Louisiana.
Effects of fillers on permeability and mechanical properties of HDPE blown films
Authors: Gill T. S. , Xanthos M. 
Published: April 2004

AbstractHDPE compounds containing various amounts of rigid (platy talc) or deformable (nylon‐6) oxygen barrier components were blended in a twin‐screw extruder and processed into thin films by blown film extrusion. The films were tested for oxygen permeability and mechanical properties and analyzed for morphology. Optimization of barrier component content is shown to depend on the desired permeability level, film ductility and processability.
Compatibilizer system for extruded polyethylene foam and film
Authors: Lee Shau‐Tarng 
Published: April 2004

AbstractThis paper discusses the processing/product benefits of adding additives to extruded polyethylene (PE) foam and film. Low‐density polyethylene foam (over 30 times expansion) requires adequate cooling to stabilize the melt/gas system for optimal foaming efficiency. The presence of a small portion of high melting polyethylenes (i.e. LLDPE, HDPE) causes flow instability after cooling, resulting in surface defects in finished products. We found that the addition of metal oxide and fatty acid ester improved processing latitude and foam product quality. This formula was also tested in film processes at various ratios of LD/LLD/HD with promising results. It appears that this formula can allow us to accommodate post consumer resin (PCR) and to take advantage of PE price variations.
Recent research advances in the chemistry of poly(vinyl chloride)
Authors: Starnes William H. 
Published: April 2004

AbstractSummarized briefly here are some new observations that relate to the polymerization chemistry of vinyl chloride (VC) and to the thermal degradation, thermal stabilization, fire retardance, and smoke suppression of poly(vinyl chloride) (PVC). During polymerization, head‐to‐head VC emplacement leads to β‐chloroalkyl radicals that can transfer chlorine atoms directly to VC. Another mechanism for transfer to monomer is responsible, however, for the polymer molecular‐weight reductions that occur at high VC conversions. This transfer process involves the abstraction of methylene hydrogen from the polymer by an ordinary macroradical and the subsequent bimolecular donation of a chlorine atom to VC. The propagation steps of the polymerization do not become diffusion‐controlled at VC conversions near 90%, and hydrogen abstraction from the polymer by ordinary macroradicals leads to the structural defects that cause thermal instability. The thermal dehydrochlorination of PVC involves ion pairs or four‐center concerted transition states that are highly polarized. Reversible thermal stabilization of the polymer by organic metal salts occurs by the Frye‐Horst process, and the reductive coupling of PVC chains may suppress both smoke and flame. This coupling can result from reactions of the polymer with zero‐ or low‐valent transition‐metal species that are formed in situ from appropriate additives.
Poly(vinyl chloride) polymerization performance‐enhancing initiators with emphasis on high activity grades and water‐based dispersions
Authors: Zimmermann Heinz 
Published: April 2004

AbstractVinyl chloride is most commonly polymerized by suspension processes, where surface active materials as granulating agents and organic peroxides as free radical initiators are the crucial additives, which may affect PVC qualities substantially. Among the wide variety of usable and commercially available organic peroxides, the most suitable types for an individual process need to be selected with specific regard to reactivity, polymerization performance, storage, and handling. Currently, high activity types are subject of continuously growing interest to many PVC manufacturers who are trying to achieve higher productivity and to expand their product range mainly by focusing on PVC grades of higher molecular mass. A short comparison between the different alternatives of highly active initiators is given, showing the potential for further improvement by using a new difunctional peroxyneodecanoate. Among the manifold formulations of organic peroxides, which have been developed, particular importance is attached to water‐based grades. Dispersions of solid peroxydicarbonates are explained in detail, and their outstanding benefits on performance and safety are covered.
Foamed rigid vinyl for building products
Authors: Schipper Peggy S. , Black Janine , Dymek Tony 
Published: April 2004

AbstractPVC foamed building products have seen good growth lately because of their favorable properties and economics. Continued good growth is seen for the future. Expanding application areas, especially in the U.S. market, have created a need for knowledge on formulation and processin prarameters. Application areas are explored as well as raw material considerations, processing methods and parameters, and final physical properties.
An alternative to DEHP plasticized polyvinyl chloride in chemotherapy drug delivery systems
Authors: Czuba Len , Puryear Harry , Sarkar Kamal 
Published: April 2004

AbstractMedical plastic selection has recently been challenged with the development and approval of a new chemotherapy drug that, because of the carrier solution used, causes extraction of di‐2‐ethylhexyl phthalate (DEHP) plasticizer from commonly used polyvinyl chloride (PVC). There is much discussion as to whether or not this extraction is a problem. However, in an effort to comply with the recommendations of the drug manufacturer, many device companies are in the process of converting their devices from DEHP plasticized tubing to tubing made with non‐phthalate plasticizer. This paper describes the effort made to both understand and comply with the recommendations made by the drug manufacturer. The testing confirms effective reduction of the phthalate plasticizer extraction.
A study of the synergism of poly(vinyl chloride)/polyether‐ester blends
Authors: Ellis Candace L. , Barry Carol M. F. 
Published: April 2004

AbstractThe synergism between blends of poly(vinyl chloride), PVC, and a polyether‐ester elastomer, COPE, was investigated. Previous research indicated that blends of these two polymers produced synergistic results in the melt index and Izod impact properties of the system. This research confirmed the increased flow properties of the blends using melt index, capillary rheometer, and dynamic mechanical analysis. The synergism was found to be shear rate dependent and an additive relationship was approached at high shear rates. Differential scanning calorimetry showed that the blends were immiscible. This suggested that phase separation was the cause of the synergism in the flow properties and that elongation of the COPE domains most likely produced the shear rate dependency of the blend synergism. The phase separation would also have produced the improvement in the Izod impact properties of the blends.
Extrusion of polypropylene foams with hydrocerol and isopentane
Authors: Behravesh Amir H. , Park Chul B. , Cheung Lewis K. , Venter Ronald D. 
Published: April 2004

AbstractAn experimental investigation was conducted to research the cell nucleation behavior in the extrusion foam processing of polypropylene (PP) using hydrocerol and isopentane. While the hydrocerol and isopentane are considered to function as the nucleating agent which determines the cell‐population density and as the blowing agent to control the volume expansion ratio respectively, both agents affected the cell‐population density. In addition, synergistic effects of these agents on the cell density were observed. In foam processing with hydrocerol, a higher cell‐population density was noted at lower processing pressures and at higher polymer flow rates. This phenomenon is of interest since the cell density, in general, increases as the processing pressure increases when only a physical blowing agent is used in the foam processing. The experimental results indicate that the nucleation in the foam processing with hydrocerol is governed by a heterogeneous nucleation mechanism; also, the quality of the mixing of the polymer and the agents, as well as the amount of gas lost during the plastication of the pellets in the barrel, exerts a strong influence on the resulting cell density.
Dynamic mechanical properties of lightly sulfonated polystryrene ionomers
Authors: Calhoun Bret H. , Moore Robert B. 
Published: April 2004

AbstractThe effects of counterion type and addition of plasticizers on the dynamic mechanical properties of sulfonated atactic polystyrene (SaPS) containing 2.1 mole percent ionic groups have been investigated. For SaPS neutralized with alkali metal counterions at temperatures below 180°C, the matrix Tg and elastic modulus were not significantly affected by counterion type. However, above 180°C, the breadth of the rubbery plateau significantly decreased with increasing counterion size. Neutralization of SaPS with alkyl ammonium counterions decreased both the matrix Tg and the breadth of the rubbery plateau with increasing counterion size. By incorporating an ionic plasticizer in Na+ neutralized SaPS, dynamic mechanical properties were observed to be intermediate of systems neutralized with the alkali metal and alkyl ammonium counterions.
Thermal stimulated current study of core‐shell impact modifier/PVC blends
Authors: Li Kuo‐Chen , Tang Kuo‐Chang , Lee Juh‐Shyong , Chao Cheng‐Lung , Chang Ren‐Kuen 
Published: April 2004

AbstractThis study examines the efficacy of core‐shell structure impact modifers, having different particle sizes and core/shell compositions, for modifying PVC's impact strength. The core and the shell's main compositions are polybutyl acrylate and polymethyl methacrylate, respectively. Also, the TSC is used to obtain the fundamental states of the blended impact modifier/PVC systems, thereby allowing them to be correlated to the above observed efficacy. Results of this study can provide valuable information toward exploring the feasibility of using the TSC data as a product development guide for designing PVC impact modifiers.
Successful extrusion of small diameter CPVC pipe
Authors: Grohman Martin , Holloway Scott 
Published: April 2004

AbstractChlorinated polyvinylchloride (CPVC) pipe is a rapidly growing market, especially 25.4 mm (1″) pipe and smaller. Extrusion of CPVC pipe presents a greater challenge than PVC, because CPVC has less heat stability and higher viscosity. However, CPVC has good physical properties, particularly with respect to heat, and can be used to make hot water pipe. This paper discusses some of the basic factors involved in screw and pipe head design for CPVC extrusion, and gives some examples of successful applications.
The effect of zinc borate in combination with ammonium octamolybdate or zinc stannate on smoke suppression in flexible PVC
Authors: Ferm Donald J. , Shen Kelvin K. 
Published: April 2004

AbstractThe effect of combinations of zinc borate with ammonium octamolybdate or zinc stannate on smoke suppression upon combustion of flexible PVC was studied. Effects on Oxygen Index and on residual char after ten minutes at 560°C were also evaluated. These studies were done using both a conventional dioctyl phthalate (DOP) plasticizer and a mixed plasticizer consisting of a 1:1 combination of DOP and an alkyl aryl phosphate ester. For both plsticizer systems, results showed that combinations of the zinc borate with either ammonium octamolybdate or zinc stannate gave an improved effect with respect to smoke reduction upon combustion. Thermogravimetric analysis (TGA) of PVC containing these additives showed no indication of interactions to explain this effect. TGA analyses indicated that PVC samples made with the mixed plasticizer had final decompositon temperatures which were slightly higher than those made with DOP as the plasticizer.
Photolysis of dialkyl phthalates and poly(vinyl chloride) plasticized with dialkyl phthalates at wavelengths exceeding 290 nm
Authors: Balabanovich A. I. , Denizligil S. , Schnabel W. 
Published: April 2004

AbstractWhen dialkyl phthalate plasticizers, neat poly(vinyl chloride), PVC, and PVC plasticized with dialkyl phthalate are subjected to near UV radiation at λinc > 290 nm, chemical alterations are induced by traces of impurities capable of absorbing light in this wavelength range. The main photoproducts formed in the case of neat phthalates are olefins, alcohols, and phthalic acid anhydride. Neat PVC undergoes CCl bond cleavage and, in addition, carbonyl and polyene groups are formed. The formation of carbonyl groups is a nonlinear (auto‐accelerated) process whereas polyene generation occurs linearly with increasing irradiation time. The photolysis of phthalate‐plasticized PVC is characterized by the decomposition of the plasticizer, evidenced by the decrease in the absorption band at 278 nm, and by the formation of carbonyl groups attached to PVC and the cleavage of CCl bonds as evidenced by the increase or decrease in the IR absorption bands at about 1710 and 617/639 cm−1, respectively. Phthalates hardly influence the incorporation of carbonyl groups into PVC (an auto‐accelerated process) and retard only slightly the cleavage of CCl bonds. By contrast, phthalates sensitize the incorporation of carbonyl groups upon irradiation at λinc = 254 nm. Within the error limit no effect of the chemical nature of the phthalate on the formation of photoproducts was detectable upon performing irradiations at λinc > 290 nm.
The properties of glass fibers recycled from the thermal processing of scrap thermoset composites
Authors: Kennerley J. R. , Fenwick N. J. , Pickering S. J. , Rudd C. D. 
Published: April 2004

AbstractGlass fiber reinforced composites can be recycled by combustion of the polymer in a fluidized bed and reclamation of the reinforcement. The effect of heat on the reinforcing properties of glass fibers was studied by measuring the strength of a composite incorporating heat cleaned glass cloth. This work was then extended by measuring the tensile strength of single fibers. An initial study of the residual strength of fibers processed in a fluidized bed was also undertaken by measuring the tensile strength of fibers recovered at two temperatures. It is concluded that low bed temperatures and short bed residence times are required to maximize the strength of the recovered fibers.
A new phosphite offers an excellent balance of properties
Authors: Avakian Roger , Gardner Pamela 
Published: April 2004

AbstractPhosphites are a critical component of stabilizer formulations and provide molecular weight and color protection to the polymer. This paper profiles a new phosphite antioxidant whose structure provides an excellent balance of high activity, hydrocarbon solubility, and excellent handling characteristics. A wide range of performance data is illustrated in polypropylene.
Mechanical properties and impact toughness of talc‐filled β‐crystalline phase polypropylene composites
Authors: Tjong S. C. , Li R. K. Y. 
Published: April 2004

AbstractInjection molded β‐crystalline phase polypropylene (PP) composites containing 5, 10, 20, 30 and 40% (by weight) of talc filler were studied by X‐ray diffraction, scanning electron microscopy, static tensile and falling drop weight impact tests. The X‐ray diffraction analysis showed that the talc filler suppresses the formation of β‐form PP dramatically. As a result, the β‐PP composites containing talc content ≥20 wt% consisted mainly of the α‐form PP phase. The tensile test showed that the addition of talc filler up to 40 wt% leads to an increase in Young's modulus whereas little effect is observed on the yield strength of composites with the addition of talc up to 30%. This behavior can be attributed to the load bearing effect of talc particles with a platelike structure and to good interfacial bonding exists between the matrix and filler. The impact tests revealed that the critical stain energy release rate (Gc) of the β‐PP polymers appears to increase initially with the addition of 5 wt% talc; thereafter it decreases significantly with increasing talc content.
Study of additive compatibility with poly (vinyl chloride). 1: Dynamic mechanical analysis (DMA) of impact modified rigid PVC containing ester lubricants
Authors: Bacaloglu Radu , Hegranes Barbara , Fisch Michael 
Published: April 2004

AbstractThe glass transition temperatures of impact modified PVC with different amounts of lubricants have been used to define two new parameters of lubrication: the saturation concentration and the efficiency constant. The use of lubricants at significantly lower concentration than the saturation concentration ensures their permanence in the polymer. They then act as internal lubricants reducing the viscosity of the melt. The use of lubricants at much higher concentrations ensures their release at the surface of the polymer, giving them an external character. The efficiency constant characterizes the capability of the lubricant to modify the properties of the polymer and increase flow. Polyacrylate impact modifiers form distinct polymer phases and consequently the effect of lubricants on impact modifier may be characterized in the same way by the two constants. The choice of impact modifier and lubricant for a given application can be rationally made by using the two characteristic parameters. The described procedure can be applied to any polymer and all the additives that can migrate in the polymeric phase as long as their glass transition temperatures can be measured.
A review of vinyl technology
Authors: Summers James W. 
Published: April 2004

AbstractThis is a review of PVC technology from chlorine and ethyle, to PVC polymerization, to melt processing, to properties, to recycling and environmental concerns. It is written in terms for understanding by even non‐scientists in the industry.PVC has a large sales volume, second only to polyethylene. Its high chlorine content provides it with a very high level of combustion resistance for building products, electrical enclosures, and wire & cable insulation. PVC has a unique ability to be compounded with a wide variety of additives, making it possible to produce materials in a range from flexible elastomers to rigid compounds, materials that are weatherable such as for siding and windows, compounds that have stiff melts and little elastic recovery for outstanding dimensional control useful in profile extrusion, or low viscosity melts, which compete effectively with ABS and PC/ABS in thin walled injection molding parts such as computer monitor housings.Some of PVC's properties are attributed to unique structures. The polymer precipitates from its monomer and grows into primary particles, which are later the melt flow units. Fusion into larger structures and product strength are controlled by break‐down of the grains into primary particles, by the choice of additives, by the amount of melting (temperature), and by the number of tie molecules (molecular weight).The main type of polymerization is the suspension process, with significant polymerization made by the mass process and emulsion process. In the suspension process, the polymerization takes place in droplets of monomer suspended in a water.PVC is environmentally sound. With over 50% chlorine content, chlorine makes PVC one of the most energy efficient polymers, makes PVC inherently flame retardant, and acts as a marker, enabling automated equipment to sort PVC containers from other plastics in the waste stream. Analysis from 155 large‐scale, commercial incinerator facilities found no relationship between the chlorine content of waste nor the addition of PVC, and dioxin emissions from combustion processes. New requirements from the U.S. EPA make scrubbers mandatory on all incinerators and are necessary whether or not PVC is present in the waste feed.
Pimelic acid‐based nucleating agents for hexagonal crystalline polypropylene
Authors: Li J. X. , Cheung W. L. 
Published: April 2004

AbstractIsotactic polypropylene (PP) resin was doped with pimelic acid, sodium pimelate, and calcium pimelate to stimulate the growth of hexagonal crystalline polypropylene (β‐PP). The doped resin was crystallized in a differential scanning calorimeter (DSC) and during compression molding and injection molding. The effect of the additives on the formation of β‐PP was examined using DSC and wide angle X‐ray scattering (WAXS). Pimelic acid alone was found ineffective while the pimelates induced 64% to 90% of β‐growth depending on the nucleating agent system and crystallization condition. In particular, the pimelic acid/calcium stearate system produced a more consistent and higher yield of β‐PP. This was attributed to finer particle size and better dispersion of the nucleating agent.