bluuebunny/crossref_metadata_2025_split huggingface dataset:
Orientation and Position Dependant Thermal Conductivity
Authors: Mathis Nancy , Chandler Christina 
Published: July 2017

Thermal conductivity is a critical thermophysical property to be monitored while manufacturing foam insulation for industries from construction to appliances. Formulators rely on lab based testing to measure thermal conductivity of new materials that are under development to assure that the product meets the needs of the customer. Quality control engineers rely on lab based testing to periodically measure thermal conductivity of the product to assure that the goals of the formulators are being realized on a consistent basis. Lab based testing has been dominated by traditional guarded hot plate techniques which require access to both sides of a flat, prepared sample of fixed dimension. The entire volume of the sample is measured during testing, providing the average thermal conductivity of the sample as the result. This study has measured the variation in thermal conductivity across the profile of polyurethane. Further investigation focused on detecting thermal conductivity anisotropy in foam as related to foam rise direction. This research was facilitated by the use of a new technique that has been developed for thermal conductivity testing which requires access to only one side of the sample. With this interfacial transient technique, testing time dictates the penetration depth of the heat wave, and therefore the amount of material tested. This technique does not require set sample configurations, which eliminates the need to mock up samples for evaluation.
Polymeric Foam by Photoinitiated Polymerization of Trimethylolpropanetriacrylate: Initiator and Solvent Effects
Authors: Apen Paul G. 
Published: July 2017

A comprehensive examination of the preparation of polymeric foam via the photopolymerization of trimethylolpropanetriacrylate, TMPTA, was undertaken. Foam properties such as uniformity, shrinkage, density, microstructure, physical integrity, and machinability were measured as a function of initiator, solvent, and processing conditions. The photopolymerization rate of TMPTA in poly(oxyethylene[4]) lauryl ether, or Brij 30, and glycol ethers is enhanced using active photoinitiators such as benzoinethylether and 2,2-dimethoxy-2-phenylacetophenone. The properties of the TMPTA foams were identical for all photoinitiators examined. The properties of the TMPTA foams were dramatically changed when a co-solvent was employed. The co-solvents were triethyleneglycol dimethyl ether and triethyleneglycol monomethyl ether. The use of co-solvents leads to greater shrinkage and a higher than expected foam density. Unlike foams prepared in Brij 30, foams prepared using glycol ethers possess good physical properties and can be machined into cylinders with a smooth surface finish.
L-2100, a New Silicone Surfactant for Use in High Resilience Slabstock Foam
Authors: Grabowski W. , Desnier M. C. 
Published: July 2017

A new high resilience (HR) slabstock foam stabilizer, Union Carbide Silicone Surfactant L-2100 (formerly Y-10704), has been discovered through the systematic study of surface tension and foam effects as the structure of this general class of siloxanes was varied. The investigations described in this paper show the influence of polarity of the pendant group grafted on the siloxane as a way to modify the properties of the silicone. The precise structure associated with L-2100 was defined through extensive evaluations in a variety of foam formulations including those containing SAN polymer polyols and melamine. The reduction of the surface tension of a complex polyurethane reaction mixture is a prerequisite to creating foam. Determining the proper siloxane structural parameters to satisfy these demanding requirements can be arrived at by carefully balancing the siloxane size with the character of the moiety attached to the silicon atom. The measurements of surface tension reduction in polyol solutions containing different foam stabilizer, coupled with thermodynamic calculations, have given us a better understanding of the role of high resilience foam. These fundamental findings led to the development of the Silicone Surfactant L-2100 already commercially available. The innovative molecular parameters designed into this novel, new HR surfactant provide for optimum surface activity to produce a stable, yet open foam, with outstanding processing characteristics. This new HR silicone surfactant has been successfully scaled-up, and its performance has exhaustively been evaluated in a variety of formulations on pilot scale equipment and in industrial foam facilities. Foams produced with L-2100 give excellent fingernailing and a regular nondeformed shape on the line. Additionally, increasing the concentration of L-2100 does not result in tighter foam. The performance and processing characteristics are a clear step forward in stabilizer technology and have been achieved through an alignment of the molecular parameters on the silicone backbone.
Novel Methods of Modification in Isocyanurate Foams
Authors: Gou J. , Sasaki K. , Ashida K. 
Published: July 2017

This paper describes novel methods of producing modified isocyanurate foams having low combustibility, high thermal stability and low smoke density. The research philosophy in this study is based on a hypothesis that by increasing the thermal stability of polymeric linkages, less flammable gases are generated which result in foams having lower combustibility, higher flame resistance, and higher thermal stability. The thermally-stable linkages employed in this study are amide-, imide-, and imide/carbodiimide linkages. Amide-modified isocyanurate foams were prepared by either a one step process or a two step process, using dimer acid, adipic acid or di-ketimine as modifier. The foams prepared by the two step process using adipic acid exhibited high closed cell content and therefore higher thermal insulation and high temperature stability. Imide-modified isocyanurate foams exhibited high flame-resistance and high closed cell content.
Flammability Characteristics of CO2 Blown Rigid Polyurethane Spray Foam
Authors: Moore S. E. , Bhattacharjee D. , Dressel D. 
Published: July 2017

In view of the ozone depletion potential of HCFC-141b and other HCFCs, processing challenges with gaseous HFC-134a, and flammability potential with pentanes as blowing agents, significant efforts have been deployed in the development of environmentally friendly, all carbon dioxide blown rigid polyurethane spray foams. These foams are primarily used for the insulation of roofs, storage tanks, vessels, walls and piping. The Mannich base initiated Polyol A, developed by The Dow Chemical Company [1], with viscosity of ∼2000 cps at 77°F and OH# of ∼312 was manufactured using patented technology. This OH# is significantly lower than that of the dominating spray foam polyols (OH# 470). The low viscosity and higher equivalent weight of this polyol are designed to alleviate the processing difficulties of typical carbon dioxide blown spray applied systems. Some of the important requirements in spray systems are the flammability characteristics. Most carbon dioxide blown foams, however, suffer from high heat release, smoke and weight loss in small scale burn tests like the Ohio State University (OSU; ASTM E-906) test when compared to the corresponding results with HCFC-141b as the primary blowing agent. A series of formulations containing Polyol A, aromatic polyester polyols and commercially available fire retardants were evaluated at different isocyanate indices. Flammability properties were determined using a variety of small scale test methods including cone calorimeter and ASTM E-906. In an attempt to understand factors contributing to burn properties, several analytical techniques, such as FTIR (Fourier Transform Infrared Spectrometry), TGA (Thermo-Gravimetric Analysis) and DMS (Dynamic Mechanical Spectroscopy) were utilized. Analysis of the FTIR spectra leads to an estimate of conversion of isocyanate end groups and trimerization reactions where applicable. TGA reflects the chemical stability of the polymer network to thermal decomposition and DMS reflects the physical stability of the polymer network. A correlation of these data with the weight loss data after burning has been investigated. A combination of these techniques leads to a systematic approach for the development of spray polyurethane foams with improved flammability characteristics.
Reduced Density Carbon Dioxide Blown Foam Based on a Novel Polyol Technology
Authors: Nichols J. B. , Bhattacharjee D. , Moreno O. , Mirasol S. , Tabor R. 
Published: July 2017

In view of increasing pressure to use environmentally acceptable, nonflammable blowing agents with zero ozone depletion potential in the manufacture of rigid polyurethane foams, there is greater interest in 100% carbon dioxide blown technology. When trichlorofluoromethane (CFC-11) or 1,1-dichloro-1-fluoroethane (HCFC-141b) is replaced by carbon dioxide as the cell gas, the resulting foam, in general, suffers from higher thermal conductivity (k-factor), poorer adhesion and worse flowability leading to higher density. The water level in the formulation can be increased to improve flowability of these systems, but foam with poorer dimensional stability is obtained due to rapid diffusion of carbon dioxide out of the foam. In order to maintain adequate dimensional stability, similar to what is achieved in CFC-11/HCFC-141b blown systems, the water level has to be reduced. This leads to unacceptably higher foam density. In addition, the higher k-factor of the foam is primarily due to higher gas k-factor of carbon dioxide compared to those of CFC-11 and HCFC-141b. This is partially offset by lower radiative contribution arising from finer cell structure of carbon dioxide blown foams. Certain applications, however, are less sensitive to the energy requirement, and a foam with higher k-factor may be acceptable. This paper deals with a design of experiments to yield a foam with good processability and excellent dimensional stability in a variety of conditions, while maintaining the in-place density usually obtained with CFC-11/HCFC-141b blown systems. The key to the success was the development of a novel polyol that led to dimensionally stable foams at higher levels of water. The commercial viability of this technology has been demonstrated by producing actual parts without any equipment modifications.
Techniques to Assess the Various Factors Affecting the Long Term Dimensional Stability of Rigid Polyurethane Foam
Authors: Singh S. N. , Lynch J. J. , Daems D. 
Published: July 2017

CFC blowing agents have been eliminated from virtually all polyurethane foam applications and replaced, in many cases, with the more environmentally acceptable HCFCs, or in some cases in Europe, with hydrocarbons. At the same time, the search continues for zero ozone depletion potential blowing agents and some possible candidates are HFCs, hydrocarbons and water. The physical properties such as boiling point and solubility characteristics of the new blowing agents vary widely and formulations have had to be adapted to new types of blowing agents in order to achieve acceptable processing and resultant foam properties. One of the big limitations to adapting formulations has been the ability of the present test methods to predict performance of foam blown with the new blowing agents. Predictive tests for the dimensional stability of fully CFC-11 blown systems have proven their validity over the years. But such is not the case with foams blown with the new blowing agents. ICI developed a new, more stringent, test to predict the long term dimensional stability performance, and the results of some preliminary evaluations were presented at the last SPI meeting in Boston. This new test focuses on accelerating the normal diffusion processes that typically take place over a period of months or years. This latest paper is directed towards gaining an additional understanding of the matrix plasticization effects of various types of blowing agents and describes a method for quantifying such an effect. It also shows how these new evaluation techniques serve as useful development tools for foam based on third generation blowing agents. Both construction and appliance systems based on PIR and PUR technology are elucidated. Some results from the long term aging of boards and refrigerator/freezer cabinets and comparison of these results with the prediction of the new dimensional stability test method are also discussed. The results discussed here show that industry may be guided in selecting appropriate alternative blowing agents and in the development of current/future formulations and processing by more accurately comparing the long-term dimensional properties using the reliable and accurate test procedures developed in this fundamental study.
Skin Development in Free Rise, Flexible Polyurethane Foam
Authors: Yasunaga K. , Zhang X. D. , Macosko C. W. 
Published: July 2017

The behavior of top skin layer in reacting flexible polyurethane foam was studied to interpret its role in determining the properties of the foam. Temperature profile near the top skin rises much slower than that at the center of the foam bun. Parallel plate rheometer and infrared spectroscopy showed that the material near the top skin is still liquid after the onset of cell opening at the center of the bun, due to the slow temperature increase. The cells near the top skin are supposed to still be closed at visual blow-off. The visual blow-off time changed with different silicone surfactant structure used in the formulations, although the onset of cell opening time did not change. This indicates that surfactants are playing some role to prevent CO2 gas from coming out by breaking the top skin and cell layers under it. Cell opening was shown to be continuously occurring between onset of cell opening and visual blow-off time. Delaying the visual blow-off was efficient to get higher foam bun height and could affect air flow rate. However, the visual blow-off time alone cannot account for the difference in the air flow of final foam products.
Comparative Evaluations of Alternative Blowing Agent Systems in Appliance Foams and Cabinets
Authors: Brown L. J. , Morgan R. E. , Haworth G. J. , Beerwart A. 
Published: July 2017

The Manufacture of HCFC-141b (used as an insulation foam blowing agent) will be discontinued in the United States on December 31, 2002. In addition, the United States appliance industry must meet a U.S. Department of Energy (DOE) requirement for energy redaction of up to 30% (compared to 1993 standards) by July of 2001. Feasibility testing of alternate blowing agent foams was previously reported by the AHAM Industry/Government CFC Replacement Consortium and indicated a 6-10% increase in energy with cylopentane blown foams. The evaluations of HFC-245fa and HFC-236ea blown foams in non-optimized systems also had higher k-factors than HCFC-141b blown foams. The Dow Chemical Company and Maytag-Galesburg Refrigerator Products have conducted additional blowing agent evaluations on a newly designed top freezer cabinet. HFC-245fa, HFC-236ea and cyclopentane have been evaluated and compared to HCFC-141b in rigid appliance systems utilized today. Several new polyols, surfactants and catalysts were utilized in this formulation design experiment. The performance of each of the alternative blowing agents was evaluated in laboratory samples and in refrigerator/freezer cabinet foaming trials.
Structural Apperception in the Absence of Syntactic Constraints
Authors: Tikofsky Ronald S. , Reiff Donald G. 
Published: July 2017

Twenty-eight subjects were presented with computer generated grammatically deviant strings and asked to carry out two tasks on each of two experimental days. Task 1 was a forced-choice experiment in which 50 pairs of strings were presented aurally to each subject, and he had to select that member of the pair which he felt was the best approximation to a good English sentence. In Task 2, subjects were required to read and rank each string on a scale running from 1 (completely unacceptable) to 5 (completely acceptable). A different order of stimulus presentation was employed on each experimental day; 14 subjects were assigned to one order on the first day and received the other order on the second day. Results show that subjects tend to prefer the same statement over orders and that rank and preference are highly correlated. There are considerable differences in preference among the 50 pairs of stimulus items. Analysis of the data suggests that this task yields information relevant to the linguistic and in particular the syntactic competence of subjects when applied to grammatically deviant strings. Subjects appear to be trying to cope with the statements by comparing them to acceptable syntactic and/or semantic patterns.
A Study of Cohesive Patterns and Dynamic Choices Utilized by Two Schizophrenic Patients in Dialog, Pre- and Post-Medication
Authors: Abu-Akel Ahmad 
Published: July 2017

The present study evaluated the communicative deficits in the linguistic performance of two Arabic speaking schizophrenics having a first episode of disorganized schizophrenia. Two facets of the conversational performance of each patient prior to and following antipsychotic medication treatment were considered and compared to normals' performance of these two measures. These were the dynamic development of the interviews and selected cohesive devices. A description of the patients' aberrant conversational behavior and deficits in terms of systemic grammar is offered for profiling schizophrenics' discourse and measuring the effects of stimulant treatment. The neuroleptic clozapine led to both positive and negative changes in the socially appropriate use of language in the schizophrenics' conversations.
Studies in Cross-Linking Reactions of Cellulose
Authors: Chipalkatti V. B. , Desai R. M. , Sattur N. B. , Varghese J. , Patel J. G. 
Published: July 2017

With a view to studying the effect of bulky substituents in the cross-linking molecule on the physico-chemical properties of reacted cellulose, 1:3-dichloro-2-propanol and its acetyl, propionyl, and butyryl esters have been reacted with cellulose. Two cotton fabrics have been used: (i) a casement cloth of open structure and (ii) a poplin fabric of closed construction. The presence of cross-links and the retention of the ester groups in the cross-links have been established by the determination of the insolubility of the treated cellulose in cuprammonium hydroxide and the estimation of the ester contents. The effect of the substituent ester groups on the reactivity of these compounds and the resulting changes in the physico-chemical properties of the treated fabrics, such as dry and wet crease recovery, tensile strength, tear strength, stiffness as bending length, moisture regain, etc., have been assessed. It has been found that the cross-linking reactivity of these compounds decreases with the increase in molecular weight. Besides this, the ester group exerts a distinct influence on the various properties mentioned above. It is observed that the improved wet crease recovery, increased moisture regain, and stiffness of the fabrics treated with these compounds are inversely related to the increasing molecular weight of the substituent ester group. Similarly the losses in tensile and tear strength and the decrease in dry crease recovery become less as the molecular weight of the substituent ester group increases. Further work with heavier substituent groups is in progress.
Processing of Ternary Polymer Blends Based on Poly(Vinyl Chloride), Thermoplastic Polyurethane and Polyethylene-Co-Acrylate-Co-Co. Part I: Dynamic Mechanical and Morphological Properties
Authors: Modesti M. , Tiberio M. I. , Simioni F. , Passudetti M. , Zinelli G. , Veronelli M. 
Published: July 2017

Blending PVC with other polymers has proven to be a viable approach in developing higher performance flexible PVC-based materials with a potential for more extensive applications, traditionally dominated by rubbers and thermoplastic elastomers. Miscibility in polyvinyl chloride (PVC)/thermo-plastic polyester polyurethane (TPU)/poly(ethylene-co-normal butyl acrylate-co-carbon monoxide) (ENBACO) ternary polymer blends, was assessed by means of dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM) analysis techniques. Experimental design was performed by using a software program called "ECHIP" that makes it possible to perform statistically designed experiments with a minimum number of trials. The results confirmed total miscibility in the composition range examined: 30% <%PVC < 60%, 0% <%TPU < 40% %ENBACO = 100 - (%PVC +%TPU) Because of the differences in the physical properties of polymer materials used to blend with PVC, research on the most suitable process parameters to achieve miscible blends without degrading them revealed a rather narrow processing window.
Hearing Preservation in Acoustic Neuroma Surgery: Value of Monitoring Cochlear Nerve Action Potentials
Authors: Nedzelski Julian M. , Chiong Charlotte M. , Cashman Marlene Z. , Stanton Susan G. , Rowed David W. 
Published: July 2017

This study reviews the hearing results in 80 consecutive patients who underwent complete removal of histologically proven acoustic neuromas by use of the suboccipital approach. Of these, 56 patients had successful monitoring of cochlear compound action potentials; 20 were not monitored because their surgery predated monitoring; and 4 had unsuccessful monitoring. A significant difference was found in hearing preservation rates between the group in whom compound action potential monitoring was performed and those in whom monitoring was either unavailable or failed (p = 0.02). Overall, 38% (30 of 80) had preserved hearing. There were 51 patients in whom the click threshold for the cochlear compound action potential was measured during surgery. Twenty‐one patients had a threshold shift of 20 dB or less, 15 (71%) of these retained serviceable hearing (speech reception threshold ≤50 dB; speech discrimination score ≥60%). Of 12 patients in whom the threshold shift was 30 to 60 dB, none had serviceable hearing after surgery. The click threshold shift was predictive of a significant postoperative hearing change (p < 0.001).
The apparent diffusion coefficient is strongly correlated with extracellular volume, a measure of myocardial fibrosis, and subclinical cardiomyopathy in patients with systemic lupus erythematosus
Authors: Wu Rui , An Dong-Aolei , Hu Jiani , Jiang Meng , Guo Qiang , Xu Jian-Rong , Wu Lian-Ming 
Published: July 2017

Background Extracellular volume (ECV) has been histologically validated as a non-invasive quantitative index of myocardial fibrosis that does not require the use of contrast, which is contraindicated in patients with renal insufficiency. Purpose To evaluate the correlation between the contrast-free apparent diffusion coefficient (ADC) and ECV, an index of fibrosis. Material and Methods Twenty-four patients with systemic lupus erythematosus (SLE), who were predominantly women (mean age = 36 ± 12 years) and 12 normal participants (mean age = 38 ± 10 years) underwent cardiac magnetic resonance (CMR) via 3.0 T MR with T1 mapping. Diffusion-weighted imaging (DWI) and late gadolinium-enhanced (LGE) imaging served as the reference standards with which CMR was compared. The mean ADC, native T1, and ECV were calculated for each patient, and the correlations among these parameters were analyzed. Results Both SLE LGE-positive (LGE+) and SLE LGE-negative (LGE–) participants had higher native T1 values, ECV, and ADC than normal controls ( P < 0.05). SLE LGE+ participants exhibited a higher ECV (0.31 ± 0.02) and ADC (2.44 ± 0.32 × 10−3 mm2/s) than SLE LGE– participants ( p < 0.05); however, SLE LGE+ and SLE LGE– participants had similar native T1 values (1227 ± 48.81 ms versus 1174.70 ± 95.80 ms, respectively; P > 0.05). ADC values were positively correlated with increased ECV (R2 = 0.62) and native T1 values (R2 = 0.28) in all participants. Conclusion ADC measurements are a suitable alternative to ECV that may be used to assess and quantify myocardial fibrosis in patients with SLE.