Type Of Polyol Research Articles

Effect of polyol type on the surface structure of sulfonate‐containing polyurethanes

Polyurethanes based upon polytetramethylene oxide (PTMO) as the polyol and derivatized with propyl sulfonate functionality pendant from the urethane nitrogen have previously been shown to possess good blood-contacting properties. Other investigators have shown that sulfonated polyurethanes containing polyethylene oxide (PEO) as the soft segment are much more thrombogenic than those containing PTMO as the soft segment. In this article, the surface properties of sulfonated polyurethanes based upon either PTMO or PEO are compared. Dynamic contact angle measurements show a significant decrease in the receding angles of the sulfonated PTMO-containing polyurethane as compared to its nonsulfonated precursor polymer. No significant difference is seen between the receding contact angles of either the sulfonated PEO-based polyurethane or its nonsulfonated analog. Variable-angle electron spectroscopy for chemical analysis (ESCA) studies of sulfonated PTMO-based polyurethane performed at room temperature show that there is a significant decrease in sulfur content at the surface. In contrast, the sulfonated PEO-based polyurethane showed little change in sulfur content with take-off angle. Finally, ESCA studies of freeze-dried surfaces show a significant increase in sulfur near the surface of the sulfonated PTMO-based polymer as compared to vacuum-dried samples but show no such increase for the sulfonated PEO-based polyurethane. It is suggested that the ability of the sulfonate functionality to be expressed at the surface may explain the observed differences in blood compatibility between the sulfonated polyurethanes based upon polyols of varying hydrophilicity.

Structure-property relationship of polyurethane ionomer

Polyurethane (PU) ionomers were prepared using various types of polyol (PTAd, PCL, PTMG, and PPG) and isocyanate (MDI, HDI, and IPDI), together with different extender (DMPA) contents, degree of neutralization, and number average molecular weight (Mn) of polyol. Modulus (E′), strength (σb), and glass transition temperature (Tg) significantly increased with the increased amount of extender and extender neutralization. Among three of the iocyanate used, PU from MDI gave the highest modulus, strength, andTg. With regard to theMn of PTAd (600, 1000, 2000), PU from PTAd 600Mn gave the highest modulus, strength, andTg, due probably to the highest hard segment content and phase mixing. On the other hand, PU from PTAd 2000Mn gave significantly improved strength over PTAd 1000Mn, and the highest elongation. The results were interpreted in terms of soft-segment crystallization, and soft-hard phase separation, which was concluded from the lowered softTg.

Extended X-ray absorption fine structure spectroscopic analysis of cation local environment in model polyurethane ionomers

The local environment of the neutralizing cation was examined by extended X-ray absorption fine structure spectroscopy in a series of model polyurethane ionomers. Polyol type, polyol molecular weight and pendant anion type had small effects on cation local environment. Sample preparation conditions had a noticeable effect in one case. The type of cation was the dominant factor in determining local ordering. The degree of local order decreased with cation type in the order Ni 2+ > Sr 2+ > Cd 2+, in agreement with the trend of decreasing tensile properties with cation type. Hydration of Ni 2+-neutralized ionomers induced no change in the Ni 2+ local environment for a sulphonated ionomer, but hydration caused a rapid change in the local structure of the analogous carboxylated ionomer. The changes were in accord with water molecules coordinating to the Ni 2+ cation.

Analysis of small-angle x-ray scattering data for model polyurethane ionomers: evaluation of hard-sphere models

The effect of pendant-anion type (sulfonate or carboxylate), polyol type (PEG, PPG, PTMG), and polyol molecular weight on the morphology of model polyurethane ionomers was studied. Analysis of the SAXS data with a liquidlike hard-sphere model revealed that the carboxylated ionomers had lower degrees of phase separation, larger aggregate sizes, and lower aggregate number densities than their sulfonated analogues. Polyol type and polyol molecular weight affected carboxylated and sulfonated ionomers similarly. Evaluation of new models of ionomer morphology for analysis of SAXS data revealed that two of the three models were inadequate

Polyurethane‐crosslinked epoxy resins. II. Compatibility and morphology

AbstractThe polyurethane(PU)‐crosslinked diglycidyl ether of bisphenol A (DGEBA) was prepared from the reaction of the pendent secondary hydroxy group in DGEBA with the isocyanate‐terminated group present in the PU prepolymer. Though the PU acted as a crosslinking agent for the DGEBA, the morphology and dynamic mechanical behaviour of these PU‐crosslinked DGEBA could be different among themselves depending on the type and molecular weight of polyols employed in the PU. There was no significant shift in the loss modulus (E″) peaks of the DGEBA crosslinked with the polyester‐type and polyether‐type polyurethanes, but the intensity of the E″ peaks increased as the polyester‐type PU employed. The morphology of this polyester‐type PU‐crosslinked DGEBA exhibited a homogeneous one‐phase system, while the DGEBA crosslinked with the polyether‐type PU showed a two‐phase morphology with the PU particles dispersed in DGEBA matrix.

Effect of the type of polyol on the soft segment crystallinity in polyurethane based on methylene bis(cyclohexyl diisocyanate)

To reveal the influence of the nature of polyols on the soft segment morphology, polyurethanes based on three polyols (polypropylene glycol 2000, polyethylene glycol 2000 and polytetramethylene glycol 2000), Methylene bis( p-cyclohexyl diisocyanate) and 1,4-butanediol were synthesized. These materials were characterized using wide angle X-ray diffraction and differential scanning calorimetry. Polytetramethylene glycol based polyurethane showed soft segment crystallinity while the other two were amorphous. This feature has been connected with the specific nature of the polyols.

Syntheses and properties of UV‐autocurable BTDA‐based polyester multiacrylates. II. Effect of polyol type and reactive monomer

AbstractSeveral families of UV‐autocurable benzophenone tetracarboxylic dianhydride (BTDA)‐based polyester multiacrylate oligomers containing pendant glycidyl methacrylate (GMA) were synthesized and the effects of acrylic functionality and polyol type on their properties were investigated. The obtained autocurable oligomers possess good pot life and are cured rapidly when exposed to ultraviolet (UV) radiation without the addition of photoinitiator or photosensitizer. Different polyols were used to obtain wide range properties of cured multiacrylate oligomers with a glass transition temperature (Tg) range of 84–130°C. A further modification of the multiacrylate oligomers was obtained by mixing them with reactive monomers having different molecular structure and methacrylic functionality.

Structure—property relationships of polyurethane ionomers with star chain architecture

AbstractThe effects of chain architecture, polyol chemistry and polyol molecular weight on the properties of elastomeric polyurethane ionomers were investigated. The type of polyol and its molecular weight had a strong influence on the rubbery modulus and tensile properties. Variations in chain architecture showed little impact on mechanical and thermal properties. Linear ionomers, threearm ionomers, and six‐arm ionomers had similar mechanical and thermal behavior.

Preparation and properties of UV‐autocurable BTDA‐based polyurethane methacrylates

AbstractSyntheses of several UV‐autocurable methacrylourethanes and the effects of polyol type on their properties are investigated. Autocurable benzophenone tetracarboxylic dianhydride (BTDA)‐based polyurethane methacrylates are prepared by addition reaction from benzophenone tetracarboxylic dianhydride (BTDA), 2,4‐toluene diisocyanate (TDI), 2‐hydroxyethyl methacrylate (HEMA), and polyol (polyethylene glycol, polydiethylene succinate, polydiethylene maleate, or polydiethylene hexamethylene‐dicarbamate). Autocurable oligomers possess good pot life and are cured rapidly when exposed to ultraviolet (UV) radiation without the addition of photoinitiator. The different polyols are used to obtain wide range properties of cured films with a glass transition temperature (Tg) range of ‐10.5‐5.5°C. Increasing the Tg of polyol shifts the dynamic mechanical storage modulus and loss factor of the cured film to high temperature. For practical application, oligomer is mixed with reactive monomers to bring the systems to a workable viscosity at room temperature. Among the monomers, the higher the composition of hydroxyethyl acrylate in the oligomer‐monomer system, the higher the curing rate of the system as compared with neat oligomer. Moreover, increasing the chain length of dimethacrylate monomers results in a decrease in breaking strength from 160 to 140 kg/cm2, in Young's modulus from 771 to 400 kg/cm2, and in glass transition temperature from 18 to 6.5°C, while the elongation at breaking increases from 70 to 130%.

A new family of ester lubricants for PVC

AbstractA new class of complex esters offers the capability for tailoring lubrication characteristics to specific PVC applications. The lubricating performance of these esters can be varied from internal to external through changes in carboxylic chain length, polyol moiety, and degree of esterification. Changes in the degree of functionality of the polyol portion of the ester can be used to affect large variations in fusion time and mill stick time. Polyol functionality may also be used to control extrudate gloss without changes in other processing parameters. Dynamic stability is relatively independent of polyol type, with all of the esters providing excellent stability behavior. Carboxylic acid chain length has a pronounced effect on external lubricity, as demonstrated by large changes in mill stick time. Esters based on stearic or longer chain acids provide optimum extrusion processability and yield high gloss extrudates at low extrusion torques. Dynamic thermal stability also increases with acid chain length. The effect of degree of esterifications on lubrication is dependent upon the polyol portion of the ester. In low hydroxyl value esters, the degree of esterification can be used to vary external lubricity.

The Use of 2,6-Toluenediisocyanate in Polyurethane Cast Elastomers

A study of the use of 2,6-toluenediisocyanate (2,6-TDI) in polyurethanes was made by comparing polymers made with pure 2,6 TDI to an 80/20 isomeric blend of 2,4/2,6- TDI and to pure 2,4-TDI. Prepolymers were prepared using three different types of polyols [polybutylene adipate, polycaprolactone, and poly(oxytetramethylene) glycol] which were end-capped with the three TDI systems. These prepolymers were cured using three types of aromatic primary diamines (MBOCA, Polacure, and Cyanacure) and a hydroxyl system composed of a 4:1 blend (based on equivalents) of 1,4-butanediol with trimethylolpropane.

Studies on the Application of Liquid Aromatic Secondary Amines as Chain Extenders and Reactive Carriers for Other Amine or Hydroxyl-Containing Polyurethane Curatives

Aromatic amines generally react rapidly with aromatic isocyanates. This reaction can be slowed to a controllable rate through the use of secondary amines. This paper demonstrates the versatility of secondary diamines as curatives for toluene diisocyanate (TDI) and diphenyl methane diisocyanate (MDI) based prepolymers. Types of polyols included in the study are polyesters such as polyethylene adipate (PEA) and polycaprolactone (PCP) and polyethers such as poly(oxytetramethylene) glycol (PTMG) and poly(oxypropylene) glycol (PPG).

The Performance of Flame Retardants in Rigid Polyurethane Foam Formulations

The flame retardant properties of rigid polyurethane foam compositions are determined by the type and level of flame retardant, the isocyanate index of the foam and the structure of the polyol. Three phosphorus-based flame retardant additives are compared using the BS 4735 horizontal burn test and the DIN 4102–B2 vertical burn test in a wide range of polyol types. The results obtained are consistent with the phosphorus content of the additives. Dimethyl methylphosphonate with a phosphorus content of 25% proves to be the most effective flame retardant. Surprisingly, the chlorine content, which accounts for nearly a third of the trismonochloropropyl phosphate molecule, does not appear to exhibit any flame retardant effect above its phosporus content. Reoflam 306, a proprietary halogen-free additive with a phosphorus content of 15·2%, enables polyurethane foams of normal index to be formulated to meet the requirements of DIN 4102–B2 without the addition of a flame retardant polyol Both test methods clearly showed that the aromatic-based polyols have inherently better flame retardant properties than the aliphatic-based polyether polyols.

PROPERTIES OF UV-CURED POLYURETHANE ACRYLATES: EFFECT OF POLYOL TYPE AND MOLECULAR WEIGHT

Several families of UV-cured polyurethane acrylates were synthesized and the effects of polyol type and molecular weight on their physical properties were investigated. Increasing polyol molecular weight led to a lower polyol glass transition temperature, a smaller amount of a separate urethane acrylate phase, and a larger chain length between crosslinks. The first two effects were reflected in lower modulus and strength at room temperature while the larger chain length between crosslinks led to higher elongation at break (room temperature) and lower modulus at high temperatures. The use of different polyols (polycarbonate, polytetramethylene oxide, polypropylene oxide, and polycaprolactone) primarily affected the room temperature modulus due to differences in the position and breadth of the polyol glass transition. The properties of materials based on isocyanatoethyl methacrylate (IEM) and toluene diisocyanate-2-hydroxyethyl melhacrylate (TDI-HEMA) were also compared.

Studies on polyurethane protective surface material resistance to cavitation erosion

AbstractThe polyurethane protective surface material, which were made from four different types of polyester and polyether polyol, have been studied with respect to their ultimate properties. The PTMG (polyoxytetramethylene glycol)‐ and PPG (polyoxypropylene giyco)‐based polyurethane protective surface materials exhibited the best results. Use of JIPNs (joint interpenetrating polymer networks), prepared from combinations of polyurethnes with an epoxy adduct with coupling agents and talc, could clearly improve the adhesive strength resistance to water in negative pressure cavitation erosion (by determination with a rotating dish apparatus) and the adhesive strength resistance toward boiling water. The polyurethane protective surface material, which was composed of three separated layers, showed better resistance to cavitation erosion than an epoxy system, poly(methyl methacrylate), aluminum, steel, and different alloys in tests using the venturi tube and the rotating dish apparatus for simulated cavitation erosion, as well as in some power stations in actual field trials.

Rigid Polyurethane Foams Extended with Partially Delactosed Whey Powder

Partially dalactosed whey powder was incorporated as an extender in rigid polyurethane foam formulations. Amounts of delactosed whey powder from 0 to 60.0% partially replaced six types of polyether polyols (OH No. 410 to 768). Polymethylene polyphenylisocyanate was the polyisocyanate and water was the blowing agent. Physical properties of the resultant products indicated acceptable textured, usable foams with good density control and dimensional stability for all whey powder additions. Increasing delactosed powder decreased compressive strength and increased open cells. Cost and property requirements would determine the amount of delactosed powder to add to foam systems.