摘要:

AbstractA new technology for the production of highly concentrated aqueous formaldehyde was developed by oxidizing methylal. Whereas the oxidation of methanol yields 1 mol of water per 1 mol of formaldehyde, methylal oxidation produces only 1 mol of water for every 3 mol of formaldehyde. Thus, the output from methylal oxidation is more than 70% formaldehyde compared with 55% from methanol oxidation. For this purpose, basic research for methylal synthesis was tried and the world's first commercial production of methylal was accomplished. Using this methylal, the world's first technology of methylal oxidation for manufacturing highly concentrated aqueous formaldehyde was established by development of a new methylal oxidation catalyst composed of iron, molybdenum, and a third component. This highly concentrated aqueous formaldehyde is then fed to the acetal homopolymer and copolymer plant whose combined capacity is 35,000 tons/years. © 1993 John Wiley&Sons, Inc

ISSN:0021-8995    

DOI:10.1002/app.1993.070500801

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractTo develop a new technology for the purification of formaldehyde from formalin by a distillation method, the vapor‐liquid equilibrium of formaldehyde—water binary systems was investigated. Based on the studies of Thompson et al. and Iliceto et al., the vaporliquid equilibrium of formaldehyde and water are calculated and these calculations are in good agreement with the reported data. It was found that the vapor pressure of formaldehyde is determined by the free formaldehyde concentration (mol/L), whereas the vapor pressure of water is determined by the molar ratio of free water. The vapor‐liquid equilibrium of formaldehyde‐water in the presence of a diluent was also investigated. It was shown by calculation that in some cases, when the concentration of the diluent is high, the volatility of formaldehyde is always higher than that of water and these calculations are in good agreement with experimental data. Based on this principle, the purification of formaldehyde by an extraction distillation method was established. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070500802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractConventionally, acetal homopolymer or copolymer is obtained by the polymerization of formaldehyde or trioxane, following the end‐capping using acetic anhydride or unzipping of the unstable polymer end fraction. First, Asahi Chemical developed a new process to obtain an end‐capped polymer during polymerization of highly purified formaldehyde using acetic anhydride as the chain‐transfer agent. Use of highly purified formaldehyde and endcapping during polymerization using acetic anhydride as a chain‐transfer agent or an endcapping agent will provide a simple process for manufacturing acetal homopolymer. The polymerization mechanism was confirmed by infrared spectroscopy analysis and proton NMR analysis of the polymer obtained. Second, for the acetal copolymer, purified trioxane was copolymerized with ethylene oxide in the presence of methylal, which gave an endcapped polymer with high thermal stability. Two new intermediates from the initiation reaction of the copolymerization, 1,3,5,7‐tetraoxacyclononane (TOCN) and 1,3,5,7,10‐pentaoxacyclododecane (POCD), were isolated and a new initiation mechanism was proposed. © 1993 John Wil

ISSN:0021-8995    

DOI:10.1002/app.1993.070500803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractPoly(acrylic acid) (PAA) can form stable and insoluble gels with FeCl3in water or in H2O2(30 wt %). Two carboxylic groups are complexed by the FeCl2+ion. PAA‐FeCl3(2 : 1) gels have found practical application in the blocking of microscopic channels in tooth dentin and thereby decrease the fluid permeability and protect against tooth decay. © 1993 John Wiley&Sons, I

ISSN:0021-8995    

DOI:10.1002/app.1993.070500804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAn epoxy resin, consisting of diglycidylether of bisphenol A (DGEBA) and methyltetrahydrophtalic anhydride (MTHPA), was cured against peel‐plies coated with different poly(vinylalcohol‐co‐vinylacetate) (PVOH). The epoxy polymer surface was characterized with X‐ray photo electron spectroscopy (XPS), contact angle measurements, and scanning electron microscope (SEM). PVOH, which is a water soluble polymer, was detected at the cured epoxy polymer surface with XPS after washing with hot water. The PVOH polymer at the outermost surface has hydroxyl groups, which can react with both the adhesive and the epoxy resin. The modified epoxy composite surfaces were adhesively bonded with a polyurethane and an epoxy adhesive. Improved adhesion was obtained between modified epoxy composite surfaces and different adhesives. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070500805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractDifferences in surface chemical composition were found when examining poly(vinylacetate‐co‐vinylalcohol) (PVOH) film surfaces. The content of the acetate groups increased at the outermost surface when dried in air and similar content, when dried against a glass surface, compared to the bulk content. The enrichment varied from 200–1300%, as compared to the bulk content. The enrichment of the acetate groups was studied with X‐ray photo electron spectrocopy (XPS or ESCA) at different analyzing angles. The bulk content was measured with Nuclear Magnetic Resonance spectrometry (NMR). © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070500806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractMechanical scission of two typical perfluoropolyethers was investigated: Y, a copolymer of CF(CF3)CF2O, CF2O, and CF(CF3)O, and Z, a copolymer of (CF2)nO, withn= 1,2,3,4. Undiluted polymers were subjected to prolonged shearing in a media mill with ZrO2particles. A chemical extraction of the polar ZrO2particles was carried out to collect adsorbed polar scission products. Mechanochemical scission products from both the Y and Z fluorocarbon polymers were identified by19F‐NMR. A significant amount of CF3CO2−was present after the milling and the primary functional groups formed at scissioned chain ends were CO −2. A hydrodynamic expression was derived and the maximum extension rate was estimated to be in the range of 5 × 106s−1. Initial degrees of polymerization were between 20 and 200, well below levels for which flow‐induced scission is expected to occur. Final degrees of polymerization were less than 10, and the scission was noncentral and nonrandom in both polymer

ISSN:0021-8995    

DOI:10.1002/app.1993.070500807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractBlends of poly(vinyl chloride) (PVC) and epoxidized natural rubber (ENR) were prepared by melt‐blending and studied using a Monsanto rheometer, infrared spectrophotometer, and dynamic mechanical analyzer. The PVC/ENR blends were found to be self‐crosslinkable, but immiscible at 25/75, 50/50, and 75/25 blend ratios. However, addition of a third reactive polymer, such as carboxylated nitrile rubber (XNBR), can make the ternary blend miscible. The quantity of XNBR required to make the binary blend miscible depends on the blend ratio of the binary PVC/ENR blend and increases as the binary blend ratio changes through 25:75 to 50:50 to 75:25. © 1993 John Wiley&Sons,

ISSN:0021-8995    

DOI:10.1002/app.1993.070500808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe melt viscosity of polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) blends relative to PC is significantly lower, even lower than that of pure ABS in some compositions. Annealing above theTgof PC coalesces and coarsens phase structure in core and skin regions. Increase in the molecular weight of PC in PC/ABS blends results in low‐temperature fracture toughness improvement but suffers from the disadvantage of higher melt viscosity. The selection of PC in PC/ABS blends must be a compromise between the toughness advantages of higher PC molecular weight and the disadvantage of higher melt viscosity. © 1993 John Wiley&Son

ISSN:0021-8995    

DOI:10.1002/app.1993.070500809

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe objective of this study was to investigate the effects of the incorporation of ether linkages into polylactide (PLLA) chains and the time of biodegradation on the behavior of protein adsorption. The content of poly(ethylene glycol) (PEG) in PLLA/PEG copolymers is from 4.4 to 18.3 wt %, and the length of the PEG soft segment is 1000, 2000, and 6000 daltons. The bovine serum albumin (BSA) adsorption onto the biodegradable PLLA/PEG copolymers was carried out using ultraviolet spectroscopy. The surface tension of PLLA and PLLA/PEG was measured using a contact angle. The data show that the incorporation of PEG segments makes the copolymer more polar and, therefore, leads to a reduction of protein adsorption. As the hydrolysis of polymers proceeds, both PLLA and PLLA/PEG turn out to be more polar. However, the initial compositions of degraded PLLA/PEG have a weak influence on the protein adsorption onto its hydrolyzed surface with a substantially long duration of hydrolysis. This phenomenon is attributed to the hydrophobic interaction between polar PLLA/PEG and BSA. © 1993 John Wiley&Sons, Inc

ISSN:0021-8995    

DOI:10.1002/app.1993.070500810

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY