摘要:

AbstractHolocellulose prepared from steam‐exploded aspen wood was gradually fractionated with 2.5% NH4OH, 4.5% NaOH, and 17.5% NaOH, respectively. Some residual polysaccharides were extracted from the material in this way, but their yield was only about 5%. Trimethylammonium‐2‐hydroxypropyl (TMAHP)‐derivatives, exploded aspen wood (EXAW), were prepared by the reaction with 3‐chlor‐2‐hydroxypropyl trimethylammoniumchloride (CHMAC) in alkaline medium. The quantity of water and alkali extracted TMAHP–polysaccharides (yield 2.6%) was lower than the yields from modified healthy beech and aspen, as well as rotten aspen. On the other hand, we can obtain more modified cellulose‐rich and lignin‐rich material than from previously mentioned species. The steam‐explosion process is suitable for increasing the accessibility of cellulose component in lignocellulose material for

ISSN:0021-8995    

DOI:10.1002/app.1987.070340501

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

年代:1987

数据来源: WILEY

摘要:

AbstractStructural properties of polypropylene (PP) filled with flame‐retardant (FR) organoantimony compounds, viz., triphenylstibinedibromide and triphenylantimony (V) derivatives of tribromotrichloro‐, and pentachlorophenols at 5–20 phr additive loading, were investigated through differential thermal analysis (DTA), and X‐ray diffraction (XRD) studies. Incorporation of flame retardant in PP has decreased the melting temperature (Tm) and heat of fusion (ΔHf) of PP. Crystallization peak and the onset temperature, crystallization rate and crystallite size are also influenced by the addition of these compounds. The percent crystallinity obtained by XRD is in good agreement with that obtained by DTA. The tensile properties of the flame‐retardant‐filled PP are also studied, and an attempt has been made to correlate the tensile properties with that of structural changes in polypropylene. Fracture mechanism of flame‐retardant‐filled PP has been investigated with the help of a scanning ele

ISSN:0021-8995    

DOI:10.1002/app.1987.070340502

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

年代:1987

数据来源: WILEY

摘要:

AbstractSeveral simultaneous interpenetrating networks (IPN) of castor oil polyurethane (COPUN) and polystyrene divinyl benzene (PSN) were synthesized under conditions where the free radical polymerization of styrene and the crosslinking reaction of castor oil and toluene diisocyanate progress at comparable rates. Comparison of the mechanical properties and crosslink density of the COPUN and COPUN/PSN‐IPNs indicates a marginal increase in tensile strength and crosslink density from COPUN to 60COPUN/40 PSN IPN. IPN samples prepared with further increased PSN content show steady decrease in the above properties. This reversal of the expected trend was attributed to the possible greater molecular interpenetration achieved due to similar gelation times with resultant extension of chains and increase in free volume between crosslinks. This was further confirmed from thermogravimetric data on the initial stages of decomposition of the IPN

ISSN:0021-8995    

DOI:10.1002/app.1987.070340503

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe extent to which the styrene end‐blocks of three commercially available triblock copolymers can mix with a particular poly(2,6‐dimethyl‐1,4‐phenylene oxide) (Mn= 22,600 andMw= 34,000) or PPO has been examined by investigation of the glass transition behavior of the PPO and polystyrene (PS) portions of the blends using differential scanning calorimetry. Each block copolymer has a butadiene‐based mid‐block which was hydrogenated for two of these materials, but not the third. The three copolymers differ substantially in overall molecular weight and in molecula weight of the blocks. However, in analogy with the literature on blends of homopolymer polystyrene with styrene‐based block copolymers, the molecular weight of the PS block should be the principal factor affecting the phase behavior in the present blends. Mixtures of the PPO with the block copolymers having PS blocks with M = 14,500 (nonhydrogenated midblock) and with M = 29,000 (hydrogenated mid‐block) exhibited single composition‐dependentTgs for the hard phase, indicating complete mixing of PS segments with the PPO, for all proportions. On the other hand, the block copolymer having a PS block with M = 7,500 and a hydrogenated mid‐block exhibited two separate hard phaseTgs corresponding to an essentially pure PPO phase and a PS‐rich phase. For blends of homopolymer PS with styrene‐based block copolymers, the similar two‐phase behavior of the glassy portion can be readily explained by entropic considerations. For the present case, the favorable enthalpic contribution for mixing PPO and PS is an additional factor which seems to influence the restrictions on molecular weight for complete mixing; however, additional work is needed to develop a more quantitative ass

ISSN:0021-8995    

DOI:10.1002/app.1987.070340504

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe transport of gaseous ethylene oxide (EtO) in several polymer films is studied using the carrier gas method of measurement. Permeability, solubility, and diffusion coefficients describing ethylene oxide (EtO) transport in polypropylene, polyvinylchloride, Teflon‐FEP copolymer, and polyethylene films have been obtained over a 30 Celsius degree range at a low concentration of EtO using the carrier gas method of measurement. The results indicate that the diffusion of EtO in polyethylene is independent of penetrant concentration over the range of concentrations used. However, concentration‐independent diffusion could not be verified directly for the other films studied. Two different techniques of determining diffusion coefficients were used, and within the precision of the data both yield the same result. An excess enthalpy of solution for the solubility of EtO in Teflon‐FEP copolymer was calculated, an observation that suggests that dual‐mode sorption may be takin

ISSN:0021-8995    

DOI:10.1002/app.1987.070340505

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

年代:1987

数据来源: WILEY

摘要:

AbstractThermal and optical properties of multilayer films of miscible polyethyloxazoline (PEOx) and poly(styrene‐co‐acrylonitrile) have been studied as a function of time and temperature. Differential scanning calorimetry showed that the distinct, characteristicTg's of the component polymers of the original films disappear after only short heating periods aboveTg, and a single transition appears. The new transition region is broad at first, but narrows on subsequent heating. The measurement of light transmittance as a function of wavelength through the heat‐treated films also confirms the diffusion of the miscible polymers and gives results which are comparable to the thermal measurements. Films from immiscible polymers of polystyrene and PEOx retain their properties after various heat treatments. A qualitative discussion of the diffusion process as examined by the thermal measurements is pres

ISSN:0021-8995    

DOI:10.1002/app.1987.070340506

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

年代:1987

数据来源: WILEY

摘要:

AbstractA novel series of water‐soluble polyester surfactants has been prepared by the polymerization of SIPM, PA, and PEG. The unique structural features of these surfactants have been confirmed by IR and NMR analyses. These water‐soluble polyester surfactants have been found to exhibit excellent surface active properties including surface tension, low‐foaming, solubilization, and dispersant properties for disperse

ISSN:0021-8995    

DOI:10.1002/app.1987.070340507

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

年代:1987

数据来源: WILEY

摘要:

AbstractElectron spectroscopy for chemical analysis (ESCA) and Fourier‐transform infrared (FT‐IR) attenuated total reflection (ATR) studies have been made on the film of blend polymers consisting of poly(hydroxypropyl ether) of bisphenol A (P) and poly(ethylene oxide) (E) or P and poly(ethylene adipate) (A) formed on nylon‐6 (Ny) substrate to investigate the boundary‐phase structure between the substrate and the polymer blends. For the case of P/A blend, A is enriched to the depths probed by both ESCA (below ca. 60 Å) and FT‐IR‐ATR (below ca. 0.7 μm) from the nylon‐6 surface. For the P/E blend, though P is enriched to the depth probed by ESCA from the Ny surface, the enrichment of neither of the blend components can be found to the depth probed by FT‐IR‐ATR. These results indicate the different susceptibility between P/A and P/E blends to the influence fr

ISSN:0021-8995    

DOI:10.1002/app.1987.070340508

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe concept of extinguishability as a measure of textile flammability is reviewed. Definition and determination of extinction oxygen index enables a parameter to be defined from which the effects of ignition time and fabric structure may be removed. This so‐called extinction oxygen index (EOI) and the derived value at zero ignition time [EOI]0more exactly define the burning/nonburning fabric boundary than does the more widely used limiting oxygen index (LOI). This first paper reports the determination of EOI and [EOI]0values for a series of cotton fabrics in the temperature range 20–200°C. The influence of the various fabric parameters of area density, air permeability, sample thickness, bulk density, and moisture content was investigated. The advantages of using the EOI rather than the LOI concept as a measure of textile flammability is indicated in the discussion of the results of this study with reference to previous work concerned with LOI data for cotton. In particular, the significance that environmental temperature has on EOI and related parameters reported here and previously reported LOI data is discussed in terms of various published models which define the burning/extinction thres

ISSN:0021-8995    

DOI:10.1002/app.1987.070340509

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

年代:1987

数据来源: WILEY

摘要:

AbstractInjection‐molded polystyrene surfaces were chemically modified rendering them protein reactive. The process involves chlorosulfonation of the aromatic ring, sulfonamide formation with excess di‐ and triamines, and reaction of the residual pendant amines with various bifunctional molecules. Surfaces possessing pendant bromoacetyl, iodoacetyl, fluorodinitrophenyl, and trimellitic anhydride were prepared and can exhibit up to ten times more protein immobilization capability compared to unfunctionalized polystyrene, where the coupling takes place presumably via hydrophobic interact

ISSN:0021-8995    

DOI:10.1002/app.1987.070340510

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

年代:1987

数据来源: WILEY