摘要:

AbstractPeriodate‐oxidized celluloses (S‐100, S‐70, S‐50) with different degrees of oxidation were prepared. It is presented in this article that oxidized moieties of partially periodate‐oxidized cellulose are determined from analyses of1H and13C nuclear magnetic resonance (NMR) spectra of those reduction products and the corresponding polytr

ISSN:0021-8995    

DOI:10.1002/app.1991.070430301

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

年代:1991

数据来源: WILEY

摘要:

AbstractGraft polymerization of acrylic acid onto poly[1‐(trimethylsilyl)‐1‐propyne] [poly(TMSP)]film was examined. The water contact angle of poly(TMSP) film decreased remarkably from 90 to 15° by plasma treatment, which gradually increased up to 40° after several days. When the film exposed to a glow discharge was heated in an aqueous solution of acrylic acid at 80°C for 24 h, graft polymerization proceeded on the film surface, which was confirmed by ATR‐IR and ESCA spectra. Graft polymerization effectively occurred above a threshold temperature (80°C). The water contact angle of the grafted film was about 30°, and did not change with time. In contrast, when a poly(TMSP) film exposed to UV irradiation was heated in an aqueous solution of acrylic acid, graft polymerization took place not only on the film surface but also ins

ISSN:0021-8995    

DOI:10.1002/app.1991.070430302

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn order to improve the mechanical properties of polypropylene film, a new processing combining extrusion and zone‐annealing has been applied. It was found that there are suitable conditions for each step in the combined processing. When the coextrusion draw ratio was low, the total draw ratio and modulus could be increased by the zone‐annealing subsequently done. The highest modulus was obtained when the film was coextruded at extrusion draw ratio 4 and then zone‐annealed at 120°C under 7 kg/mm2. The value was 12 GPa in Young's modulus or 17 GPa in dynamic modulus. The peak temperature of αcdynamic dispersion for the combinedly processed film was 109°C, which is higher by 10°C than that for the as‐coextruded film. Four drawing methods were compared in dynamic viscoelasticity. These methods are the coextrusion, zone‐drawing/zone‐annealing, two‐step coextrusion, and the combined processing by coextrusion and zone‐annealing. The highest dynamic modulus for each method was arranged in the above order. The combined processing indicated the most effective improvement in mechanical properties, because it is believed that lamellae in the original film were broken by cooperating interaction of shear stress, compression, and tension on coextrusion and then the superstructure with a high crystallinity and a high molecular orientation was forme

ISSN:0021-8995    

DOI:10.1002/app.1991.070430303

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe miscibility of poly(tetrahydrofurfuryl methacrylate) (PTHFMA) and poly(tetrahydropyranyl‐2‐methacrylate) (PTHPMA) with some chlorine‐containing polymers was studied by differential scanning calorimetry (DSC). PTHPMA was found to be miscible with poly(vinyl chloride) (PVC), polyepichlorohydrin (PECH), and a vinylidene chloride/vinyl chloride copolymer [P (VDC/VC)] and only partially miscible with an epichlorohydrin/ethylene oxide copolymer [P (ECH/EO)]. PTHFMA was shown to be miscible with PECH and P(VDC/VC), but its miscibility with P(ECH/EO) is composition‐dependent. Information about interactions between components in PTHFMA/P (VDC/VC) and PTHPMA/P(VDC/VC) blends was estimated from melting‐point depression. The interaction parametersBwere found to be −1.7 and −3.6 J/cm3for PTHFMA/P(VDC/VC) and PTHPMA/P(VDC/VC) blend systems, respectively. The miscibility behavior of PTHFMA and PTHPMA is compared to that of poly(cyclohexyl

ISSN:0021-8995    

DOI:10.1002/app.1991.070430304

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe X‐ray photographs of fresh never‐dried cotton fibers are compared with those of dried fibers. The crystallite size of never‐dried cotton fibers shows no significant correlation with maturity and orientation and is about the same as those of dried cotton f

ISSN:0021-8995    

DOI:10.1002/app.1991.070430305

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

年代:1991

数据来源: WILEY

摘要:

AbstractTensile and impact properties of the ternary system polypropylene (PP)/ethylene propylene diene elastomer (EPDM)/glass fiber (GF) and the corresponding binary systems PP/EPDM blend and PP/GF composite are studied. Results are presented and analyzed as functions of compositional variables, viz., (i) matrix PP/EPDM blending ratio at constant GF loadings and (ii) GF loading at constant matrix blending ratios for the ternary system and (iii) EPDM content for PP/EPDM binary system and (iv) GF content for the binary system PP/GF, respectively. The role of individual components EPDM and GF in these mechanical properties is discussed and their combined effects are inspected at certain composition ranges. Theoretical analysis of tensile data is presented which reveals the effect of EPDM on the reinforcing effect of GF. Unlike the conventional role of an elastomer, increase of EPDM content in the presence of GF increases the modulus of the ternary system. Impact strength of the ternary system increases with increasing GF content both in the presence and absence of EPDM, showing a distinct minimum at matrix blending ratio PP/EPDM 90/10. Scanning electron micrographs of impact‐fractured surfaces are presented to illustrate the dispersion of the two phases of the polyblend matrix, fiber alignment, and the fiber interfac

ISSN:0021-8995    

DOI:10.1002/app.1991.070430306

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

年代:1991

数据来源: WILEY

摘要:

AbstractAromatic polyesters, prepared by the reaction of phthalic or isophthalic acids and α,ω‐alkanediols, were used to reduce the brittleness of bisphenol‐A diglycidyl ether epoxy resin cured with methyl hexahydrophthalic anhydride. These polyesters were effective as modifiers for toughening of the epoxy resin system. The most suitable composition for modification of the epoxy resins was inclusion of 20 wt % of poly(ethylene phthalate) (MW 7200), which resulted in a 150% increase in the fracture toughness (KIC) of the cured resin at no expense of its mechanical properties. The effectiveness of poly(alkylene phthalate)s as modifiers decreased with increasing the chain length of alkylene units. The toughening mechanism was discussed based on the morphological and dynamic mechanical behaviors of the modified epoxy resin s

ISSN:0021-8995    

DOI:10.1002/app.1991.070430307

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

年代:1991

数据来源: WILEY

摘要:

AbstractSimultaneous two‐component interpenetrating polymer networks (IPNs) of polyurethane (PU)–poly(methyl acrylate) (PMA) were prepared, as well as the corresponding pseudo‐IPNs. A comparison was made between the full IPNs, pseudo‐IPNs, and the respective homopolymers. Their ultimate mechanical properties were obtained and the dynamic glass transition temperatures (Tg's) were found using a thermomechanical analyzer. At all compositions, a singleTg(except 50–50 wt %)

ISSN:0021-8995    

DOI:10.1002/app.1991.070430308

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

年代:1991

数据来源: WILEY

摘要:

AbstractInterpenetrating polymer networks (IPNs) of polyurethane (PU)–polystyrene (PS) containing 50 wt % PU were synthesized at low temperature with varying crosslink density of each component. PU was polymerized first, followed by the photopolymerization of PS at low temperature (0 and 40°C). The theoretical molecular weight between crosslink (M̄c) of PU ranged from 8200 to 2050, and theM̄cof PS varied from linear to 2000. The degree of mixing of the components in these IPNs was investigated using dynamic mechanical analysis, electron microscopy, and density measurement. The degree of mixing increased with decreasingM̄cand/or synthesis temperature. The crosslink density variation at low synthesis temperature is more effective in enhancing the miscibility of IPN than at high synthesis temperature, because both the temperature and crosslink density can affect the polymer chain mobility during the synthesis. The variation of PU network crosslink density shows the better effect in increasing the miscibility of IPN than that of the PS network. The morphology and the density behavior agree well with the dynamic mechanical r

ISSN:0021-8995    

DOI:10.1002/app.1991.070430309

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

年代:1991

数据来源: WILEY

摘要:

AbstractPhotolytic degradation (350 nm) of acrylate‐type copolymer films in the presence of SO2and H2O has been examined using13C CP/MAS NMR. Copolymers in this study are used as binders in the paint and adhesives industry. The compositions contain butyl acrylate, vinyl acetate, vinyl chloride, and methyl methacrylate units in various combinations. Elemental analyses of the samples allow comparisons and confirmations of structural changes observed in the NMR spectra. A significant result is identification of pendant sulfate group incorporation in UV/SO2/or UV/SO2/H2O‐exposed VAc/BA‐type copolymers which has been attributed to a co‐unit interaction between BA and VAc units. It is suggested that effects onTg, the glass transition temperature, may account in part for this co‐unit effect on photode

ISSN:0021-8995    

DOI:10.1002/app.1991.070430310

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

年代:1991

数据来源: WILEY