摘要:

AbstractThe nitration capabilities of a range of chemical celluloses, including some containing the cellulose‐II polymorph, were examined. The cellulose samples, derived fromPinus radiatawood by bisulphite, prehydrolysis‐kraft or kraft pulping, were compared with a commercial nitration‐grade cellulose and two bleached cotton linters samples. All samples on nitration gave nitrocelluloses (degree of substitution ≈ 2–45) which had satisfactory stabilities and solubilities, with the exception of aP. radiatabisulphite cellulose which had a high pentosan value. The presence of cellulose‐II in the samples was not an impediment to the nitration. High performance size exclusion chromatography of the nitrocelluloses showed that the molecular weight distributions of samples derived from theP. radiatacelluloses were generally similar to that derived from a commercial nitration‐gr

ISSN:0959-8103    

DOI:10.1002/pi.4990250402

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractPermeation of individual gases through a low density polyethylene package film with CO2‐N2and CO2‐O2‐N2mixtures was simulated with a simple mathematical model. Permeabilities of carbon dioxide were of the order of 10−12m3/s m2atm/m with CO2‐N2systems. Including oxygen in the system did not change carbon dioxide permeabilities. Permeabilities of oxygen were of the order of magnitude of 10−9m3/sm2atm/m with this system. When a CO2‐O2‐N2mixture was humidified no substantial change was observed in CO2permeability, but the O2permeability decreased almost 10 times. These results and the mathematical model presented may help in the modified atmosphere package design to increase the shelf

ISSN:0959-8103    

DOI:10.1002/pi.4990250403

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractFriedel‐Crafts resins were prepared by reacting chloroacetyl chloride, 1,2‐dichloroethane and dichloromethane withm‐xylene using carbon disulfide as solvent and anhydrous AlCl3as catalyst. The resins were characterized by IR spectra and number average molecular weight measured by vapour pressure osmometry. The thermal properties were studied by thermogravimetry and differential scanning calorimetry. All the resins were tested for their microbial activity againstPseudomonas fluorescens, Bacillus subtilisandAspergillus niger.The results show that most of the resins can be used as bio

ISSN:0959-8103    

DOI:10.1002/pi.4990250404

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe kinetics of spherulite radial growth and the morphology of the compatible system PEO/PVC have been studied by optical microscopy.The usual spherulite radial growth behaviour has been found for compatible blends with PEO content higher than 70%. For lower composition, distortion of the usual spherulite morphology has been observed; the anomalies have been attributed to partial miscibility of the components.

ISSN:0959-8103    

DOI:10.1002/pi.4990250405

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe compatibilities of the systems poly(vinylidene chloride‐vinyl chloride 80:20)/polyadipate ester and poly(vinylidene chloride‐vinyl chloride 80:20)/tri‐isononyl trimellitate have been studied in the range 90–110°C using inverse gas chromatography (IGC). The retention behaviour of the polymer/plasticizer mixtures covering the entire composition range for each component was characterized for 10 probes of different chemical nature. In agreement with previous work, the IGC‐derived interaction parameters (X+23) showed an apparent dependence on the chemical nature of the probe, blend composition and temperature. The results predict good polymer/plasticizer compatibility up toc.0–40 weight fraction of plasticizer for poly(vinylidene chloride‐vinyl chloride 80:20)/polyadipate ester blends and toc.0.50 for poly(vinylidene chloride‐vinyl chloride 80:20)/tri‐iso‐nonyl

ISSN:0959-8103    

DOI:10.1002/pi.4990250406

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe reaction kinetics of irradiation‐prepolymerized MMA‐PU (polyether) IPNs have been studied by FTIR. The results indicate that the polymerization of each component in the IPN follows its normal distinct reaction mechanism with no mutual interference. Increasing the concentration of TMPTMA (crosslinking agent of PMMA) increased the formation rate of PMMA, while the formation rate of PU networks remained almost the same. Increasing the concentration of TMP (crosslinking agent of PU) increased the formation rate of PU, while the formation rate of PMMA networks decreased. The formation rate of PU was obviously faster than that of PMMA. A theory for the cage effect of the PU network has been propo

ISSN:0959-8103    

DOI:10.1002/pi.4990250407

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractItaconic anhydride was polymerized in the presence of a radical initiator under various conditions. The bulk polymerization at 75°C yielded polymer with molecular weight of more than 20000.The reactions of the resulting polymer with water and alcohols gave poly(itaconic acid) and its esters, respectively. The polymers prepared by such reactions were found to have similar thermal properties to those prepared by homopolymerizations of the respective itaconic acid derivatives.Poly(N‐substituted itaconomic acid)s, which are difficult to obtain by direct polymerization of their monomers, were prepared by the reactions of poly(itacononic anhydride) with amines.Copolymerizations of itaconic anhydride with electron‐donating monomers, styrene and isobutyl vinyl ether, gave alternating copolymers which were then converted by esterification to the respective copolymers of dialkyl itaconates with such electron‐donating mo

ISSN:0959-8103    

DOI:10.1002/pi.4990250408

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThermoset polyurethane (PU) elastomers were prepared using hydroxyl‐terminated polybutadiene (HTPB), toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). The effects of various diamines and diols on the mechanical and thermal properties of polyurethanes are discussed. The average molecular weight between crosslinks (M̄/c) was determined by swelling studies. The properties imparted by the extenders are explained on the basis of the groups present in the diamines and the number of methylene carbons in the dio

ISSN:0959-8103    

DOI:10.1002/pi.4990250409

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.4990250412

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.4990250415

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY