摘要:

AbstractAntioxidants were attached to hydroxy‐terminated liquid natural rubber by modified Friedel‐Crafts alkylation reaction using anhydrous zinc chloride as catalyst. The rubber bound antioxidants were found to be less volatile and less extractable compared to conventional antioxidants. The bound antioxidants were tried both in latex compounds and dry rubber compounds. The vulcanizates showed improved ageing resistance compared to vulcanizates based on conventional antioxida

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930101

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractCurrent‐voltage characteristics of polycarbonate samples (PC) have been studied in the voltage range 50–1000 V. The effect of UV‐irradiation at λ = 225 and 300 nm, and thermal annealing on the electrical conductivity (σ) of PC was studied. The σ vs. 1/T relationship shows two slopes, i.e. two possible conduction mechanisms. The obtained results made it possible to determine a complete set of conduction parameters including activation energy and jump

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930102

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractTerpolymers of acrylonitrile (AN), vinyl acetate (VA) (7.5–30 mol‐%, related to AN), and divinylbenzene (DVB) (10 wt.‐%) were prepared by suspension polymerization. The diluents used were mixtures of toluene or cyclohexanol (90 vol.‐%) with solvents (10 vol.‐%) such as hexadecane (HD), octane (O), dodecane (D), 2‐ethylhexanol (E) or benzyl alcohol (B).It has been found that AN‐VA‐DVB terpolymers have a higher porosity, about 0.61–0.68, than corresponding AN‐DVB copolymers. The terpolymers obtained with mixtures of various diluents differ in their supermolecular structure although they had similar porosity characteristics.The thermal effects accompanying heating of the terpolymers above 200°C significantly exceed that of nitrile groups cyclization observed of t

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930103

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractLangkettige aliphatische Monothiirane können als reaktive Verdünner für Epoxidharze benutzt werden. Die Eigenschaften der ausgehärteten Produkte entsprechen denen, die bei der Verwendung von entsprechenden Monooxiranen (Monoglycidylethern oder ‐estern) gewonnen werden. Von Vorteil ist die Beschleunigung des Aushärtungsprozesses mit aliphatischen Polyaminen und Säureanhydriden sowie die geringere To

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930104

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractA high density polyethylene grade is blended with two selected grades of linear low density polyethylene and the mechanical and rheological properties of the blends are evaluated over the entire composition range. The blends show sufficient compatibility in the solid phase and in the melt and hence they can be advantageously used to capitalize on their useful properties.

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930105

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractIm Zuge der ionischen Modifizierung von Polymeren bieten sich elektroanalytische Charakterisierungsverfahren an. Die Palette der analytischen Probleme reicht dabei von der Bestimmung saurer oder basischer funktioneller Gruppen bis hin zur Quantifizierung reduzierbarer und oxidierbarer Spezies — und dies teilweise im spurenanalytischen Bereich. Praktisch relevante und theoretisch interessante Beispiele hierfür sind unter anderen die Ermittlung des Hydroxy‐Gruppengehaltes in Ethylen‐Vinylacetat‐Copolymeren und Epoxidharzen sowie die Bestimmung von als Restmonomerem vorliegenden Doppelbindungseinheiten in Acrylsäure‐Styrol‐Polypropylen‐Compounds und in Maleinsäureanhydrid‐Polyolefin‐Pfropfcopolymeren. Es werden konkrete Lösungsvarianten zu den genannten Problemstellungen beschrieben und die entsprechenden

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930106

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractDurch ringöffnende Polymerisation von Glycerinformal (GF) mit Alkalimetallen (M) in flüssigem Ammoniak konnten kationisch leitende Polymere (MxPGF) synthetisiert werden. Die Leitfähigkeiten κ hängen vom Alkoholatanteil im Polymeren ab. Na0,1PGF zeigt ein κRT= 3,75 · 10−4S/cm. Poly(glycerinformal)‐Alkoholate lassen sich mit CO2, CS2, oder SO2zu entsprechenden Halbestersalzen umsetzen. Das PGF‐O‐Sulfonat (NaSO2)0,1PGF ist bis 100°C thermostabil und hat ein κRT

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930107

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractA novel method of synthesizing a thiol‐terminated poly(L‐glutamic acid)IUPAC name: α‐hydro‐ω‐(2‐mercaptoethyl)amino‐poly{sodium imino‐[1‐(2‐carboxylatoethyl)‐2‐oxo]ethylene}.(PLGA) is reported. Synthesis of this compound is accomplished with the aid of a solid phase support. The procedure consists of first preparing aminoethyl disulfide‐functionalized silica, glass or polystyrene solid supports. The support thus prepared is then reacted with ester‐protected γ‐benzyl‐L‐glutamate or γ‐piperonyl‐L‐glutamate N‐carboxyanhydride (NCA) to obtain the conjugated poly(γ‐ester‐L‐glutamate)‐support. Then the protected ester group is acidolyzed by adding hydrobromic acid or trifluoroacetic acid (TFA). Finally, the disulfide bond of the resulting acid is cloven by reacting it with mercaptoethanol thus producing the desired end product,

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930108

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe interpenetrating polymer networks (IPNs) prepared from polyurethane (PU) and a glycidyl ether of phenol formaldehyde (GEPF) were synthesized by using a simultaneous polymerization method. The effects of PU molecular weight and amount on the mechanical property are discussed. For the PU/GEPF IPNs based on polyester‐type PU, as the PU content was increased, the tensile strength and fracture energy decreased, but the impact strength increased significantly. However, for the PU/GEPF IPNs based on polyether‐type PU, the extent of heterogeneity was decreased with decreasing molecular weight of polyether polyol in PU and the tensile strength and fracture energy were enhanced. The impact strength increased to a maximum value and then decreased when the PU content was further increa

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930109

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractCommercially available diethyl, dicetyl, and dimyristyl peroxydicarbonate initiators are investigated in a commercial PVC suspension polymerization receipe. Diethyl peroxydicarbonate, which is formed in situ by the reaction of hydrogen peroxide, lime, and ethylchloroformate, produced PVC with less “fish‐eyes”, whereas it has the disadvantage of being toxic and gives inconsistent polymerization times, therefore the reactor efficiency decreases. Dicetyl and dimyristyl peroxydicarbonates are solid, less toxic materials easy to handle, therefore, when these initiators are used, consistency between batches is obtained. However, PVC with coarse particle sizes containing considerable amounts of “fish‐eyes” is obtained, which eventually causes processing problems. It is found that particle coarsening occurs as a result of water soluble impurities of initiators, and “fish‐eyes” occur as a result of morphological changes. When dicetyl and dimyristyl type initiators are used, the number of non‐porous PVC particles increases. This structure heterogeneity causes formation of ungellified spots, so‐called “fish‐eyes”, during processing. It is found that the non‐porous particles are formed due to accumulation of an excessive amount of initiator in a single vinyl chloride monomer droplet.When the distribution of these solid initiators is homogenized by adding them in solution, the formation of non‐porous particles is inhibited. However, the coarsening effect still remains, which could be eliminated by extraction of initiator solutions with water just before they are fed to the reactor. Extraction also decrease

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051930110

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY