摘要:

The actual status of the heat and light stabilization of PVC is reviewed with emphasis on the stabilizers and their mode of action.

ISSN:0022-233X    

DOI:10.1080/00222337808061383

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A brief summary of secondary processes in PVC thermal degradation is given. This includes some details of crosslinking and gel formation, cyclization, chain scission and benzene formation, Diels-Alder reaction with additives, as well as oxidation of polyenes.

ISSN:0022-233X    

DOI:10.1080/00222337808061384

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

4-Chloro-2-hexene can be considered a model compound for the chlorinated allylic structure appearing in PVC chains after dehydrochlorination. This model compound was used to elucidate the mechanism of reaction of primary or secondary stabilizers.

ISSN:0022-233X    

DOI:10.1080/00222337808061385

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Stabilizers, R2SnX2, react with allylic chlorine atoms during the induction period and also absorb HC1 to give XH molecules which add to double bonds. Changes in R which facilitate Sn-C bond cleavage are unfavorable, but γ-carbonyl groups are beneficial.

ISSN:0022-233X    

DOI:10.1080/00222337808061386

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Prof. D. A. Smith (Univeristy of London, Great Britain): My question is rather general, and although it is directed to Dr. Wirth, it is probably also directed to all authors who quote “induction periods.” I am not doubting that there are induction periods when stabilizers are used. I am concerned, however, with the accurate measurement of an induction period when curves are asymptotic, or nearly so, to the time axis. It is common in chemical kinetics, where the kinetic form of reaction curves can be described accurately, to fit them to data points at higher extents of conversion, extrapolating back to the time axis in order to measure accurately an intersection point which will be a real induction period. Could Dr. Wirth say whether this is yet possible in stabilizer technology, or can anyone else comment on possible kinetic treatments?

ISSN:0022-233X    

DOI:10.1080/00222337808061387

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Stabilization of polyvinyl chloride) (PVC) containing metal soaps was investigated by psychophysical colorimetry. A color difference observed among heated PVC films containing various metal salts depends on coloration of the π-complex of polyene with metal chloride converted from the metal salt added and that the stabilization effect of synergistic soaps should be based on an effect of complementary colors set up among a polyene color and metal chloride-polyene complex colors. These conclusions are well supported by colorimetry of heated PVC films containing various dyes. The color of heated PVC films containing Zn/Ca and Cd/Ba synergetic soaps markedly deviated from a polyene color with increased heat treatments, owing to greater degree of coloration of Zn complex and Cd complex, respectively. These color deviations usually decrease the thermal stability of PVC. The thermal stability of PVC was markedly improved by the use of synergetic soaps together with masking agent such as triethanolamine, urea, N,N′-dimethylol-urea, and vinylpyridine-methylmethacrylate copolymer, owing to the masking effect of these nitrogen-containing compounds. These masking agents did not slow down the dehydrochlorination of PVC.

ISSN:0022-233X    

DOI:10.1080/00222337808061388

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The consumption of stabilizers based on organic soaps with Cd/Ba molar ratios of 3, 2, and 0.4, respectively, and with a molar ratio of Ca/Zn of 1 during thermal treatment of polyvinyl chloride) mixtures in a degradation apparatus, in a press, and in the mixing cavity of a Brabender Plastograph has been investigated on the basis of determination of chlorides by coulometric titration. The thermal stability of the mixtures has been calculated from the hydrogen chloride evolved, as found by a potentiometric method. It was found that the stabilizer was not fully consumed when the residual thermal stability reached zero. The formation of chlorides in the stabilized mixtures was slower than the hydrogen chloride evolution from the original unstabilized polymer.

ISSN:0022-233X    

DOI:10.1080/00222337808061389

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The mechanism of reaction of the β-aminocrotonate of butanediol (βACB) with 4-chloro-2-hexene (4C2H), a model compound for the allylic chlorine in polyvinyl chloride), was studied in THF or dichloroethane at 60°C by gas and liquid chromatography. The reaction, which needs ZnCl2as a catalyst, leads to substitution products through the primary amine group and the hydrogen atom of the trisubstituted double bond. βACB reacts with HCl to give NH4Cl and a set of complex organic products. NH4Cl and the substitution products are able to complex ZnCl, inhibiting its catalytic activity. In combination with other stabilizers, βACB strongly induces the substitution reaction versus the dehydro-chlorination. In the polymer at 190°C, it increases very much the time of action of the stabilizers; it acts as an HC1 acceptor but also it may be substituted on the polymer even without catalysts. Synergistic effects are observed with epoxy compounds or indole derivatives.

ISSN:0022-233X    

DOI:10.1080/00222337808061390

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Phenol-formol prepolymers (novolak resins) fully epoxidized, with a molecular weight around 1000, can be mixed with other powdered compounds in stabilization formulation for poly(vinyl) chloride). They can replace epoxidized soyabean oil, with improvement of the Vicat softening point of rigid fabrics. A number of examples are given.

ISSN:0022-233X    

DOI:10.1080/00222337808061391

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

An eutectic mixture of sodium and potassium nitrites and nitrates which is liquid at the processing temperature is proposed as a new efficient stabilizer for PVC.

ISSN:0022-233X    

DOI:10.1080/00222337808061392

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor