ISSN:0032-3888    

DOI:10.1002/pen.760191002

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760191003

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe early history of the use of the torsion pendulum in the investigation of polymers is described together with the development of dynamic mechanical testing at TNO. Examples are listed of studies of structure‐property relationships by means of the torsion pendulum. Techniques using supported. Samples are compared with those using unsupported samples, particular attention being paid to the advantages and restrictions of torsional braid analysis (TBA). The comprehensive application of TBA by Professor Gillham is reviewed; a few TBA results are compared with our torsion pendulum measurements. A rheologist's view on the so‐called liquid‐liquid transition (Tn) in polymer melts, as observed by TBA, is pres

ISSN:0032-3888    

DOI:10.1002/pen.760191004

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractA general model for thermosetting materials which relates polymerization to properties is discussed. In particular, a phase diagram relates the four states of matter encountered (i.e., liquid, rubber, ungelled glass and gelled glass) to gelation and vitrification phenomena. The model is extended to rubber‐modified thermosetting systems to show that, by control of the time to gelation, a given chemical formulation can provide different morphologies and hence different material behavior. The principal experimental approach uses a torsional braid analyze (TBA), an automated version of which is described. Use of the technique to measure gelation and vitrification times is discusse

ISSN:0032-3888    

DOI:10.1002/pen.760191005

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effect of cure history on the dynamic thermomechanical properties of a high temperature curing epoxy resin has been studied using torsional braid analysis. In isothermal cures “full cure” is not possible except at temperatures above the maximum glass transition temperature (Tg) of the cured resin, hence the necessity of a “post‐cure” after lower temperature isothermal cures. The highestTgand maximum cross‐linking in the cured resin was for a linear heating rate of 0.05°C/min from 30 to 200°C; higher heating rates lead to lower glass transition

ISSN:0032-3888    

DOI:10.1002/pen.760191006

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractTime/temperature cure profile diagrams of a nylon‐epoxy adhesive and a rubber‐modified epoxy based structural adhesive have been established from isothermal‐cure time torsional braid analysis measurements. The characteristic zones of liquid, gel‐rubber and glassy state behavior are noted on the diagrams. With the nylon‐epoxy adhesive, the time/temperature cure profile is ill‐defined since all the TBA data had to be obtained (due to the particular curing agent involved) at isothermal conditions above the glass temperature of the finally cured adhesive. In comparison, the rubber‐modified epoxy system showed distinct zones reflecting the various rheological states traversed during the thermosetting process. The dynamic mechanical. (Rheovibron), morphology, and adhesive joint strength properties are examined as a function

ISSN:0032-3888    

DOI:10.1002/pen.760191007

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractModem thermoset and coatings technologies provide the challenge of combining in situ polymer synthesis and processing with the task of characterizing an insoluble, intractable product. During the last dozen years several tools have been developed in J. K. Gillham's Princeton Laboratory which provide insight into this complex interrelationship. Although not necessarily conceived exclusively for thermoset characterization, these tools have been found to be uniquely suited to the task. To be discussed are the application of the torsional braid analyzer, a programmable pyrolyzer and thermal analysis to the study of coatings and thermosets in general. Also included is a discussion of a time‐temperature phase diagram for the thermoset analysis and the study of the formation of spiral and helical cracks in reinforced thermoset

ISSN:0032-3888    

DOI:10.1002/pen.760191008

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractAn instrumental system consisting of a combination of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, a gas chromatograph, a fast‐scan vaporphase infrared spectrophotometer and a computer is reviewed with examples which show the utility of the system in the analysis of decomposition phenomena in polyolefins, polyolefinsulfones, polymethacrylates, polystyrenes, and polybutadienes. The system records the thermal history before and during pyrolysis of the sample and provides chromatographic retention times, infrared spectra, mass numbers and relative amounts of the volatile products of pyrolysis. Identification of the constituents is thus facilitated and mechanisms for decomposition become easier to estimate and verif

ISSN:0032-3888    

DOI:10.1002/pen.760191009

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe use of inert supports for the study of mechanically weak polymer systems is becoming more widespread, particularly since Gillham established its acceptability in the torsional braid technique. A description and review of work using glass braid, glass filter mat and cellulose mat supports is presented. This consists of coverage of the dynamic mechanical response of a series of mono and di‐alkyl esters of polyitaconic acid ranging in ester chain length from C1to C18. The major features, e.g., glass and sub‐glass transitions, are identified and evidence of a double glass transition was found, when the ester chain length exceeds C6. The relaxations of ring systems in the glass phase are also examined. Controversy over the precise value ofTgfor amorphous polyethylene has continued for some time and our attempt to resolve the problem has centered on a study of hydrogenated polybutadienes. The data obtained support the proposition that the polyethyleneTgis about 195K and that its γ‐relaxation, suggested by some workers to be theTg, arises from crankshaft motion involving methylene sequences of 6 to 10 units. Other topics discussed include the damping characteristics of low molecular weight polymers such as poly(dimethylsiloxane), polystyrene, and poly(propylene oxide) with special reference to the existence ofTntrans

ISSN:0032-3888    

DOI:10.1002/pen.760191010

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe cellulose blotter/torsion pendulum technique used for the determination of relaxations that occur in low molecular weight compounds, oligomeric materials, and amorphous polymers is discussed. The glass transition temperature of a number of aliphatic alcohols and hydrocarbons have been determined and correlated with a method proposed by Gorskii in 1934. The glass transition temperature and molecular weight of these compounds follow the relationshipTg=BMarather thanTg=Tg(∞) ‐K/M. Although differences exist between the primary, secondary, and tertiary alcohols, they appear to follow a similar general pattern. In contrast, the hydrocarbons investigated have markedly different behav

ISSN:0032-3888    

DOI:10.1002/pen.760191011

出版商:Society of Plastics Engineers, Inc.    

年代:1979

数据来源: WILEY