Crystallization in High Polymers. VII. Heat of Fusion of Poly-(N,N'-sebacoylpiperazine) and its Interaction with Diluents<sup>1</sup>

Flory, Paul J.; Mandelkern, L.; Hall, H. K.

doi:10.1021/ja01150a035

Cited by 81 publications

(37 citation statements)

References 3 publications

(4 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Up to temperatures of about 35° C, volume equilibrium appeared to be attained simultaneously with temperature equ ilibrium, and the specific volume varied linearly with temperature. This is in marked contrast to other polymers [2,6,8,10], in whirh partial melting and recrystallization always occur in the temperature range below the equilibrium melting temperature. At a given temperature above 35° C the volume of the stark rubber samples no longer remained invariant with time, but was observed to increase slowly.…”

Section: Chemical Analysescontrasting

confidence: 66%

“…Descriptions of the volume dilatometers employed and the procedures followed have been published [6,10]. The dilatometers were immersed in constant-temperature baths controlled within ±0 .1 deg C. The thermal histories of the samples and the times held at the various temperatures are detailed below.…”

Section: Methodsmentioning

confidence: 99%

“…The melting behavior of the four stark rubber samples was investigated. Because of time effects above 35° C, a revision was required in the heating schedule that has been used with ordinary natural rubber [8] and other polymers [2,6,10]. The observations were initiated at abou t 15° C, and the temperature was raised at the rate of 1 deg each 12 to 24 hours.…”

Section: Chemical Analysesmentioning

confidence: 99%

“…For many polymers, including natural rubber, it has been observed that the mel ting temperature Tm , depends on the crystallization temperature whe~ the heating rate is relatively rapid [4 ,5,6,7J . However, for polyesters [5], polyamides [6], and more recently for natural rubber [8], it has been demonstrated that when slow heating rates are employed the melting temperature observed is independent of previous thermal history and then the equilibrium melting t.emperature is appro3:ched. This heating schedule I S presumably condUCive to the formation of more perfect crystallites, which are stable at higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Nature of stark rubber

Roberts¹,

Mandelkern²

1955

J. RES. NATL. BUR. STAN.

Self Cite

View full text Add to dashboard Cite

TI;,e melting behavior: and X-ray diffrac.tion patterns of four different samples of "stark rubbel: have been Illvestigated. The meltmg temperatures, 39° to 45 .5° C, a re s ubstantially hif?her than th.at .observed for natural. rub.ber crystallized by coo ling. The X-ray d iffractIOn patterns 1I1clicate that the crystallites 111 stark rubber are oriented. This observati.op ~an ex plaip the higher meltin~ temperatures. Thus, t he prev ious assignment of an eq UIlibrium melt1l1g temperature, 28 ± 1° C, to unoriented crystalline natural rubber is shown. to be appropriate. Several different methods that have been used successfully in prepanng stark rubber under controlled conditions in the laboratory are outlined.

show abstract

Section: Chemical Analysescontrasting

confidence: 66%

Section: Methodsmentioning

confidence: 99%

Section: Chemical Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nature of stark rubber

Roberts¹,

Mandelkern²

1955

J. RES. NATL. BUR. STAN.

Self Cite

View full text Add to dashboard Cite

show abstract

“…14,15 The phase separation curve in the repulsive system, where there is no attractive interaction between oligomers and solvents, can be written as the combination of the freezing point curve of the oligomers and the upper critical solution temperature type consolution curve. Aromatic polymers discussed here are usually prepared by the step-growth polymerization represented by polycondensation reaction.…”

Section: Reaction-induced Phase Separation Of Oligomers During Solutimentioning

confidence: 99%

Morphology Control of Aromatic Polymers in Concert with Polymerization

Kimura

Kohama

Yamazaki

2006

Polym J

View full text Add to dashboard Cite

ABSTRACT:Morphology control methods of aromatic polymers in concert with polymerization reaction are described in this review. Many attractive methods have been developed including reaction-induced phase separation of oligomers, epitaxial polymerization, shear-induced chain orientation during gelation, template-based polymerization, suspension polycondensation, solid-state polycondensation and liquid-liquid interfacial precipitation and so on. Among them, the reaction-induced phase separation of oligomers, in which there are two modes of crystallization and liquidliquid phase separation, possess practically high potentiality to create novel polymer materials since it can control not only the morphology but also the molecular chain orientation. Ultimate goal is the embodiment of the nature system in a flask, that is, the control of the materials from primary structures to super structures. The morphology control methods by using polymerization reaction afford the valuable methodology for the three-dimensional structure architecture.[doi:10.1295/polymj.PJ2006083] KEY WORDS Morphology / Phase Separation / Oligomer / Whisker / Microsphere / Epitaxy / Aromatic Polymer / Morphology of polymer materials is of great importance as well as the molecular chain orientation for the creation of new functional and high-performance materials possessing essential properties predicted from their molecular structures. From the both aspects of molecular chain orientation and morphology, one of the ideal materials is a needle-like single crystal of extended molecular chains called polymer whisker. Especially, wide variety of polymeric nanomaterials is required for supporting nanotechnology and the more precise controls are rapidly necessitated in these days. Hence, the demand for the morphology control method increases significantly. Usually, extended molecular chain crystals are difficult to obtain by conventional processing methods and the special processing techniques have been developed thus far.1 There exists another stream for the development of extended molecular chain crystals by means of crystallization during polymerization. The needle-like crystals of both flexible and rigid polymers have been obtained by the solid-state polymerization of the monomers and the polymerization in the solution. Examples of the former polymerization have included oxacyclobutanes such as 1,3,5-trioxane, 2,3 diolefins undergoing four-center type photopolymerization 4,5 and monomers with conjugated triple bonds such as substituted diacetylenes.6,7 On the other hand, the first polymer whisker was obtained by the cationic ring-opening polymerization of 1,3,5-trioxane. [8][9][10] The obtained polyoxymethylene whiskers were 1-2 mm in width and 10-50 mm in length. The molecular chains aligned along the long axis of the whisker. They were brought into practical uses with its unique morphology and good mechanical properties.11,12 However, the polyoxymethylene whisker has a melting temperature at 180 C and the low melting temperature limits the broader c...

show abstract