Copolymerization in the crystalline solid state

Herz, J.; Stannett, V.

doi:10.1002/pol.1968.230030101

Cited by 16 publications

(1 citation statement)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In such a case copolymers have been reported to arise in certain systems [51). However, only the overall composition of the resulting polymer was measured in most studies without any attempt to fractionate the reaction.…”

Section: ) the Role Ofcrystallite Boundariesmentioning

confidence: 99%

Initiation and Propagation Steps in the Solid State Polymerization of Vinyl Monomers

Chapiro

1972

Israel Journal of Chemistry

View full text Add to dashboard Cite

Several problems raised by initiation and propagation steps in solid-state polymerizations are reviewed on the basis of data taken from the literature as well as from unpublished work. The nature of the initial active centers is briefly considered; their addition to double bonds within the crystal is discussed. Examination of initiation yields in radiation-induced polymerizations shows that the efficiency of chain initiation rises with temperature. In most vinyl monomers, the propagation process, which is severely hindered in the crystal, presumably starts at lattice imperfections and thereafter proceeds on behalf of the additional imperfections introduced by the accumulated polymer. In a few specific cases the orientation of the double bonds in the crystal or their localization in certain regions of the crystal favours chain propagation and may result in a stereocontrolled reaction. The role of crystallite boundaries is emphasized particularly in the case of copolymerizations which take place in eutectic mixtures of two monomers.The polymerization of numerous monomers in the crystalline state has led to a large number of investigations in the past decade and a vast amount of experimental data is now available most of which are summarized and discussed in several review articles [1,2,3] . However, the detailed mechanisms of the individual reaction steps are still scarcely understood. It is the purpose of the present paper to consider some problems raised by the reaction steps in solid-state polymerization with the aim of providing a picture of possible mechanisms. It is clear that a complete analysis of this broad field cannot be covered in this discussion, which will be confined to a few aspects of initiation and propagation in crystalline vinyl monomers.

show abstract

Section: ) the Role Ofcrystallite Boundariesmentioning

confidence: 99%

Initiation and Propagation Steps in the Solid State Polymerization of Vinyl Monomers

Chapiro

1972

Israel Journal of Chemistry

View full text Add to dashboard Cite

show abstract

Viscosity index. III. Thermodynamic parameters for side chain crystallinity in pour point‐modified blends containing n‐octadecyl acrylate

Jordan

Smith

Zabarsky

et al. 1978

J of Applied Polymer Sci

View full text Add to dashboard Cite

SynopsisThe melting transitions and heats of fusion were obtained by differential scanning calorimetry for the crystalline phase of the same mixtures whose rheological properties were reported in the previous two papers. Pour point temperatures were also determined. In addition, the same thermodynamic quantities were also collected for higher polymer concentrations in this work, thus encompassing the entire concentration range. The DSC scans revealed that the distribution of crystallite sizes characteristic of the bulk copolymers was retained in the blends. Phase diagrams indicated isomorphism in all systems studied. An equation was derived to predict the influence of diluent concentration on melting point depression of copolymers, in which one component crystallizes through its side chains but in which the side chains of the other remain amorphous. The difference between the experimental heats of fusion and the value for entirely crystalline poly(n-octadecyl acrylate) were used to estimate extent of apparent cocrystallization of the different copolymers with the base oil. While this tended to increase with pour point-depressant ability, concomitant crystallinity of wax and depressant were essential to successful wax crystal modification. A mechanism is proposed in which whole molecules of hexagonally packed copolymers are attached to wax nuclei and accumulate slowly a t low diffusion rates. Thus, growth occurs over small crystal areas and is considered responsible for the directing influence of copolymer depressant. The resulting small crystal sizes, accompanied by fast growth of rapidly diffusing paraffins on uncontaminated surfaces, promote more compact habits, like dendri&s that postpone network formation to lower temperatures.It was concluded that a melting point difference of less than 25OC between bulk copolymer and base oil is required for successful pour point depression. Consequently, in this base oil, only copolymers with long amorphous side chains in a limited composition range, such as the n-octadecyl acrylate-2-ethylhexyl acrylate copolymers, possessed sufficient lattice disorder to meet the specification. The rest produced gelation at higher temperatures.

show abstract

Copolymerization of diacetylenes in the crystalline solid state. A method for recording latent fingerprints

Miller

Patel

1979

J of Applied Polymer Sci

View full text Add to dashboard Cite

Copolymerization in the crystalline solid state

Cited by 16 publications

References 33 publications

Initiation and Propagation Steps in the Solid State Polymerization of Vinyl Monomers

Initiation and Propagation Steps in the Solid State Polymerization of Vinyl Monomers

Viscosity index. III. Thermodynamic parameters for side chain crystallinity in pour point‐modified blends containing n‐octadecyl acrylate

Copolymerization of diacetylenes in the crystalline solid state. A method for recording latent fingerprints

Contact Info

Product

Resources

About