8.2 Template Crystallization: Dynamic Mechanism …
147
‘induction time’ is used for a preparatory process in which something absolutely
unknown is happening. Since the happenings are clearly explained and logically
rational in the present case, it should not be called an induction time per the usual
scientific common sense.
8.2.3 Prospective Comments on a Kinetic Modeling
of Template Crystallization
Different from nucleation, SIC initiated by a template is more or less similar to
template polymerization [1, 78], which is originated from the solid-state synthesis
of polypeptides developed by Merrifield [79, 80]. He later won the Nobel Prize of
Chemistry in 1984, and Ref. [79] is one the most cited articles among the papers
appeared in J. Am. Chem. Soc. The template polymerization is quite common in
biochemical syntheses: For example, our DNA is accurately reproduced using our
parents’ DNA as a template.
Taking the elementary reactions of template polymerization into account [1, 39,
40], a series of possible elementary steps of template crystallization are proposed
as shown in Fig. 8.6. The S in the figure designates a monomer unit or a segment,
depending on the theoretical background of the employed evaluation method. If a
molecular dynamic treatment is to be used, S can be a monomer unit. Or, for a
rheological study, it may be more convenient to assume S to be a segment.
For the benefit of future kinetic studies, a detailed remark is to be given on each step
as follows:
(1) Step one shows the fully extended chain formed by tensile elongation of the
rubbery sample. The extended chain has to have an enough length in order
to function as a template for the crystallization. Since both chain ends are not
much movable by the cross-linking, the micro-Brownian motion of the templates
is practically arrested, and it is assumed to be immobile. The length is to be
estimated: For a moment, a length of the chain enough to form a helix is a
possible candidate, and a length equivalent to the thickness of lamella in polymer
crystal is another possibility. The former may be minimal and the latter maximal
for the template crystallization are a probable length range, too. Further, it is
noted again that the formation of the fully extended network chains in the NR
vulcanizate by its uniaxial tensile elongation is not a stochastic process, but a
deterministic process under the concepts of cause and effect in accordance with
the classic causality relationship.
(2) In step 2, a nearby oriented amorphous chain of the longer length than the
template diffuses near to the template by the micro-Brownian movement. The
longer is the network chain, the more active is its micro-Brownian motion in
the rubber vulcanizates. Probability of the nearby presence of network chains
of almost the same length as the template is not high. Hence, the template is
assumed to be composed of a single chain, not of an assembly of template chains.
147
‘induction time’ is used for a preparatory process in which something absolutely
unknown is happening. Since the happenings are clearly explained and logically
rational in the present case, it should not be called an induction time per the usual
scientific common sense.
8.2.3 Prospective Comments on a Kinetic Modeling
of Template Crystallization
Different from nucleation, SIC initiated by a template is more or less similar to
template polymerization [1, 78], which is originated from the solid-state synthesis
of polypeptides developed by Merrifield [79, 80]. He later won the Nobel Prize of
Chemistry in 1984, and Ref. [79] is one the most cited articles among the papers
appeared in J. Am. Chem. Soc. The template polymerization is quite common in
biochemical syntheses: For example, our DNA is accurately reproduced using our
parents’ DNA as a template.
Taking the elementary reactions of template polymerization into account [1, 39,
40], a series of possible elementary steps of template crystallization are proposed
as shown in Fig. 8.6. The S in the figure designates a monomer unit or a segment,
depending on the theoretical background of the employed evaluation method. If a
molecular dynamic treatment is to be used, S can be a monomer unit. Or, for a
rheological study, it may be more convenient to assume S to be a segment.
For the benefit of future kinetic studies, a detailed remark is to be given on each step
as follows:
(1) Step one shows the fully extended chain formed by tensile elongation of the
rubbery sample. The extended chain has to have an enough length in order
to function as a template for the crystallization. Since both chain ends are not
much movable by the cross-linking, the micro-Brownian motion of the templates
is practically arrested, and it is assumed to be immobile. The length is to be
estimated: For a moment, a length of the chain enough to form a helix is a
possible candidate, and a length equivalent to the thickness of lamella in polymer
crystal is another possibility. The former may be minimal and the latter maximal
for the template crystallization are a probable length range, too. Further, it is
noted again that the formation of the fully extended network chains in the NR
vulcanizate by its uniaxial tensile elongation is not a stochastic process, but a
deterministic process under the concepts of cause and effect in accordance with
the classic causality relationship.
(2) In step 2, a nearby oriented amorphous chain of the longer length than the
template diffuses near to the template by the micro-Brownian movement. The
longer is the network chain, the more active is its micro-Brownian motion in
the rubber vulcanizates. Probability of the nearby presence of network chains
of almost the same length as the template is not high. Hence, the template is
assumed to be composed of a single chain, not of an assembly of template chains.