All issues
Successor
Predecessor
Volume 21, Issue 233
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
I.“Formaldehyde Isolation Test” as the Method for Determining the Degree of Cure of Melamine-Formaldehyde ResinMikio Nakajima1964 Volume 21 Issue 233 Pages 529-538
Published: September 25, 1964
Released on J-STAGE: October 14, 2010
JOURNAL FREE ACCESSA method for determining the degree of cure of melamine-formaldehyde resin and factors influencing the test were studied on laminate.
A test piece (30-50mm) was dipped into 50ml of water or dilute sulphuric acid at various temperatures (60-100°C) and times (3-80min).
Formaldehyde and melamine were dissolved in the solution due to the dissociation of methylol and the decomposition of methylene groups.
Formaldehyde dissolved into 0.95-3.03% sulphuric acid at 100°C for 10min was almost attributed to the remaining methylol groups in hardened resin, therefore, the amount of formaldehyde indicated the relative degree of cure of resin.
Among the factors on “formaldehyde isolation test”, curing temperature was more effective than curing time, and pressure was no effect.
The activation energies of the dissociation of methylol and the decomposition of methylene groups were ca. 20 and 29kcal/mol, respectively.View full abstractDownload PDF (1952K) -
II. Comparisons of “Formaldehyde Isolation Test” with Other Methods for Determining the Degree of Cure on Melamine-Formaldehyde ResinMikio Nakajima1964 Volume 21 Issue 233 Pages 538-544
Published: September 25, 1964
Released on J-STAGE: October 14, 2010
JOURNAL FREE ACCESSComparisons of “formaldehyde isolation test” with other methods for determining the degree of cure (the transition of Rockwell hardness with temperature, differential thermal analysis, the estimation of condensation water in hardened resin, etc.) were studied.
As the results, it has been found that the values obtained by “formaldehyde isolation test” are proportinal to the amount of remaining methylol groups in hardened resin, and indicate the good correlation to the values obtained by the other methods.
Therefore, “formaldehyde isolation test” is useful for determining the degree of cure of hardened resins (in C-Stage).View full abstractDownload PDF (1230K) -
III. Relations between the Degree of Cure of Melamine-Formaldehyde Resin and the Curing Conditions, and Kinetics of Condensation at C-StageMikio Nakajima1964 Volume 21 Issue 233 Pages 544-552
Published: September 25, 1964
Released on J-STAGE: October 14, 2010
JOURNAL FREE ACCESSThe relations between the degree of cure (the value obtained by “formaldehyde isolation test”) and the curing conditions were studied on melamine-formaldehyde resin laminates.
The rate equation for hardening of resin in C-stage was proposed and the apparent activation energy was ca. 20.5 kcal/mol.
Further, the effect of catalyst on curing temperature and time was studied quantitatively.
Main experimental equations were shown below.
The notations are
F: degree of cure (mg/100cm2)
T, (Tc): curing temperature (°K), (when using catalyst)
t, (tc): curing time (min), (when using catalyst)
C: catalyst added in varnish (%) a, a′, a″, k1, k1′, k1″, k2, k2′, k2″, α, β, γ, δ, to: const.View full abstractDownload PDF (1478K) -
Copolymers Including Both Branching Agent and Chain-TerminatorItaru Nakamura, Rei Yokouchi, Tadao Ito, Daisuke Miura, Ken-ichi Fujii1964 Volume 21 Issue 233 Pages 553-563
Published: September 25, 1964
Released on J-STAGE: October 14, 2010
JOURNAL FREE ACCESSThe molecular distribution of a complicated polyfunctional condensation copolymer has been calculated according to the distribution theory of W. H. Stockmayer. The model system is fundamentally 2-2 functional, small amounts of both monofunctional (A1) and tetrafuctional (A4) compounds being used at the same time.
When 1mol% of A1 and 0.2mol% of A4 are employed in this system and a reaction rate of 99% is assumed, 59.8% of the all polymer molecules is homopolymer including neither A1 nor A4; while 93.7% is linear molecules with no A4 unit. The sums of distribution equation diverge when larger amount of A4 is added, the fact corresponding to gel formation.
Equal reactivity of all functional groups of one kind and no side reaction such as intramolecular condensation have been assumed.View full abstractDownload PDF (1782K) -
Ichiro Sakurada, Yasuyoshi Sakaguchi, Yasuhiro Omura1964 Volume 21 Issue 233 Pages 564-567
Published: September 25, 1964
Released on J-STAGE: October 14, 2010
JOURNAL FREE ACCESSPolyvinyl alcohols were acetalized with aldehyde sulfonic acids such as β-butyraldehyde sulfonic acid, o-benzaldehyde sulfonic acid and 2, 4-benzaldehyde disulfonic acid in solution. The maximum conversions of the reactions were generally much lower than the calculated value from Flory's theory, and dependent on the steric configurations of polymer and the compositions of the reaction mixtures. Steric hindrance and/or electrostatical effects by acetals introduced into the polymer chains seem to be the reasons for these results. Statistical calculations were given for the maximum conversions.View full abstractDownload PDF (1042K) -
1964 Volume 21 Issue 233 Pages 576
Published: 1964
Released on J-STAGE: October 14, 2010
JOURNAL FREE ACCESSDownload PDF (148K)
- |<
- <
- 1
- >
- >|