Time–humidity superposition in some crystalline polymers

Onogi, Shigeharu; Sasaguri, K.; Adachi, Tomio; Ogihara, Sadahide

doi:10.1002/pol.1962.1205816601

Cited by 47 publications

(42 citation statements)

References 16 publications

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“…D 0 (r) can be evaluated by using deformation e 0 (r) extrapolated for t = 0. In conformity with previous experience 11,18,[45][46][47] , Eq. (1) fits our experimental data over the whole period of measurements (Fig.…”

Section: D)supporting

confidence: 85%

Composites of alkaline poly(6-hexanelactam) with solid lubricants: one-step synthesis, structure, and mechanical properties

Horský¹,

Kolařı́k

Fambri

1999

Angew. Makromol. Chem.

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One‐step preparation of composites of alkaline poly(6‐hexanelactam) (PCL) with solid lubricants (SL), such as graphite and molybdenum disulfide, is an energy‐saving process as additional polymer fusion and melt mixing are not necessary. The initiator/activator system used were: (i) sodium dihydrido‐bis(2‐methoxyethoxo) aluminate (SYN)/cyclic trimer of phenyl isocyanate (PIC); (ii) sodium/hexamethylene‐1,6‐diisocyanate (HMDIC); (iii) SYN/HMDIC. These systems have been found suitable for the composite synthesis since they are relatively insensitive to traces of humidity and other low‐molar‐mass compounds which may be adsorbed on lubricant surfaces. Incorporated graphite (up to 20 wt.‐%) and MoS2 (up to 40 wt.‐%) do not perceptibly affect glass transition temperature, melting temperature and crystallization temperature while polymer yield, polymerization degree and rate decrease. The crystallinity assessed by DSC passes through a maximum at 20% of MoS2 in contrast to that detected by X‐ray diffraction (XR) measurements. As expected, the mean spherulite diameter drops profoundly. Both SL affect mechanical properties of produced composites: (i) increase the modulus; (ii) decrease the compliance, the time dependence of which remains close to that observed for the matrix; (iii) reduce the yield strength; (iv) slightly lower the impact strength of composites. A tentative hybrid composite containing 15 wt.‐% of graphite, 5 wt.‐% of MoS2, and 5 wt.‐% of mineral oil (as a liquid lubricant) shows a modulus high enough and its propensity to creep is not enhanced. The observed changes in mechanical properties of PCL caused by the incorporation of SL do not preclude applications analogous to those of unfilled PCL. Friction properties of the composites were beyond the scope of this work.

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Section: D)supporting

confidence: 85%

Composites of alkaline poly(6-hexanelactam) with solid lubricants: one-step synthesis, structure, and mechanical properties

Horský¹,

Kolařı́k

Fambri

1999

Angew. Makromol. Chem.

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“…(1) suits better our experimental data, we have used the values of K and n to characterize the creep dependences of both PCL and PCL composites (Tab. 2) at a constant temperature and moisture content 8,[41][42][43] . As can be seen, parameter n is closely related to the creep rate:…”

Section: Structure and Mechanical Properties Of Compositesmentioning

confidence: 99%

Composites of alkaline poly(6-caprolactam) and short glass fibers: one-step synthesis, structure and mechanical properties

Horský¹,

Kolařı́k

Fambri

1999

Angew. Makromol. Chem.

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If incorporation of short fibers precedes the polymerization process, their damage is reduced because the viscosity of a monomer is much lower than that of a corresponding polymer. One‐step preparation of composites also leads to essential energy savings since polymer fusion and melt mixing are eliminated. Structure and properties of poly(6‐caprolactam) matrix polymerized with the initiator/activator systems sodium dihydridobis(2‐methoxyethoxo)aluminate/cyclic trimer of phenyl isocyanate are affected by rising concentration of (γ‐aminopropyl)triethoxysilane sizing agent: polymerization is slower, but polymerization degree rises; yield strength and notched impact strength decrease, while crystallinity and modulus remain unaffected. When the initiation system sodium tetra(6‐caprolactamo)aluminate/cyclic trimer of phenyl isocyanate is alternatively used, the polymerization is somewhat faster, but the polymer is insoluble in m‐cresol due to side crosslinking reactions. Incorporated short glass fibers (SGF) (up to 13.2 vol.‐%) do not markedly affect the matrix properties. As expected, SGF decrease the compliance (increase the moduli) of composites, but do not affect the time dependence of the creep. Increasing the fraction of SGF also decreases the yield strength of composites, which indicates poor interfacial adhesion; the latter is only slightly improved by fiber sizing. Impact strength decreases with the fraction of as‐received SGF, while a moderate opposite trend can be seen for the composites containing silane treated fibers.

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“…Although stress relaxation must also be taken into account, it occurs relatively slowly and is small in moist nylon 6. 12 Hence it was ignored in this calculation. With these data, eq.…”

Section: Length Variationmentioning

confidence: 99%

Swelling of nylon 6 film due to water sorption

Inoue

Hoshino

1976

J. Polym. Sci. Polym. Phys. Ed.

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Dimensional changes in nylon 6 film on absorption and desorption of water were studied as functions of time and the amount of absorbed water. For absorption, a plot of film expansion versus the square root of time was sigmoidal in the initial region and did not coincide with the sorption curve: the latter was linear in the same region. This behavior is very similar to that reported for nylon 6 fiber by Kunzman. A theoretical analysis based on certain assumptions about the molecular state of nylon 6 gave good agreement with experimental results. By this analysis it was shown that the characteristic swelling behavior arises from instantaneous relaxation of the polymer molecules and is not connected with a time lag between water absorption and expansion of the polymer, as Kunzman proposed.

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Time–humidity superposition in some crystalline polymers

Cited by 47 publications

References 16 publications

Composites of alkaline poly(6-hexanelactam) with solid lubricants: one-step synthesis, structure, and mechanical properties

Composites of alkaline poly(6-hexanelactam) with solid lubricants: one-step synthesis, structure, and mechanical properties

Composites of alkaline poly(6-caprolactam) and short glass fibers: one-step synthesis, structure and mechanical properties

Swelling of nylon 6 film due to water sorption

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