Anionic polymerization of caprolactam. XLIII. Relationship between osmometric molecular weight, viscosity, and endgroups of a polymer

Goebel, Carol V.; Čefelín, P.; Stehlı́ček, J.; Šebenda, J.

doi:10.1002/pol.1972.150100512

Cited by 54 publications

(9 citation statements)

References 26 publications

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“…Figure 3 shows viscometric-average molecular weight (M v ) versus yield dependences for e-caprolactam polymerization using N-acetyl-e-caprolactam/ CL 2 Mg/MgCl 2 initiating system at different temperatures. Note, that viscometricaverage molecular weight was determined using relationships derived for the anionic poly(e-caprolactam) and calibrated as a number-average by membrane osmometry [5,36]. Therefore, assuming the similar molecular weight distribution for poly(e-caprolactam)s prepared in this study, we can conclude that M v is close to number-average molecular weight (M n ).…”

Section: Mg/mgcl 2 As Initiatormentioning

confidence: 97%

“…The intrinsic viscosity of the obtained polymers was measured in m-cresol at 25 ± 0.1°C using an Ubbelohde viscosimeter. The viscometric-average molecular weights (M v ) were calculated using the following equation: [g] = 7.44 9 10 -4 9 M v 0.745 [5,36]. Thermogravimetric analysis (TGA) was performed on a TGA51 TA Instruments apparatus between 20 and 550°C under nitrogen with a heating rate 10°C min -1 .…”

Section: Polymer Characterizationmentioning

confidence: 99%

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Activated anionic ring-opening polymerization of ε-caprolactam with magnesium di(ε-caprolactamate) as initiator: effect of magnesium halides

et al. 2011

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The activated anionic ring-opening polymerization of e-caprolactam initiated by 0.35 mol% of combined initiator, i.e., equimolar mixture of magnesium di(e-caprolactamate) (CL 2 Mg) with magnesium halides (MgCl 2 , MgBr 2 , and MgI 2 ) as well as of e-caprolactam magnesium bromide (CLMgBr) in the presence of 0.35 mol% of N-acetyl-e-caprolactam as an activator has been investigated in the temperature range 140-200°C. It was found that the reaction rate increased while the apparent activation energy decreased in the following series: CL 2 Mg/ MgCl 2 \ CL 2 Mg/MgBr 2 * CLMgBr \ CL 2 Mg/MgI 2 . In addition, the poly(ecaprolactam)s prepared with CL 2 Mg/MgX 2 (MgX 2 = MgCl 2 , MgBr 2 , and MgI 2 ) are characterized by slightly higher thermal stability than polymers obtained with CLMgBr as initiator. These observations were explained in terms of the coordination of Lewis acids (MgX 2 , where X = Cl, Br, and I) with imide carbonyl of N-acyllactam end groups leading to the increase of their reactivity and stability.

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Section: Mg/mgcl 2 As Initiatormentioning

confidence: 97%

Section: Polymer Characterizationmentioning

confidence: 99%

Activated anionic ring-opening polymerization of ε-caprolactam with magnesium di(ε-caprolactamate) as initiator: effect of magnesium halides

et al. 2011

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“…The degree of polymerization was determined from viscosity measurements in m-cresol solutions 28) . The percentage of water-extractable monomer and oligomers (WEM) was evaluated as the mass difference between the as-received specimen and the extracted (in boiling water for 30 h) and re-dried specimen.…”

Section: Sample Characterizationmentioning

confidence: 99%

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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“…The rate of polymerization characterized by the polymerization halftime t 0.5 (time for reaching p = 0.5) was calculated by using the time record of temperature registered in the course of polymerization. The degree of polymerization P was determined from viscosity measurements in m-cresol solutions 24) . Polymer density at 20 8C was assessed by the flotation method using a CCl 4 /toluene system.…”

Section: Sample Characterizationmentioning

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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Anionic polymerization of caprolactam. XLIII. Relationship between osmometric molecular weight, viscosity, and endgroups of a polymer

Cited by 54 publications

References 26 publications

Activated anionic ring-opening polymerization of ε-caprolactam with magnesium di(ε-caprolactamate) as initiator: effect of magnesium halides

Activated anionic ring-opening polymerization of ε-caprolactam with magnesium di(ε-caprolactamate) as initiator: effect of magnesium halides

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

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