Polycaprolactam filled with short glass fibres and microbeads. I. Preparation of composites by anionic activated adiabatic polymerization

Fambri

1999

Angew. Makromol. Chem.

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.

Section: Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Horský¹,

Fambri

1999

Angew. Makromol. Chem.

“…The polymerization was carried out under nitrogen in a stainless steel vessel, electrically heated and equipped with a stirrer, thermocouples and an electronic system to control the adiabatic conditions 10,23) . The diameter and height of the polymer blocks (about 1 kg) were ca.…”

Section: Synthesismentioning

confidence: 99%

“…The initiator/activator system SYN/PIC = 0.3 mol-%/0.3 mol-% was selected for composite materials with regard to previous results [10][11][12][13] . Tab.…”

Section: Structure Of the Pcl Matrixmentioning

confidence: 99%

“…This procedure is used also for poly(6-caprolactam) (PCL) and other polyamides so that various types of polyamide composites reinforced with short glass or carbon fibers are commercially available 4,8) . Alternatively, the incorporation of particulate fillers 9) or short fibers [10][11][12][13] may precede the polymerization process. In this way, the damage (breaking and shortening) of short fibers is reduced because the viscosity of a monomer is much lower than that of a corresponding polymer.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Horský¹,

Fambri

1999

Angew. Makromol. Chem.

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.

Polycaprolactam filled with short glass fibres and microbeads. II. Elastic and ultimate properties of composites prepared by the anionic adiabatic polymerization

Horský

1985

Acta Polymerica

Self Cite

HORSKP and KOLAMK: Polycaprolactam filled with short glass fibres and microbeads. I1 Table 4. -1 diabatic polymerization of caprolnctain with glass -Wt.% "C "C 1/1.5 32.7 142 209 15 40 95.8 573 0.384 l ) Polymerization was initiated with the system 0.3 mole-% Synhydrid and 0.3 mole-% phenyl isocyanate trimer; corrected initial polymerization temperature was Tocor = 135 + ATps (in "C) 2, Fibres and beads of average length 1, = 0.20 mm and diameter d , = 0.15 mm, respectively, were coated with 1.4 and 0.05 wt.% of y-aminopropyltriethoxysilane, respectively 3, Masimal temperature reached in the polymerization including crystallization 4, Polymerization halftime s, Time needed for reaching T,,,