Investigation on the spinnability of metallocene cyclic olefins copolymer melt

Abstract

This work investigates the melt spinning process of the metallocene cyclic olefins copolymer (mCOC), which had never been successfully developed before. The shear-viscosity examination reveals that the mCOC has a mild shear thinning tendency due to the presence of cyclic olefins, but is very sensitive to the temperature variation. The optimal melt extrusion temperature for the mCOC is found between 320 and 330°C. The mCOC is known to have high Tg, which would cause early solidification, seriously broken filaments, and winding interruption during the melt spinning process. Accordingly, the traditional spinning process employing an air-quenching system at 18°C for polyolefins, such as polypropylene and polyethylene, is inappropriate for the mCOC. Experimental results reveal that in melt spinning of the mCOC, it is necessary to install a heating board of 1.4 meters length and heated up to 180°C to assisting with the spin draw ratio of the mCOC. The elongation rheology of the mCOC was found to be greatly affected by the presence of cyclic olefins. The optimal spinning speed is 1500 m/min. In such a speed, the spin draw ratio of the mCOC is 90, which is higher than the literature value of 10[11], but still far smaller than 200–400 for typical linear polymers. Experimental results suggest that hot drawing, with a drawing ratio of 1.15 and godet temperature of 200°C, can yield yarn with optimal tenacity of 1.4 g/den. Birefringence observations indicate that mCOC yarn, even via melt spinning and hot drawing, does not exhibit any bulk orientation. The result of X-ray diffraction implies that hot drawing can enhance the formation of nano-crystals with an average size of approximately 6.5 nm. This takes place on the short linear olefin chains among the cyclic segments. The degree of crystallization increases slightly as the godet temperature increases.

A flame-retardant copper-clad laminate composite made of (metallocenebased cyclic olefin copolymer/glass)/ cresol-novolak epoxy with low dielectricity

“…Table 2 demonstrates that the tilt displacement can be reduced from approximately 4 mm to zero regardless of the compositions of the laminates as the setting temperature is increased to 120 C. Notably, the effective setting temperature, 120 C, is far from the T g values of the epoxy (227 C) and mCOC fabrics (187 C). Our previous study 14 found that micro crystals of the olefin (PE) block appeared among the cyclic groups inside the mCOC chains. Setting at 120 C under compression can soften and reshape the micro crystallized PE domains of mCOC fabrics, relaxing the residual stress at the glass/mCOC interface of the prepregs inside the composite.…”

“…mCOC fabric mCOC fiber was formed via the melt-spinning process that is described in the authors' previous study. 14 The spinneret that was used in this experiment had 48 holes, each with a diameter of 0.2 mm, to produce the filaments with a yarn fineness of 150 d/48 f. Notably, the stiff surface of the mCOC fiber caused a serious peeling problem, which interrupted the weaving process. Wrapping the as-spun mCOC yarns with a PVA bundle to form a ''PVA/mCOC single cover yarn'' (Figures 1(a) and (b)) was found to be an effective means of making a plain-weaved mCOC fabric.…”

“…[7][8][9][10][11][12] The authors' previous study demonstrates that the mCOC (metallocenebased cyclic olefin copolymer) fiber can be produced by the melt-spinning process with a particular quenching set-up. 13,14 Consequently, the mCOC fiber has become a potential replacement for glass fiber in high-frequency PCBs owing to its low dielectric constant -typically half of that of glass fiber. In this work, mCOC fibers are weaved to make mCOC fabric with the help of PVA (polyvinyl alcohol) fibers as a sheath layer.…”

Physico-chemical ageing of ethylene–norbornene copolymers: a review

“…Studies have also been made in other fields, concerning the formation of COC nanoparticles [35], production of COC/silica nanocomposites foams [36] and the processability of COC yarn by melt spinning [37]. Very recently, a paper has been published by Saadé et al [38], concerning the modification of cyclic olefin copolymer in order to conduct to new electrochromatographic stationary phases.…”

A study of ethylene vinyl alcohol copolymer fiber for the drawing process

“…If the drawing temperature is too low or too high, the mechanical property of fibers is decreased accordingly. [21][22][23] The degree of orientation of fibers can be determined by birefringence, sonic modulus or X-ray diffraction methods where the birefringence method measures the orientation of the segment of molecular chains, the sonic modulus method measures the bulk-orientation of fibers and the X-ray diffraction method measures the orientation of the crystalline region. [24][25][26] In this study, as-spun fibers were fabricated by melt spinning 1 using EVOH raw materials with various ethylene contents (EV-32, EV-38 and EV-44 roughly having 32, 38 and 44 mole% of ethylene composition units, respectively) to search for the optimal drawing temperature.…”