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We present a novel approach for the preparation of thermotropic liquid crystalline copolyester (TLCP)/multi-walled carbon nanotubes (MWCNTs) composites via in situ polymerization. A two-stage polycondensation procedure was employed in our process, where carboxylic acid modified MWCNTs were dispersed in acetic anhydride via ultrasonication prior to being charged to a prepolymerization reactor together...
A strong bicyclic guanidine base, 1,5,7-triaza-bicyclo[4.4.0]dec-5-ene (TBD), is photo-generated from its tetraphenylborate salt (TBD·HBPh 4 ) and can effectively catalyze the transesterification reaction between the ester and hydroxy groups in polymers. Accordingly, with TBD·HBPh 4 as a photobase generator, a water-soluble polymer blend, namely poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl...
A small amount (1 wt%) of organoclay-modified thermotropic liquid crystalline polymer (TLCP) acting as a viscosity reduction agent in high molecular mass polyethylene (HMMPE) was characterized and compared with purified TLCP (1 wt%) in HMMPE at 190°C and 230°C, respectively, where the TLCP displayed nematic and nematic-isotropic biphase structures. In the TLCP/PE blend at 190°C and 230°C, dramatic...
The co-aggregation process of a diblock copolymer poly(ethylene oxide)-block-polybutadiene (PEO-b-PB) and a homopolymer poly(acrylic acid) (PAA) in solutions was studied. The number-average molecular weights of both the PEO and PB blocks are 5100g/mol; the weight-average molecular weight of PAA is ∼2000g/mol. The co-aggregation was induced by adding a PB selective solvent (i.e., alkane or cycloalkane)...
This paper reports the use of multiwalled carbon nanotubes (MWCNT) to reinforce and toughen gel-spun ultra high molecular weight polyethylene (UHMWPE) fibers. By adding 5wt% MWCNT, ultra strong fibers with tensile strengths of 4.2GPa and strain at break of ∼5% can be produced. In comparison with the pure UHMWPE fiber at the same draw ratios, these values represent increases of 18.8% in tensile strength...
Shear-induced interactions between high molecular mass polyethylene (HMMPE) melt and a thermotropic liquid crystalline copolyester, HBA/HQ/SA (TLCP) were investigated using large amplitude oscillatory shear and capillary shear. Polarized optical microscopy (POM) observations show that the mono-domain nematic TLCP droplets embedded inside a HMMPE melt may be readily elongated using large amplitude...
Polymers containing the pendant propargyl groups can be effectively crosslinked upon UV irradiation in the presence of a small amount of W(CO) 6 . The alkyne–tungsten carbonyl complex was formed initially as evident by IR spectroscopy, which was involved in the subsequent crosslinking reaction. Analyses by UV, IR, and 13 C NMR CP/MAS spectroscopic methods confirmed the polymer crosslinking...
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