Copolymers of methacryl-dicyclohexylurea (MA-DCU) with ethylene glycol dimethacrylate (EDMA) at monomer-to-monomer ratios in the feed: 0.3/0.7, 0.5/0.5, 0.7/0.3, 0.8/0.2 were prepared in butanone in ...the presence of 2% of dibenzoyl peroxide at 70°C for 48 hr. Copolymers, regardless of the ratio of comonomers in the feed, decompose thermally at 200-250°C under the separation of cyclohexylisocyanate (C
6
H
11
NCO). Residues after the removal of C
6
H
11
NCO are thermally stable nanoporous crosslinked copolymers of methacryl-cyclohexylamide (MA-CHA) with EDMA, which decompose by a one-step mechanism between 300°C and 480°C.
Copolymers of methacryl-N,N′-diisopropylurea (MA-DiPrU) with ethylene glycol dimethacrylate (EDMA) at monomer-to-monomer ratios in the feed: 0.3/0.7; 0.5/0.5; 0.7/0.3; 0.8/0.2 were prepared in ...butanone in the presence of 2% of dibenzoyl peroxide (Bz
2
O
2
) at 70°C for 48 hr. Copolymers regardless of the ratio of comonomers in the feed decompose thermally at 200-250°C under the separation of isopropylisocyanate (iPrNCO). Residues after the removal of iPrNCO are thermally stable nanoporous crosslinked copolymers of methacryl-isopropylamide (MA-iPrA) with EDMA which decompose by a one-step mechanism between 280°C and 450°C. Nonporous model copolymers poly(MA-iPrA-co-EDMA) of similar composition, prepared by copolymerization of MA-iPrA with EDMA, also decomposed by a one-step mechanism as shown by TGA measurements.
Crosslinked unswellable copolymers of acryl-dicyclohexylurea (A-DCU) with ethylene glycol dimethacrylate (EDMA) at monomer-to-monomer ratios in the feed: 0.3/0.7; 0.5/0.5; 0.7/0.3; 0.8/0.2 were ...prepared by free radical copolymerization in butanone in the presence of 1% of benzoyl peroxide. The reaction was performed up to high conversion yielding 99-100% of copolymer. Copolymers regardless of the ratio of comonomers in the feed decompose thermally by a two-step mechanism under the separation of almost quantitative yield of cyclohexylisocyanate (C
6
H
11
NCO). Residues after the removal of C
6
H
11
NCO are thermally stable nanoporous crosslinked copolymers of acryl-cyclohexylamide (A-CHA) with EDMA which decompose by a one-step mechanism between 300 and 450°C. In an attempt to compare the thermal properties of nanoporous poly(A-CHA-co-EDMA) with a nonporous model compound prepared by copolymerization of A-CHA with EDMA it was found that both compounds have almost the same thermal stability as proved by thermogravimetric analysis.
Miscibility and phase behaviour in copolymer blends of partially phenylsulphonylated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) with poly(
o-fluorostyrene-co-
p(
o)-chlorostyrene) have been ...studied by differential scanning calorimetry at temperatures up to 573 K. It was found that miscibility depends on the copolymer compositions and the degree of sulphonylation of the SPPO copolymers and on temperature. The width of the miscibility window in the blends containing copolymers with various p-chlorostyrene (pClSt) content and SPPO is much wider than in the corresponding blends containing copolymers with
o-chlorostyrene (oCISt) and SPPO. It was also found that sulphonylated segments of SPPO copolymers enhanced miscibility in comparison with blends with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). A qualitative account of these results was obtained by using the segmental interaction parameters according to the mean-field theory of phase behaviour.
This paper presents an attractive feature of the distribution function, which uses a relatively simple expression for approximating probability density. The Pearson-type I distribution function is ...used to represent the molar mass distribution (MMD) function for polymers for which the number average (M̄ n ), mass average (M̄ w ), z-average (M̄ z ), and (z+1)-average (M̄ z +1) values are available. In continuation, the Pearson-type I distribution is applied as the model MMD function in which model parameters (M̄ n , M̄ w , M̄ z , and M̄ z +1) are fitted from experimentally determined MMD. As the result, different molar mass averages are estimated with satisfactory agreement with experimental data.
Copolymerization of N-acryl-N,N′-dicyclohexylurea with ethylene glycol dimethacrylate or divinyl benzene in the presence of dibenzoyl peroxide as initiator gave corresponding crosslinked copolymers. ...Both copolymers thermally decompose by two-step mechanism. The first step separates cyclohexylisocyanate, thus forming the thermostable residue, which contains molecular imprints of cyclohexylisocyanates.
Ovo je prvi objavljeni dokument IUPAC-ove Komisije za nomenklaturu makromolekula koji obraðuje specifično područje kapljevitih kristala. Zbog opseÞnosti je pripremljen u suradnji s Međunarodnom ...udrugom za kapljevite kristale.
Dokumentom je definirano pojmovlje koje se odnosi na niskomolekulske kapljevite kristale i kapljevite kristalne polimere.
Obuhvaća temeljne definicije pojmova koji su uvrijeÞeni u području kapljevitih kristala i polimernoj znanosti. Pojmovi su podijeljeni u pet poglavlja koja obraðuju: opæe definicije stanja kapljevitih kristala i mezomorfna stanja, vrste mezofaza, optièku teksturu i nepravilnosti kapljevitih kristala, fizikalne karakteristike (ukljuèujuæi elektro-optička i magnetno-optička svojstva), i na kraju kapljevite kristalne
polimere. Odabrani se pojmovi najčešće rabe pri standardnim strukturnim, termièkim i elektro-optičkim karakterizacijama
kapljevitih kristalnih materijala.
PDF