摘要:

AbstractThe miscibility of poly (styrene‐co‐4‐vinylphenyldimethylsilanol) (ST‐VPDMS) and poly (n‐butyl methacrylate) (PBMA) blends has been investigated by means of DSC and FT‐IR spectroscopy. It was found that miscible blends were formed only for the copolymers containing 9–34 mol % 4‐vinylphenyldimethylsilanol (VPDMS). The glass transition behavior of the miscible blends was analyzed by recently proposed equations in terms of the physical meaning of the fitting parameters. The results of FT‐IR study were found to be fully consistent with the observation of the miscibility window obtained from glass transition temperature measurements. Quantitative information concerning intermolecular hydrogen bond interaction in the carbonyl stretching vibration region of the miscible blends was obtained by curve‐fitting method. © 1994

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321401

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe preparation of oligodihexanoylchitin(3)having hydroxy groups at the both ends was carried out by an acid hydrolysis of a parent dihexanoylchitin in a mixed solution of acetic acid and conc. hydrochloric acid (11 : 1 in volume) at a room temperature. After 13–21 h, the products were isolated and their molecular weights were calculated as 7400–1100 by GPC analyses. The structure of the product3was determined by1H and13C‐NMR and IR spectra. The IR spectra of the products yielded for longer hydrolysis times than 30 h, however, indicated the occurrence of the dehexanoylation. The block copolymerization of3with poly (propylene glycol) (PPG) using 4,4'‐methylenedi (phenyl isocyanate) (MDI) as a coupling reagent gave the block copolymer6. The molecular weight of6as obrained by GPC was 52,000. © 1994 John Wiley&S

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321402

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractCrosslinked poly (methyl methacrylate) and poly (carbonate‐urethane) as well as full interpenetrating network on their base (IPN) were characterized by precise heat capacity measurements in the temperature interval 1.2–150 K. As judged by the positive sign of the excess Gibbs free energy in the whole temperature interval above 30 K, the apparently single‐phase state of IPN is thermodynamically unstable; however, its kinetic stability is ensured by permanent chamical crosslinks prohibiting the incipient phase separation. © 1994 John Wiley&Son

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321403

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

Abstract2,2'‐Dimethyl‐4,4'‐diamino‐biphenyl was used to prepare a lyotropic amine‐terminated polyamide (PBTA) prepolymer with terephthaloyl dichloride, and an amide oligomer with reactive endcaps of maleimide, respectively. The former was employed in an attempt to increase the solubility of PA/PI block copolymers, and the latter to produce a three‐dimensional (isotropic) reinforced molecular composite through the technology of a semiinterpenetrating polymer network (semi‐IPN). PBTA prepolymer was copolymerized with an amine‐terminated polyimide via a coupling reaction using terephthaloyl dichloride. The resultant block copolymers were characterized by IR, NMR, ηinhand GPC to confirm that the copolymerization reaction was precisely accomplished, as well as to determine their composition and molecular weight. Thermal analysis and lyotropic behavior were also studied for these copolymers. Rigid‐rod amide oligomer was crosslinked in the presence of another flexible polyimide. Five sets of semi‐IPN films were prepared under varying compositions. The curing conditions were investigated by DSC; in addition, the cured semi‐IPNs exhibited a single phase (1Tg) according to examination by an instrument for thermally stimulated current (TSC). No large‐scale phase separation was observed in SEM images of the fractured surfaces. ©

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321404

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractVarious aliphatic polyesters such as poly (ethyleneadipate), poly (tetramethylene adipate), poly (caprolactone), and poly (carbonate) were condensed with 4,4'‐azobis‐4‐cyanopentanoyl chloride to prepare macro‐azo‐initiators. Their thermal properties, observed by differential scanning calorimetry, showed similar decomposition behavior to each other. Block copolymers containing each of these polyesters as a block segment combined with polystyrene or poly (methylmethacrylate) have been derived by the polymerization of monomers initiated with these macro‐azo‐initiators. © 1994 John W

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321405

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA dicarboxylic acid (I) was prepared from the condensation of 9,9‐bis[4‐(4‐aminophenoxy) phenyl] fluorene and trimellitic anhydride. A new family of poly(amide‐imide)s having inherent viscosities of 0.75‐1.04 dL/g was prepared by the triphenyl phosphite activated polycondensation from the diimide‐diacidIwith various aromatic diamines in a medium consisting ofN‐methyl‐2‐pyrrolidone (NMP), pyridine, and calcium chloride. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP andN,N‐dimethylacetamide. All the soluble poly(amide‐imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 262–325°C and the 10% weight loss temperatures were above 525°C in air. ©

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321406

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractNew strategies for the synthesis of perfectly alternating segmented polyimide‐polydimethyl siloxane copolymers were developed by utilizing a transimidization method. Imide oligomers endcapped with 2‐aminopyrimidine were reacted with aminopropyl terminated (dimethyl siloxane) oligomers to afford perfectly alternating segmented imide siloxane copolymers. The polymerization was conducted in solvents such as chlorobenzene and chlorofrom. High molecular weight, fully imidized perfectly alternating segmented imide siloxane copolymers were obtained within 2 h at temperatures of 60‐110°C. The mechanism of the reaction was further elucidated via model compounds and NMR characterization. The block copolymers exhibited twoTgs due to the microphase separation of the polyimide and polysiloxane phases. TheTgof the polyimide phase was a function of the length of the polyimide block. However, partial phase mixing was also evident from the DSC results on the imide siloxane copolymers prepared with low molecular weight polyimide segments. Thermooxidative stability and tensile properties of the perfectly alternating segmented imide siloxane copolymers were found to be principally dependent on the amount of poly (dimethyl siloxane) incorporated in the copolymer and did not correlate with the poly (dimethyl siloxane) or polyimide block lengths. The stress‐strain behavior of both solvent cast films or molded films is also reported. © 1994 John Wiley&

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321407

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractPolystyrene‐based crosslinked cationic ionomers containing ammonium or phosphonium chlorides (AxRCI and PxBuCI) were reacted with decyl methanesulfonate. The kinetic data were correlated with the swelling behavior of the ionomers and the solution viscosity of the corresponding linear ionomers. The reactivity of the ionomers was independent of the particle size of the ionomer beads, indicating no diffusion control of the reaction. The solvent and the ion content of the ionomers greatly affect the reactivity. In nonpolar solvents with a low acceptor number,AN, such as toluene, the aggregation of ionic groups with an increasing ion content reduces the reactivity. A solvent with a high value ofAN, such as chloroform, led a very low reactivity independent of the ion content. Aprotic polar solvent, such as acetonitrila, promoted the dissociation of the ionic groups and furnished a relatively high reactivity independent of the ion content. Several catalytic substitution reactions were carried out under liquid‐solid‐solid triphase conditions. The kinetic results were accounted for in terms of slow nucleophile transport and fast chemical reaction within the ionomer particles. © 1994 John Wiley&Son

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321408

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA new chain transfer agent, ethyl 2‐[1‐(1‐n‐butoxyethylperoxy) ethyl] propenoate (EBEPEP) was used in the free radical polymerization of methyl methacrylate (MMA), styrene (St), and butyl acrylate (BA) to produce end‐functional polymers by a radical addition–substitution–fragmentation mechanism. The chain transfer constants (Ctr) for EBEPEP in the three monomers polymerization at 60°C were determined from measurements of the degrees of polymerization. TheCtrwere determined to be 0.086, 0.91, and 0.63 in MMA, St, and BA, respectively. EBEPEP behaves nearly as an “azeotropic” transfer agent for styrene at 60°C. The activation energy,Eatr, for the chain transfer reaction of EBEPEP with PMMA radicals was determined to be 29.5 kJ/mol. Thermal stability of peroxyketal EBEPEP in the polymerization medium was estimated from the DSC measurements of the activation energy,Eath= 133.5 kJ/mol, and the rate constants,kth, of the thermolysis to various temperature. © 1994

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321409

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractTelechelic (8) and end‐functionalized four‐arm star polymers (9) were synthesized through the coupling reactions of end‐functionalized living poly(isobutyl vinyl ether) (5;DPn∼ 10) with the bi‐and tetrafunctional silyl enol ethers, H4‐nC[CH2OC6H4C(OSiMe3) = CH2]n(3:n = 2;4:n = 4). The precursor polymers5were prepared by living cationic polymerization with functionalized initiators, CH3CH(Cl)OCH2CH2X(6), in conjunction with zinc chloride in methylene chloride at −15°C. The initiators6were obtained by the addition of hydrogen chloride gas to vinyl ethers bearing pendant functional groupsX, including acetoxy [OC(O)CH3], styryl (OCH2C6H4‐p‐CH = CH2), and methacryloyl [OC(O)C(CH3) = CH2]. The coupling reactions with3and4in methylene chloride at −15°C for 24 h afforded the end‐functionalized multiarmed polymers (8and9) in high yield (>91%), where those with styryl or methacryloyl groups are new multifunctional macromonome

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321410

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY