最新刊期
卷 ， 期 5 ， 2001
- 摘要：Monodispersed polystyrene latexes (100～500 nm) were prepared using seed emulsion polymerization．Hard and ordered polystyrene colloidal crystals were obtained by ambient drying the monodispersed polystyrene dispersions．Polystyrene colloidal crystals were chemically modified by controlled sulfonation with sulfuric acid to derive a novel macro-ordered hydrogels including ordered hydrogels and core／shell hydrogels,in which sulfuric acid and sulfone groups are responsible for the bydrophilic and crosslinking performances,respectively．The chemical structure and morphologies of the hydrogels were characterized by FT-IR．It is shown that at a given concentration of sulfuric acid,the structural features of the samples are controlled by sulfonation time and temperature．The modification starts from the outer layer of polystyrene spheres of the colloidal crystals and increases both in reaction rate and sulfone group amount with temperature．A preliminary mechanism of the sulfonation process to prepare the ordered structures was proposed．
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发布时间：2021-03-19
Rapid Communications
- 摘要：The non-isothermal crystallization kinetics of reactive blends of poly(ethylene terephthalate) (PET)／copoly(oxybenzoate-p-terephthalate) at molar ratio 60／40 (LCP) (70／30 by weight) with addition of bis(2-oxazoline)(BOZ) was studied by using differential scanning calorimetry (DSC)．PET and LCP were blended at 280℃ with 1.5 wt％ BOZ in a twin extruder for 5 min or 10 min and then put into ice water bath,respectively．The DSC results show that the Avrami exponent of the PET/LCP reactive blends is in a range of 3.0 to 4.5,which is different from the results of isothermal crystallization of PET/LCP,and the crystallization rate increases with increasing cooling rate．BOZ could promote the transesterification between PET and LCP,resulting in a decrease of the number average sequence length of PET．Therefore,It is demonstrated that,compared to the blends without addition of BOZ,the crystallization rate of the PET in the reactive blends with BOZ decreases,and the crystallinity decreases,too．The peek temperature of crystallization of reactive blends shifts to lower temperature,but the crystallization mechanism of the reactive blends isn’t affected by bis(2-oxazoline) significantly．
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发布时间：2021-03-19 - 摘要：The polysilanes containing chlorine were synthesized by the substitution reactions using polymethylphenylsilane and acetyl chloride,anhydride or ester as reactants in the presence of anhydrous AICl3. The acetyl chloride can lead a nearly complete substitution of phenyl groups with chlorine on silicon atoms．The monobasic anhydrides (acetic and propionic anhydrides) can introduce some acyloxy groups to the polymer,while more phenyl groups were still replaced by Cl．The maleic and o-phthalic anhydrides and CH3COOC2H5 only lead to partly chlorinesubstituted polysilanes．The possible reaction mechanisms were suggested,and the influence factors on the reactions were discussed．The UV and fluorescence characters of these polysilanes were studied as well．
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发布时间：2021-03-19 - 摘要：Aromatic polyamides are well known as one of the most important high-performance polymers due to their excellent thermal stability and other outstanding properties．However,the present commercial polyamides are insoluble and do not melt below their decomposition temperature,which restrict their processing and applications．In the paper,1,2-dihydro-2-(4-aminophenyl)-4-[4-(4-aminophenonxyl) phenyl]-phthalazin-1-one,a novel diamine monomer containing the phthalazinone moiety was synthesized,and a series of polymers based on this monomer were synthesized with the Yamazaki method and studied．The novel diamine and different aromatic diacides were used to synthesize polyamides and co-polyamides which were soluble in polar aprotic solvents such as DMAc,NMP and had inherent viscosity of 1.26～1.51 dL/g(25℃,NMP)．The Tg values of the polyamides were all above 300℃．The properties of polyamides and co-polyamides were studied．The aromatic polyamide films were prepared by the thermal conventional method．The films had tensile strength of 62～89 MPa,elongation to break of 5％-9％ and tensile modulus of 2.2～2.9 GPa．The order of the coefficient of electrical resistance was 1014～1016．Their uhtrafiltration membrane also had good separation properties．The rejection against PEG 12000 could be up to 99.7％ when the water flux was 175 kg／m2·h．
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发布时间：2021-03-19 - 摘要：Polybutadienes were synthesized with η5-pentamethycyclopentadienyltri group titanium[Cp* TiL3,L=chloride,benzyloxy,p-methoxyphenoxy] in the presence of methylaluminoxane (MAO)．The influences of polymerization temperature [Tp],catalyst concentration [Ti] and AlMAO／Ti molar ratio on butadiene polymerization have been studied．The external addition of triisobutylaluminum (TIBA) into the catalyst system gave a great promotion on the catalytic activity and the molecular weight of polybutadienes．The results showed that the best polymerization conditions with Cp* Ti(OBz)3／MAO as the catalytical system were [Ti] =1×10-3 mol／L,Tp=60℃,AlMAO/Ti=400(mol／mol) and AlTIBA/Ti=100．The oxidation states of active titanium centers ln Cp* Ti(OBz)3／MAO catalytic system have been determined by the redox titration method．It seems that the active center of Ti(Ⅲ) is favourable for butadiene polymerization with higher catalytic activity．
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发布时间：2021-03-19 - 摘要：The nonisothermal crystallization kinetics of polypropylene (PP) and polypropylene／organicmontmorillonite (PP／Mont) nanocomposite,which was prepared by melt intercalation,was studied by means of differential scanning calorimetry (DSC)．The modified Avrami theories of Jeziorny,Ozawa and Mo were used to analyze the data of DSC．The result showed that both the Jeziorny and Mo methods could describe this system very well,but the Ozawa analysis failed．The values of Zc and n increased with increasing cooling rate,and the values of Zc and n of PP／Mont nanocomposite were higher than those of PP at the same cooling rate．The value of F(T) increased,and the value of a had no significant change with increasing degree of crystallinity for PP and PP／Mont nanocomposite,respectively. The values of F(T) of PP／Mont nanocomposite were lower than those of PP at the same degree of crystallinity．The value ofa was 1.04,1.40 or so for PP and PP／Mont nanocomposite,respectively．The activation energies have been evaluated by Kissinger method to be 189.37 kJ／mol and 155.69 kJ／mol for the nonisothermal crystallization of PP and PP／Mont nanocomposite,respectively．The addition of organic montmorillonite decreased the activation energy of crystallization of PP,which could be used as nucleating agent during nonisothermal crystallization process of PP．
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发布时间：2021-03-19 - 摘要：The isothermal crystallization kinetics of intercalatively polymerized polypropylene／montmorillonite (PP／MMT) nanocomposites and isotactic polypropylene (PP) was investigated by differential scanning calorimetry (DSC)．The relative crystallization degree of PP/MMT nanocomposites was decreased slightly after introducing montmorillonite．The isothermal crystallization process was described by the Avrami equation with exponent n≈2.4 for pure PP and n≈3.0 for PP／MMT nanocomposites．The half crystallization time (t1/2) of PP／MMT was much shorter than that of pure PP．The σe,interfacial free energy per unit area perpendicular to PP chains,of PP／MMT nanocomposites was calculated by Hoffman theory．The result showed that the σe was decreased with increasing the MMT content．
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发布时间：2021-03-19 - 摘要：Blends of syndiotactic polystyrene (sPS) and isotactic polypropene (iPP) have been prepared using TiCl4/MgCl2/β-diketone-MAO．The influences of Al／Ti ratio and the polymerization temperature on the catalyst activity and the blend composition have been investigated．The catalyst shows a good activity of about 1.5×105 gB／mol Ti·h,and the sPS content can be controlled in the range of 55 wt％～82 wt％．Thermal property and micro- morphology have been studied with differential scanning calorimetry (DSC) and scanning electron microscopy (SEM)．
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发布时间：2021-03-19 - 摘要：The effects of cation and hydration on cation-anion interactions in sulfonated syndiotactic polystyrene (SsPS) ionomers were examined by FTIR spectroscopy．Ionic interactions in SsPS ionomers are reflected in their fTIR spectra directly,affecting the vibrations of the sulfonate anion．It is found that the counterion and hydration have a profound influence on cationanion interactions in the SsPS ionomers containing divalent transition metal cations (such as Mn2+,Zn2+ and Co2+) and alkali metal cations (such as Na+and K+). In the dry materials, the counterion imposes a strong electrostatic field on the sulfate anion that polarizes the S—O dipole and shifts the asymmetric and symmetric vibrations of the sulfonate anion to higher frequencies．While in the hydrated materials,the polarization by the cation weakens and shifts the cooresponding vibrations to lower frequencies. For the unneutralized sulfonated syndiotactic polystyrene,in the hydrated form,the proton of the sulfonic acid is removed from the anion,yielding the sulfonate anion,SO-3．While in the dry form,the FTIR spectra of the sample exhibit characteristic absorbances of the sulfonic acid,—SO3H,group．
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发布时间：2021-03-19 - 摘要：Norbornene polymerization was first carried out by (dienzoylmethanato)2Ti(OPh)2[(dbm)2Ti(OPh)2]／methylaluminoxane (MAO),a type of β-diketonate titanium non-metallocene catalytic system．A mixture of vinyl addition polymer and ring-opening metathesis polymer was obtained．Polymer structure was characterized by FTIR．Influence of polymerization temperature,Al／Ti mole ratio,monomer concentration and solvents on polymerization activity as well as on polymer structure was investigated．Higher activity was achieved at 80℃ with higher Al／Ti mole ratio and monomer concentration as well as 1,2-dichlorobenzene as the solvent instead of toluene．Higher temperature,higher Al／Ti mole ratio,lower monomer concentration have the advantage of forming more ring-opening polymer structure and less addition polymer structure．
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发布时间：2021-03-19 - 摘要：Block copolymerization of acrylamide(AM) and styrene(St) was carried out in a microemulsion system,in which AM aqueous solution was the continue phase and St was the dispersed phase using OP-10 and SDS as surfactants respectively．Water-soluble amphiphilic block copolymer of AM-St was synthesized．The block architecture of the copolymer was characterized by fluorescence probe technology and by measuring the DSC thermograms and the rheological property of the copolymer．The composition of the eopolymer was analyzed by FTIR and UV methods．
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发布时间：2021-03-19 - 摘要：The non-isothermal crystallization and Curie transition behavior of composites consisting of lead zirconate titanate (PZT) particles embedded in a vinylidene fluoride-trifluroethylene (P(VDF-TrFE)70／30)copolymer matrix were investigated using differential scanning calorimetry．The crystallization temperature,crystallization rate and crystallinity of the copolymer matrix was not affected significantly by the inclusion of the PZT particles,while the overall Curie transition enthalpy decreased with increasing the PZT content．The relative amount of enthalpy corresponding to the transition from the paraelectric high-temperature (HT) phase to the ferroelectric cooled (CL) phase also decreased with increasing the PZT content．This suggested that PZT particles might restrain the formation of gauche conformational defects in ferroelectric crystals and make ferroelectric crystals more perfect．
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发布时间：2021-03-19 - 摘要：The thermodynamic properties of a polymer chain with a length of N=100 near an adsorbed surface,modeled by a self-avoiding walk on the simple cubic lattice in addition to both the vertex-plane interaction energy ε1 and the vertex-vertex interaction energy ε2,were calculated by means of the multiple Markov chains method．These two interaction energy terms ε1 and ε2 were related to the vertex-plane interaction parameter α and the vertex-vertex interaction parameter β．The statistical physical quantities obtained by Mont Carlo simulations include the free energy FN(α,β),the heat capacities а2FN(α,β)／а2 α and а2 FN (α,β)／а2 β,the mean number of visits per edge m〉／N．the mean number of contacts per edge〈n〉／N and the mean square z-component Rz2 of the end-to-end distance．It suggests a new method to eonstruct the α-β phase diagram by structure parameters〈m〉／N,〈n〉／N and RZ2,which is very similar to that obtained by the traditional method using peaks of the heat capacity．The α-β phase diagrams indicated that there are four regions of phases,which are desorbed-expanded (DE),adsorbed-expanded (AE),desorbed-compact (DC) and adsorbed-compact (AC)．In both expanded phase and compact phase,there were adsorption transitions as the surface interaction increased．In both desorbed and adsorbed phases,there were collapse transitions as the nearest-neighbor interaction increased．It is also found that there are two triple points in the α-β phase diagram,which represent the coexistance of the three phases AE-AC-DC and AE-DE-DC,respectively．and AE-DE-DC,respectively．
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发布时间：2021-03-19 - 摘要：Atom transfer radical polymerization (ATRP) is a kind of useful method for the realization of living polymerization and syntheses of block copolymers．Polystyrene double-caped with bromine (MWD=1.18),Br-PSt-Br,was synthesized by ATRP method using α,α′-dibromoxylene as initiator and CuBr／2,2′-bipyridine as catalyst and ligand at 110℃．Then using the Br-PSt-Br as difunctional macromolecular initiator,ATRP of p-nitrophenyl methacrylate (NPMA) was realized and ABA type block copolymers,PNPMA-b-PSt-b-PNPMA,were synthesized．After hydrolyzation and acidition,amphiphilic ABA type block copolymers of methyl methacrylic acid and styrene, PMAA-b-PSt-b-PMAA,were prepared．
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发布时间：2021-03-19 - 摘要：The non-equilibrium thermodynamic fluctuation theory was used to predict the gelation time tg and the cure behavior after tg of epoxy／organo-montmorillonite／imidazole intercalated nanocomposites at various temperatures and organo-montmorillonite loadings．The theoretical prediction is in good agreement with the experimental results obtained by dynamic torsional vibration method,and the results show that the addition of organo-montmorillonite reduces the gelation time tg and increases the rate of curing reaction,but has no apparent effect on the apparent activation energy ΔH of the cure reaction after tg．
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发布时间：2021-03-19 - 摘要：The rheology and processability of ultra high molecular weight polystyrene (UHMWPS) synthesized by rare earth catalyst were investigated by using capillary rheometer and Hakke torque rheometer．It was found that the theological behavior of UHMWPS is remarkably characterized by its unstable flow at low critical shear rate and ultrahigh melt viscosity．The unstable flow is attributed to the long relaxation time of the samples resulted from their ultrahigh molecular weight,and a dependence of the critical shear rate on the molecular weight and temperature is presented．Moreover,the low molecular weight and higher temperature are favorable to reduce the melt viscosity,to increase the critical shear rate and to improve the apparent quality of extrudates．The extreme entanglement of polymer chains results in not ouly the ultrahigh melt viscosity,but also the faster dis-entanglement process which leads to a stronger dependence of melt viscosity on shear rate．Furthermore,it is indicated that the processability of UHMWPs is inferior to that of conventional PS because of its higher balance torque determined by Hakke rheometer．
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发布时间：2021-03-19 - 摘要：Inorganic／organic nano-composite materials exhibit enhanced performance due to the nano-size effect of the inorganic phase dispersed in the organic matrix．The conventional way to prepare nano-composite materials is to mix nano-dimensional inorganic particles into a polymer matrix．The inorganic particles,however,are usually nonhomogeneously dispersed because on energy considerations the aggregation of the inorganic particles is favored．In addition,the distinct difference in surface characters between the discontinuous inorganic phase and continuous organic matrix has an adverse effect on the dispersion of the former．The design of a novel inorganic-organic nano-composite structure is thus put forward in this work．By taking advantage of the nano-sized pore diameter and wall thickness,MCM-48 is proposed as the inorganic component of the novel inorganic-organic nano-composite structure．and the nano-composite structure is proposed to be formed through in-situ self-assembly of inorganic silica precursors and organic template．The effects of the conditions including the concentration of alkali solution,pre—hydrolysis step,organic/inorganic molar ratio,pre-assembly time and pre-assembly temperature on the self-assembly have been investigated．The proposed nano-composite structure can be formed with CTABr as the organic template and TEOS as the inorganic precursors．The novel aspect of this nano-composite structure is that the organic phase in the nano-sized pores is isolated by the inorganic phase．The organic template extends along the channels to the openings and is beneficial to the dispersivity of nano-composite particles in both polar and non-polar medium such as water and toluene．The content of the organic template can be varied to optimise the properties of the nano-composites．The inorganic-organic nano-composite particles are expected to be favorable to the interaction bteween the nano-composite structure and a bulk polymer matrix．
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发布时间：2021-03-19 - 摘要：The crystallization behavior of PHBV,poly(β-hydroxybutyrate-co-β-hydrxyvalerate),with nucleating agents under isothermal conditions was investigated．A differential scanning calorimeter was used to monitor the crystallization process from the melt．During isothermal crystallization,the dependence of relative degree of crystallinity on time was described by the Avrami equation．It has been shown that the addition of BN and Talc causes a considerable increase in the overall crystallization rate of PHBV but does not influence the Avrami exponent n,mechanism of nucleation and spherulite growth mode of PHBV．A little of nucleating agent will increase the crystallization rate and decrease the fold surface free energy σe,remarkably．The effect of BN is more significant than that of Talc.
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发布时间：2021-03-19 - 摘要：Hydrogels based on n-alkyl methacrylate esters (n-AMA),acrylic acid and acrylamide cross-linked with 4,4′-di(methacryloylmino)azobenzene were preparared．Swelling behavior of the hydrogels was studied by immersion of slabs of samples in buffered solutions of pH values 2.2～7.4．The process of swelling follows Schott second-order diffusion kinetics．The factors influencing the swelling behavior of the gels include：the degree of cross-linking,the lengths of the n-AMA side chains,pH values et al．
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发布时间：2021-03-19 -
SOLAR PHOTOCATALYTIC POLYMERIZATION OF METHYL METHACRYLATE IN AQUEOUS MEDIUM WITH TiO2/Na2SO3 SYSTEM
摘要：Study on the solar photocatalytic polymerization of methyl methacrylate in aqueous medium of TiO2／Na2SO3 system is given．Reaction system composed of iOH+2,Na2SO3,MMA and deionized water is carried out under constant temperature,solar shining,closed air atmosphere and without shaking．Results show that the initiation period τ is about 2～15 min and mainly depends on the pH value in the system．No initiation period when pH＜6.3．While at the pHzpc of nanometre TiO2(6.3＜pH＜6.7)·SO-3 free radicals produced on the Ti—h+vb—OH initiate the polymerization of MMA and a high yield (95％) with 1.2×106 molecular wight appears at the pH (6.9～7.O) with the decreasing H+ on the Ti—e-cb—OH．However the increasing·OH free radical results in the lower yield at alkaline pH．The apparent rate of polymeriation Rp=k·e-114.800/RT·[MMA]0.94[IA]0.50 [Na2SO3]0.55[TiO2]1.06 in the range of [MMA]=(3.74～10.7)×10-2mol·L-1[Na2SO4]=(1.0～1.56)×10-3mol·L-1 and[TiO2]=(5.0～7.0)×10-5 mol·L-1,similar results were obtained,when using powder TiO2(10～20 nm) to substitute the hydrated TiO2．- 2
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发布时间：2021-03-19 - 摘要：Poly[bis(glycine ethyl ester)phosphazene] was blended with polyanhydride (PSA or PSTP) in various ratios using solvent-mixing technique．The compatibility of these blends was evaluated by DSC and contrast microscopy method．The results showed that PGP was partially compatible with PSTP．In vitro degradation experiment was conducted in distilled water at 37℃．The degradation behavior of PGP／PSTP blends exhibited homogenious．Furthermore,the degradation rate was much faster than that of PGP and could be regulated by adjusting PSTP content due to the catalyze effect of acidic products of PSTP．PGP／PSTP blends could be a series of potential biomaterials for drug controlled release．
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发布时间：2021-03-19 - 摘要：In order to prepare microporous polymer electrolyte used in lithium ion batteries,two types (A-series and B-series) of microporous PAN membranes with high porosity were prepared in vapour atmosphere or coagulating bath from PAN-DMF solutions,respectively．SEM observed the sections of those membranes．It was found that there was a kind of honeycomb structure in the A-series microporous membrane,the size of the pores was inthe order of μm,and their porosity was about 80％．While in the B-series microporous membrane there was an asymmetric structure composed of three layers．The highest ion conductivity of microporous PAN electrolyte of A-series was about 4×10-3 S/cm at room temperature．While the ion conductivity of microporous PAN electrolyte of B-series was relatively low．The effect of influence factors of the microporous membrane on the ion conductivity of microporous PAN electrolytechanges in an order：membrane structure＞porosity＞pore size．
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发布时间：2021-03-19
Research Article
- 摘要：Free-radical solution copolymerization of itaconic acid and acrylonitrile was carried out in DMSO at 58～60℃ using azodiisobutyronitrile as initiator．The resulting polymerization solution was spun to form PAN precursors of carbon fibres．The precursors were treated with NiSO4 aqueous solution at 95℃ on line．The structure and properties of untreated and treated PAN precursors and resultant carbon fibres were characterized by IR,SEM,dynamic viscoelasticity study,stabilization process and so on．It was suggested that carbon fibres developed from modified PAN fibres showed an improvement in tensile strength by about 20％～30％ and Young’s modulus by about 5％～10％.
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发布时间：2021-03-19 - 摘要：As an innovative manufacture technology,there has been a considerable development about the electron beam (EB) curing advanced composites in recent years．Epoxy resin,which has a lot of excellent properties and different molecular structure,is widely used as polymer matrix in composites．Most variety of epoxy resin has been confirmed to possess radiation reactivity and have already become a chief resin matrix used in EB curable composites．The radiation curing feature of bisphenol A epoxy resin was studied in this paper．Firstly,the technique of chemical extraction was used to test the curing degree of epoxy resin and the relationship between radiation dosage and curing degree was analyzed．The experimental data indicate the resin curing degree is increased with the rising of radiation dosage．But after the radiation dosage reached 100 kGy,the increasing extent became very small．The penetration process of electron beam in radiated resin and the structure of cured resin were studied．By analyzing radiation curing area of epoxy resin,it can be seen that EB exhibits intensively scattering in resin system．Around the radiation direction,the curing reaction can be initiated,and the penetration depth of EB will get to a fixed value on account of the gradual attenuation of electron energy．The results of observing the cured areas indicate that EB curing reaction spreads outwards layer upon layer around an active center when EB radiates the epoxy resin．The whole cured area is consisting of many lamellar structures．
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发布时间：2021-03-19 - 摘要：Synthesis of half-metallocene complexes ([O,N]CpTiCl2) containing 8-hydroxy-quinoline ligand is described. The results indicate that [O,N]CpTiCl2 is active for ethylene polymerization at 30℃ and 0.1 mPa with MAO activation,and exhibits much higher activity than CpTiCl3．The results show that when there is an electrondonor substituent next to N,such as a methyl,the activity of [O,N]CpTiCl2 increases greatly；however,if there is an electron-acceptor substituent,such as nitro in the benzene ring,it is inactive．For the [O,N]CpTiCl2／MAO system,the polymerization rate is “up and down” type with increasing the Al／Ti molar ratio．The activity reaches its maximum at molar ratio of Al／Ti=500,which is over 1×105 gPE/molTi·h．The activity decreases as the polymerization time is longer．The polyethylene obtained is characteristic of narrow molecular distribution with molecular weight Mw around 40×104 and molecular weight ratio Mw／Mn=2.8．
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发布时间：2021-03-19 - 摘要：Synthesis and elemental analysis of metallocene analogic complexes (NpCpTiCl2) containing the azole ligand (Np) are described,in which Np is Pr=Pyrolyl (C4H4N)(1)；Id=Indolyl(C8H6N)(2)；Ai=7-Azaindolyl (C7H5N2)(3)；Iz=Indazolyl(C7H5N2)(4)；Bi=Benzimidazolyl(C7H5N2)(5),respectively．It is proved hy the experiments that NpCpTiCl2 is active for ethylene polymerization at 30℃ and 0.1 mPa with MAO activation,and the results show that the activity of 1 and 2 which contain one nitrogen in the azole ring is higher than 4 and 5 which contain two nitrogens,while 3 is inactive．For the NpCpTiCl2／MAO system,the activity is “up and down” type with increase in the Al／Ti molar ratio,and up to the highest when the Al／Ti molar ratio is about 500．The polyethylene obtained is characteristic of narrow distribution with molecular weight Mw around 35×104 and molecular weight ratio Mw/Mn less than 3．
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发布时间：2021-03-19 - 摘要：Polypropylene catalloy was synthesized directly in reactor,which with special chain structure and supper impact strength．For the special synthetic method,its solid phase structure may be different from others. So the solid phase structure of polypropylene catalloy was studied by optical microscope and WAXD. The results indicated that the crystallinity,crystal type of polypropylene are partly changed because of the coexistence of EPR,EP copolymers and PP．There appears a γ-PP crystal when the EP copolymer amount in PP alloy is 17.18％．
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发布时间：2021-03-19 - 摘要：Poly(butylene succinate),(PBS1) was irradiated with Co60-γ radiation at various temperatures．The gel fraction of PBS1 irradiated at molten state (100℃) is higher than that of the samples irradiated at lower temperatures with the same dose．Two-step irradiation (irradiation at room temperature and then irradiation at 100℃) yielded the highest gel content as compared with other treatment conditions．It is due to the network structure formed by preirradiation at room temperature and further irradiation at molten state reduce degradation of PBS1．PBS1 prepared by the two-step irradiation was improved in heat distortion resistance because of its higher gel content．Unirradiated PBS1 sheets broke immediately at 11O℃．On the other hand,for samples (gel fraction 50％) irradiated by asing the two-step method,they did not break even at 130℃ for 200 min．
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发布时间：2021-03-19 - 摘要：The solubility of poly(phenyl glycidyl ether) s (PPGEs) depends on the stereoregularity．Different solvents and temperatures (CDCl3／300 K or TCE-d2／350 K) were used in 13C-NMR characterization of these polymers. It was necessary to investigate first the effect of temperature on the 13C—NMR spectra of PPGEs．It was found that all the 13C-NMR signals of PPGE were shifted to the lower magnetic field with the increase of the temperature．The temperature sensitivity of the 13C-NMR chemical shifts for different carbon atoms was different．The pendent CH2 group was most sensitive to the temperature．The change of the 13C-NMR chemical shift for the pendent CH2 group was mainly caused by the temperature change,and the effects of the solvent kind and the stereoregularity of the polymer were of minor importance．The change of temperature did not make any significant influence on the result of the stereoregularity calculation according to the 13C-NMR spectra for PPGEs．Utilizing the different temperature-sensitivity of 13C-NMR signals for different groups,it is possible to separate the overlapped signals by choosing an appropriate temperature．This method was found especially useful in the 13C-NMR characterization of complex polymer samples．
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发布时间：2021-03-19
Research Bulletin
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