SURFACE OF GELATIN MODIFIED POLY(L-LACTIC ACID)FILM

In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive sites for gelatin immobilization. The functional groups of the PLLAfilms were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by usingenvironmental scanning electron microscopy (ESEM), and the hydrophilicity of modified PLLA films was examined bywater contact angle measurement. Experimental results showed that the gelatin was immobilized with water-solublecarbodiimide (EDC) onto the PLLA film's surfaces, and the gelatin content on the polymer surface was related to carboxylicgroup formed in the controlled hydrolysis process. Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell; and the hydrophilicity of these surfaces after the modification procedure is enhanced.     

STUDY ON PYROLYSIS OF POLYPHENYLSILSESQUIOXANE

X-ray photoelectron spectroscopy and Raman spectroscopy were used to determine the chemical change ofpolyphenylsilsesquioxane (PPSQ) during pyrolysis in flowing nitrogen. Two temperature ranges were found for pyrolysedPPSQ below and above 600℃, respectively. The former is related to the rearrangement of PPSQ backbone and the latterreflects that most of backbone structure of PPSQ might be broken down and unorganized. Carbon formed in carbonization ofPPSQ sample pyrolysed at 900℃ should be sp~3 bonded carbon with crystallite size effects or defects.     

INFLUENCE OF THE SOLVENT SWELLING ON MACROMOLECULAR CHOLESTERIC LIQUID CRYSTALLINE STRUCTURE*

Ethyl-cyanoethyl cellulose [(E-CE)C]/cross-linked polyacrylic acid [PAA] molecular compositeswith cholesteric order were prepared. It was found that the macromolecular cholesteric structure was changedwith the swelling of PAA in the composites. The selective reflection of the cholesteric phase shifted to thelonger wavelength and the X-ray diffraction angle shifted to the high angle direction during swelling, whichsuggested that the cholesteric pitch and the number of the layers of ordered (E-CE)C chains in the cholestericphase were increased.     

阴离子型聚氨酯水分散液与明胶相互作用的研究

将明胶作为皮蛋白的模型化合物与阴离子型聚氨酯水分散液（ＡＰＵ）反应，来探讨聚合物型助剂与皮革在分子水平上的相互作用机理．该文采用紫外 可见光谱、红外光谱研究了混合体系对ｐＨ值的依赖性，明胶／ＡＰＵ配比、极性化合物对体系相互作用的影响．     

A STUDY ON MECHANICAL PROPERTIES OF γ-RAY IRRADIATED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE*

The effect of γ-ray irradiation on the mechanical properties of high densitypolyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The ex-perimental results show that γ-ray irradiation can improve the affinity between HDPE andSTC, and the dispersion of STC in HDPE matrix. Compared with HDPE/STC (80/20)blend, the yield stress and impact strength of irradiated HDPE (10kGy)/STC (80/20) blendare increased from 22.8 MPa and 70J/m to 28.5 MPa and 144J/m. The yield stress andimpact strength of HDPE/irradiated HDPE/STC (48/32/20) are 27.8MPa and 210J/m,respectively.     

STUDY ON MEAN-SQUARE RADIUS OF GYRATION FOR POLYALKYLENEOXIDES

Taking account of the effect of heteroatoms in backbone, this article dealt with themean-square radii of gyration of polyalkyleneoxides by the approach of matrix algebrain accordance with the rotational isomeric state model. Numerical calculation with theparameters available in the literatures indicated that the dependence of on themolecular weight can be expressed by the general formula: = aM~b     

明胶中α组分含量对明胶/羟基磷灰石复合材料力学性能的影响

选用α组分含量分别为20.5%,41%和50%的A、B、C 3种明胶作为原料,采用同时加入法制备了明胶/羟基磷灰石(HAP)复合材料.通过对干态复合物膜拉伸性能的测试和对比,发现,明胶α组分含量的变化对复合材料的弹性模量影响较大,而对拉伸强度和断裂伸长率的影响则相对较小,但总的来说,三者均随α组分含量的增加而增大.其中,α组分含量最高的复合物C的拉伸强度为86.40 MPa,弹性模量为2682.35 MPa,断裂伸长率为8.65%.另外,对复合物C基本性质的表征结果表明,该材料具有类似于自然骨的组成和结构性质,因此有望成为一种具有优异力学性能的骨替代材料.     

甲壳胺-明胶共混物的研究

甲壳胺 明胶共混物的研究莫秀梅（华东理工大学高分子材料系上海２００２３７）关键词甲壳素，明胶，共混物，红外光谱甲壳胺是甲壳素的脱乙酰基产物，即将甲壳素Ｃ２上的乙酰基脱去变成氨基，因此在甲壳胺分子侧链上增加了一个活泼氨基，从而易于化学改性或共混改性．...     

IN SITU INTERFEROMETRIC STUDY ON THE GELATION PROCESS OF POLYACRYLIC ACID GELS*

In situ interferometry was used to investigate the gelation process of polyacrylic acid (PAA) gels. The basicprinciple of the in situ interferometry technique is illustrated. It can give sufficient information for non-destructive andsuccessful investigation of the whole gelation process. The effect of initiator concentration on the gelation process wasstudied. The polymerization rate of AA increases with increasing initiator concentration. The error arising from the thermaleffect in the gelation process can be neglected.     

STUDY ON 1-HEXENE POLYMERIZATION BASED ON ZIEGLER-NATTA CATALYSTS WITH DOPED SUPPORT

A series of Ti/Mg supported catalysts are prepared by using ball-milled mixtures of MgCl2-ethanol adducts and NaCl as supports, and 1-hexene polymerizations catalyzed by the novel catalysts are studied. It is found that the molecular weight distribution of poly(1-hexene) becomes apparently narrower when catalysts with doped supports are used, indicating that changing the structure of the support is an effective way to regulate the active center distribution of heterogeneous Ziegler-Natta catalyst.     

电感耦合等离子体发射光谱法测定明胶中痕量元素

应用电感耦合等离子体发射光谱技术，建立了定量测定明胶中铁等13种微量元素的方法。采用湿法消解对明胶样品进行了前处理。讨论了ICP-AES同时测定明胶中13种微量元素时，利用功能强大的化学工作站对物理干扰和光谱干扰、背景进行消除。结果表明，此法准确、快速，检出限低，相对标准偏差及回收率均较好。被测元素工作曲线的线性相关系数≥0.9995。     

SCIENTIFIC PRINCIPLES FOR MODIFICATION OF WATER-SOLUBLE POLYMERS. FORMATION OF MACROMOLECULAR COMPLEXES

The study of nanosecond dynamics of macromolecules with the lumines-cent methods make it possible to investigate the formation and functioning of polymericcomplexes, polymeric conjugates and macromolecular metal complexes, which are widelyused for solving many practical tasks. The nanosecond dynamics of macromolecules are ahighly sensitive indicator of interpolymer complexes (IPC) formation. It enables us to solvethe problems of studying IPC formation and stability and to investigate the interpolymerreactions of exchange and substitution. The investigation of changes in the rotational mo-bility of globular protein molecules as a whole makes it possible to determine the complexcomposition and its stability, and to control the course of polymer-protein conjugate forma-tion reaction. The nanosecond dynamics of polymers interacting with surfacants' ions (S)are the sensitive indicator of the S-polymer complex formation. A method for determin-ing the equilibrium constants of the S-polymer complex formation was developed on thebasis of the study of polymer chains mobility. It is established that nanosecond dynamicsinfluences the course of chemical reactions in polymer chains. Moreover, the marked effectof the nanosecond dynamics is also revealed in the study of photophysical processes (theformation of excimers and energy migration of electron excitation) in polymers with pho-toactive groups. It was found that the efficiency of both processes increases with increasingthe mobility of side chains, the carriers of photoactive groups.     

STUDIES ON THE POLYMERIZATION OF β-CYCLODEXTRIN WITH EPICHLOROHYDRIN*

Different proportions of β-cydodextrin and epichlorohydrin were used to prepare a group of β-cyclodextrin polymers. The relationship between the reaction extent and the molar ratios of reactants was discussed according to the results of ~1H-NMR, ~(13) C-NMR spectra and elemental analysis. Especially, high resolution ~1H-NMR spectra were usd for studying the reaction active sites and the extent of reaction. The solubility of oil soluble drugs in water was largely improved in the presence of water-soluble β-cyclodextrin polymer.     

MICROMOLDING ON CURVED SURFACES WITH THERMOPLASTICS

Microstructures were produced on curved surfaces and micro-protrusions by using direct micromolding with fourthermoplastic polymers. This method is simpler and more convenient than micromolding with liquid prepolymer or using theμTM method. By repeated molding, crossed structures were produced with a stamp prepared only with lines. The processingvariables including the softening temperature of the polymers and heating time were discussed. The result shows that theoptimal molding temperature is preferably slightly higher than the melting temperature of the thermoplastic polymers, atwhich polymers are in the critical states of being melted. This method can be applied to many polymers except those with high softening temperatures or high rate of shrinkage upon temperature change.     

STUDY ON SOLID STATE POLYCONDENSATION OF POLYETHYLENE TEREPHTHALATE COPOLYMERS

The kinetic data of solid state polycondensation of PET and its copolymers are determined.It is shown that the reaction rate of copolycondensation is higher than that of PET polyconden-sation, and increases with the comonomers content. But the reaction rate of copolycondensationin melt state of this kind of copolymers is lower than that of PET. It is considered that the chemi-cal reactivity of comonomer is the main factor which affect the polycondensation in melt state,whereas the aggregative structure of the polymer is the main factor in solid state. The crystallinity and crystallite size of the copolymers have been measured by X-ray method.     

STUDY ON A HYDROPHOBIC-HYDROPHILIC GRADIENT ROD

INTRODUCTIONGradient materials constitute a special case of various materials. The concentration of one of the components ofthe material, being chemically and/or physically different from other components, is allowed to change as afunction of its position in the sample, producing a predetermined gradient profile. The gradient material can be inany shape — i.e., linear, sigmoid, parabolic, flat or rod. Generally, this kind of material should have gradientsalong one direction in their stru…     

STUDIES ON THE KINETICS OF PROPYLENE POLYMERIZATION WITH THE COMPLEXTYPE TiCl_3 CATALYST

The active center concentration C_p, the rate constant k_p, and the activation energy of chain propagation E_p in the polymerization of propylene with complex-type TiCl_3-(C_2H_5)_2AlCl catalyst system were studied. The Mn was corrected by (?) value determined by GPC. The values thus obtained for C_p, k_p, and E_p at 50℃were 3.01 mol/mol Ti, 6.27 1/mol·sec, and 5.10 Kcal/mol respectively.The kinetic parameters were compared with those obtained from conventional TiCl_3·AlCl_2 catalyst, showing that the higher activity of the complex-type catalyst over the conventional catalyst is not only due to the higher C_p of the former, but to a greater extent due to the increase of the k_p value.     

ADSORPTION OF PROTEIN ON NANOPARTICLES

The adsorption of protein on nanoparticles was studied by using dynamic light scattering tomeasure the hydrodynamic size of both pure protein and nanoparticles adsorbed with differentamounts of protein. The thickness of the adsorbed protein layer increases as proteinconcentration, but decreases as the initial size of nanoparticles. After properly scaling thethickness with the initial diameter, we are able to fit all experimental data with a single mastercurve. Our experimental results suggest that the adsorbed proteins form a monolayer on thenanoparticle surface and the adsorbed protein molecules are attached to the particle surface atmany points through a possible hydrogen-bonding. Our results also indicate that as proteinconcentration increases, the overall shape of the adsorbed protein molecule continuously changesfrom a flat layer on the particle surface to a stretched coil extended into water. During thechange, the hydrodynamic volume of the adsorbed protein increases linearly with proteinconcentration.     

STUDY ON SEGMENTED POLYURETHANE WITH MIXED SOFT SEGMENTS OF POLYCHLOROMETHYL METHYL SILOXANE AND POLYTETRAMETHYLENE OXIDE

Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and poly-tetramethylene oxide in different weight fractions were synthesized. The phase separation ofsamples was studied using DSC and dynamic mechanical property analysis. The results showedthat the introduction of chloromethyl group into polysiloxane increased its polarity and henceimproved the miscibilities with polytetramethylene oxide and polyurethane hard segment.Particularly, in the case of N-methyldiethanolamine extended materials, the surface and tensileproperties of these samples can be adjusted by various ratios of two soft segments.     

A NEURAL NETWORK STUDY ON GLASS TRANSITION TEMPERATURE OF POLYMERS

In this paper, an atificial neural network model is adopted to study the glass transition temperature of polymers. Inour artificial neural networks, the input nodes are the characteristic ratio C_∞, the average molecular weigh M_e betweenentanglement points and the molecular weigh M_(mon) of repeating unit. The output node is the glass transition temperature T_g,and the number of the hidden layer is 6. We found that the artificial neural network simulations are accurate in predicting theoutcome for polymers for which it is not trained. The maximum relative error for predicting of the glass transitiontemperature is 3.47%, and the overall average error is only 2.27%. Artificial neural networks may provide some new ideas toinvestigate other properties of the polymers.