最新刊期
卷 ， 期 3 ， 1980
- 摘要：Based on the X-ray diffraction data of amorphous polypropylene specimen, the authors have proposed an improved expression describing the X-ray scattering by amorphous component.The improved computational multipeak resolution procedure has been successfully applied to the study of the structure of various polypropylene fibers.
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发布时间：2021-03-19 - 摘要：A porous silica microsphere packing, NWG, having particle sizes of 3-5 μ and 5-10 ft for high-performance GPC was prepared by a refined method. The molecular weight permeation limit of this packing for polystyrene was found to be 4×104 to 7×106. Its separation capacity is not less than 0.6, and the column efficiency is higher than 1×104 plates/m. Experimental results showed that it is possible to separate 100-3×106 MW samples in 10 minutes on a 30 cm×10 mm column. The behavoir of NWG under different flow velocities is in accord with the expectation of the material balance equation theory of GPC.
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发布时间：2021-03-19 - 摘要：The relationships between crack propagation resistant factor K10，the compositions of PMMA organic glasses，and cross-head rates of clamps were determined by conduc-ting tensile testing of centrical notched samples．It was observed by experiments that influence of plastieizers and cross-linlring agents on crack propagation resistant pro-perties of organic glasses may be explained by molecular motion which influences plastic yielding process near crack tip．The two different crack propagation processes of organic glasses，i.e．slow and fast crack propagation processes，were studied．By studying the morphology，the refractive index，the thickness of fracture surface layers and the relationships of K1c values with cross-head rates of clamps，we are convinced that a "tearing cloth" fracture model for slow crack propagation and secondary fracture model for fast crack propagation of organic glasses may be used to explain all phenomenons which were observed in this experiments．It is interested to observe that every secondary fracture shower on banded structure surface is corresponding to one parabola．
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发布时间：2021-03-19 - 摘要：Polyphenylquinoxaline (PPQ) was usually synthesized from tetraamine and te-traketone. We found that the oxidizing agent--selenium oxide (SeO2) commonlyused in the synthesis of tetraketone was not satisfactory. In this work we replaced selenium oxide by dimethyl sulfoxide (DMSO), resulting in a simplified procedure, lower cost and high purity. In order to facilitate the coating process, stable solutions of relatively high molecular weight PPQ were prepared by changing the stoichio-metry with 1-2% excess of tetraketone. All properties of these polymers were de-termined on their films and varnished wires.It was shown that the PPQ can be used as a good water resistant,chemical resistant and/or oil resistant materials.
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发布时间：2021-03-19 - 摘要：By using bicyclo [2.2.1] hept-5-ene-2，3-diearboxylie acid ethyl ester，benzonphe-nonetetracarboxylic acid diethyl ester and methylene dianiline as monomers and ethanol as solvent“PMR”polyimide was synthesized．This type of pvlyimide is suitable for preparation of composites．The results of isothermal aging at 300℃ indicated that the glass cloth reinforced plastic of this polyimide can be used in the range of 250一300℃ for long period．It has been verified that the ester．ammonium salt was formed in the resin solution as soon as the monomers were mixed．The separation of the resin solution in ethanol into two layers was overcome．The reaction mechanism of“PMR”polyimide，such as amidation，imidation and crosslinking．were studied．
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发布时间：2021-03-19 - 摘要：The morphology of polyethylene spherulite in two deformation steps before and after annealing was investigated under the polarizing microscope. It was found that the first deformation step is reversible while the second one is irreversible. Furthermore, it is revealed that the fracture of fibre results from the longitudinal sliding displacement of fibrils or microfibrils.
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发布时间：2021-03-19 - 摘要：Eight linear conjugated compounds have been synthesized by reacting terephthal-dehyde and glyoxal with aromatic diamines．The UV-Vis．spectra of the model com-pounds and their corresponding polymers revealed that the absorption bands shift toward the long-wave region as the degree of conjugation increases．It was shown from the structure of the condensation product of glyoxal and p-phenylene diamine that the aromatization occurs after heat-treatment．but in case of condensation of terephthaldhyde with p-phenylene diamine further polycondensation instead of aromatization took place during the heat-treatment below 350℃．Electric properties of the polymers depend not only on the degree of conjugation in molecules but also the structure between molecules．
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发布时间：2021-03-19 - 摘要：A GPC method for the determination of residual monomers in poly-N-vinylcarba-zole is described. The precision of the determination, expressed as average relative standard deviation, is about±2%. The minimum detectable quantity of monomer in poly-N-vinylcarbazole is 0.03%. The effects of gel permeation limit, purity of solvent, and different kinds of detectors on the experimental results were discussed.
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发布时间：2021-03-19 - 摘要：Several new γ-alkoxy-β-hydroxypropyl acrylates have been synthesized and polymerized.Both poly(MHPA) and poly(MHPMA) hydrogels possess equilibrium water content values nearly 7 and 3 times higher than that of the poly(HEMA) hydrogel.These rather high equilibrium water content values may be attributed to the presence of the hydrophilic γ-methoxy-β-hydroxypropyl side group on the acrylic backbone.
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发布时间：2021-03-19 - 摘要：Benson-Buss's group additivity method for estimating thermodynamical parameters for low molecular compounds has been extended to polymers. Both the heat and entropy of polymerization for head-to-tail or tail-to-head structure may be expressed as follows,△Hgg = △Hf0 (polymer structure unit) - △Hf0 (monomer), △Sgg = S0 (polymer structure unit) - S0 (monomer).In general, the empirical expressions mentioned above have several advantages, they are simple, intuitive, having definite physical meaning and do not need of in-troducing any other empirical parameter. The heat andentropy of polymerization for 28 typical polymers have been estimated.
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发布时间：2021-03-19 - 摘要：The inhibition effects of 2,2, 6, 6-tetramethyl-4-oxo-piperidine-l-oxyl (TMPO) on radical polymerization of methyl methacrylate, styrene and isoprene under the initiation of benzoyl perooxide or α, α'-azodiisobutyronitrile have been studied. The experimental results showed that the inhibition effect is predominant when the concentration of TMPO is approximately equal to 0.1% of that of monomers. This effect becomes more prominent when TMPO is incorporated with quinones, such as 1,4-ben-zoquinone, 1, 4-naphthoquinone,9,10-phenanthrenequinone and chloranil.
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发布时间：2021-03-19
Research Article
- 摘要：The texture-structure and defect of the wet-spun acrylic fiber have been investigated by scanning electron microscopy (SEM). The existence of a multiple fibril-pore type of structure has been established in highly stretched wet-spun acrylic fiber. The fibrils are well oriented in the direction of the fiber axis, and the pores are elongated in the same direction. The texture of the broken surface of this acrylic fiber shows fracture with axial splitting. This machanism of the fracture involves both separation and rupture of the fibrils. Morphological characteristics of the defect in acrylic fiber have been analyzed.
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发布时间：2021-03-19 - 摘要：Silicone rubber compounds eonsisting of polyorgano-H-siloxanes，vinyl polysiloxanes，silica filler and ehloroplatinie acid catalyst were cured via addition reaction at room temperature to form silieone rubber．This RTV silicone rubber (cured for five days at 25—30℃) has the following properties：hardness shore A，12—17，tensile strength 45 kg／em2，tear strength 9 kg／cm elongation 650％，adhesion shear strength (on Al) 45 kg/cm2．The adhesion strength increases with time and may attain to 56 kg／cm2．After aging at 200℃ for 24 hours， it still remains at 65kg／cm2 without any change of other mechanical properties．The elastic RTV silicone adhesive can be used as sealing．encapsulating and bon-ding material for mechanical，electronic，aixeraft，aero-spaee and solar energy devices．
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发布时间：2021-03-19
Research Bulletin
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