Synthesis and properties of styrene–EPDM–vinyl acetate graft polymer

The styrene–EPDM–vinylacetate (SEV) graft polymer, which linked respectively the styrene (St) unit and vinylacetate the (VAc) unit to the ethylene–propylene–diene terpolymer (EPDM) backbone was synthesized by two‐step graft polymerizations: First the graft polymerization of VAc onto EPDM was carried out, and then St was added successively in the prepolymerized solution and further polymerized for a given period to obtain SEV. The effects of concentration of EPDM and an initiator, mole ratio of VAc to St, polymerization time, temperature, and solvent were examined on the graft polymerizations. The synthesized graft polymers (SEVs) that have different contents of St or VAc were identified by Fourier transform IR spectrum. The highest graft ratio has been obtained by 10 wt % of EPDM, 1.0 mole ratio of VAc to St, and 1.0 wt % of BPO in toluene for 48 h at 70°C. The glass transition temperature of SEV is lower than that of poly(vinyl acetate) (PVAc) and polystyrene (PS). The thermal stability of SEV is higher than that of PVAc, PS, and the acrylonitrile–butadiene–styrene (ABS) resin. The tensile strength of SEV was improved as compared with that of EPDM. The light resistance and weatherability of SEV were better than those of ABS. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2296–2304, 2000     

Fracture mechanics investigation on the PP/EPDM/ionomer ternary blends using j-integral by locus method

The fracture mechanics investigation of the polypropylene (PP)/ethylene–propylene–diene terpolymer (EPDM)/ionomer ternary blends was performed in terms of the J-integral by measuring fracture energy via the locus method. Blends were prepared in a laboratory internal mixer. The composition of PP and EPDM was fixed at a 50/50 ratio by weight. Two kinds of Poly(ethylene-co-methacrylic acid) (EMA) ionomers were used. The J-integral value at crack initiation, Jc, of the PP/EPDM/EMA ionomer ternary blends were affected by the cation types (Na⁺ or Zn²⁺) and contents (5–20 wt %) of the added EMA ionomers. The ternary blend having 5 wt % of Na-neutralized ionomer showed a higher Jc value than that of any other ternary blends. The results were discussed with regard to the fracture topology by a scanning electron microscope (SEM). © 1994 John Wiley & Sons, Inc.     

连续时间模糊随机系统分析：状态空间模型分析

研究了连续时间模糊随机系统理论，给出了连续时间模糊随机系统的态变模糊订值映射的定义，讨论并解决了连续时间模糊随机系统的状态空间模型分析。     

Double melting behavior of cyclic tris(ethylene terephthalate)

Summary Cyclic tris(ethylene terephthalate) (CTET) was separated from oligomeric extract of poly(ethylene terephthalate) by the conventional solvent separation method. The structure of CTET was characterized by differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. It is shown that the double melting behavior of meltcrystallized CTET is attributed to the morphological change created by heat-treatment. The effect of the morphological change on the crystal structure of CTET was also examined.     

Copolymerizations of ethylene with 1–decene over various ansa–metallocene complexes combined with Al( i-Bu) 3/ [CPh 3] [B(C 6F 5) 4] cocatalyst

Copolymerizations of ethylene with 1-decene were carried out with a series of stereospecific metallocene compounds, rac–(EBI)Zr(NMe₂)₂ [ 1, EBI = ethylene–1,2–bis( 1–indenyl)], rac–(EBI)Hf(NMe₂ (2), rac–Me₂Si( 1–C₅H₂–2–Me–4– ^t Bu)₂Zr(NMe₂)₂ (3), ethylidene(cyclopentadienyl)(9-fluorenyl)ZrMe2 [4, Et(Flu)(Cp)ZrMe2] and isopropylidene(cyclopentadienyl)(9–fluorenyl)ZrMe₂ [5, iPr(Flu)(Cp)ZrMe₂], combined with Al(i–Bu)₃/[CPh₃] [B(C₆F₅)₄] cocatalyst. All catalyst systems showed very high copolymerization rates and the 1–decene reactivity decreased in the order of 2 > 5 > 1 4 > 3. The reactivity product of ethylene and 1–decene (r _E x r _D) was below 1 except 3 catalyst, corresponding to random copolymer structures with an alternating character. The melting point (T_m), crystallinity (X_C), intrinsic viscosity ([] and density of the 1–decene/ethylene copolymers decreased markedly with an increase in the 1–decene content, regardless of the type of catalytic system.     

Syntheses and biological activities of polymers containing methacryloyl‐2‐oxy‐1,2,3‐propanetricarboxylic acid or 5‐fluorouracil

A series of novel copolymers, poly(methacryloyl‐2‐oxy‐1,2,3‐propanetricarboxylic acid‐co‐exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalic acid) [poly(MTCA‐co‐ETAc)], poly(methacryloyl‐2‐oxy‐1,2,3‐propanetricarboxylic acid‐co‐hydrogenethyl‐exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalate) [poly(MTCA‐co‐HEET)], and poly(methacryloyl‐2‐oxy‐1,2,3‐propanetricarboxylic acid‐co‐α‐ethoxy‐exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthaloyl‐5‐fluorouracil) [poly(MTCA‐co‐EETFU)], were prepared from corresponding monomers by photopolymerizations at 25°C for 48 h. The polymers were identified by FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopies. The number‐average molecular weights of the fractionated polymers determined by GPC were in the range from 9400 to 14,900 and polydispersity indices were 1.2–1.4. The in vitro IC₅₀ values of polymers against mouse mammary carcinoma (FM3A), mouse leukemia (P388), and human histiocytic lymphoma (U937) as cancer cell lines and mouse liver cells (AC2F) as a normal cell line were much higher compared to that of 5‐fluorouracil (5‐FU). The in vivo antitumor activities of monomers and polymers against mice bearing sarcoma 180 tumor cell line were better than those of 5‐FU. The inhibition of DNA replication and antiangiogenesis activities of MTCA and copolymers were better compared to those of 5‐FU. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 57–64, 2004     

Crystalline and viscoelastic properties of branched polyethylenes synthesized using bidentate nickel (II) catalyst

In this work, five branched polyethylenes with different branching units were synthesized using bidentate nickel (II) catalyst containing -diimine ligands. For comparison, one linear polyethylene was also prepared using tridentate iron (II) catalyst containing -diimine ligand. The crystalline structure of the polyethylenes was investigated using X-ray diffraction (XRD) and polarized optical microscope. The crystalline properties were also measured by differential scanning calorimeter (DSC). Viscoelastic properties of the polyethylenes were investigated using rheometric dynamic analyzer. The DSC and XRD results showed that highly branched polyethylenes exhibit no melting points and no predominating crystalline forms, while the linear polyethylene exhibits clear orthorhombic (110) and (200) reflections on XRD pattern and a clear melting point at 118 °C. The viscoelastic properties of the branched polyethylenes were very complicated due to the combined effect of the molecular weight difference and the degree of chain branching as well as the branching structure.     

Sequestration of carbon dioxide by m-xylylenediamine with forming a crystalline adduct

The reaction of m-xylylenediamine (mXD) with carbon dioxide was examined and its feasibility as a sequestration material of carbon dioxide was discussed. The reaction was monitored by using the FT-IR and gravitational methods, while the crystalline structure of the reaction product was investigated with elemental analysis, powder Xray diffraction, single crystallography, and ¹³C MAS NMR spectroscopy. Even at ambient temperature, mXD reacted with carbon dioxide of low partial pressure in the atmosphere and produced a 1: 1 molar adduct which appeared as a white crystalline material. The hydrogen bonds that formed between the adduct molecules resulted in the formation of a stable crystal. The sequestration capacity of mXD was very great, ～280 mg g _mXD ^?1 below 50 °C. An adsorbent prepared by dispersing mXD on silica was capable of capturing carbon dioxide, but it could be regenerated by evacuating at 25 °C.     

Study on the Accuracy of Injection Molded Plastic Gear with the Assistance of Supercritical Fluid and a Pressurized Mold

Plastic gears are lighter and less noisy compared to steel gears, and they can be easily shaped into diverse forms by the injection molding process. For this reason, plastic gears are widely used in industry. An extensive amount of research has been conducted on gear materials and methods of shaping plastic gears for durability and for broader applications. In this article, the focus is on producing a plastic gear shaping method incorporating the injection molding process.

The most important factor influencing the durability of a plastic gear is its accuracy. Unlike steel gears, the dimensions of plastic gears are subject to considerable change during formation, and this is due to certain conditions during the injection molding process and to the mold structure. The main causes of size variability here are the high viscosity of plastic and the shrinkage ratio of the resin. In our study, a supercritical fluid was used to reduce the viscosity of the plastic, and a pressurized mold was used to control the shrinkage ratio of the resin. Thus, production of an improved, more highly accurate plastic gear was achieved.