Guangmin Cong

Influence of modified wood fibers on the mechanical properties of wood fiber-reinforced polyethylene

Wood fiber of aspen was used as a reinforced filler in linear low-density polyethylene (LLDPE). To improve the compatibility between the wood fiber and the LLDPE matrix, the wood fiber was treated with titanate coupling agents (i.e., TC-PBT and TC-POT) or grafted by acrylonitrile. Both treatments resulted in an improvement in the mechanical properties of the resultant composites compared with the composites filled with the untreated wood fiber. Moreover, the grafting method displayed a more obvious benefit than that of titanate coupling methods to the mechanical property improvement. This was attributed to the crystalline structure of the wood fiber to be destroyed by grafting acrylonitrile, and the amorphous fiber was easily deformed to enhance fiber adhesion at the LLDPE matrix. In addition, the effect of the concentration of the filled wood fiber and the amount of coupling agent or grafting ratio on the mechanical properties of composites are discussed.

Epoxy resins toughened by poly(propylene carbonate)

Poly(propylene carbonate) (PPC) was used as a toughening agent for improving the brittleness of cured epoxy resins (EP). Methyl tetrahydrophthatic anhydride (MTHPA) was used as a curing agent. The activation energies for the reactions of PPC/MTHPA and EP/MTHPA measured by FTIR were 115.8 and 66.5 kJ/mol, respectively, while for the composite system of PPC/EP/MTHPA, the activation energy obtained from DSC was 52.9 kJ/mol. Gel contents, DMA, and DSC displayed that the cured resins of PPC/EP/MTHPA were phase-separation crosslinking systems and most of PPC could react with MTHPA or the epoxy group. The toughness of cured resins was reinforced by the addition of PPC. The optimum mechanical properties and toughness for cured resins of PPC/EP/MTHPA corresponded to the system containing 20 phr PPC, which achieved a 33% increase in tensile strength and a 45% increase in the fracture toughness at no expense of the elongation of cured resins.

Synthesis and characterization of aminated poly(2,6-dimethyl-1,4-phenylene oxide)

In this article, the chemical modification of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was carried out by incorporating an amine group into the PPO backbone. A maximum monosubstitution degree of 65 mol % was reached. The effects of reaction conditions on the functional group content in PPO is discussed. The aminated PPO obtained was characterized by FTIR, 1H-NMR spectroscopy, nitrogen analysis, DSC, solubility test, and X-ray diffraction studies. % 1996 John Wiley & Sons, Inc.

Study on nitrile-butadiene rubber/poly(propylene carbonate) elastomer as coupling agent of poly (vinyl chloride)/poly (propylene carbonate) blends. I. Effect on mechanical properties of blends

Nitrile-butadiene rubber/poly(propylene carbonate) (NBR-PPC) elastomer was studied as a coupling agent of the blends of poly(vinyl chloride) (PVC) with poly(propylene carbonate) (PPC). It greatly improved the PVC/PPC system mechanical properties that were dependent on the amount and composition of the coupling agent. When the coupling agent consisted of a 70/30 ratio of NBR/PPC (in which NBR had 34% nitrile content) and 2.5 phr of benzoyl peroxide (BPO) initiator and underwent a prevulcanization, the blends of PVC/PPC displayed excellent mechanical properties by adding 8 phr of the coupling agent.

Studies on miscibility of poly(phenylene oxide)-based ionomer/polystyrene-based ionomer blends

The phase behavior of series of blends obtained from mixing carboxylated poly(phenylene oxide) with sulfonated polystyrene and their respective neutralized ionomers was studied by differential scanning calorimetry. A substantially broader range of miscibility was observed when both blend components were functionalized, compared with blends in which only one of the components contained an acid group or was an ionomer. The properties of metallic cations which were used to neutralize the acid groups in the blends were found to have an effect on the miscibility. The miscibility of the two acid polymers or their ionomers depended on the difference of their functionalization level instead of on the absolute percentage of functional groups on each polymer. It was found that the two acid polymers or their ionomers remained miscible as long as they had a similar percentage of functional groups.

Studies on the blends of carbon dioxide copolymer. III. NBR/PPC systems

In this paper, the blends of the carbon dioxide copolymer, poly(propylene carbonate) (PPC), with nitrile rubber (NBR) were studied by DSC, DMA, TEM and TG. PPC can enhance the mechanical properties of NBR, while oil resistance and tensile set at break of NBR/ PPC systems were as good as that of NBR. The coagent of triallylisocyanurate or maleic anhydride with carbon black can much improve the curing efficiency of dicumyl peroxide in NBR/PPC systems.

Studies on the characterization of phase inversion during emulsification process and the particle sizes of water-borne microemulsion of poly(phenylene oxide) ionomer

In this article, the lightly sulfonated poly(phenylene oxide) (SPPO) ionomers in a series of mixing solvents were emulsificated by water to form a series of water-borne microemulsions. The phase inversion during the emulsification process of SPPO ionomer solutions was characterized by measuring the variation of conductivity, viscosity, and surface tension with the addition of water. The effects of properties of solvent systems on the phase inversion procedure, the particle size of emulsions with different solvent systems, and ionic contents of the polymer chain were discussed.

Structure and Properties of Poly(Propylene Carbonate)

Abstract Poly(propylene carbonate) (PPC), a new kind of aliphatic polycarbonate copolymerized by carbon dioxide and propylene oxide, was characterized by FTIR, 1H-NMR, 13C-NMR, DSC, TG, and viscosimetry. The copolymer chains consisted of alternative segments of carbon dioxide and propylene oxide and a small amount of homopolymer of propylene oxide. PPC fluid was pseudoplastic. Flow activation energy of PPC and quantitative relationship between apparent viscosity and molecular weight were obtained from their flow curves.

Single-ion conducting polymeric electrolytes based on sulfonated poly(phenylene oxide)

In the present paper, the ionic conducting properties of sulfonated poly(phenylene oxide) (PPO) and its alkali-metal salts were investigated in detail. It was found that the material had moderate conductivity, which could reach as high as 10 -6 S/cm at room temperature. Its conductivity dependence on temperature conformed to the Arrhenius equation in a temperature range of 20-90°C. The cations transference number determined by polarizing reversion was approximately unity. Differential scanning calorimeter, X-ray diffraction, and transmission electron microscope were used to analyze the condensed state structure of the material.

In‐situ composite based on polypropylene and nylon6

Polypropylene (PP) and Nylon6 were extruded with a single screw extruder. Nylon6 could form microfibrils in a PP matrix. When the blends were compression-molded at the temperature between the melting temperature of PP and that of Nylon6, these fibrils could be maintained in the matrix. The existence of Nylon6 microfibrils could improve the impact strength, but the tensile strength of the composites decreased. Differential scanning calorimetry (DSC) analysis show that Nylon6 microfibrils could affect the crystallization of PP slightly.