Advanced Materials Research Vols. 941-944

Abstract: A self-oscillating polymer chain consisting of N-ethylacrylamide (NEAAm) and a Ru catalyst of the BelousovZhabotinsky (BZ) reaction was prepared. The polymer chain underwent soluble-insoluble self-oscillation induced by the BZ reaction, originating from the differing solubility of the Ru moiety in the reduced and oxidized states. The amplitude of self-oscillation was small compared to that for the polymer chains prepared from N-Isopropylacrylamide (NIPAAm). The activation energy observed with the novel, NEAAm-based polymer chain was 68 kJ/mol, similar to that found with the NIPAAm-based polymer chain and normal (no Ru catalyst incorporated in the polymer) BZ reaction.

Abstract: The octane-succinyl-chitosan (C₈-SCCHS) was synthesized by modifying chitosan (CHS) , characterized by IR, ¹H NMR, WAXD and octane-succinyl-chitosan/polyethylene glycol (C₈-SCCHS)/PEG interpenetrating polymer network (IPN) hydrogel was prepared by croslinking of C₈-SCCHS and PEG. The swelling behaviors of hydrogels in different pH solutions have been studied. The pH sensibility were researched. Micromorphology of the external surface of the hydrogels were imaged by scanning electron microscopy (SEM). Aciclovir as a model drug to study the performance of their release. The results show that the gels have porous cross-linked network structure, which is beneficial to absorbing water or drug, and have ability of controlled release for aciclovir.

Abstract: Aimed at the main factors of hot rolled strip steel product width fluctuation, rolled piece is put forward to plasticity coefficient and entrance width as the input variables of feedforward AWC control algorithm.Expounds a kind of optimization of plasticity coefficient Q feedforward AWC control system principle and plasticity coefficient Q of linear prediction algorithm.Field application shows that the Q prediction feedforward AWC has significant effect on inhibition of hot rolled strip width deviation.

Abstract: In this study, curled gelatin nanofiber was successfully electrospun from aqueous solution by elevating the spinning temperature. The effect of relative humidity was investigated on the morphology of gelatin nanofibers in the current study. It was observed that with the increase of relative humidity during electrospinning process, the proportion of the curled gelatin nanofiber increases. Futhermore, the curled gelatin nanofiber converted into helical structure when electrospun at relative humidity higher than 50%.

Abstract: Injection-molded β-isotactic polypropylene (β-iPP) specimens were prepared by adding three β nucleation masterbatches, i.e., NT-MA, NT-MB and NT-MC, respectively. The melting, crystallization and mechanical properties of β-iPP specimens were investigated by means of differential scanning calorimetry (DSC) and mechanical tests. It is revealed that β crystalline form contents were enhanced by the β nucleation masterbatches, and the β contents of the cores were higher than those of the skins of injection molded specimens. The tensile strain at break and Izod notched impact strength of iPP were greatly improved by the β nucleation masterbatches. It was found that the β nucleation efficiency was in the order: NT-MC > NT-MA > NT-MB.

Abstract: Our previous research showed that the presence of more rigid segments of p-phenylene in the PSA copolymer backbone enhanced the strength and modulus of the fiber. Poly (4,4'-diphenylsulfone terephthalamide) referred to as all para-position PSA, which was synthesised only by 4,4'-diaminodiphenylsulfone (4,4’-DDS) and terephthaloyl chloride (TPC), and it was expected to have best mechanical properties. As it cannot be easily dissolved in common amide-type polar aprotic solvents, N,N-dimethylacetamide (DMAc)/LiCl and DMAc/CaCl₂ solvent system was used to solve this problem. Static state rheological properties of all para-position PSA spinning solutions were investigated by measuring the apparent viscosity versus shear rate at different concentrations and temperatures. The effectiveness of cosolvent like LiCl and CaCl₂ in the solvent system were investigated, the results showed that LiCl was more effective than CaCl₂.

Abstract: A model for the isothermal flow-induced crystallization (FIC) of polypropylene melt in a simple shear flow is developed. The model is based on the molecular kinetic theory. The first normal stress difference of the stress tensor, calculated according to a molecular model, is assumed as the driving force of the flow-induced nucleation. Crystallization is described as a spherulitical nucleation and growth process. The theoretical predictions of the evolution of the viscosity in steady shear flow of iPP are in agreement with the experimental findings. The relative influence of the mechanical and thermal phenomena on the crystallization development is then analyzed as a function of the shearing intensity in terms of nucleation density. The results show the enhancement of the crystallization kinetics due to the shearing.

Abstract: In the CFRP integrated manufacturing process based on RFI process, a CFRP stacking sheet is fabricated by laying alternatively Carbon Fiber Fabrics on Epoxy Resin Films each other. So its infusion process can be regarded as a concurrent infusion system consisting of some representative infusion systems with the delay time. Where, each representative infusion system includes a single layer resin film and a single layer carbon fiber fabric. It means that the infusion behavior of a CFRP stacking sheet can be described as a combination of the time delay from the bottom layer to the top layer and the required infusion time of the top representative infusion system. Based on this idea, the infusion behavior of the CFRP stacking sheets with different infusion pressures and the number of layer of Carbon Fiber Fabric is researched with the aid of the simulation software of RFI process developed especially and experiments, whose objects is to discover the impacts of the number of layer of Carbon Fiber Fabric and the infusion pressure on the resin infusion behavior. It is noticed that the predicted results have a good agreement with the experimental ones, which also verifies the applied method in this paper is feasible and valid to determine proper process conditions of the CFRP integrated manufacturing process.

Abstract: Poly (p-phenylene terephthalamide) (PPTA) was synthesized by different processes including single feeding, batch feeding and inlet nitrogen cooling. The effects of these three processes on reaction heat removal of PPTA polymerization were compared. The degree of reaction heat removal was characterized through the changes of system temperature and stirring rate with reaction time. Results suggested that during the processes of batch feeding and nitrogen cooling, system temperature could be effectively decreased and PPTA yields were both larger than 98 %. It indicated that the exothemic heat could be transferred faster and better and monomers could completely react. The inlet incorporation of nitrogen cooling led to the maximum of inherent viscosity (η_inh) of resulted PPTA. This result indicated that nitrogen cooling could effectively transfer the reaction heat and prolong the gel precipitation time of PPTA.

Abstract: Polypropylene (PP)/Maleic anhydride grafted poly (ethylene-octene) (POEg) were prepared by melt blending method. The crystallization behavior and crystal morphology were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarzing optical microscope (POM). Differential scanning colorimetry (DSC) experiments showed that the melting point and crystallization point decreased when POEg added to the blend. XRD results show that the POEg not change the crystal structure in the blends but only decrease the intensity of the diffraction peak. The spherulitic structure could also observed when added POEg to the matix of PP, but the shape of the spherulites distorted.