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In this work, a novel type of phosphorus containing hyperbranched polysiloxane (P-HBPSi) was synthesized by sol–gel method, and then utilized to functionalize graphene oxide (P-HBPSi@GO). The P-HBPSi@GO hybrids were mixed with TPU by melt compounding. The SEM observation revealed that the P-HBPSi@GO dispersed homogeneously in the TPU matrix with good compatibility. The TPU/P-HBPSi@GO-2.0 maintained high ductility with elongation at break of 1750.8%. The peak heat release rate and total heat release of TPU/P-HBPSi@GO-2.0 were reduced by 63.5% and 20.9%, respectively. In addition, the peak smoke production rate and total smoke production of TPU nanocomposites were also reduced dramatically by 58.3% and 36.4%, respectively. The production of phosphorus free radical scavengers in the gas phase and the barrier effects of GO nanosheets, catalytic charring and the unique Si-O-Si framework of P-HBPSi flame retardant in the condensed phase contributed to the outstanding flame retardancy and toxic gas suppression of TPU/P-HBPSi@GO nanocomposites.

The high flammability and generation of toxic volatiles during combustion are big obstacles for thermoplastic polyurethane (TPU). In this work, a 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivate containing phosphorus and nitrogen was synthesized and then grafted onto the surface of graphene oxide (GO-DOPO) by using a silane agent [(3-glycidyloxypropyl)trimethoxysilane] as the chemical bridge. Then the GO-DOPO was mixed with TPU by melt compounding to improve its flame retardancy. Tensile tests exhibited that the TPU/GO-DOPO nanocomposite maintained high ductility with a slight increase in tensile stress. The cone calorimeter tests exhibited that the incorporation of 2 wt% GO-DOPO into TPU presented a significant reduction in peak heat release rate (35.8%) and peak smoke production rate (50%), respectively, as compared with those of pure TPU. Meanwhile, the peak of CO production rate and the peak of CO 2 production rate decreased by 57.1% and 35.9%, respectively. The investigation of the flame retardant mechanism for TPU nanocomposites revealed that the presence of GO-DOPO in TPU contributed to generating the compact, continuous and higher graphitized char layer exerted barrier effect in condensed phase, protecting the underlying TPU matrix. This work provides a feasible functionalization approach of GO to enhance the fire safety of TPU nanocomposites without sacrificing the superior mechanical properties, which facilitates the promising applications of TPU in various fields.

Dielectric polymer composites with high dielectric constant and low dielectric loss are highly demanded for various types of devices. In this work, the core–shell structured polydopamine functionalized silicon carbide whiskers (SiC@PDA) were successfully synthesized. The presence of PDA effectively suppressed the dielectric loss of PVDF/SiC@PDA composites because it could inhibit the connection between fillers and reduce the interfacial polarity. Moreover, the thicker PDA layer contributed to improving dielectric breakdown strength and reducing AC conductivity of PVDF composites. The insulating PVDF/SiC@PDA-a-30 composite containing 30 wt% of SiC@PDA-a had a dielectric constant of 35.1 while the dielectric loss still maintained as low as 0.037 at 1 KHz. Meanwhile, PVDF/SiC@PDA-a-30 achieved the maximum stress of 58.8 MPa with elongation at break of 17.3% due to PDA layer improved the compatibility between SiC@PDA and PVDF. This simple coated PDA shell strategy could be extended to inorganic fillers to develop high performance dielectric polymer composites.

Polypropylene/ethylene-propylene-diene rubber (PP/EPDM) blends in situ compatibilized by magnesium dimethacrylate (MDMA) were fabricated via peroxide-induced dynamic vulcanization. Scanning electron microscope observation indicated that the size of cross-linked EPDM particles decreased with incorporation of MDMA. Polarizing Optical Microscope (POM) analysis suggested that the spherulite size of PP phase decreased sharply with incorporation of MDMA during dynamic vulcanization. The Pseudo-Avrami, Ozawa and Mo's models were applied to analyze the non-isothermal crystallization kinetics of the composites. The analyzed data indicated that the crosslinked EPDM particles and homopolymerized MDMA acted as heterogeneous nucleating agents, which enhanced the crystallizability and decreased the spherulite size of the PP phase. In addition, the non-isothermal crystallization activation energy (Δ E ) was calculated through the Kissinger and Friedman methods, and the Δ E value was found increase with incorporation of MDMA.

Plastic pollution has become a serious issue to the ecosystem, and biodegradable poly (butylene succinate)/polylactide (PBS/PLA) blends are regarded as the promising eco-friendly alternatives to replace the non-degradable plastics based on fossil fuels. Yet, the thermodynamically immiscible nature of PBS and PLA hinders their extended applications. In this contribution, nitrogen-doped graphene (NG) was introduced into immiscible PBS/PLA blends by melt compounding. The incorporation of NG in PBS/PLA (70/30 wt%) blends was observed to significantly improve the geometrical morphology and reduce the domain size of the dispersed PLA phase, indicating a compatibilization effect of NG on the immiscible blends. The TEM micrographs showed that the NG mainly dispersed in the PBS matrix while a small amount was located in PLA phase. When the NG concentration increased to 1.0 wt%, the NG filled PBS/PLA nanocomposites exhibited an obvious improvement in the storage modulus and loss modulus in comparison with the pristine PBS/PLA blend. The thermal stability of the PBS/PLA/NG nanocomposites was enhanced monotonously with an increase of the NG concentration, due to the barrier effect of NG and good interaction between the NG and polymer matrices. Moreover, the NG was noticed to act as a nucleating agent to significantly improve the PBS crystallinity without affecting the crystal forms of PBS and PLA. The tensile strength, tensile modulus and elongation at break of the blends could be enhanced by the low concentration of NG.

Dielectric polymer nanocomposites with high dielectric permittivity and low dielectric loss have great applications in energy storage field. In this study, a series of PVDF/MXene nanocomposites was prepared by solution method. The surface of MXene was functionalized with cetyltrimethylammonium bromide (MXene@CTAB) to achieve better dispersion in poly(vinylidene fluoride) (PVDF) matrix. The results revealed that the MXene@CTAB dispersed uniformly and had a good compatibility with PVDF matrix. In addition, the dynamical rheological test revealed that the viscosity and storage modulus of PVDF nanocomposites increased with the increasing of MXene@CTAB loading. The PVDF/MXene@CTAB nanocomposite containing 7 wt% MXene@CTAB exhibited a dielectric permittivity of 82.1 and a loss factor as low as 0.2 at 1 kHz. The presence of CTAB could serve as an insulating layer to suppress dielectric loss and AC conductivity of PVDF nanocomposites simultaneously. The PVDF/MXene@CTAB nanocomposite with high dielectric permittivity may find potential applications in energy storage capacitors for electronics. Moreover, the addition of MXene@CTAB contributed to the formation of Beta phase of PVDF.

The melting behavior and crystalline forms of isotactic polypropylene (iPP) samples crystallized under different conditions of pressure and temperature were investigated using differential scanning calorimeter (DSC) and wide-angle X-ray diffraction (WAXD), respectively. When treated with dynamic supercritical CO2(Sc-CO2), iPP samples undergo the formation of β-crystal that does not occur on the treatment with atmospheric pressure and static supercritical CO2(Sc-CO2) pressure. In addition, the relative content of β-crystal has deep dependence on melt state and depressurization rate. Depressurization plays very critical role in the formation of β-crystal by means of imposing three-dimensional tensile field during cell growth. The tensile field induced α-row nuclei where the formation of β-crystal occurred. This finding will provide one new method to induce β-crystal in iPP parts. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Free-radical reactions of polymers, including biodegradable polymers via reactive extrusion, are normally induced by peroxide chemicals, which are known to lead to the formation of secondary products and impart some performances to the resin. Here, we report an ultraviolet (UV)-induced reactive extrusion, without employing a peroxide initiator, to control chain scission and branching reactions of polylactide (PLA). Through this technique, chain scission reaction of molten PLA induced by UV irradiation during extrusion was promoted to high-level efficiency. Degraded PLA samples had lower complex viscosity and storage modulus, because of random main chain scissions. Long-chain branched (LCB) structure of PLA was obtained when a multifunctional chemical agent, trimethylolpropane triacrylate (TMPTA), was added into the PLA matrix during extrusion. Various rheological plots including viscosity, storage modulus, loss tangent, and Cole–Cole plots were used to distinguish the LCB structures of PLA samples. Therma...

Attributed to the wide applications of organic polyamines, the microencapsulation of polyamines with different physicochemical properties is promising for their new applications in other fields, such as self-reporting materials, self-healing materials, stimuli-responsive latent curing agents, etc. Herein, the versatility of the novel microencapsulation technique via integrating microfluidic T-junction and interfacial polymerization was demonstrated by encapsulating three typical polyamines with distinct physicochemical properties, i.e. tetraethylenepentamine (TEPA), meta-xylylenediamine (XDA), and polyetheramine JEFFAMINE T403. The microencapsulation processes for the three polyamines and the synthesized corresponding microcapsules were carefully studied in depth, and were correlated to the physicochemical properties of the polyamines. It shows that all the three polyamines can be successfully encapsulated by this technique, and the properties of the achieved microcapsules were highly influenced by their physicochemical properties. Polyamine mixtures consisting of TEPA/XDA and TEPA/T403 at different mass ratios were also encapsulated to tailor the properties of the microcapsules, showing that the polyamine with smaller molecule size contributes more to the shell formation. The results of this investigation provide theoretical guidance for the microencapsulation of other polyamines using this technique based on non-equilibrium droplets.

It is highly desirable to develop biodegradable UV-shielding materials from the renewable resources as the ever-increasing demand for the sustainable environment. In this work, TiO

Coating of antibacterial layer on the surface of cellulosic paper has numerous potential applications. In the present work, sodium alginate (SA) served as a binder to disperse Zn 2+ and the prepared zinc oxide (ZnO) particles were used as antibacterial agents. The rheology test revealed that there were cross-linking between Zn 2+ and SA molecular chains in the aqueous solution, resulting in the viscosity of ZnO/SA composite coating increased in the low shear rate region and decreased in the high shear rate region as compared with pure SA. SEM and EDS mapping images showed that the ZnO particles were prepared successfully at 120 °C and dispersed homogeneously on the surface of cellulose fibers and the pores of cellulosic papers. The thermal stabilities of the coated papers decreased as compared to the original blank cellulosic paper, which was ascribed to the low thermal stability of SA and the catalytic effect of ZnO on SA. The tensile stress and Young’s modulus of ZnO/SA composite coated paper increased up 39.5% and 30.7%, respectively, as compared with those of blank cellulosic paper. The antibacterial activity tests indicated that the ZnO/SA composite coating endowed the cellulosic paper with effectively growth inhibition of both Gram-negative bacteria E. coli and Gram-positive bacteria S. aureu .

In this work, rapid ozone degradation of polypropylene (PP) was developed for the aim of rheology control using a reactive extrusion process. Experiments were carried out in a co-rotating intermeshed twin-screw extruder with varied polymer throughput and reaction temperature. Ozone was introduced into the extruder to rapidly oxidize molten PP in just several seconds period. The oxidized PP was characterized through melt flow index (MFI), rheological measurement, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy tests. The influence of reactive temperature and polymer throughput on the degradation reaction was studied. It was noted that molten PP could be fast and successfully degraded during this reactive extrusion process. The oxidized PP had higher MFI than that of the origin PP resin, indicating the decrease of molecular weight of PP. Carbonyl groups were formed on the PP molecular chains. This rapid oxidization process has higher reaction efficiency than the ozone degradation of PP in solid state and no harmful byproduct would be generated from this ozonizing reaction.

Present studies on the topographic effects of substrates on cell functions are limited to planar substrates, which are usually not applicable in bone repair. Specific patterns are rarely constructed on 3D substrates. Here spherical substrates with macroporous topography were obtained to explore cellular responses. Macropores with tunable density were generated on the surfaces of poly(lactic-co-glycolic acid)/hydroxyapatite (PLGA/HA) microspheres by using HA particles as the pore-forming source. Different densities of macropores represented different topographies and were found to influence the morphology, proliferation and osteogenic differentiation of human fetal mesenchymal stem cells (fMSCs). The microspheres with a medium density of macropores most benefitted proliferation and differentiation of fMSCs compared with the low and high density ones. This study reveals the role of macroporous spherical surfaces in affecting cell function and may guide the design of functional substrates in bone repair.

Deeply oxidization of waster rubber crumb (WRC) by ozone treatment was carried out at room temperature with long time exposure. Gel content measurement, TG/DTG (thermogravimetric) analysis, ATR-FTIR (attenuated total reflectance-Fourier transform infrared) spectroscopy, XPS (X-ray photoelectron spectroscopy) and mixing properties tests were used to investigate the structure and properties of deeply oxidized WRC. After ozone oxidation, the gel content of WRC decreased dramatically in the first 3 h and then decreased slowly with prolonging the oxidation time. TG/DTG results showed that few low molecule weight materials were produced although ozone did destroy some cross-linking networks by oxidizing decomposition. ATR-FTIR and XPS spectrum showed the increase of oxygen-containing groups in WRC, indicating that oxidation reaction between ozone and WRC happened. Deeply oxidized WRC could form a uniform plate under pressure and heat due to regaining part of the flowability.

Three types of polypropylene, namely propylene homopolymer (HPP), block copolymer of propylene with ethylene (CPP-B) and random copolymer of propylene with ethylene (CPP-R), were melted and isothermally crystallized in a self-designed vessel under supercritical carbon dioxide (Sc-CO2) atmosphere. The melting behavior and crystalline forms of crystallized samples were investigated using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The results showed that the presence of Sc-CO2 could improve the crystallinity for all three polypropylenes, and the promoting effect was more obivious with increasing CO2 pressure. In addition, it was observed that γ-crystals could be obtained in the CPP-B and CPP-R samples crystallized under Sc-CO2, while no γ-crystals were formed in HPP under the given conditions. The relative content of γ-crystals obtained in CPP-R samples was much higher than that of CPP-B, and 100% γ-phase could be formed in the CPP-R sample when subjected to 14 MPa Sc-CO2.

Poly(butylene succinate) (PBS)/halloysite nanotube (HNT) nanocomposites were fabricated by melt compounding. The morphology of the nanocomposites was studied by scanning electron microscopy and the results showed that the HNT dispersed uniformly in the PBS matrix. The thermogravimetric analysis results showed that the addition of HNT decreased the decomposition temperature and activation energy, and thus accelerated the thermal degradation of PBS. The differential scanning calorimetry analysis indicated that HNT could serve as nucleating agent for the PBS, and thus increased its crystallization temperature and crystallinity. However, it was demonstrated by the X-ray diffractometry spectra that the incorporation of HNT did not affect the crystal form of PBS. Mechanical tests in flexure, tension, and notched Izod impact demonstrated that the strength and modulus of nanocomposites were increased by the addition of HNT without significant loss of ductility. POLYM. COMPOS., 35:847–855, 2014. © 2013 Society of Plastics Engineers

Polylactide (PLA)/halloysite nanotube (HNT) nanocomposites with different HNT contents were prepared by melt compounding. The morphology, crystallization behavior, as well as thermal and mechanical properties of the nanocomposites were studied. The results showed that HNT were well dispersed in PLA matrix. Thermogravimetric analysis data revealed that the thermal stability of PLA was decreased with the increasing of HNT content. Differential scanning calorimetry analysis indicated that the presence of HNT could promote cold crystallization and lead to different crystalline phase formation. The flexural and tensile modulus of PLA/HNT nanocomposites improved significantly with the incorporation of HNT. Compared with neat PLA foam, PLA/HNT nanocomposite foams showed much higher cell density and smaller cell size due to HNT serving as the heterogeneous nucleating agents. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A novel single screw extruder, with high transparent quartz glass as barrel, was employed to carry out reactive extrusion for ultrafast photo degrading molten polypropylene (PP). Ultraviolet (UV) was adopted to irradiate the molten PP to induce radical reaction and hereby to degrade PP macromolecules during extrusion. Compared with photo degradation of PP in solid state, reaction efficiency and uniformity in this process were greatly improved. Reactive degree was controlled by varying screw speed and photo-sensitizer (benzophenone, BP) concentrations. The structure and properties of degraded polypropylene was characterized by melt flow rate (MFR), Fourier Transform Infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and tensile properties test. After extrusion with UV irradiation, the melt flow rate increased and crystallization temperature decreased of the degraded samples. FT-IR showed no obvious C O groups were formed in molecular structure, indicating the oxidation reaction was very minimal.

We previously proposed a new strategy to replace a vitreous body with a novel foldable capsular vitreous body (FCVB). In this study, the FCVB was designed to mimic natural vitreous morphology, and evaluate its physiological functions compared with traditional silicone oil substitutes, in an established rabbit model of proliferative vitreoretinopathy. We found that FCVB was a very good replacement for closely mimicking the morphology and restoring the physiological functions, such as the support, refraction, and cellular barriers, of the rabbit vitreous body. The study has provided us with a novel research and therapy strategy that could effectively mimic the morphology and physiological function of the rabbit vitreous body.

We previously proposed a new strategy to fabricate a novel foldable capsular vitreous body (FCVB) as a vitreous substitute and found that the FCVB was a very good replacement for closely mimicking the morphology and restoring the physiologic function of the rabbit vitreous body. The aim of this article was to assess the mechanical, optical, and biocompatible properties of a FCVB made from liquid silicone rubber. The mechanical properties show that the shore hardness is 37.80 degrees, the tear strength is 47.14 N/mm, the tensile strength is more than 7.28 MPa, and the elongation ratio is more than 1200%; in addition, the FCVB has 300 nm mili apertures in the capsule. The optical properties reveal that transmittances are 92%, hazes are 5.74%, and spectral transmittance is 97%. The transmittance mission is 2.3% and can sustain a 1500 mW, 0.2 s, 532 nm green laser. The biocompatible properties are shown in the stable extracts experiment, no significant fever, good genetic safety, and no structural abnormality or apoptosis in the cornea, ciliary body, and retina over a 6-month observation period. These results indicate that the FCVB has good mechanical, optical, and biocompatible properties, and the assessment results can be recommended as the FCVB technical standards for industrial manufacturing and inspection.

A new method for identification of ethylene/α-olefin copolymer was established by Fourier Transform Infared (FTIR)–Differential Scanning Calorimetery (DSC) in this article. DSC and FTIR spectroscopy techniques were used to analysis the type and content of α-olefin in polyolefine copolymer. FTIR was available to identify the structures of polyethylene and copolymers of ethylene with different α-olefins. The type of polyethylene can be determined by the peak position of 1378 and 1369 cm−1. According to the peak location of 770, 784, and 895 cm−1, the type of α-olefin can also be determined. DSC method was used to decide the position of melting peaks. The quantitative investigation of the content of α-olefin in polyethylene was calculated by the formula: −ln(CH2 mol fraction) = −0.331+135.5/Tm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Single screw extruders are known as good melt pumps with the high, stable pressure needed for part extrusion. However they have a particular disadvantage in achieving good mixing. In a vibration-induced polymer extruder (VIPE), a vibration force field (VFF) is introduced into the whole extrusion process by the axial vibration of screw, which affects the mixing process. It is well-known that the total shear strain (TSS) has been widely used to measure the effect of melt mixing in a laminar system. In this study, an analytic model for pulsating TSS was developed and the TSS distribution of the melt in the screw channel of the melt conveying section in a VIPE was calculated to further understand the time-dependent dynamic laminar mixing process. A comparison of the TSS distribution of melt in screw channel with and without vibration shows that the TSS of melt increases with the application of vibration and the larger the vibration frequency and amplitude are, the larger the TSS that the melt may experience while melt traveling through the melt conveying section, which is favorable for melt mixing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Micromorphology and miscibility of thermoplastic vulcanized rubber (TPV) processed in the experimental equipment of vibrational induction for dynamic vulcanization are analyzed using SEM and FTIR. Experimental and theoretical results show that interpenetration and entanglement of macromolecular chains in TPV under vibration force field allow the formation of a thermoplastic interpenetrating network structure. In addition, the interfacial area of two-phase interpenetrating action increases and two-phase interface becomes less pronounced, which makes two-phase miscibility increase. With the increasing of vibrational frequency or amplitude, dispersed phase dimension decreases, the rubber phase becomes finer, and the flow resistance and dispersibility of rubber particles into the plastic matrix improves. Steady and dynamic samples are of similar molecular structure and the influence of steady and dynamic states on the type and relative number of feature absorption groups is not obvious. Dynamically processed samples are of better miscibility. Through reasonable selection of vibrational parameters, processing control of dynamic vulcanization, mixing dispersion, and reactant performance can be realized, and TPV with good comprehensive properties can be obtained.

Biodegradable poly(butylene succinate) (PBS) was melt compounded with halloysite nanotube (HNT) to prepare PBS/HNT nanocomposites, and both pure PBS and PBS/HNT nanocomposites were foamed successfully using supercritical carbon dioxide as a physical blowing agent. The cell morphologiesshowed that the cell size decreased, and both cell density and volume expansion ratio increased with the addition of HNT. Within the HNT content used in this work (1, 3, 5, and 7 wt.%), the content of 5 wt.% was found to be the one that lead to the smallest cell size and highest cell density and volume expansion ratio. In addition to the HNT content, both saturation temperature and saturation pressure were found to significantly influence the cell morphology. Higher saturation pressure led to smaller cell size and higher volume expansion ratio. Interestingly, a close-celled to interconnect open-celled morphology transition occurred for PBS/HNT nanocomposites at a saturation temperature of 120 °C. The formation of interconnect open-celled morphology was mainly attributed to the stress induced by the HNT in the cell solidification process. With the increase of HNT content, saturation temperature and saturation pressure, the enthalpy of fusion of the foamed samples increased.

An electromagnetic dynamic plasticating extruder, invented by the authors, was used to prepare isotactic polypropylene (PP) sheets. Tensile and impact tests show that the extruded samples can simultaneously be reinforced and toughened along the flow and transverse directions in a moderate frequency and amplitude range. The microstructures of the obtained samples were characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and scanning electron microcopy (SEM). The results indicate that the vibration plasticating extrusion affected the morphology of the PP extrudate, it especially resulted in finer spherulites, and move tie molecules, which account for the enhancement of the tensile strength and impact toughness of PP sheets in both extrusion and transversal directions.

A model of continuous melt transesterification of bisphenol-A and diphenyl carbonate in a continuous stirred tank reactor is developed using phase equilibria assumption and the method of molecular weight moments. The model equations can be simplified into a polynomial system that has 17 equations and 17 unknowns. Solution of the polynomial system gives out almost every aspects of the continuous transesterification process. Molecular weight and polydispersity index, end group ratio of hydroxyl to phenyl carbonate, contents of molecular species, and lost diphenyl carbonate fractions are studied in different operation parameters.

A model for investigating the melting process of polymer in a vibration-induced single-screw (VISS) extruder is presented. The key feature of this model is as follows: vibration force field is introduced into the overall course of extrusion by the axial vibration of the screw, and the velocity distribution in the polymer melt behaves strongly nonlinear and time-dependent. To analyze this model, half-open barrel visible experimental method and low-density polyethylene material are adopted to investigate the effect of the vibration parameters on the melting process, which goes into further details of study and research on the melting mechanism, and thus, a novel physical melting model is derived. Combining the conservation equations of mass, movement, energy, and constitutive, analytical expressions of the melting rate, the energy consumption, the length of melting section, and the distribution of solid bed are obtained. This model enables the prediction of the processing and design parameters in the VISS extruders from which the optimum conditions for designing VISS extruder and polymer processing are obtained. The theory is supplemented by a calculation sample and experiment, which shows that the introduction of vibration force field can improve the melting capacity and decrease the power consumption of extruder greatly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3860–3876, 2006

A simplified 2D melt film model was established to simulate the nonisothermal melt flow during the melting process of the vibration-induced polymer extruder of which the screw can vibrate axially. Since polymer has time-dependent nonlinear viscoelastic characteristic with vibration force filed (VFF), a self-amended nonisothermal Maxwell constitutive equation that can reflect the relaxation time spectrum of polymer was adopted. Using the 2D melt film model, melt films of two kinds of thickness representing different melting stages were simulated to investigate the influence tendency of the same VFF on the different melting stage. Special flow patterns and temperature distribution of melt in the melt film between the driving wall and the solid/melt interface with various vibration force fields were systematically simulated. It is found out that within a certain range of vibration strength, the application of vibration can optimize the time-averaged shear-rate distribution, improve the utilization efficiency of energy, and promote melting process; and the thinner the melt film is, the more intense the nonlinear viscoelastic response becomes with the same VFF; moreover, there exists optimum vibration strength to make the melting process fastest, which is in accord with the visualization experimental results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5825–5840, 2006

An analytic model has been developed to analyze the residence time distribution of melt in the screw channel of the melt conveying section in a novel extruder of which the screw can vibrate axially. A comparison of the residence time distribution of melt in screw channel with and without vibration shows that the residence time of melt increases with the apply of vibration and the larger the vibration frequency and amplitude are, the longer time it will take the melt to travel through the melt conveying section, which is in favor of the improvement of the effect of melt mixing. POLYM. ENG. SCI. 46:198–204, 2006. © 2005 Society of Plastics Engineers

We previously proposed a new strategy to fabricate a novel foldable capsular vitreous body (FCVB) as a vitreous substitute and found that the FCVB was a very good replacement for closely mimicking the morphology and restoring the physiologic function of the rabbit vitreous body. The aim of this article was to assess the mechanical, optical, and biocompatible properties of a FCVB made from liquid silicone rubber. The mechanical properties show that the shore hardness is 37.80 degrees, the tear strength is 47.14 N/mm, the tensile strength is more than 7.28 MPa, and the elongation ratio is more than 1200%; in addition, the FCVB has 300 nm mili apertures in the capsule. The optical properties reveal that transmittances are 92%, hazes are 5.74%, and spectral transmittance is 97%. The transmittance mission is 2.3% and can sustain a 1500 mW, 0.2 s, 532 nm green laser. The biocompatible properties are shown in the stable extracts experiment, no significant fever, good genetic safety, and no structural abnormality or apoptosis in the cornea, ciliary body, and retina over a 6-month observation period. These results indicate that the FCVB has good mechanical, optical, and biocompatible properties, and the assessment results can be recommended as the FCVB technical standards for industrial manufacturing and inspection.

The vitreous body has very important physiological functions, such as support, refracti on and cellular barriers. Although many artificial liquid or gelatinoid vitreous substitutes, including silicone oil, heavy silicone oil and hydrogels, have been injected into eyes after vitrectomy surgery, they cannot finely mimic the morphology and physiology of human vitreous body and can induce severe complications. We had proposed a new strategy to fabricate a vitreous substitute by a novel foldable capsular vitreous body (FCVB) and found that it was a very good replacement for closely mimicking the morphology and restoring the main physiological function of the rabbit vitreous body, without the obvious complications commonly induced with traditional silicone oil. It may be a novel alternative to silicone oil and will make vitrectomy surgery simpler and as effective as current intraocular lens implantation surgeries.

Copolymer gels were prepared from 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS), N,N-dimethylacrylamide (DMAA, comonomer) and N,N′-methylenebis(acrylamide) (BIS). The mole fraction of AMPS were 0.2674 and 0.4318, respectively, with the same BIS mole fraction of 0.013. These gels with counterions H+, Na+, and K+ were swollen at 25°C in mixtures of dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF). A volume phase transition was observed at the THF volume fraction of about 0.58, indicating that the volume phase transition in a polyelectrolyte gel occurs when the medium polarity decreases sufficiently for ion-pair formation. On changing the counterion, the fraction of DMSO in the solvent mixture which is required to initiate swelling decreases in the order Na+, H+, and K+, the same as for counterion condensation in identical gels.