Hyaluronic Acid(HA)is a naturally derived,nonimmunogenic, nonadhesive glycosaminoglycan that plays a prominent role in various wound-healingprocesses,because its poor stability in the human body,it is necessary to modify the HA to get a higher molecular.Among the various way of improving the stability,crosslinking is a more easy way.High-energy radial is an effective way to form branches and crosslinkings. The free radicals appeared when the high-energy radial functioned on the polymer chain.The branches and crosslinking formed after the free radicals reacted to each other.It is a so effective way to get crosslinked structure that does not need any initiator or catalyzer.The high-energy radial applied to the modifying of HA will be a novelty way to get HA derivatives with high character of high purity,high crosslinkage and nontoxic.We focused on two most important aspect while experimentalizing:first we should change the structure of HA,then we must asure the salty of the product.We first tried Ultraviolet radiation,Microwave andγ-radial to find out which one is best.We choseγ-radial after compared with the other two,then we usedγ-radial to further study the crosslink of HA.It is necessary to add some cross-linking agent while doing the cross-linking because of the degradation theγ-radical did to HA.We chose Glycidyl Methacrylate(GM)to function as the cross-linking agent,not because it has double bounds,but also the good biocompatibility.We summarized that the molecular weight of HA,the concentration of GMHA and the dosage ofγ-radical were the most important factors that had obvious effect on the crosslinkage of HA.If control these factors properly,we can achieve the aim of preparing HA derivatives with controlled crosslinkage.At last,we prepared highly crosslinked HA liquid and study the rheology. We find that the rheology performance of the HA derivative we prepared has the accordance of the pseudoplastis fluid.Then we can summarize that this way of modifying can keep the rheology performanceof HA.
Post about "crosslinking"
Hypersonic spacecrafts need withstand extreme conditions at re-entry in Earth’s atmosphere. Especially, the nose tip and leading edge need operate at ultra-high temperature and high heat flux for long time in oxidized environment, so that it is necessary to develop new thermal protection materials. On the base of ultra-high temperature materials research abroad and at home, this dissertation investigated ultra-high temperature carbon matrix composites. New ultra-high temperature composites C/C-ZrB2(ZrC, TaC) were fabricated by introduction of ceramic powder (ZrB2, ZrC, TaC) using slurry brushing process, and introduction of carbon matrix using polymer infiltration and pyrolysis method. We studied the influence of precursor, crosslinking, infiltrating and puncture techniques on the composites structure and property.We chose furan resins, phenolic resins and pitch as the source of carbon, and investigated the influence of crosslinking and infiltrating on the composites structure and property. The C/C-ZrB2 composites were prepared by infiltration-crosslinking-pyrolysis process by using furan resins, only to find that the resins will expand and shrink in process of crosslinking and pyrolysis, thus leading to poor adherence between layers and poor performance of the composites. The C/C-ZrB2 composites prepared by infiltration-pyrolysis furan resins display high densification, good mechanical properties and oxidation resistance.The composites prepared by using phenolic resins, on the other hand, can enhance densification effectively through infiltration-crosslinking-pyrolysis process, thus improve significantly mechanical properties, oxidation resistance and ablated resistance. The composites prepared by infiltration-pyrolysis process showed low density, poor mechanical, oxidation resistance and ablated resistance properties.The C/C-ZrB2 composites were also prepared by infiltrating pitch of molten and solution. The sample from melt pitch has good integration performance, while that from solution has lower density and poor mechanical properties. However, the melting infiltration process requires high temperature and high pressure equipment, and thus high cost. In conclusion, phenolic resins is the suitable precursor for polymer infiltration and pyrolysis process, and the composites prepared by infiltration-crosslinking-pyrolysis process is first-rank.We investigated the influence of ceramic content on the composites (C/C-ZrB2, C/C-ZrC, C/C-TaC) structure and property. The density of C/C-ZrB2 composites increases when the content of ZrB2 increase, while linear recession rates in oxyacetylene torch test decrease first and increase later. Among all samples ZB10 sample (10vol% ZrB2) has the best integration performance with 250.37MPa flexural strength and 13.84MPa·m1/2 fracture toughness. After being oxidated at 1200°C for 30min, its mass retention and strength retention were 90.65% and 85.14%, respectively. Meanwhile, it also shows best ablation resistance. After being ablated in oxyacetylene torch for 60 seconds, the sample showed mass loss rate of 0.01802g/s and linear recession rate of 0.0122mm/s. ZC15 sample (15vol% ZrC) shows the relatively excellent integration performance with 217.54MPa flexural strength and 12.00MPa·m1/2 fracture toughness. After being oxidated at 1200°C for 30min, its mass retention and strength retention were 90.91% and 82.04%, respectively. It also has better ablation resistance with the mass loss rate of 0.01827g/s and linear recession rate of 0.0193mm/s. The density of C/C-TaC composites increases when the content of TaC increase. TC15 sample (15%vol TaC) has the best integration performance with 260.99MPa flexural strength and 13.21MPa·m1/2 fracture toughness. After being oxidated at 1200°C for 30min, its mass retention and strength retention were 92.12% and 75.03%, respectively. It also presents relatively good ablation resistance with mass loss rate of 0.02510g/s and linear recession rate of 0.0290mm/s.The influence of puncture process on the composites performance was investigated. Puncture process can enhance densification of C/C-ZrB2(TaC, ZrC) composites, reduce the opening porosity, improve shear strength. At the same time, puncture process can also decrease high heat flux erosion and keep integration performance during ablation. Contrast with un-punctured sample, the linear recession rate of C/C-ZrBB2 composites was reduced to 0.0075mm/s from 0.0135mm/s.
Study on the Structure and Capability of the Thermally Crosslinkable Multi-block Copolymers Synthesized via Mannich Polycondensation
An important strategy for making polymer materials with combined properties is to prepare block copolymers consisting of well-defined blocks via facile approaches.In this thesis, Poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymers (PH-alt-PDMS) were synthesized via Mannich polycondensation involving phenolic hydroxyl-terminated poly(hydroxyether of bisphenol A), diaminopropyl-terminated polydimethylsiloxane and formaldehyde. The polymerization was carried out via the formation of benzoxazine ring linkages between poly(hydroxyether of bisphenol A) and polydimethylsiloxane blocks. Differential scanning calorimetry and small-angle X-ray scattering show that the alternating block copolymers are microphase-separated. Compared to poly(hydroxyether of bisphenol A), the copolymers displayed enhanced surface hydrophobicity (dewettability). In addition, subsequent crosslinking can occur upon heating the copolymers to elevated temperatures owing to the existence of benzoxazine linkages in the microdomains of hard segments. The subsequent self-crosslinking of the PH-alt-PDMS alternating block copolymers could lead to these polymer materials having potential applications.Poly(benzoxazine of 4,4′diaminodiphenylmethane) -b- polydimethylsiloxane multi-block copolymers (PBDDM-b-PDMS) were synthesized via the Mannich polycondensation between the phenolic hydroxyls-terminated poly(h benzoxazine of diaminodiphenylmethane) with variable molecular weights and diamino-terminated polydimethylsiloxane (ATPDMS) by one pot. The micro-separated morphology of the alternating block copolymers was proved by Atomic Force Microscopy and Small Angle X-ray scattering, and the nanodomains of PDMS were dispersed in the crosslinked polybenzoxazine matrix. Non-isothermal differential scanning calorimetry (DSC) at different heating rates is used to determine the kinetic parameters of the curing processes of the PBDDM-b-PDMS. Compared to the control polybenzoxazine, the PBDDM-b-PDMS had higher activation energy and less enthalpy of the curing reaction. Thermogravimetric analysis (TGA) was applied to evaluate the thermal stability and the surface properties of the copolymer were investigated in terms of the measurement of static contact angle.
In this thesis,three kinds of different superabsorbents were prepared by aqueous polymerization using several kinds of different monomers,and both the properties of the resultant superabsorbent and the variables that had influence on the properties of the superabsorbent were mainly discussed in this thesis.The main results were obtained as follows:（1） As the effects of PVA content on water absorbency of the resultant superabsorbent reported by the literatures were not identical.A superabsorbent with semi-interpenetrating network was prepared by solution polymerization using maleic anhydride（MAH）,acrylamide（AM） and poly（vinyl alcohol）（PVA） as raw materials. The effects of PVA content on water absorbency,swelling rate and salt sensitivity to saline of the superabsorbent were examined in detail before which the synthesis conditions were optimized.The results showed that with the increment of PVA content, the water absorbency of the resultant samples would first decrease and then increase.In addition,the samples would have higher swelling rate and became less sensitive to saline.（2） As the water absorbency of the first superabsorbent is very low,a superabsorbent with improved water absorbency in physiological saline was prepared by solution polymerization in which a strengthened ionic monomer was added into reaction mixture. But the results showed that such method can only work when the superabsorbent was immersed into solutions containing monovalence cations.When immersed into solutions with higher valence cations such as A13+ the superabsorbent still had low water absrorbency.So the previously mentioned method can not fundamentally solve the problem that most superabsorbents have poor salt-resistance properties.Comparing with the effect of cations with different valence on water absorbency of the superabsorbent,the effects of anions with different valence on water absorbency of the superabsorbent seem much less.Besides,we also found that the resultant superabsorbent had nice water-retention properties.Even being dried for 6 h at 90℃,the superabsorbent can retain more than half of its original absorbed water,as a result of which the superabsorbent can be expected to be used in agriculture and horticulture.（3） A superabsorbent resistant to saline solution was prepared from copolymer of partially neutralized MAH、acrylic acid（AA） and AM by solution polymerization using Vc-H2O2 as an initiator and both trihydroxymethyl propane glycidol ether（6360） and N,N’-methylenebiacrylamide as crosslinkers.The effects of molar ratio of AA to AM, degree of neutralization of AA,volume of reaction mixture,temperatre of reaction,the amount of crosslinker and initiator on water absorbency were investigated.The results showed that water absorbency of the superabsorbent in 0.9 wt%NaCl solution can reach 77g/g.
In view of the nickel processing during the missile manufacturing in PLASecond Artillery Corps, the processing waste water recycles with great difficulty,the resin was synthesized by cross-linking chitosan with glutaraldehyde andwith Ni2+ as template.Chitin is a kind of crude macromolecule material inthe present thesis. The production of chitin which has been removed acetylis called chitosan. They has a preferable application in the field ofWastewater disposal。The adsorption behavior of chitosan on Ni2+ was studied. Thestructure and morphology of the complexes was obtained by FTIR and SEM.The adsorption capacity of the complexes of CTS-Ni2+ on different metalions was also studied. The crosslinking degree of the resin is increasingwhen the dosage of glutaraldehyde has been increased, but it remainsunchanged when the ratio of raw materials reaches a certain volume;Crosslinking degree of the resin is increasing with the enhancement oftemperature and time of the reaction system. The major factors that affectthe adsorption capability of chitosan are adsorption time, quantity of theresin, initial ionic concentration, pH of the medium etc.The structure was identified by FTIR and SEM, in order to study themajor factors that affected the adsorption process. The result indicates thatthe -NH2 of the resin and Ni2+ have reacted. Through SEM we can concludethat cross-linking chitosan may be more conducive to adsorption.Adsorption influencing factor of the resin on Ni2+ were studied. Theadsorption experiment shows that the adsorption time is about 4h. As the pHvalue is increasing, the adsorption capacity of the resin on Ni2+ increases.The adsorption capacity reaches a maximum when pH is 7.08.0. But when pH> 8.0, it is on a declining trend. In the temperature ure range of 30℃to 40℃, the adsorption capacity increases with temperature increasing, but theadsorption capacity is on a declining trend when the temperature continuesto rise. The resin which has a little change on weight and adsorptioncapacity after regeneration, can be reused.
Synthesis of Liquid Crystalline Polymers and Elastomers Containing Chiral Groups and Fluoronatied Units
Due to the advantages of fluorinated liquid crystals, such as low viscosity, high resistivity, good stability, suitable dielectric constant, rapid response and so on, fluorinated liquid crystalline materials become very important in the display field.It is fluorine’s small size, large electronegativety, and large fluorine-fluorine repulsion that lead to many excellent properties of fluorinated liquid crystals. Based on the different positions of fluorine atoms or fluorinated groups in molecules, fluorinated liquid crystals are classified in three species: liquid crystals bearing fluorine atoms or fluorinated groups as terminal groups, liquid crystals containing benzene ring with hydrogen atoms substituted by fluorine atoms, and liquid crystals with central bridge bond having hydrogen atoms substituted by fluorine atoms. According to the difference of liquid crystalline system in which they are, the changes of position and number in molecules, fluorine atoms make fluorinated liquid crystals possess diverse properties. At the same time, side-chain and terminal fluorinated compounds can raise the solubility of other liquid crystals in mix LCs due to fluorine’s greasy solubility. For these reasons, fluorinated liquid crystals provide a wide choice for the deployment of various high-performance mixed-LCDs.In this dissertation, six liquid crystalline monomers were synthesized, which include 4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoyloxy) phenyl 4- (undec-10-enoyloxy) benzoate(M1),4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoylperoxy)phenyl 4-(ally loxy)benzoate(M2),6-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoyloxy) hexa hydro furo[3,2-σ]furan-3-yl 4′-(undec-10-enoyloxy)biphenyl-4-ylterephthalate(M3), Hexahydrofuro [3,2-σ]furan-3,6-diylbis(4-(allyloxy)benzoate)(M4), Biphenyl-4,4′-diylbis(4-(allyloxy)ben zoate)(M5),cyclopenta[(?)]phenanthren-3-yl 4-(allyloxy)benzoate (M6). And then fluorinated monomers,2-(allyloxy)oxirane(M7), chiral monomers were grafted to linear polymethylhy drogensiloxanes. So four series of liquid crystalline polymers(LCPs) with different chemical structures and characters were synthesized.Polymers side-chain liquid crystalline elastomer were P1 and P2 series. Especially, fluorinated monomers and the four fluorinated side-chain liquid crystalline polymers were first prepared,they have important theoreticalvalue, and provides the development and application with technology support. The structures and properties of the obtained liquid crystalline monomers, crosslinking agent, LCPs and LCEs were investigated by FT-IR spectroscopy,1H-NMR spectroscopy, differential scanning calorimetry (DSC) and polarizing optical microscopy (POM), Their structure-property relationships were discussed in detail.In this dissertation, the structures of the three monomers and four series of LCPs were analyzed and proved.They have series of liquid crystalline texture. With increasing the concent of non-mesogenic crosslinking agent, Tg of P1 series and P2 series decreased firstly, and then increased; Tg of P3 series decreased in principle; Tg of P4 series increased on the whole. The four series of LCPs were liquid crystalline polymers. The effect of the content of crosslinking agent on phase behavior and thermal properties was discussed.
Aromatic polymer poly (aryl ether ketone) s since its inception, particularly in the early eighties after the success of development and utilization of PEEK, the development of such special engineering plastics has aroused great attention. The Tg of PEEK of is143℃, Tm is 334℃, and its using temperature is at 240℃. Despite the overall high performance PEEK, but in order to meet the special requirements of certain high-tech fields, demanding higher levels of heat-resistant products. In order to improve the using temperature of poly-aryl ether polymer, synthesis of structurally related polymers containing more rigid chains, which have higher Tg and Tm, have been studied broadly. However, with the increasing of Tm accompany the processing great difficulties. Poly (aryl ether ketone) s is not only excellent heat resistance and good toughness, rigidity, electrical properties, resistance to radiation, resistance to fatigue, impact resistance, creep resistance, wear resistance, heat water is good, and good flame-retardant etc., in the field of thermoplastic polymer occupies an extremely unique important combination. In recent years, preparation of functional poly aryl ether ketone studies to become a hot spot to prepare functional poly aryl ether ketone the most effective way is to have some functions of the special nature of compounds by chemical methods (grafting, copolymerization, etc.) or physical methods (blend) introducing PAEK. To further enhance the poly aryl ether ketone polymer properties to meet certain special circumstances, the use of requirements (such as high temperature, high radiation intensity, and optical electrical materials), it is made them to take place cross-linking reaction. Before cured processed they are thermoplastic materials, and then become thermo set through cross-linking reaction, so they have both kinds of advantage of materials. They’re required to introduce cross-linking groups. We have adopted the form of capped phenylethynyl and phthalonitrile groups to introduce PEEK structures, through these two groups at a high temperature cross-linked to achieve the intended purpose. The dissertation includes three parts: The first study is about phenylethynyl terminated PEEK oligomers and its composites; the second part is on cyano-terminated PEEK oligomers cross-linking behavior of the study, the third part of the hyperbranched polyether ether ketone polymer cross-linking behavior research.Three different molecular weight of phenylethynyl terminated oligomer (PE-PEEK-n) were prepared to using the monomers FPEB, hydroquinone and 4, 4′-Difluorobenzophenone. Their structure and composition were characterized by IR and elemental analysis. The thermal properties were investigated by differential scanning calorimetry (DSC), under the heating influence the phenylethynyl groups can conduct its own cross-linking reaction. Initial results indicated that the peak temperature of exothermic peak decrease follow with increasing content phenylethynyl group. After cured reactions, the glass transition temperature is the opposite trend. TGA testing the cross-linked oligomers have very good thermal stability, and cross-linking process did not produce small molecules. PE-PEEK-n series of oligomers of the initial complex viscosity is very low, between its melting point above and the lowest temperature of the viscosity have a processing window, with the constant cross-linked oligomers, complex viscosity, storage modulus and loss modulus increased after cross-linking completely, can basically meet the requirements of RTM molding process. Preparation of resin and glass fiber composite materials, the composite material has good mechanical properties, resin matrix, after cured two layers of fiber is well bonded together.We used bisphenol monomer and 4-nitrophthalonitrile prepared by nucleophilic substitution reaction of a series of phthalonitrile end capped PEEK oligomers. Capped by different feed ratio the oligomers can be divided into two types of substitution and monosubstituted. Their thermal performances were investigated by DSC. After heated at 225℃for various times, the CN-PEEK can be thermal polymerized. The self-promoted cure behavior of CN-PEEK compound is closely correlated to its hydroxyl unit. Compared to the CN-PEEK, the 2CN-PEEK oligomer was cured in the presence of p-BAPS via heating its powders up to 275–375℃. When the -CN and the electron-withdrawing group -CO- short distance the cross-linking reactions at lower temperatures. The final cured products displayed excellent thermal properties. The cured reaction mechanisms of phthalonitrile terminated PEEK oligomers need further studies.We synthesized two kinds of different functional group ratio nitrile-based end-capped hyperbranched polyether ether ketone (CN-HPEEK). The results proved the cyano group was introduced into the polymer successfully. We can use less of the cross-linking curing agent to complete cross-linking reaction, measured by TBA method obtaining the glass transition temperature significantly elevated, TGA measured by cross-linking greatly improved heat resistance proved that the occurrence of cross-linking reaction. Infrared Testing also showed that the -CN characteristic absorption peaks at significantly decreased under the action of heat.In summary, these two kinds of cross-linked PEEK oligomers (polymers) can be used as composite matrix resins. We can further investigate its composite materials processing technology and its mechanical properties, composite materials, for design and manufacture to provide a broader selection space.
In recent years, as one of the three pillars of modern communication network, optical fiber communication have been rapid growth.Many countries devoted a large number of manpower and resources to the seminars.As one of the basic components in optical fiber communication, optical waveguide devices have received increasing attention. Polymer materials were introduced to optical waveguide devices under development for its excellent workability, facile construction technology, strong chemical stability and low cost.The polymer optical materials should satisfy several requirements. First, it should have a low optical transmission loss especially at the telecommunication wavelength region of 1310 and 1550 nm.Second, in order to ensure that the small radius of curvature of polymer waveguide, it should have tunable refractive index (RI). Third, it should have the low birefringence to avoid polarization dispersion. Last, in order to adapt to the different devices use environment, materials should have excellent thermal stability, chemical stability and low water absorption. Fluorinated polyimide materials with its excellent thermal stability, good solubility, light transmittance and low moisture absorption rate have received the people’s attention. As the waveguide material to its corresponding wide range of studies carried out up.A great deal of effort has been concentrated on the preparation of polyimides containing crosslinkable moieties.For the fabrication of awaveguide device, a crosslinked polymer system has several advantages such as increased thermal and thermo-stability, chemical resistance, gap filling ability, and improved adhesion properties at the substrate. Containing phenylethynyl moieties polymers are good candidates for crosslinked optical waveguide materials due to easy synthesis, absence of an aliphatic C–H bond leading to significant optical absorption loss, greater process control over the ethynyl group due to its wider processing window,and absence of catalyst and evolution of any volatile during the curing reaction. The incorporation of phenylethynyl moieties into polymers has been studied extensively. The most common approach has been to introduce the phenylethynyl groups as end caps on oligomers which can then be molded into the final shape and subsequently crosslinked by heating.In the first part, we designed and synthesized a series of phenylethynyl terminated fluorinated polyimide oligomers using [1,4-(4-amino-2- trifluoromethyl-phenoxy)-2-(3'- trifluoromethylphenyl)benzene] as a diamine, 4,4′-(Hexafluoroisopyrilidene) diphthalic anhydride (6FDA) and 4,4′-Oxydiphthalic anhydride (ODPA) as dianhydrides and 4-(1-phenylethynyl)- 1,8-naphthalic anhydride (PENA) as an endcapping reagent. The oligomers were thermally crosslinked at 370°C for 2 h and showed high thermal stability. The temperatures at 5% weight loss were up to 540°C under nitrogen atmosphere. These PETI oligomers exhibited very good solubility behavior at room temperature both in strong aprotic solvents and in common organic solvents. After crosslinking, they have good chemical resistance, so it will not cause intermixing by solvents between layers by spin-coating. Also, they have low inherent optical absorption at the near-infrared region for polymeric optical waveguide materials. The refractive indexs of their films were controlled in the range of 1.5515–1.5976 at 1550 nm.In the second part, the fluorinated triamine monomer and commercially available dianhydride monomers were condensed to afford a series of anhydride-terminated poly(amic acid)precursors, then the precursors were end-capped by 3-trifluoromethyl-4-(phenylethynyl) aniline (3FPA) and chemically imidized to yield a series of phenylethynyl -terminated hyperbranched polyimides (HBPIs). These HBPIs were readily soluble in a variety of organic solvents such as NMP, DMF, THF, and cyclohexanone. The good solubility of these polymers in common organic solvents is profitable for the fabrication of the films for waveguide optical devices. We can see that the introduction of phenylethynyl crosslinkable groups at the end of the polymer is helpful for the fabrication of multilayered optical waveguides. We test the near-infrared absorption of our polymers.At the key telecommunication wavelengths of 1310 and 1550 nm, both polymer films show low light absorption. Such types of fluorinated hyperbranched polyimides are potentially useful for optical waveguide applications.
In the paper, the foamed thermoplastic polyester elastomer(TPEE) boards have been prepared by melt extrusion with a single screw extruder, which are a new type of track materials with high damping properties. At present, the foamed TPEE boards have been mainly used as damping pads under the steel rail in the ballastless track of high-speed railway.Firstly, the composite foaming agent of TPEE have been prepared with a twin-screw extruder used as a reactor. when the mass ratio of azodicarbonamide(AC)/sodium bicarbonate(NaHCO3)/citric acid is 15/5/5, and the foam-coated agent was acrylates, the apparent density can reach to 0.6 g/cm3, tensile strength was 5.6 Mpa, at the same time, about 75% in the certain area is made up by cell between 40 and 120μm.Secondly, TPEE with shore hardness D40 or D45 has been crosslinked by isocyanate and epoxy crosslinking agent respectively. The gel content increased with the raise of crosslinking agent, when the content of isocyanate crosslinking agent is lphr, the compression set for foamed TPEE with Shore hardness D45 is less than 10%, and the cell less than 100μm account for 90% of all the number of cell in the certain area approximately. In the constant frequency, damping factor tanO is greater than 0.25, and damping temperature range is 130℃, so the crosslinked TPEE is poor sensitive to temperature.Moreover, TPEE with shore hardness D40 or D45 has been grafted by a graft polymer. with the analysis of the thermal decomposition temperature and the melt absorption peak, and the results show that the structure of TPEE is changed by the graft polymer, in addition, the thermal decomposition temperature and the melting absorption peaks is tend to high temperature. Meanwhile, the melt folw rate of TPEE with Shore hardness D45 can drop to 5g/10min. when the content of the graft agent is 6phr, the compression set is lowest, tensile strength is highest, the damping factor tanθand the range of damping temperature of TPEE with shore hardness D40 is 0.24 and 120℃respectively, in contrast, the corresponding value of TPEE with shore hardness D45 is 0.21 and 160℃, the range of damping temperature increases 40℃. For foamed TPEE with shore hardness D45, the rate of the closed cell is highest, and the cell structure is neat.Finally, the faomed TPEE have been prepared by the different extrusion die with flow-resisted set. And the results show that surface topography and section structure of the foamed TPEE are worse with the raise of die thickness. When the die thickness is 10mm, the surface topography is the most leveling, and also the uniform cell can be obtained.
Anion exchange membrane direct methanol fuel cell (AEM-DMFC) uses anion exchange membrane as polyelectrolyte. In alkaline media, the methanol oxidative rate gets much faster. Moreover, the direction of the carriers OH” anion motion opposes that of the methanol flux through the membrane leading to an intrinsic reduction in methanol permeability. Therefore, AEM-DMFC can greatly overcome the problem of DMFC.The main chain of poly(vinylbenzyl chloride) (PVBCl) is styrene structure with chloromethyl in 3-/4- of benzene ring. Anion exchange membranes can be prepared through PVBCl directly reacting with quaternary aminating agents. In that case, the chloromethylation process can be avoided. In this study, PVBCl anion exchange membranes were prepared. The processing technologies and properties were studied as well.The preparation route of PVBCl anion exchange membranes was designed in this work. Isoamyl acetate was used as solvent to prepare polymer solution with the concentration of 100～200mg/mL. Diamine compounds were used as quaternary aminating agents to introduce the quaternary amine group and crosslinking structure into PVBCl after the crosslinking reaction between PVBCl and diamine. By phase separation, PVBCl anion exchange membranes were prepared through polymer solution extending in the glass plate.Comparison of different amount of the same crosslinking agent, it was shown that with the increasing of the amount, the toughness of membranes got higher, water content decreasd and ion exchange capacity increased. Comparison of crosslinking agents with different length of methylene, it could be seen that under the same amount, with the increasing of the length of methylene, the toughness of membranes got higher, water content increased, and yet ion exchange capacity changed very little.Using real-time FTIR tracking the crosslinking reaction course between PVBCl and TMHDA, the effects of reaction time and temperature on degree of crosslinking were studied. The experimental results demonstrated that the degree of crosslinking increased rapidly at the beginning, and then changed slowly to a constant value with the addition of reaction time. It also showed that higher temperature was conducive to the conduct of the crosslinking reaction which was an endothermic process. In addition, the reaction kinetics was studied through FTIR spectral data treatment. The kinetics results showed that the reaction order (n) equaled to 4, and the reaction activation energy (Ea) was about 97.2KJ·mol-1·K-1.Using TMHDA with the longest length of methylene in the experiment as crosslinking agent, it appeared that membranes cracked with the increasing of the amount of TMHDA. Under the low amount, the ion exchange capacity of membranes was very little. Ion exchange capacity could be improved by using mixed crosslinking agents or adding other quaternary aminating agents such as triethylamine.Due to styrene rigid structure of PVBCl main chain, PVBCl anion exchange membranes appeared obviously brittle. Thus, blending SEBS with chloromethylation as plasticizer into PVBCl was tried to prepare membranes. With the addition of SEBS, the toughness of membranes got much higher. And as the content of SEBS increased, the toughness of blend membranes gradually enhanced. Under the effect of external electric field, it was achieved that OH- transmitted through membranes. Compared with the Nafion membranes, blending membranes have lower methanol permeability.