Novel sandwich structured glass fiber Cloth/Poly(ethylene oxide)-MXene composite electrolyte

Recently,poly(ethylene oxide)(PEO)-based solid polymer electrolytes have been attracting great attention,and efforts are currently underway to develop PEO-based composite electrolytes for next generation high performance all-solid-state lithium metal batteries.In this article,a novel sandwich structured solid-state PEO composite electrolyte is developed for high performance all-solid-state lithium metal batteries.The PEO-based composite electrolyte is fabricated by hot-pressing PEO,LiTFSI and Ti_(3)C_(2)T_(x) MXene nanosheets into glass fiber cloth(GFC).The as-prepared GFC@PEO-MXene electrolyte shows high mechanical properties,good electrochemical stability,and high lithium-ion migration number,which indicates an obvious synergistic effect from the microscale GFC and the nanoscale MXene.Such as,the GFC@PEO-1 wt%MXene electrolyte shows a high tensile strength of 43.43 MPa and an impressive Young's modulus of 496 MPa,which are increased by 1205%and 6048%over those of PEO.Meanwhile,the ionic conductivity of GFC@PEO-1 wt%MXene at 60℃ reaches 5.01×10^(-2) S m^(-1),which is increased by around 200%compared with that of GFC@PEO electrolyte.In addition,the Li/Li symmetric battery based on GFC@PEO-1 wt%MXene electrolyte shows an excellent cycling stability over 800 h(0.3 mA cm^(-2),0.3 mAh cm^(-2)),which is obviously longer than that based on PEO and GFC@PEO electrolytes due to the better compatibility of GFC@PEO-1 wt%MXene electrolyte with Li anode.Furthermore,the solid-state Li/LiFePO_(4) battery with GFC@PEO-1 wt%MXene as electrolyte demonstrates a high capacity of 110.2–166.1 mAh g^(-1) in a wide temperature range of 25–60C,and an excellent capacity retention rate.The developed sandwich structured GFC@PEO-1 wt%MXene electrolyte with the excellent overall performance is promising for next generation high performance all-solid-state lithium metal batteries.

FOURIER TRANSFORM INFRARED STUDIES OF POLY (ETHYLENE TEREPHTHALATE) FILM IN THE GLASS TRANSITION REGION

Three specimens from a solution-cast poly （ethylene terephthalate） （PET） film, one being liquid-N2 quenched from 92℃（Q）, one being slowly cooled from 92℃（SC） and one being quenched and sub-Tg annealed at 67℃（AN）, have been studied by specimen difference spectra Q-SC and AN-Q and temperature difference spectra T-70 and T2-T1 for every 2℃steps on heating to 90℃at 2℃/min. SC and AN showed more gauche conformers than Q. That means that the PET chain has more trans conformers at higher temperatures and some of these are frozen during quenching through Tg. A band at 1340 cm-1 has been found to be complex containing overlapping bands reflecting trans in crystalline regions and trans in amorphous regions. The temperature difference spectra on heating through Tg showed that the spectral changes in Q are gradual while a rather abrupt change occurs in AN at 80—82℃for the bands at 1340, 1042 and 1020 cm-1. No new conformational structure or new vibrational mode is involved. A kind of locking mechanism is suggested which hinders the molecular vibrational changes in AN below Tg until a sudden release occurs at Tg. These locking sites can be nothing else than sites of tighter local packing of chain segments. Consequently it is believed that inter-chain van der Waals attraction energy plays a dominating role in the volume relaxation and sub-Tg annealing of quenched amorphous polymers.

Studies on the Simultaneous Synthesis of Dimethyl Carbonate and Poly(ethylene terephthalate): I. Catalytic Activity of Metal Acetate in Transesterification of Ethylene Carbonate with Dimethyl Terephthalate

A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithium acetate dihydrate showed highest catalytic activity with 47.9% yield of dimethyl carbonate. This method was a green chemical process.

Flame Retardancy and Thermal Property of Poly (ethylene terephthalate)/Modified Cyclotriphosphazene Composites

In this study,hexachlorocyclotriphosphazene( HCCP)modified by boric acid and 3-aminopropyltriethoxysilane( KH-550)in solvent diglyme( FR-HCCP) was used as the flame retardant for poly( ethylene terephthalate)( PET) composites. The flame retardancy and thermal property of pure PET and flame-retarded PET composites were mainly investigated. The flame retardancy was investigated by limited oxygen index( LOI) and UL-94 vertical burning test. The results showed that the composites could achieved an increased UL-94 V-0 rating and LOI value 30. 2, when the content of FR-HCCP was just 1%. The pyrolysis-gas chromatography-mass spectrometry( Py-GC / MS) study demonstrated that introducing FR-HCCP into PET would prevent the polymer pyrolysis during heating. TGA analysis showed that the addition of FR-HCCP could improve the char formation of the system. Roman spectra showed the order degree of residue was increasing by adding the additive. The morphology and the chemical structure of the charred residue were detected by SEMand FTIR,respectively. Results demonstrated that a good barrier was formed by the char of the composite,which protected the inside of the composite during burning.

THERMALLY STIMULATED SHAPE MEMORY BEHAVIOR OF(ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE)SEGMENTED COPOLYMER

The thermally stimulated shape memory behavior of ethylene oxide-butylene terephthalate (EOBT) segmentedcopolymers with different soft segment molecular weight and hard segment content was investigated. The deformationrecovery ratio R_f of the EOBT samples increases with the soft segment molecular weight and the hard segment weightcontent, while the average overall deformation recovery speed V_r increases with the hard segment content. The temperatureof maximum deformation recovery speed (T_M) is determined by the melting temperature of the soft segment crystals and thestability of the crystallized hard segment domains.

Synthesis and characterization of copolymers of poly(m-xylylene adipamide) and poly(ethylene terephthalate) oligomers by melt copolycondensation

Poly(m-xylylene adipamide)/poly(ethylene terephthalate)(MXD6/PET) copolymers are synthesized by melt copolycondensation with 1–5 wt% low molecular weight PET oligomers into the MXD6 oligomers at 260 °C.FR-IR and1 H NMR analysis results indicate that the interchange reaction has occurred between MXD6 oligomers and PET oligomers. The thermal behavior of copolymers shows that the melting temperature of MXD6/PET copolymers decreases with the increasing of amount of PET oligomers, while the crystallization temperature accordingly increases. And the equilibrium temperature Tm0 is evaluated to be 251.8 °C for the copolymers with5 wt% PET oligomer adding, which is very close to that of neat MXD6. The tensile and impact strength of MXD6/PET copolymers are significantly improved than that of pure MXD6 by mechanical properties test, and the microfibril structure in the impact fracture sample's surface reveals the feature of ductile fracture.

Simultaneous Synthesis of Dimethyl Carbonate and Poly（ethylene terephthalate） Using Alkali Metals as Catalysts

Dimethyl 碳酸盐(直接数字控制) 并且(乙烯 terephthalate ) 被乙烯碳酸盐(EC ) 的 transesterification 同时 poly 在这篇论文与暗淡乙醇 terephthalate (DMT ) 综合。没有有毒的物质，这反应是一个优秀绿化学过程。各种各样的碱金属被用作催化剂。结果证明碱金属在某个程度举办了催化活动。反应状况的效果也被学习。当反应在下列条件下面被执行时：反应温度 250 ° C，到 DMT 3:1 的 EC 的臼齿的比率，反应时间 3h，和催化剂总计 0.004 (到 DMT 的臼齿的比率) ，直接数字控制的收益是 68.9% 。

Characterization and Properties of Electroless Nickel Plated Poly (ethylene terephthalate) Nonwoven Fabric Enhanced by Dielectric Barrier Discharge Plasma Pretreatment

In order to develop a more economical pretreatment method for electroless nickelplating,a dielectric barrier discharge (DBD) plasma at atmospheric pressure was used to improvethe hydrophilicity and adhesion of poly (ethylene terephthalate) (PET) nonwoven fabric.The properties of the PET nonwoven fabric including its liquid absorptive capacity (W_A),agingbehavior,surface chemical composition,morphology of the surface,adhesion strength,surfaceelectrical resistivity and electromagnetic interference (EMI)- shielding effectiveness (SE) were studied.The liquid absorptive capacity (W_A) increased due to the incorporation of oxygen-containingand nitrogen-containing functional groups on the surface of PET nonwoven fabric after DBD air-plasmatreatment.The surface morphology of the nonwoven fibers became rougher after plasmatreatment.Therefore,the surface was more prone to absorb tin sensitizer and palladium catalystto form an active layer for the deposition of electroless nickel.SEM and X-ray diffraction (XRD)measurements indicated that a uniform coating of nickel was formed on the PET nonwoven fabric.The average EMI-SE of Ni-plating of PET nonwoven fabric maintained a relatively stable value(38.2 dB to 37.3 dB) in a frequency range of 50 MHz to 1500 MHz.It is concluded that DBDis feasible for pretreatment of nonwoven fabric for electroless nickel plating to prepare functionalmaterial with good EMI-SE properties.

In-situ Polymerization-modification Process and Foaming of Poly（ethylene terephthalate）

Most of traditional linear poly(ethylene terephthalate)(PET)resins of relatively low molecular mass and narrow molecular mass distribution have low melt strength at foaming temperatures,which are not enough to support and keep cells.An in-situ polymerization-modification process with esterification and polycondensation stages was performed in a 2 L batch stirred reactor using pyromellitic dianhydride(PMDA)or pentaerythritol(PENTA)as modifying monomers to obtain PETs with high melt strength.The influence of amounts of modifying monomers on the properties of modified PET was investigated.It was found that the selected modifying monomers could effectively introduce branched structures into the modified PETs and improve their melt strength.With increasing the amount of the modifying monomer,the melt strength of the modified PET increased.But when the amount of PENTA reached 0.35%or PMDA reached 0.9%,crosslinking phenomenon was observed in the modified PET.Supercritical carbon dioxide(ScCO2)was employed as physical foaming agent to evaluate the foaming ability of modified PETs.The modified PETs had good foaming properties at 14 MPa of CO2pressure with foaming temperature ranging from 265°C to 280°C.SEM micrographs demonstrated that both modified PET foams had homogeneous cellular structures,with cell diameter ranging from 35μm to 49μm for PENTA modified PETs and38μm to 57μm for PMDA modified ones.Correspondingly,the cell density had a range of 3.5×107cells·cm 3to 7×106cells·cm 3for the former and 2.8×107cells·cm 3to 5.8×106cells·cm 3for the latter.

Isothermal Crystallization Behavior of Poly (ethylene terephthalate)/Carbon Black Masterbatch

Poly(ethylene terephthalate) (PET)/carbon black (CB) masterbatch was prepared by melt blending using a separate feeding technique and its homogeneous dispersion morphology was confirmed by transmission electron microscope (TEM). The Avrami and Hoffman-Lauritzen secondary nucleation theories were employed to analyze the effect of high CB content on crystallization kinetics of PET, providing theoretical support for the development of masterbatch with high content of functional components. The Avrami exponents,average values of n,for PET and PET/CB masterbatch are both greater than 3, which indicates three-dimensional growth of crystals. In addition,no significant evidence for regime transition of PET is found applying Hoffman-Lauritzen secondary nucleation theory,though such observations have been reported previously in the literature. Furthermore,appropriate U* value for PET is determined to be 12 800 J/mol. For PET/CB masterbatch,a transition from regime I to regime II around 225℃ is observed with appropriate U* value (12 800 J/mol) . This phenomenon is consistent with a transition point in plot of G versus Tc . The fold surface free energy σe (100. 3 mJ/m 2) of PET is much greater than that of PET/CB masterbatch (48. 3 mJ/m 2) ,which indicates heterogeneous nucleation effect of CB particles.

High-efficiency acetaldehyde removal during solid-state polycondensation of poly(ethylene terephthalate) assisted by supercritical carbon dioxide

The concentration of acetaldehyde(AA) is the main quality index of poly(ethylene terephthalate)(PET) used in food and drink packaging.A new method for AA removal has been developed by using supercritical carbon dioxide(sc CO2) during the solid-state polycondensation of PET.The influence factors of AA removal including the temperature,pressure,reaction time and the size of pre-polymer particles are systematically studied in this work.The results indicate that it is a highly efficient way to obtain high molecular weight PET with relative low concentration of AA.Correspondingly,the polymerization degree of PET could increase from 27.9 to 85.6 while the concentration of AA reduces from 0.229 × 10^(-6) to 0.055 × 10^(-6) under the optimal operation conditions of 230 °C,8 MPa and size of 0.30–0.45 mm.Thermodynamic performance tests show the increasing extent of PET crystallinity due to the fact that the plasticization of sc CO_2 is not obvious with extended reaction time,therefore the increasing crystallinity has no significant influence on AA removal.SEM observations reveal that the effects of sc CO_(2-) induced plasticization and swelling on PET increase significantly with the decrease of prepolymer size,and the surface of PET becomes more loose and porous in favor of the AA removal.

Stannous-acetylacetonate:A new catalyst for poly(trimethylene terephthalate) synthesis

Stannous-acetylacetonate was prepared efficiently and characterized by 1H NMR and FT-IR. Its catalytic activity for poly(trimethylene terephthalate) (PTT) synthesis was investigated. By this catalyst, the degree of esterification of pure terephthalic acid was up to 91.7% after reaction at 260°C for 2 h, while the intrinsic viscosity and content of ter- minal carboxyl groups of the corresponding PTT polymerized at 260°C, 60 Pa for 2 h was 0.8816 dL/g and 17 mol/t, respectively. Stannous-acetylacetonate was more active and promising than tetrabutyl titanate and stannous octoate for PTT synthesis.

Thermal degradation and isothermal crystalline behavior of poly(trimethylene terephthalate)

(整齐的乙烯 terephthalate )(PTT ) Poly 是优秀纤维材料。它的热降级和等温的水晶的行为在用 thermogravimetric 分析(TGA ) 调查的这研究， thermogravimetric analysis&#x2013； Fourier 变换红外线的光谱学(TGA&#x2013； FTIR ) 分析，微分扫描热量测定(DSC ) 和 X 光检查衍射(XRD ) 。PTT 的热降级机制跟随 Mclafferty 重新整理原则。有 0.74 dl/g 的内在的粘性(IV ) 的 PTT 在 190 &#xb0 有大约 55% 的最大的 crystallinity； C 一致地由 DSC 和 XRD 大小示威了。

Flame Retardant Finishing of Poly(ethylene terephthalate) Fabric with a Carbon Source Containing DOPO Derivative

9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide( DOPO)-based flame retardant( DOPO-DOPC) which contains carbon source was used to improve the flame retardancy of poly( ethylene terephthalate)( PET) fabrics. The prepared DOPODOPC dispersion was applied onto PET fabrics via two kinds of processes,thermosol process and exhaustion process,and in the later using it alone or together with disperse dyes. The flame retardancy of PET fabrics was determined by limiting oxygen index( LOI) and vertical burning test. The results showed that DOPODOPC could obviously improve the flame retardancy of PET fabrics.The PET fabric treated by 60 g/L DOPO-DOPC dispersion via exhaustion process achieved an LOI value of 32. 3%,for example.The flame retardancy and dyeing performances showed that DOPODOPC dispersion could be used together with a part of disperse dyes in one bath. The thermal stability of DOPO-DOPC and the treated PET fabrics were investigated by thermogravimetric analysis( TGA). And the flame retardant mechanism of DOPO-DOPC treated PET fabrics was further investigated by pyrolysis-gas chromatography/mass spectrometry( Py-GC/MS), Fourier transform infrared spectroscopy( FTIR) and scanning electron microscopy( SEM).

Enzymatic Modification of Poly (ethylene terephthalate) Fiber with Lipase from Aspergillus oryzae

Lipase preparation from Aspergillus oryzae could act on ester bonds on the surface of poly (ethylene terephthalate) fibers and a possible hydrolytic product mono (2-hydroxyethyl) terephthalate was released.After the iipase modification,there were more carboxyl groups on the treated poly (ethylene terephthalate) fabric surface that resulted in binding with more cationic dyes.Increased hydrophilicity and antistatic ability of poly (ethylene terephthalate) samples were found based on moisture regain,water contact angle and static half decay time.

KINETICS OF NON-ISOTHERMAL CRYSTALLIZATION OF POLY (ETHYLENE TEREPHTHALATE) MODIFIED BY POLY (ETHYLENE GLYCOL)

The non-isothermal crystallization kinetics of poly（ethylene terephthalate） （PET） modified by poly （ethlene glycol） （PEG） were determined by DSC. The dual linear regression method was used to evaluate the relationship between the reciprocal of t 1/2 （ the half life of crystallization） and the appropriate temperature variable. The parameters such as the activation energy （Ed） for transport, the equilibrium melting temperature （Tm0）,the nucleation parameter （ψ）,themaximum crystallization temperature (Te, max), and the kinetic crystallizability （G） for the copolyesters were obtained. The influence of the PEG content in PET chains on the parameters characterizing crystallization kinetics and crystallization thermodynamics was discussed.

CRYSTALLIZATION BEHAVIOR OF PURE AND ADDITIVE-CONTAINING POLY (ETHYLENE TEREPHTHALATE)

The isothermal crystallization of poly (ethylene terephthalate ) (PET),which is free of catalyst, stabilizer, oligomer and diethylene glycol (DEG), was studied by DSC. The crystallization behaviour of pure PET is different from commercial PET and a reasonable explanation is presented. The influences of catalyst, stabilizer, oligomer and DEG on the crystallization of pure PET were examined. It is shown that catalyst (Manganese acetate)and stabilizer (Triphenyl phosphite) result in an increase of the crystallization rate of PET; on the contrary, DEG and oligomer (cyclotetramer) result in a reduction of the crystallization rate. When catalyst and stabilizer coexist together, both of them promote the crystallization at lower temperature ,only a smaller effect was found at higher temperature, it is evident that metal phosphite is formed between the catalyst and stabilizer at higher temperature.

TRANSESTERIFICATION OF POLY(ETHYLENE TEREPHTHALATE) WITH POLY(ε-CAPROLACTONE)

Transesterification of poly(ethylene terephthalate) (PET) with poly(ε-caprolactone) (PCL) was investigated bymeans of NMR spectroscopy, extraction experiments, differential scanning calorimetry (DSC) and phase contrast microscopy(PCM). The ~1H-NMR results show that transesterification takes place in the melt blends and leads to the formation of thePET-PCL copolyester with a chemical structure similar to ethylene terephthalate-ε-caprolactonc copolycster (TCL)synthesized directly from monomers. However, even in the blend that has been transesterified for 8 h, the random PET-PCLcopolyester, PET-PCL copolyester with long PET or long PCL segments and the unreacted PET and PCL homopolymersmay coexist. Due to the low mobility of PET and PCL chains and the high viscosity of the two macromolecules, thetransesterification proceeds with difficulty. Furthermore, PET is incompatible with PCL, the transesterification can onlyoccur at the interface or in the interfacial region between two phases, and finally the reaction can only reach a localequilibrium. These results indicate that in fact the transesterification in the melt blend between two incompatiblehomopolymers could not lead to the formation of completely random or typical block copolyesters.

EFFECT 0F INTERFACIAL ADHESION ON CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY (ETHYLENE TEREPHTHALATE)/GLASS BEAD COMPOSITES

The interfacial adhesion between poly (ethylene terephthalate) (PET) and glass beadwas investigated by scanning electron microscope and parallel-plate rheometer. Effect ofinterfacial adhesion on the crystallization and mechenical properties of PET/glass beadcomposites was also studied by differential scanning calorimeter and mechanical testers.The results obtained indicate that the glass bead has a heterogeneous nucleation effecton the PET crystallization. Although better interfacial adhesion is advantageous to theincrease of the tensile strength of the composite, yet it is unfavorable to the crystallizationof PET. It should be pointed out that the crystallization rate of filled PET is always higherthan that of pure PET, regardless of the state of interfacial adhesion.

RECOVERY OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)FILM UNIAXIALLY DRAWN JUST BELOW THE GLASS TRANSITION TEMPERATURE

Isothermal recovery in the macroscopic length of homogeneously deformed specimens of amorphous poly（ethyleneterephthalate） （PET） film sample uniaxially drawn at 69℃ to the draw ratios λ0=1.26～2.20 were studied at temperaturesaround the glass transition temperature （Tg = 73℃）. Experimental results indicate that the length recovery took place in twodistinct steps: a fast first step （fast relaxation） followed by a slow second step （slow relaxation）. The relaxation processeswere accompanied by the reversion of trans-conformers (1340 cm-1) to gauche, and the dichroic function of the 1340 cm-1band characterizing the segmental orientation along the chain direction decreased to a very low value at the end of the fastrelaxation. This fact led us to assign the fast relaxation as the segmental orientation while the slow relaxation as relaxation ofthe global chain orientation. It was found that the slow relaxation follows a single exponential function, with relaxation timesstrongly dependent on the temperature resembling the glass transition process. The fast relaxation does not follow a singleexponential decay, presumably a distribution of relaxation times is involved.