聚乙烯基三苯乙炔基硅烷的热分解动力学

为研究聚乙烯基三苯乙炔基硅烷树脂的热分解机理,利用TG-DTG技术探讨了聚乙烯基三苯乙炔基硅烷树脂的非等温热分解过程.借助非模型拟合法和模型拟合法分析了聚乙烯基三苯乙炔基硅烷树脂(PVTPES)的热分解行为,建立了动力学函数,得到了聚乙烯基三苯乙炔基硅烷树脂的热分解反应机理.结果表明,6种热分析方法计算得到PVTPES的热分解活化能(E)在240 k J/mol左右,指前因子lg A=15.51,机理符合三维(3D)扩散控制机理.聚合物PVTPES的热分解过程分析进一步证实芳炔单体的热聚合为环三聚反应.     

聚二苯基二苯乙炔基硅烷树脂的制备与非等温热分解

以溴乙烷、二苯基二氯硅烷、苯乙炔为原料,通过格利雅反应合成二苯基二苯乙炔基硅烷单体(DPDPES),利用FTIR和~1H-NMR对单体分子结构进行表征。采用热聚合方法制备了聚二苯基二苯乙炔基硅烷树脂(PDPDPES),借助TG-DTG技术研究了PDPDPES的非等温热分解过程,运用模型法对热分解过程进行分析,建立动力学函数,推导出热分解机理,并应用非模型法对热分解机理函数进行验证。实验结果表明,6种分析方法得到的热分解活化能E_a=245.37kJ/mol,指前因子lgA=13.78s~(-1),机理函数式:f(α)=10/23·(1-α)·[-ln(1-α)]~(-1.3);g(α)=[-ln(1-α)]~(2.3)。     

聚乙烯基三苯乙炔基硅烷的制备及热性能分析

为研究聚乙烯基三苯乙炔基硅烷树脂的热性能,以苯乙炔和乙烯基三氯硅烷为原料,运用格利雅反应合成了乙烯基三苯乙炔基硅烷单体,并通过红外(FT-IR)、核磁(1H-NMR,13C-NMR,29Si-NMR)证实了合成产物.以此单体为原料,通过热聚合法制备了聚乙烯基三苯乙炔基硅烷树脂,并采用TGA-DTG研究该聚合物的热分解动力学,计算了相应动力学参数.结果表明:该树脂的热分解温度(Td5%)在550℃左右,800℃时聚合物的残炭率约80%;用Kissinger法和Ozawa法求得的聚合物热分解活化能分别为266.55和236.89 k J/mol;用Crane法求得聚合物的热分解反应级数为0.93,近似为一级反应.     

双(N-间乙炔基苯基邻苯二甲酰亚胺)醚改性甲基二苯乙炔基硅烷

甲基二苯乙炔基硅烷 (MDPES) 聚合后具有耐高温、低介电损耗等优异性能,但力学性能低。采用双 (N-间乙炔基苯基邻苯二甲酰亚胺) 醚 (DAIE) 添加到MDPES中进行共聚改性。通过二者不同质量配比的共聚反应发现,当M_DAIE /M_MDPES=4∶5时,共聚后改性效果较好,在氮气中的T_d5 (质量损失5% 时的温度) 为467℃,800℃时质量保留率为82.7%,所制备的复合材料在常温下弯曲强度达到274MPa;高温弯曲强度保留率为88.5%。在频率为1MHz时介电常数为4.18,介电损耗角正切tanδ为2.5×10-3。      

聚甲基苯基二苯乙炔基硅烷树脂的热稳定性与介电性能

为研究聚甲基苯基二苯乙炔基硅烷树脂的热稳定性与介电性能,以甲基苯基二氯硅烷、苯乙炔、镁条为原料,通过Grignard反应制备甲基苯基二苯乙炔基硅烷(MPDPES),再通过热聚合法制备聚甲基苯基二苯乙炔基硅烷树脂(PMPDPES).采用傅里叶变换红外光谱(FTIR)和核磁共振波谱(1 H-NMR、13 C-NMR和29 ...     

苯乙炔基封端聚酰亚胺树脂的固化动力学研究

采用非等温差示扫描量热法(DSC)研究了两种苯乙炔基封端型聚酰亚胺树脂固化动力学过程,分析了不同升温速率下,两体系的特征固化温度,反应热及反应速率与温度的关系。运用Kissinger法和Melak法进行数据处理。结果表明:(1)苯乙炔封端型聚酰亚胺树脂的固化过程符合n级固化反应方程,建立的固化反应方程较好地描述了其固化过程,且与实验数据拟合结果较好。(2)两树脂体系相比,分子链柔性较大的聚酰亚胺树脂特征固化温度较低,固化温区较宽,固化反应活化能较低,且反应级数较大。     

炔丙基改性酚醛树脂聚合物的非等温热分解动力学

运用TG-DTG技术研究了炔丙基改性酚醛树脂聚合物的非等温热分解过程,通过Kissinger法和FWO法获得聚合物分解的动力学参数,利用模型拟合法推测该聚合物的热分解机理,并用非模型拟合法对机理进行了验证。实验结果表明,该聚合物的Td5分解温度在390℃左右,800℃时残炭率在30%左右。7种动力学分析方法显示聚合物的热分解活化能为92.95 k J/mol,指前因子lgA=4.71 s-1,n=2,分解符合二维扩散机理,对应的机理微分函数f(α)=(1-α)1/2[1-(1-α)1/2]-1积分函数g(α)=[1-(1-α)1/2]2聚合物的热分解反应方程为dα/dT=(5.14×104/β)exp(-92.95×103/RT)×(1-α)1/2×[1-(1-α)1/2]-1     

聚甲基硅次乙炔基硅烷等温预处理过程的研究

采用差示扫描量热仪和傅立叶红外光谱对聚甲基硅次乙炔基硅烷(MSE)等温(160、170、180℃)预处理过程进行了研究.结果表明:IVISE等温处理过程中发生氢硅化反应,反应程度约为33%;相对反应程度达到95%时,所需时间分别为173(160℃)、93(170℃)和48(180℃)min;预处理时间t与处理温度T之间满足关系t(T)/t(T 10K)=2:1.     

聚苯硫醚非等温热分解动力学研究

采用非等温法测定和对比了国产及进口聚苯硫醚(PPS)树脂的热失重动力学行为。运用动力学分析软件计算出动力学参数(活化能Ea、指前因子Z和反应级数n),运用动力学方程估算出两种PPS切片的热分解转化率α、温度T以及时间t之间的关系。结果表明,国产PPS切片的热稳定性略优于进口PPS切片。在低于350℃时,两种切片均十分稳定,因此,在通常的纺丝条件下(300℃左右)发生热分解的可能性均很小。如果在更高的温度范围内加工PPS树脂或使用PPS的产品,热分解的影响则不容忽视。     

新型含杂萘联苯聚醚砜类嵌段共聚物的合成与性能研究

采用连续缩聚法合成氯端基聚醚砜齐聚物,然后与杂萘联苯构成的类双酚合成的羟端基齐聚物进行缩聚反应,合成了新型PPES-PES嵌段共聚物.用IR、DSC、TGA、X-WAXD等方法对聚合物进行了表征,并研究了聚合物的溶解性能.结果表明该嵌段共聚物具有较高的玻璃化转变温度,较好的热稳定性和良好的溶解性能,为非结晶型聚合物,并可浇铸得到透明、韧性高的薄膜.实验还发现聚醚砜组分含量变化对共聚物的热性能影响很大,对杂萘联苯聚醚砜改性效果明显.     

新型可降解聚硅基酯的合成及性质研究

主链中含有不稳定的硅酯键的聚硅基酯是一种新型的可降解聚合物.合成并研究了新型聚硅基酯即聚(己二酸四甲基二硅氧烷基硅基酯):首次利用熔融缩聚法使己二酸与1,1,3,3-四甲基二硅氧烷为单体合成了聚硅基酯,并用1H-NMR对该聚合物进行了结构表征,利用差示扫描量热(DSC)、热重分析(TGA)对其热力学性质进行了研究,利用凝胶渗透色谱(GPC)就分子量分布及降解性质进行了研究.     

Synthesis, characterization and fluorescence quenching of poly(fluorene-alt-enylenevinylene)s

Two poly(fluorine-alt-phenylenevinylene)s fluorescent conjugated polymers, poly(9,9-dioctylfluorene-alt-phenylenevinylene) (PFO/PPV1) and poly (fluorene-alt-2,5-dioctoxyphenylenevinylene) (PFO/PPV2), were obtained through a Heck polycondensation. The structures of the obtained polymers were characterized by FT-IR, ¹H-NMR and GPC. The thermal stabilities of the polymers were evaluated by TGA. The photophysical properties were studied by UV and photoluminescence (PL) spectroscopy both in solution and film. Their applications in the detection of nitro compounds were researched, and the results show high fluorescence quenching sensitivity of PFO/PPV1 towards nitro compounds such as 2,4-dinitrotoluene (DNT) and 4-nitrotoluene (p-NT) in solution and thin film.     

Crystal morphology,mechanical property and non-isothermal crystallization kinetics of poly(trimethylene terephthalate)/maleinized poly(ethylene-octene) copolymer binary blends

The crystal morphology, impact strength and nonisothermal crystallization kinetics of poly(trimethylene terephthalate)/maleinized poly(ethylene-octene) (PTT/PEO-MA) copolymer blends were studied by using the polarized optical microscopy, impact tester and differential scanning calorimetry (DSC). Avrami theory modified by Jeziorny, Ozawa and Mo theories were used to study the non-isothermal crystallization kinetics of the blends, respectively. The results suggest that these methods are suitable for analyzing the crystallization kinetics of the PTT/PEO-MA blends. The PEO-MA component, serving as a nucleation agent in blends, can increase the start crystallization temperatures and accelerate the crystallization rate of the blends. The crystal dimensions are predominantly three-dimensional growths, judged from the Avrami exponent n and the Ozawa exponent m, but the spherulites in blends are much smaller than those in pure PTT. The crystallization active energy suggests that the PEO-MA component can make the PTT component easy to crystallize in blends. The blend has the highest Izod impact strength as PEO-MA content is 3wt.%. Considering both the crystallization kinetic analyses results and the crystal morphology of the blends, the modified Avrami method is believed to be the most useful in reflecting the crystallization of the blends.     

Drift in the resistance of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) printed films during thermal cycling

We report on the investigation of the suitability of printed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films for temperature sensing devices. Gravure printing with the advantage of low cost production was used to prepare thin films of PEDOT:PSS on a flexible foil substrate. The electrical resistance was studied during thermal cycling and exposure to elevated constant temperatures. A drift of the resistance which depends on time, temperature and sample makes the usage as simple temperature sensors not possible. However, a closer look on the drift of relative resistances reveals that integrated temperature-time-profiles can be measured, which might be interesting in connection with monitoring of conditions of storing and transport of sensitive goods.     

聚-1,3,4-噁二唑纤维研究进展

介绍了聚-1,3,4-噁二唑(POD)的合成、改性、纺丝成形、后处理及耐老化等方面的研究进展。详述了采用一步法三阶段合成POD,并通过引入间苯二甲酸和对苯二甲酸进行共聚改性,得到的POD纤维在亲水性、抗静电性、染色性能等方面得到了改善;探讨了凝固浴条件对POD纤维结构与性能的影响,阐述了POD纤维的老化降解及防护问题。