PTT/PC合金的动态力学行为研究

研究了聚对苯二甲酸丙二酯(PTT)/聚碳酸酯(PC)合金的动态力学行为,探讨了增容剂环氧树脂(EP)和三元乙丙橡胶接枝甲基丙烯酸缩水甘油酯(EPDM-g-GMA)对合金动态力学行为的影响.结果表明,未增容的PTT/PC合金显示两个独立的、随配比而稍变化的玻璃化转变松弛峰Tg(PTT)和Tg(PC);PTT对PC玻璃化转变时链段运动的影响远大于PC对PTT玻璃化转变时链段运动的影响;PC能显著提高PTT的模量和热变形温度.EP强烈地影响了PTT/PC合金的松弛行为,使Tg(PTT)和Tg(PC)相互靠近,且损耗强度显著增加;当PC质量分数为30％且EP用量为2.7份时,PTT/PC合金热变形温度明显提高,高弹态平台消失,材料高温刚性增加.EPDM-g-GMA对PTT/PC合金松弛行为的影响不如EP,当EPDM-g-GMA的用量为5份以下时,仅使Tg(PTT)和Tg(PC)略有靠近,但损耗强度无明显变化,当其用量为10份时,Tg(PTT)和Tg(PC)在宽广温度区间内融合为一,损耗强度显著增加;EPDM-g-GMA使PTT/PC的玻璃态模量和高弹态模量均显著降低,但对热变形温度影响不大.     

以聚酯多元醇为基的聚氨酯弹性体的动态力学性能研究

合成了以聚酯多元醇为基的聚氨酯弹性体(PUE),研究了聚酯多元醇结构及相对分子质量、扩链剂类型及用量等因素对聚氨酯弹性体的动态力学性能的影响。结果表明:以相对分子质量为2000及3000的聚酯多元醇制得的PUE中存在明显的相分离;当扩链剂中带有苯环结构时,PUE的玻璃化转变温度(Tg)升高,储能模量增加,阻尼因子下降;PUE的Tg及储能模量随着扩链剂L-MOCA用量的增加线性升高,阻尼因子线性下降。     

形状记忆CTBN/CE嵌段共聚物的制备与性能

氰酸酯(CE)树脂的刚性结构致使其本身不具备形状记忆行为,而将含有柔性链段的端羧基液体丁腈橡胶(CTBN)改性CE并形成共聚物后,共聚物体系则具备较好地形状记忆行为。通过力学性能测试、DMA分析和形状记忆行为研究对CTBN/CE共聚物进行了表征,结果表明:随CTBN含量的增加,共聚物的弯曲强度由83 MPa降至48 MPa,且储能模量和玻璃化转变温度(Tg)也逐渐减小,从而实现了共聚物的Tg可控性。形状记忆测试表明随CTBN含量的增加,共聚物的形状记忆性能逐渐提高,回复时间由532 s缩短至90 s。     

1,3–PBO扩链废旧ABS塑料的性能表征

以2,2′–(1,3–亚苯基)–二噁唑啉(1,3–PBO)为扩链剂,在双螺杆挤出机中对废旧丙烯腈–丁二烯–苯乙烯塑料(r ABS)进行熔融扩链,并研究了1,3–PBO含量变化对r ABS的相对分子质量、力学性能、动态力学性能和断面形貌特征的影响。结果表明,与r ABS相比:扩链产物的相对分子质量大幅提高,数均相对分子质量达到20 885;产物的力学性能显著提高,缺口冲击强度提高到r ABS的近三倍;产物的储能模量、损耗模量明显增加,聚丁二烯(PB)相的玻璃化转变温度(Tg)降低,苯乙烯/丙烯腈共聚物(SAN)相的Tg升高;产物断面的形貌变得粗糙,相界面得到修复。     

聚醚型聚氨酯弹性体的合成及其动态力学行为

采用两步合成法,以4,4′-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段,相对分子质量分别为1000、2000、4000的聚氧化丙烯二元醇(PPG)为软段,制备了一系列聚醚型聚氨酯(PUR)弹性体,研究了预聚体异氰酸酯指数R及软段相对分子质量对PUR动态力学性能的影响。结果表明,预聚体R值增大,即PUR的硬段含量增加,储能模量G′提高,软段相的玻璃化转变温度(Tg)升高,软硬相区的相容性增大;软段相对分子质量增加,PUR的G′下降,软段相的Tg降低,并出现硬段相的玻璃化转变,软硬相区的相分离程度增大。     

不同软段热塑性聚氨酯弹性体的合成及性能研究

以聚己二酸丁二醇酯二醇(PBA)、聚己内酯二醇(PCL)、聚碳酸酯二醇(PCDL)和聚四亚甲基醚二醇(PTMG)作为软段,采用一步法制得4种热塑性聚氨酯弹性体(TPU)。通过FTIR、电子拉力试验机、DSC、TGA和DMA分析研究了软段结构对TPU的物理机械性能、热性能和动态力学性能的影响。结果表明,在软段分子量和硬段含量相同时,PTMG-TPU和PCL-TPU较PBA-TPU和PCDL-TPU具有较低的硬度、模量、压缩永久变形和较高的弹性。PBA-TPU和PTMG-TPU显示较高微相分离程度和热稳定性;PCDL-TPU则显示较高的相混合程度。在低于玻璃化转变温度(Tg)时其储能模量降低次序为PCDL-TPUPBA-TPUPCL-TPUPTMG-TPU,Tg增大的次序为PTMGTPUPCL-TPU≈PBA-TPUPCDL-TPU。     

硬段结构对IPDI型聚氨酯弹性体结构与性能的影响

采用预聚体法合成了以异佛尔酮二异氰酸酯(IPDI)、聚醚多元醇等为主要原料,1,4-丁二醇(BDO)、三羟甲基丙烷(TMP)、1,2-丙二醇(PDO)、三异丙醇胺(TIPA)为扩链交联剂的聚氨酯弹性体PUE,讨论了扩链交联剂对弹性体拉伸强度、断裂伸长率、硬度、损耗因子、微相分离、吸水率等性能的影响规律。结果表明:随R值增加,PUE硬度增加,交联密度越大,分子规整性越高,硬度越大;相同R值下,不同硬段结构的PUE储能模量E’和tanδ变化趋势一致,Tg(SS)几乎不变,但tanδmax变化较大;相同R值下,交联密度越大,硬段链段规整性越高,内聚能越大,拉伸强度越大,吸水率越低,断裂伸长率越小,微相分离程度越大。     

黏合剂结构对胶片及推进剂力学性能的影响

为了阐明黏合剂结构对推进剂力学性能的影响,采用动态力学和单项拉伸试验方法,研究了几种典型聚酯聚醚黏合剂结构对推进剂力学性能的影响。结果表明,在不含增塑剂情况下,聚四氢呋喃(PTHF)胶片具有更高的伸长率,聚己内酯-四氢呋喃嵌段聚酯醚(HTCE)和聚己内酯(PCL)具有更高的强度;PCL、HTCE和PTHF胶片的储能模量(E′)和损耗模量(E″)依次降低,其玻璃化转变温度(T_g)分别为-43.94、-61.99和-66.98℃。增塑剂降低了链段解冻运动过程中的内耗阻力,使胶片的玻璃化温度大幅降低,PTHF、PCL和HTCE的T_g分别为-67.66、-72.27和-77.10℃,PCL的储能模量和损耗模量最高,PTHF储能模量大于HTCE、HTCE和PCL胶片的力学性能优于PTHF。推进剂的T_g由高到低顺序为PTHF、PCL、HTCE,分别为-55.27、-56.16和-57.91℃;PTHF的储能模量最大,在低温下抗冲击性能和韧性最差;HTCE推进剂的储能模量和损耗模量最低,黏合剂体系的弹性较好、损耗较低;PCL的储能模量、损耗模量和内耗峰面积均较高,在宽温度范围内的刚性和冲击韧性较好。     

1,3-丙二醇基聚酯型聚氨酯材料的合成与性能

分别采用相对分子质量为2000或3000的聚己二酸-1,3-丙二醇酯二醇,与4,4'-二苯基甲烷二异氰酸酯(MDI)反应制备NCO封端的预聚体,然后用1,4-丁二醇(BDO)扩链制备了聚氨酯材料(PU-PPA),并且与以聚己二酸-1,4-丁二醇酯二醇(PBA)所制备的聚氨酯材料(PU-PBA)进行性能对比。结果表明,聚酯型PU材料的吸水率较低;PU-PPA的软段结晶能力弱,储能模量低,柔顺性好,但其力学强度和耐水解性能差于PU-PBA材料;软段相对分子质量的增加能够提高PUPPA的微相分离程度,从而改善其力学性能,但耐水解性变差。此外,提高硬段含量能够同时提升PU-PPA的力学强度和耐水解性。     

聚氨酯阻尼材料

正聚氨酯材料广泛用于减震装置中,保护主体构件免受震动。聚氨酯是嵌段共聚物,由聚醚二元醇软段以及异氰酸酯和扩链剂构成的硬段组成。由于软段和硬段的化学性质不同,所以它们不相容,形成不同的相。阻尼性能用tanδ来表征(tanδ=E′/E″,E″表示损耗模量,E′表示储能模量)。高分子材料的化学结构决定了其tanδ。TPU是线性嵌段共聚物,可以通过改变其化学结     

中温固化氰酸酯树脂基体动态热机械分析研究

采用动态热机械分析法详细考察了中温(125℃)固化氰酸酯树脂基体的温度-模量谱,研究了连续温度变化情况下促进剂用量、固化温度、环氧树脂、多官能氰酸酯对树脂基体的模量、损耗、玻璃化转变温度等使用性能的影响。促进剂的加入有效地提高了CE树脂中温固化反应程度和固化物的Tg,加入量在1.5phr时,改性CE树脂的弹性模量在150℃处显现出GPa量级波动,但仍呈玻璃态特征,表观Tg达238℃。提高固化温度,可使DMA曲线上的弹性模量波动消失,180℃固化后的Tg与中温固化的表观Tg相近。采用E-51环氧改性CE树脂,会显著降低树脂的耐热性。E-51用量在10份,Tg在233.5℃,用量到20份以上时,CE树脂的Tg急剧降低。酚醛型氰酸酯CY-5能有效地提高树脂的Tg,用量在20份时,Tg可达289℃。     

丁胺-芴基苯并噁嗪/环氧共混树脂的性能研究

以双酚芴、正丁胺和多聚甲醛为原料,二氧六环为溶剂,通过Mannich缩合反应,合成了高纯度丁胺-芴基苯并噁嗪单体（BF-n-b）。以差式扫描量热仪（DSC）研究了苯并噁嗪单体/E-51环氧共混树脂的固化行为,通过动态热机械分析（DMA）和热重分析（TGA）研究了共混树脂的热机械和热稳定性能。结果表明,采用改进的制备方法简化了苯并噁嗪单体的合成过程,单体收率和纯度显著提高;苯并噁嗪/环氧共聚物的玻璃化转变温度（Tg）达到165~178℃,初始热分解温度（热失重5%）达312~342℃,800℃时残碳率最高达22.4%。     

环氧树脂/有机硅改性双马来酰亚胺的性能研究

以二（4氨基苯氧基）二甲基硅烷（SIDA）、双马来酰亚胺（BMI）和双酚A型环氧树脂（E-51）为原料,通过扩链反应制备了E-51/BMI/SIDA共混物。结果表明,当SIDA含量为20 %（质量分数,下同）时,E-51/BMI/SIDA的冲击强度和弯曲强度分别为38.52 kJ/m2和120.54 MPa;E-51/BMI/SIDA热失重5 %时的温度为336.8 ℃,600 ℃时的残炭量高达55.4 %;E-51/BMI/SIDA的吸水率在8 d时仅为0.78 %。     

Acrylate Copolymer/Ultraviolet Curable Oligomer Blends as Pressure-sensitive Adhesives

For the blends of acrylate copolymer [poly(2-ethylhexyl acrylate-co-acrylic acid); P(2EHA-AA)] with ultraviolet (UV) curable oligomer [urethane acrylate oligomer; UAO], pressure-sensitive adhesive (PSA) properties, such as peel adhesion, probe tack, and holding power were examined. The values of peel adhesion and probe tack of the P(2EHA-AA)/UAO blends were dramatically reduced by UV irradiation. On the other hand, all blends had a high holding power even if these blends were cured by UV irradiation. The mechanism of reduced PSA properties was investigated via dynamic mechanical properties, DSC, and dynamic contact angle (DCA). The peel adhesion decreased monotonically with increasing storage modulus, E′, and loss modulus, E″, for all non-UV and UV-cured blends. Since modulus values and glass transition temperatures, Tg, of these blends after UV irradiation were higher than those of these blends before UV irradiation, we judged that the reduced peel adhesion and probe tack values were caused by the modulus increase and the Tg increase due to UV irradiation. In other words, the ability of the deformation energy of UV-cured blends to influence the adhesive tests was reduced by the curing process. The DCAs of non-UV-cured blends were the same as those of UV-cured blends. We presumed that the segment mobility of the polymer chain on the surface did not contribute to the reduced peel adhesion and probe tack values.     

Acrylate Copolymer/Ultraviolet Curable Oligomer Blends as Pressure-sensitive Adhesives

For the blends of acrylate copolymer [poly(2-ethylhexyl acrylate-co-acrylic acid); P(2EHA-AA)] with ultraviolet (UV) curable oligomer [urethane acrylate oligomer; UAO], pressure-sensitive adhesive (PSA) properties, such as peel adhesion, probe tack, and holding power were examined. The values of peel adhesion and probe tack of the P(2EHA-AA)/UAO blends were dramatically reduced by UV irradiation. On the other hand, all blends had a high holding power even if these blends were cured by UV irradiation. The mechanism of reduced PSA properties was investigated via dynamic mechanical properties, DSC, and dynamic contact angle (DCA). The peel adhesion decreased monotonically with increasing storage modulus, E', and loss modulus, E', for all non-UV and UV-cured blends. Since modulus values and glass transition temperatures, Tg, of these blends after UV irradiation were higher than those of these blends before UV irradiation, we judged that the reduced peel adhesion and probe tack values were caused by the modulus increase and the Tg increase due to UV irradiation. In other words, the ability of the deformation energy of UV-cured blends to influence the adhesive tests was reduced by the curing process. The DCAs of non-UV-cured blends were the same as those of UV-cured blends. We presumed that the segment mobility of the polymer chain on the surface did not contribute to the reduced peel adhesion and probe tack values.     

Effect of processing conditions on physical properties of a milk fat model system: Rheology

The effect of processing conditions on rheological behavior of three blends of 30, 40, and 50% of high-melting fraction [melting point measured as Mettler dropping point (MDP)=47.5°C] in low-melting fraction (MDP=16.5°C) of milk fat was studied. The effects of cooling and agitation rates, crystallization temperature, chemical composition of the blends, and time of storage on complex, storage and loss moduli were investigated by dynamic mechanical analysis (DMA). Compression tests were performed on samples using frequency values within the linear viscoelastic range (1 to 10 Hz). Loss modulus was, on average, 10 times lower than elastic modulus and was generally not affected by processing conditions. Samples showed a more solid-like behavior that was better described by storage modulus. Storage modulus varied with all processing conditions used in this study, and even for the same solid fat content, different rheological properties were found. Storage and complex modulus increased with temperature of crystallization (25 to 30°C), even though solid fat contents of samples measured after 24 h at 10°C were the same. Moduli were higher for samples crystallized at slow cooling rate, decreased with agitation rate, and were lower for the 30–70% blend at all processing conditions used. Storage moduli also increased with storage time. Shear storage modulus was calculated from the DMA experimental data, and the results were in agreement with the values reported in literature for butter systems. Fractal dimensions calculated for these systems showed a significant decrease as agitation rate increased in agreement with the softening effect reported for working of butter.     

氟橡胶/甲基乙烯基硅橡胶共混弹性体的性能

通过机械共混法制备了氟橡胶(FKM)/甲基乙烯基硅橡胶(MVQ)弹性体,研究了二者的质量比对共混弹性体力学性能、耐油性能和动态力学性能的影响.结果表明,当FKM/MVQ(质量比,下同)为80/20时,共混弹性体具有较好的综合力学性能.随着FKM所占比例的增加,共混弹性体的耐油性能提高.当振动频率为1 Hz时,共混弹性体中MVQ相的玻璃化转变温度(Tg)比MVQ的Tg提高了约5.0 ℃,而FKM相的Tg改变不大;当FKM/MVQ为60/40时,随着振动频率由1 Hz增大到50 Hz,FKM相的Tg升高了12.9 ℃,而MVQ相的Tg变化不大.     

涤纶工业丝动态粘弹性的研究

采用动态热机械分析仪分析纺丝温度对涤纶工业丝动态粘弹性的影响,研究了纤维储能模量(E')、损耗模量(E″)及损耗因子(Tanδ)的温度依赖性。结果表明:纺丝温度300℃,涤纶工业丝初生纤维取向及结晶几率低,链段运动能力强,经后拉伸可有效提高纤维强度;在玻璃化转变温度范围内,E',E″及Tanδ均出现极大值,随温度升高,E'及E″下降,在120℃左右E'和E″再次升高,140℃左右则趋于平衡。     

盐雾老化对风电叶片用环氧树脂性能的影响

采用差示扫描量热(Differential Scanning Calorimetry,简称DSC)、红外光谱(Fourier transform infrared spectroscopy,简称FTIR)、静态力学性能测试等分析方法对复合材料风电叶片用环氧树脂浇铸体老化前后的性能进行分析,通过对比盐雾老化前后树脂浇铸体的玻璃化转变温度(Glass transition temperature,简称Tg)和力学性能,研究了环氧树脂浇铸体的老化机理。结果表明,树脂浇铸体的Tg随着老化时间的增加呈现先上升后下降的趋势,老化20天时Tg由未老化前的55℃升高到62℃,20天后开始下降,到50天时下降为51℃,比未老化的下降了4℃。随着老化时间的增加,树脂浇铸体力学强度和模量均呈下降趋势,50天盐雾老化后树脂浇铸体的弯曲强度和拉伸强度分别下降了13%和12%,而弹性模量和弯曲模量分别下降了16%和9%。     

聚碳酸亚丙酯/壳聚糖熔融共混改性研究

采用熔融共混法将聚碳酸亚丙酯(PPC)与壳聚糖(CS)共混改性,研究了CS含量对PPC/CS共混物相容性、玻璃化转变温度(Tg)、热失重温度和拉伸性能的影响,并探讨了CS改性PPC的作用机理。结果表明:PPC与CS的共混属于简单物理共混,CS对PPC的Tg影响不大,但可显著提高PPC基体的耐热性能,扩大复合材料的加工温度范围。同纯PPC相比,PPC/CS共混物的TGA曲线向高温区偏移,共混物的5%分解温度(T-5%)较PPC提高了51⁵9℃,其50%分解温度(T-50%)提高了1259℃,其50%分解温度(T-50%)提高了12²1℃;另外,共混物的TGA曲线只存在一个高温区的失重台阶,这是由于CS的引入抑制了PPC在低温区的解拉链式降解,因而只有高温区的无规降解发生。此外,随着CS含量的增加,PPC/CS共混物的拉伸强度不断增大,当CS含量增至20%时,材料的拉伸强度由纯PPC的4.7 MPa上升至12.5 MPa。