示差扫描量热法

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,示差扫描量热法,(,Differential Scanning Calorimeter，DSC),ISO 11357-1：,DSC,是测量输入到试样和参比物的热流量差或功率差与温度或时间的关系,1,DSC,与,DTA,测定原理的不同,DSC,是在控制温度变化情况下，以温度（或时间）为横坐标，以样品与参比物间温差为零所需供给的热量为纵坐标所得的扫描曲线。,DTA,是测量,T-T,的关系，而,DSC,是保持,T = 0，,测定,H-T,的关系。两者最大的差别是,DTA,只能定性或半定量，而,DSC,的结果可用于定量分析。,2,3,4,5,6,示差扫描量热测定时记录的热谱图称之为,DSC,曲线，其纵坐标是试样与参比物的功率差,dH/dt，,也称作热流率，单位为毫瓦（,mW），,横坐标为温度（,T）,或时间（,t）。,一般在,DSC,热谱图中，吸热(,endothermic),效应用凸起的峰值来表征 (热焓增加)，放热(,exothermic),效应用反向的峰值表征(热焓减少)。,7,曲线,玻璃化转变,结晶,基线,放热行为,（固化，氧化，反应，交联）,熔融,固固,一级转变,分解气化,DTA,曲线,吸热,放热,T,(),dH/dt(mW),T,g,T,c,T,m,T,d,DSC,8,4.1 玻璃化转变温度的测定,d,Q/dt,d,Q/dt,温度,温度,T,g,T,g,1/2,从,DSC,曲线上确定,T,g,的方法,9,T,g,体积,温度,玻璃化转变温度前后体积变化率不同,10,体积收缩过程是一级过程：,v,为体积松弛时间，即过剩自由体积排出,l/e,的时间。,聚合物体内过剩的自由体积越多，收缩越快。,玻璃化转变的动力学本质,11,聚苯乙烯：100,C,的松弛时间约为0.01秒，95,C,时约为1秒，77,C,时约为一年。以1,C/,min,的降温速度测定,PS,的玻璃化温度约为90,C,，即松弛时间为1-5,min,的温度范围。,100,95,91,90,89,88,85,79,77,0.01秒,1秒,40秒,2分钟,5分钟,18分钟,5小时,60小时,1年,温度(,C,),v,12,Heat Flux,Endothermic,Exothermic,Glass,Liquid,T,g,T,g,10 50 90,Temperature,C,热焓松弛对,T,g,测定的影响,20,C/min,上曲线：无预处理,下曲线：,150,C,保温1,min,迅速冷却至室温,(320,C/min),样品：某线形,环氧树脂,13,10 50 90,Temperature,C,(320),(40),(10),(2.5),(0.62),51,51,51,52,54,样品冷却速率对,T,g,测定的影响,150C,预热后以,( ),C/min,冷却速率降到,T,g,以下再测定,14,10 50 90,Temperature,C,0,2,25,53,56,51,样品放置时间对,T,g,时间的影响,从,150C,以,320C/min,降到室温后放置 天再测定,15,-,样品用量,1015 mg,-,以,20,C/min,加热至发生热焓松弛以上的温度,-,以最快速率将温度降到预估,T,g,以下,50,C,再以,20,C/min,加热测定,T,g,对比测定前后样品重量，如发现有失重则重复以上过程,T,g,测定的推荐程序,16,研究实例：轮胎橡胶,T,g,测定,轮胎橡胶,T,g,的重要性：,T,g,值高,(,约,-40,C)，,抓着性高，但滚动阻力大，耐磨差，耐低温性差,T,g,低,(,约,-90,C),，滚动阻力小，耐磨高，耐低温性高，但抓着性差,因此轮胎橡胶都是不同胶的共混物,17,ESBR,SSBR,BR,丁二烯橡胶,-,100 -20,C,NR,天然橡胶,IR,异戊二烯橡胶,常用的轮胎胶,丁苯橡胶,-100,100,C,18,丁二烯橡胶是三种单元的共聚物，即顺式、反式、乙烯基。,BR,的,T,g,可由,Gordon-Taylor,公式计算：,W,i,A,i,(T,g,- T,g, i,) = 0,其中,W,i,为单元,i,的重量分数,，,T,g,为共聚物的玻璃化温度，,T,g, i,为单元,i,均聚物的玻璃化温度,A,i,是一个常数，一般取体积膨胀系数,19,W,i,A,i,(T,g,- T,g i,) = 0,假定有三个组分：,W,1,A,1,(T,g,- T,g1,) + W,2,A,2,(T,g,- T,g2,) + W,3,A,3,(T,g,- T,g3,) = 0,T,g,(W,1,A,1,+ W,2,A,2,+ W,3,A,3,),= W,1,A,1,T,g1,+ W,2,A,2,T,g2,+ W,3,A,3,T,g3,20,W,为重量分数，下标,c, t, v,分别代表顺,-l,4,反,-l,4,和乙烯基结构,T,g,c,t,v,分别代表三种结构均聚物的,T,g,K,n,=,(n+l),/,1,为体积膨胀系数之比,聚丁二烯的,T,g,可用下式计算,21,T,g, c,= 164 K (-109,C),T,g, t,= 179 K (-94,C) K,1,= 0.75,T,g, v,= 257 K (-16,C)K,2,= 0.50,W,c,+ W,t,+ W,v,= 1.0,误差,0.5,C,22,在此基础上可扩充为计算,SSBR,的公式,T,g, s,=,聚苯乙烯的,T,g,，378 K,W,s,=,苯乙烯单元的重量分数,K,3,0.6,23,( ) %,wt styrene,(on total polymer),DSC T,g,C,1.2,BR fraction (of the total BR part),20,10,0,10,20,30,40,50,60,70,80,90,100,0.00 0.20 0.40 0.60 0.80 1.00,(70),(60),(50),(40),(30),(20),(10),(0),1,2结构与,S,单元对,SSBR,T,g,的影响,24,Temperature (,C),Heat Flow (W/g),0.30,0.25,0.20,0.15,0.10,0.05,0.00,120 110 100 90 80 70 60 50 40,internal mixer (50,C,),prepared sample,sample prepared from,cyclohexane solution,T,g,effects of SSBR/BR (75/25) blends,二者不相容，两个,T,g,25,sample prepared from,a toluene solution,internal mixer (50,C,),prepared sample,Thermally treated,Temperature (,C),Heat Flow (W/g),0.24,0.22,0.20,0.18,0.16,0.14,0.12,0.10,0.08,0.06,0.04,0.02,0.00,90 80 70 60 50 40 30,低,vinyl (8.5 %wt),与高,vinyl (40.5 %wt) SSBR,完全相容，只有一个,T,g,，,但可以从峰加宽与峰位移判断是共混物。,26,T,g,-value SSBR blends,calculated,measured,high vinyl content SSBR weight fraction,40,45,50,55,60,65,70,75,80,0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0,计算值与测定值的比较,27,0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0,40,45,50,55,60,65,70,75,80,T,g,of oil-extended SSBR and ESBR systems,measured values,T,g,oil-extended rubber,C,SSBR,aromatic oil,ESBR,SSBR,naphtenic oil,oil wt fraction,充油体系,常用芳香油,T,g,232K (-41,C),或萘油,T,g,208 K。,芳香油,T,g,高于,SBR，,使,T,g,升高，萘油使,T,g,降低。,28,4.2 熔融与结晶,表征熔融的三个参数：,T,m,:,吸热峰峰值,H,f,：,吸热峰面积,T,e,：,熔融完全温度,表征结晶的两个参数：,T,c,：,放热峰峰值,H,c,：,放热峰面积,exo,1.0,0.8,0.6,0.4,0.2,0.0,100 150 200 250 300 350,Temperature,C,T,m,H,f,T,e,T,c,H,c,29,4.2,mg,3.1mg,5.2mg,8.1mg,12.4mg,6.0,5.5,5.0,4.5,4.0,3.5,3.0,2.5,2.0,1.5,1.0,0.5,0.0,6.0,5.5,5.0,4.5,4.0,3.5,3.0,2.5,2.0,1.5,1.0,0.5,0.0,200 210 220 230 240 250 260 270,Temperature (,C),Heat Flow (W/g),样品量与,T,m,值的关系,30,如果熔融不完全，残余晶粒会造成“自成核”，使结晶温度升高。从表可以看出，,PP,样品至少应在210,C,熔融。,1.,heating,T,max,.,C,2.,cooling,3.,heating,T,m1,C,H,f1, J/g,T,c,C,H,c, J/g,T,m2,C,H,f2, J/g,162.5,100,230,108.6,101,160.9,95,162.1,102,220,108.7,99,160.5,96,162.5,97,210,108.7,96,161.0,95,162.5,99,200,109.2,102,161.0,90,162.4,88,190,109.3,98,161.0,95,162.2,99,180,110.0,98,161.2,98,31,1.,heating,T,max,.,C,2.,cooling,3.,heating,T,m1,C,H,f1, J/g,T,c,C,H,c, J/g,T,m2,C,H,f2, J/g,162.5,100,230,108.6,101,160,.9,95,162.1,102,220,108.7,99,160,.5,96,162.5,97,210,108.7,96,161,.0,95,162.5,99,200,109.2,102,161,.0,90,162.4,88,190,109.3,98,161.0,95,162.2,99,180,110.0,98,161.2,98,总结出：,T,m1,: 162.4,C,0.2,C H,f1,: 97 J/g,5 J/g,H,f,误差大是由于取基线造成的。,H,c,:,99 J/g,2 J/g T,m2,: 160.9,C,0.2,C H,f2,: 95 J/g,3 J/g,后三个值重复性提高是由于样品熔融后与容器充分接触所致。,32,结晶与熔融点必须反复循环加热冷却，才能得到可重复数据。,T,m,与,T,c,测定的重复性在,3,C,左右,这一误差比,T,g,测定要高,33,PP,的结晶与熔融,无规,PP,T,g,=,-21,C,间规,PP,(,结晶度,25 %,wt.) T,m,=,133,C,等规,PP,(,结晶度,50 %wt.) T,m,= 160,C,i-PP,中最常见的是,晶格,单斜，,T,m,=,160,C.,压力下结晶会产生,晶格，六方，,T,m,=,152,C,34,i-PP,结晶温度为,110,C，,过冷度为,50,C。,模塑效率太低。,成核剂可缩短模塑时间，减小球晶尺寸，同时提高光学/力学性质,4-biphenyl carboxylic acid,与 2-,naphtoic acid,可将,T,c,从,110,C,提高到,130,C .,PP,的成核剂,35,Talc % wt.,Carbon black% wt.,Total add.,% wt.,T,c,C,H,c,J/g,T,m2,C,0.00,0.00,0.00,110,91,158,0.05,0.00,0.05,115,97,161,0.19,0.00,0.19,118,95,161,0.00,0.47,0.47,120,91,162,0.53,0.00,0.53,118,97,161,0.38,0.59,0.97,124,95,163,0.35,0.70,1.05,125,96,163,0.00,1.37,1.37,125,97,163,0.76,0.85,1.61,125,96,164,9.57,1.02,10.59,114,95,160,滑石粉和碳黑作成核剂的效果,36,PP T,m2,-value/T,c,-value,Additives:talc/carbon black,PP T,c,-value,C,128,126,124,122,120,118,116,114,112,110,108,0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8,Additive content, %wt,PP Tm2-value, C,T,c, C,166,165,164,163,162,161,160,159,158,157,156,108 112 116 120 124 128,PP,成核剂的,效果图示,37,成核效率,T,ca,:,加成核剂后的结晶温度,T,c1,:,未加成核剂的结晶温度,T,c2,:,体系自成核的最高结晶温度,38,加炭黑0.70,wt%, 滑石粉0.35,wt%,的,PP: T,c,=125,C,加滑石粉0.53,wt%,的,PP: T,c,=118,C,39,退火对熔点与焓值的影响,样品：,HH-SB-35,等规度：96%,M,w,= 300,000 M,w,/M,n,5.0,4mg,样品加热到退火温度,T(a),保持时间,t(a),冷却到,20,C,，再加热到,220,C,加热/冷却速率均为,20,C/ min,背景：,PP,的平衡熔点为,185,或,208,C,。结晶温度仅为,110,130,C,左右。这样大的差异表明结晶与热历史关系密切。,40,Temperature (,C),Heat Flow (W/g),7.0,6.5,6.0,5.5,5.0,4.5,4.0,3.5,3.0,2.5,2.0,1.5,1.0,0.5,130 140 150 160 170 180 190,Annealed at,163,C during:,30min,15min,5min,退火时间的影响,该图表明火时间应为,30min,41,Temperature (,C),Heat Flow (W/g),7.0,6.5,6.0,5.5,5.0,4.5,4.0,3.5,3.0,2.5,2.0,1.5,1.0,0.5,130 140 150 160 170 180 190,163,C,164 C,165 C,30 min,annealed at:,退火温度的影响,42,T(a),C,T,c,C,T,m,C,H,f,J/g,T,m, ,C,H,f, , J/g,146,161.0,76,150,163.4,81,152,165.1,79,156,168.7,78,159,172.0,91,161,174.4,109,162,175.8,110,163,175.8,107,164,141.4,178.3,31,161.3,69,164.5,140.8,178.7,12,163.5,81,165,140.9,179.2,11,164.2,89,166,138.9,179.2,2,164.2,97,166.5,138.3,179.5,1,164.6,99,167,135.8,163.6,100,略有增加,T,m,随,T(a),增加,H,f,经历极大值,表明结晶最完善,曲线双峰,T,m,呈最大值,H,f,降为零，,H,f,上升，,T,m,恒定。,H,f,T,m,下降,43,Annealing temperature Ta,C,T,m,-/H,f,值随退火温度的变化,180,178,176,174,172,170,168,166,164,162,160,180,160,140,120,100,80,60,40,20,0,145 151 157 163 169 175,T,m, 0.993; 斜率从,13.5 phr,的,0.49,增加到,24 phr,的,0.55,13.5,17,20.5,67,Time/curing agent concentration relation necessary to reach a T,g,-value of the,cured product of at least 100,C,Cure time at 180 C , s,(Cure temperature 180 C),Epoxy resin based powder coating system,curing agent concentration,phr,1000,200,10 12 14 16 18 20 22 24 26,T,g,高于,100,C,所需时间,68,聚合反应动力学,含不同长度脂肪链的酰亚胺的聚合,由亚甲基丁二酸酐与脂肪二胺通式为,H,2,N-(CH,2,),n,-NH,2,，,其中,n=6,8,10,和12出发，合成一系列结构类似的含脂肪链的酰亚胺，利用,DSC,研究具有如下结构的这类甲基顺丁烯酰亚胺的聚合动力学。,C,O,N,(CH,2,),n,C,O,C,HC,H,3,C,C,CH,2,CH,2,O,O,N,C,C,69,甲基顺丁烯酰亚胺(,n=6),的,DSC,升温曲线,总面积,A:,总放热,a:,时刻,t,放热之和,已反应分数,A-a:,时刻,t,未反应分数,dQ/dt:,反应速率,放热,dQ/dt,吸热,340,T 440,a,A-a,T/K,熔融吸热,(72,C),70,可由1条升温,DSC,曲线求得在不同温度处的,k,值，于是由,Arrhenius,图(,lgk1/T,),的斜率可求得聚合反应活化能。实验结果显示,Arrhenius,图线性良好，反应符合1级反应。随柔顺亚甲基链段长度的增加(甲基数由6增加至12)，聚合活化能从75,kJ/mol,降至30,kJ/mol。,如假定该反应为1级反应，便可直接写出速率方程：,dQ/dt = k(A-a),k = (dQ/dt)/(A-a),T,a,A-a,dQ/dt,71,P(S-PFS):,苯乙烯-对氟苯乙烯的共聚物,PPO:,聚苯醚,PFS,的摩尔含量为8-56%时，体系相容。高于56%后，发生相分离。,P(S-PFS),和,PPO,共聚混合物的,DSC,曲线,PFS,摩尔含量,8%,16%,25%,36%,46%,49%,56%,67%,78%,热流量,107 227,T(,C,),4.4 相容性研究,72,S.C.Lee et al., Polymer, 1997, 38, 4831.,.,The arrow indicates the position of T,g,PEN/PET(50/50) blend The time indicates the reaction time at 280,C,Temperature,C,Temperature,C,3min,5min,7min,9min,11min,13min,15min,20min,180min,PEN/PET(w/w),Exothermic,100/0,70/30,50/50,30/70,0/100,0 50 100 150 200 250 300,0 50 100 150 200 250 300,Exothermic,PEN、PET,的共混与酯交换过程,73,Change of the glass transition behavior with the reaction time at 280,C for the PEN/PET (50/50) blend,130,120,110,100,90,80,70,EN-rich phase,ET-rich phase,0 10 20 30 40 50 60 80,Reaction Time (min),T,g,(,C),74,140,130,120,110,100,90,80,70,0 20 40 60 80 100,T,g,(,C),EN Content (wt%),EN/ET copolymers prepared by heat treating of PEN/PET blends at 280,C for 180min.,T,g,= w,1,T,g1,+ w,2,T,g2,75,聚苯乙烯/离聚物共混,聚苯乙烯：,M,n,=1.06,1,0,5,，M,w,/M,n,=1.93,聚苯乙烯磺酸锌盐：,增容剂：苯乙烯/乙烯基吡啶嵌段共聚物,Compatibilization of blends of polystyrene and zinc salt of sulfonated polystyrene by poly(styrene-,b,-4-vinylpyridine) diblock copolymer,Polymer 40 (1999) 22392247,76,扫描电镜,液氮折断，,THF,去除,PS,相,(,a) 0 (b) 2.0 (c) 4.1 (d) 7.3,PS/Zn-SPS 70/30 (wt/wt)+P(S-,b,-4VPy),括号中数字为增容 剂量,即,P(S-,b,-4VPy),重量/两种,PS,总重量,77,低于此配比时一个,T,g,，,相容,高于此配比时两个,T,g,，,不相容,Zn-SPS/P4VPy,的相容性,40 60 80 100 120 140 160 180,Temperature (,C),ENDO,88.4/11.6,93.2/6.8,96.6/3.4,0/100,锌离子与吡啶氮化学计量比为93.2/6.8 (,wt/wt),Zn-SPS/P4VPy,78,neat PS：100.2,C,neat Zn-SPS： 122.2,C,70/30 blends + P(S-,b,-4VPy),(c) 0：,2,T,g,(d) 2.0 wt%：,2,T,g,(e) 4.1 wt%：,2,T,g,(f) 7.3 wt%：,3,T,g,40 60 80 100 120 140 160 180,a,b,c,d,e,f,Temperature (,C),ENDO,Zn-SPS,为聚苯乙烯磺酸锌盐,共混体系的相容 性,79,Viscoelastic and thermal properties of collagen/poly(vinyl alcohol) blends,Biomoteriols 16 (1995) 785-792,聚乙烯醇与胶原蛋白合金,背景：生物材料力学性能差，合成材料生物相容性差，二者结合后是否相容？,80,PVA/,胶原合金的,DSC,一次扫描有严重热焓松弛，二次扫描消失,峰为胶原的,denaturation(,变性)，二者,Tg,接近，无法判断是否相容,一次扫描 二次扫描,图中数字为胶原,wt%,干,PVAT,g,=80,C，T,m,=227,C,含水,PVAT,g,=42,C,0 40 80 120,endo exdo,100,0.1,W/g,0 40 80 120,endo exdo,0.1,W/g,T(,C,),T(,C,),50,30,0,70,100,70,50,30,0,81,PVA/,明胶合金的,DSC,一次扫描 二次扫描,清楚地出现两个,Tg，,且不随组成变化，表明二者不相容,0 40 80 120,endo exdo,100,0.1,W/g,T(,C,),0 40 80 120,endo exdo,0.1,W/g,T(,C,),0,30,50,70,100,70,50,30,0,82,从,PVA/,明胶合金,DSC,谱图测量的吸热幅度与组成呈线性关系，也表明不相容,0.8,0.6,0.4,0.2,0,0.8,0.6,0.4,0.2,0,0 0.5 1,明胶重量分数,W, C,p,(J/g,C,),低温转变(,PVA),高温转变(明胶),83,4.5 用,DSC,测溶度参数,先将被测物置于封闭容器中10,min，,达到平衡后打开容器盖，蒸发液体，测定焓值。,84,A,B,A:DSC cell base,B:polycarbonater cell cover,Stopping block,Spring loaded,magnets holder,magnets,mild steel lid,rubber O-ring,仪器改造示意图,85,Sample cuphole diam.,Average,Hvap.25 measured, kJ/mol,Correction factor,0.5,mm.,38.4,0.4,1.14,3.0,mm.,39.5,0.2,1.11,4.0,mm.,39.0,0.2,1.13,仪器用水校正：水的焓值：43.9,kJ/mol.,86,MCAL/SEC,5.0,2.5,0.0,Time (min),1 2 3 4 5 6 7 8,A,B,C,DSC curve of the vaporization of ethyl propionate,A,点：开盖,B,点：完全蒸发,C：,积分基线,87,solvent,boiling,tempera,ture,C,Hvap.25,exper.,kJ/mol,Hvap.25,literat.,kJ/mol,+/-,%,acetone,57,30.8,30.5,+1.0,methanol,65,38.0,37.4,+1.4,ethanol,79,42.1,42.3,-0.5,4-,methyl-2,pentanone,116,40.6,40.6,0.0,2-,heptanone,147,47.3,47.2,+0.2,n-dodecane,214,62.6,61.3,+2.1,测试结果与文献值,88,MCAL/SEC,0.30,0.15,0.00,Time (min),0 6 12 18 24 30 36 42 48 54 60,DSC curve of the vaporization of n-dodecane at 25,C,endo,89,56,53,50,47,44,41,38,35,32,29,70 80 90 100 110 120 130 140 150,n-acetates,branched acetate,n-propionates,branched propionate,Molecular weight,Heat of vaporizatrion at 25,C, kJ/mol,90,完,91,PEEK,和,PEI,的相容性，第一次（红）和第二次加热（绿），20,K/min。,第一次时，,PEEK,的,T,g,为147,C，PEI,的,T,g,为217,C。,第二次时，合并为一个,T,g,:172,C。,在224,C,时,PEEK,发生冷结晶。,Glass transition (2),Onset: 155.8,C,Midpt:172.1,C,Inflpt: 166.8,C,Endpt: 188.4,C,Del cp: 0.19 J/(g,K),exo,DSC/mW/mg,1.0,0.8,0.6,0.4,0.2,0.0,338.4,C (2),29.07 J/g,340.9,C (1),29.16 J/g,-20.66 J/g (1),223.9,C,100 150 200 250 300 350,Temperature,C,214.5,C (1),92,