采用DSC测量PEG_(10000)熔融焓变测定条件的研究

采用不同的升温速率和样品用量,分别测得差示扫描量热法(DSC)特征曲线和PEG10000的熔融焓变。结果表明:用DSC测试PEG10000的熔融峰温度(Tp)和熔化焓(△H)时,尽可能保证外界环境的一致,并使仪器降至原来的温度,消除热历史的影响。在仪器允许的范围内,低升温速率及减少样品用量可使熔融峰更尖锐、明显,并使用保护气体以防止PEG的氧化。     

聚丙烯熔融特性与MDSC条件的相关性

用调制式差示扫描量热法研究了聚丙烯(PP)升温过程熔融特性与线性升温速率（β)、温度调制振幅（AT)和调制周期(p)的相关性。实验结果表明，在低β时，总热流部分PP熔融呈现双峰；β加快时，呈现单熔融峰。随β加快，不可逆热流部分熔融热(△H)增加；可逆热流部分出现明显的放热峰。随p延长，总热流部分和不可逆热流部分的熔融峰温(Tp)基本不变，起始熔融温度(Ton)降低；但△H前者不变，后者增加；可逆热流部分从吸热变成放热，放热峰温移向高温。总热流和不可逆热流部分的Tp和Ton不受AT的影响，但随AT增大△H前者不变，后者降低。     

热氧处理条件对聚丙烯粉料DSC曲线形态的影响

发现热氧处理条件对聚丙烯粉料DSC曲线的形态变化有很大影响。随着热氧处理时间的延长,聚丙烯粉料的第一次升温熔融曲线和第二次升温熔融曲线的熔融峰温都会逐渐下降(左移)。第一次升温熔融曲线的熔融峰宽逐渐变窄,峰高逐渐变高;而第二次升温熔融曲线却熔融峰宽逐渐变宽,峰高逐渐变低。在热氧处理时间为0.5~5 h之间时,第一次升温熔融曲线会出现一个很宽的平台状小熔融峰,当热氧处理时间为12 h和14 h时,第二次升温熔融曲线的孪生双峰最明显。随着热氧处理时间的延长,聚丙烯粉料结晶峰温呈现向较低温(向左)方向移动的趋势。     

PEN非等温冷结晶动力学的研究

采用差示扫描量热(DSC)法对聚萘二甲酸乙二醇酯(PEN)的非等温冷结晶动力学进行研究;通过改变升温速率,讨论了PEN冷结晶起始温度与峰顶温度之间存在差值的原因;对比了两种不同的冷结晶起始点的确定方法对冷结晶动力学常数的影响。结果表明:以DSC曲线偏离基线作为PEN冷结晶的起始点,得到的表观Avrami指数很大;用基线延长线与DSC曲线的切线的交点作为冷结晶的起始点和结束点,得到的表观Avrami指数为2.55,且不随升温速率的变化而变化,与等温熔融热结晶方法得到的结果接近,具有相似的结晶生长方式。     

聚苯硫醚PPS结晶性能的影响因素分析

采用差示扫描量热法(DSC)研究了分子结构、熔融温度、熔融时间及剪切作用对聚苯硫醚(PPS)结晶性能的影响,并通过热台偏光显微镜研究了结晶过程中PPS的晶体形态变化。结果表明,两种PPS在结晶性能、结晶形态方面存在明显差异,相比Keji-PPS,Kureha-PPS在结晶时成核速率更快,且结晶温度更高;在同等物料状态下,同一PPS粉末料和颗粒料的结晶温度和熔融温度也存在较大差别;熔融温度和熔融时间对Kureha-PPS的结晶性能影响较大,剪切对其结晶性能影响则较小;随着熔融温度的升高,其最大结晶温度下降,而随着熔融时间的增加,其最大结晶温度增大;Kureha-PPS在降温结晶过程中,所形成的球晶尺寸小而细密。     

结晶条件对超高分子量聚乙烯熔融再结晶行为的影响

应用常压差示扫描量热(DSC)仪和高压DSC仪研究了熔融温度、熔融时间、冷却速率以及压力对不同分子量的超高分子量聚乙烯(PE–UHMW)熔融再结晶行为的影响。常压DSC的研究表明,随着熔融温度、熔融时间以及冷却速率的增加,PE–UHMW的结晶峰值温度(Tc)逐渐下降。在相同的熔融温度和熔融时间下,PE–UHMW的Tc随分子量的增加而逐渐增加,但在所研究的冷却速率范围内(2.5～40℃／min),在相同的冷却速率下,Tc随分子量的增加变化不大。高压DSC的研究结果表明,结晶过程中增加压力导致PE–UHMW的Tc有所下降,并且结晶峰半峰宽变大。     

粉状发泡胶固化工艺和动力学研究

本文通过原材料选材和配方优化研发了可以在较低温度固化的耐高温粉状发泡胶.采用动态差示扫描量热分析(DSC)研究了发泡胶的固化特性.基于不同升温速率(β)下固化起始温度Tonset和峰值温度Tp的变化,获得了Tp对lnβ的线性方程,可以更合理地确定固化温度参数.发泡性能是蜂窝夹层结构制造中一项重要的工艺性能,在相同固化时...     

差示扫描量热法研究硬聚氯乙烯管材的加工温度

通过差示扫描量热法(DSC)研究了硬聚氯乙烯(PVC)管材的加工温度(Tp),研究了制样效果,干扰峰,不同取样位置对Tp的影响。结果表明,试样与样品盘越充分接触,得到的DSC曲线呈现的Tp峰越好;管材在生产过程中使用润滑剂聚乙烯(PE)蜡,DSC曲线会在130℃左右出现干扰峰;管壁中心部位的Tp低于管壁内外表面的Tp。     

成核PP的结晶过程与熔融过程研究

研究了PP在α成核剂作用下的结晶与熔融过程,通过差示扫描量热法(DSC)对成核PP(nPP)的降温与升温过程进行了扫描。结果发现,α成核剂使PP的结晶温度显著提高,结晶速率加快;α成核剂使PP的熔融温度和熔融焓提高,不改变PP的平衡熔点。     

测试速率对PEG/GO定型相变材料熔融和结晶性能的影响

以聚乙二醇/氧化石墨烯(PEG/GO)定型相变材料为测试样品,采用差示扫描量热法(DSC)对其熔融、结晶性能进行了表征,研究了测试速率(即升/降温速率)对该相变材料熔融、结晶温度和热焓的影响。结果表明:随着降温速率的增加,PEG/GO相变材料的结晶温度逐渐降低;随着升温速率的增加,材料的熔融温度逐渐提升;测试速率越高,焓值越小;随着GO加入量的增加,升降温时的焓值均呈现降低的趋势;相同GO含量的PEG/GO定型相变材料,其熔融焓总是大于同等测试速率下得到的结晶焓,而且测试速率越快,差值越大;在相同测试速率下,GO的添加量基本不会对PEG/GO相变材料的熔融、结晶温度产生影响。     

反式-1,4-聚异戊二烯的结晶性

采用差示扫描量热仪、傅里叶变换红外光谱、偏光显微镜和X射线衍射仪等研究了反式-1,4-聚异戊二烯(TPI)的结晶性。结果表明,在TPI的差示扫描量热分析中,随着升温速率提高,第1次升温曲线上的β晶型熔融温度移向高温;而第2次升温曲线上的α晶型结晶熔融峰逐渐消失,且与第1次升温时相比β晶型的熔融温度偏高;而随着降温速率的提高,TPI的结晶峰向低温方向位移。用不同方法制备的TPI薄膜可以得到球晶、碎晶和捆束状晶体。与浇铸薄膜相比,热压薄膜傅里叶变换红外光谱曲线上的843 cm-1和980 cm-1两侧各出现了2个肩峰,而890 cm-1处的结晶峰消失。拉伸后在TPI的X射线衍射谱线上,0.47 nm和0.39 nm晶面间距的所属峰形比拉伸前要尖锐得多,而0.33 nm晶面间距所属峰则弱化。     

Multiple melting behavior of polyphenylene sulfide blends with polyamide 6

Although there are many studies on the multiple melting behavior of polyphenylene sulfide (PPS) homopolymer, similar investigations on PPS component in PPS blends with thermoplastics are relatively rare. In the present paper, the multiple melting behavior of PPS blends with polyamide 6 (PA6) have been investigated by differential scanning calorimetry (DSC). The double melting peaks are also observed for PPS in the blends. Although the annealing temperature and time as well as the heating rate of DSC scanning are different, the lower melting peak temperature of PPS in the blend is higher than that of pure PPS and the higher melting peak temperature is lower than that of pure PPS. It is suggested that PA6 can accelerate the cold‐crystallization of amorphous PPS due to the possible presence of interfacial interaction between the component polymers to induce the heterogeneous nucleation, and increase the perfection of PPS crystals. The multiple melting behavior of PPS in the blends are explained by recrystallization. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1579–1585, 2000     

Multiple melting behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) investigated by differential scanning calorimetry and infrared spectroscopy

The multiple melting behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)) (HHx = 12 mol%) isothermally crystallized from the melt state has been characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The influence of different experimental variables (such as crystallization temperature, time, and heating rate) on the multiple melting behavior of P(HB-co-HHx) was investigated by using DSC. Moreover, it has been further examined by monitoring intensity changes of the characteristic IR bands during the subsequent heating process. For the isothermally crystallized P(HB-co-HHx) samples, triple melting peaks were observed upon heating. The weak lowest-temperature DSC endotherm I always appears at the position just above the crystallization temperature, and shifts to a higher temperature linearly with the logarithm of the crystallization time. The combination of DSC and IR results suggested that the occurrence of peak I was a result of the melting of crystals formed upon long-time annealing. As for the other two main melting endothermic peaks, endotherm II corresponds to the melting of crystals formed during the primary crystallization, and endotherm III is ascribed to the melting peak of the crystals formed by recrystallization during the heating process.     

Melting and crystallization behavior of PA1010/TPU blends

PA1010/TPU blends were prepared by melt blending. The melting, crystallization behavior, and isothermal crystallization kinetics were investigated using differential scanning calorimetry (DSC). The results showed that the DSC thermograms of blend samples exhibit double melting peaks. With increasing the TPU content, the position of the double melting peaks shifted to a lower temperature, and the total heat of fusion decreased. With increasing the heating rates, the position of the lower melting peak shifted to a higher temperature, while the position of the higher melting peak shifted to a lower temperature; however, the total heat of fusion remained almost constant. With prolonging the annealing time and increasing the crystallization temperature, the position of the lower melting peak shifted to a higher temperature, while the position of the higher melting peak almost did not change; however, the total heat of fusion increased. The addition of TPU could promote the crystallization of PA1010 but not affect the crystallization mechanism. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 839–844, 2004     

TPI及SBR/TPI并用胶结晶特性的研究

使用差示扫描量热仪(DSC)研究了纯TPI粉末与SBR/TPI并用胶的结晶特性。结果表明,TPI粉末的第1次升温曲线上,β晶体的熔融温度随升温速率的增大逐渐提高,α晶体熔融峰高于β晶体;消除热历史后,β晶体熔融峰高于α晶体,且α晶体随着升温速率的提高逐渐消失;与第1次测试结果相比,第2次升温测得的结晶度呈下降趋势。冷冻作用能够稍微增大未填充SBR/TPI并用胶的结晶度。升温速率对未填充SBR/TPI并用胶晶体熔融峰的峰形分辨率有较大影响。随着TPI用量的增大,未填充并用胶及其硫化胶的结晶熔融焓均增大。填充炭黑后,SBR/TPI并用胶及其硫化胶都比未填充时的峰形钝化变宽。     

Study on the influence of ageing on thermal decomposition of double‐base propellants and prediction of their in‐use time

A comparative study of the thermal decomposition of naturally and artificially aged double‐base propellants has been carried out at five different heating rates in a dynamic nitrogen atmosphere using differential scanning calorimetry (DSC) technique. The results show that there is only one decomposition peak on DSC curves, and this decomposition has been accelerated by ageing. The influence of the heating rate on the DSC behaviour of the propellants was verified. The kinetic parameters such as activation energy and frequency factor and the thermodynamic parameters such as the enthalpy of activation, free energy of activation and critical explosion temperature for the compounds were obtained from DSC data using non‐isothermal methods proposed by Kissinger and Ozawa. On the other hand, a prediction of the in‐service period by van't Hoff's equation was performed and compared with the experimental results in order to check the constancy and validity of this method. As a result, the prediction procedure used to obtain the time–temperature profile was achieved with good accordance. Copyright © 2012 John Wiley & Sons, Ltd.     

不同温度熔融条件下聚对苯二甲酸乙二醇酯的结晶与熔融行为

分别采用低黏度和高黏度的聚对苯二甲酸乙二醇酯(PET)树脂切片,利用差示扫描量热分析(DSC)的方法研究不同的熔融温度条件对PET结晶行为和熔融行为的影响。结果表明:和高黏度PET相比,低黏度PET的结晶过程对熔融温度的变化极其敏感,不同熔融温度将对它的结晶行为与熔融行为产生显著的影响;在同等条件下,低黏度PET结晶速率快且易生成稳定的结晶结构,其稳定结晶的熔融温度要比高黏度PET高数度;总体上,采用较低的熔融温度有利于提高PET结晶温度和结晶速率,而采用较高的熔融温度有利于提高PET结晶的稳定性。     

Study of multiple melting behaviour of syndiotactic polystyrene in β‐crystalline form

A series of syndiotactic polystyrene (SPS) samples in β‐crystalline form were prepared by cooling from the melt at various rates. The effects of cooling rate from the melt, DSC heating rate and annealing on the multiple melting behaviours of β crystals were investigated by differential scanning calorimetry (DSC) and temperature modulated differential scanning calorimetry (TMDSC), from which the nature of the multiple melting behaviour was determined. The two melting endotherms of β‐form crystals were considered to arise from the occurrence of simultaneous melting, recrystallization and remelting processes in the melting region. It is suggested that the lower melting endotherm is due to the melting of imperfect β crystals originally present in the sample, whereas the higher melting endotherm comes from the melting of recrystallized SPS crystals, ie more perfect β crystals that formed during the DSC scanning process. © 2000 Society of Chemical Industry     

PA6对聚苯硫醚多峰熔融行为的影响

用差示扫描量热法（DSC）研究了聚苯硫醚（PPS）/聚酰胺（PA）6共混物熔融多峰行为，PPS及其共混物均出现熔融多峰现象。但共混物呈现更加复杂的熔融行为，虽然退火结晶温度，时间和DSC扫描速率不同，但共混物中PPS的低温熔融峰温明显地比纯PPS的高，认为PA6与PPS间的相互作用促使PPS无定形态的退火结晶完善性提高。熔融多峰现象用重组机理来解释。