PPS／PEEK熔融共混物DSC多次扫描研究

借助ＤＳＣ研究ＰＰＳ／ＰＥＥＫ共混物熔融时间，ＰＥＥＫ粒径及ＰＰＳ组分对共混物中ＰＥＥＫ结晶熔融行为的影响，结果表明，ＰＥＥＫ粒径由５００～１０００μｍ减小至２００～５００μｍ时，ＰＥＥＫ与ＰＰＳ相互作用增大，ＰＥＥＫ的结晶峰由单峰分裂为双峰，其高温结晶峰向高温移动，峰强随熔融时间延长而减弱，低温结晶峰向低温移动，峰强随熔融时间延长而增大，熔融时间延长时，退火后ＰＥＥＫ的低温熔融峰强增大，而高温熔     

熔融条件对尼龙612TPU共混物中尼龙结晶行为的影响

用DSC研究了熔融温度与熔融时间对尼龙612(PA612)/聚酯型热塑性聚氨酯弹性体(TPU)共混体系中PA612结晶行为的影响。不同的熔融温度和熔融时间对PA612/TPU的结晶行为影响表明,在相同的熔融温度条件下,PA612的结晶峰温度随着熔融时间的延长向低温方向移动,结晶峰温度和结晶焓值逐渐降低,结晶峰逐渐变宽;在相同的熔融时间条件下,PA612的结晶峰温度随着熔融温度的提高向低温方向移动,结晶峰温度按200℃220℃240℃降低。     

低熔点聚酰胺的结晶和熔融行为

采用差示扫描量热法和X射线衍射法对低熔点聚酰胺的结晶和熔融行为进行研究,考察了共聚单体、等温结晶温度和时间对样品结晶和熔融行为的影响。结果表明:经等温结晶后的样品再次升温时,均出现了双熔融峰,且随等温结晶温度的升高或时间的延长,低温熔融峰向高温方向移动,而高温熔融峰则基本不变。等温结晶温度80℃时,两种样品的熔融焓值均较大,并且随结晶时间的延长会变大。X射线衍射结果表明:随着结晶温度的升高或时间的延长,衍射峰变得尖锐,样品的结晶度增大。添加了十二烷基二胺的切片B比添加癸二胺的切片A具有更好的结晶能力,比较适合纺丝加工。     

MCPA6/纳米TiO2原位复合材料的熔融行为

采用差示扫描量热法(DSC)研究了铸型尼龙6(MCPA6)及其纳米TiO2原位复合材料的等温结晶与非等温结晶晶体的熔融行为。结果表明：MCPA6／纳米TiO2原位复合材料等温结晶晶体的熔融行为呈现三重熔融峰，非等温结晶晶体的熔融行为呈现二重熔融峰；其高温熔融峰温随等温结晶温度或降温速率的变化基本不变，而低温熔融峰温则随等温结晶温度的升高或降温速率的减小而提高；纳米TiO2的加入对MCPA6有一定的成核作用，使其熔点提高。     

熔融条件对TPU/尼龙1010共混体系中尼龙1010熔融行为的影响

本文利用差示扫描量热仪DSC研究了熔融温度与熔融时间对聚酯型热塑性聚氨酯弹性体(TPU)/尼龙1010共混体系中尼龙1010熔融行为的影响。不同的熔融温度和熔融时间对TPU/尼龙1010的熔融行为的影响表明,在熔融温度为195℃时,尼龙1010的熔融峰为双峰;在熔融温度为210 oC和225 oC时,熔融峰为单峰;在熔融温度为230 oC时,尼龙1010的熔融双峰逐渐靠拢,TPU含量达到80%时,尼龙1010的熔融峰消失。随着熔融时间的延长,在TPU含量为20%时,尼龙1010的熔融双峰逐渐靠拢变为单峰,在TPU含量为40%和60%时,尼龙1010的熔融峰为单峰,熔融峰位置向低温方向移动,熔融峰温度大幅度降低;当TPU含量达到80%,尼龙1010的熔融峰消失。     

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。     

PVDC涂覆膜的固化条件与冷结晶行为

通过调节聚偏氯乙烯涂覆膜固化时的温度梯度和时间梯度,研究了成膜过程中温度制度和时间制度对其结晶性能的影响。结果表明:固化温度为60℃时,链段运动较难,结晶能力差,结晶行为明显依赖于固化时间。升温过程中冷结晶峰显著,表明结晶不充分,70℃时,冷结晶峰依然存在;80～85℃时,5 min左右可形成完善结晶,冷结晶峰消失,且主熔融峰焓高于固化温度为60～70℃时的,结晶行为理想。     

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。     

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。     

熔融共混PPS／PEEK中PPS组分的结晶行为

采用熔融共混法制备结晶／结晶共混体系ＰＰＳ／ＰＥＥＫ，并用差示扫描量热法研究了不同ＰＥＥＫ含量和不同ＰＥＥＫ粒径对ＰＰＳ／ＰＥＥＫ共混物中ＰＰＳ组分结晶行为的影响。随ＰＥＥＫ含量的增加ＰＰＳ的结晶温度提高，结晶峰宽增加。这是由于在降温过程中ＰＥＥＫ先结晶，可充当ＰＰＳ熔体结晶的异相晶核，使ＰＰＳ结晶温度提高，且随着ＰＥＥＫ含量增加，异相晶核密度增大，但ＰＥＥＫ晶区的存在阻碍了ＰＰＳ的结晶生长过程，     

Crystallization and melting behaviors of poly(aryletheretherketone) (PEEK) on origin of double melting peaks

The crystallization and melting behaviors of poly(aryletheretherketone) (PEEK) films were investigated, using differential scanning calorimetry and metallurgy concepts. The shape of the time–temperature–transformation (TTT) diagram, established for PEEK, results from both nucleation and growth phenomena. The double melting behavior exhibited by isothermally crystallized PEEK samples are discussed through the TTT diagram and the influence of the thermal history in the molten state. The upper melting peak arises first and the lower melting peak is developed later. The location of such a second endotherm is shifted toward the higher temperature with increasing either the crystallization temperature or the annealing time while the location of the upper melting peak seems to be unchanged. The double melting behavior is related to a bimodal distribution in size and/or perfection of lamellae developed in a two-step crystallization. With increasing temperature and/or annealing time in the molten state, the pattern of the endothermic curves is modified. The observed changes are discussed through two origins: the progressive disappearance of remnants of the former crystals and a thermal degradation leading to a cross-linking of the polymer. © 1994 John Wiley & Sons, Inc.     

Effect of blending on the multiple melting behavior of polyphenylene sulfide

The effects of melting time (t_melt) and annealing time (t_a) at a temperature closer to the melting point of polyphenylene sulfide (PPS) on the multiple melting behavior of neat PPS, and PPS component in their blends have been investigated by differential scanning calorimetry (DSC). It is found that double endotherm peak of PPS annealed at 275°C for less than three hours is different from that annealed for twelve hours. Double endotherm peak of PPS in PEEK/PPS blends shifts to lower temperature, and the intensity of the upper melting peak decreases significantly by addition of polyether ether ketone (PEEK). An additional third melting peak could be observed. The temperature of third melting peak is above 310°C and increases as the t_a and PEEK content are increased. For PEK-C/PPS blends, the lower and upper melting temperatures of the PPS component are higher than that of neat PPS annealed at 275°C for twenty-three hours. © 1996 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1001–1008, 1997     

Effects of mechanical drawing on the structure and properties of peek

This study examines the effects of crystallinity and temperature on the mechanical properties of PEEK. Crystallinity in PEEK Increases with annealing temperature up to a maximum of 28 percent with a melting point at 335°C. A minor melting peak also occurs about 10°C above the annealing temperature. In cold drawing the samples exhibited a yield stress and necking followed by homogeneous drawing. The yield stress increases with crystallinity, but there is no change in the modulus. The extension in the necking process also increases with crystallinity, however there is only a slight increase in extension-to-break since necking is compensated by the final amount of homogeneous drawing. The yield stress of PEEK when drawn at T_g (145°C) is significantly lower than at room temperature indicating a reduction in mechanical properties at temperatures approaching T_g. After mechanical drawing the minor melting peak disappears and on heating the material undergoes cold crystallization near the onset of T_g. There is evidence that this minor crystalline component might contribute to the yield stress changes with annealing history. Cold drawing induces crystallization of amorphous PEEK but decreases crystallinity and generates microscopic voids in crystalline PEEK, The various effects of crystallinity on mechanical properties could be important in determining the stress response of PEEK as the matrix in composites.     

Influence of molecular weight on rheological,thermal, and mechanical properties of PEEK

This study focuses on the influence of molecular weight on the rheological, thermal, and mechanical behavior of poly(ether‐ether‐ketone) (PEEK), a semicrystalline high‐performance polymer. The results show that the molecular weight of PEEK has significant influence on its rheological, thermal, and mechanical behavior. It was found that PEEK has the unique characteristic of two shear‐thinning regions. The shear viscosity and the stress relaxation time of PEEK increase significantly as molecular weight increases. In general, the Cox‐Merz rule is valid for all grades of PEEK. As molecular weight increases, the melting temperature of PEEK decreases slightly, but its isothermal and nonisothermal crystallization temperatures drop dramatically. As molecular weight increases, the crystallinity, the crystallization rate, and the magnitude of crystallization activation energy decrease. The crystallization kinetics study indicates that PEEK tends to form spherical crystalline structures, regardless of its molecular weight. As molecular weight increases, the tensile strength at yield, the tensile modulus, and the flexural modulus of PEEK decrease slightly, whereas the tensile strength at break, the tensile strain at break, the modulus of toughness, and the impact strength of PEEK increase significantly. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

星形聚L-乳酸的制备及性能研究

以L-乳酸为原料,季戊四醇为支化剂,采用SnCl2·2H2O／TSA复合催化剂合成了星形支化聚L-乳酸,并采用DSC、偏光显微镜研究了星形聚L-乳酸的结晶和熔融行为．探讨了星形聚乳酸的热降解性能。DSC研究结果表明,熔融缩聚制备的星形聚L-乳酸在升温过程中基本观察不到冷结晶峰,只出现一个熔融峰。经过等温结晶处理后的星形聚L-乳酸再次升温时出现双熔融峰．其中低熔融峰的峰值温度（Tm（L））与等温结晶温度的对数值成线性增长关系,而高熔融峰的峰值温度（Tm（H））与等温结晶温度基本无关。     

几种医用聚丙烯专用料的研究

研究了几种医用聚丙烯专用料的力学性能、流变性能、结晶特性及其熔融特性。结果表明：XF1800的屈服应力、断裂伸长率和缺口冲击强度都较SPG163、SPG164高，并在拉伸过程中表现出典型的应变硬化，而SPG163、SPG164则表现为显著的冷拉现象。XF1800的熔体流动速率最低，流动性较差，而SPG164的熔体流动速率最高，加工流动性最好。转矩流变仪测试表明三种料的平衡时间相差不大，但SPG163和SPG164相对于XF1800稍长；平衡状态下，XFl800的表观粘度最大，整个过程的加工能耗也最大，SPG164最小。瓶坯吹塑成瓶后，三种物料的晶体熔融起始温度Tmo、熔融峰温Tmp均有所上升，而晶体熔融半峰宽都大幅下降，结晶的规整性提高，结晶度也有所提高，表明瓶坯在吹塑成瓶的过程中结晶结构发生了显著的变化，可能还伴有晶型的转变。非等温结晶过程中，SPGl63和SPGl64的结晶峰宽度、结晶峰位置几乎相同，结晶温度T。(103℃)高于XF1800(98．5℃)，表明XFl800的结晶速率较慢，结晶完成的时间较长，结晶能力较差。     

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