Crystallization and crosslinking of polyamide‐1010 under elevated pressure

The structure and thermal properties of polyamide‐1010 (PA1010), treated at 250°C for 30 min under pressures of 0.7–2.5 GPa, were studied with wide‐angle X‐ray diffraction (WAXD), infrared (IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Crystals were formed when the pressures were less than 1.0 GPa or greater than 1.2 GPa. With increasing pressure, the intensity of the diffraction peak at approximately 24° was enhanced, whereas the peak at approximately 20° was depressed. The triclinic crystal structure of PA1010 was preserved. The highest melting temperature of the crystals obtained in this work was 208°C for PA1010 treated at 1.5 GPa. Crosslinking occurred under pressures of 1.0–1.2 GPa. Only a broad diffraction peak centered at approximately 20° was observed on WAXD patterns, and no melting and crystallization peaks were found on DSC curves. IR spectra of crosslinked PA1010 showed a remarkable absorption band at 1370 cm^?1. The N? H stretching vibration band at 3305 cm^?1 was weakened. Crystallized PA1010 had a higher thermal stability than crosslinked PA1010, as indicated on TGA curves by a higher onset temperature of decomposition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2522–2527, 2002     

PA11/PA1010共混物的性能研究

采用熔体共混的方法制备了聚酰胺11/聚酰胺1010(PA11/PA1010)共混物,通过力学性能和差示扫描量热(DSC)测试,研究了PA11/PA1010共混物的力学与结晶性能。测试结果表明:PA1010对PA11同时具有增韧、增强作用;当PA11/PA1010为70/30时,共混物开始出现两个结晶峰和低温熔融峰;共混物的结晶和熔融以PA11为主,兼具有PA11和PA1010的优良性能;断裂伸长率、拉伸强度与缺口冲击强度均达到极大值。     

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。     

Comparison of crystallization behaviors of poly(ε‐caprolactone) in confined environment with that in bulk

The spatial confinement of poly(ε‐caprolactone) (PCL) in the matrix of PMMA was synthesized by insitu polymerization and characterized by WAXD and SEM. The nonisothermal crystallization behavior and the kinetics of PCL in PMMA/PCL (85/15) blend and pure PCL were investigated by means of DSC. Jeziorny and Ozawa's theoretical prediction methods were used to analyze the crystallization kinetics. The melting behavior after cooling was also studied. There was an additional interesting phenomenon of double‐melting peak for pure PCL. Peaks at lower temperature shifted to lower temperature, and peaks at higher temperature did not shift with the increasing cooling rate. This behavior can be due to recrystallization. For the high‐crystallization activity energy and low‐crystallization rate, PCL in bulk would recrystallize during the melting process, and displayed a double‐melting behavior. Under spatial confinement of the rigid PMMA, PCL had much lower crystallization activity energy and had only one melting peak. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

半芳香族耐高温PA10T/1010的非等温结晶动力学研究

利用对苯二甲酸、癸二胺、癸二酸合成了聚对苯二甲酰癸二胺(PA10T)和聚酰胺(PA)1010的共聚物PA10T/1010,通过差示扫描量热法研究了PA10T/1010的非等温结晶动力学,结果表明随着降温速率的增加,结晶温度和熔点不断降低,同时结晶温度的范围变宽,结晶所需时间减少。用Jeziorny法描述了PA10T/1010的非等温结晶过程,发现其结晶过程分为两段,晶体生长方式在前期为二维盘状生长,后期为多维生长。通过Mo法描述了PA10T/1010的非等温结晶动力学,发现降温速率越大,在单位时间内PA10T/1010所能达到的相对结晶度越高。最后通过Kissinger方法计算得到PA10T/1010非等温结晶活化能为–171.47 k J/mol。     

PA6T/1010共聚物热性能研究

以对苯二甲酸、己二胺和癸二酸、癸二胺为原料合成了新型半芳香PA6T/1010共聚物,通过差示扫描量热仪(DSC)、熔点测定仪和热重分析仪(TG)对不同组成PA6T/1010的熔融行为、结晶行为和热稳定性进行了表征。结果表明:当PA6T含量大于40%时,PA6T/1010共聚物的结晶性能明显下降,熔融峰和结晶峰均消失;当PA6T含量为40%时,共聚物共熔点降至165℃;PA6T/1010共聚物的热降解过程为一步降解,热降解温度超过400℃。     

PA6／PET共混物的非等温结晶动力学研究

采用等速升温和等速降温ＤＳＣ法对ＰＡ６／ＰＥＴ共混物的非等温结晶动力学进行了研究。在升温和降温ＤＳＣ相变曲线上，ＰＡ６／ＰＥＴ共混物具有双重熔融峰和双重结晶峰，表明ＰＡ６和ＰＥＴ组分可形成各自的结晶体。给出了各组分的结晶峰温度、结晶峰的半高宽、结晶半时间等表征结晶行为的参数，并讨论了影响结晶的因素。     

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     

Isothermal crystallization kinetics and melting behavior of in situ compatibilized polyamide 6/Polyethylene-octene blends

We developed in situ compatibilization technology to improve the compatibility between polyamide 6 (PA 6) and polyethylene-octene (POE). In the present work, we investigated the isothermal crystallization and melting behavior of PA 6/POE blends using differential scanning calorimetry (DSC). All specimens exhibited double melting peaks at lower temperature and single melting peaks at higher temperature. The Avrami exponent and equilibrium melting temperature were obtained by analysis of DSC experimental data using the Avrami equation and Hoffman-Weeks theory, respectively. It has demonstrated that the crystallization model of PA 6 for all specimens might be a mixture with two-dimensional, circular, three-dimensional growth with thermal nucleation. We further calculated the nucleation parameter (K _g ) from the obtained crystallization kinetics data using Lauritzen-Hoffmann equation. It was found that the K _g values of the compatibilized PA 6 were lower than that of pure PA 6 whereas increased with the increase of POE content, which was related to the better dispersion of POE and the interaction between PA 6 and the in situ formed POE-g-MAH. Additionally, the spherulite morphology was observed by polarized optical microscopy (POM).     

Supercritical carbon dioxide‐induced melting temperature depression and crystallization of syndiotactic polypropylene

This work was aimed at studying supercritical carbon dioxide (scCO₂)‐induced melting temperature depression and crystallization of a syndiotactic polypropylene (sPP). Under scCO₂, the melting temperature of the sPP could be significantly reduced depending on the CO₂ pressure. The scCO₂‐induced crystallization of sPP was investigated using differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy. Two melting peaks were observed in DSC. The one at lower melting temperature referred to the melting of the sPP crystals induced by scCO₂ in its amorphous phase. Its location was shifted to higher temperature, and its area increased with increasing scCO₂ treatment time, temperature, and pressure. The melting peak at higher temperature corresponded to the melting of the sPP crystals that already existed before scCO₂ treatment. Its location and area remained almost unaffected by the scCO₂ treatment. The scCO₂‐induced crystallization was related to scCO₂‐promoted transformation of the mesophase form III of the sPP to the stable form I. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

热塑性聚氨酯对尼龙612熔融结晶行为的影响

用差示扫描量热法（DSC）研究了尼龙612（PA612）和聚酯型热塑性聚氨酯（TPU）共混物的熔融结晶行为。研究表明,尼龙612和TPU之间存在很强的相互作用,这种相互作用阻碍了彼此的结晶。随着TPU含量的增加,PA612的结晶度逐渐减小。PA612含量较大时,TPU本身无法结晶。两者之间的相互作用往熔融态时由于链段扩散容易显得更加明显。     

熔融条件对聚醚醚酮结晶熔融行为的影响

用ＤＳＣ法研究了熔融温度和熔融时间对聚醚醚酮地晶熔融行为的影响。实验表明，聚醚醚酮的结晶峰随熔融延长向高温移动，且峰形变窄，峰的强度增大，继续延长熔融时间，结晶峰降低，峰形变宽；熔融时间延长时，聚醚醚酮的玻璃化转变温度和冷结晶峰温度均提高，熔融峰强度减弱。熔融温度升高时，聚醚醚酮的结晶峰强度减弱，峰宽增强；而冷结晶温度提高。     

Blends of polyamide1010 with unmodified and maleic‐anhydride‐grafted high‐impact polystyrene

The crystallization behaviors, dynamic mechanical properties, tensile, and morphology features of polyamide1010 (PA1010) blends with the high‐impact polystyrene (HIPS) were examined at a wide composition range. Both unmodified and maleic‐anhydride‐(MA)‐grafted HIPS (HIPS‐g‐MA) were used. It was found that the domain size of HIPS‐g‐MA was much smaller than that of HIPS at the same compositions in the blends. The mechanical performances of PA1010–HIPS‐g‐MA blends were enhanced much more than that of PA1010–HIPS blends. The crystallization temperature of PA1010 shifted towards higher temperature as HIPS‐g‐MA increased from 20 to 50% in the blends. For the blends with a dispersed PA phase (≤35 wt %), the T_c of PA1010 shifted towards lower temperature, from 178 to 83°C. An additional transition was detected at a temperature located between the T_g's of PA1010 and PS. It was associated with the interphase relaxation peak. Its intensity increased with increasing content of PA1010, and the maximum occurred at the composition of PA1010–HIPS‐g‐MA 80/20. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 857–865, 1999     

PET/PTT合金非等温结晶行为的研究

采用差示扫描量热仪对熔融共混制备的聚对苯二甲酸乙二醇酯（PET）/聚对苯二甲酸丙二醇酯（PTT）合金的非等温结晶行为进行研究。结果表明,在相同的降温速率时, 随着PTT含量的增加,PET/PTT合金结晶峰温度向低温方向移动,而且当合金中PET与PTT含量接近时,合金样品出现了双重结晶峰;在降温结晶的过程中,随着降温速率的增大,各合金样品结晶峰温度均降低,其结晶峰均宽化;采用Jeziorny法对上述非等温结晶过程进行了分析,分析结果表明,随着降温速率的增大,各合金样品非等温结晶速率常数增加,其Avrami指数在1~5之间,并且逐渐减小。     

Solvent effects on phase transition behavior of canola oil sediment

Differential scanning calorimetry (DSC) was used to study the melting and crystallization behavior of waxy sediment in canola oil and in mixtures (1:1, w/w) of oil and acetone or hexane under dynamic heating/cooling regimes. In the presence of a solvent, the DSC melting peak of sediment shifted to lower temperatures, suggesting that sediment was more soluble in the solvent/oil systems than in oil alone. This effect was greater with hexane than with acetone. The influence of a solvent on crystallization was more complex. With inclusion of hexane, the crystallization temperature of sediment was always lower than that in oil. With acetone, however, the crystallization temperature of sediment was slightly lower at high sediment content, but higher at low sediment content than in oil alone. The differences in melting and crystallization behavior of sediment in canola oil and the solvent/oil systems were attributed to solubility and viscosity effects. Variation in the crystalline solid structures of sediment was not evident from the melting enthalpies associated with the phase transformation.     

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.     

Crystallization of low‐density polyethylene‐ and linear low‐density polyethylene‐rich blends

The crystallization of a series of low‐density polyethylene (LDPE)‐ and linear low‐density polyethylene (LLDPE)‐rich blends was examined using differential scanning calorimetry (DSC). DSC analysis after continuous slow cooling showed a broadening of the LLDPE melt peak and subsequent increase in the area of a second lower‐temperature peak with increasing concentration of LDPE. Melt endotherms following stepwise crystallization (thermal fractionation) detailed the effect of the addition of LDPE to LLDPE, showing a nonlinear broadening in the melting distribution of lamellae, across the temperature range 80–140°C, with increasing concentration of LDPE. An increase in the population of crystallites melting in the region between 110 and 120°C, a region where as a pure component LDPE does not melt, was observed. A decrease in the crystallite population over the temperature range where LDPE exhibits its primary melting peaks (90–110°C) was noted, indicating that a proportion of the lamellae in this temperature range (attributed to either LDPE or LLDPE) were shifted to a higher melt temperature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1009–1016, 2000     

Effect of zirconium dioxide on crystallization and melting behavior of flame sprayed polyamide 1010

The crystallization and melting behavior of flame sprayed Polyamide 1010 (PA1010) containing zirconium dioxide (ZrO₂) were investigated using differential scanning calorimeter (DSC). ZrO₂ has a heterogenous nucleation effect on PA1010, leading to a moderate increase in the crystallization temperature and a decrease in the supercooling temperature. A modified Avrami theory could be successfully used to well describe the early stages of non‐isothermal crystallization of PA1010 and its composite coatings. A study of the nucleation activity, which indicated the influence of the filler on the polymer matrix, revealed that the zirconium dioxide nanoparticles had a good nucleation effect on PA1010. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.     

Non‐isothermal crystallization kinetics of polyamide 1010/montmorillonite nanocomposite

The non‐isothermal crystallization kinetics of pure polyamide 1010 (PA1010) and PA1010/montmorillonite nanocomposite (PA1010/MMT) was investigated by differential scanning calorimetry (DSC) at various cooling rates. The Avrami analysis modified by Jeziorny and a new method developed by Mo can describe the non‐isothermal crystallization process of PA1010 and PA1010/MMT nanocomposite very well. The difference in the value of exponent n between PA1010 and PA1010/MMT nanocomposite suggests that the nano‐size montmorillonite layers act as nucleation agents of PA1010. The values of half‐time of crystallization and crystallization rate coefficient (CRC) show that the crystallization rate of PA1010/MMT nanocomposite is faster than that of PA1010 at a given cooling rate. Polym. Eng. Sci. 44:861–867, 2004. © 2004 Society of Plastics Engineers.     

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。