GCHD改性PET共聚酯的非等温结晶动力学

以对苯二甲酸(PTA)和乙二醇(EG)为主要原料、戊二酸环氧环己烷二酯二醇(GCHD)为第三单体,采用直接酯化熔融缩聚法,制备了GCHD改性聚对苯二甲酸乙二酯(PET)共聚酯(PEGHT)。利用差示扫描量热仪测定了PET及PEGHT在不同降温速率下的降温曲线,并且采用Jeziorny方法分析了PEGHT的非等温结晶动力学。结果表明,随着降温速率的提高,PET及PEGHT的结晶温度降低,结晶范围增大,半结晶时间减小;在相同降温速率下,与PET相比,PEGHT的结晶温度降低,结晶范围增大,半结晶时间减小,非等温结晶速率常数增大,这表明,GCHD添加后,PET的结晶能力降低,结晶速率增大;PET及PEGHT的n值均为1～3,并且变化较小,这表明,GCHD对PET的成核机理和生长方式的影响均较小。     

含氟PET的非等温结晶动力学

通过分子设计,在聚对苯二甲酸乙二酯(PET)大分子主链上同时引入耐热性的芳杂酰亚胺环和含氟基团。以六氟二酐和氨基十一酸为原料,通过热环化反应合成酰亚胺二酸,再用制备的酰亚胺二酸单体按照不同配比和对苯二甲酸二甲酯、乙二醇按一定比例调节投料比进行酯化缩聚反应,合成一系列含氟PET。利用差示扫描量热(DSC)法研究了聚合物非等温结晶行为,发现纯PET的结晶能力最强,随着含氟量的增加,结晶能力减弱。采用Jeziorny法分析了纯PET和含氟PET的非等温结晶动力学,发现结晶速率常数随着含氟链段的加入而减小,表明含氟链段的加入降低了PET的结晶能力。     

PET/BaSO4共混材料非等温结晶动力学的研究

通过熔融共混方法,将经不同表面处理的BaSO4添加到聚对苯二甲酸乙二醇酯中,制备出了3种PET/BaSO4共混材料。采用SEM对BaSO4在PET基体中的分散状态进行了观察,并用Jeziorny、Ozawa和Mo方法对添加有不同表面改性的PET/BaSO4共混材料以及纯PET进行了非等温结晶动力学分析。分析结果表明,添加BaSO4后,PET的结晶速率大大提高,尤其是经无机硅铝包覆的BaSO4,促进PET结晶的效果更好。Ozawa方法在分析PET/BaSO4共混材料的非等温结晶时偏差较大;而Jeziorny方法虽然也有一定的偏差,但能很好地分析主结晶过程;Mo方法能很好地分析非等温结晶过程。     

NPG改性PET薄膜热收缩性能的研究

运用自制的反应装置，通过加入第三单体的方法对聚对苯二甲酸二醇酯（PET）进行了共聚改性，研究了第三单体新戊二醇（NPG）用量对PET玻璃化转变温度Tg、结晶熔融行为和热收缩性能的影响，同时对拉伸工艺对薄膜收缩率的影响也进行了研究。结果表明，通过NPG共聚改性的PET的结晶能力随NPG用量的增加而降低，热收缩能力有了明显的提高；无定型区增大，获得了在通常情况下不能结晶的PET无定型材料，从而使改性PET薄膜在拉伸时保持较高的取向度，并在高于其Tg时发生解取向热收缩；拉伸温度、拉伸倍数等拉伸工艺对于聚酯薄膜的热收缩率有着显著的影响。     

共聚改性聚酯的等温结晶动力学研究

<正> 一 引 言 高聚物的结晶性能,对于其加工过程及制品性能是十分重要的。因此,高聚物的结晶动力学和热力学至今仍是很重要的的课题。聚对苯二甲酸乙二酯(PET)的结晶动力学研究,已有许多文献作了详细报导。近来,对PET纤维进行了各种目的的改性,其中以改进染色性为目的的共聚改性,是在PET大分子链中引入各种改性剂以破坏其分子链的规整性,或者引入与染料分子有亲和     

二苯基硅二醇简单而经济的合成方法

用二苯基二氯硅烷(Ph2SiCl2)在氢氧化钠水溶液中直接水解合成二苯基硅二醇[Ph2Si(OH)2],研究了反应条件对产率的影响。结果表明,在氢氧化钠浓度为5%,反应温度0~2℃,反应时间4 h的条件下,二苯基硅二醇的产率为92%,与文献报道值相当。     

纳米SiO2对聚对苯二甲酸乙二酯结晶行为及性能的影响

采用六甲基二硅氮烷改性纳米SiO2,并在聚对苯二甲酸乙二酯合成过程中加入改性纳米SiO2制备PET/SiO2纳米复合材料。采用红外光谱、热分析和扫描电镜表征了纳米SiO2粒子的改性效果,并就SiO2加入量对PET结晶行为、力学性能及电学性能的影响进行了研究。结果表明,纳米SiO2经六甲基二硅氮烷处理后,团聚减少,并且能较好地分散于PET中。当纳米SiO2含量为1 %时,结晶速度最快。当纳米SiO2含量为0.1 %时,PET的拉伸强度、弯曲强度和冲击强度分别提高了12.8 %、14 %和11.4 %;纳米SiO2含量在0.25 %~1 %时,随其含量的增加,PET的介电常数逐渐减小,体积电阻率逐渐增大。     

PET/硅灰石纤维复合材料的结晶动力学研究

聚对苯二甲酸乙二醇酯(PET)性能十分优异,使用范围十分广泛,但是由于结晶速度过慢,需要对其进行改性。本实验先将硅灰石纤维制成母料,再用母粒对聚对苯二甲酸己二醇酯(PET)进行改性,对硅灰石纤维改性PET复合材料进行了差示扫描式量热(DSC)测试,并使用莫氏理论对其非等温降温结晶过程进行了动力学分析。     

PET热收缩薄膜的制备

研究了间苯二甲酸(IPA)和新戊二醇(NPG)改性聚对苯二甲酸乙二酯(PET)的性能、干燥制膜工艺及薄膜热收缩性能.结果表明:改性PET的结晶速率及结晶能力均降低,加入IPA影响程度较大;干燥改性PET宜采用真空转鼓方式,采用低温快速冷却方式单向拉伸,可获得高收缩率的PET热收缩薄膜;在玻璃化转变温度附近薄膜的热收缩率变化最大,NPG改性PET薄膜在热水中的热收缩率可达50%.     

抗菌防霉材料ZnO/PET的等温结晶动力学及动力学预测

使用差示扫描量热仪对抗菌防霉材料纳米氧化锌/聚酯(ZnO/PET)的共混物和纯PET进行等温结晶动力学对比分析和动力学预测,结果发现:相比于纯PET,ZnO/PET具有更好的结晶能力。该研究结果有助于指导ZnO/PET纤维加工过程中的工艺参数调整。     

Non-isothermal Crystallization Behavior of Poly(ethylene terephthalate)/Poly(trimethylene terephthalate) Blends

Summary Non-isothermal crystallization behavior of Poly(ethylene terephthalate)/Poly(trimethylene terephthalate) blends was investigated by XRD and DSC. By XRD spectra analysis, it could be concluded that PET and PTT crystals coexisted. They did not form the cocrystals due to different chemical structures. The Avrami equations modified by Jeziorny and Ziabicki’s kinetic crystallizability analysis were employed to describe the non-isothermal crystallization process of PET/PTT blends. The results suggested that the entanglement of the two polymer chains decrease the crystallizability of PET and PTT in blend. The crystallization activation energies of the blend evaluated by the Friedman method also indicated that the presence of two components in the blends hinders the crystallization process of both components.     

PTT非等温结晶动力学研究

采用差示扫描量热仪对PTT进行非等温结晶研究。利用不同动力学模型对其结晶过程进行处理, 并将PTT与PET及PBT的非等温结晶过程进行对比。结果表明:Jeziorny方程和Ozawa方程都可以很好的 描述PTT,PET,PBT的非等温结晶过程;采用结合Avrami方程和Ozawa方程的处理方法,得到了3种聚酯的 结晶速率的大小关系:PBT>PTT>PET。通过计算Ziabicki结晶能力参数,得到3种聚酯的结晶能力的顺序 为:PBT>PTT>PET。     

Antinucleating action of polystyrene on the isothermal cold crystallization of poly(ethylene terephthalate)

The effect of polystyrene (PS) on the kinetics of the cold crystallization of poly(ethylene terephthalate) (PET) was thoroughly investigated. The PET/PS blends were essentially immiscible, as observed by dynamic mechanical thermal analysis, which showed two distinct glass‐transition temperatures, and by scanning electron microscopy. The neat PET and its blends were isothermally cold‐crystallized at various temperatures, and the kinetic parameters were determined with the Avrami approach. PET and its blends presented values of the Avrami exponent close to 2, and the kinetic constant increased with the crystallization temperature increasing. For all the crystallization temperatures studied, the presence of only 1 wt % PS significantly reduced the rate of cold crystallization of PET. A further increase in the PS concentration did not show any significant influence. The blends presented higher values of the activation energy for cold crystallization, which was estimated from Arrhenius plots. The equilibrium melting temperature of neat PET was determined on the basis of the linear Hoffman–Weeks extrapolative method to be ～ 255°C. This value decreased in the presence of PS, and this suggested limited solubility between PET and PS. From the spherulitic growth equation proposed by Hoffman and Lauritzen, the nucleation parameter was obtained, and it was shown to be higher for the neat PET than for the blends. Moreover, a transition of regimes (I → II) was observed in both PET and its blends. From the investigations conducted here, it is clear that PS in small amounts causes a reduction in the rate of PET crystallization, acting as an antinucleating agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

水溶性聚酯的结晶性能研究

研究了水溶性聚酯(W SPET)切片的结晶性能,并与常规聚酯(PET)切片相对比。结果表明W SPET切片与PET切片具有相同的非等温结晶行为,在非等温条件下的结晶机理以异相成核为主,在有限的三维体积中生成球晶,但W SPET切片的结晶速率明显慢于PET切片,结晶能力明显弱于PET切片。     

Crystalline morphology and isothermal crystallization kinetics of poly(ethylene terephthalate)/clay nanocomposites

A poly(ethylene terephthalate) (PET)/montmorillonite clay nanocomposite was synthesized via in situ polymerization. Microscopic studies revealed that in an isothermal crystallization process, some crystallites in the nanocomposite initially were rod‐shaped and later exhibited three‐dimensional growth. The crystallites in the nanocomposite were irregularly shaped, rather than spherulitic, being interlocked together without clear boundaries, and they were much smaller than those of neat PET. With Avrami analysis, the isothermal crystallization kinetic parameters (the Avrami exponent and constant) were obtained. The rate constants for the nanocomposite demonstrated that clay could greatly increase the crystallization rate of PET. The results for the Avrami exponent were consistent with the observation of the rodlike crystallites in the PET/clay nanocomposite during the initial stage. Wide‐angle X‐ray scattering and Fourier transform infrared studies showed that, in comparison with neat PET, the crystal lattice parameters and crystallinity of the nanocomposite did not change significantly, whereas more defects may have been present in the crystalline regions of the nanocomposite because of the presence of the clay. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1381–1388, 2004     

聚对苯二甲酸丙二醇酯的非等温结晶动力学研究

采用DSC研究了聚对苯二甲酸丙二醇酯(PTT)在不同等速降温速率下的结晶过程,并利用由等温Avrami方程推导得到的两种不同的等速降温非等温结晶方程,研究了其结晶动力学,得出PTT的成核方式为异相成核,同时利用拟和法计算了PTT的结晶能力,发现在同等条件下PTT的结晶能力大于PET。     

苯乙烯-甲基丙烯酸钠离聚物的合成及其对PET结晶行为的影响

采用溶液法制备苯乙烯-甲基丙烯酸钠(SMA-Na)离聚物,研究其对聚对苯二甲酸乙二酯（PET）的结晶及熔融行为的影响。结果表明：SMA-Na是PET的良成核剂,加入1wt %的苯乙烯-甲基丙烯酸钠使PET的熔融结晶温度（Tmc）提高了17.9 ℃,冷结晶温度(Tcc)降低了17.3℃,显著的提高了PET在高温区和低温区的结晶速度。加入离聚物,使得PET球晶变得更加细化完善。     

Effect of nano-nucleating agent addition on the isothermal and nonisothermal crystallization kinetics of isotactic polypropylene

Using differential scanning calorimetry (DSC) technique, a comparative study has been made of the isothermal and nonisothermal crystallization kinetics of nonnucleated isotactic polypropylene (iPP) and of nucleated iPP with 0.5 wt% of single-walled carbon nanotubes (SWCNTs) as a nucleating agent. The Avrami exponents (n) of iPP and nucleated iPP are close to 3.0 for isothermal crystallization. These results indicate that the addition of nucleating agents did not change the crystallization growth patterns of the neat polymer and that crystal growth was heterogeneous three-dimensional spherulitic. The results show that the addition of SWCNTs can shorten the crystallization half-time (t _1/2) and increase the crystallization rate of iPP. In the nonisothermal crystallization process, the Ozawa model failed to describe the crystallization behavior of nucleated iPP. The Cazé–Chuah model successfully described the nonisothermal crystallization process of iPP and its nanocomposite. A kinetic treatment based on the Ziabicki theory is presented to describe the kinetic crystallizability, in order to characterize the nonisothermal crystallization kinetics of iPP and nucleated iPP. Polarized light microscopy (PLM) experiments reveal that SWCNTs served as nucleating sites, resulting in a decrease of the spherulite size.     

Blends of thermoplastic polyesters with amorphous polyamide. I. Thermal and crystallization behavior

The thermal and crystallization behavior of blends of three thermoplastic polyesters with different degrees of crystallizability, with an amorphous aromatic polyamide is reported. The thermoplastic polyesters used in the investigation were poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET) and a co-polyester of 1,4 cyclohexane-dimethanol, ethylene glydol and terephthalic acid (PETG). The blends exhibited a single glass transition temperature indicating mlseibility in the amorphous phase. The results of thermal analysis indicated that the crystallization of all the three polyesters is facilitated in the molten phase as a result of blending. The blending significantly Increased the degree of crystallinity of PET, but there was no change in the crystallinity of PBT. It is thus observed that the extent of change in both the crystallization rate and the degree of crystallinity of polyesters depend on the inherent crystallizability of the individual polyester.