丙烯/1-丁烯无规共聚物与丙烯/乙烯抗冲共聚物的对比研究

对丙烯/1-丁烯无规共聚物(PPB)与丙烯/乙烯抗冲共聚物(PPE)的结晶行为进行对比,在等温结晶时,通过相对结晶度随时间的变化关系、等温结晶曲线等研究,表明丙烯/1-丁烯无规共聚物结晶速率明显低于丙烯/乙烯抗冲共聚物,同时丙烯/乙烯抗冲共聚物的等温结晶速率随乙烯单元含量增加没有明显降低。根据Avrami方程计算了共聚物的结晶活化能,证明丙烯/1-丁烯无规共聚物的结晶能力较丙烯/乙烯抗冲共聚物低。扫描电镜分析丙烯/1-丁烯无规共聚物在丁烯单元摩尔分数2.39%时没有韧性拉伸,而丙烯/乙烯抗冲共聚物在乙烯单元摩尔分数3%时出现韧性拉伸。     

丙烯/1-丁烯无规共聚树脂等温结晶动力学研究

采用本体聚合方法合成了丙烯/1-丁烯无规共聚树脂,通过DSC研究了丙烯/1-丁烯无规共聚物的等温结晶动力学。根据Avrami方程求出了各个结晶温度下的结晶动力学参数K(T)、 n、t1/2,以及样品的结晶活化能。结果表明,随着结晶温度的升高,同一样品的结晶速率逐渐下降,说明样品的结晶是依热成核控制为主;Avrami指数 在3~4之间,表明共聚物晶体的生长方式为三维球状生长。在同一结晶温度条件下,随着共聚物中1-丁烯单元含量的增加,晶体的成核和结晶速率均下降,结晶活化能增加,共聚物中1-丁烯单元含量对结晶速率的影响很大。     

丙烯/丁烯-1共聚透明聚丙烯的生产开发

文章阐述了生产透明聚丙烯的方法。介绍了丙烯/丁烯-1共聚透明聚丙烯PPR-MT18-S的开发和生产过程,讨论了丙烯/丁烯-1无规共聚物与丙烯/乙烯无规共聚物物理性能比较,结果表明丙烯/丁烯-1无规共聚物更适合于食品或药品容器、器具。     

偏氟乙烯－六氟丙烯共聚物溶剂浇铸膜的非等温结晶动力学行为

利用示差扫描量热法(DSC)研究偏氟乙烯-六氟丙烯(PVDF-HFP)共聚物溶剂成膜前后的非等温结晶动力学,结果表明,PVDF-HFP共聚物的结晶对降温速率有一定的依赖关系,成膜后的共聚物与成膜前的共聚物对比发现,成膜后的共聚物的结晶温度升高,结晶速率加快,结晶时间t1/2缩短.用Jeziomy法处理非等温结晶过程较理想.Jeziomy法求出的结晶指数n的值在3～4之间,成膜前后的结晶速率常数kc影响较小.n和kc随降温速度的增大而增大,并且成膜后的共聚物的n和kc大于加工前的树脂的n和kc.Kissinger方法计算的PVDF-HFP共聚物成膜前后的结晶活化能分别为119.97kJ/mol和168.29kJ/mol.     

SEBS-g-MAH对聚乙烯等温及非等温结晶动力学的影响

利用差示扫描量热法结合Avrami方程研究了苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物接枝马来酸酐(SEBS-g-MAH)对线型低密度聚乙烯(LLDPE)等温及非等温结晶动力学的影响。结果表明,热塑性弹性体SEBS及其接枝物的加入阻碍了LLDPE分子链的规则排列,影响了链段在结晶扩散迁移规整排列的速度,使得结晶速率变慢,对LLDPE晶体生长起了抑制作用;LLDPE/SEBS-g-MAH共混体系的半结晶时间t1/2和结晶活化能E明显增大,Avrami指数n对结晶温度有依赖性,kn值随温度的升高而减小。通过Jeziorny法对非等温结晶过程进行处理,试样的Avrami指数n值均在1.1~1.5,表明LLDPE的结晶成核机理和生长方式没有改变。     

丙烯/1-丁烯共聚物/无机物复合材料的性能研究

用无水硫酸钙/二氧化硅复合无机物对丙烯/1-丁烯共聚物进行填充改性,研究了丙烯/1-丁烯共聚物/无机物复合材料的物理性能、结晶熔融性能.结果表明:与丙烯/1-丁烯共聚物相比,改性后复合材料的弯曲模量和维卡软化温度均升高,冲击强度和熔体流动速率均下降,注塑样品收缩率的各向异性减小,结晶峰温度和结晶起始温度均升高,结晶温度...     

无规抗冲共聚聚丙烯的非等温结晶动力学

在Spheripol工艺中试装置上制备了丙丁无规抗冲共聚聚丙烯（记作PP-1）和乙丙丁无规抗冲共聚聚丙烯（记作PP-2），对两种聚丙烯的非等温结晶行为进行了研究，针对无规抗冲共聚聚丙烯实际生产过程中的结晶特点，分别结合Caze法和Mo法提出的理论对非等温结晶动力学Ozawa模型进行了修正。结果表明：采用修正过的两种方法更加符合无规抗冲共聚聚丙烯实际生产过程中的非等温结晶行为。采用Caze法修正Ozawa模型后求出的PP-1和PP-2的Avrami指数分别为2.44,2.37，说明乙烯单体的引入并不会使PP-1的成核机理和生长方式发生改变。采用Mo法修正Ozawa模型后求出的动力学参数F(T)在同一相对结晶度下PP-1小于PP-2，表明在同一时间内PP-2要达到某一结晶度所需冷却速率更大；采用Kissinger法计算的PP-1和PP-2的结晶活化能分别为11.12,14.14 kJ/mol，进一步证实了上述结果。     

尼龙612/6共聚物的表征与非等温结晶动力学研究

以尼龙612盐和己内酰胺为原料,采用熔融聚合的方法合成了尼龙612/6共聚物,采用傅里叶红外光谱仪(FTIR)、核磁共振氢谱仪(1HNMR)、偏光显微镜(PLM)对其相关结构进行表征,并分别用Jeziorny修正的Avrami方程、Ozawa方程、莫志深法进行非等温结晶动力学分析。结果表明:尼龙612结晶过程为二次成核,成核后沿着晶核二维盘状生长;而尼龙612/6共聚物的结晶过程为一次均相成核,晶核形成后沿晶核二维盘状与三维球状生长;莫志深法分析结果对应参数a基本保持一致,说明Avrami指数n与Ozawa指数m之间确实存在一定的数量关系,F(T)的变化表明,要在单位时间内达到更高的结晶度需提高降温速率,同时相同结晶度下尼龙612的结晶速率远大于尼龙612/6共聚物;采用Kissinger方程计算得出尼龙612及其共聚物的非等温结晶活化能ΔE分别为-433.29 kJ/mol、-94.12 kJ/mol。     

1-丁烯-丙烯共聚物结构与性能研究

考察了1-丁烯-丙烯共聚物(B-P)的结晶性能、力学性能和流变行为,并与高全同聚1-丁烯(i-PB)进行了结构与性能的对比。结果表明:少量丙烯的引入,破坏了1-丁烯链段的规整排列,造成结晶度降低,力学性能下降。B-P的剪切速率增加到某一临界值时,材料内部结构发生改变,1-丁烯链段和丙烯链段同时开始运动,发生了剪切变稠,共聚物黏度变大,不易成膜。     

PAN/DMSO溶液等温结晶行为的研究

利用广角X射线衍射(WAXD)的方法研究了聚丙烯腈/二甲基亚砜(PAN/DMSO)溶液的等温结晶行为。结果表明:溶液中PAN分子链以无规线团的形态存在;一定结晶温度下,PAN的结晶度随着时间的延长而增大,且前期结晶成核速率大于中后期晶粒生长速率;提高结晶温度,PAN结晶速率增加,结晶更为完善,结晶完成后,结晶度可达80.5%;PAN/DMSO溶液的等温结晶过程分为4个阶段,即无定形态、短程有序的螺旋构象、长程有序结构及完善的晶态结构。     

Triple crystallization behavior of fractionated ethylene/α-olefin copolymers of different catalyst type

Non-isothermal crystallization processes in fractions of Ziegler-Natta (ZN) and single site (SS) based ethylene/1-butene and ethylene/1-hexene copolymers have been studied by differential scanning calorimetry (DSC). Fractionation of used copolymers was done according to molar mass (MM) and composition (comonomer content). It was observed in DSC scans that for fractions with high MM (larger than 10 kg/mol) in addition to the main high-temperature crystallization peak (HTCP), a very-low temperature crystallization peak (VLTCP) is present at temperatures in between 60–75 °C. Such peak is absent for the first fractions having very-low MM. The partial crystallinity and peak temperatures, obtained from VLTCP, increase with MM and level off at MM around 60–100 kg/mol. It was found that the crystallinity as related to the area of the VLTCP is catalyst type dependent, and is higher for the SS catalyst compared to the ZN. Peak temperature of VLTCP linearly decreases with increasing comonomer content at fixed MM while the partial crystallinity practically does not change with comonomer content.     

Effect of cooling rate on melt-crystallization of random propylene-ethylene and propylene-1-butene copolymers

Summary  The effect of variation of the rate of cooling on melt-crystallization of random copolymers of isotactic polypropylene with low amount of either ethylene or 1-butene is evaluated using X-ray techniques, atomic force microscopy, and calorimetry. Slow non-isothermal melt-crystallization mainly results in formation of monoclinic α-crystals of lamellar geometry. The presence of comonomers leads to a decrease of the degree of crystallinity, and of the thickness of lamellae. These changes are proportional to the concentration of co-units, and are more distinct in propylene-ethylene copolymers. Rapid cooling of propylene-1-butene copolymers leads to formation of non-lamellar mesomorphic domains, independent of the concentration of co-units within the investigated range of concentrations. In quenched propylene-ethylene copolymers, in contrast, the formation of mesomorphic structure partially is replaced by formation of monoclinic α-crystals of still non-lamellar geometry.     

PP/空心玻璃微珠复合材料非等温结晶研究

采用熔融共混挤出的方法,制备了聚丙烯(PP)/空心玻璃微珠(HGB)复合材料,用差示扫描量热法研究了PP和PP/HGB复合材料的非等温结晶过程,并通过Jeziorny和莫志深方程研究了非等温结晶动力学。结果表明,随降温速率的增大,PP和PP/HGB复合材料的结晶峰温和结晶度降低,结晶速率增大;HGB的加入降低了PP的结晶速率。     

Morphological and kinetic partitioning of comonomer in random propylene 1-butene copolymers

The partitioning of the 1-butene co-unit between crystalline and non-crystalline regions of random, homogeneous propylene 1-butene copolymers (PB) has been studied by WAXD, ¹³C NMR, and FTIR in a series of copolymers with a concentration of 1-butene ranging from 2 to ～ 20 mol%. A partial inclusion of the 1-butene co-unit in the crystallites is identified by the expansion of the unit cell, and quantified by extracting ¹³C NMR spectra of the crystalline regions. For slowly cooled copolymers, about 30% of the chain’s 1-butene co-units are incorporated into the crystallites. Analyses of FTIR absorbances associated with crystalline 1-butene provide additional quantitative information on the morphological partitioning of the co-unit and give evidence to support that the incorporation of the comonomer into the crystalline regions is controlled by crystallization kinetics. The presence of the comonomer in the crystalline region affects the observed vibration of the most sensitive iPP 3/1 regularity bands associated with the evolution of crystallites, i.e. 841 cm^?1 (12 isotactic units). The frequency of this band shifts toward higher values with increasing comonomer and with increasing undercooling, in support of an increasing concentration of entrapped crystalline 1-butene. The frequency shift is absent in copolymers with co-units that are excluded from the crystalline regions, such as the 1-octene comonomer.     

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。     

PBT非等温结晶动力学

用差示扫描量热法研究聚对苯二甲酸丁二酯（PBT）的非等温结晶动力学，并分别用Ozawa,Jeziorny和考虑综合因素法来处理PBT的非等温结晶数据。结果表明，PBT非等温结晶过程与Ozawa动力学方程相吻合，但不符合用Jeziorny方法处理的Avrami动力学方程；综合考虑温度和结晶程度对聚合物结晶速度的影响。PBT非等温结晶过程符合结晶动力学方程。     

PBT/PTT合金的非等温结晶行为

采用差示扫描量热法(DSC)研究了聚对苯二甲酸丁二酯(PBT)/聚对苯二甲酸丙二酯(PTT)合金的非等温结晶动力学.随着降温速率的增大,PBT/PTT合金的结晶峰温均降低,结晶峰均加宽.采用Jeziorny法、莫志深法和Flyn-Wall-Ozawa法分析非等温结晶过程,Jeziorny法能够描述PBT/PTT合金的初期结晶过程,对后期结晶存在一定偏差,各PBT/PTT合金的结晶维数变化不大;莫志深和Flyn-Wall-Ozawa法能很好地描述PBT/PTT合金的非等温结晶过程,随PTT含量增加,由Flyn-Wall-Ozawa法求得PBT/PTT合金的活化能呈增加趋势.相对结晶度为0.5,m(PBT)/m(PTT)分别为90∶10,70∶30,50∶50时,PBT/PTT合金的活化能分别为-201.9,-116,0,-66.6 kJ/mol;相对结晶度为0.5时,m(PBT)/m(PTT)为50∶50的合金活化能比PTT(-77.4 kJ/mol)还高.     

Effects of oxidative functionalized and aminosilanized carbon nanotubes on the crystallization behaviour of polyamide-6 nanocomposites

The purpose of this study is to investigate effects of oxidative functionalized and aminosilanized carbon nanotubes on the (1) isothermal and (2) non-isothermal crystallization kinetics of polyamide-6 by DSC analyses, and (3) crystal structure of injection molded specimens by XRD analyses. Nanocomposites were compounded by using melt mixing technique via twin screw extrusion. Due to basically very effective heterogeneous nucleation effect, both increasing amount and surface functionalization of carbon nanotubes by oxidation and aminosilanization resulted in higher relative crystallinity for all three cases. The increases were as much as 40 % for the isothermal and non-isothermal crystallization, and it was up to more than two times in the injection molding. Crystallization parameters and Avrami constants indicated that crystallization rate increases in isothermal crystallization while it decreases in non-isothermal crystallization due to the delayed conformational mobility of polymer chains via physical hindrance of carbon nanotubes. Parameters also revealed that growth mechanism of crystallites might change during isothermal crystallization while there was no significant change during non-isothermal crystallization. XRD deconvolution analyses indicated that during injection molding, due to the constraints of carbon nanotubes only α-crystal structure was formed.