聚丙烯复合材料的非等温结晶动力学

采用差示扫描量热仪研究了β成核剂和水滑石(LDH)/β成核剂复配的成核剂对聚丙烯(PP)非等温结晶动力学及熔融行为的影响。结果表明:加入成核剂后,PP中晶体分布不均匀且分散度增大。莫志深方法采用F(θ)表征聚合物在单位时间内达到某一结晶度时所需的冷却(或加热)速率,结晶度达到40%时,纯PP的F(θ)为3.82,加入β成核剂的PP的F(θ)为3.30,加入LDH/β成核剂的PP的F(θ)为2.49。与纯β成核剂相比,LDH/β成核剂能更好地提高PP的结晶温度、结晶速率,增强PP的β晶熔融峰,减弱β晶和α晶共存熔融峰和α晶熔融峰。     

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蓄能发光复合材料非等温结晶动力学研究

采用差示扫描量热(DSC)法研究非等温条件下环形对苯二甲酸丁二醇酯(CBT)反应性挤出加工所制聚对苯二甲酸丁二醇酯(PBT)蓄能发光复合材料的结晶行为,分别采用Ozawa,Jeziorny及Mo方程拟合分析复合材料的非等温结晶动力学。结果表明:采用Ozawa及Jeziorny方程所获拟合曲线均不成线性;Mo方程可很好地描述PBT蓄能发光复合材料的非等温结晶过程,拟合所得PBT复合材料的单位时间里体系到达结晶度时的降温速率(F(T))值均较纯PBT的低,且粉体质量分数为15%时,其F(T)值最小,表明加入发光粉体可加速体系的结晶过程,然而在高降温速率下,较高浓度的发光粉体反而会降低体系的结晶速率。     

改性聚乙烯醇的非等温结晶动力学研究

通过差示扫描量热法(DSC)测定了己内酰胺水溶液改性的聚乙烯醇(PVA)降温结晶过程,并用Ozawa方法,Jeziorny方法和莫志深方法分析了改性PVA的非等温结晶动力学。结果表明:随着冷却速率增加,改性体系内起增塑作用的小分子由于其蒸发升华的减缓,改性PVA体系的运动能力增强,结晶度提高;莫志深方法能够较好地解释改性PVA的非等温结晶过程,即在单位时间内达到较大结晶度需较大的降温速率,且随着体系相对结晶度的增加,结晶速率降低。     

Non-isothermal polymer crystallization kinetics and Avrami master curves

The kinetic crystallization model of Avrami is generally accepted as a starting point for the analysis of isothermal polymer crystallization. It is shown in this paper that, in the case of non-isothermal crystallization kinetics with constant heating or cooling rates, an apparent m -order reaction model is approximately equivalent to the nucleation and growth model of Avrami in the vicinity of the inflection points of the corresponding crystallization curves. Since the apparent m -order reaction model is defined for every real, positive apparent reaction-order m , a distinct Avrami index n , which is valid for the characterization of isothermal and non-isothermal crystallization experiments with constant heating or cooling rates, can always be related to any apparent reaction-order m . Therefore, two types of Avrami master curves, which are dependent merely on the Avrami index n and which describe the isothermal polymer crystallization thoroughly, can be obtained by performing non-isothermal experiments with constant heating or cooling rates.     

纳米粒子改性PET的非等温结晶动力学

研究了有机纳米丁苯吡粉末橡胶、无机纳米粒子添加到聚对苯二甲酸乙二酯(PET)后对PET结晶行为的影响.并探讨了不同降温速率下3种体系降温过程中的结晶行为及基于Jeziomy理论和莫氏理论的结晶动力学.研究表明,3种纳米粒子对PET结晶动力学的影响是不同的,纳米粉末橡胶在较低结晶度时符合Jeziorny理论,而无机纳米粒子则对莫氏理论有较好的相关性.由莫氏理论计算出的参数表明,达到同样结晶度时有机化黏土促进PET结晶的效果比纳米CaCO3好.     

含较高立构缺陷聚乳酸的非等温结晶动力学

用非等温结晶动力学研究了聚乳酸(PLA)的结晶行为,利用Hoffman-Weeks外推法以及Baur等提出的方程反推出PLA中的右旋组分摩尔分数为7.2%.较高的右旋组分摩尔分数是PLA结晶过程中成核速率低的主要因素.添加质量分数为2%滑石粉等成核剂后,PLA结晶速率没有明显提高;含10%滑石粉的PLA结晶速率略上升,...     

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.     

Non-isothermal crystallization kinetics of polypropylene/MAP-POSS nanocomposites

Non-isothermal crystallization kinetics of polypropylene (PP)/methylacryloypropy polyhedral oligomeric silsesquioxanes (MAP-POSS) nanocomposites (PP/MAP-POSS) were investigated by DSC at various cooling rates. Jeziorny and Mo method were used to study the non-isothermal crystallization kinetics. The results show that the Jeziorny and Mo method are all successful in describing the non-isothermal crystallization kinetics of PP/MAP-POSS nanocomposites. The MAP-POSS can act a role of heterogeneous nucleation and increase the crystallization rate constant Z _c and decrease crystallization half time t _1/2, and the spherulite crystal size decreases, the inter-spherulitic action or crosslinking structure each other appear at the appropriate content. The DSC peak temperature T _p increase about 5 °C, t _1/2 reduce 0.21 min at 6 % content of MAP-POSS and heating rate of 10 °C/min. The MAP-POSS can also increase the mechanical property of PP/MAP-POSS nanocomposites, the tensile strength and impact strength increase from 12.97 to 19.93 MPa and from 33.2 to 52.6 kJ/m², respectively, at 4 % content of MAP-POSS. But the spherulitic crystal becomes larger and boundaries become clearer again; the macrophase separation will occur and mechanical properties decrease when more and more MAP-POSS was added. The nanocomposite has the best mechanical property at 4 % content of MAP-POSS.     

CHDM改性PBT共聚酯的非等温结晶动力学研究

采用直接酯化熔融缩聚工艺路线,以1,4-环己烷二甲醇(CHDM)为第三单体,制备了CHDM改性聚对苯二甲酸丁二醇酯(PBT)共聚酯(PBTG),利用差示扫描量热仪测定了PBT及PBTG在不同降温速率下的降温曲线,并采用Jeziorny方法分析了PBTG的非等温结晶动力学。结果表明:随着降温速率的增加,PBT及PBTG的结晶温度降低,结晶曲线变宽;在相同降温速率下,相比PBT,加入第三单体CHDM后的PBTG的非等温结晶动力学速率常数降低,证明PBTG的非等温结晶能力降低,结晶速率变慢; CHDM的加入不利于PBT结晶。     

Non-isothermal crystallization kinetics of calcium carbonate-filled β-crystalline phase polypropylene composites

The non-isothermal crystallization behaviour of high purity β-phase and α-phase polypropylene (PP) and their calcium carbonate-filled composites was investigated by means of differential scanning calorimetry. High purity β-PP polymer was prepared by adding an effective β-nucleator consisting of equal amounts of pimelic acid and calcium stearate. The crystallization temperature and crystallization rate coefficient of pure β-PP polymer were considerably higher than those of the α-PP polymer. This was due to the β-PP polymer containing nucleating agents, which act as nuclei for β-spherulites. The calcium carbonate content had little or no effect on the crystallization rate coefficient and Ozawa exponent of the β-phase PP in the composites. On the other hand, the crystallization temperature, crystallization rate coefficient and Ozawa exponent of the α-phase PP composites depended on the calcium carbonate loading. The effect of calcium carbonate additions on the crystallization of α-PP and β-PP is discussed. ©1997 SCI     

TLCPa/PA 66的非等温结晶动力学

研究了新型热致液晶聚酰胺(TLCPa)与聚酰胺(PA)66熔融共混物的非等温结晶行为。w(TLCPa)为0～30％的共混物的结晶温度和结晶度分别从PA 66的235．83℃和39．8％逐步下降为224．70℃和30．8％．PA 66的结晶明显受到抑制。w(TLCPa)为10％的共混物的Ozawa指数从PA 66的3～4降为2左右,共混物有着不同于纯PA 66的成核和晶体生长机理。TLCPa与PA 66具有较好的相容性。     

小本体聚丙烯及其接枝丙烯酰胺的非等温结晶动力学

采用DSC方法测试了小本体聚丙烯（PP）及其接枝丙烯酰胺（PP-g-AM）非等温结晶过程的释热情况,并对两组实验数据分别运用Jeziorny法和Mo法进行了处理和比较.结果表明,两种方法均可准确地描述PP及PP-g-AM的非等温结晶过程.PP接枝前后Avrami指数n无明显改变,表明两者结晶机理基本相同;由Jeziorny法得到接枝产物的校正晶体增长速率常数Z_c略大于纯PP的Z_c;由Mo法计算得出,PP-g-AM的F(T)值略小于纯PP的F（T）,表明接枝物的相对结晶速率略大于纯PP的相对结晶速率.     

PP/多壁碳纳米管复合材料的非等温结晶动力学

用超声处理溶液絮凝法制备聚丙烯(PP),多壁碳纳米管(MWNT)复合材料。扫描电子显微镜分析表明, MWNT呈纳米级分散。用Jeziomy法和MO法对材料非等温结晶差示扫描量热法结果进行动力学处理,发现复合材料的结晶峰温升高,半结晶时间减小;但随MWNT含量变化不大。复合材料的结晶速率常数比纯PP大;Avrami指数比纯PP小。要达到相同的结晶度,复合材料所需的降温速率小于纯PP。MWNT可成为PP的成核剂。     

降解PP/EPDM共混物的非等温结晶动力学

使用过氧化二异丙苯降解聚丙烯(PP),熔融法制备降解PP与三元乙丙橡胶(EPDM)共混物,采用广角X射线衍射及差示扫描量热法分析了降解PP/EPDM共混物的晶体结构及非等温结晶动力学。结果发现:PP降解后β晶的(300)晶面消失,导致降解PP及其共混物韧性下降、晶粒的粒径分布变宽;降解PP/EPDM共混物在非等温结晶过程中有明显的快速初级结晶和缓慢的次级结晶过程,降解PP以均相成核的三维球晶方式生长,Avrami指数与Ozawa指数相等,Jeziorny方程和Ozawa方程都可以很好地描述降解PP/EPDM共混物的非等温结晶过程。     

纳米Al_2O_3改性聚丙烯的非等温结晶动力学

采用差示扫描量热法研究了聚丙烯(PP)及PP/纳米Al_2O_3复合材料的非等温结晶动力学。结果表明:纳米Al_2O_3有异相成核的作用,使PP的结晶峰温升高;PP的半结晶时间随纳米Al_2O_3含量增大而减小;纳米粒子的填充使PP的结晶活化能(△E)增大,含纳米Al_2O_3质量分数为2%的PP的△E最大。     

不同相对黏度PA6的非等温结晶动力学研究

以相对黏度(ηr)为2.0,2.4,2.8,3.4,4.0的5种聚酰胺6(PA6)切片为研究对象,采用差示扫描量热法测试其在不同冷却速率(?)下的非等温结晶过程;基于Jeziorny法和Mo法对不同 ηr的PA6的非等温结晶动力学进行对比分析,并采用Kissinger法计算其结晶活化能(△E).结果表明:PA6的 ηr...     

Non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends☆

The non-isothermal crystal ization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry (DSC). The Mo equation was employed to analyze the non-isothermal crystallization data. The crystallization activation energies were also evaluated by the Kissinger method. The results show that the crystallization onset temperature (Tonset) and crystallization peak temperature (Tp) decrease with the increase of the content of reactive microgel, whileΔT (Tonset–Tp), the crystallization half-time (t1/2) and the crystal ization enthalpy (ΔHc) increase. The required cooling rates of blends are higher than that of neat nylon 6 in order to achieve the same relative crystallinity in a unit of time. The crystallization activation energies of the reactive microgel/nylon 6 blends are greater than those of the neat nylon 6. When the content of reactive microgel is 30%, the relative crystallinity (Xt) reaches the maximum.     

加入不同种类成核剂抗冲击共聚PP的非等温结晶动力学

采用差示扫描量热仪研究了加入羧酸盐类成核剂和有机磷酸盐类成核剂的抗冲击共聚聚丙烯2500H的熔融、结晶和非等温结晶行为。结果表明:加入质量分数为0.02%的成核剂后,2500H的结晶度和所有结晶特征温度均提高,其中,结晶度提高0.3%~3.0%,结晶温度提高4.4~11.0℃,结晶起始温度提高4.4~12.2℃,结晶终止温度提高6.3~11.6℃。与加入有机磷酸盐类成核剂的2500H相比,加入羧酸盐类成核剂的2500H具有更低的结晶过冷度,成核能力相对较高;但加入有机磷酸盐类成核剂的2500H表现出更快的结晶速率,而加入羧酸盐类成核剂的2500H虽然在高温条件下能促使2500H较快形成晶核,但并不利于结晶速率的提高。     

Non-isothermal crystallization kinetics of poly(ethylene terephthalate)/mica composites

The non-isothermal crystallization kinetics of pure poly(ethylene terephthalate) (PET), PET/mica and PET/TiO₂-coated mica composites were investigated by differential scanning calorimetry with different theoretical models, including the modified Avrami method, Ozawa method and Mo method. The activation energies of non-isothermal crystallization were calculated by Kissinger method and Flynn–Wall–Ozawa method. The results show that the modified Avrami equation and Ozawa theory fail to describe the non-isothermal crystallization behavior of all composites, while the Mo model fits the experiment data fair well. It is also found that the mica and TiO₂-coated mica could act as heterogeneous nucleating agent and accelerate the crystallization rates of PET, and the effect of TiO₂-coated mica is stronger than that of mica. The result is further reinforced by calculating the effective activation energy of the non-isothermal crystallization process for all composites using the Kissinger method and the Flynn–Wall–Ozawa method.