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。     

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.     

支化PET的非等温结晶性能研究

采用直接酯化缩聚法,以3-羟甲基丙烷(TMP)或季戊四醇(PER)为支化剂,制备支化PET;探讨了支化剂对其结晶性能的影响;利用差示扫描量热(DSC)法研究了支化PET的非等温结晶性能。结果表明:支化剂TMP或PER的加入可以有效增强PET的结晶能力,但过量的支化剂会抑制PET的结晶;支化PET的非等温结晶Avrami指数为3.03~4.42,其结晶机理为均相成核和异相成核相结合;支化PET的结晶活化能比常规PET的低,支化PET结晶对温度的依赖性降低。     

增韧改性聚对苯二甲酸丁二酯/聚碳酸酯共混物非等温结晶动力学与力学性能

The polybutylene terephthalate (PBT）/ polycarbonate (PC）blends modified by toughening agent（S-2001）consisting of methyl methacrylate, styrene and silicone were prepared via melt blending.The non-isothermal crystallization kinetics of the blends were investigated by scanning calorimetry (DSC）at different cooling rate of 5℃·min^-1,10℃·min^-1,15℃·min^-1, and the data were analyzed by using modified Avrami theories of the Jeziorny method.The influence of toughening agent相似文献   

回收PET共混物的非等温结晶和熔融行为

采用双螺杆挤出机制备了聚丙烯(PP)/回收聚对苯二甲酸乙二酯(r-PET)、r-PET/马来酸酐接枝PP(PP-g-MAH)和r-PET/甲基丙烯酸缩水甘油酯接枝PP(PP-g-GMA)共混物,并研究了共混物组成、熔融温度与时间以及降温速率对共混物非等温结晶与熔融行为的影响.结果表明,r-PET与PP共混,结晶温度均提高,这与组分间起到异相成核诱导结晶作用有关.r-PET结晶温度随PP-g-MAH用量增加而降低,但受PP-g-GMA用量影响较小;r-PET可提高PP-g-MAH结晶温度,但降低PP-g-GMA结晶温度.熔融温度提高,共混物中PP结晶温度和熔点均降低,r-PET熔融峰形和熔点取决于共混物的熔融温度及界面相互作用.     

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。     

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。     

Polyoxymethylene/thermoplastic polyurethane blends compatibilized with multifunctional chain extender

Novel compatibilized polyoxymethylene/thermoplastic polyurethane (POM/TPU) blends are successfully developed using multifunctional chain extender, Joncryl ADR‐4368, as the compatibilizer. The outstanding compatibilization efficiency of Joncryl on POM/TPU blend was demonstrated by its even higher mechanical properties with only 0.5 wt % of Joncryl than those with 5 wt % of three commonly used compatibilizers. Addition of only 0.5 wt % Joncryl can double the impact strength and significantly improve its tensile strength and flexural strength for POM/TPU (75/25) blend. SEM images show that Joncryl can reduce TPU particle size and enhance the interfacial interactions between POM and TPU. The interparticle distance of TPU in POM/TPU/Joncryl blends was calculated as 0.2 μm, quite close to the critical matrix ligament thickness of POM/TPU blends (0.18 μm). The impact force profile vividly shows that the addition of Joncyl in POM/TPU blends can dramatically increase the total impact energy absorbed by this blend system and enhance the interfacial interactions between POM and TPU. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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...     

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.     

Effect of mechanical recycling on crystallization,mechanical, and rheological properties of recycled high-density polyethylene and reinforcement based on virgin high-density polyethylene

This study investigated the effects of mechanical recycling on the crystallization, mechanical, thermal, and rheological properties of recycled high-density polyethylene (rHDPE), as well as vHDPE/rHDPE pellets and films made by different compositions. The results confirmed the presence of contaminants in rHDPEs, and the crystalline diameter of rHDPE is smaller than that of virgin high-density polyethylene (vHDPE), with diameters ranging from 0.60 to 0.72 μm. The content of 75 wt% vHDPE in rHDPE film could repair the defects of crystalline morphology to approximate that of vHDPE films and significantly improve the elongation at break. The temperature required for the transition from crystalline to amorphous state of rHDPE film was 2°C lower than that of vHDPE, and the crystallization time and crystallinity declined compared to that of vHDPE. For rheological performance, the apparent shear viscosity and melt fluidity of rHDPE were worse than those of vHDPE. The blending of low rHDPE with vHDPE is a feasible option not only to reduce plastic waste but also to maintain acceptable properties of the blend composition.     

Thermal and crystallization properties of PBT/ABAS blends

Blends of poly(butylene terephthalate) (PBT) with poly(acrylonitrile‐butyl acrylate‐styrene) (ABAS) were characterized by differential scanning calorimetry, infrared, thermogravimetric analysis, and wide‐angle X‐ray diffraction (WAXD) studies. Addition of ABAS polymer to PBT improved the thermal stability of PBT. Infrared studies showed that ABAS polymer chemically interacts with PBT. The crystallization behavior of PBT was modified in the presence of ABAS polymer. The ABAS polymer showed inappreciable effect on melting behavior of PBT but decreased its crystallization. WAXD studies showed some modification in PBT peaks and a peak with increasing intensity corresponding to the β‐crystalline form of PBT. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties of recycled PVC blends with styrenic polymers

The aim of this study is to improve the performance of blends made from recycled polyvinyl chloride (PVC), coming from credit card waste, so that these blends can be used for those applications that must fulfil some requirements with regard to mechanical properties and stability with temperature alterations. With this aim in mind, two polymers of styrenic origin have been combined: styrene acrylonitrile (SAN) and acrylonitrile butadiene styrene (ABS). These polymers are characterized by a satisfactory balance of mechanical properties and thermal stability. PVC blends with both virgin and recycled styrenic polymers have been studied throughout the entire range of compositions. The prior degradation of the recycled materials has been studied by means of Fourier transformed infrared spectroscopy (FTIR).The behavior of the observed T_g values has been analyzed using differential scanning calorimetry (DSC), and the existence of partial miscibility between the different components has been studied. The mechanical properties have been determined using tensile and Charpy impact tests. The thermal stability of the PVC blends with temperature changes has been determined using the Vicat softening temperature (VST). Finally, the fracture surface of the various blends has been analyzed using scanning electron microscopy (SEM). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2464–2471, 2006     

Melting,crystallization behaviors,and nonisothermal crystallization kinetics of PET/PTT/PBT ternary blends

The melting, crystallization behaviors, and nonisothermal crystallization kinetics of the ternary blends composed of poly(ethylene terephthalate), poly(trimethylene terephthalate) (PTT) and poly(buthylene terephthalate) (PBT) were studied with differential scanning calorimeter (DSC). PBT content in all ternary blends was settled invariably to be one‐third, which improved the melt‐crystallization temperature of the ternary blends. All of the blend compositions in amorphous state were miscible as evidenced by a single, composition‐dependent glass transition temperature (T_g) observed in DSC curves. DSC melting thermograms of different blends showed different multiple melting and crystallization peaks because of their various polymer contents. During melt‐crystallization process, three components in blends crystallized simultaneously to form mixed crystals or separated crystals depending upon their content ratio. The Avrami equation modified by Jeziorny and the Ozawa theory were employed to describe the nonisothermal crystallization process of two selected ternary blends. The results spoke that the Avrami equation was successful in describing the nonisothermal crystallization process of the ternary blends. The values of the t_1/2 and the parameters Z_c showed that the crystallization rate of the ternary blends with more poly(ethylene terephthalate) content was faster than that with the lesser one at a given cooling rate. The crystal morphology of the five ternary blends investigated by polarized optical microscopy (POM) showed different size and distortional Maltese crosses or light spots when the PTT or poly(ethylene terephthalate) component varied, suggesting that the more the PTT content, the larger crystallites formed in ternary blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

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。     

氯化聚乙烯橡胶改性聚丙烯的非等温结晶行为研究

用示差扫描量热仪(DSC)对氯化聚乙烯橡胶(CM)改性聚丙烯(PP)的非等温结晶行为进行了研究。结果表明,随着降温速度上升,样品结晶温度下降,结晶速度上升。在以15k/min与20k/min速度降温时,发现两者的结晶行为相一致。采用TCHC交联剂的1#样品的结晶温度与速度都大于采用DCP交联剂的2#样品,前者的硫化效率低,对结晶影响小。本文又通过求解非等温结晶动力学参数与结晶活化能,进一步解释了1#与2#样品的结晶行为。     

Non-isothermal crystallization of Ziegler Natta i-PP-graphene nanocomposite: DSC and new model prediction

Crystallization occurs in processing i-PP-GnP nanocomposites, and these nanocomposites have the potential to replace traditional fillers and be used to fabricate advanced materials and technology. Therefore, this subject was comprehensively investigated by applying a recent crystallization model, non-isothermal DSC experiments, Raman spectroscopy, and WAXRD. The multi-layer GnP-induced nucleation and the crystal growth rates were modelled. The overall modelling effort generated new insights, results, and explanations. This study confirmed and elucidated, or refuted several published conclusions. It has also been reported that the present model can pursue differences in catalyst-mediated i-PP backbone defects (stereo and regio) by simulating the relative crystallization profile and determining the crystallization kinetic triplet (n, k _o, and E _a). The multiple roles played by GnP were underscored, which exceed what the related literature currently reports. The Raman and XRD work revealed the interaction between GnP and i-PP. The shear-induced dispersion of GnP that occurs during extrusion significantly affected i-PP crystal size distribution. The present approach can also assess the effects of catalyst type and structure, and backbone defect types and their distribution on the non-isothermal crystallization of, in general, polyolefin blends and nanocomposites.     

聚丁二酸丁二醇酯/聚乙二醇硬脂酸酯共混物非等温结晶行为

以聚丁二酸丁二醇酯（PBS）和聚乙二醇硬脂酸酯（PEOST）为原料,采用溶液共混法制备了PEOST质量分数分别为10%（POS-10）和30%（POS-30）的两种合金材料。通过差示扫描量热法（DSC）研究了合金材料的非等温结晶行为,用莫志深（Mo）法分析了PBS的非等温结晶动力学,采用Kissinger法和Friedman法计算PBS的结晶活化能,并用红外（FTIR）和偏光显微镜（POM）进行表征。研究结果表明：PBS先结晶形成结晶微区不利于PEOST结晶,而较高含量的PEOST有利于PBS的结晶。受PBS先结晶的影响,POS-10降温DSC曲线没有出现PEOST的结晶峰,而POS-30在低的降温速率情况下出现了PEOST双结晶峰;升温DSC曲线中两试样均出现了PEOST的熔融峰。在相同的冷却速率下,POS-30的PEOST熔融温度（T_m）和熔融焓（△H_m）大于POS-10;POS-30的PBS结晶峰温度（T_p）、结晶焓（△H_c）大于POS-10,而结晶半峰宽（D）值更小;但两者的T_m和△H_m相当。随冷却速率的增加,PBS的D值增大,而PEOST的D值却降低;冷却速率的增加对PBS的T_m值影响不大,但使PEOST的T_m略有减小。Mo法适合用于共混物中PBS的非等温结晶动力学分析。POS-30的PBS绝对值结晶活化能要大于POS-10。POS-30在红外光谱谱图中出现了PEOST结晶的红外响应峰（1109cm^-1和841cm^-1）而POS-10没有。     

Influence of compatibilizers on mechanical properties,crystallization, and morphology of polypropylene/scrap rubber dust blends

Polypropylene blends containing a dispersed phase of scrap rubber dusts obtained from sport shoes manufacture; midsole (M, vulcanized EVA foam) and outsole (O, vulcanized rubber blend of NR, SBR, and BR) were studied. The influence of various compatibilizers on the mechanical properties of these blends were investigated. Significant development of impact strength was attained by using 6 and 10 phr of styrene–ethylene–butylene–styrene (SEBS) and maleic anhydride‐grafted styrene–ethylene–butylene–styrene (SEBS‐g‐MA) as compatibilizers for both compounds filled with midsole and outsole dusts. The tensile strength of each compound was slightly decreased when the compatibilizer loading increased, whereas the elongation at break was significantly increased. The enhancements of the impact strength and the elongation at break are believed to arise from reduction of interfacial tension between two phases of the rubber and the PP, which results in some reduction of the particle size of the fillers. Scanning electron microscopy (SEM) confirmed the evidence of the reduction of scrap rubber dust into small rubber particle sizes in the compound, and also showed the occurrence of some fibrils. Optical microscopy (crossed polars) observations suggested that the addition of the rubber dust resulted in a less regular spherulite texture and less sharp spherulite boundaries. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 148–159, 2002