β成核剂TMB-5对iPP注塑件结晶结构和性能影响的研究

TMB-5是一种有机酰胺类β成核剂。通过偏光显微镜、差示扫描量热仪、广角X射线衍射仪和万能拉伸机等手段研究了不同含量TMB-5对等规聚丙烯(i PP)注塑制件沿厚度方向的结晶形态结构及制品的力学性能的影响。结果表明,TMB-5质量分数为0.1%时,冲击强度提高幅度较大,进一步提高成核剂含量,冲击强度逐渐降低;与之相对应的是,拉伸强度呈现先降低后增加的趋势。β成核剂对i PP的晶体形态和结构影响较大,且注塑制件自皮层到芯层的晶体结构存在一定差异。     

成核剂对聚乳酸挤出流延膜结晶性能的影响

聚乳酸作为一种优异的可降解塑料近年来发展迅速,受PLA结晶性速度慢,脆性高的影响,改善PLA结晶性能的研究日益受到关注。本文研究了两种成核剂对挤出流延PLA结晶性能的影响。实验结果显示,挤出流延的PLA薄膜的结晶度仍然很低,在升温过程有明显的冷结晶行为,成核剂对PLA结晶的贡献远低于冷却速度的影响。相较于TMC300,使用滑石粉(Talc)作为成核剂,能更快提升PLA的结晶速率,提升结晶完善性。挤出流延的PLA膜还需要经过退火处理使结晶完善,释放加工过程的取向内应力。使用两种成核剂的样品大约经过20分钟的热处理即可完成结晶,在退火过程,Talc显示出更为优越的结晶加速行为。因此相较而言,Talc更适合在PLA挤出流延制膜中应用。     

自组装成核剂TMB-5对HDPE晶体结构与结晶行为的影响

将自组装成核剂TMB-5应用于高密度聚乙烯(HDPE)的晶体结构调控,以提高HDPE制品的力学性能。通过偏光显微镜(POM)、XRD和DSC分析,研究了TMB-5在HDPE基体中的自组装行为,及其对HDPE结晶行为和晶体结构的影响。结果表明:TMB-5可在HDPE中发生自组装,且自组装行为与TMB-5的溶解度相关。在180、230和250℃三个最高加热温度下,TMB-5可分别自组装形成颗粒状、纤维状和三维树枝状结构,进而诱导HDPE以TMB-5为模板,生长成与模板相同的晶体形态。此外,加入TMB-5可使HDPE的结晶温度和结晶起始温度升高1~2℃,并使其晶粒细化、晶粒尺寸分布变宽,结晶度由66%提高至79%。     

成核剂对聚乳酸结晶行为及热性能的影响

采用熔融共混法制备了聚乳酸/成核剂复合材料,通过结晶速率测试仪、偏光显微镜(POM)、差示扫描量热仪(DSC)、X射线衍射仪(XRD)和负荷热变形温度测定仪对材料的结晶行为及热行为进行了研究。结果表明:与滑石粉相比,多酰胺类化合物(TMC)在聚乳酸基体中的成核效果更为明显,TMC的加入未改变聚乳酸的晶型,但显著提高了聚乳酸的结晶速率和结晶度;当所有样品在120℃下退火2 min时,与纯聚乳酸及滑石粉成核的聚乳酸相比,TMC成核的聚乳酸耐热温度最高,可达105.6℃。     

成核剂TMC-210对聚乳酸结晶的影响

通过采用红外(IR)、X光衍射(XRD)和差示扫描量热仪(DSC)等手段考察了成核剂TMC-210对聚乳酸(PLA)结晶性能的影响,试验结果表明TMC-210可以在不改变PLA结构的情况下使PLA的半结晶时间随添加量增加而减小。     

成核剂TMC-200对聚乳酸结晶的影响

采用红外光谱分析、X光衍射分析(XRD)和差示扫描量热分析(DSC)等手段考察了成核剂TMC-200对聚乳酸结晶性能的影响。结果表明,TMC-200是一种高效成核剂,可以在不改变聚乳酸结构的情况下有效提高聚乳酸的结晶速度。     

成核剂对聚乳酸结晶及力学性能的影响

采用熔融共混法,用成核剂对聚乳酸(PLA)进行成核改性.通过差示扫描量热仪(DSC)、X射线衍射仪(XRD)、偏光显微镜(PLM)及力学性能和热变形温度(HDT)等测试,研究成核剂对PLA的结晶、力学和耐热性能的影响.结果表明:改性PLA的结晶温度和结晶度提高,晶体尺寸减小,且PLA的晶型结构没有改变;改性PLA的拉伸强度、拉伸屈服强度和刚性降低,韧性有所提高;将注射成型的改性PLA样条进行退火处理后,耐热性有很大提高.     

成核剂TMC-300对聚乳酸结晶的影响

针对聚乳酸结晶速度慢、结晶度低的问题,通过添加聚乳酸成核剂TMC-300来改善其结晶性能。实验过程采用热重、红外、结晶速率测定仪以及X光衍射等手段考察了成核剂TMC-300对聚乳酸结晶的影响。成核剂TMC-300没有对聚乳酸的结构和晶型造成影响,但大大缩短了半晶时间。在0.8%的添加量下,半晶时间低至40 s。结果表明,TMC-300是一种有效的聚乳酸成核剂。     

聚乳酸结晶成核剂的研究进展

聚乳酸作为一种新型可生物降解高分子材料,具有优良的机械性能和生物降解性,但结晶速度缓慢也制约了其应用,添加结晶成核剂是一种改善聚合物结晶行为的有效手段,本文综述近年国内外对聚乳酸结晶成核剂的研究情况。     

聚乳酸结晶成核剂的研究进展

聚乳酸(PLA)是一种生物基可降解聚酯,在过去的十年里迅速成为一种极具竞争力的商业材料。虽然聚乳酸拥有高模量,高强度和高透明性等优点,但目前制约其应用的一个瓶颈就是对其结晶的控制。在PLA的发展过程中,成核剂在其结晶领域一直扮演着一个重要的角色。本文通过大量文献总结和比较阐述了目前聚乳酸成核剂领域的最新进展。     

一种成核剂对聚乳酸结晶行为的影响

通过示差扫描量热法研究了一种新型成核剂对聚乳酸结晶行为的影响,并通过Avrami方程对其结晶动力学进行分析。结果显示,当聚乳酸中加入0.3%质量分数的成核剂,即可使其半结晶时间由61.4 min缩短至9.2 min。通过偏光显微镜对聚乳酸及含成核剂的聚乳酸的晶体形貌观察,发现成核剂可以显著的提高聚乳酸的结晶速率,相同时间内,球晶数量显著增多,晶粒尺寸明显减小。     

Effects of an organic phosphorus nucleating agent on crystallization behaviors and mechanical properties of poly(propylene)

The effects of an organic phosphorus nucleating agent on the crystallization behavior and mechanical properties of poly(propylene) were investigated. As the concentration of nucleating agent increased from 0 to 0.8%, the tensile and flexural strengths of the nucleated poly(propylene) resin increased by 15%, the flexural modulus increased by 35%, the crystallization peak temperature increased by 10°C, and the nucleation density (calculated with the nonlinear Voltrra integral equation) increased by 10⁶ times. Mechanical properties increased with nucleation density. Linear equations between the mechanical properties and the logarithmic nucleation density were revealed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 297–301, 2003     

Effect of biobased and biodegradable nucleating agent on the isothermal crystallization of poly(lactic acid)

The effect of chemically modified thermoplastic starch (CMPS) on the thermal properties and isothermal crystallization kinetics of poly(lactic acid) (PLA) was studied by differential scanning calorimetry (DSC) and compared to that of granular starch and an inorganic nucleating agent, talc. Nucleated PLA showed an additional crystallization of PLA, which affected the melting temperature. The crystallinity and crystallization rate of PLA were considerably enhanced by addition of CMPS, even at 0.1% content, and the amount of the CMPS had little effect on the thermal properties and isothermal crystallization kinetics of PLA. The effect of CMPS as a nucleating agent was comparable to that of granular starch but slightly less than that of talc. However, CMPS can offer a fully biodegradable nucleating agent with no residues remaining for the biobased and biodegradable polymers.     

Nonisothermal crystallization kinetics of poly(lactide)—effect of plasticizers and nucleating agent

Poly(lactide), a bio‐based aliphatic polyester, is a subject to large research effort. One point of optimization is the acceleration of its crystallization kinetics to promote crystallinity under nonisothermal polymer processing conditions by means of compounding with nucleating agents and plasticizers. The nonisothermal crystallization kinetics of neat and formulated poly(L,D ‐lactide) (PDLLA) from the melt with talc and polyethylene glycol (PEG) or acetyl tributyl citrate (ATBC) were studied with the help of the Avrami–Jeziorny and Liu–Mo analysis. Talc showed to be a moderately efficient nucleating agent, as it causes only small increase of crystallization kinetics and shows no effect on the crystallization activation energy. A synergistic effect with plasticizers was observed, expanding the crystallization window significantly. PEG was found to be a more efficient plasticizer than ATBC but causes large decrease in the molecular weight average of PDLLA upon thermal treatment. The talc/ATBC system is efficient starting with an ATBC concentration of 9 wt%. The acceleration observed was a crystallization half‐time decrease of 30% compared to neat PLA and reaching maximum crystallization enthalpies even at cooling rate of 25°C min^?1. The ATBC/talc system can be recommended as an efficient system for acceleration of nonisothermal crystallization kinetics of PDLLA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effect of lignin particles as a nucleating agent on crystallization of poly(3‐hydroxybutyrate)

The effect of lignin fine powder, as a new kind of nucleating agent, on the crystallization process of poly(3‐hydroxybutyrate) (PHB) was studied. The kinetics of both isothermal and nonisothermal crystallization processes from the melt for both pure PHB and PHB/lignin blend was studied by means of differential scanning calorimetry. Lignin shortened the crystallization half‐time t_1/2 for isothermal crystallization. The activation energy ΔE for PHB/lignin and pure PHB in the isothermal crystallization process was ?237.40 and ?131.22 kJ/mol, respectively, clearly indicating that the crystallization of the PHB/lignin blend was more favorable than that of pure PHB from a thermodynamic perspective. At the same time, according to polarized optical microscopy, the rate of spherulitic growth from the melt increased with the addition of lignin, which is ascribed to the reduction of surface fold energy σ_e, that is, σ_e is 59.2 × 10^?3 and 41.6 × 10^?3 J m^?2 for pure PHB and PHB/lignin, respectively. Polarized optical microscopy also showed that the spherulites found in PHB with lignin were smaller in size and greater in number than those found in pure PHB. The wide‐angle X‐ray diffraction indicated that an addition of lignin caused no change in the crystal structure and degree of crystallinity. These results indicated that lignin is a good nucleating agent for the crystallization of PHB. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2466–2474, 2004     

Effect of sepiolite on the crystallization behavior of biodegradable poly(lactic acid) as an efficient nucleating agent

To enhance the crystallization kinetics of poly(lactic acid) (PLA), fibrous sepiolite was explored for nucleating the crystallization of PLA. PLA/sepiolite nanocomposites were prepared via the melt‐extrusion method. The effect of sepiolite on the crystallization behavior, spherulite growth and crystal structure of PLA were investigated by means of differential scanning calorimetry (DSC), polarized optical microscope (POM), wide angle X‐ray diffraction (WAXD), Fourier transform infrared (FTIR), and scanning election microscope (SEM). On the basis of DSC and POM results, the overall crystallization kinetics of PLA/sepiolite nanocomposites were significantly enhanced leading to higher crystallinity and nucleation density, faster spherulite growth rate (G) and lower crystallization half‐time (t_1/2) compared with the neat PLA. Under non‐isothermal conditions, the PLA blend comprising 1.0 wt% of sepiolite still revealed two crystallization peaks upon cooling at a rate of 35°C/min. Above phenomena strongly suggested that sepiolite was an effective nucleating agent for PLA. FTIR and WAXD analyses confirmed that the crystal structure of PLA matrix was the most common α‐form. SEM micrographics illustrated the fine three‐dimensional spherulite structures with the lath‐shape lamellae regularly arranged in radial directions. POLYM. ENG. SCI., 55:1104–1112, 2015. © 2014 Society of Plastics Engineers     

成核剂对聚丙烯力学性能与结晶行为的影响

研究了两种类型的成核剂对国产共聚聚丙烯的结晶形态以及拉伸强度、冲击强度的影响。结果表明:加入TMB-5型成核剂,聚丙烯的冲击强度有一定程度改善,w(TMB-5)为0.1%时,改性聚丙烯的缺口冲击强度达到最大;TMX-2型成核剂可改善聚丙烯的拉伸性能,但抗冲击性能降低较大;TMB-5型成核剂可显著地改变聚丙烯的结晶行为,诱导聚丙烯在结晶过程中主要形成β晶;TMX-2型成核剂可诱导聚丙烯在结晶过程中主要生成α晶,与纯PP相比,α晶的形成能力增强。     

Rapid crystallization of poly(l-lactic acid) induced by a nanoscaled zinc citrate complex as nucleating agent

A nanoscaled zinc citrate complex (ZnCC) was synthesized by the reaction of zinc acetate and citric acid using solution method. As a new eco-friendly nucleating agent, ZnCC was introduced into poly(l-lactic acid) (PLLA) via melt blending. The nonisothermal and isothermal crystallization, melting behavior, crystalline morphology and mechanical properties of the PLLA/ZnCC blends were investigated. It is found that ZnCC exhibits much more prominent nucleation activity on the crystallization of PLLA than conventional nucleating agent talc and commercial zinc citrate (ZnCit). By loading 0.05 wt% ZnCC, PLLA can complete crystallization upon cooling at 10 °C/min, and the crystallization peak shifts to a higher temperature with increasing ZnCC content. In the case of isothermal crystallization from the melt, the addition of ZnCC leads to a shorter crystallization time and a faster overall crystallization rate. Besides, the nucleation density of PLLA increases and the spherulite size decreases significantly in the presence of ZnCC. Epitaxy is the possible mechanism to elucidate the nucleation phenomenon of PLLA/ZnCC system. The tensile results show that ZnCC has a plasticization effect on the amorphous PLLA. Through a short-time annealing procedure, the mechanical properties such as tensile modulus and storage modulus of PLLA are improved by the addition of ZnCC.     

Effect of boron nitride as a nucleating agent on the crystallization of bacterial poly(3‐hydroxybutyrate)

Different concentrations of boron nitride (BN) (0.2–0.8 wt %) are added to poly (3‐hydroxybutyrate) (PHB) as a nucleating agent. Polarized Optical Microscopy (POM) coupled to Differential Scanning Calorimetry (DSC) allow to monitor the isothermal and nonisothermal crystallization of neat and nucleated PHBs. It is found that the addition of BN to PHB modifies the mechanisms of crystallization without changing the crystallinity degree. DSC can replace POM whenever POM does not allow to estimate the spherulites growth rate. The Hoffman‐Lauritzen theory is used to explain the role of BN. The nucleating agent allows polymer crystallization at lower supercooling degrees. The regime II of crystallization is observed for nucleated PHBs. A modification of the coupling effect between the amorphous and the crystalline phases is evidenced. It is shown that a concentration of 0.2 wt % BN is sufficient to decrease the glass transition temperature and modify the crystallization mechanisms of PHB. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effective nucleating chemical agents for the crystallization of poly(trimethylene terephthalate)

This study focused on the crystallization promotion of poly(trimethylene terephthalate) (PTT), with an aim at engineering thermoplastics applications. The effects of organic sodium (Na) salts, including Na stearate, Na benzoate, disodium‐p‐phenolsulfonate (2Na‐p‐PS), disodium‐p‐hydroxybenzoate (2Na‐p‐HB), and the sodium ionomer of poly(ethylene‐co‐methacrylic acid) (Na‐EMAA), were investigated as nucleating chemical agents with differential scanning calorimetry and capillary viscometry. For comparison, the effect of fine talc powder was also examined. The chemical agents were generally more effective than fine talc powder. Na stearate and Na benzoate caused large‐scale decomposition of PTT. 2Na‐p‐PS was quite thermally stable and caused little decomposition. 2Na‐p‐HB was the most efficacious of the nucleating chemical agents and caused mild decomposition. Na‐EMAA was the most thermally stable and induced an increase in melt viscosity. A remarkable improvement in the crystallization rate of PTT was successfully attained at a minimum polymer decomposition cost by the introduction of a suitable amount of 2Na‐p‐PS, 2Na‐p‐HB, or Na‐EMAA or by the concurrent proper incorporation of both of the latter two agents. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 590–601, 2004