复配增塑剂改性聚乙烯醇的热塑加工性能研究

以甘油/二缩三乙二醇(GP)为主增塑剂,N-甲基吡咯烷(NMP)辅助增塑剂,对聚乙烯醇(PVA)进行增塑改性,研究了增塑剂类别和配比对PVA的增塑效果。通过红外光谱分析(FTIR)研究了复配增塑剂与PVA间的相互作用,采用X射线衍射分析(XRD)、差示扫描量热分析(DSC)、热失重分析(TGA)表征了改性PVA的结晶性能和热性能,采用熔融指数仪和转矩流变仪研究了改性后PVA的热塑加工性能。结果表明:复配增塑剂能有效地破坏PVA自身的氢键,降低PVA的熔融温度和结晶度,改善PVA的热塑加工性能,并成功实现了改性PVA的注塑成型。通过注塑成型的PVA具有较好的力学性能,拉伸强度为28.6 MPa,断裂伸长率为534%。     

PVA增塑性能正交试验研究

利用正交试验设计增塑剂与聚乙烯醇(PVA)共混配方,并进行熔融共混模压成型制备增塑PVA薄膜,通过对薄膜的力学性能、熔点、耐水性等性能进行测试,运用正交试验法研究复配增塑剂配方中蒸馏水、甘油、己内酰胺和二甲基亚砜的用量对薄膜拉伸强度、熔点和吸水率的影响。结果表明:增塑改性PVA的复配增塑配方中己内酰胺对拉伸强度影响程度最大,蒸馏水对熔点和吸水率的影响较大。较优的改性PVA复配增塑剂配方为:蒸馏水10 g,甘油10 g,己内酰胺20 g,二甲基亚砜8 g。     

聚甘油增塑改性聚乙烯醇复合膜性能研究

以聚甘油(PG)为增塑剂,采用溶液流延法制备了PG增塑改性聚乙烯醇(PVA)复合薄膜。通过红外光谱分析(FTIR)、X射线衍射分析(XRD)、差示扫描量热分析(DSC)、热失重分析(TGA)、拉伸测试等考察了PVA/PG复合膜的氢键作用、结晶性能、热性能、力学性能。结果表明:PG增塑剂能有效破坏PVA自身的氢键,在PVA热分解温度基本保持不变的前提下降低材料的熔融温度和结晶度,从而扩展PVA的热塑加工温度窗口。随着PG用量的增加,PVA/PG复合薄膜的拉伸强度逐渐降低,而断裂伸长率明显提高。     

复合增塑体系对聚乙烯醇加工性能的影响

为实现聚乙烯醇(PVA)的熔融加工成型,将不同聚合度的2种PVA共混,并分别加入甘油/增塑剂1或甘油/增塑剂2复合增塑剂。X射线衍射仪、差示扫描量热仪及热失重分析仪等测试结果表明,复合增塑体系的加入使PVA的结晶度降低,熔点从225℃降低到206℃,热分解温度基本不变,PVA热塑性加工有望得到实现。     

长链乙烯酯改性聚乙烯醇热塑加工性能的研究

通过山梨醇和甘油复配增塑改善长链乙烯酯改性聚乙烯醇(PVA)的热塑加工性能,采用差示扫描量热仪、高压毛细管流变仪、万能试验机等研究了复配增塑剂与改性PVA的相互作用及其对改性PVA热性能、流变性能、力学性能、溶胀性能等的影响。结果表明,山梨醇和甘油复配增塑剂中的羟基可与改性PVA分子链中的羟基形成氢键,减小了PVA分子链间氢键相互作用,使体系黏度减小,分子链的活动性增强,降低了改性PVA熔点,改善了PVA熔体流动性,有利于实现PVA的热塑加工。复配增塑剂增加了PVA的自由体积,使PVA分子链的运动更加容易,提高了材料的柔韧性及断裂伸长率,减少PVA对水的吸收。当增塑剂含量为10%时,复配增塑剂不易析出,可同时改善改性PVA的流变性并使材料保持优异的力学性能。     

聚乙烯醇吹膜加工性能研究

研究了聚乙烯醇(PVA)吹膜加工性能。经两种不同的增塑剂复配增塑后，可明显改善其加工流动性，当复合增塑剂用量为25phr以上，PVA可以被较好地增塑，熔融塑化温度趋于定值。热性能研究表明，PVA为不完全结晶，其熔融曲线呈不规则分布。从PVA的流变性能可知，PVA熔体呈非牛顿性流体，剪切粘度随剪切速率增加而下降，并且醇解度较高的树脂，剪切粘度也较高。不同醇解度的PVA树脂，均能通过增塑改性后熔融挤出加工吹塑成膜。高醇解度PVA膜的水溶解温度高，而低醇解度PVA膜具有低温快速水解的性能。     

淀粉/三聚氰胺增塑PVA熔融加工膜的制备及性能

以淀粉/三聚氰胺为复配增塑剂,利用熔融加工工艺制备聚乙烯醇(PVA)膜,采用差示扫描量热(DSC)、热失重分析(TG)和力学性能测试等考察了增塑剂含量对PVA膜性能的影响.结果表明,复配增塑剂能有效破坏分子链间氢键,对PVA的增塑作用明显.随增塑剂含量增大,PVA膜的力学性能和熔体质量流动速率呈先增大后减小的趋势,熔点...     

己内酰胺/氯化镁复配增塑聚乙烯醇的性能研究

采用己内酰胺/氯化镁为复配增塑剂,通过流延法制备出了增塑改性的聚乙烯醇(PVA)膜。采用DSC、TGA、XRD分析和力学性能与熔体流动性能测试的方法考察了己内酰胺/氯化镁复配增塑剂对PVA性能的影响。结果表明:氯化镁与己内酰胺复配具有良好的协同增塑效应,其对PVA的增塑效果优于单独使用己内酰胺;复配增塑剂能够有效破坏PVA分子间的氢键,降低PVA的结晶度;加入复配增塑剂后,PVA的熔点降低,热稳定性提高,熔体流动性有所改善,拉伸强度降低,断裂伸长率上升。     

氯化锂增塑改性聚乙烯醇的研究

以氯化锂(LiCl)为增塑剂,采用流延法制备增塑改性聚乙烯醇,通过红外光谱(FTIR)、差示扫描量热仪(DSC)、热重分析仪(TGA)和电子万能试验机研究氯化锂对改性聚乙烯醇分子间作用、热性能和力学性能的影响。结果表明,氯化锂与PVA分子间相互作用,破坏PVA的结晶度和结晶结构,降低改性PVA体系的熔点。部分氯化锂可以增加PVA的热稳定性。随着氯化锂含量的增加,改性PVA体系塑性增加,拉伸强度逐渐降低,断裂伸长率逐渐增加。     

碳酸钙高填充聚乙烯醇复合材料热塑加工性能研究

采用分子复合和增塑,以水、多元醇和含酰胺基团化合物组成复配增塑剂,通过热塑加工制备了碳酸钙(CaCO3)高填充聚乙烯醇(PVA)复合材料,采用差示扫描量热仪(DSC)、热重分析(TG)、高压毛细管流变仪等研究了复合材料的热性能、流变性能,探讨了复合材料中增塑剂的迁移率及其对制品尺寸稳定性的影响。结果表明,通过分子复合和增塑后,改性PVA及PVA/CaCO3复合材料获得较宽热塑加工窗口,当CaCO3含量为70%时热塑加工窗口达85.5℃;PVA/CaCO3复合材料的熔体为假塑性流体,其黏度满足传统挤出或注塑加工的黏度需要;随环境湿度增加,复合材料中增塑剂迁移率增加,CaCO3可抑制复合材料中增塑剂的迁移,一定程度上提高了复合材料的尺寸稳定性。     

PVA/TPU共混材料热塑加工性能及相容性的研究

采用热塑加工方法制备了聚乙烯醇/热塑性聚氨酯(PVA/TPU)共混材料,系统研究了共混材料的热塑加工性能、相容性及力学性能。结果表明:TPU的引入对共混材料的熔点影响不大,但其与PVA间的氢键作用可屏蔽PVA的羟基,较大幅度地提高了PVA初始热分解温度,获得更宽的热塑加工窗口;引入适量的TPU还可降低共混材料的熔体黏度,改善材料的热塑加工性能,另外,还可获得良好的材料相容性;随着TPU用量的增加,共混材料的拉伸强度先增后降,并在TPU用量为50 phr时达到最大值。     

Water states and thermal processability of boric acid modified poly(vinyl alcohol)

To further improve the processability of water plasticized poly(vinyl alcohol) (PVA), boric acid (BA), which can rapidly form reversible crosslinked structure with the hydroxyl groups of PVA, was adopted as a modifier, and the water states, thermal performance, and rheological properties of modified PVA were investigated. The results showed that ascribing to the formation of the crosslinked structure between PVA and BA, the content of nonfreezing water in system increased, indicating that the bondage of PVA matrix on water enhanced, thus retarding the tempestuous evaporation of water in system during melt process and making more water remained in system to play the role of plasticizer. Meanwhile, this crosslinked structure shielded part hydroxyl groups in PVA chains, leading to the further weakening of the self‐hydrogen bonding of PVA, and guaranteeing a lower melting point and higher decomposition temperature, thus obtaining a quite wide thermal processing window, i.e., ≥179°C. The melt viscosity of BA modified PVA slightly increased, but still satisfied the requirements for thermal processing, thus reinforcing the flow stability of the melt at high shearing rate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43246.     

Structural performance of alkali/acid-ultrasound modified Agave fibers during the melt mixing process with polyvinyl alcohol

This study aims to investigate changes in the structural properties of alkali/acid-ultrasound modified Agave fibers and their performance immersed on a polyvinyl alcohol (PVA) matrix with plasticizer during melt mixing processing. Structural analysis revealed that ultrasound enhances the effectiveness of the conventional alkaline/acid treatments to modify fibers since the simultaneous treatment increased the partial removal of lignocellulosic components, water molecules, and amorphous regions which improved their processability on a PVA matrix. Specific energy consumption values indicated that during melt mixing the modified fibers required more energy to expose the chains of cellulose fraction to function as an interaction site for PVA chains. Once the mixture was homogenized, the fiber-matrix interactions promoted high viscosity, friction, and mechanical stress in the chamber. Therefore, the modified fibers restricted the interaction between plasticizer and PVA in the obtained films, resulting in a highly structured, and reinforced network, increasing the storage modulus as dynamic mechanical analysis indicated. These findings highlight a feasible way to valorize Agave fibers and allow the understanding of the matrix-fiber interactions during melt mixing processing, useful to predict the structural and mechanical properties of the films.     

Thermal processability and properties of highly filled poly(vinyl alcohol)/talc composite

Abstract

A highly filled PVA/talc composite was prepared through our invented thermal processing technology without using any coupling agent or compatibiliser. The results showed that compared with neat PVA, the melt temperature of the composite decreased and the degradation temperature increased, providing a big temperature window for thermal processing of PVA/talc composite. The composite melt exhibited shear thinning behaviour while its viscosity increased with increasing talc, still satisfied the requirement of thermal processing. The morphology analysis confirmed that talc was well dispersed in PVA, improving heat deflection temperature (HDT), tensile strength and modulus of PVA. When talc was 50 wt-%, the HDT, tensile strength and modulus of the composite were 115°C, 48 MPa, 1·23 GPa respectively, increased by 92, 16 and 150%, compared with PVA, and the elongation at break was 100% of the composite, confirming that the high filled PVA/talc composite was a novel PVA based material with excellent thermal and mechanical properties.     

尿素/甲酰胺复配增塑聚乙烯醇薄膜的制备及性能研究

以尿素/甲酰胺为复配增塑剂,采用熔融共混法制备聚乙烯醇（PVA）薄膜。通过傅里叶变换红外光谱、扫描电子显微镜、差示扫描量热仪以及力学测试对PVA薄膜的结构与性能进行表征。结果表明,尿素/甲酰胺复配增塑剂通过破坏PVA分子内与分子间的氢键而影响了PVA分子链的有序结构,在改善PVA加工性能的同时降低了PVA的结晶度,并有效提高了薄膜的韧性。     

Dopamine‐functionalized poly(vinyl alcohol) elastomer with melt processability and self‐healing properties

A dopamine‐functionalized poly(vinyl alcohol) (PVA) elastomer with melt processability and self‐healing properties was prepared by a new chemical route of graft modification, that is, PVA carboxylation and a carbodiimide reaction. The conventional modifier for PVA sacrificed the intrinsic hydrogen‐bonding interactions and dramatically decreased the mechanical strength. The modifier dopamine, as a catechol derivative, has two hydroxyl groups, which formed hydrogen bonds with the hydroxyl groups of PVA; it also has one benzene ring, which increased the thermal stability. We found that the introduction of dopamine into the PVA molecular structure lowered the melting point, improved the thermal stability, broke the crystalline structure, and enabled thermal processing. Moreover, the modified PVA possessed good mechanical properties, could be self‐healed, and is believed to have potential applications in many fields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45072.     

Structure and properties of highly filled poly (vinyl alcohol)/talc composites prepared through thermal processing: effects of talc size

Poly (vinyl alcohol) (PVA), a multi-hydroxyl polymer with excellent comprehensive properties, is an expected candidate to prepare high-performance polymer-based composites without using any coupling agents or compatibilisers. However, the poor thermal processability of PVA is its biggest obstacle. In this paper, by adopting polyol as a plasticiser, highly filled PVA/talc composites with good mechanical properties were successfully obtained through melt extrusion and injection, and the effects of talc size on structure and properties of the composites were studied. The results showed that talc highly filled PVA composites had satisfying melt processability, and the decrease of talc particle size increased the –OH groups on the edges of the talc layers, thus improving the compatibility between talc and PVA, and making talc particles dispersed more uniformly in PVA matrix. As a result, the composites with smaller talc particles had the higher threshold filler concentration to form the filler networks and the better flow behaviour. The smaller talc flakes also exhibited higher orientation in PVA matrix and induced more PVA molecular chains to orient along the melt flow direction, leading to the enhancement of the mechanical properties of the composites.     

Melt processing of poly(vinyl alcohol) through adding magnesium chloride hexahydrate and ethylene glycol as a complex plasticizer

The melt processing of poly(vinyl alcohol) (PVA) was achieved using magnesium chloride hexahydrate (MgCl₂·6H₂O) and ethylene glycol as a complex plasticizer. The interaction between the complex plasticizer and PVA was studied by Fourier transform infrared spectroscopy (FT‐IR). The PVA films were characterized using X‐ray diffraction (XRD), differential scanning calorimetry, thermogravimetric analysis (TGA), scanning electron microscope, and dynamic thermomechanical analysis (DMA) techniques. The band shift of the observed peak around 3335 cm^?1 in the FT‐IR spectra indicates that the complex plasticizer MgCl₂·6H₂O and ethylene glycol could form strong interactions with PVA and thus interrupt the intermolecular and intramolecular hydrogen bonding in PVA. The XRD results show that the addition of the complex plasticizer would significantly destroy the crystallites of PVA and result to the decrease of the degree of crystallinity of PVA. The melting point was reduced from 229°C of pure PVA to around 170°C after the plasticization. The TGA studies show that with the complex plasticizer, the thermal stability of PVA is improved. PVA plasticized by 30 wt% MgCl₂·6H₂O and 10 wt% ethylene glycol shows the tensile strength of 33 MPa and the elongation at break of 362%. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers