热处理对硼酸改性聚乙烯醇体系结构与性能的影响

采用微交联提高改性聚乙烯醇(PVA)热塑加工稳定性,研究了热处理温度和处理时间对微交联改性PVA结构与性能的影响。结果表明:热处理可调控改性PVA体系剩余水含量,改善PVA结晶结构,从而提高力学性能;交联剂硼酸(BA)与PVA形成的交联网络对热处理后的改性PVA力学性能影响显著,BA质量分数为5%,120℃处理90 min后改性PVA拉伸强度增幅达44 MPa,模量增幅达1.30 GPa。     

水凝胶涂层法用于PTFE平板膜的亲水改性研究

采用戊二醛和O-羧甲基壳聚糖(OCMCS)、聚乙烯醇(PVA)在聚四氟乙烯(PVDF)平板膜内进行交联形成一层水凝胶涂层,从而对PTFE平板膜进行亲水改性。考察了反应条件对膜亲水性能的影响和膜的抗污染性能,并对膜表面进行表征。结果表明,水凝胶涂层附着在PTFE纤维表面使膜原纤维变粗,随着PVA含量的增加,改性膜的水通量先增加后减少,接触角先减小后增大,并且当PVA与OCMCS的质量比为1:1,反应时间为6 h、温度为50℃时,膜的性能为优,此时水通量(4 481±80) L/(m~2·h)、接触角57.48°。由于改性膜的表面含有羟基和氨基等官能团,使膜具备良好的抗蛋白质吸附能力;PVA与OCMCS交联形成的物质分子量大,粘附力强,使亲水涂层不易脱落。     

聚乙烯醇/γ-聚谷氨酸多孔水凝胶构建研究

本实验采用天然大分子聚乙烯醇(PVA),γ-聚谷氨酸(γ-PGA)和魔芋葡甘聚糖(KGM)为基材，通过反复冻融的物理交联方法构建出半透明、多孔的聚乙烯醇/γ-聚谷氨酸多孔水凝胶。而后通过改变γ-PGA、KGM、PVA浓度以及pH、反复冻融次数、冷冻温度与冷冻时间等单因素实验，并进行响应面法优化，获得了制备γ-聚谷氨酸/聚乙烯醇多孔水凝胶的最佳工艺。实验结果显示，在γ-PGA、KGM与PVA浓度分别在10%、2.5%以及10%,p H为7，冷冻温度-80℃，冷冻时间4小时，反复冻融次数为3次时，所制得的γ-聚谷氨酸/聚乙烯醇多孔水凝胶拥有最佳的溶胀性能，利用扫描电镜和电子万能材料机检测显示所得凝胶拥有丰富的多孔网络结构和良好的机械性能，其溶胀度可达792.6%并且能保水达48小时，可以满足良好敷料的需求。     

还原氧化石墨烯负载纳米银/聚乙烯醇型抗菌水凝胶的制备与性能

以聚乙烯醇（PVA）、氧化石墨烯（GO）、硝酸银为原料,在不添加引发剂和交联剂的情况下,使用物理交联法（冷冻-解冻法）制得了一系列还原氧化石墨烯（rGO）负载不同质量分数纳米银（AgNPs）/PVA型抗菌水凝胶（rGO-AgNPs/PVA）(PGA-1～PGA-6,阿拉伯数字代表AgNPs的质量分数)。通过FTIR、SEM、TGA、电子万能材料试验机和流变仪对水凝胶的结构、形貌、力学性能和流变性能进行了表征,并对其生物性能进行了测试。结果表明,rGO的加入增强了PVA水凝胶的机械强度,rGO-AgNPs/PVA抗菌水凝胶断裂伸长率比PVA水凝胶提高约60%,拉伸应变达到125%。PVA水凝胶的储能模量和损耗模量均低于rGO-AgNPs/PVA水凝胶;rGO与AgNPs协同抗菌,PGA-3(AgNPs质量分数0.33%)对大肠杆菌和金黄色葡萄球菌的抑菌带宽度分别约为4.5和5.5 mm;相较于PVA水凝胶,rGO-AgNPs/PVA水凝胶的孔洞增多,r GO通过π-π作用形成网络结构,r GO-Ag NPs/PVA水凝胶显示出多孔互联的微观结构。     

聚乙烯醇水凝胶的制备及其溶胀性能

以硼砂为交联剂,采用化学交联法制备了聚乙烯醇(PVA)水凝胶。通过测试PVA水凝胶的溶胀性能,讨论了聚乙烯醇与交联剂的最佳配比,以及盐浓度、温度、交联剂对其溶胀率的影响。结果表明,随着交联剂用量的增加,PVA水凝胶的溶胀率逐渐增大,当达到最大值时,又随着交联剂的增加而降低。随着盐浓度的增加,PVA水凝胶的溶胀率逐降低。PVA水凝胶没有温度敏感性。     

聚丙烯酸钠/聚乙烯醇复合水凝胶的制备及其电响应行为

以过硫酸钾为引发剂,N, N′-二甲基双丙烯酰胺为交联剂结合冷冻-解冻交联,制备了一系列不同配比的聚丙烯酸钠(PAAS)/聚乙烯醇(PVA)互穿网络水凝胶,并用傅里叶红外光谱仪(FTIR)、场发射扫描电子显微镜(SEM)、热失重分析仪(TG)、万能试验机等对其进行表征。结果表明,PVA均匀分散于互穿网络水凝胶中,PVA的加入可以提高PAAS水凝胶的热性能;使PAAS水凝胶的溶胀速率和最大溶胀度减小,在PVA含量达到14%(质量分数,下同)时最低,随后又提高;PVA的加入可以显著提高其力学性能,断裂伸长率和拉伸强度均随PVA含量的增加而增大;PVA的加入提高了互穿网络的电响应灵敏度,且其最佳含量为21%。     

蒽改性聚乙烯醇水凝胶的制备与表征

首先以蒽甲醛和聚乙烯醇(PVA)为原料、二甲基亚砜(DMSO)为溶剂、对甲苯磺酸(TsOH)为催化剂,反应得到蒽接枝改性聚乙烯醇(AnPVA)。然后利用混合溶剂凝胶法制备AnPVA水凝胶。通过差示扫描量热法(DSC)、拉伸等测试,研究水凝胶的力学等性能。结果表明,相比于纯PVA水凝胶,AnPVA水凝胶的力学性能得到了显著提高,在水凝胶中引入疏水基团是一种十分有效提高水凝胶力学性能的手段。AnPVA水凝胶浸泡于水中加热后无明显溶胀,有着优异的耐热和耐水性能,并且该水凝胶是物理交联网络,有着良好的循环重塑性能。     

TDI交联改性聚乙烯醇水性胶粘剂的合成工艺研究

TDI(甲苯二异氰酸酯)交联改性PVA(聚乙烯醇)能明显提高PVA胶粘剂的耐水性和粘接性能。以PVA掺量、羧甲基纤维素(CMC)掺量、交联剂TDI掺量、催化剂-X掺量、交联温度和交联时间为试验因素,压缩剪切强度为考核指标,采用正交试验法优选出合成该改性PVA胶粘剂的最佳工艺条件。研究结果表明:当PVA为12 g/100 m L、CMC为3.2 g/100 m L、φ(TDI)=3%、φ(催化剂-X)=0.4%(均相对于胶粘剂体积而言)、交联温度为30℃和交联时间为45 min时,所合成的单组分TDI改性PVA胶粘剂具有良好的环保性、粘接性,可广泛应用于林产工业、纸品工业以及建筑行业等领域。     

温度及pH敏感性聚乙烯醇/羧甲基壳聚糖水凝胶的制备与性能研究

以聚乙烯醇(PVA)和羧甲基壳聚糖(CMCh)为原料,采用60Co-γ射线辐照交联制备聚乙烯醇/羧甲基壳聚糖(PVA/CMCh)水凝胶;研究了PVA与CMCh的配比、温度、pH及离子强度等对PVA/CMCh水凝胶溶胀率的影响。结果表明适当配比的PVA/CMCh水凝胶具有一定的温度、pH及离子敏感性。该水凝胶在5~20°C时具有较高的溶胀率,温度在20°C以上溶胀率较低,并且有一定的可逆性;水凝胶在pH较低(pH<4.0)和较高(pH>6.0)时溶胀率均较大,而当pH为4.0~6.0时溶胀率较小,显示出一定的pH敏感性。     

聚乙烯醇水凝胶自修复性能

高浓度聚乙烯醇（PVA）水凝胶具有一定的修复功能,但其自修复机理及制备工艺参数对其修复性能的影响缺乏研究。本文采用冷冻-解冻法制备了高浓度自修复PVA水凝胶,通过调整PVA水凝胶制备工艺参数（PVA分子量、PVA浓度、冷冻时间、解冻时间、冷冻-解冻次数、修复时间、冷冻温度等）得到了最佳工艺条件,分析了水凝胶自修复机理,并研究了PVA水凝胶的多次自修复性能。研究结果表明：相对分子质量大的PVA制备的水凝胶自修复性能好;其中冷冻时间为2h,解冻时间为1h,一次冷冻-解冻循环制备得到的水凝胶自修复性能最好,最佳修复时间为12h,能较好地进行反复自修复。指出水凝胶自修复性能主要是由其内部可逆氢键的相互作用形成的,其主要影响源于冷冻-解冻处理后水凝胶内部羟基含量及PVA分子的流动性。     

化学交联对改善聚乙烯醇膜耐水性的研究

以马来酸为交联剂,通过化学交联法改善聚乙烯醇的耐水性能。结果表明随着交联剂浓度的增大,经过交联的PVA耐水性显著增加;PVA的交联度及结晶度主要由热处理温度决定,随着热处理温度的升高PVA膜的溶水率明显下降;当热处理温度确定后,在一定的热处理时间内PVA的分子结构基本达到稳定状态。当MA浓度为6%,热处理条件为160℃、1.5 h时,可获得耐水性较好的PVA膜。     

Comparison the properties of PVA/Na+‐MMT nanocomposite hydrogels prepared by physical and physicochemical crosslinking

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na‐montmorillonite (Na⁺‐MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a freezing‐thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 37:897–906, 2016. © 2014 Society of Plastics Engineers     

淀粉/聚乙烯醇全降解缓释塑料薄膜的制备与性能研究

聚乙烯醇(PVA)溶解后与淀粉(St)共混,同时加入增塑剂丙三醇、交联剂甲醛,反应结束后将包膜液流延成膜。考察了m(St)∶m(PVA)、反应温度、丙三醇用量、甲醛加入方式、甲醛用量、反应时间对薄膜性能的影响,并表征了薄膜的结构。结果表明:当m((St)∶m(PVA)=7∶3、反应温度为90℃、w(丙三醇)=3%(占St、PVA、纯水质量之和的质量分数)、甲醛一次性加入、w(甲醛)=2%、反应时间为1 h时,制得的塑料薄膜拉伸强度、断裂伸长率较大,吸水率和透NH4+率均较低,共混体系的相容性好。     

聚乙烯吡咯烷酮/壳聚糖共混水凝胶的制备与水的状态

以戊二醛作为交联剂,制备了聚乙烯吡咯烷酮（PVP）/壳聚糖（CHI）共混水凝胶,共混物的玻璃化转变温度T_g随CHI含量的升高而升高,SEM图谱观察到PVP/CHI凝胶表面呈现随CHI∶PVP比而变化的微相分离.凝胶溶胀率随着PVP含量升高、PVP分子量降低、CHI脱乙酰度增大而升高.DSC分析表明,非冷冻状态下,CHI∶PVP为1∶2时,游离水、可冻结结合水、非冻结结合水含量分别为42.7%、43.3 %、14.0 %;CHI∶PVP为1∶8时,凝胶中含非冻结结合水少,DSC曲线上只有一个明显的失水吸热峰,由游离水与可冻结结合水叠加而成.-123℃冷冻条件下凝胶的DSC升温曲线在0、38、53℃观察到一组明显的焓化峰,这是由于低温时冻结为结晶相的游离水、可冻结结合水,随温度升高吸热又转化为游离水、可冻结结合水所致.     

Properties of electrospun poly(vinyl alcohol) hydrogel nanofibers crosslinked with 1,2,3,4‐butanetetracarboxylic acid

ABSTRACT: Electrospun nanofibrous hydrogel membranes have been gaining significant importance due to the combination of unique physical properties of nanofibers and biocompatibility of hydrogels. Thus, they are considered as potential candidates for medical textile applications. This study deals with electrospinning of poly(vinyl alcohol) (PVA) hydrogel nanofibrous membranes. The chemical crosslinking of PVA with proportionate quantities of 1,2,3,4 butanetetracarboxylic acid (BTCA) was undertaken to form hydrogel structures. Cross‐linked membranes were characterized by scanning electron microscopy, FT‐IR and thermogravimetric analysis, water swelling, and durability tests. FT‐IR analysis demonstrated the formation of ester linkages between PVA and BTCA and thermogravimetric analysis showed that crosslinking improved the thermal stability of the nanofibrous structure. Furthermore, the results indicated that crosslinking with BTCA improved water stability of PVA membranes and the nanofibrous structure was preserved after water treatment. It is envisaged that use of BTCA as a cross‐linker to form hydrogel nanofibers could be a practical and a promising method for medical textile applications, especially for wound dressings given its nontoxicity and immiscibility with polymer solutions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of crosslinking degree of poly(vinyl alcohol) hydrogel in aqueous solution: kinetics and mechanism of copper(II) adsorption

Recently, a renewed interest in hydrogels for heavy metal removal of wastewater has been growing because of embarking opportunities in industrial applications. One of the most interesting hydrogels potentially used as absorbent is poly(vinyl alcohol) (PVA), owing to its biocompatibility. In this study, the adsorption capacity of copper(II) ion onto PVA hydrogel (PVAH) adsorbents with different crosslinking degrees of 1, 3 and 5 % from aqueous solution was investigated. The PVAH adsorbents were prepared from PVA, using glutaraldehyde as a crosslinking agent. Their properties were determined by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and water absorption measurement. The results showed that PVA was crosslinked with glutaraldehyde. It exhibited an equilibrium swelling ratio in the range of 195–250 %, depending on the crosslinking degree with different PVAH structures defined from SEM micrographs. The adsorption capacity of copper(II) ion onto PVAH adsorbents was investigated and found that higher crosslinking degree decreased the absorption capacity. This behavior is due to the decrease in reactive sites, resulting in the decrease of interaction between copper(II) ion and PVA. Besides, the adsorption capacity also depended on contact time, pH and temperature. The adsorption process followed pseudo-second-order kinetic, having a 0.99 correlation coefficient. Intraparticle diffusion was confirmed by the adsorption mechanism controlled by particle and film diffusions.     

Structure and properties of porous poly(vinyl alcohol) hydrogel beads prepared through a physical–chemical crosslinking method

Porous poly(vinyl alcohol) (PVA) hydrogel beads (PC beads) are potential microorganism carriers applied in wastewater treatment industries. However, improving the mechanical strength and stability of traditional PVA hydrogel beads in water is still a challenge. In this research, a new kind of PC bead was successfully prepared by a combination of physical and chemical crosslinking methods. The structures and properties of the PC beads and conventional PVA beads obtained by individual chemical (boric acid) or physical (cyclic freezing and thawing) processes were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and hydraulic stability testing. Compared with the conventional products, the PC beads displayed a more homogeneous and porous structure, bigger surface area, higher hydraulic stability, and better mechanical properties and showed better applicability for the water treatment field. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46402.     

NCC负载纳米TiO2复合膜的表征

采用交替沉积自组装的方法制备聚乙烯醇（PVA）/纳米纤维素（NCC）-纳米TiO2/PVA复合膜,用傅里叶变换红外光谱（FT-IR）和扫描电子显微镜（SEM）表征,结果表明PVA/NCC-纳米TiO2/PVA复合膜形貌规整,NCC负载纳米TiO2粒子只是物理共混,没有化学键合.性能分析结果表明PVA/NCC-纳米TiO2/PVA复合膜在紫外光区有较强吸收,较高的拉伸强度109.5 MPa,且比PVA膜热稳定性好,热分解温度提高约20℃.     

Controllable synthesis of a novel poly(vinyl alcohol)‐based hydrogel containing lactate and PEG moieties

Tunable hydrogel that contained well‐defined poly(vinyl alcohol) (PVA), labile lactate groups, and hydrophilic poly(ethylene glycol) (PEG) segments was prepared through a combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and esterification reaction. A diol was prepared via the esterification between lactic acid (LA) and PEG. Then the diol was allowed to react with maleic anhydride to produce a diacid. Meanwhile, well‐defined PVA was synthesized by the alcoholysis of poly(vinyl acetate) (PVAc) obtained by RAFT polymerization of vinyl acetate. The hydrogels with tailor‐made structure were generated by crosslinking PVA with LA‐based diacid. The structures and properties of LA‐based intermediates and the hydrogels were characterized with Fourier transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Both LA‐based diol and diacid were semicrystalline and water‐soluble, their melting temperature and glass transition temperature were 52 and ?51, 54 and ?41°C, respectively. The polydispersity indexes of the precursor of PVA samples were within the range of 1.03–1.10. It was found that the thermal stability of hydrogel was higher than that of LA‐based diacid. Both the swelling and release properties of the hydrogels depend on the feeding ratio of PVA/LEM and the chain length of PVA, which reflected that the structure and properties of the hydrogels were controllable. POLYM. ENG. SCI., 54:1366–1371, 2014. © 2013 Society of Plastics Engineers     

Synthesis,characterization and efficacy of chemically crosslinked PVA hydrogels for dermal wound healing in experimental animals

In this study, we have investigated the efficacy of crosslinked polyvinyl alcohol (PVA) hydrogel as a wound dressing material, using rat as the animal model. The hydrogel was synthesized by chemical crosslinking of PVA with potassium persulphate and the crosslinking reaction parameters were optimized. The developed hydrogel was found to possess excellent mechanical properties, high water absorption capacity, gel content, and optimum water vapor transmission rate, indicating its ability to act as an effective wound dressing material. The inherent nontoxic characteristics of PVA remained unaltered after crosslinking. The in vitro diffusion studies of bovine serum albumin (BSA) as model protein, indicated a relatively slow release of protein resulting from its microencapsulation in the polymeric matrix. For in vivo studies, full‐thickness excision wounds (2 × 2 cm²) were made on the dorsal surface of rats. The hydrogel was applied on the wound and changed at regular intervals. For comparison of wound healing ability, a radiation crosslinked PVA‐based hydrogel, “HiZel” was used as a reference control. The wounds treated with PVA hydrogel healed faster as indicated by an increased rate of wound contraction (16.5 days versus 22.0 in control group). Treatment with “Hizel” led to increase in hydroxyproline in the wound tissue, whereas treatment with PVA hydrogel led to increase in both hydroxyproline as well as hexosamine. This probably provides added strength to the tissue, thereby indicating that PVA hydrogel had higher efficacy than “Hizel”. The results suggest that chemically crosslinked PVA hydrogel could be used as an effective wound dressing material. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009