在超声波辐照作用下聚乙烯醇的降解及与丙烯腈共聚反应的研究

本文研究了超声波辐照下聚乙烯醇(PVA)在水溶液中的降解规律,结果表明PVA在水溶液中的超声降解速率遵循Baramboim动力学方程.本文还研究了丙烯腈(AN)与PVA在水溶液中的超声波辐照共聚反应.改变超声辐照时间或溶液中AN的量,可得到水溶性和水不溶性两类共聚物.用IR、MS、PGC和X-射线衍射研究了共聚物的结构,证明所得产物主要为嵌段共聚物.在2%的PVA/AN(1/1.6,质量比)水溶液中,以频率为21.5kHz、声强为490W的超声波在20±1℃下辐照28min,水溶性共聚物产率[共聚物产率=(共聚物重/PVA加入量)×100%〕为25.49%,共聚物中AN含量为13.98%;在相同条件下,对2%的PVA/AN(1/4,质量比)水溶液,辐照100min,水不溶性共聚物产率为296.01%,共聚物中AN含量为75.56%.     

Thermal characteristics of poly(ethylene terephthalate) fiber grafted with poly(vinyl acetate) and poly(vinyl alcohol)

Poly(ethylene terephthalate) (PET) fibers were grafted with poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA). The effects of graft copolymers PVAc and PVA on morphological properties of PET were evaluated by differential thermal analysis, differential scanning calorimetry, and thermogravimetric analysis. Melting temperature, heat of fusion, and mass fractional crystallinity of PET was not affected by graft PVAc and PVA. No individual glass transition and melting points corresponding to the graft PVAc and PVA were observed, indicating thereby that graft copolymer mainly exists in the form of free chains inside the PET matrix. Poly(vinyl alcohol) graft copolymer degraded at much lower temperatures than poly(vinyl alcohol) in powder form. Thermal stability of PET fiber was not affected by graft PVAc, where as PET–g–PVA showed an additional degradation point at 360°C.     

Studies on fibers spun from poly(vinyl alcohol‐b‐acrylonitrile) emulsions prepared by ultrasonic technique. I. Characterization of fiber structure

The structural characteristics of poly(vinyl alcohol‐b‐acrylonitrile) fibers with different AN contents were studied by comparison with that of PVA and PAN fibers. X‐ray diffraction analysis showed that both PVA and PAN blocks in the copolymer fibers formed crystals. Two glass transition temperatures corresponding to PVA and PAN components appeared on the dynamic mechanical spectrum of the copolymer fiber, indicative of their incompatibility in the fiber. SEM intuitively exhibited a longitudinal cracked and grooved surface morphology similar to that of PAN fiber and revealed an internal microdomain separation morphology for the block copolymer fibers. TEM showed a morphological structure intermediate between those of PVA and PAN fibers for the block copolymer fibers. It was also found that the copolymer fiber with the lower AN content has a sheath–core structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 979–988, 2001     

吸水膨胀弹性体PVA-g-PBA的研究

在水介质中.在氮气保护下以硝酸铈铵(CAN)为引发剂,将丙烯酸丁酯(BA)接枝到聚乙烯醇(PVA)上,制得水膨胀弹性体PVA—g—PBA。通过红外光谱证实了接枝物的形成。讨论了PVA浓度、单体浓度、引发剂浓度和反应温度对接枝物接枝率(G％)的影响。结果表明随PVC浓度增大,接技率降低.[PVA2.5×10-4mol/L.[BA]0.702mol/l、[CAN]0.01mol/L45℃接枝率较高.接枝率越高其吸水膨胀率越低,8h达吸水平衡,最大吸水率为165.1％。     

Sorption of dye wastes by poly(vinyl alcohol)/poly(carboxymethyl cellulose) blend grafted through a radiation method

The instability in water of poly(vinyl alcohol) (PVA)/poly(carboxymethyl cellulose) (CMC) was improved through radiation-induced grafting with a styrene monomer. The PVA/CMC blend graft copolymer was used as a sorbent for dye wastes normally released from textile factories. The factors that may affect the sorption process such as time, temperature, weight of the blend graft copolymer, and volume of the dye waste were investigated. The sorption of dyestuffs by the blend graft copolymer was determined by a method based on spectroscopic analysis. The results showed that the blend graft copolymer has a high affinity for basic, acid, and reactive dyes. Meanwhile, it was observed that the sorption of dyes is more effective at the high temperature of 70^oC. Moreover, it was found that the sorption of dyes depends on the weight of the blend graft copolymer and does not depend on the volume of the waste solution. The sorption of the dyestuffs by a PVA/CMC graft copolymer may be considered to be a practical method to remove organic pollutants. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 136–142, 2001     

低固含量聚醋酸乙烯乳液黏度影响因素研究

采用半连续种子乳液聚合法制备了固含量为20%的聚醋酸乙烯(PVAC)乳液,探讨了保护胶体聚乙烯醇(PVA)用量、共聚单体、加料方式及轻质碳酸钙(CaCO_3)用量对该乳液黏度的影响。结果表明:随着PVA用量的增加,乳液黏度提高;共聚单体的种类对乳液黏度有一定的影响;乳液黏度随种子单体用量的增加而降低;加入轻质CaCO_3后,乳液的黏度增加数倍。合成乳液的固含量为18.04%,黏度为5 570 mPa·s。     

Preparation of hydrophilic woven fabrics: Surface modification of poly(ethylene terephthalate) by grafting of poly(vinyl alcohol) and poly(vinyl alcohol)-g-(N-vinyl-2-pyrrolidone)

One of the most industrially important synthetic textile materials, woven poly(ethylene terephthalate) (PET) fabrics, have limitations in the usage of casual apparel applications due to their unwanted hydrophobicity. For that reason, in this study, to impart permanent hydrophilicity to the PET fabrics, hydrophilic poly(vinyl alcohol) (PVA) and a PVA-based copolymer were introduced to the alkaline hydrolysis pretreated PET surface by graft copolymerization for the first time. The graft modification of PET fabric surface was performed with an industrial-adaptable approach. The synthesis of a novel PVA-g-(N-vinyl-2-pyrrolidone) copolymer was achieved by the introduction of glycidyl methacrylate monomer to the PVA backbone. The structure of the copolymer was evidenced by attenuated total reflection–Fourier transform infrared spectroscopy and ¹H-NMR techniques. The introduction of PVA and copolymer structures with desired functional groups to the PET fabric surface was confirmed with the X-ray photoelectron spectroscopy technique. It was obtained that the contact angle–wetting time of PET fabric (145° and 98 s) could be dropped to 37° and 0.1 s and 64° and 0.7 s after PVA and copolymer grafting, respectively. This suggests that the graft-modified PET fabrics may find the potential of use in the textile applications as the alternative hydrophilic materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48584.     

Drug‐release behavior of chitosan‐g‐poly(vinyl alcohol) copolymer matrix

Chitosan‐g‐poly(vinyl alcohol) (PVA) copolymers with different grafting percent were prepared by grafting water‐soluble PVA onto chitosan. The drug‐release behavior was studied using the chitosan‐g‐PVA copolymer matrix containing prednisolone in a drug‐delivery system under various conditions. The relationship between the amount of the released drug and the square root of time was linear. From this result, the drug‐release behavior through the chitosan‐g‐PVA copolymer matrix is shown to be consistent with Higuchi's diffusion model. The drug‐release apparent constant (K_H) was slightly decreased at pH 1.2, but increased at pH 7.4 and 10 according to the increasing PVA grafting percent. Also, K_H was decreased by heat treatment and crosslinking. The drug release behavior of the chitosan‐g‐PVA copolymer matrix was able to be controlled by the PVA grafting percent, heat treatment, or crosslinking and was also less affected by the pH values than was the chitosan matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 458–464, 1999     

聚丙烯酸酯-聚甲基丙烯酸缩水甘油酯自交联共聚物乳液的结构及性能表征

以过硫酸钾为引发剂,聚乙烯醇为高分子分散剂,甲基丙烯酸缩水甘油酯(GMA)为交联剂,采用种子无皂乳液聚合方法制备了丙烯酰胺(AM)、丙烯酸(AA)、丙烯腈(AN)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)共聚的自交联聚丙烯酸酯-聚甲基丙烯酸缩水甘油酯共聚物。用TEM、FTIR、XRD、DSC对共聚合物乳液的粒子形态及聚合物的结构进行了表征,通过SEM观察了纸张表面及断面的微观结构。结果表明,用GMA作交联剂,可制备稳定的自交联聚丙烯酸酯-聚甲基丙烯酸缩水甘油酯共聚物乳液;该聚合物属于非晶态聚合物,且经GMA交联后形成的网络聚合物强度大大增加;当w(GMA)=0.7%,w(PVA)=4%时,可使纸张干强度指标:环压指数、耐破度、抗张指数相对空白原纸分别提高约32%、95%、25%。     

PVA/ P（AA-Co-AN）/ PVA渗透汽化膜的研究

制备一种PVA/P(AA-Co-AN)/PVA复合膜用于甲醇水溶液的分离,膜的主体部分P(AA-Co-AN)由添加纳米S iO2粉末的丙烯酸(AA)和丙烯腈(AN)通过溶液共聚制得,两侧为交联聚乙烯醇(PVA)。考察了复合膜在高质量分数甲醇水溶液中的溶胀性能,探讨了浸泡液温度及浸泡液质量分数对溶胀度的影响,测试了复合膜的力学性能。考察了不同单体配比〔n(AA)∶n(AN)〕所制备的复合膜在不同质量分数甲醇水溶液,不同温度下的渗透汽化性能。结果显示,复合膜在高质量分数甲醇水溶液中具有良好的溶胀性能及渗透汽化性能;在n(AA)∶n(AN)=1∶1下所制备的复合膜,对高质量分数甲醇水溶液分离效果最佳,60℃时分离w(甲醇)=98%的水溶液,分离因子可达1 534,通量为583 g/(m2.h)。     

PLLA/PVA/PLCA三元共混体系分子间相互作用

聚L-乳酸(PLLA)及聚乙烯醇(PVA)由于其良好的生物相容性,在生物医学领域得到了广泛的关注。但聚乳酸由于其疏水性及缺乏反应位点而使其应用受到一定的限制。将聚乙烯醇与聚乳酸共混,不仅可以降低聚乳酸的成本,同时可以改善其亲水性,但由于其结构差异,存在严重的相分离现象。本研究将含有反应活性位点的乳酸-柠檬酸共聚物(PLCA)引入PLLA/PVA体系中,以期改善二者的相容性。通过红外光谱分析手段,研究了PLLA/PVA/PLCA体系中分子间的相互作用,并对不同组成体系的力学性能进行了分析及表征。结果表明,PLCA的加入使PLLA/PVA复合体系的相容性及力学性能得到了明显的改善。     

Synthesis of boronate-containing copolymers of N,N-dimethylacrylamide, their interaction with poly(vinyl alcohol) and rheological behaviour of the gels

Cross-linking of polyvinylalcohol (PVA) by boronate-containing copolymer of N,N-dimethylacrylamide (DMAA, 1) was studied and compared to cross-linking of PVA by borate buffers in weakly alkaline solutions. The copolymer of M_w=19,000 g mol⁻¹ containing 9 mol% N-acryloyl-m-aminophenylboronic acid (NAAPBA, 2) was prepared by free radical polymerization of the monomers, exhibiting copolymerization constants r₁=0.84 and r₂=2.2. Due to multipoint interaction of the copolymer with PVA via monodiols, the intermolecular cross-linking required for seven-fold and 10-fold lower boron concentrations as compared to borate buffers of pH 8.6 and 7.5, respectively. In rheological measurements, PVA-copolymer gels exhibited storage moduli (G′_max) comparable to those of PVA-borate gels prepared at 7.5-fold higher boron concentration and the same pH 8.6, what testified to the similar concentration of cross-links in the gels. Therefore, DMAA-NAAPBA copolymer is a more effective cross-linker of PVA than borate. The PVA-copolymer gel exhibited much higher relaxation time (97 s) compared to PVA-borate gels (≤20 s) indicating a longer lifetime of junction zones. The ‘shape stability’ of the gel is suggested to originate in the structure of junctions, containing several boronate-diol complexes, between the macromolecules of PVA and the copolymer.     

两亲性接枝共聚物PVA-g-PBA的合成与表征

以过硫酸钾 (KPS)为引发剂 ,将丙烯酸丁酯 (BA)接枝到聚乙烯醇 (PVA)上 ,制得两亲性接枝共聚物 PVA-g-PBA。用红外光谱、X射线衍射表征了接枝物 ,研究了引发剂浓度、单体浓度及反应时间对单体转化率、接枝率和接枝效率和接枝率对共聚物吸水性能的影响。结果表明在水介质中 ,氮气保护下 ,70℃时 ,以过硫酸钾 (KPS)为引发剂 ,将丙烯酸丁酯 (BA)接枝到聚乙烯醇 (PVA)上 ,[PVA]为 2 .5× 1 0 -4mol/ L,[BA]为 0 .63 mol/ L、[KPS]为 5 .5 5× 1 0 -4时 ,反应 5 h,能获得较高 CM、G和 Ge的接枝物。接枝物的接枝率越高 ,吸水率越低 ,吸水 1 0 h达平衡 ,最大平衡吸水率为 1 88.8%。     

Characterization of hydrogels based on chitosan and copolymer of poly(dimethylsiloxane) and poly(vinyl alcohol)

Copolymers composed of poly(vinyl alcohol) (PVA) and poly(dimethylsiloxane) (PDMS) were crosslinked with chitosan to prepare semi‐interpenetrating polymer network (IPN) hydrogels by an ultraviolet (UV) irradiation method for application as potential biomedical materials. PVA/PDMS copolymer and chitosan was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2‐dimethoxy‐2‐phenylacetophenone as a nontoxic photoinitiator by UV irradiation. Various semi‐interpenetrating polymer networks (semi‐IPNs) were prepared from different weight ratios of chitosan and the copolymer of PVA/PDMS. Photocrosslinked hydrogels exhibited an equilibrium water content (EWC) in the range of 65–95%. Swelling behaviors of these hydrogels were studied by immersion of the gels in various buffer solutions. Particularly, the PCN13 as the highest chitosan weight ratio in semi‐IPN hydrogels showed the highest EWC in time‐dependent and pH‐dependent swelling. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2591–2596, 2002     

Mechanical properties,water swelling behavior,and morphology of swellable rubber compatibilized by PVA‐g‐PBA

A novel water swellable rubber (WSR) was prepared by blending chlorohydrin rubber (CHR) with crosslinked polyacrylate (CPA), poly(vinyl alcohol)‐g‐poly(butyl acrylate) (PVA‐g‐PBA), precipitated silica (PSA), and poly(ethylene glycol) (PEG). The amphiphilic graft copolymer PVA‐g‐PBA was incorporated as the compatibilizer between CHR and CPA. Water swellable‐rubber with different grafting percentages and contents of PVA‐g‐PBA was investigated by SEM, mechanical measurement, and water‐swelling tests. The results prove that PVA‐g‐PBA increased interfacial cohesion between CHR and CPA before and after water swelling, decreased percentage loss by weight, and improved water‐swelling behavior. Mechanical properties of WSR were significantly improved by PVA‐g‐PBA, especially for the blends of 5 phr PVA‐g‐PBA with G% = 151.7% before water swelling and that with G% = 340.4% after water swelling.     

Morphology of polyurethane modified by plasticizing,blending, or reinforcing

The morphology of modified thermoplastic PU has been studied by SEM and DSC. The PU was modified by addition of various amounts of dibutyl phthalate (DBP) plasticizer, vinyl polymers (PVA, PVAc, PVC, VAc–VC copolymer), polysiloxane or fiber reinforcement (glass or cotton) to diolpolyether, followed by mixing and vigorous stirring with dephenylmethane diisocyanate. SEM observations indicated that PU and its modifications have a cellular (foam) structure. A homogeneous matrix was observed in binary blends of PU and DBP in ratios of 20:1 down to 6.6:1; PVA, PVAc, VAc–VC copolymer with a weight ratio of 40:1, PU containing glass fiber (20:1) or cotton fiber (40:1). Blends of PU—with PVA at a weight ratio of 20:1, with PVC in ratios from 20:1 down to 5:1, or with polysiloxane polymer—were heterogeneous and thus not miscible, as evidenced by SEM observations. With the exception of the PU—PSO mixtures, the thermal behavior of the heterogeneous blends did not permit any conclusion regarding miscibility.     

Rheological properties of solutions of graft copolymers of polyvinyl alcohol and polyacrylic acid

Conclusions The activation energy of viscous flow of systems containing the PVA-PAA graft copolymer is considerably higher than that for solutions of PAA; the activation energy of viscous flow of solutions of mechanical mixtures of PVA and PAA is higher than that of mixtures of PVA with the graft copolymer. This fact is a convincing confirmation of the compatibility of the PVA-(PVA-PAA) graft copolymer system.The compatibility of this system is also shown by the high stability of the solutions. Thus, 12.5% solutions of the mixture of PVA and the graft copolymer in a ratio of 4/1 do not separate into layers during 3–4 days. The achievement of the compatibility of a mixture of the polymers mentioned by grafting is an important advantage obtained by the modification of polymers by the method of graft copolymerisation.All-Union Correspondence Institute of the Textile and Light Industries. Translated from Khimicheskie Volokna, No. 2, pp. 27–29, March–April, 1969.     

Studies on fibers spun from poly(vinyl alcohol‐b‐acrylonitrile) emulsions prepared by ultrasonic technique. II. Properties of the fibers

The moisture content of poly(vinyl alcohol‐b‐acrylonitrile) fibers decreases with an increasing hydrophobic AN content and crystallinity of the fibers; however, the copolymer fiber with 26.94% AN, drawn × 5, and heat‐treated at 200°C has a moisture content value slightly lower than that of commercial PVA fiber, but much higher than that of commercial PAN fiber. The block copolymer fibers have a water‐retention value higher than that of commercial PVA fiber, owing to the presence of voids in these fibers, and have a stronger wicking ability than that of commercial PVA, PAN fibers, and wool and cotton mainly due to the grooved surface and bulk porous morphology of the fibers. The tensile strength of the copolymer fibers with an appropriate AN content are lower than that of commercial PVA fiber, but higher than that of commercial PAN fiber and much higher than that of wool and cotton. The melting temperatures of the copolymer fibers increase with increasing heat‐treatment temperature. The copolymer fibers possess a lower peak cyclizing temperature than that of the PAN fiber and have a higher thermal stability than that of both PVA and PAN fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 989–994, 2001     

Thermal,structural, and optical properties of γ‐irradiated poly(vinyl alcohol)/poly(ethylene glycol) thin film

Poly(vinyl alcohol)/poly(ethylene glycol) (PVA/PEG) copolymer was prepared using casting technique. The obtained PVA/PEG thin films have been irradiated with gamma rays with doses ranging from 1.5 to 20 Gy. The resultant effect of gamma irradiation on the thermal properties of PVA/PEG has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The onset temperature of decomposition T_o and activation energy of thermal decomposition E_a were calculated, results indicating that the PVA/PEG thin film decomposes in one main weight loss stage. Also, the gamma irradiation in dose range 4–12 Gy led to a more compact structure of PVA/PEG copolymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with gamma dose has been determined using DTA. The PVA/PEG thermograms were characterized by the appearance of an endothermic peak due to melting of crystalline phase. In addition, structural property studies using X‐ray diffraction and infrared spectroscopy were performed on both nonirradiated and irradiated samples. Furthermore, the transmission of the PVA/PEG samples and any color changes were studied. The color intensity (E was greatly increased with increasing the gamma dose and was accompanied by a significant increase in the blue and green color components. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

渗透汽化分离DMF/水混合物的PVA-g-AAm膜的制备和表征

使用聚乙烯醇及丙烯酰胺这两种材料,合成了不同枝度的共聚物(PVA-g-AAm),并对两种渗透汽化复合膜(PVA-g-AAm)进行制备。黏均分子量是运用用黏度法测定的,而表征则分别由接触角,红外光谱(FT-IR)和热重(TGA)等方法进行测定。而DMF/水混合体系的渗透汽化分离主要是复合膜的运用,并对膜分离的影响因素进行分析。实验结果显示,分离性能最好的是接枝度为90%的PVA。而PVA的渗透量随着DMF质量分数的增加而减少,PVA的通量最小时是在0.25~0.65 kg/(m~2·h)之间,在0.2~而膜的分离因子达到最大时DMF质量分数为33%。而温度的增加可是渗透量增大,分离因子减小。