PVA—CS共混体系相容性的研究

利用ＤＳＣ等方法，研究了ＰＶＡ－ＣＳ二元共混体系的相容性。结果表明，ＰＶＡ与ＣＳ之间存在一定的相互作用为部分相容体系，以Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ的高分子溶液理论为基础，通过Ｗｏｏｄ或Ｆｏｘ方程，计算出不同共混出ＰＶＡ－ＣＳ共混体系两相中二组分的表面质量分率，进而计算出体系的聚合物－聚合物Ｆｌｏｙ－Ｈｕｇｇｉｎｓ相互作用参数，ｘ１２或ｇ１２，对ＰＶＡ－ＣＳ共混体系的相容性进行了验证。     

新型渗透汽化透水膜的研制（II）：膜的结构和性能

确定聚合物共混的相容性最常用的方法是通过测定共混物的玻璃化转变温度（Ｔｇ），本文利用ＤＳＣ－７（Ｅｐｓｏｎ）测定了不同共混比的ＰＶＡ，ＣＳ共混物的玻璃化转变温度，结果表明ＰＶＡ，ＣＳ之间有良好的相容性。本文利用扫描电子显微镜（ＳＥＭ），红外光谱（ＩＲ）和Ｘ－射线衍射（ＸＲＤ）等现代分析仪器，对研制的多元酸交联的ＰＶＡ－ＣＳ／ＰＳＦ膜结构进行了观察测试，探讨了膜结构与性之间的关系。     

聚醚型多嵌段聚氨酯与氯化聚氯乙烯共混物的相容性研究

用ＤＳＣ及ＦＴＩＲ方法研究了聚四亚甲基醚型多嵌段聚氨酯（ＳＰＵ）与氯化聚氯乙烯（ＣＰＶＣ）共混物的相容性。结果表明,共混物具有两个分立的Ｔｇ,属不相容体系。ＦＴＩＲ结果表明随共混物中ＣＰＶＣ含量的增加,其ＳＰＵ组分的氢键键合的Ｃ＝Ｏ、Ｎ－Ｈ吸收峰所占的分数明显减少,ＣＰＶＣ与ＳＰＵ分子间存在较强的相互作用。多嵌段聚氨酯硬段含量的增加,加强了ＳＰＵ分子间的相互作用,同时也减小了共混物两组分的相容性。     

CA／PAN共混体系相容性的研究

应用ＤＳＣ、ＳＥＭ、ＦＴ－ＩＲ等方法，研究了ＣＡ－ＰＡＮ、ＣＡ－ＰＡＮ－Ｔｏ二元和三元混溶液的相容性。结果表明，ＣＡ和ＰＡＮ存在一定的相互作用，有部分相容性。改变共混比例，共混膜具有不同微相区的两相结构，Ｔｏ有助于提高两组分的相容性。     

聚醚砜四元制膜液体系的相图计算

以Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ理论为基础，对ＰＥＳ－ＰＧ－ＮＭＰ＿Ｈ２Ｏ＿）聚醚砜丙二醇－Ｎ－甲基－２－哟咯烷酮水）四元制液体系的相图进行了计算，利用三元相图考察Ｈ２Ｏ和ＰＧ对液－液相分离的影响，在三元的理论的基础上提出了低分子量添加剂的卤元改性Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ理论，并提出了一种获得四元相图的方法，利用四元相图能较争地描述四元体系，利用改性的四元理论，能了地理解该种体系的液－液相分离行为。     

PVC/PA1010/SBS-g-MAH共混体系研究

制备了ＳＢＳ－ｇ－ＭＡＨ接枝聚合物,并对其进行了表征,以ＳＢＳ－ｇ－ＭＡＨ作为ＰＶＣ／ＰＡ１０１０共混体系的增剂,对不同配比的ＰＶＣ／ＰＡ１０１０／ＳＢＳ－ｇ－ＭＡＨ共混体系的物理力学性能,流变性及差热性等进行了研究,结果表明,ＳＢＳ－ｇ－ＭＡＨ接枝聚合物对ＰＶＣ／ＰＡ１０１０共混体系起到了明显的增容作用,得到了缺口冲击强度及拉伸强度均较高的ＰＶＣ／ＰＡ１０１０／ＳＢＳ－ｇ－ＭＡＨ共混物。     

聚氯乙烯／聚丙撑碳酸酯共混相容性研究

分别用溶液法和熔融法制得聚氯乙烯（ＰＶＣ）与聚丙碳酸酯（ＰＰＣ）共混试样，用ＤＳＣ证明ＰＶＣ／ＰＰＣ不相容，但它们不相容的程度受分子量、共混比例及共混方法等因素的影响，并根据玻璃化转变温度计算出溶液２共混试样ＰＰＣ富相中ＰＶＣ的质量百分含量。用ＤＭＡ说明了ＮＢＲ／ＰＰＣ对ＰＶＣ／ＰＰＣ共混体系具有良好的增容作用，共混体系中ＰＰＣ的用量对共混体系相容性有一定程度的影响，加入适量的ＰＰＣ可提高共混试样     

HPB－b－PMMA增容PVC／PE共混物球晶和结晶行为研究

以小角激光散射（ＳＡＬＳ）和广角Ｘ光衍射（ＷＡＸＤ）技术，测定了氢化聚丁二烯－聚甲基丙烯酸甲基嵌段共聚物（ＨＰＢ－ｂ－ＰＭＭＡ）增容的聚氯乙烯（ＰＶＣ）和聚乙烯（ＰＥ）共混物的球晶形态和结晶度。从该共混物中ＰＥ的结晶状况得出，增容剂ＨＰＢ－ｂ－ＰＭＭＡｄ在降低ＰＥ结晶能力、增加ＰＥ／ＰＶＣ界面粘合并形成ＰＶＣ和ＰＥ相间的部分相容性有着重要的作用。     

PVC／MBS共混物的相容性研究

根据ＭＢＳ核壳结构的特征，分析了与ＰＶＣ进行共混时两组分溶解度参数与相容性的关系，采用差示扫描量热法（ＤＳＣ），考察共混体系中玻璃化转变温度的变化，表明ＰＶＣ／ＭＢＳ体系的相界面具有较好相和粘合作用。用红外光谱法测定，发现了共混体系中ＰＶＣ－ＭＢＳ间氢键的存在，从而提高了组分的相容性。通过ＰＶＣ－ＭＢＳ片材的热粘合样品的切强度试验，也可观察它们界面的相容程度。     

P(MMA-BA-MAA)／P(MMA-BA-VP)共聚物复合体系的氢键相互作用

通过乳液共聚合分别合成了两种具有互补结构的共聚物乳液：聚（甲基丙烯酸甲酯－丙烯酸丁酯－甲基丙烯酸聚Ｐ（ＭＭＡ－ＢＡ－ＭＭＡ）和聚（甲基丙烯酸甲酯－丙烯酸丁酯－乙烯基吡咯烷酮）Ｐ（ＭＭＡ－ＢＡ－ＶＰ）。通过^1H-NMR测定,研究了共聚物组成与单体投料组成的关系;通过ＦＲ－ＩＲ、ＤＳＣ、表 及力学性能测试,研究了Ｐ（ＭＭＡ－ＢＡ－ＭＭＡ）／Ｐ（ＭＭＡ－ＢＡ－ＶＰ）共聚物复合体系氢键相互作用及其对聚合物性能的影响,结果表明Ｐ（ＭＭＡ－ＢＡ－ＭＭＡ）／Ｐ（ＭＭＡ－ＢＡ－ＶＰ）共聚物复合体系存在氢键相互作用,氢键相互作用导致复合体系表面降低、拉伸强度提高。     

聚乙二醇／聚乙烯醇共混物的相变特性与结晶

通过溶液共混法制备了系列PEG4000／PVA共混物，并采用DSC、WAXD、FT-IR等手段对共混体系的相变特性及结晶进行了探讨。结果表明：共混体系具有可逆的固-固相转变特性。共混物的熔点（Tm）基本保持不变，而结晶峰值温度（Tc）与PEG／PVA质量百分含量有关。其相变焓是随着PEG含量的增加而逐渐增加。聚乙烯醇的存在对共混体系中PEG的结晶和熔融过程均有所影响，但共混体系与纯PEG4000具有相同的衍射线、衍射角和面间距，且并未发现新的衍射峰出现。共混体系中x射线衍射峰的半峰宽度大于纯PEG的半峰宽度，说明共混过程使PEG结晶粒子变小。     

聚氧化乙烯与聚乙烯醇共混体系的研究

采用水溶液共混法制备共混物，研究了聚氧化乙烯与聚乙烯醇共混体系的相容性及共混体系中各组分的结晶性。实验结果表明，ＰＥＯ／ＰＶＡ共混物为不相容共混体系。ＰＶＡ分子间易于形成氢键是此共混体系不相容的主要原因。ＰＥＯ／ＰＶＡ共混体系为相分离结构，ＰＥＯ及ＰＶＡ皆可在各自的相区内形成结晶。体系中ＰＶＡ的存在不影响ＰＥＯ的结晶能力，共混体系在组成为５０／５０左右其力学性能有急剧变化，提示在此时发生了相倒转。     

PVA-PEG/SiO_2-TiO_2杂化纤维的制备与表征

以聚乙烯醇(PVA)与聚乙二醇(PEG)共混,并以正硅酸乙(酯TEOS)和钛酸四丁酯(TBT)为无机前驱体,采用溶胶-凝胶法制备了不同(SiO_2-TiO_2)含量的PVA-PEG/SiO_2-TiO_2杂化溶胶,陈化后用提拉法制得杂化纤维.研究了杂化溶胶的可纺性,并使用IR、光学显微镜、UV-Vis和TG对杂化纤维的结构与性能进行了研究.结果表明:随硅钛摩尔比的增加或随有机相中PEG/PVA质量比的增加,溶胶的可纺性变好;有机相与无机相之间通过化学键连接;纤维直径为50μm左右;TiO_2的引入增加了其抗紫外性,杂化纤维的耐热性优于纯PVA-PEG.     

PVA／P（VA—VP）共混物的动态力学性能

用粘弹谱法(DVE)研究了醋酸乙烯酯和乙烯基吡咯烷酮共聚物的水解物P(VA-VP)和聚乙烯醇(PVA)共混体系的动态力学行为。共混物的阻尼松弛谱(tgδ)表明了共混体系的相容性随着组成比的不同而明显不同,一些组成比的共混物不仅存在晶相和非晶相的聚态结构,而且在非晶相态里随着组成比的不同还存在着微观结构不均匀性和相容性的差异。组成比(W_(PVA))为40～60％的共混物其复合模量和tgδ谱表明共混物中PVA的晶相是均匀分散在共容的非晶介质中,因而在室温至约80℃范围内能形成强度比纯PVA更好的有实用意义的功能PVA合金。 选择两种不同组成比的共混物通过改变升温速率和作用力频率的试验表明,随着升温速率的下降,非晶部分的相容性增大而晶相部分的结晶度增加;作用力频率的下降导致结晶度提高和T_8真升高。     

PVA-壳聚糖/有机累托石复合膜的结构与性能

目的将聚乙烯醇(PVA)引入壳聚糖(CS)/有机累托石(OREC)复合体系制备插层效果、力学性能、抗紫外老化及阻隔性能良好的插层纳米复合膜。方法利用溶液流延法制备PVA-CS/OREC系列复合膜,以XRD及SEM研究复合膜的插层结构及OREC在基体中的分散性,研究复合膜的力学性能、抗紫外辐射性及水蒸气透过性。结果 OREC及PVA添加量较少时可与CS形成良好的插层结构。当OREC质量分数为2%,PVA质量分数为10%时的复合膜(标记为PVA10-CS/OREC2)插层结构最好,OREC在CS及PVA基体中分散性最好,与OREC质量分数为2%且不含PVA的复合膜(标记为CS/OREC2)相比,拉伸强度提高42.2%,断裂伸长率提高30%,水蒸气透过量降低10.2%,复合膜经紫外辐射后拉伸强度保持率、断裂伸长保持率仍达82.5%及68.2%。结论 PVA10-CS/OREC2膜可作为医用膜和药品、食品等的包装材料。     

Thermomechanical properties of poly(vinyl alcohol) plasticized with varying ratios of sorbitol

The objective of this work is to study the thermal and mechanical properties of films based on blends of poly(vinyl alcohol) (PVA) with different weight percent of sorbitol. Solid-state PVA/sorbitol polymer membranes were prepared by a solution casting method. The characteristic properties of these polymer membranes were examined by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), nanoindentation methods and by Fourier Transform Infrared (FTIR) spectroscopy. It was found that the thermal properties (glass transition, T_g, melting point, T_m and decomposition temperature, T_d) for PVA blends showed a decrease proportional to the sorbitol concentrations. The hardness and elastic modulus obtained from nanoindentation test were also found to decrease with increase in plasticizer concentration. FTIR confirmed the reduction in hydrogen bonding between PVA chains in favour of formation new bonding between the plasticizer and the PVA chains.     

Influence of compositions of modified blends of polyamide/poly(vinyl alcohol) on the methanol/gasoline fuel barrier properties of polyethylene/modifiedblends of polyamide/poly(vinylalcohol) bottles

Polyamide (PA), poly(vinyl alcohol) (PVA) and the blends of PA and PVA were modified by a compatibilizer (CP) to make modified polyamide (MPA), modified PVA (MPVA) and modified PA/PVA (MPAPVA) blends through reactive extrusion. The MPVA and MPA hot-pressed sheets exhibit the best and worst methanol/gasoline fuel permeation resistance among these modified resins, which show much better methanol/gasoline fuel permeation resistance than pure PE resin. It is worth noting that the methanol/gasoline fuel permeation resistance of MPAPVA sheets improves consistently with their PVA contents. Similarly, after blending these barrier resins with PE, the methanol/gasoline fuel permeation resistance of the blended bottles improves to become significantly better than that of pure PE bottles. Further investigations found that the hydrocarbon components with 5 to 10 main-chain carbon atoms present in methanol/gasoline fuels were successfully blocked during the permeation tests. However, the order of barrier improvement of PE/MPA, PE/MPAPVA and PE/MPVA bottles does not completely correspond to the order of the barrier improvement of the base barrier resins before blending and blow-molding with PE. For instance, the PE/MPVA and PE/MPAPVA bottle series with a PVA/PA weight ratio of 4 : 1 exhibit poorer methanol/gasoline fuel permeation resistance than all the other PE/MPAPVA bottles, although the base MPVA and MPAPVA with a 4 : 1 PVA/PA weight ratio are associated with better permeation resistance than the other MPAPVA resins prepared in this study. These interesting phenomena were investigated in terms of the melt shear viscosities, chemical structure and morphology of the barrier resins present in their corresponding bottles.     

Electrospun single-walled carbon nanotube/polyvinyl alcohol composite nanofibers: structure-property relationships

Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde.     

Strain hardening behavior of lightweight hybrid polyvinyl alcohol (PVA) fiber reinforced cement composites

Experimental results on the strain hardening and multiple cracking behaviors of polyvinyl alcohol (PVA) fiber reinforced cementitious composites under bending are reported in this paper. Different hybrid combinations of PVA fibers with different lengths and volume fractions are considered to reinforce the mortar matrix. Among different hybrid combinations, the composite containing 2% thicker PVA fibers of 12 mm length and 1% thinner PVA fibers of 6 mm length and the composite containing 2% thicker PVA fibers of 24 mm length and 1% thinner PVA fibers of 6 mm length showed the best performance in terms of highest ultimate load, largest CMOD (crack mouth opening displacement) at peak load and multiple cracking behavior. The effects of four types of light weight sands on the strain hardening and multiple cracking behavior of hybrid fiber composites are also evaluated in this study. It has been observed that the ultimate load and CMOD at peak load for all light weight hybrid fiber composites are almost the same irrespective of volume fractions of light weight sand. The composites containing finer light weight sands exhibited higher ultimate load than those containing coarser light weight sands. It is also observed that the hybrid fiber composite containing normal silica sand exhibited higher ultimate load than the composites with light weight sands.     

热塑性聚氨酯/聚乙烯醇共混材料制备及性能

通过溶液共混的办法,制备了热塑性聚氨酯(TPU)/聚乙烯醇(PVA)共混材料。通过FI-IR、DMTA初步考查了两相的相互作用;同时对共混材料的水溶胀性能进行了表征。结果表明, TPU/PVA两相存在氢键作用,具有一定的相容性;共混材料吸水率随着PVA的加入而逐渐增大,两相配比为7:3时,共混材料力学性能最佳。