聚氯乙烯/邻苯二甲酸二烯丙酯聚合物加工性能和力学性能研究

采用转矩流变仪对实验室自制的聚氯乙烯/邻苯二甲酸二烯丙酯(PVC/DAP)聚合物的加工性能进行了研究,探讨了DAP含量对PVC加工性能的影响。结果表明,随着DAP含量的增加,PVC/DAP聚合物的塑化时间缩短,平衡扭矩、峰值扭矩均减小,平衡温度下降;拉伸强度和断裂伸长率均有所增加。     

硅烷交联聚氯乙烯的制备和性能

对由悬浮共聚合成的氯乙烯／乙烯基三乙氧基硅烷共聚树脂的水解交联行为和交联聚氯乙烯的性能进行了研究。结果发现，通过聚合过程添加pH调节剂可得到凝胶含量很低的氯乙烯／乙烯基三乙氧基硅烷共聚树脂；该类共聚树脂加工后有一定程度交联发生，凝胶含量随共聚树脂中乙烯基三乙氧基硅烷含量增加而增加；当加工样品在水中浸渍后凝胶含量又有较大幅度提高，说明水解交联的发生；交联后PVC高温力学性能和耐热变形性提高。     

硬质交联PVC泡沫塑料的制备

以聚氯乙烯(PVC)为基体,马来酸酐为接枝剂,异氰酸酯、三聚氰胺为交联剂,制备出性能优异的硬质交联PVC泡沫塑料;通过红外光谱、热失重和热机械分析及凝胶含量测定对硬质交联PVC泡沫塑料进行分析,证实交联反应发生在水煮工艺阶段,玻璃化转变温度在180℃左右;研究了马来酸酐用量对硬质交联PVC泡沫塑料凝胶含量的影响,马来酸酐的用量在塑化成型阶段对交联度的影响较小,硬质交联PVC泡沫塑料的凝胶含量随着马来酸酐用量的增加而增大;用光学显微镜对硬质交联PVC泡沫塑料的泡孔直径进行了测量。结果表明,硬质交联PVC泡沫塑料的泡孔直径分布较为均匀,密度为60 kg/m3的泡孔直径主要分布在100~130μm,密度为90 kg/m3的泡孔直径主要分布在70~80μm;测定了硬质交联PVC泡沫塑料的力学性能,结果显示,其具备同瑞士Airex C70产品相当的力学性能。     

高密度聚乙烯的交联过程和结晶行为研究

利用过氧化物交联剂对聚乙烯体系进行了交联,研究了不同交联温度下交联聚乙烯的交联过程和流变行为,以及不同交联度对交联聚乙烯交联密度、结晶度、晶体尺寸以及力学性能的影响。结果表明,随着交联温度的升高,交联聚乙烯的交联反应逐渐加快,凝胶含量由30%提高到60%,交联密度也逐渐增加,在180℃以上尤为明显。随着交联度的增加,体系的结晶度由70%逐渐下降到58%,晶体尺寸逐渐增加。体系的冲击强度随交联度的增加而增加,而弯曲模量略微下降;交联聚乙烯在高凝胶含量时具有优异的高温蠕变性能,热变形率降低了95%。     

PVC消光树脂的生产现状及技术

介绍了PVC消光树脂的发展现状、合成工艺、性能表征方法、凝胶含量的影响因素以及加工性能,总结了引发剂对聚合反应的影响及PVC消光制品消光性能的影响因素。     

PVC膜专用料力学性能影响因素的探究

采用转矩流变仪、扫描电子显微镜、差示扫描量热仪和傅立叶变换红外光谱仪研究了聚氯乙烯(PVC)在不同加工温度和转速下的流变性能、塑化行为和结晶性能,探究了塑化效果、微纳层叠器数量对PVC力学性能的影响和PVC专用料吹塑成膜后的力学性能。结果表明,随着加工温度升高、转速增加,塑化时间缩短、凝胶化度增加,塑化行为进行越充分,而平衡扭矩随着加工温度升高而减小,随转速提高而增大;PVC结晶度随加工温度提高而增大,随转速增加而下降。在加工温度为185℃下,随着转速的提高,试样的断裂伸长率不断增大,而纵向、横向拉伸强度先增大后减小,且在转速为40 r/min时均达到最大值,分别为24.8 MPa和23.3 MPa,;在转速为40 r/min下,随着加工温度的提高,试样的断裂伸长率不断增大,而纵向、横向拉伸强度均先增大后减小,且在加工温度为185℃时均达到最大值,分别为24.6 MPa和22.6 MPa。PVC片材的密度和纵向拉伸强度与微纳层叠器数量成正比;与未加微纳层叠器相比,经过6节微纳层叠器后吹塑成膜的轴向拉伸强度提高13.5%,轴向断裂伸长率提高12.4%,轴向直角撕裂强度相应提高34.7%。     

消光PVC树脂合成与加工成型的研究

研究了交联剂用量及加入方式、聚合温度对PVC树脂消光性能的影响,以及挤出温度对PVC制品消光性能的影响;对比了采用普通PVC树脂加消光剂生产的制品与采用消光PVC树脂生产的制品的消光性能。结果表明:①消光PVC树脂最佳的生产工艺为交联剂用量在0.3份左右,聚合过程中交联剂采用连续加入的方式,聚合温度应根据PVC制品凝胶含量的需求进行设定;②当挤出机各段温度分别为130、145、150、155℃,模头温度为165℃时,PVC制品的消光性能最好;③与采用加消光剂的方式相比,采用消光PVC树脂生产的制品消光性能更好。     

热可逆交联剂对PVC力学性能及热性能的影响

用一种热可逆交联剂与聚氯乙烯(PVC)树脂熔融共混,研究了交联剂用量和交联时间对交联PVC制品力学性能和热性能的影响,分析了交联产物的热可逆转化行为。结果表明:热可逆交联剂能有效提高PVC制品的力学性能和热稳定性,当交联剂用量为3份时,PVC制品的力学性能达到最大值,维卡软化温度提高了4℃;PVC制品的凝胶含量随交联剂用量的增多而增大;交联时间为20 min时,PVC有较高的力学性能和热性能,更为重要的是PVC交联后具有热可逆转化特性。     

消光PVC专用树脂的合成研究

本文通过氯乙烯/交联剂悬浮聚合合成了含有部分凝胶结构的消光PVC专用树脂，讨论了交联剂，聚合温度，分散剂及引发剂等对消光性能的影响。并初步分析了树脂的加工性能。     

改性纳米二氧化硅对PVC树脂性能的影响

研究了改性纳米二氧化硅(SiO_2)的用量对PVC树脂加工性能和消光性能的影响,并通过SEM-EDS考察了改性纳米SiO_2在PVC基体中的分散性能。结果表明:①随着SiO_2用量的增加,体系的加工性能变差;②当SiO_2用量≤1.5份时,体系的消光性能提高较少;③当SiO_2用量≥2份时,体系的消光性能与市售凝胶质量分数25%的消光型PVC-SG5树脂的消光性能差不多,但前者的加工性能优于后者;④SEM-EDS分析结果表明,改性过的纳米SiO_2与PVC基体的相容性较好,能均匀分散在基体树脂中。     

Structure–property relationships of lightly chemical crosslinked poly(vinyl chloride) thermoplastic elastomer

Chemical crosslinked poly(vinyl chloride) (C‐PVC) was synthesized by vinyl chloride suspension polymerization in the presence of diallyl phthalate (DAP) and plasticized to prepare poly(vinyl chloride) (PVC) thermoplastic elastomer (TPE) materials. The chemical crosslinking and physical crosslinking structure in chemical crosslinked PVC‐TPE were investigated. It showed that the gel fraction and the crosslinking density of gel increased as the feed concentration of DAP increased. C‐PVC prepared by VC/DAP copolymerization was lightly crosslinked as compared with irradiation crosslinked PVC. Physical entanglements would greatly influence the crosslinking density of gel when the gel fraction was high. Chemical crosslinking had little influence on the recrystallization behavior of PVC. A structure model of chemical crosslinked PVC‐TPE was proposed, in which chemical networks acted with physical networks cooperatively. It also showed that chemical crosslinking and physical crosslinking influenced the processability and mechanical properties of chemical crosslinked PVC‐TPE cooperatively. Although the processability of PVC‐TPE deteriorated with chemical crosslinking, the dimension stability and elasticity of PVC‐TPE were improved as the permanent chemical networks were introduced. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 868–874, 2000     

橡胶籽油基复合型环保增塑剂用于PVC的研究

将自制的橡胶籽油基环氧脂肪酸甲酯（EFAME）与对苯二甲酸二辛酯（DOTP）混合后,与聚氯乙烯（PVC）共混成型,考查EFAME在软质PVC中的增塑性能及其对DOTP的替代效果。利用拉力试验机、差示扫描量热仪、动态热力学分析仪及热老化烘箱对塑化体系的力学性能、加工性能、耐热性及耐久性进行分析。结果表明,复合型增塑剂可有效改善PVC制品的柔韧性、耐磨性、热性能及加工流变性;EFAME用量为20份时,PVC制品的玻璃化转变温度由0.32 ℃降低至-4.63 ℃,质量损失10 % 和50 %时的温度得到提高,热老化整体变色时间提高了4倍。     

Self‐crosslinking and cocrosslinking with nitrile rubber of poly(vinyl chloride) with pendent N,N‐diethyldithiocarbamate group

In order to realize the self‐crosslinking and cocrosslinking of poly(vinyl chloride) (PVC) with nitrile‐butadiene rubber (NBR), PVC with pendent N,N‐diethyldithiocarbamate groups (PVC‐SR) was prepared from the reaction of PVC with sodium SR in butanone. The PVC‐SR was self‐crosslinked and the PVC‐SR/NBR blend was cocrosslinked under heating at 170°C. The effect of the degree of functionality of PVC‐SR on the torque, gel content, glass‐transition temperature, and tensile properties was investigated. The results showed that the crosslinking reaction did not occur for PVC, NBR, or the PVC/NBR blend. Introducing the SR groups into PVC caused the crosslinking reaction to occur and the high gel contents of the crosslinked samples were obtained in 15 min. The degree of crosslinking increased with the degree of functionality of PVC‐SR. The mechanism of the crosslinking reaction was discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 634–638, 2001     

双马来酰胺酸交联PVC的交联行为研究(Ⅰ)

用哈克流变仪来研究以双马来酰胺酸作为交联剂、DCP(过氧化二异丙苯)为引发剂、DOP(邻苯二甲酸二辛酯)为增塑剂的交联PVC的交联特性。研究表明:PVC交联反应速率随增塑剂用量的增加而减慢,PVC的凝胶率也变低;交联剂用量越多,凝胶率越大;提高反应温度或增加反应时间可提高凝胶率。     

Irradiation Crosslinking of PVC/ENR Blend: A Comparative Study with the Respective Homopolymers

Electron beam initiated crosslinking on a 50/50 poly(vinyl chloride)/epoxidized natural rubber blend was studied in the absence and presence of 3 phr trimethylolpropane triacrylate (TMPTA). Comparative studies were made on PVC and ENR homopolymers. The samples were irradiated by using a 3.0 MeV electron beam machine at doses ranging from 20 to 200 kGy in air and room temperature. The changes in tensile strength, gel fraction and tan δ curves of the samples were investigated. The enhancement in tensile strength, gel fraction, glass transition temperature together with a concomitant decline tan δ peak revealed that under the irradiation conditions employed, the PVC/ENR blend crosslinked by electron beam irradiation. Addition of 3 phr TMPTA found to be effective in increasing the degree of crosslinking. Similar observations were also noted for the homopolymers PVC and ENR, implying that both PVC and ENR in the blend undergo crosslinking to a certain extent.     

The structure and dynamic properties of nitrile–butadiene rubber/poly(vinyl chloride)/hindered phenol crosslinked composites

In this article, a new nitrile–butadiene rubber (NBR) crosslinked composites containing poly(viny chloride) (PVC) and hindered phenol (AO-80 and AO-60) was successfully prepared by melt-blending procedure. Microstruture and dynamic mechanical properties of the composites were investigated using SEM, DSC, XRD, and DMTA. Most of hindered phenol was dissolved in the NBR/PVC matrix and formed a much fine dispersion. The results of DSC and DMTA showed that strong intermolecular interaction was formed between the hindered phenol and NBR/PVC matrix. The NBR/PVC/AO-80 crosslinked composites showed only one transition with higher glass transition temperature and higher tan δ value than the neat matrix, whereas for the NBR/PVC/AO-60 crosslinked composites, a new transition appeared above the glass transition temperature of matrix, which was associated with the intermolecular interaction between AO-60 and PVC component of the matrix. Both AO-80 and AO-60 in the crosslinked composites existed in amorphous form. Furthermore, the chemical crosslinking of composites resulted in better properties of the materials, e.g., considerable tensile strength and applied elastic reversion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Crosslinking of poly(vinyl chloride) with bismaleic compound. II. Rheological behavior and mechanical properties of crosslinked PVC

In this study the rheological behavior of crosslinking PVC was studied. We carefully probed the effects of styrene and initiators on crosslink course and further verified PVC's crosslink mechanism suggested previously. St as auxiliary crosslinker was very important for PVC crosslink, no matter whether at lower temperature or at higher temperature, in the absence of initiator or in the presence of initiator. With higher decay temperature cumvl hydroperoxide (CHP) was a very appropriate initiator for PVC crosslinking. By controlling technological conditions, the crosslinked PVC with different cross density was obtained. We found that PVC with THF-insoluble fraction of about 7% had the best tenacity and maximum breaking energy. The tensile strength would increase as the gel-fraction content increased. By citing T. Kurauchi's ROF toughening theory, we satisfactorily explained the good ductility of crosslinked PVC with low cross density and the high fragility of over-crosslinked PVC. Because the motion of segments is hindered in thoroughly crosslinked PVC, its glass transition was so weak that we hardly found out T_g.     

A solid-state 13C nuclear magnetic resonance study of cured,unsaturated polyester resins

The styrene sequence distributions and amount of reacted fumarate units in cured, unsaturated polyester resins were studied by solid-state ¹³C nuclear magnetic resonance. Increasing the styrene content and molar ratio of styrene to the double bonds in the polyester chain increased the amount of diad and n-ad sequences and decreased the amount of monad sequences. At the same time, the amount of reacted fumarate units increased. The glass transition temperature was almost constant for resins with the same composition but different styrene contents. Changing the composition affected the glass transition temperature, which could not be detected for highly crosslinked resins. The mechanical properties were improved with increasing styrene content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 563–571, 1999     

Synthesis and characterization of biodegradable crosslinked polymers from 5‐hydroxylevulinic acid and α,ω‐diols

Novel biodegradable chemically crosslinked polymers, poly(5‐hydroxylevulinic acid‐co‐α,ω‐diol)s (PHLA‐diols), were synthesized from 5‐hydroxylevulinic acid and α,ω‐diols and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The gel content, swelling ratio, tensile properties, and hydrolytic degradation behaviors were also measured and assessed. The glass‐transition temperature of the PHLA‐diols could be adjusted within a wide range (?50 to 30°C) by the type and feed ratio of the diol. Because of the low glass‐transition temperature and crosslink structure, they exhibited certain elastic properties. The tensile modulus, strength, and elongation at break measured at 37°C were 1.4–6.3 MPa, 0.8–1.6 MPa, and 10–25%, respectively. These polymers could be hydrolytically degraded. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010