全生物降解PBS的扩链改性研究

采用新型扩链剂2,2′-双(2-噁唑啉)(BOZ)对聚丁二酸丁二醇酯(PBS)进行扩链,研究了BOZ加入量、稳定剂加入量、时间、温度对扩链反应的影响。结果表明,选择最佳条件,扩链后的PBS的相对分子质量较未扩链PBS的相对分子质量大为增加,而且扩链PBS相对分子质量分布与未扩链PBS基本一致,说明PBS扩链后的线性度与起始PBS相同,没有支化或交联反应发生。     

扩链反应制备聚乳酸-co-聚己二酸丁二醇酯多嵌段共聚物

为了改善一步法生产的聚乳酸(PLA)均聚物分子量低、材料脆性大的问题.文章使用二苯基甲烷二异氰酸酯(MDI)作为扩链剂,在催化剂存在的条件下,通过熔融扩链反应制备聚乳酸-聚己二酸丁二醇酯多嵌段共聚物(PLA-b-PBA).并进一步研究了反应温度、预聚体分子量、扩链剂用量对扩链产物的结构、分子量的影响.用凝胶渗透色谱GPC、红外光谱IR、核磁共振分析1H NMR、13C NMR对预聚体及扩链产物进行了分析表征,结果表明通过扩链反应,聚乳酸的分子链中引入了新的嵌段,分子量有大幅度提高.     

不同扩链剂对PBS性能的影响

通过熔融溶液相结合的方法合成聚丁二酸丁二醇酯(PBS)预聚物。用异佛尔酮二异氰酸酯(IPDI)、六亚甲基-1,6-二异氰酸酯(HDI)和丁二酰氯(SUC)对PBS预聚体进行扩链改性。采用熔点仪测定PBS的熔点;采用傅里叶变换红外光谱仪对PBS的结构进行了表征;采用凝胶渗透色谱仪、热重仪和万能实验机测定了PBS的摩尔质量及其分布、热稳定性和力学性能;测定失重率,考察不同扩链剂对PBS降解性能的影响。结果表明:PBS扩链后摩尔质量均有显著提高,摩尔质量分布均小于扩链前;且断裂伸长率等力学性能和热分解温度等热性能也都有明显改善。但用不同扩链剂扩链后,PBS降解性能有较大区别。     

聚己二酸丁二醇-co-聚对苯二甲酸丁二醇酯扩链改性研究

为了降低聚己二酸丁二醇-co-聚对苯二甲酸丁二醇酯(PBAT)的熔融指数,在双螺杆中,利用多元环氧扩链剂(ADR)对PBAT进行了扩链反应.基于正交实验对ADR扩链PBAT反应进行了研究,确定了影响反应的主要因素,并对扩链后的树脂进行了流变以及常规性能研究.结果 表明,扩链剂浓度对扩链反应速率影响最大,反应温度次之.A...     

可降解塑料PBS的扩链研究进展

概述了可降解塑料PBS(聚丁二酸丁二醇酯)的两种扩链方法.按照扩链刺与PBS端基的反应特点,将PBS用扩链剂分为适于端羟基的扩链剂和适于端羧基的扩链剂两种.介绍各类扩链剂的研究进展及优缺点,同时概述各自的反应机理,提出进一步开发PBS用扩链剂的发展方向.     

聚酯类生物基聚合物的扩链改性

以丙二醇、丁二醇、癸二酸、丁二酸及衣康酸为原料合成了端羟基与端羧基并存的聚酯类生物基预聚物,以亚磷酸三苯酯(TPP)为扩链剂,研究了扩链温度、TPP添加量及数均分子量不同的预聚物等对扩链反应的影响。结果表明,在扩链温度为180℃、预聚体数均分子量为1.0×104左右的条件下,加入质量分数为15%的TPP,经扩链反应后,产物的数均分子量可达到4.8×104。红外光谱分析证实了扩链反应的发生;差示扫描量热分析结果显示扩链后产物的玻璃化转变温度有所上升,熔点有所下降;热重分析表明扩链后产物的热稳定性有所提高。     

环氧树脂扩链PBT研究

选取环氧树脂为扩链剂,以聚对苯二甲酸丁二酯(PBT)熔体在Haake转矩流变仪中的相对转矩变化表征扩链效果,研究了环氧树脂扩链PBT过程中,扩链剂的选择、扩链剂用量、反应条件、扩链剂联用、催化剂等对扩链反应的影响.通过实验发现不同类型环氧树脂的扩链效果差异很大,缩水甘油酯类具有最好的扩链效果;随着扩链剂加入量的增加,扩链效果先增加后降低,存在一个最佳的扩链剂加入量;提高反应温度和剪切速率均可加快扩链反应速率;利用邻苯二甲酸酐和环氧类扩链剂联用可以提高扩链反应速率和扩链效果;选取三氧化二锑作为催化剂不仅提高了扩链反应的速率,同时也提高了扩链效果.     

聚丁二酸丁二醇酯扩链及其发泡行为的研究

以聚丁二酸丁二醇酯(PBS)为基体,ADR-4370S为扩链剂,通过熔融共混法制备了扩链PBS;通过扭矩曲线、凝胶含量测试、差示扫描量热仪测试、旋转流变仪测试,研究了PBS扩链前后分子结构、热性能、流变性能的变化;利用超临界二氧化碳(CO_2)作为物理发泡剂,通过间歇式釜压发泡成型制得不同类型的PBS泡沫样品,研究了扩链剂添加量和发泡温度对PBS发泡行为的影响。结果表明,随着扩链剂的加入,PBS的分子链由线形转变为长支化结构,甚至形成了部分交联网状结构;PBS的结晶温度和黏弹性逐渐提高;当扩链剂添加量为1.5份(质量份,下同),发泡温度为105℃时,PBS的发泡倍率取得最大值。     

环氧基扩链剂对聚丁二酸丁二醇酯流变和结晶行为的影响

通过熔融共混法将环氧基扩链剂和聚丁二酸丁二醇酯(PBS)进行混合扩链.通过旋转流变仪、凝胶渗透色谱、差示扫描量热仪、偏光显微镜等对共混物进行了测试表征.研究发现:PBS经过扩链以后,复数黏度、储能模量和损耗因子得到明显改善,重均分子量和结晶温度显著升高,结晶速率加快,球晶尺寸变小且分布更加均匀,有利于提高PBS的力学和热学性能.另外,扩链后的PBS凝胶含量维持在1％以下.     

扩链聚对苯二甲酸丁二醇-co-聚己二酸丁二醇酯的合成及表征

采用1,4-丁二醇,对苯二甲酸二甲酯,己二酸合成了聚对苯二甲酸丁二醇-co-聚己二酸丁二醇酯(PBAT)。采用六亚甲基二异氰酸酯作为扩链剂合成了高分子质量的PBAT。研究了扩链反应时间,扩链剂用量对特性黏度的影响;反应温度,扩链剂用量,扩链反应时间对PBAT分子质量、端羧基值的影响。采用核磁共振及红外光谱对聚合物的结构进行了表征。研究结果表明六亚甲基二异氰酸酯可以显著提高PBAT的分子质量,扩链以后力学性能有明显的提高。     

核壳乳液聚合法制备聚丙烯酸酯-聚氨酯复合乳液

以聚四氢呋喃二醇(PTMG-1000)和异佛尔酮二异氰酸酯(IPDI)为基本原料,二羟甲基丙酸(DMPA)作为亲水扩链剂,甲基丙烯酸-β-羟乙酯(HEMA)作为偶联剂与甲基丙烯酸甲酯(MMA)反应,采用核壳乳液共聚法,制备了聚丙烯酸酯-聚氨酯复合乳液(WPUA);通过红外光谱、透射电镜对WPUA乳液粒子的结构进行观察,探讨了DMPA用量、聚氨酯预聚体R值、聚氨酯(PU)链段与聚丙烯酸酯(PA)链段质量比等因素对乳液外观、粘度、稳定性等性能的影响;结果表明,当DM-PA用量为6份,R值为2.5,PU链段与PA链段质量比为70∶30时,所得WPUA表观性能较为优异。     

多官能度扩链剂对水性光敏聚氨酯丙烯酸酯性能的影响

用IPDI、DMPA、PMTG（1000）、HEMA分别合成非扩链型和扩链型光敏聚氨酯丙烯酸酯（PUA）水分散液。通过红外光谱（FTIR）和动态热力学分析测试仪（DMA）对非扩链型与扩链型聚氨酯丙烯酸酯的结构和热力学性能进行了表征比较,同时从黏度、光固化速率、耐溶剂性、附着力、硬度和吸水性等方面对两种PUA乳液（涂膜）性能做了比较。研究结果表明：加入扩链剂丙三醇合成的聚氨酯丙烯酸酯树脂不仅涂膜的硬度大大地增强,而且亲水性、光固化速度和玻璃化转变温度（从-54．02℃提高到-37．78℃）也明显提高。     

室温自交联型阳离子水性聚氨酯的合成与表征

通过自乳化法,分别以3-氨基丙基三乙氧基硅烷与N-甲基二乙醇胺(MDEA)为封闭剂与亲水扩链剂,自制N-(1,1-二甲基-2-乙酰基)乙基]-β-二羟乙氨基丙酰胺(DDP),异佛尔酮二异氰酸酯、聚己内酯二醇、双酚A、ADH为基本原料制备出室温自交联型阳离子聚氨酯纳米水分散液(CBPU)。采用傅里叶变换红外光谱(FT-IR)、动态激光光散射(DLS)、透射电镜(TEM)对CBPU分子结构、乳液粒径与分布及乳胶粒形态进行了研究,研究了封闭率对涂膜表面水接触角及力学性能的影响。结果表明,产物分子结构中出现了叔胺基、Si—O—Si和氨基甲酸酯结构;乳液粒径随封闭率的增加而增加;乳胶粒粒径均一,呈规则的球形结构;增加CBPU封闭率,能提高涂膜的耐水性及力学性能。当CBPU封闭率为15%时,乳液粒径、涂膜水接触角及拉伸强度分别为80.86 nm、83°及23.4 MPa。     

Radiation crosslinking of poly(butylene succinate) in the presence of low concentrations of trimethallyl isocyanurate and its properties

Poly(butylene succinate) (PBS) with different molecular weights was irradiated using an electron beam (EB) in the presence of polyfunctional monomers at ambient temperature. Five polyfunctional monomers were used in this work. The highest amount of gel fraction was achieved when PBS was blended with trimethallyl isocyanurate (TMAIC). The amount of TMAIC introduced strongly influenced the amount of resulting gel. It was determined that the crosslinked PBS sample containing 1% TMAIC had a higher glass‐transition temperature than did the original PBS. It was also observed that the presence of crosslinking bonds in the irradiated PBS greatly improved its heat stability and diminished its ability to biodegradate. Accordingly, it can be concluded that crosslinked PBS in the presence of TMAIC significantly improved its heat resistant properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2238–2246, 2003     

Synthesis of aliphatic polyesters by a chain‐extending reaction with octamethylcyclotetrasilazane and hexaphenylcyclotrisilazane as chain extenders

Aliphatic HO-terminated polyesters such as poly(diethylene glycol adipate) (PDEGA), poly(ethylene adipate) (PEA), and poly(butylene succinate) (PBS) with molecular weight from 1247 to 1948 were synthesized through condensation polymerization from adipic acid or butanedioic acid with excess diethylene glycol, ethylene glycol, or butylene glycol. From the HO-terminated polyesters, polyesters with high molecular weight were synthesized by a chain-extending reaction with octamethylcyclotetrasilazane (OMCT) or hexaphenylcyclotrisilazane (HPCT) as chain-extenders. Gel permeation chromatography (GPC) characterization shows that the M_n of chain-extended PDEGA is from 12,644 to 32,870, M_w is from 22,786 to 70,048; M_n of chain-extended PEA is 11,368, M_w is 19,877; and the M_n of chain-extended PBS is from 9823 to 39,873, M_w is from 18,823 to 137,192. The chain-extended polyesters were also characterized by ¹H-NMR spectrum, IR spectra, and DSC spectra. The multiple peaks at 7.37 and 7.67 ppm in the ¹H-NMR spectrum of chain-extended PDEGA and peaks at 3051.1 and 1593.4 cm⁻¹ in the IR spectrum of the chain-extended PBS show the evidence of the  SiPh₂ structure in the polyesters obtained from the chain-extending reaction. DSC study shows that the bulky  SiPh₂ units introduced by the chain-extending reaction lower the regularity of the polyester chains, so the melting point of the chain-extended PBS and PEA decreases compared to that of the original HO-terminated PBS and PEA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3333–3337, 2004     

Polymerization of aqueous lactic acid to prepare high molecular weight poly(lactic acid) by chain-extending with hexamethylene diisocyanate

In order to synthesize the high molecular weight poly(lactic acid) [PLA], Hexamethylene diisocyanate [HDI] was used as a chain extender connecting the terminal group of polymers. Poly(lactic acid) of high molecular weight, 76000 (M_W) and 33000 (M_n), was obtained by using antimony trioxide catalyst after chain-extending with HDI. Without chain-extending, the molecular weight of PLA was about 7000 (M_n). T_m in the 2nd-scan DSC thermogram was not found when PLA was chain-extended with HDI. In order to check the degree of crystallization of polymers, annealing of these polymers was carried out at 120 °C. Peaks of XRD (X-Ray Diffraction) were sharpened as the duration of annealing was lengthened. The analysis of polymers reacted with HDI by ¹H-NMR showed the broad peaks at 1.32 and 3.14 ppm assigned to HDI units. The molecular weight of polymers increased with the increase in the mole ratio of-NCO/-OH.     

聚氨酯固化剂合成反应动力学

以具有三官能分枝的三羟甲基丙烷(TMP)为扩链剂,与甲苯二异氰酸酯(TDI)合成了聚氨酯固化荆.采用红外光谱(FT-IR)分析和化学滴定法分析反应体系中的-NCO浓度,考察了三羟甲基丙烷与甲苯二异氰酸酯的加成反应动力学.实验结果表明,当羟基浓度较大时,TDI与TMP反应遵循二级反应动力学.其表观二级反应速率常数随反应温度和羟基浓度的增加而增大.     

硅硼氮纤维前驱体聚合物的扩链反应改性

以柔性链遥爪聚合物[双(3-氨丙基)封端的聚二甲基硅氧烷(BTA-PDMS)]为扩链剂,对聚硅硼氮烷进行扩链反应改性,既可以提高其相对分子质量,又在刚性分子链中引入柔性链段,这显著改善了前驱体聚合物纤维的柔韧性,有望实现易退绕的目的。     

六官能UV固化聚氨酯丙烯酸酯的合成

以双季戊四醇(DPE),异佛尔酮二异氰酸酯(IPDI)和丙烯酸羟乙酯(HEA)为原料合成了六官能UV固化聚氨酯丙烯酸酯树脂(PUA)。研究了催化剂、反应物配比、反应温度和反应时间等对树脂合成的影响。通过实验得到了适宜工艺条件:反应物配比n(DPE)∶n(IPDI)1∶n(HEA)=1∶6∶6.72;催化剂为二月桂酸二丁基锡,阻聚剂为对羟基苯甲醚。第1步反应温度为60~65℃,反应时间为2 h,催化剂用量为DPE和IPDI总质量的0.085%;第2步反应温度为65~70℃,反应时间为2.5~3 h,催化剂用量为总投料质量的0.07%,阻聚剂用量为总投料质量的0.95%。     

Preparation of segmented, high molecular weight, aliphatic poly(ether-urea) copolymers in isopropanol. In-situ FTIR studies and polymer synthesis

The use of isopropanol (IPA) as the reaction solvent for the preparation of high molecular weight segmented polyether-urea copolymers based on cycloaliphatic diisocyanates was investigated. Reactivity of IPA with bis(4-isocyanatohexyl)methane (HMDI) and isophorone diisocyanate (IPDI) was studied between 0 and 40 °C using in-situ FTIR spectroscopy. HMDI, which has secondary isocyanate groups, shows a very slow reaction with a large excess of IPA at 0 and 23 °C. Analysis of the kinetic data indicates an activation energy of 51 kJ/mol for the reaction between HMDI and IPA. As expected, IPDI, which has both a primary and a secondary isocyanate (NCO) group, reacts faster with IPA compared with HMDI, which only has secondary NCO groups. However, the rate of reaction of IPDI with IPA at 0 °C is extremely slow (approximately 1% consumption of isocyanate in 60 min) thus allowing the use of IPA as the reaction solvent for polyether-urea synthesis. Preparation of high molecular weight, high-strength HMDI and IPDI based polyether-urea segmented copolymers in IPA has been demonstrated. Thermal analysis and stress-strain analyses were used to characterize the products.