瓜尔胶接枝高吸水性树脂的微波法合成

通过微波辐射法将丙烯酸和丙烯酰胺接枝到瓜尔胶的主链上,得到吸水性能优良的高吸水性树脂GAM。研究了微波辐射功率、辐射温度,辐射时间及丙烯酰胺用量对树脂吸液性能的影响规律,得到最佳工艺参数,此时树脂的最高吸水率为1454g/g,吸生理盐水率为169g/g,接枝率为980%。热重分析表明该高吸水性树脂耐热性优于瓜尔胶,证实发生了接枝聚合反应。     

丙烯酰胺-阳离子瓜尔胶的低温接枝聚合

用硫酸铈铵引发阳离子瓜尔胶与丙烯酰胺的低温(10℃)水溶液接枝聚合,重点研究单体与引发剂浓度对接枝参数的影响规律,获得了最佳聚合条件。实验表明,阳离子瓜尔胶与丙烯酰胺的聚合速度明显快于未改性瓜尔胶;随着单体浓度的增加,转化率、接枝率逐渐增加,接枝效率高达95%;进一步增加单体浓度(>1.3 mol/L),转化率、接枝率下降速度较快,接枝效率下降缓慢;随着引发剂浓度增加,转化率和接枝率增加到最大值,而引发剂浓度继续增加(>3.3×10-4mol/L),所有接枝参数下降。红外光谱图和热失重数据证实发生了接枝聚合反应。     

杜仲胶接枝甲基丙烯酸丁酯的合成与表征

采用溶液聚合工艺,以过氧化苯甲酰(BPO)为引发剂,成功制备了杜仲胶(EUG)和甲基丙烯酸丁酯的接枝共聚产物(EUG-g-BMA)。利用凝胶渗透色谱、核磁共振和红外光谱(IR)研究了接枝反应条件,如单体浓度、反应温度、引发剂浓度等对接枝共聚反应和接枝效率的影响。用差示扫描量热分析(DSC)研究了接枝率对产物熔融-结晶行为的影响。结果表明,当m(BPO)∶m(BMA)=0.05时,BMA浓度对接枝率和单体转化率影响明显,过高的反应温度导致交联产物的生成。IR谱图中1667 cm~(-1)处碳碳双键吸收峰的消失说明接枝反应发生在碳碳双键上。接枝改性导致杜仲胶分子链的结晶能力减弱。随着接枝率增加,产物的熔融温度和结晶温度向低温方向移动,结晶度降低;当接枝率达到17.6%时,DSC曲线上既不呈现熔融峰,也没有结晶峰,说明此时EUG-g-BMA已经完全失去结晶能力。     

甲基丙烯酸缩水甘油酯-苯乙烯多单体熔融接枝微孔聚丙烯

用单螺杆挤出机研究了甲基丙烯酸缩水甘油酯(GMA)-苯乙烯(St)多组分单体熔融接枝微孔聚丙烯(PP)体系。研究表明，以微孔型PP做接枝基体吸收接枝单体，能够大幅度提高单体的接枝率。当GMA和St的物质的量比约为16：8时，所得接枝物的接枝率最高，而此时接枝产物的熔体流动速率最小，二者有良好的对应关系。体系中所采用的PP具有特殊的微孔结构，使得单体接枝率获得极大提高。此外还探讨了单体用量比、温度和引发剂用量等因素对反应的影响。     

甲基丙烯酸与木薯淀粉接枝共聚反应研究

以硝酸铈铵为引发剂，以南方地区特有的木薯的淀粉与部分中的和甲基丙烯酸接枝共聚。研究了单体转化率，淀粉接枝率和接枝效率与甲基丙烯酸浓度。引发剂浓度，反应温度和时间，甲基丙烯酸中和度之间的关系。     

PA6与GMA接枝共聚纤维的结构和性能

本文采用IR、WAXD、SEM、DMA及DTA-TG等手段分析了聚己内酰胺与甲基丙烯酸缩水甘油酯接枝共聚纤维的结构和性能。该纤维枝链上含有大量具有反应性的环氧基,随接枝率提高,纤维序态及形态劣化,力学性能下降,在225℃附近,接枝纤维的枝链断裂,纤维在低于此温度下使用时是热稳定的。     

乳化剂对胶接枝共聚反应的影响

本研究了乳化剂（Ｅ）（１２８３，ＳＤＳ和１２８３＋ＳＤＳ）对明胶／丙烯酸丁酯（Ｇｅｌ／ＢＡ）、明胶／丙烯腈（Ｇｅｌ／ＡＮ）明胶／（丙烯酸丁酯－珍烯腈）（Ｇｅｌ／（ＢＮ－ＡＮ）接枝共聚反应的影响，提示出了这三种乳论剂的使用对明胶拉枝共聚反应的影响规律。对于Ｇｅｌ／ＢＡ三种乳化剂均合适，对于Ｇｅｌ／ＡＮ，Ｇｅｌ／（ＢＡ－ＡＮ），１２８３或不加乳化剂较为合适，本还研究了在不用乳化剂的条件下，乳化时间     

硝酸铈铵-乙二胺四乙酸引发壳聚糖与MAA和VAc接枝共聚合

以硝酸铈铵-乙二胺四乙酸为引发剂,在N2气的保护下,研究了壳聚糖与甲基丙烯酸(MAA)和醋酸乙烯酯(VAc)两种单体的接技共聚反应。考察反应时间、反应温度、甲基丙烯酸(MAA)和醋酸乙烯酯(VAc)两种单体不同质量浓度配比对接枝率的影响．结果表明．当C(CAN)=0．007mol／L、ρ(MAA)=6．7g／L、ρ(VAc)=6．7g／L、ρ(MAA)／p(VAc)=1：1、ρ(壳聚糖)=6．7g／L、在50℃反应2．5h,壳聚糖接技率较高。用红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜表征了接技共聚物。     

TEMPO促成的瓜尔胶及羟丙基瓜尔胶的选择性氧化

2,2,6,6-四甲基哌啶氧化物自由基(TEMPO)-NaClO-NaBr是一种新的具有很高选择性的氧化体系。文章研究了该体系在pH 9.30和体系温度为0℃时对瓜尔胶的氧化机理。用IR和13C-NMR表征了瓜尔胶及羟丙基瓜尔胶在氧化后的结构变化,证实了经氧化后(羟丙基)瓜尔胶结构中C6上伯醇可被选择性转化为羧基;另外在本实验条件下,随着瓜尔胶羟丙基取代度的增加,其氧化程度也增加。     

尼龙66纤维与丙烯酸的接枝共聚反应研究

以高锰酸钾／硫酸为引发剂，用尼龙６６纤维与丙烯酸进行接枝共聚，研究了尼龙６６纤维接枝率与硫酸浓度，高锰酸钾浓度，丙烯酸浓度，反应温度和时间，预处理时间之间的关系，实验结果表明，硫酸浓度为０．２ｍｏｌ／Ｌ，反应温度６０℃，反应时间４ｈ时，接枝率较高，尼龙６６纤维的预处理时间对接枝率的影响也较大。     

Myoglobin adsorption onto poly(glycidyl methacrylate) microbeads with surface functionalized iminodiacetic acid

In this study, poly(glycidyl methacrylate) [PGMA] microbeads with surface modified iminodiacetic acid (IDA) were used for myoglobin (Mb) adsorption from buffer solutions at different pHs and ionic strengths in a packed-bed column. Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) measurements before and after the adsorption process confirmed the structural stability of adsorbed Mb. The effects of initial concentration, flow-rate, pH and ionic strength on the adsorption were investigated. The results showed that the maximum amount of protein was adsorbed at a pH 7.0, which is the protein isoelectric point. The adsorption is rationalized in terms of local electrostatic forces acting between the protein and the IDA modified PGMA surface as well as hydrophobic interactions close to the protein isoelectric point, whereas at low pH the global changes give rise to protein–protein repulsion and at high pH protein-support material repulsion.     

Graft copolymerization of 2-vinyl pyridine and styrene onto isotactic polypropylene powder by the preirradiation method

Preirradiated isotactic polypropylene (IPP) powder has been modified by grafting 2-vinyl pyridine (2-VP) and styrene (Sty) in an aqueous medium. The graft copolymerization reaction was studied under different experimental conditions such as total dose, monomer concentration, amount of the solvent, time of reaction and temperature to determine the optimum conditions for affording maximum percentage of grafting (P_g). Maximum grafting percent of 2-VP (180%) and styrene (117%) was obtained under optimum conditions. The rate of grafting (R_g) of 2-VP and styrene has also been determined as a function of total dose, initial monomer concentration and the reaction temperature. From maximum P_g and different R_g values of 2-VP and Sty, 2-VP is more reactive towards grafting as compared to styrene under optimum conditions. Characterization of the graft copolymers is based on differential scanning calorimetric (DSC) analysis. Isolation of the grafted poly(2-VP) and poly(styrene) chains from the grafted samples provides an additional evidence of formation of the graft copolymer.     

Dielectric behaviour of glycidyl methacrylatebutyl methacrylate copolymers

Different copolymers of glycidyl methacrylate and butyl methacrylate with various compositions have been prepared by free radical polymerization. The composition of these copolymers was determined by¹H nuclear magnetic resonance technique. The dielectric properties of these compositions have been studied over a frequency range from 100 Hz to 50kHz and at different temperatures from 20 to 60 C.     

Radiation-induced grafting of glycidyl methacrylate onto cotton fabric waste and its modification for anchoring hazardous wastes from their solutions

Ion exchange adsorbents based on cellulosic fabric wastes carrying sulfonic acid and amine functional groups were synthesized by radiation-induced graft polymerization of glycidyl methacrylate (GMA) with subsequent chemical modification of the epoxy groups of poly-GMA graft chains with sodium sulfite/H₂SO₄ and triethylamine, respectively. The conversion of epoxy groups into the functional groups was investigated. Factors affecting on grafting process such as radiation dose, monomer concentration and solvent were studied. The synthesized adsorbent and its applications in the removal of different types of hazardous pollutants e.g. acidic dye, cobalt, dichromate and phenols from aqueous solution were also studied.     

Gelation of photopolymerized hyaluronic acid grafted with glycidyl methacrylate

Experiments have tracked the ambient gelation of a series of hydrophilic hyaluronic acid (HA) resins grafted with glycidyl methacrylate (GM) and photopolymerized as a function of dose. The resin mixtures range in GMHA concentration between 0.5 and 1.5% w/w in phosphate buffered saline (PBS). Illuminated at 20 mW/cm², the dynamic viscosity (η(t)) has been tracked and characterized using the Boltzmann log-sigmoidal model. A gelled viscosity of ~ 10 Pa s was determined at 0.5% w/w which rose to ~ 50 Pa s at or above 1% w/w. More curing agent marginally increased the gel viscosity at each concentration. Time constants associated with viscosity advancement were shortest at [GMHA] = 1.0%; higher concentrations are attributed with lower quantum efficiency when illuminated. Subsequent frequency sweeps replicated already published work using similar GHMA concentrations in PBS. G′ values ranged from 100 to 500 Pa over the formulation range with expected sensitivity to GMHA and curing agent concentration. Overall, the sigmoidal model represented this advancing viscosity data well, and further analysis of the physical significance of these model parameters may help in understanding photopolymerization of this complicated formulation more broadly.     

甲基丙烯酸缩水甘油酯改善木塑复合材料性能

选用甲基丙烯酸缩水甘油酯(GMA)作为偶联剂,探索了对杨木/塑料复合材料的力学性能和耐久性的改善;并利用SEM和FTIR分析了GMA加入苯乙烯单体(St)前后,高聚物与木材的界面复合效果与反应机制。SEM和FTIR的分析结果表明：GMA借助其自身的环氧基团,实现了与木材细胞壁上羟基的化学键合,且通过自身的双键实现了与单体St的共聚合,最终使高聚物与木材细胞壁较充分地实现了化学键联;高聚物以立体交联的形式填充于细胞腔中,与细胞壁紧密接触,无明显缝隙,复合效果良好。综合性能测试结果表明：GMA的加入,使改性木塑复合材料的静曲强度(MOR)、弹性模量(MOE)、顺纹抗压强度和硬度较未改性前分别提高45%、52%、71%和141%;尺寸稳定性较未改性前提高3倍;耐腐性较未改性前提高8.56倍。     

On the solid-state ageing behaviour of the polysaccharide,guar gum

Dilute solution viscometry was used to explore the effect of solid-state ageing on the interactions that occur between guar gum and water. The resulting data set, derived from nearly 700 independent experiments, led to a value for the Flory–Huggins interaction parameter, χ, of 0.56 ± 0.12. This value, which appeared independent of ageing, is in good agreement with the majority of published data. The effect of ageing on molar mass was also explored, using Mark–Houwink–Sakurada (MHS) theory. Absolute molar mass values were found to depend sensitively on the choice of MHS constants, but the effect of ageing was unequivocal; under all conditions, it resulted in a pronounced decrease in molar mass. In concert, these results strongly suggest that, in guar, solid-state ageing reactions are largely associated with scission of the molecular backbone. This hypothesis was then tested by infra-red and Raman spectroscopy. Although infra-red spectroscopy did reveal some subtle differences between the spectra of guar and locust bean gum (LBG), a related polysaccharides with a different galactose:mannose ratio, no equivalent effects were seen in aged guar. However, clear differences between the Raman spectra of guar and LBG were seen, demonstrating that the technique is well capable of revealing changes in galactose:mannose ratios. Examination of aged guar samples revealed no comparable effects, reinforcing the notion that, in this polysaccharide, chain scission reactions dominate such that solid-state ageing does not lead to changes in the nature of its interaction with water.     

2-羟基-3-丁氧基丙基胍胶的制备及流变性能

以胍胶原粉(GG)为原料,正丁基缩水甘油醚(BGE)为疏水化试剂,氢氧化钠为催化剂,异丙醇为溶剂,制备了2-羟基-3-丁氧基丙基胍胶(HBPG)。通过FT-IR、XRD、TGA对HBPG结构性能进行了表征,并研究了HBPG水溶液和冻胶的流变性能。结果表明,HBPG结构中由于引入疏水基团,使其结晶度下降,热稳定性能提高,HBPG相比GG具有更好的增稠性能,且溶液稳定性能得到明显改善,HBPG制备的冻胶的流变性能优于GG,具有良好的耐温和剪切稳定性能。     

Geotechnical properties of problematic expansive subgrade stabilized with guar gum biopolymer

Clean Technologies and Environmental Policy - This article presents a comprehensive study on the geotechnical behavior of problematic expansive subgrade stabilized by guar gum (GG) biopolymer. In...     

Studies on novel radiopaque methyl methacrylate: glycidyl methacrylate based polymer for biomedical applications

A new class of radiopaque copolymer using methyl methacrylate (MMA) and glycidyl methacrylate (GMA) monomers was synthesized and characterized. The copolymer was made radiopaque by the epoxide ring opening of GMA using the catalyst o-phenylenediamine and the subsequent covalent attachment of elemental iodine. The copolymer was characterized by Fourier transform infrared (FTIR) spectra, energy dispersive X-ray analysis using environmental scanning electron microscope (EDAX), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). X-ray visibility of the copolymer was checked by X-radiography. Blood compatibility and cytotoxicity of the newly synthesized copolymer were also evaluated. The iodinated copolymer was thermally stable, blood compatible, non-cytotoxic, and highly radiopaque. The presence of bulky iodine group created a new copolymer with modified properties for potential use in biomedical applications.