不同复配乳化剂合成乳液对汽车工业滤纸强度性能的影响

以苯乙烯和丙烯酸酯为主要单体,设计多种复配乳化剂方案,通过单体预乳化、半连续乳液聚合法合成苯丙乳液,用作汽车发动机空气滤清器滤纸浸渍树脂.研究了多种复配乳化剂合成苯丙乳液浸渍对汽车工业滤纸抗张强度、耐破度及挺度的影响,筛选出对滤纸强度性能作用效果良好的复配乳化剂.结果表明,合成乳液浸渍对提高汽车工业滤纸抗张强度、挺度及耐破度作用显著,OP-10/FR-1、OR-2/DSB、FOR-3/RE-610复配乳化剂乳液浸渍的汽车工业滤纸抗张强度高于3.15kN/m、挺度大于3.45 mN·m、耐破度在250 kPa以上.     

苯丙乳液合成中复配乳化剂对滤纸透气和耐水性能的影响

以苯乙烯和丙烯酸酯为主要单体,设计多种复配乳化剂方案,通过单体预乳化、半连续乳液聚合法合成苯丙乳液,用做汽车发动机空气滤清器滤纸浸渍树脂.实验研究了多种复配乳化剂合成苯丙乳液对滤纸透气度、耐水性能的影响,筛选对滤纸性能作用效果良好的复配乳化剂.结果表明,复配乳化剂合成苯丙乳液使滤纸透气度下降6%～11%,保持滤纸透气度...     

滤清器滤纸浸渍用苯丙乳液耐水性的研究

采用乳液聚合方法制备出以苯乙烯、丙烯酸丁酯(BA)为主体,加入其他功能性单体共聚的苯丙乳液.探讨了共聚单体组成、乳化剂以及交联剂对乳液成膜和经乳液浸渍滤纸的耐水性和物理机械性能的影响.结果表明,加入疏水性的共聚单体或乳化剂均可以有效地提高乳液成膜和经乳液浸渍滤纸的耐水性、强度和挺度.此外,交联剂浓度的增加也可以使胶乳成膜后的耐水性及经乳液浸渍滤纸的耐水性、强度及挺度有所提高.     

汽车工业滤纸水溶性浸渍树脂的研制

以苯乙烯为硬单体,丙烯酸丁酯为软单体,单体A和单体B为功能性单体,采用半连续乳液聚合法合成苯丙乳液,对乳液合成条件进行了研究,对乳液和浸渍后汽车工业滤纸性能进行了检测、分析。得到合成乳液最佳乳化剂用量2.0%,引发剂用量2.0%,反应温度为77℃,搅拌强度为400r·min~(-1);最佳单体的配比为:苯乙烯∶丙烯酸丁酯∶单体A∶单体B为60%∶40%∶5%∶3%;乳液平均粒径0.145μm,粒度分布均匀。浸渍后滤纸的性能指标是:耐破度320kPa,耐水性99min,透气度350L·m~(-2)·s~(-1),达到国内同类产品先进水平。     

松香乳液增强汽车滤纸耐水性的研究

该文以苯丙乳液为母液,加入两种来源不同的松香乳液进行复配,制备汽车滤纸浸渍液,对滤纸原纸进行浸渍制备汽车滤纸,通过测试滤纸的耐水性、耐破度等性能指标来分析松香乳液对汽车滤纸耐水性能的影响,确定松香乳液的种类和复配工艺。     

硅-苯丙乳液改善浸渍滤纸的憎水性能

在引入具有交联作用的甲基丙烯酰氧丙基(三甲氧基)硅烷(KH-570)的基础上,以有机锡为缩合催化剂,将羟基硅油接枝到苯丙乳液体系的侧链上,合成了有机硅改性苯丙乳液(简称硅-苯丙乳液),用红外光谱(FT-IR)对合成乳液进行分析,证明有机硅单体参与了共聚.用硅-苯丙乳液和商品PR型乳液(纯苯丙乳液)对滤纸原纸进行浸渍处理,结果表明,经硅-苯丙乳液浸渍的滤纸,透气度没有明显下降、力学性能得到改善,且有较好的憎水性能.     

聚乙二醇改性三聚氰胺甲醛树脂对汽车空气滤纸性能的影响

采用聚乙二醇对三聚氰胺甲醛树脂进行改性,改性后的树脂用作交联剂添加到苯丙乳液中,并对汽车工业滤纸原纸进行浸渍加工处理。通过研究聚乙二醇(P)、三聚氰胺(M)、甲醛(F)的不同配比、树脂添加量及固化pH值,探讨了其作为乳液交联剂对汽车工业空气滤纸的抗张强度、耐破度、耐水性、透气度的影响。实验结果表明,当P与M的摩尔比为0.32,F与M-MP的摩尔比为2.8,改性树脂添加量为苯丙乳液固含量的4%,固化pH值为6～7时,汽车工业空气滤纸的综合性能最佳(苯丙乳液的上胶量为25%)。当pH值为6时,滤纸的抗张强度为4.51 kN/m,耐破度为340 kPa,耐水性为39.4min,透气度为334 L/(m2.s)。     

功能性单体对苯丙乳液在汽车工业滤纸中的应用效果

以苯乙烯和丙烯酸酯为主要单体,引入功能性单体,采用预乳化半连续乳液聚合法制备改性苯丙乳液,探讨了功能性单体对乳液性能及其在滤纸中的应用效果.结果表明,当丙烯酸用量在4%～6%时,滤纸的耐水性、强度性能最佳;亚甲基双丙烯酰胺用量在2%时,滤纸的耐水性能好,单体转化率高,滤纸强度性能、透气度等综合性能较好;N-羟甲基丙烯酰胺对改善滤纸的耐水性及强度性能显著,不过对滤纸透气性能有较大影响,当其用量为2%时,表现出最佳综合效果;当衣康酸用量在2%时,滤纸的强度性能提高较大,且对保持滤纸透气度有良好的作用,但对提高滤纸耐水性作用较小.     

苯丙乳液中硅烷偶联剂对浸渍滤纸性能的影响

用乙烯基三甲氧基硅烷与苯乙烯、丙烯酸酯共聚合成苯丙乳液,对乳液性能进行了检测,并用傅里叶红外光谱对乳液化学结构进行了表征,证明乙烯基三甲氧基硅烷参与了共聚物的合成。用所合成的苯丙乳液对汽车工业滤纸原纸进行浸渍处理,结果表明,随苯丙乳液中乙烯基三甲氧基硅烷含量的增加,滤纸机械强度、耐水性均有提高,透气性略有降低。浸渍乳液加入三聚氰胺甲醛树脂能改善滤纸综合性能。     

酚醛树脂合成条件及其与苯丙乳液复配体系对浸渍滤纸性能的影响

介绍一种苯丙乳液与酚醛树脂复配体系,针对酚醛树脂合成过程中用碱量和保温时间不同,研究并比较滤纸用酚醛-苯丙乳液复配体系和纯乳液分别浸渍增强后的多项力学性能。结果发现:酚醛树脂用碱量为11%,保温时间为3.5h,复配体系浸渍固化滤纸后力学性能相对乳液浸渍的滤纸有较大幅度的提高,其中耐破度可提高20%,抗张强度、伸长率和挺度均有不同程度的提高,达到了既降低成本又提高滤纸力学性能的目的,对工业应用有指导意义。     

乳状液成分对O/W乳状液性质的影响

采用单因素实验设计,通过机械搅拌方法制备O/W乳状液。通过乳状液的离心稳定性、粘度和乳状液的显微结构,研究不同HLB值的复合乳化剂及含量、脱脂乳粉溶液的浓度以及油和水比例对乳状液性质的影响,最终确定较佳的乳状液成分。实验结果表明:当以Span-80和Tween-80为复合乳化剂,其HLB值为9.6、复合乳化剂含量为16%(w/w)、脱脂乳粉溶液浓度为25%(w/v)、油与水比为1∶1(w/w)时,可以获得状态较好的乳状液,此时乳状液的离心稳定性最高,可以达到97.5%。     

Hydrophobins stabilised air-filled emulsions for the food industry

Hydrophobin HFBII has been extracted from a culture of Trichoderma reesei. The protein has been used to construct air cells of approximately 1–100 μm in size, with approximately 40% of the air cells falling within the 1–2 μm range. We have termed these suspensions air-filled emulsions and propose their use for fat replacement in emulsion based food structures. The air cells in the air-filled emulsion have a surface elasticity, given by the hydrophobin film that helps prevent disproportionation and ripening. The air-filled emulsions show little if any change in individual air cell size when stored for up to 4 months at room temperature. Moreover the interface to the air cells is robust and capable of surviving long, high shear processing steps. Production of the hydrophobin film is an extremely rapid event and ordinarily it is difficult to control during emulsion formation. Here we have used a sonication process to produce the air cells. This process then allows us to control the hydrophobin assembly kinetics in order to ensure that they are not removed from the interface after aggregation, and thus rendered inactive. Using the air-filled emulsions we have created a, so called, tri-phasic system with up to 60% included phase of air and oil in an aqueous continuum and showing a greater than 50% reduction in lipid content when compared to a rheologically similar oil water emulsion. The tri-phasic emulsions are stable for up to 45 days in terms of droplet size and with no loss of air phase.     

Study on effect of blend ratio on thermal comfort properties of cotton/nylon-blended fabrics with high-performance Kermel fibre

This study presents the thermal comfort properties of woven fabrics made of Kermel, cotton/nylon and cotton/nylon /Kermel-blended yarns. Our aim in this study is to combine the high comfort properties of cotton/nylon fibres with high thermal protective properties of Kermel fibre in different woven fabrics. Thus, Kermel (100%), cotton/nylon (50:50) and four blends of the 50% cotton fibres with nylon and Kermel (40:10, 30:20, 20:30 and 10:40) were spun on a ring-spinning frame and twisted into two-folded yarns with the same yarn count of 30/2(Ne) and twist level of 560 TPM. Using the produced yarns, woven fabrics with identical characteristic and structure were also produced. Then, the thermal comfort and physical properties of fabrics were studied in terms of fabric porosity, thermal resistance, thermal conductivity, water vapour resistance and air permeability. The results show that the porosity, air permeability and thermal resistance increase with Kermel fibre blend ratio. Conversely, the water vapour resistance decreases with increase of Kermel fibre blend ratio up to 40%, while 100% Kermel-woven fabric exhibits a higher water vapour resistance value. Nevertheless, the thermal conductivity of cotton/nylon-blended Kermel woven fabric is unchanged with increase of Kermel fibre blend ratio up to 40%, whereas at 100% Kermel fibre blend ratio, the lowest thermal conductivity is obtained. The obtained results implied that woven fabric produced from cotton/nylon (50/10) blended with 40% Kermel fibre resulted in proper thermal comfort properties.     

Iron‐mediated lipid oxidation in 70% fish oil‐in‐water emulsions: effect of emulsifier type and pH

The objective of this study was to investigate the protective effect of five different emulsifiers on iron‐mediated lipid oxidation in 70% fish oil‐in‐water emulsions. The emulsifiers were either based on protein (whey protein isolate and sodium caseinate) or based on phospholipid (soy lecithin and two milk phospholipids with different phospholipid contents, MPL20 and MPL75). Lipid oxidation was studied at pH 4.5 and 7.0, and results were compared to lipid oxidation in neat fish oil. Results showed that all emulsions oxidised more than neat oil. Furthermore, emulsions prepared with proteins oxidised more at low pH than at high pH, and casein emulsions oxidised the least (Peroxide value (PV) at day 7 was 0.5–0.7 meq kg^?1). Among emulsions prepared with phospholipids, emulsions with MPL75 were the most oxidised followed by emulsions prepared with lecithin and MPL20. Thus, PV in MPL75 emulsions was 5.0–5.5 meq kg^?1 at day 7 compared with 0.9–1.9 meq kg^?1 in MPL20 emulsions.     

Influence of Surfactants on the Rheological Behavior of Starch/Gelatin Gels and Gel-Emulsions

Thixotropic behavior of mixed 8% starch/gelatin gels and gel-emulsions (8% of the sunflower oil dispersed in the starch/gelatin gel), prepared with the addition of different emulsifiers, by means of the rotational viscometer with coaxial cylinders, has been investigated. Different emulsifiers (Na-dodecyl sulfate, cetyl alcohol, mono- and diglycerides of fatty acids and alkyl polyglycolethers) were applied before (at 40°C) and after (at 96°C) gelatinization of the starch. Thixotropic properties, i.e. the coefficients of thixotropy of gels and emulsions were determined by the thixotropic loop method. Samples were taken in different time intervals (up to 72 h), in order to investigate the ageing effects. Very stable gels and gel emulsions (containing carbohydrate, protein and fatty component), with high aging stability can be obtained.     

Effect of emulsifier type on sensory properties of oil-in-water emulsions

This work investigates the fundamental properties of emulsifiers that may contribute to the fat-associated sensory attributes of emulsions. Model oil-in-water emulsions were prepared with 0, 12, 24, 36 and 48% oil and emulsified with seven different emulsifiers; two proteins; sodium caseinate and whey protein, and five different sucrose esters. Emulsions were rated for perceived ‘fat content’, ‘creaminess’ and ‘thickness’ on nine-point category scales. Instrumental measurements of particle size, viscosity, thin film drainage, surface dilational modulus and interfacial tension were made. The sensory results indicate significant main and interactive effects of fat level and emulsifier type. At higher fat levels, emulsions prepared with sodium caseinate and whey protein emulsifiers had higher viscosities and higher sensory scores than those prepared with the sucrose esters. Results indicate that emulsifier type has a significant effect on the sensory properties of oil-in-water emulsions, and relationships between instrumental and sensory measures suggest that this may be due to the interfacial properties of emulsifiers at the oil–water interface. © 1998 SCI.     

Production of O/W Emulsions Containing Astaxanthin by Repeated Premix Membrane Emulsification

ABSTRACT: Oil-in-Water (O/W) emulsions are mainly produced by application of high mechanical stress or by membrane emulsification processes at low pressures. Advantages such as narrower droplet size distribution and lower operating costs make membrane emulsification processes more suitable for producing astaxanthin-loaded O/W emulsions. The characteristics of 1 of these membrane emulsification methods, called repeated premix membrane emulsification, are studied in this work. In this emulsification process, a pre-emulsion is repeatedly pushed through a hydrophilic or hydrophobic membrane. In this research, ahydrophilic membrane was used because the objective was to obtain an O/W emulsion. Pre-emulsions were produced by dispersing palm oil containing dissolved astaxanthin in water. The oil droplets were stabilized with a combination of 2 emulsifiers. Each O /W emulsion passed the membrane 3 times underpressures and disperse phase fractions of 5 to 15 bar and from 10 wt% to 40 wt%, respectively. To investigate the production of O/W emulsions by repeated premix membrane emulsification, mean Sauter diameters and fluxes were measured. To find the optimal ranges of pressure and dispersed phase fraction, a "2-level factorial design with central composite and stars points" experimental design was applied.     

Effects of bacteriostatic emulsifiers on stability of milk-based emulsions

For milk-based emulsion products such as canned coffee or tea, the addition of bacteriostatic emulsifiers is necessary to inhibiting the growth of heat-resistant sporeformers. Since bacteriostatic emulsifiers often cause the destabilization of emulsions, other type of emulsifiers, such as stability-enhancing ones, are necessary for the long-term stability of emulsions. Four milk-based emulsions were prepared from powdered milk combined with several types of emulsifiers. The long-term stability of emulsions, which was detected by the occurrence of a creaming layer after 3 months of storage, differed according to the composition of emulsifiers. To understand the reason for the differences in the stability of emulsions, particle size, distribution, ζ-potential, and the amount of proteins and phospholipids present in the cream layer (separated oil droplets) in the emulsions were measured. Only the amount of proteins adsorbed onto oil droplets was found to be closely related to the difference in emulsion stability, that is, the more proteins adsorbed, the higher the emulsion stability. SDS–PAGE analyses revealed that κ-casein and β-lactoglobulin play an important role in emulsion stability by adsorbing onto the oil droplet surface.     

Physical and Mechanical Properties of Pea Starch Edible Films Containing Beeswax Emulsions

ABSTRACT:  Hydrophobic beeswax emulsions were incorporated into hydrophilic starch films to modify physical, mechanical, and thermal properties of the films. Beeswax was added in the film-forming solution of high-amylose pea starch (35% to 40% amylose w/w) at the level of 0%, 10%, 20%, 30%, and 40% w/w of starch with glycerol as a plasticizer (40/60 of glycerol/starch). Addition of beeswax affected mechanical properties, significantly reducing tensile strength and elongation and increasing elastic modulus. Beeswax addition decreased water vapor permeability and increased oxygen permeability. However, the addition of hydrophobic wax particles in starch films marginally affected these physical properties below 30% beeswax in the films. Beeswax addition at the 40% concentration formed amylose–lipid complex that caused the dramatic changes of physical and thermal properties of the films.     

C16OH／AEO-3混合分子膜抑制水分蒸发的研究

探讨了C16OH／AEO-3复配比例、温度、时间、环境因素等对分子膜抑制水分蒸发效果的影响。研究结果表明,当温度为25℃,膜表面浓度为8．0×10^2g／m^2时,C16OH的抑制率最高仅为35％,引入AEO-3后,当C16OH／AEO-3的复配比例为7：3时,抑制率最高可达60％以上。室外实验表明,混合膜在膜表面浓度为4．0×10^-1g／m^-2时,15d后仍有一定的抑制效果,抑制率依旧保持在30％以上。此外,在15℃-40℃的温度范围内,混合膜的抑制率高于C16OH,显示出更好的抑制水分蒸发能力。透气性测试结果表明,C16OH和混合膜均不妨碍气水界面的氧气交换。分子膜的AFM图像显示,混合膜能形成比C16OH更为凝聚的分子膜,产生更为理想的抑制水分蒸发效果。