An Investigation Into the Formation of Plasticizer Channels in Plasticized Polymer Films

The effects of plasticizer, polyethylene glycol (PEG-600), on the sucrose permeability, void volume and morphology of cellulose acetate free films were investigated. The sucrose permeability of cellulose acetate free films was found to decrease with increasing PEG-600 to a minimum and increase dramatically when they were plasticized by over 30% (w/w) PEG-600. The decrease in sucrose permeability of cellulose acetate free films with increasing plasticizer at low plasticizer concentrations could be interpreted by the antiplasticization effect, and the dramatic increase of sucrose permeability of cellulose acetate free films at high plasticizer level could be explained by the formation of plasticizer channels. The void volume of cellulose acetate free films were calculated by determining the water content in the films, and the effect of PEG-600 on the morphology of cellulose acetate free films was studied by using the scanning electron microscopy (SEM). Both the void volume and SEM studies supported the assumption that the plasticizer channels would be formed in the polymer films which contain high concentration of plasticizer.     

Effects of Plasticizers on Water Permeation and Mechanical Properties of Cellulose Acetate: Antiplasticization in Slightly Plasticized Polymer Film

Abstract

The effects of plasticizers, triacetin and three different molecular weights of polyethylene glycol, on the water permeation and mechanical properties of cellulose acetate were investigated. At 37°C, the water permeability of cellulose acetate was found to decrease with increasing plasticizer to a minimum and then to increase with higher concentrations of plasticizer. Low plasticizer concentrations caused a decrease in water permeability by antiplasticization. Antiplasticization arose from an interaction between the polymer and the plasticizer molecules and decreases the molecular mobility of the polymer. This effect was confirmed by mechanical measurements of polymer free films at the same experimental temperature. However, when the temperature was raised above the glass transition temperature, T_g, of the polymer films, the polymer films contain enough energy to overcome the interaction between the polymer and plasticizer molecules, and the antiplasticization effect disappeared.     

Effects of Plasticizers on Water Permeation and Mechanical Properties of Cellulose Acetate: Antiplasticization in Slightly Plasticized Polymer Film

The effects of plasticizers, triacetin and three different molecular weights of polyethylene glycol, on the water permeation and mechanical properties of cellulose acetate were investigated. At 37°C, the water permeability of cellulose acetate was found to decrease with increasing plasticizer to a minimum and then to increase with higher concentrations of plasticizer. Low plasticizer concentrations caused a decrease in water permeability by antiplasticization. Antiplasticization arose from an interaction between the polymer and the plasticizer molecules and decreases the molecular mobility of the polymer. This effect was confirmed by mechanical measurements of polymer free films at the same experimental temperature. However, when the temperature was raised above the glass transition temperature, T_g, of the polymer films, the polymer films contain enough energy to overcome the interaction between the polymer and plasticizer molecules, and the antiplasticization effect disappeared.     

Studies of the drug permeability and mechanical properties of free films prepared by cellulose acetate pseudolatex coating system

Free films produced with cellulose acetate (CA) pseudolatex were prepared by the casting method. The effects of plasticizer concentration, drying temperature, and drying time on drug permeability and mechanical properties of free films were investigated by three-factor spherical second-order composite experimental design. The results were analyzed by the multivariable regression method. The experimental results indicated that plasticizer concentration, drying temperature, and drying time had complex effects on free film permeability and mechanical behavior. These results probably arise from the film-forming ability of CA pseudolatex particles at various conditions and the evaporation of plasticizer during the film-forming process     

The Influence of Different Plasticizers and Polymers on the Mechanical and Thermal Properties,Porosity and Drug Permeability of Free Shellac Films

ABSTRACT

The effect of triethyl citrate (TEC) and different molecular weights and concentrations of polyethylene glycol (PEG), in addition to the effect of different water-soluble polymers and dispersions at different levels, hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), carbomer 940, polyvinyl alcohol (PVA), ethyl cellulose (EC), on the mechanical and thermal properties, drug permeability, and porosity of free shellac films were investigated. Shellac films were cast from aqueous solutions, and their mechanical properties were studied by tensile test. Thermal analyses were performed using differential scanning calorimetry (DSC).

The results showed that the addition of plasticizer caused a decrease in both elastic modulus and glass transition temperature (T_g) and an increase in elongation at break of free shellac films. This effect was related to the concentrations of plasticizers. Different molecular weights of PEGs have different plasticization mechanisms.

Moreover, the incorporation of different amounts of HPMC, MC, or carbomer in free shellac films caused an increase in the flexibility, decrease in T_g, and a marked increase in drug permeability of free shellac films, whereas the addition of PVA caused a decrease in flexibility and drug permeability and an increase in T_g. Addition of EC resulted in a slight decrease of the elasticity and a small decrease in drug permeability. However it does not show a considerable effect on the T_g. In addition, it was found that the drug permeability is directly related to the mechanical properties and T_g of shellac films.     

The influence of different plasticizers and polymers on the mechanical and thermal properties, porosity and drug permeability of free shellac films

The effect of triethyl citrate (TEC) and different molecular weights and concentrations of polyethylene glycol (PEG), in addition to the effect of different water-soluble polymers and dispersions at different levels, hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), carbomer 940, polyvinyl alcohol (PVA), ethyl cellulose (EC), on the mechanical and thermal properties, drug permeability, and porosity of free shellac films were investigated. Shellac films were cast from aqueous solutions, and their mechanical properties were studied by tensile test. Thermal analyses were performed using differential scanning calorimetry (DSC).

The results showed that the addition of plasticizer caused a decrease in both elastic modulus and glass transition temperature (T_g) and an increase in elongation at break of free shellac films. This effect was related to the concentrations of plasticizers. Different molecular weights of PEGs have different plasticization mechanisms.

Moreover, the incorporation of different amounts of HPMC, MC, or carbomer in free shellac films caused an increase in the flexibility, decrease in T_g, and a marked increase in drug permeability of free shellac films, whereas the addition of PVA caused a decrease in flexibility and drug permeability and an increase in T_g. Addition of EC resulted in a slight decrease of the elasticity and a small decrease in drug permeability. However it does not show a considerable effect on the T_g. In addition, it was found that the drug permeability is directly related to the mechanical properties and T_g of shellac films.     

Preparation and Characterization of Cellulose Acetate Butyrate/Organoclay Nanocomposites Produced by Extrusion

Nanocomposite films based on cellulose acetate butyrate, modified montmorillonite (Cloisite^® 30B), plasticizer (triethyl citrate) and antimicrobial compounds (carvacrol and cinnamaldehyde) were prepared by extrusion. The effects of the Cloisite^® 30B content and antimicrobial compound types on the morphology of the nanocomposite films were investigated by X‐ray diffraction and transmission electron microscopy. The thermal characteristics of films were analysed by thermogravimetry and differential scanning calorimetry; oxygen and water vapour permeability and tensile strength were determined. The film's antimicrobial behaviour against Listeria innocua, Staphylococcus aureus, Escherichia coli O157:O7 and Saccharomyces cerevisiae was investigated and determined using a viable cell count method. Nanocomposites with a Cloisite^® 30B content of 3 wt% showed better dispersion than nanocomposites with a 5 wt% content. For films with antimicrobial compounds, tensile strength and Young's modulus decreased and water vapour permeability increased (150%) because of the plasticization effect of the antimicrobial compounds (essential oils). The nanocomposites with carvacrol and cinnamaldehyde were effective against the tested Gram‐positive bacteria (reduction of at least 3.0 log CFU/ml) and yeast (reduction of at least 4.0 log CFU/ml). This study demonstrates that antimicrobial cinnamaldehyde and carvacrol can be successfully incorporated into cellulose acetate butyrate nanocomposites and that they have an inhibitory effect against microbial growth in solid medium. It shows the potential use of cellulose acetate butyrate for food packaging applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of plasticizers on the properties of oat starch films

Oat starch films were prepared by casting using glycerol, sorbitol, glycerol–sorbitol mixture, urea and sucrose as plasticizers. The effects of these plasticizers on the microstructure, moisture sorption, water vapor permeability (WVP) and mechanical properties were investigated using films stored under a range of relative humidities. The plasticizer type did not affect significantly (p ≤ 0.05) the equilibrium moisture content of films, except at 90% relative humidity (RH). Films without plasticizer adsorbed less water and showed higher WVP than plasticized ones, indicating the antiplasticizing effect observed in this work. In general, a decrease in stress at break and Young's modulus and an increase in strain at break were observed when RH increased in all film formulations. Films without plasticizer showed higher stress at break values than the plasticized ones and presented stable strain at break under a range of RH. Sucrose films were the most fragile at low RH while glycerol films were the most hygroscopic.     

甘油含量对NMMO工艺天然纯纤维素膜性能的影响

以棉纤维素为原料,以NMMO(N-甲基吗啉-N-氧化物)为溶剂,以甘油为增塑剂制取天然纯纤维素包装膜,研究了不同甘油含量对纤维素膜性能的影响。结果表明,随着甘油含量的增加,纤维素膜的断裂伸长率随之增加,拉伸强度随之降低,二者变化幅度都很大;当甘油含量从2%增加到5%,纤维素膜的透油系数增加了13.4%,氧气透过率增加了3.0%,透湿系数增加了16.7%,透光率增加了22.4%,横向热收缩率增加了58.8%,纵向热收缩率增加了54.7%。可见,甘油含量对膜的透氧性影响较为微弱,但对力学性能、透油性、透湿性、透明度、热收缩率影响均较为显著。     

Valuation of a Cellulose Acetate (CA) latex as coating material for controlled release products

Abstract

Cellulose acetate (CA) latex plasticized with 150% triacetin (TA) and 120% triethylcitrate (TEC), based on polymer weight, provided dense and homogeneous films when deposited onto propranolol HCl tablets using conventional fluid bed technology. Film permeability to the drug was low and flux/permeability enhancers were added to the CA structure during its manufacture. Films containing 40% surcrose and 10% PEG 8000 were found to provide the best release characteristics in terms of small lagtime (1 hour) and drug release profile (over 12 hours). When sucrose was added to TA or TEC plasticized fimls, a macroporous membrane was created during exposure to the dissolution fluid due to sucrose release from the film. These observations are consistent with the controlled porosity walls previously described for CA films deposited from organic solvents. It was postulated that drug mass transport occurs mainly within the porous CA structure and the mechanism responsible for its is a combination of molecular diffusion/osmotic pressure via water transport into the porous cellulose acetate membrane. Plasticizer loss during drying had also been demonstrated and related to the change in release profile seen with drying time.     

Effects of glycerol and sorbitol on optical,mechanical, and gas barrier properties of potato peel‐based films

Potato peel is a by‐product of potato‐based food production and seen as a zero‐ or negative‐value waste of which millions of tons are produced every year. Previous studies showed that potato peel is a potential material for film development when plasticized with 10% to 50% glycerol (w/w potato peel). To further investigate potato peel as a film‐forming material, potato peel‐based films containing the plasticizer sorbitol were prepared and investigated on their physicochemical properties in addition to films containing glycerol. Due to sufficient producibility and handling of casted films in preliminary trials, potato peel‐based films containing 50%, 60%, or 70% glycerol (w/w potato peel) and films containing 90%, 100%, or 110% sorbitol (w/w potato peel) were prepared in this study. Generally, with increasing plasticizer concentration, water vapor and oxygen permeability of the films increased. Films containing glycerol showed higher water vapor and oxygen permeabilities than films containing sorbitol. Young's modulus, tensile strength, and elongation at break decreased with increasing sorbitol concentration, whereas no significant effect of plasticizer content on elongation at break was shown in films containing glycerol. Due to crystallization of films containing sorbitol as a plasticizer, potato peel‐based films containing 50% glycerol (w/w) were identified as the most promising films, characterized by a water vapor transmission rate of 268 g 100 μm m^?2 d^?1 and an oxygen permeability of 4 cm³ 100 μm m^?2 d^?1 bar^?1. Therefore, potato peel‐based cast films in this study showed comparable tensile properties with those of potato starch‐based films, comparable water vapor barrier with those of whey protein‐based films, and comparable oxygen barrier with those of polyamide films.     

增塑剂对马铃薯淀粉基复合膜物理机械性能的影响

以马铃薯淀粉、普鲁兰多糖、明胶为成膜物质,氯化钙为交联剂,甘油、山梨醇、聚乙二醇为增塑剂,采用流延法制备了马铃薯淀粉基复合膜,研究了3种增塑剂对复合膜物理机械性能的影响。结果表明:复合膜的抗拉强度和弹性模量均随增塑剂含量的增加而显著减小,断裂伸长率随甘油和山梨醇含量的增加而显著增加,聚乙二醇对其影响不显著;复合膜的水蒸气透过率和水溶性均随增塑剂含量的增加而增加;聚乙二醇能够显著降低复合膜的透光率。     

Bitterness reduction in grapefruit juice through active packaging

Naringin and limonin are the principle bitterness components of citrus juices. Our objective was to determine if the perceived bitterness in grapefruit juice could be reduced during storage through interaction with active packaging film. Storage of 10° Brix grapefruit juice at 7°C in contact with fungal-derived naringinase immobilized on cellulose acetate film reduced bitterness as perceived by a sensory panel. The films reduced naringin and limonin concentration by hydrolysis and adsorption respectively. Reduction in the naringin and limonin content of grapefruit juice by cellulose acetate films containing immobilized enzyme from 600–400 mg/l and 8.0–6.7 mg/l respectively could be detected as a reduction in bitterness by a sensory panel (p < 0.10). As the area of film (cm²)/volume of juice (ml) ratio increased from 1.1 to 3.6, the time to decrease the naringin level decreased. The reduction in naringin was not affected by agitation or holding the samples quiescently. The amount of enzyme desorbed from the film represented only 2% of the amount of enzyme immobilized in the film. The reduction in bitterness comes from direct interaction with the active packaging films. © 1998 John Wiley & Sons, Ltd.     

Properties of Aqueous, Plastic Izer-Containing Ethyl Cellulose Dispersions and Prepared Films in Respect to the Production of oral Extended Release Formulations

Plasticized aqueous ethyl cellulose (EC) dispersions (Aquacoat^R ECD-30) are incompatible with concentrated electrolytes but stable with nonelectrolytes. The minimum film formation temperature (MFT) decreases with increasing plasticizer content, from 81°C to about 30°C with 20% dibutyl sebacate (DBS) in the resulting film. The plasticiser has to penetrate completely into the EC particles before film formation to obtain optimal plastification, the lowest film formation temperature and high permeability of the resulting film. This takes more than 5 hours with 20% DBS. Films prepared from plasticized dispersion with short standing times show craters of former plasticizer droplets. With increasing plasticizer content the sticking point of the films decreases. The plasticizer induce a high water absorption of the films: more than 30% with 23-26% DBS or diethyl phthalate (DEP). DBS is hardly released from the films within 5 hours, in contrast to DEP. Thus, the absorbed water is completely swelling water in case of DBS and partially also substitution water in case of DEP. The films squeeze out cetylalcohol (CA) and also sodium lauryl sulfate (NaLS) during storage, this may change the permeability of the films. EC contains a small amount of carboxylic groups which explains the pH dependent release of drugs from pellets coated with aqueous EC dispersions.     

纳米纤维素/壳聚糖复合膜的制备和性能

目的获得力学性能和阻隔性能优异的食品包装用壳聚糖膜。方法通过超声法由糠醛渣纤维素制备纳米纤维素(NCC),将其与壳聚糖(CS)共混流延制备纳米纤维素/壳聚糖复合膜(NCC-CS)。结果复合膜中NCC质量分数为5%时,NCC-CS的拉伸强度比纯CS膜提高了30%,NCC-CS的透湿量比纯CS膜降低了24%。SEM分析结果表明NCC-CS复合膜微观结构致密。FT-IR和XRD的分析结果表明CS与NCC间存在着较强的相互作用。结论 NCC的加入对CS膜的力学性能和阻隔性能的提高有促进作用。     

Conductivity studies of plasticized PEO-Lithium chlorate–FIC filler composite polymer electrolytes

A new report of the synthesis of (PEO/plasticizer)LiClO₄–Li_1.3Al_0.3Ti_1.7(PO₄)₃ polymer electrolyte films prepared by the solution-cast technique is represented in this work. DSC trace revealed that T_g decreased with the increase of plasticizer content in the polymer electrolyte films. SEM morphology showed that the surface morphology of films was relatively smooth and homogeneous. Conductivity studies by EIS measurement indicated that the temperature dependence of ionic conductivity of films followed Vogel–Tamman–Fulcher (VTF) equation. The pre-exponential factor (A) and the pseudo activation energy (E_a) increased with the increase of plasticizer content in the polymer electrolyte films. At the 40 wt.% plasticizer content, A and E_a respectively had a maximum.     

多孔超细醋酸纤维/涤纶非织造布复合滤材的制备及性能

采用静电纺丝技术,借助高挥发溶剂的制孔性,通过调控二醋酸溶液的浓度,制备了串珠状、条带状和圆柱状的多孔二醋酸超细纤维。通过扫描电镜观察纤维形貌,通过电导率仪测试纺丝液电导率,运用黏度计测试纺丝液黏度,利用滤料综合性能测试台测试纤维形貌、纺丝时间及空气流量对复合滤料过滤性能的影响。实验结果表明,随溶液浓度增加,多孔纤维形貌可由"串珠状"过渡到"条带状"最终变为"圆柱状",条带状纤维和圆柱状纤维有利于提高纤维的过滤效率,而串珠状纤维有利于降低复合滤料的过滤阻力;随着纺丝时间的延长,复合滤料的过滤效率和过滤阻力均呈增大趋势;随着空气流量的增加,复合滤料过滤效率略有降低,而其过滤阻力增加明显。     

New biocomposites based on thermoplastic starch and bacterial cellulose

Bacterial cellulose, produced by Acetobacter Xylinum, was used as reinforcement in composite materials with a starch thermoplastic matrix. The composites were prepared in a single step with cornstarch by adding glycerol/water as the plasticizer and bacterial cellulose (1% and 5% w/w) as the reinforcing agent. Vegetable cellulose was also tested as reinforcement for comparison purposes. These materials were characterized by different techniques, namely TGA, XRD, DMA, tensile tests, SEM and water sorption assays. All composites showed good dispersion of the fibers and a strong adhesion between the fibers and the matrix. The composites prepared with bacterial cellulose displayed better mechanical properties than those with vegetable cellulose fibers. The Young modulus increased by 30 and 17 fold (with 5% fibers), while the elongation at break was reduced from 144% to 24% and 48% with increasing fiber content, respectively for composites with bacterial and vegetable cellulose.     

乙酸纤维素游离膜的吸湿性

研究了以乙酸纤维素为原料，丙酮为溶煤，用平面铸膜法制备的乙酸纤维素游离膜的吸湿性的特点．结果表明，游离膜的吸湿量和表观膜厚没有关系，仅与致密层厚度相关；增塑剂可增加膜的吸湿性，不同增塑剂对改善膜的吸湿性影响程度不同．     

A facile approach to prepare regenerated cellulose/graphene nanoplatelets nanocomposite using room-temperature ionic liquid

This study presents the preparation of regenerated cellulose (RC)/graphene nanoplatelets (GNPs) nanocomposites via room temperature ionic liquid, 1-ethyl-3-methylimidazolium acetate (EMIMAc) using solution casting method. The thermal stability, gas permeability, water absorption and mechanical properties of the films were studied. The synthesized nanocomposite films were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The T20 decomposition temperature of regenerated cellulose improved with the addition of graphene nanoplatelets up to 5 wt%. The tensile strength and Young's modulus of RC films improved by 34 and 56%, respectively with the addition of 3 wt% GNPs. The nanocomposite films exhibited improved oxygen and carbon dioxide gas barrier properties and water absorption resistance compared to RC. XRD and SEM results showed good interaction between RC and GNPs and well dispersion of graphene nanoplatelets in regenerated cellulose. The FTIR spectra showed that the addition of GNPs in RC did not result in any noticeable change in its chemical structure.