Wood cell wall mimicking for composite films of spruce nanofibrillated cellulose with spruce galactoglucomannan and arabinoglucuronoxylan

Two hemicelluloses (HCs), galactoglucomannan (GGM) and arabinoglucuronoxylan (AGX), and nanofibrillated cellulose (NFC) were isolated from spruce wood and used for the preparation of composite films containing high amounts of cellulose, i.e. 85 and 80 wt% of NFC, respectively. The films were prepared in two ways: (i) by the pre-sorption of HCs on NFC and (ii) by the mixing of components in the usual way. Pre-sorption was applied in an attempt to mimic the carbohydrate biosynthesis pattern during wood cell wall development, where HCs were deposited on the cellulose fibrils prior to lignification taking place. It was assumed that pre-sorption would result in a better film-forming as well as stronger and denser composite films. The mechanical, thermal, structural, moisture sorption and oxygen barrier characteristics of such composite films were tested in order to examine whether the performance of composite films prepared by pre-sorption was better, when compared to the performance of composite films prepared by mixing. The performance of composite films was also tested with respect to the HCs used. All the films showed quite similar barrier and mechanical properties. In general, stiff, strong and quite ductile films were produced. The moisture sorption of the films was comparably low. The oxygen barrier properties of the films were in the range of commercially used poly ethylene vinyl alcohol films. However, the pre-sorption procedure for the preparation of composite films resulted in no additional improvement in the performance of the films compared to the corresponding composite films that had been prepared using the mixing process. Almost certainly, the applied mixing process led to an optimal mixing of components for the film performance achieved. The GGM contributed to a somewhat better film performance than the AGX did. Indications were observed for stronger interactions between the GGM and NFC than that for the AGX and NFC.     

Cellulose film with air barrier and moisture-conducting character fabricated by NMMO

The use of natural polymer to prepare degradable films is a sustainable production concept that can improve resource utilization and reduce the environmental pollution caused by traditional packaging waste or another field. Here, a regenerated cellulose film was prepared through the N-methylmorpholine-N-oxide (NMMO) cellulose system. The most important advantage of the developed film is that it has air barrier and moisture conduction character, because the surface of films is dense and does not allow small molecules like oxygen to pass through, but water molecules can move freely in the film by means of hydrogen bonds. This shows that the cellulose film has applications in textiles, food preservation, medicine and other fields. Significantly, the film has good tensile strength (maximum strength reaches 149.5 MPa) and light transmittance (more than 80% at 600 nm). Moreover, the effect of coagulation bath concentration, temperature and the content of glycerin on film strength was discussed.

     

The hygroscopicity of moisture barrier film coatings

The hygroscopicity of three commercial moisture-barrier film coatings, namely, Eudragit L30 D-55 (methacrylic acid-ethyl acrylate copolymer), Opadry AMB (polyvinyl alcohol based system), and Sepifilm LP 014 (hypromellose, microcrystalline cellulose, and stearic acid based formulation), was investigated using a dynamic vapor sorption apparatus. Moisture uptake by cast films and uncoated and coated tablet cores, which were designed to be hygroscopic, low hygroscopic, and waxy, was measured following exposure to repeat relative humidity (RH) cycles of 0-50-0-50-0%, 0-75-0-75-0%, and 0-90-0-90-0% RH at 25°C. Eudragit cast film exhibited the fastest equilibration but was also the least hygroscopic. Sepifilm had the fastest sorption and took up the greatest mass of water. The rate of uptake for Opadry film was similar to Sepifilm. However, this film continued to sorb moisture for a longer period. When returned to 0% RH it retained moisture in the film showing that it had a high affinity for moisture within the film. The data for the different cores indicated that there was very little benefit in using a moisture barrier film on cores with low hygroscopicity, the mass gain being a sum of that which would be expected to sorb to the film and that which sorbs to the uncoated core. There was, however, some advantage for hygroscopic cores where, even though the barrier coatings allowed substantial water sorption into the core, the extent of this was less and the rate of uptake lower than for the uncoated sample.     

氧化纳米纤维素增强再生纤维素全纤维素复合薄膜的制备及性能

以2,2,6,6-四甲基哌啶-氮-氧化物(TEMPO)氧化松木粉纳米纤维素(TOCNs)为增强相、α-纤维素粉制备再生纤维素(RC)为基体,采用溶胶-凝胶法制备氧化纳米纤维素增强再生纤维素(TOCNs/RC)全纤维素复合薄膜。对不同TOCNs添加量下TOCNs/RC全纤维素复合薄膜的力学性能、光学性能、氧气阻隔性能和热稳定性能进行研究,并通过FTIR、SEM、TEM、XRD和流变仪对TOCNs和TOCNs/RC全纤维素复合薄膜的结构、形貌及纤维素溶液流变性能进行表征。结果表明,TOCNs添加量对TOCNs/RC全纤维素复合薄膜的力学性能有显著影响,当TOCNs添加量(与纤维素基体的质量比)为1.0%时,TOCNs/RC全纤维素复合薄膜的拉伸强度和断裂能分别可达134.3 MPa和21.51 MJ·m?3,具有最佳的综合力学性能;TOCNs/RC全纤维素复合薄膜的透光率随TOCNs添加量的增加而下降,雾度随TOCNs添加量的增加而增大,但仍保持较高的透光率(>85%)和较低的雾度(<14%);TOCNs/RC全纤维素复合薄膜还具有优异的氧气阻隔性,TOCNs添加量为1.6%时,其透氧系数仅为1.47×10?17cm3·cm/cm2·s·Pa。TOCNs/RC全纤维素复合薄膜有优于一般塑料薄膜的拉伸强度和氧气阻隔性,并有可媲美于塑料薄膜的透明度,可作软包装复合材料的强度层和阻隔层,在绿色高性能包装材料领域具有广阔的应用前景。      

Mechanical and permeability properties of biodegradable extruded starch/polycaprolactone films

Barley starch and glycerol were mixed with polycaprolactone (PCL) powder in various combinations and plasticized in a twin-screw extruder. When possible, extrudates were processed into films in a single-screw extruder and subjected to an orientation process with the aim of improving the water durability and mechanical strength of the starch films. The mechanical properties, water vapour and oxygen permeabilities, sorption isotherms and solubility of the processed films were studied. The films containing 20% or more PCL achieved a tensile strength of 20 MPa or higher. Orientation of the film still further improved the tensile strength, and also the water vapour and oxygen barrier properties. With PCL contents of 0–20% the starch/PCL films proved to be excellent oxygen barriers. Increase in PCL content beyond this impaired the oxygen barrier properties, whilst improving the water barrier properties. Copyright © 1998 John Wiley & Sons, Ltd.     

The Hygroscopicity of Moisture Barrier Film Coatings

ABSTRACT

The hygroscopicity of three commercial moisture-barrier film coatings, namely, Eudragit L30 D-55 (methacrylic acid–ethyl acrylate copolymer), Opadry AMB (polyvinyl alcohol based system), and Sepifilm LP 014 (hypromellose, microcrystalline cellulose, and stearic acid based formulation), was investigated using a dynamic vapor sorption apparatus. Moisture uptake by cast films and uncoated and coated tablet cores, which were designed to be hygroscopic, low hygroscopic, and waxy, was measured following exposure to repeat relative humidity (RH) cycles of 0-50-0-50-0%, 0-75-0-75-0%, and 0-90-0-90-0% RH at 25°C. Eudragit cast film exhibited the fastest equilibration but was also the least hygroscopic. Sepifilm had the fastest sorption and took up the greatest mass of water. The rate of uptake for Opadry film was similar to Sepifilm. However, this film continued to sorb moisture for a longer period. When returned to 0% RH it retained moisture in the film showing that it had a high affinity for moisture within the film. The data for the different cores indicated that there was very little benefit in using a moisture barrier film on cores with low hygroscopicity, the mass gain being a sum of that which would be expected to sorb to the film and that which sorbs to the uncoated core. There was, however, some advantage for hygroscopic cores where, even though the barrier coatings allowed substantial water sorption into the core, the extent of this was less and the rate of uptake lower than for the uncoated sample.     

Crosslinking with ammonium zirconium carbonate improves the formation and properties of spruce galactoglucomannan films

Spruce (Picea abies) O-acetyl-galactoglucomannans (GGMs), low-value by-products from the forestry industry were upgraded to sustainable film-forming materials by crosslinking with ammonium zirconium carbonate (AZC). The purpose of crosslinking was to enhance the film formation, reduce the need of polyol plasticizers, and decrease the sensitivity of the film properties to moisture. Tensile testing showed that AZC-crosslinked GGM can be used to prepare strong and stiff films, with tensile strength up to 52 MPa and Young’s modulus of 4.7 GPa. Dynamic mechanical analysis, performed as a function of relative humidity (RH), showed that AZC-crosslinked GGM films retained their stiffness at higher RH than the reference films without AZC. Water vapor sorption and permeability analyses were done to further study the effect of moisture on the film properties, and those showed that the effect of sorbitol as a plasticizer depended greatly on RH. The oxygen permeability of the AZC-crosslinked GGM films was in the range of 4–11 [cm³ μm/(m² day kPa)]. GGM films could offer a bio-based and biodegradable alternative to existing synthetic oxygen barrier materials, on the condition that they are protected from the effects of moisture, e.g., by hydrophobic laminated layers.     

羧甲基纤维素增强膜的制备及性能

目的为了获得一种可用于食品包装的羧甲基纤维素增强膜。方法以羧甲基纤维素(CMC)为成膜基底,甘油为增塑剂,分别将质量分数为1%,3%,5%和10%的纳米纤维素(NCC)添加到CMC中,共混流延制备羧甲基纤维素增强膜(CMC-NCC)。结果 NCC的加入,提高了CMC的力学性能和对水蒸气的阻隔性能,还提高了CMC的热性能。FT-IR分析结果表明,CMC与NCC两者间形成了分子间氢键;XRD分析结果表明,NCC可以改变CMC的结晶排列。当添加质量分数为5%的NCC时,CMC-NCC的拉伸强度比纯CMC膜提高了25.6%,断裂伸长率降低了21.3%,透湿量降低了9%,热稳定性提高了2%,透光率维持在87%以上。结论 CMC增强膜具有力学性能高、阻湿性能好等优点,NCC提高了CMC的成膜品质。     

盐雾试验对PE基真空包装材料阻隔性能的影响

目的获得盐雾环境下PE基包装材料阻隔性能的变化规律。方法考察盐雾试验前后4种PE基包装材料的氧气透过率、水蒸气透过率以及包装膜表面形貌变化情况。结果真空包装技术使聚乙烯包装膜、PE高阻隔包装膜和镀铝高阻隔包装膜等3种包装膜的氧气透过量和水蒸气透过量均有增加,而增强型高阻隔包装膜的氧气透过量和水蒸气透过量均有较大下降。结论 PE基高阻隔包装膜能适应于盐雾环境下装备器材的真空长效包装。     

PEG200增塑改性ACNs/MMT/PHBH纳米复合包装膜

目的 制备聚乙二醇(PEG200)-乙酰化纤维素纳米晶体/蒙脱土/聚3-羟基丁酸酯-co-3-羟基己酸酯(PHBH)纳米复合包装膜,探究PEG200对三元纳米复合材料(ACNs/MMT/PHBH)性能的影响,以获得柔韧性、分散性等性能优良的纳米复合包装膜,增加复合包装膜在包装上的可应用性.方法 通过溶液共混法制备不同比例的PEG200-ACNs/MMT/PHBH纳米复合包装膜,应用扫描电镜、傅里叶红外光谱、偏光显微镜、热重分析、差式扫描量热仪、拉伸测试仪和透氧透湿测试仪,对复合膜的断面形貌、热稳定性、晶体形貌、力学性能和阻隔性能进行分析表征.结果 扫描电镜显示,加入适量的PEG200后,纳米颗粒上具有包覆作用,使得填料与PHBH基质间的相容性得到进一步改善.力学测试结果表明,PEG200的加入使复合包装膜的韧性有一定程度的提高,当PEG200的质量分数为6％时,与未添加PEG200的包装膜相比,其断裂伸长率增加了29.9％.阻隔性能测试结果显示,当PEG200的质量分数为4％时,复合膜的阻隔性能最佳,水蒸气透过率和氧气透过率分别为26.48 g/(m2·d)和28.46 cm3/(m2·d).结论 实验结果表明,加入少量的PEG200能够改善纳米粒子与PHBH之间的相容性,提高ACNs/MMT/PHBH纳米复合材料的韧性和阻氧阻湿性能.     

大豆蛋白添加量与成膜环境对大豆分离蛋白膜的影响

以大豆分离蛋白(SPI)为原料,通过调整SPI和甘油(GLY)的比例来制备不同配方的可食性SPI包装膜。通过观察薄膜色泽、柔软性等表观情况,测定其机械性能(抗拉强度和断裂伸长率)和阻隔性能(阻湿性和阻氧性),并比较了其性能。结果表明:影响SPI膜性能的主要因素为SPI添加量、SPI与增塑剂的质量比、干燥条件;在pH=9条件下,SPI质量为5.66 g,SPI与GLY质量比为6∶1.5,以自然晾干和烘箱干燥结合法进行干燥时,膜的性能最优。     

Reduced water vapour sorption in cellulose nanocomposites with starch matrix

The effects of microfibrillated cellulose nanofibers from wood on the moisture sorption kinetics (30% RH) of glycerol plasticized and pure high-amylopectin starch films were studied. The presence of a nanofiber network (70 wt% cellulose nanofibers) reduced the moisture uptake to half the value of the pure plasticized starch film. The swelling yielded a moisture concentration-dependent diffusivity. Quite surprisingly, the moisture diffusivity decreased rapidly with increasing nanofiber content and the diffusivity of the neat cellulose network was, in relative terms, very low. It was possible to describe the strong decrease in zero-concentration diffusivity with increasing cellulose nanofiber/matrix ratio, simply by assuming only geometrical blocking using the model due to Aris. The adjusted model parameters suggested a “simplified” composite structure with dense nanofiber layers oriented in the plane of the film. Still, also constraining effects on swelling from the high modulus/hydrogen bonding cellulose network and reduced amylopectin molecular mobility due to strong starch–cellulose molecular interactions were suggested to contribute to the reductions in moisture diffusivity.     

绿茶提取物对聚乙烯醇/微晶纤维素薄膜性能的影响

为了研究绿茶提取物不同含量对聚乙烯醇/微晶纤维素薄膜性能的影响,通过流延法制备得到绿茶提取物不同含量的聚乙烯醇/微晶纤维素薄膜,测定分析不同含量绿茶提取物对薄膜的颜色、透明性、力学性能、疏水性能和气体阻隔性能的影响。结果表明:随着绿茶提取物含量的增加,薄膜亮度稍有变暗,颜色趋于红色、黄色;透明性显著降低;薄膜抗拉强度显著增加,断裂伸长率显著降低;薄膜的疏水性能提高,薄膜的溶胀率、持水率降低;薄膜的水蒸气透过率和氧气透过率降低。因此,绿茶提取物的加入,提高了薄膜的力学性能、疏水性和气体阻隔性,为薄膜在食品包装中的应用提供了基础。     

Influence of tartaric acid on the bioadhesion and mechanical properties of hot-melt extruded hydroxypropyl cellulose films for the human nail

The objective of this study was to investigate the influence of tartaric acid (TTA) on the bioadhesive, moisture sorption, and mechanical properties of hot-melt-extruded (HME) hydroxypropyl cellulose (HPC) films containing polymer additives. Two Klucel® EF and LF batches (HPC, MW: 80000 and 95000, respectively) containing the model antifungal drug ketoconazole (one batch of each MW with and without TTA 4%) were prepared into films by HME using a Killion extruder (Model KLB-100). The bioadhesive properties of the HPC films, with and without TTA, were investigated ex vivo on the human nails. The parameters measured were work of adhesion and peak adhesion force (PAF). A statistically significant increase in both the area under the curve (AUC) and PAF was seen for the HME films containing TTA than those without TTA. Moisture content of hot-melt extruded HPC films was determined using thermogravimetric analysis (TGA). TGA data collected at the two-week interval (25°C/60% RH), measured higher moisture content for the TTA-containing films than those without TTA. Tensile strength and percent elongation were determined utilizing a TA.XT2i Texture Analyzer® equipped with a 50-kg load cell, TA-96 grips, and Texture Expert™ software. TTA functioned as an effective plasticizer, increasing percent elongation and decreasing tensile strength of the HPC films. TTA could potentially be a candidate for transnail applications in film devices prepared by hot-melt extrusion technology.     

油茶果壳氧化纳米纤维素-海藻酸钠复合薄膜的 制备及性能

以油茶果壳为研究对象,利用碱煮漂白法提取纤维素,并利用2, 2, 6, 6-四甲基哌啶-1-氧自由基（TEMPO）氧化法,制备TEMPO氧化纳米纤维素（TOCNs）,经离子交联法建立TEMPO氧化纳米纤维素与海藻酸钠（SA）的半互穿交联网络,制得综合性能优异的复合薄膜。对复合薄膜进行了结构表征,力学性能测试,热稳定性和阻氧性能测试。实验结果表明： TOCN/SA薄膜表面平整,有致密的内部层状结构,适量SA和TOCNs具有较好的相容性。当SA的掺杂质量分数达到42%时,TOCN/SA薄膜的断后伸长率较TOCN薄膜增长138.6%,氧气透过率降低15.55%,碳残余量较TOCN薄膜提高21.4%。因此,油茶果壳氧化纳米纤维素TOCN/SA复合薄膜,具有良好的力学性能和热稳定性,同时保持了较好的阻氧性能。     

The relation between the moisture vapour permeability and moisture vapour adsorption of regenerated cellulose films

Hydrophilic, regenerated cellulose films are characterized by certain adsorption properties. These investigations were aimed at determining to what extent the moisture content of a film might decide its barrier capacity against water vapour. The experimental materials were an unlacquered regenerated cellulose film and one varnished on both the sides with nitrocellulose lacquer. The investigations allowed us to propose some models that formally describe the adsorption process of water vapour through films at different values of ambient relative humidity. In addition, we determined the functional relation between the water vapour permeability of the films under investigation and their moisture contents and equilibrium ambient relative humidity values. Copyright © 1999 John Wiley & Sons, Ltd.     

Binderless all-cellulose fibreboard from microfibrillated lignocellulosic natural fibres

Fully biobased all-cellulose fibreboards are produced without the use of additional bonding agents such as polymer resins or binders as in the case of e.g. medium density fibreboard (MDF) or natural fibre reinforced plastic (NFRP). These materials make use of the self-binding capability of cellulose, exploiting the enhanced hydrogen bonded network present in micro- and nanofibrillated cellulose, resulting in good mechanical performance. After the optimisation of refinement, drying and hot-pressing conditions, binder-free panels from microfibrillated flax fibres with excellent mechanical properties of around 17 GPa and 120 MPa for flexural modulus and strength, and relatively low water sorption are achieved, making these materials competitive with conventional cellulose based composite materials. The work shows the potential of creating all-cellulose engineering materials using only the intrinsic bonding capacity of microfibrillated lignocellulose, potentially leading to environmentally friendly panel board materials, which are entirely based on renewable resources, recyclable and biodegradable.     

Influence of Tartaric Acid on the Bioadhesion and Mechanical Properties of Hot-Melt Extruded Hydroxypropyl Cellulose Films for the Human Nail

ABSTRACT

The objective of this study was to investigate the influence of tartaric acid (TTA) on the bioadhesive, moisture sorption, and mechanical properties of hot–melt-extruded (HME) hydroxypropyl cellulose (HPC) films containing polymer additives. Two Klucel® EF and LF batches (HPC, MW: 80000 and 95000, respectively) containing the model antifungal drug ketoconazole (one batch of each MW with and without TTA 4%) were prepared into films by HME using a Killion extruder (Model KLB-100). The bioadhesive properties of the HPC films, with and without TTA, were investigated ex vivo on the human nails. The parameters measured were work of adhesion and peak adhesion force (PAF). A statistically significant increase in both the area under the curve (AUC) and PAF was seen for the HME films containing TTA than those without TTA. Moisture content of hot-melt extruded HPC films was determined using thermogravimetric analysis (TGA). TGA data collected at the two-week interval (25°C/60% RH), measured higher moisture content for the TTA-containing films than those without TTA. Tensile strength and percent elongation were determined utilizing a TA.XT2i Texture Analyzer® equipped with a 50-kg load cell, TA-96 grips, and Texture Expert? software. TTA functioned as an effective plasticizer, increasing percent elongation and decreasing tensile strength of the HPC films. TTA could potentially be a candidate for transnail applications in film devices prepared by hot-melt extrusion technology.     

Technology and applications of edible protective films

Edible films or coatings have provided an interesting and often essential complementary means for controlling the quality and stability of numerous food products. There are many potential uses of edible films (e.g. wrapping various products, individual protection of dried fruits, meat and fish, control of internal moisture transfer in pizzas, pies, etc.) which are based on the films properties (e.g. organoleptic, mechanical, gas and solute barrier). Polysaccharide (cellulose, starch, dextrin, vegetable and other gums, etc) and protein (gelatin, gluten, casein, etc) based films have suitable mechanical and organoleptic properties, while wax (beeswax, carnauba wax, etc) and lipid or lipid derivative films have enhanced water vapour barrier properties. The film-forming technology, solvent characteristics, plasticizing agents, temperature effects, solvent evaporation rate, coating operation and usage conditions of the film (relative humidity, temperature) can also substantially modify the ultimate properties of the film.     

Hot-Melt Coating: Water Sorption Behavior of Excipient Films

Hot-melt coating allows encapsulation of water-labile, drug-laden substrates to form a barrier that resists moisture ingress. To understand the interaction of water with excipients that can form moisture-protective coatings, sorption behavior of films of lipidic (glyceryl behenate) and polymeric (polyvinyl alcohol) coating excipients was investigated. A simple and rapid method using a new, fully automated instrumental technique to investigate the sorption/desorption behavior of excipient films is reported. Further, the influence of temperature and film thickness on the sorption behavior of films is examined. Both excipient films displayed sorption isotherms that were classified as type III and demonstrated hysteresis during desorption. The sorption data for both films did not follow the Langmuir model, and the BET model could only be used restrictively. The GAB model fitted the sorption data at all conditions and over the entire range of water activity studied. The ability of the Young and Nelson model to explain the hysteresis behavior, from analytical and mechanistic perspectives, is evaluated. Temperature and film thickness were found to profoundly influence the nature of moisture interaction and distribution of moisture in the excipient films. An Arrhenius-type relationship was observed between equilibrium moisture content of excipient films and temperature at constant water activity.