包装材料对肉类食品胀袋问题的影响与分析

目的 比较分析不同种类包装材料的性能差异对所包装肉类食品胀袋问题的影响。方法 以常见的用于包装烧鸡的PA/Al/CPP、BOPA/LDPE,包装猪蹄的PET/PA/CPP、PET/PA/Al/CPP,包装肉肠的PVDC共挤膜、BOPP/PVDC/PE等6种材料为试验样品,分别测试其揉搓前后氧气透过量、拉伸性能、抗穿刺性能、热封强度、密封性能。结果 样品阻隔性由高到低依次为PET/PA/Al/CPP、PA/Al/CPP、PVDC共挤膜、BOPP/PVDC/PE、PET/PA/CPP、BOPA/LDPE;揉搓后PET/PA/Al/CPP阻隔性仍较高,PA/Al/CPP耐揉搓性差,出现贯穿性针孔,揉搓前后BOPA/LDPE、PET/PA/CPP的阻隔性相差不大;BOPP/PVDC/PE拉伸性能较差,横向断裂伸长率仅为28.4%,且热封强度低,其余样品的拉伸性能、抗穿刺性能、热封强度均较好;PA/Al/CPP,BOPP/PVDC/PE成品包装分别在袋体折皱处、袋体与热封口处漏气,其余样品均未漏气。结论 耐揉搓性差、拉伸性能差及热封强度低分别是烧鸡PA/Al/CPP包装、肉肠BOPP/PVDC/PE包装发生胀袋的主要原因;阻氧性偏低易导致由BOPA/LDPE,PET/PA/CPP,PVDC 5层共挤膜包装的烧鸡、猪蹄、肉肠在长时间存储时缓慢胀袋。上述样品存在的问题主要与材质结构、铝箔层质量、材料生产及热封工艺有关。     

PET/PE复合材料最佳热封工艺参数研究

PET/PE复合薄膜广泛应用于食品和药品包装,但在生产过程中存在热封质量不稳定的问题,为了探索PET/PE复合薄膜热封质量的影响因素,采用热封机对复合材料进行热封,并用拉伸实验对热封强度进行测试,比较分析了热封方向、热封温度、热封速度对热封质量的影响作用,总结得出了PET/PE复合薄膜的最佳热封工艺参数。     

具有高界面压应力的高分子共混物Ⅰ.制备和拉伸性能

考察了高界面压应力对不相容聚对苯二甲酸乙二醇酯(PET)/聚乙烯(PE)和聚碳酸酯(PC)/PE共混物拉伸性能的影响.高界面压应力是共混物低温成型(PE的成型温度)时,分散相与基体从加工温度冷却到室温过程中基体的收缩比分散相粒子大产生的.尽管PET/PE和PC/PE共混物极不相容,但拉伸强度和模量随着PET和PC含量增加而增加.PET与PC含量相同时,PC/PE的拉伸强度和模量高于PET/PE的.采用Takayanangi方程计算共混物的拉伸模量时,具有高界面压应力的PC/PE共混物的拉伸强度高于界面有良好粘结的共混物的理论值,表明在不添加增容剂时,可通过控制加工条件改善共混物界面相互作用,提高共混材料的性能.     

热拉伸比对PET/ PE 原位微纤化复合材料形态和拉伸性能的影响

采用熔融挤出2热拉伸2淬冷方法制备了聚对苯二甲酸乙二醇酯( PET) / 聚乙烯( PE) 原位微纤化复合材料。固定体系组成( PET/ PE 为15/ 85), 热拉伸比增加, PET 粒子相继从球状转变成椭球状、棒状和纤维状; 除了最小粒径保持基本不变外, 最大和平均粒径均逐渐减小。微纤化复合材料在PE 的加工温度下成型时, 纤维能够良好地保持在体系中, 但在PET 的加工温度下成型时, 纤维重新熔融, 形成球状粒子。复合材料的拉伸模量和拉伸强度随拉伸比增加显著增加, 表明微纤化对材料具有良好的增强效果; 而断裂伸长率随热拉伸比增加剧烈下降, 产生明显的韧-脆转变。比基本断裂功( we ) 先随热拉伸比( HSR) 增加而增加, 热拉伸比为19117 左右时达到最大值, 继续增加热拉伸比, we 降低。      

塑料包装袋热合强度的失效模式分析

热合强度是考核复合塑料包装袋热合面封口牢固度的一个重要指标,检测标准中并没有说明测量热合强度时的失效模式。根据QB/T 2358—1998《塑料薄膜包装袋热合强度试验方法》,对PET/Al/PA/RCPP结构、OPP/VMPET/PE结构、PET/RCPP结构、PET/Al/PA/RCPP结构薄膜和阴阳镀铝复合薄膜几种不同材质塑料包装袋进行了热合强度试验,总结得出了5种失效模式,即热封层剥离、热封边缘断裂、薄膜断裂、薄膜分层、先分离后撕裂,结合测量曲线图与失效模式图,分析了各失效模式的形成原因,以便有效指导与改进塑料包装袋的生产工艺。     

双向拉伸聚对苯二甲酸乙二醇酯/聚己二酰间苯二胺的形态结构与阻隔及力学性能

以聚对苯二甲酸乙二醇酯(PET)和聚己二酰间苯二胺(MXD6)为原料,通过熔融共混和同步双向拉伸的方法制备了双向拉伸PET/MXD6复合材料。通过扫描电子显微镜、气体渗透试验、差示扫描量热仪及力学性能测试研究了双向拉伸PET/MXD6复合材料的形态结构及其对复合材料气体阻隔性能、力学性能及结晶性能的影响。研究结果表明,通过同步双向拉伸,使MXD6在PET基体中的分散相形态由零维球形变为高长径比的二维片状,这些形态使得双向拉伸复合材料的气体阻隔性能与力学性能大幅提高,其中质量分数20%的PET/MXD6复合薄膜材料在拉伸倍率为3×3时,较纯PET相比提升了2.3倍。与此同时,断裂伸长率与拉伸强度也大幅提高,最大增幅分别达到10.6倍和3.1倍。     

化学助剂对淀粉/EVA复合发泡材料力学性能的影响

在以淀粉和乙烯-醋酸乙烯酯(EVA)为主料制备复合发泡材料的过程中,原料中各种化学助剂对复合发泡材料的力学性能影响显著。重点研究了发泡剂(NaHCO3)、增塑剂(甘油)、交联剂(DCP)3种化学助剂的用量对淀粉/EVA复合发泡材料拉伸强度和断裂伸长率的影响,结果表明:NaHCO3存在一优化值,使得材料拉伸强度达到最小值,同时断裂伸长率达到最大值;复合发泡材料的拉伸强度随着甘油含量的增加而逐渐降低,断裂伸长率则呈现相反的趋势;当DCP含量在0.6%~0.9%时,拉伸强度和断裂伸长率都达到最大值。     

加载速率对低密度聚乙烯薄膜拉伸性能的影响

研究了在不同加载速率下低密度聚乙烯薄膜横向、纵向拉伸强度和断裂伸长率的变化规律.实验结果表明,其横向拉伸强度和断裂伸长率大于纵向拉伸强度和断裂伸长率;拉伸速率对拉伸强度和断裂伸长率没有显著影响.     

液体农药软包装的研究现状及展望

液体农药因含有毒性较大且腐蚀性较强的甲苯、二甲苯等有机溶剂,其软包装材料应具备较强的耐腐蚀性能和阻隔性能。目前国内市场上液体农药软包装常用的材料主要有PET/Al/CPP(或PE)复合膜、PET/VMPET/CPP(或PE)复合膜、含PA或EVOH的PP,PE多层共挤膜、PET/PVDC(或EVOH)/CPP(或PE)透明复合膜等,常用的胶黏剂为聚氨酯胶黏剂。液体农药包装废弃物的处理一般采取随意丢弃和集中填埋焚烧2种方式,均对环境及人类健康危害较大,必须采取相应的措施以降低其危害。液体农药软包装必须朝绿色环保方向发展,研发并推广可降解材料与水溶性膜。     

聚乙烯醇/海藻酸钠复合膜性能的正交优化

目的提高海藻酸钠/聚乙烯醇复合膜的断裂伸长率。方法利用溶液流延制备系列复合薄膜,采用正交设计方法研究海藻酸钠和聚乙烯醇的质量比、甘油用量和Zn O用量等3个因素对复合膜拉伸强度和断裂伸长率及其他性能的影响。结果甘油用量显著影响海藻酸钠/聚乙烯醇复合膜的断裂伸长率,其影响程度高于其他2个因素;Zn O和甘油的加入使得复合膜的拉伸强度显著降低。结论采用正交设计方法有利于研究各因素对复合膜物理性能的影响,为进一步的复合膜研究提供参考。     

SiOx/PET复合薄膜的力学性能及阻隔性能

目的基于氧化硅(SiO_x)镀层优异的性能,研究不同厚度的SiO_x层对SiO_x/PET复合薄膜力学性能和阻隔性能的影响,以期得到性能较优的SiO_x/PET复合薄膜。方法以自制的聚对苯二甲酸乙二醇酯(PET)薄膜为基材,采用等离子体增强化学气相沉积法沉积得到SiO_x层厚度分别为40,150,230,320 nm的SiO_x/PET复合薄膜,并进行傅里叶变换红外线光谱分析、力学性能和阻隔性能测试,以及薄膜表观形貌分析。结果沉积SiO_x层后,SiO_x/PET复合薄膜拉伸强度和断裂伸长率随SiO_x层厚度的增大先增大后减小,氧气透过率和水蒸气透过率则出现明显衰减而后逐渐平缓的趋势。SiO_x层厚度达150~230 nm时,复合薄膜的力学性能和阻隔性能表现较优,拉伸强度、断裂伸长率、氧气透过率以及水蒸气透过率分别提高了约25.0%,20.9%,79.3%,77.3%。结论适宜厚度的SiO_x层可以使得SiO_x/PET复合薄膜同时具备较优的力学性能和阻隔性能。     

植物油类调味品防漏油包装材料及措施探索

目的 寻找合适的植物油调味品包装材料、试验配件,以获取热封压力范围,解决植物油调味品行业实际生产中产品包装漏油问题。方法 采用PA15/PE62,PA15/PE65,PA15/PE55,PET/PET镀铝/PE,PET/Al/PE,PET12/PE38等7种包装材料,在使用自动制袋式填充包装机实际生产环境下进行50,150,300 g等3种规格的清油类底料灌装,并施加30 kg重物进行90 d储存试验,每隔15 d观察包装的封口质量;添加热封压力调节配件,在实际生产中可间接指示热封压力范围,进而探索不同材质的热封压力调节范围。结果 在进行了90 d压力储存后,发现3种规格的样品包装材料漏油率在0~17.95%之间,其中PA15/PE62在50,150,300 g等3种规格下的漏油率均为0,可见该材质在现有生产条件下能够有效缓解漏油现象;该压力配件效果较好,得出2种卷料的热封调节配件调节圈数集中在7.4~6.25圈,7.4~5.75圈。结论 PA15/PE65能有效缓解实际生产中的热封部位断根现象、漏油现象;该压力配件的使用便于生产企业找寻热封压力与热封温度的平衡点,进而缓解漏油现象。     

Effect of high‐pressure processing on the mechanical and barrier properties of selected packagings

This investigation focuses on the effect of high‐pressure processing (HPP) on possible changes of the mechanical properties and of the water vapour permeability of seven selected packaging materials. NOD 259 (PA‐PE), BB4L (Cryovac‐Grace packaging), PET/BOA/PE, PET/PVDC/PE, PA/SY, LDPE and EVA/PE were investigated (PET, polyester; PE, polyethylene; SY, surlyn; LDPE, low‐density polyethylene; EVA, polyethylene–vinyl acetate co‐polymer; BOA, biaxially oriented polyamide). These packaging materials were selected because of their interest to the food industry. All had an internal film of PE for food use. High‐pressure tests were realized at 10°C for 10 min at pressures of 200, 400 and 600 MPa, with water as a food‐simulating fluid. The depressurization rate was either rapid (pressure drop in <10s) or slow (20 MPa/min). Permeability to water vapour was realized using the NFF H 00 030–ASTM E96‐90 standard. Mechanical tests were carried out with a tensile testing machine (Lloyd LR5K), according to the NF 54‐102 standard. Maximal stress, rupture stress and strain at rupture were evaluated with non‐treated and treated samples. Obtained results showed that HPP minimally affects the mechanical strength of packaging material. The depressurization rate did not have any significant influence in our conditions. The barrier properties to water vapour were not significantly affected and were even slightly enhanced for LDPE, which is a packaging material commonly used for HPP applications and at least as a food contact material. Copyright © 2006 John Wiley & Sons, Ltd.     

Effect of UV‐Radiation on the Packaging‐Related Properties of Whey Protein Isolate Based Films and Coatings

The high oxygen barrier properties of whey protein based films and coatings means these materials are of great interest to the food and packaging industry. However, these materials have poor mechanical properties such as the tensile strength, Young's modulus and elongation at break. Up until now, the influence of ultraviolet (UV) radiation on whey protein films has not been reported in the literature. This study thus investigates the influence of UV‐radiation on the properties of whey protein based films. UV‐irradiated films showed increased tensile strength and a yellowing that was dependent on the radiation time. After irradiation, the films showed no significant change in the barrier properties, Young's modulus or elongation at break. In addition, a protein solubility study was undertaken to characterize and quantify changes in structure‐property relationships. The significant decrease in protein solubility in buffer systems which break disulfide and non‐covalent bonds indicates that additional molecular interactions arise with increasing radiation dose. This study provides new data for researchers and material developers to tailor the characteristics of whey protein based films according to their intended application and processing. Copyright © 2015 John Wiley & Sons, Ltd.     

纺丝液合成因素对木材液化物炭纤维原丝性能的影响

利用木材苯酚液化物合成纺丝液, 熔融纺丝制成新的炭纤维原丝, 研究了纺丝液合成因素对原丝性能的影响。试验结果表明: 增加合成纺丝液时液化原料中的苯酚/木材比(液固比), 则原丝的力学性能提高明显, 其中液固比由3增加至4时, 原丝拉伸强度增加了近9倍; 合成剂用量的增加却导致原丝力学性能的降低, 当合成剂用量为6%时, 原丝的拉伸强度和拉伸模量降幅较明显, 而断裂伸长率的最大降幅却出现在合成剂用量为4%时; 原丝的拉伸强度和拉伸模量随合成温度的升高而增加, 但增幅较小, 断裂伸长率随合成温度的升高却呈下降趋势, 且从110℃升高到115℃时断裂伸长率降幅较大; 原丝的力学性能随合成纺丝液升温时间的增加而先升高后降低, 升温时间为40min时制备的炭纤维原丝的力学性能最优。      

聚对苯二甲酸乙二醇酯/锡氟磷酸盐玻璃复合材料原位成纤对聚丙烯的增强效果

采用低玻璃化转变温度的锡氟磷酸盐玻璃(Pglass)改性聚对苯二甲酸乙二醇酯(PET),制备低黏度高模量的PET基复合材料(PET/Pglass);以PET/Pglass或PET为成纤相,聚丙烯为基体,利用实验室自主设计的多级拉伸挤出装置,制得原位成纤增强聚丙烯复合材料,并研究成纤相形态及其对复合材料力学性能的影响。结果表明,与PET相比,PET/Pglass在多级拉伸挤出过程中原位成纤更容易,纤维长径比更大,分散更均匀,从而进一步提高聚丙烯的拉伸强度和模量,而且能保持聚丙烯较高的断裂伸长率,表明具有低黏高模的PET/Pglass对聚丙烯的原位成纤增强效果更显著。     

Morphology-tensile behavior relationship in injection molded poly(ethylene terephthalate)/polyethylene and polycarbonate/polyethylene blends (II) Part II Tensile behavior

The tensile behavior of injection molded poly(ethylene terephthalate) (PET)/polyethylene (PE) and polycarbonate (PC)/PE blends was investigated. For the same blend, due to the difference in the elongated dispersed particle concentration, the specimens molded at higher injection speed had slightly higher tensile strength and modulus than those molded at lower speed. Moreover, the reinforcement effect of PC to PE matrix was more noticeable than PET to PE. For the stress-strain behavior, while the PET/PE blend behaved like a common injection-molded immiscible blend the PC/PE blend unusually underwent twice yielding regardless of the cross head speed. For the PET/PE blend, obvious debonding between the dispersed PET particles and the matrix PE occurred upon elongation, resulting in large grooves and voids behind the particles. The PET particles experienced slight plastic deformation from spheres to ellipsoids. The stress whitening first appeared in the necking zone then extended along cold drawing zone. For the PC/PE blend, the PC particles in the core layer experienced considerable plastic deformation throughout the tensile test. Consequently, most of PC particles in the fractured specimen were deformed into fibers. Owing to comparatively high amount of injection-induced fibers that distributed or transferred the external stress, the specimen of PC/PE blend first deformed evenly in the entire tested zone, characterized by stress whitening in the entire specimen. Then after the first yielding, the stress decreased slowly while the elongation continued. When the elongation reached a certain point, the fibers in the sub-skin layer could no longer endure the external stress, and accordingly the second yield took place. Additionally, the fibrillation of the spherical PC particles in the core layer appeared right after the second yielding point.