木质素/PVA发泡材料的制备及性能表征

目的探究木质素/PVA发泡材料的制备工艺及性能优化。方法采用控制单一变量和正交试验法对木质素、PVA溶液质量分数、甲醛、硫酸的制备工艺进行探索及优化。结果单因素试验结果显示,木质素/PVA发泡材料的最佳工艺水平,PVA溶液的质量分数为9%,木质素用量为30%(文中所提用量均表示相对于PVA的质量,下同),甲醛用量为24%,硫酸用量为39%。正交试验结果显示,发泡材料的制备工艺最优组合,PVA溶液的质量分数为9%,木质素用量为20%,甲醛用量为40%,硫酸用量为47%。FTIR结果显示,木质素与PVA在适宜的条件下发生缩醛交联反应生成木质素/PVA发泡材料,但反应程度低,以在木质素苯环5位发生的取代反应为主。SEM显示,在不考虑各因素的相互影响下,各单因素木质素用量为30%,PVA溶液的质量分数为9%,甲醛用量为24%,硫酸用量为47%时所制备的发泡材料形成了较规则、均匀分布的泡孔或数目较多的孔隙结构。结论各单因素用量对木质素/PVA发泡材料的性能有很大影响,4个因素对发泡材料性能影响的主次排序为木质素用量PVA溶液的质量分数硫酸用量甲醛用量。     

乙二醛交联对明胶/PVA可生物降解复合膜性能的影响

采用流延成型法制备明胶/聚乙烯醇(Gel/PVA)复合膜,并以乙二醛为交联剂通过溶液交联法制备乙二醛交联的Gel/PVA复合膜,采用红外光谱(FTIR)、X-射线衍射(XRD)、差示扫描量热(DSC)、热重(TG)等表征交联前后复合膜的结构与性能,研究了交联剂用量对Gel/PVA复合膜力学性能及溶解性能的影响。结果表明,随着乙二醛用量的增加,Gel/PVA复合膜的拉伸强度呈先增加后逐渐降低的趋势,而断裂伸长率和溶解率则逐渐降低;乙二醛交联可提高复合膜的熔融温度及热稳定性;乙二醛交联显著影响Gel/PVA复合膜中分子间的氢键和化学结构。     

新型磷酸单酯PVA聚阴离子电解质膜材料的合成及性能

采用磷酸和聚乙烯醇(PVA)在尿素存在下发生单酯化反应,合成了一种新型聚阴离子电解质磷酸单酯PVA(PMPVA).考察了反应时间、反应温度、磷酸用量、尿素用量对取代度的影响.利用傅立叶变换红外光谱(FT-IR)、扫描电镜(SEM)对PMPVA的结构进行了表征,PMPVA的导电和耐热性随取代度的增大而提高.将PMPVA及PMPVA/季铵化聚阳离子PVA(QAPVA)复合物制备的渗透汽化复合膜,用于乙醇/水体系进行渗透汽化分离.PMPVA对水的分离因子α为637,渗透通量J为3903g/(m2·h);PMPVA/QAPVA复合物膜对水的分离因子α为1890、渗透通量J为520g/(m2·h).     

纳米TiO_2改性淀粉复合薄膜的制备及其性能研究

在醋酸酯淀粉(PMS)/聚乙烯醇(PVA)共混系统中引入超声分散的纳米TiO_2悬浮液,以山梨醇(SOR)和尿素为塑化剂采用流延工艺制备了纳米TiO_2改性复合膜,研究了纳米TiO_2的加入量以及SOR和尿素的配比对复合膜性能的影响,用红外光谱和扫描电镜对复合膜的结构和形貌进行了表征。结果表明适当的纳米TiO_2的量以及SOR和尿素的配比可有效地改善复合膜的力学性能和耐水性能,加入0.003g纳米TiO_2可将膜的拉伸强度提高71.1%,SOR和尿素质量比为1∶3时,膜的拉伸强度为39.40MPa,吸水率降至73.58%。     

木质素/PVA发泡材料改性研究

目的探究甘油用量对木质素/PVA发泡材料性能的影响。方法采用水浴加热方法对PVA和木质素进行溶解处理,再加入不同量的甘油,以不加甘油的空白样为对照,测试及表征其性能。结果随着甘油用量的增加,发泡材料的拉伸强度先增加后降低,甘油用量为8%时材料的拉伸强度达到最大,为1.26 MPa;断裂伸长率逐渐增大,从最初的37%增大到167%;表观密度先下降后上升,最低为0.278g/cm3;吸水率逐渐降低,最低达到15.22%。SEM测试表明,甘油的加入改善了发泡材料的空隙结构,但加入过多的甘油会破坏泡孔结构。TGA结果表明,随着甘油用量的增加,所得复合材料的热稳定性降低,热分解起始温度和分解最大速率温度都逐渐降低。结论甘油对木质素/PVA发泡材料的性能影响较大,加入适量的甘油对材料的力学性能、泡孔结构和热稳定性都有很强的促进作用。     

氯化镁/甘油改性羧甲基淀粉/聚乙烯醇共混材料的结构与性能

为获得改性淀粉/聚乙烯醇(PVA)共混材料的结构与性能特征,以氯化镁/甘油为复配改性剂,采用溶液成膜方法制备了羧甲基淀粉(CMS)/PVA,研究了CMS/PVA复合膜的红外吸收特性、结晶性能、微观形貌、热性能、力学性能及生物降解性。研究结果表明,氯化镁和甘油可与CMS/PVA产生电子相互作用和氢键作用,阻碍CMS/PVA分子链的规整排列,提高羧甲基淀粉与PVA的相容性,降低CMS/PVA的结晶度和热稳定性。氯化镁/甘油复配改性剂对CMS/PVA的力学性能影响显著,可使CMS/PVA断裂伸长率和拉伸强度提高。氯化镁/甘油可促进CMS/PVA的降解,增加氯化镁/甘油复配改性剂中氯化镁的含量可提高复合膜的降解率。     

载银-四环素-有机膦酸锆/聚乙烯醇复合膜的制备及表征

以亚磷酸、甘氨酸、甲醛为主要原料，在酸性环境下合成有机膦酸，再与氧氯化锆反应生成含有羧基的有机膦酸锆，进一步与四环素和硝酸银反应生成载Ag-四环素-有机磷酸锆(Ag-T-ZGDP)。采用流延法制备了载Ag-四环素-有机磷酸锆/聚乙烯醇(Ag-T-ZGDP/PVA)复合膜，并利用红外光谱(FT-IR)、X射线衍射(XRD)、透射电镜(TEM)、扫描电镜(SEM)等手段研究了该复合膜的结构与性能。结果表明：随着Ag-T-ZGDP含量的增加，Ag-T-ZGDP/PVA复合膜的力学性能增强，当Ag-T-ZGDP与PVA质量比为2.0%时，力学性能达到最佳；且该比例的Ag-T-ZGDP/PVA复合膜中Ag离子缓慢释放，对大肠杆菌有一定的抑菌效果。XRD、TEM分析表明：纳米Ag被均匀负载在Ag-T-ZGDP的片层结构中；SEM分析表明：Ag-T-ZGDP均匀分散于Ag-T-ZGDP/PVA复合膜中，表现出良好的相容性，随着Ag-T-ZGDP含量的增加，断层逐渐变成光滑平面，在Ag-T-ZGDP与PVA质量比为2.0%时，断层最光滑。     

载Ag改性桑枝韧皮纤维素/聚乙烯醇复合膜的制备及表征

采用流延法制备了载Ag改性桑枝韧皮纤维素/聚乙烯醇（Ag-T-CMC/PVA）复合膜,并利用XRD、SEM、DSC等分析测试方法研究了该复合膜的结构和性能。结果表明:随着Ag-T-CMC含量增加,Ag-T-CMC/PVA复合膜的力学性能、耐水性及抗菌性能均有提高。当Ag-T-CMC与PVA质量比为2%时,力学性能达到最佳,拉伸强度提高了3.4%。SEM分析表明:Ag-T-CMC均匀分散于Ag-T-CMC/PVA复合膜中,表现出良好的相容性;随着Ag-T-CMC含量的增加,断层逐渐变得光滑平面,在Ag-T-CMC与PVA质量比为2%时,断层最光滑。吸水性能测试表明:Ag-T-CMC能明显降低Ag-T-CMC/PVA复合膜的吸水性。抑菌性能测试表明:Ag-T-CMC/PVA复合膜对大肠杆菌和金黄色葡萄球菌有一定的抑菌效果,且随着Ag-T-CMC含量的增大,抑菌圈直径变大,抑菌效果增强。      

交联羧甲基玉米淀粉／PVA复合膜制备工艺的研究

以玉米淀粉为原料,采用先醚化后交联改性工艺合成了交联羧甲基玉米淀粉(CCMS).通过改性淀粉与聚乙烯醇(PVA)溶液共混反应,并辅以增塑剂、增强荆、交联剂及疏水化改性剂等加工助荆制备了性能优异的CCMS/PvA复合膜.研究了复合膜制备过程中的影响因素及其对薄膜耐水性能、透光性能和力学性能的影响.结果表明,当交联羧甲基玉米淀粉与PVA的质量比为7:3,甘油用量为10%(质量分数),复合交联剂用量3.3%(质量分数),疏水化改性荆聚酰胺多胺环氧氯丙烷树脂(PPE)用量为1.5%(质量分数),溶液pH为10,反应温度88℃,反应时间35min时,淀粉膜的拉伸强度为40.5MPa,断裂伸长率为311%,透光率为82%,吸水率最小为3.6%(质量分数).     

壳聚糖/聚乙烯醇/CeO2三元复合膜的制备及其性能研究

CeO2经阴离子表面改性剂SDS表面改性后,采用溶液共混法制备了壳聚糖/聚乙烯醇/CeO2复合膜,采用扫描电子显微镜(SEM)对复合膜的表面形貌进行表征;傅里叶红外光谱(FTIR)研究吸附前后复合膜上基团的变化;热重分析仪(TG)分析复合膜的热稳定性;测试复合膜的力学性能及溶胀率并进行分析,探讨CeO2和PVA的加入对壳聚糖膜力学性能和吸水率的影响;采用二苯碳酰二肼分光光度法研究时间对Cr(Ⅵ)吸附的影响.实验结果表明:改性后的CeO2在复合膜中分散均匀,与复合膜的相容性较好.随着CeO2的增加,复合膜的热稳定性提高,断裂强力和断裂伸长率增大,溶胀率下降,相比较纯壳聚糖膜,断裂强力最大可提高47.4％,溶胀率最大可下降53.9％.复合膜对Cr(Ⅵ)的平衡吸附量可以达到11.2mg/g.     

Effect of polyethylene glycol on the mechanical property, microstructure, thermal stability, and flame resistance of phenol–urea–formaldehyde foams

In this study, polyethylene glycol (PEG) was added to phenol–urea–formaldehyde foam to improve its toughness, and the effects of PEG, with different molecular weights and dosages, on the mechanical property, microstructure, thermal stability, and flame resistance of phenol–urea–formaldehyde foam were studied. The addition of PEG significantly increased the toughness and impact strength and decreased the pulverization rate of the foam. The compression strength of the foam first increased and then decreased with increasing amounts of PEG. When 2 wt% PEGs were added, the compression strength of foams was the highest. The addition of PEG significantly influenced the microstructure of phenol–urea–formaldehyde foams, in which the cell diameter decreased and wall thickness increased with increasing amount and molecular weight of PEG. The addition of PEG also slightly decreased the thermal stability of phenol–urea–formaldehyde foams, and increased the heat release rate, total heat release, and total smoke release of the foams.     

Properties of polyvinyl alcohol cement pastes

Properties of cement pastes containing varying amounts of each of polyvinyl alcohol (PVAL), mixtures of polyvinyl alcohol and phenol formaldehyde (PF) and mixtures of poly vinyl alcohol and borax were studied in this paper. Though the strength parameters of the PVAL-cement pastes are comparable to virgin cement paste their resistance to acid is far superior. Soxhlet extraction with water, done to determine leachability of the polymer from the polymer cement paste, revealed that the percentage of polyvinyl alcohol leached out was less when borax or PF resin was added to the PVAL cement paste. The compressive strength of the poly vinyl alcohol–phenol formaldehyde cement paste was found to be inferior to the other two cases but the retention of compressive strength after immersing in each of acid, base and kerosene was much better. In general, polyvinyl alcohol when added to cement pastes improves the chemical resistance properties in terms of retention of compressive strength after exposure to chemicals.     

A study on crosslinking of phenolic fibers

Phenolic fibers (PFs) were prepared by the crosslinking of heat-meltable spun filaments derived from melt-spinning of a novolac resin with well-controlled molecular weight of 2000 g mol⁻¹, in a combined solution of formaldehyde and hydrochloric acid. The reaction of the heat-meltable spun filaments with the solution of formaldehyde and hydrochloric acid was investigated. IR spectrometer, scanning electron microscopy (SEM), and electrical tensile strength apparatus were employed to characterize the change of functional groups, the distribution of crosslinkage in the interior and surface, and the tensile strength of PFs, respectively. The influence of different parameters during the curing reaction, such as formaldehyde and hydrochloric acid concentration, the effect of heating rate on the properties and structure of the cured fibers were examined. It was found that with a formaldehyde concentration of 18.5%, a hydrochloric acid concentration of 12% and a heating rate of 15.4 °C h⁻¹ homogeneous highly crosslinked phenolic fibers with the maximum tensile strength of 260 MPa were obtained.     

硅灰石填充保鲜膜的性能研究

为增加保鲜膜透气和透湿性能,以LLDPE/LDPE(质量比75∶25)为基材,以硅灰石为填料,制备了不同处理方式和不同添加量的硅灰石保鲜膜。结果表明:随着硅灰石添加量的增加,薄膜的拉伸强度和断裂伸长率逐渐降低,未经处理的硅灰石填充膜的透气和透湿量明显提高,经偶联剂和酸处理的硅灰石能很好地提高与树脂的相容性,薄膜的拉伸强度和断裂伸长率都高于未处理填充膜,且透气系数和透湿系数与空白膜相比也有明显改善。     

Mechanical properties of coated paper: Influence of coating properties and pigment Blends

The effect of percentage solids content, coating film thickness and plastic pigment on mechanical properties of coated paper was studied. The results showed that the tensile strength, TEA, stretch and tensile stiffness were improved as the percentage solids content and the coating film thickness were increased. Bending stiffness slightly increased when solids content was increased and showed higher values on increasing the coating film thickness. The addition of plastic pigment to both clay based and GCC based coating mixtures improved the mechanical properties considered in this study. Although tensile strength and tensile stiffness increased with the addition of plastic pigment of smaller particle size, stretch and TEA showed a reverse trend.     

胡萝卜可食性包装膜的制备及性能

目的 研究胡萝卜可食性食品包装膜,以替代塑料包装材料用于食品包装.方法 以胡萝卜为原材料,添加羧甲基纤维素(CMC)、海藻酸钠、甘油制备可食性膜,研究不同添加量对膜的抗拉强度、热封强度、断裂伸长率以及阻隔性能的影响,以抗拉强度为主要指标,通过正交试验进行工艺优化,并进行验证试验,对力学性能和其他性能进行测定.结果 每100 mL蒸馏水中最佳添加量,胡萝卜浆20 g,羧甲基纤维素2.5 g,海藻酸钠1.6 g,甘油1.5 mL,获得的可食性膜抗拉强度为5.71 MPa,热封强度(15 mm)为3.84 N,断裂伸长率为119.98％,透湿量为439.59 g/(m2·d),透氧量为4.96 cm3/(m2·d·kPa),溶解时间为35 s,膜平均厚度为0.183 mm.结论 根据实验结果,可以获得浅橙色、半透明、质地柔软均匀、平滑无气泡、具有一定强度和韧性、力学性能良好的可食性食品包装膜.     

可食性干酪包装膜的制备及性能研究

目的研究酪蛋白酸钠、壳聚糖、甘油添加量对可食膜性能的影响。方法以酪蛋白酸钠和壳聚糖为原料,甘油作为增塑剂,制备可食性干酪包装膜,以膜的水溶性及力学性能为指标,通过单因素及正交试验,确定各成膜成分的最佳配比。结果当用质量分数为5%的酪蛋白酸钠水溶液、质量分数为2%的壳聚糖冰乙酸溶液和质量分数为2%的甘油混合液进行成膜,所得可食膜的综合性能较优,其水溶性为35.8%,断裂伸长率为75.4%,拉伸强度为10.58 MPa,弹性模量为13.47 MPa。结论随着酪蛋白酸钠含量的增加,膜的水溶性变化不大,膜的断裂伸长率先增大后减小,拉伸强度和弹性模量均随之增大;随着壳聚糖含量的增加,膜的水溶性逐渐下降,膜的断裂伸长率、拉伸强度、弹性模量均随之增大;随着甘油含量的增加,膜的水溶性逐渐减小,膜的断裂伸长率逐渐增大,拉伸强度和弹性模量逐渐减小。     

Improvement of mechanical properties of AA1070 aluminium by the addition of borax under different holding conditions

In this study, mechanical properties of Al‐B alloys, prepared by the addition of different amounts of borax to 99.70% pure commercial aluminum, were improved. The main objective is to study the influence of borax addition and holding conditions on the mechanical properties of cast Al‐B alloys. In this process, amount of borax, holding temperature and holding time were realized as affecting parameters. By considering these parameters three specimens were prepared for each condition and they were subjected to mechanical tests such as tensile, impact and hardness tests. As a result of tests, tensile strength of the alloy with the incorporation of borax was found 33% increase in comparison to pure aluminum while 21% increase in impact energy and 54% in hardness value. A substantial quantity of aluminum‐boride flakes were observed in the microstructural investigation of the samples. Microscopic observations of alloyed samples reveal homogeneous distribution of aluminum boride particles and fewer porosity levels.     

细菌纤维素-ZnO/水性聚氨酯复合薄膜的制备与性能

以细菌纤维素(BC)为模板,以ZnSO₄、NaOH和尿素为原料,通过水热法制备了具有新型刷状结构的细菌纤维素-ZnO(BC-ZnO)复合颗粒,尺寸约为3~5 μm,其中BC含量约为19wt%,并对其可能的形成机制进行阐述。将不同含量的BC-ZnO复合颗粒通过原位聚合法引入到水性聚氨酯(WPU)中得到细菌纤维素-ZnO/水性聚氨酯(BC-ZnO/WPU)复合薄膜,对复合膜的结构与性能进行了表征。结果表明:复合颗粒在WPU中分散良好;复合膜的拉伸强度在BC-ZnO含量为1.0wt%时达到最高,相较于纯WPU提高了84.6%;吸水率从16.5%降到4.9%;BC-ZnO的引入提高了复合膜的初始热稳定性;复合膜具有良好的抗菌性,当BC-ZnO含量为1.3wt%时,对金黄色葡萄球菌的抗菌率超过99%,对大肠杆菌的抗菌率超过85%。      

Biodegradation of porous versus non-porous poly(L-lactic acid) films

The influence of porosity on the degradation rate of poly(L-lactic acid) (PLLA) films was investigated in vitro and in vivo. Non-porous, porous and combi (porous with a non-porous layer) PLLA films were used. Changes in Mw, Mn, polydispersity (Mw/Mn) ratio, melting temperature (T _m), heat of fusion, tensile strength, E-modulus, mass and the remaining surface area of cross-sections of the PLLA films were measured. In general, during the degradation process, the porous film has the highest Mw, Mn, Mw/Mn ratio and T _m, while the non-porous film has the lowest. In contrast, the highest heat of fusion values were observed for the non-porous film, indicating the presence of relatively smaller molecules forming crystalline domains more easily. The tensile strength and E-modulus of the non-porous film decrease faster than those of the porous and the combi film. None of the three types of films showed massive mass loss in vitro nor a significant decrease in remaining polymer surface area in light microscopical sections in vitro and in vivo. Heavy surface erosion of the non-porous layer of the combi film was observed after 180 days, turning the combi film into a porous film. This is also indicated by the changes in tensile strength, Mw, Mw/Mn, T _m and heat of fusion as a function of time. It is concluded that non-porous PLLA degrades faster than porous PLLA. Thus, in our model, porosity is an important determinant of the degradation rate of PLLA films.