聚丙烯酸表面接枝改性聚丙烯抗氧化膜的制备与性能

Preparation and Characterization of Anti-Oxidation Packaging Films Based on Poly(acrylic acid)Grafting Polypropylene Surface

为解决微量过渡金属离子能够催化食品氧化的问题,利用紫外光表面接枝技术将丙烯酸(AA)接枝到聚丙烯(PP)膜表面,制备具备金属离子螯合能力的PP-g-PAA抗氧化膜。采用红外光谱、扫描电镜和金相显微镜对膜结构和形貌进行了表征。结果表明,获得了致密均匀的聚丙烯酸(PAA)接枝层;通过控制接枝时间获得了不同的羧基密度。采用TBO染色法和原子吸收光谱考察了膜表面羧基密度、Cu^(2+)螯合量及两者的比例关系。当膜表面羧基密度小于4.24μmol/cm^2时,羧基量与Cu^(2+)螯合量之比为4,说明两者能够形成稳定的五元环螯合结构,起到抑制金属离子催化氧化的作用;考察紫外光接枝对膜力学性能和阻隔性能的影响,接枝时间达到20 min时,膜的断裂伸长率急剧下降,氧气阻隔性能显著提高。

In order to solve the problem that trace transition metal ions can catalyze the oxidation of food,acrylic acid(AA)was grafted onto the surface of PP film by ultraviolet surface grafting technology to prepare PP-g-PAA film.The PP-g-PAA film could restrain oxidation with metal ion chelating ability.The structure and morphology of the film were characterized by FT-IR,SEM and metallographic microscope.The results show that a dense and uniform poly(acrylic acid)(PAA)grafting layer on the PP-g-PAA film is obtained.Different carboxyl density can be obtained by controlling the grafting time.The carboxyl group density,Cu2+chelating amount and the ratio of the two were studied by dyeing method and atomic absorption spectrometry.When the carboxyl group density of PP-g-PAA film is less than 4.24μmol/cm2,the ratio of the carboxyl group to the Cu2+chelating amount is about 4,indicating that they can form a stable five-membered ring chelating structure to inhibit the catalytic oxidation of metal ion.The effect of UV grafting reaction on the mechanical properties and barrier properties of the film was investigated,when the grafting time reaches 20 min,the elongation at break of the film is drastically reduced,but the oxygen barrier performance is significantly improved.