玉米淀粉材料是生物降解塑料聚乳酸（PLA）的一種，聚乳酸是以乳酸為主要原料聚合得到的聚合物，主要以玉米、木薯等為原料。聚乳酸的生產(chǎn)過程，而且產(chǎn)品可以生物降解，實(shí)現(xiàn)在自然界中的循環(huán)，因此是理想的綠色高分子材料。

Corn starch material is a kind of biodegradable plastic polylactic acid (PLA). PLA is a polymer polymerized with lactic acid as the main raw material, mainly corn, cassava, etc. Polylactic acid is an ideal green polymer material because of its production process and its biodegradation to realize its circulation in nature.

聚乳酸（PLA）是一種新型的生物降解材料，使用可再的植物資源（如玉米）所提出的淀粉原料制成。淀粉原料經(jīng)由糖化得到葡萄糖，再由葡萄糖及一定的菌種制成純度高的乳酸，再通過化學(xué)合成方法合成一定分子量的聚乳酸。其具有良好的生物可降解性，使用后能被自然界中微生物完全降解，生成二氧化碳和水，不污染環(huán)境，這對(duì)保護(hù)環(huán)境非常有利。

Polylactic acid (PLA) is a new type of biodegradable material, which is made of starch from renewable plant resources (such as corn). Glucose is obtained from starch raw material through saccharification, then lactic acid with high purity is made from glucose and certain bacteria, and polylactic acid with certain molecular weight is synthesized through chemical synthesis. It has good biodegradability. After use, it can be completely degraded by microorganisms in nature to generate carbon dioxide and water. It does not pollute the environment, which is very beneficial to environmental protection.

聚乳酸適用于吸塑、注塑等各種加工方法，加工方便，應(yīng)用十分廣泛?？捎糜诩庸墓I(yè)到民用的各種食品容器、包裝食品、快餐飯盒、無紡布、工業(yè)及民用布。進(jìn)而加工成農(nóng)用織物、抹布、衛(wèi)生用品、帳篷布、地墊面等等，市場(chǎng)前景十分看好?？梢娖錂C(jī)械性能及物理性能良好。

Polylactic acid is suitable for various processing methods such as blister and injection molding. It is easy to process and widely used. It can be used to process all kinds of food containers, packaged food, fast food lunch boxes, non-woven fabrics, industrial and civil fabrics from industry to civil use. And then processed into agricultural fabrics, rags, sanitary products, tent cloth, floor mats and so on. The market prospect is very promising. It can be seen that its mechanical and physical properties are good.

相容性與可降解性良好。聚乳酸在醫(yī)藥領(lǐng)域應(yīng)用也非常廣泛，如可生產(chǎn)一次性輸液用具、免拆型縫合線等，低分子聚乳酸作藥緩釋包裝劑等。

Good compatibility and degradability. Polylactic acid is also widely used in the pharmaceutical field, such as the production of disposable infusion equipment, non detachable suture, low molecular polylactic acid as drug release packaging agent, etc.

當(dāng)焚化聚乳酸（PLA）時(shí)，其燃燒熱值與焚化紙類相同，是焚化傳統(tǒng)塑料（如聚乙烯）的一半，而且焚化聚乳酸不會(huì)釋放出氮化物、硫化物等有毒氣體。人體也含有以單體形態(tài)存在的乳酸。

When polylactic acid (PLA) is incinerated, its combustion calorific value is the same as that of incinerated paper, half of that of incinerated traditional plastics (such as polyethylene), and the incinerated PLA will not release toxic gases such as nitrides and sulfides. The human body also contains lactic acid in monomer form.

玉米淀粉顆粒之聚乳酸的優(yōu)點(diǎn)主要有：一是原材料易得可再生，適合大規(guī)模集約化生產(chǎn)；二是透氣性能、透明度光澤和硬度、拉伸和彎曲均可與傳統(tǒng)的塑料樹脂相媲美；三是更好的生物相容性。其單體原料L-乳酸是人體內(nèi)源性活物質(zhì)，因此聚乳酸制品對(duì)人體不排斥，并可被人體吸收，能制成醫(yī)用組織骨架材料和醫(yī)藥載體用于人體內(nèi)，并獲得美國FDA認(rèn)證；四是完全可降解性。埋入土壤中6～12個(gè)月即可降解成二氧化碳和水。

The advantages of PLA with corn starch granules are as follows: first, raw materials are easily available and renewable, which is suitable for large-scale intensive production; Second, the air permeability, transparency, gloss, hardness, stretching and bending can be comparable with the traditional plastic resin; Third, better biocompatibility. Its monomer L-lactic acid is an endogenous living substance in human body. Therefore, polylactic acid products are not exclusive to human body and can be absorbed by human body. They can be made into medical tissue skeleton materials and medical carriers for use in human body, and have been certified by FDA; Fourth, complete degradability. It can be degraded into carbon dioxide and water after being buried in soil for 6 ~ 12 months.

聚乳酸的制備方法

Preparation of polylactic acid

1）直接縮聚法

1) Direct polycondensation

縮聚法就是把乳酸單體進(jìn)行直接縮合，也稱一步聚合法。在脫水劑的存在下，乳酸分子中的羥基和羧基受熱脫水，直接縮聚合成低聚物。加入催化劑，繼續(xù)升溫，低相對(duì)分子質(zhì)量的聚乳酸聚合成更高相對(duì)分子量的聚乳酸。

Polycondensation is the direct condensation of lactic acid monomer, also known as one-step polymerization. In the presence of dehydrating agent, hydroxyl and carboxyl groups in lactic acid molecules are dehydrated by heating, and oligomers are synthesized by direct polycondensation. Add catalyst and continue to heat up, and poly (lactic acid) with low relative molecular weight can be polymerized to poly (lactic acid) with higher relative molecular weight.

2）二步法

2) Two step method

使乳酸生成環(huán)狀二聚體丙交酯，再開環(huán)縮聚成聚乳酸。這一技術(shù)較為成熟，美國NatureWorks公司生產(chǎn)聚乳酸工藝的工藝即為該工藝。的海正與中科院共同研制的聚乳酸生產(chǎn)技術(shù)也與此相似，主要過程是原料經(jīng)微生物發(fā)酵制得乳酸后，再經(jīng)過精制、脫水低聚、高溫裂解，聚合成聚乳酸。

Lactic acid is made into a cyclic dimer lactide, and then ring opening polycondensation is carried out to form polylactic acid. This technology is relatively mature, which is the process of producing polylactic acid by NatureWorks in the United States. The polylactic acid production technology jointly developed by Haizheng and Chinese Academy of Sciences is similar to this. The main process is that the raw materials are fermented by microorganisms to produce lactic acid, then refined, dehydrated and oligomerized, high-temperature pyrolysis, and finally polymerized into polylactic acid.

3）反應(yīng)擠出制備高分子量聚乳酸

3) Preparation of high molecular weight polylactic acid by reactive extrusion

用間歇式攪拌反應(yīng)器和雙螺桿擠出機(jī)組合，進(jìn)行連續(xù)的熔融聚合實(shí)驗(yàn)，可獲得由乳酸通過連續(xù)熔融縮聚制得的分子量達(dá)150000的聚乳酸。利用雙螺桿擠出機(jī)將低摩爾質(zhì)量的乳酸預(yù)聚物在擠出機(jī)上進(jìn)一步縮聚，制備出較高摩爾質(zhì)量的聚乳酸。在反應(yīng)溫度為150℃、催化劑用量為0.5%、螺桿轉(zhuǎn)速為75r/min時(shí)可通過雙螺桿反應(yīng)擠出縮聚法快速有效地提高聚乳酸的摩爾質(zhì)量，而且反應(yīng)擠出產(chǎn)物分散系數(shù)減小，均勻性變好。通過DSC曲線的比較發(fā)現(xiàn)，通過反應(yīng)擠出縮聚法制得的聚乳酸的結(jié)晶度有所降低，這對(duì)改善聚乳酸材料在使用過程中表現(xiàn)出較大的脆性是有益的。

The continuous melt polymerization experiment was carried out in a batch stirred reactor and a twin-screw extruder. The polylactic acid with molecular weight up to 150000 was prepared from lactic acid by continuous melt polycondensation. The low molar mass of lactic acid prepolymer was further polycondensated on the twin-screw extruder to prepare high molar mass of polylactic acid. When the reaction temperature is 150 ℃, the amount of catalyst is 0.5% and the screw speed is 75r/min, the molar mass of polylactic acid can be rapidly and effectively increased by twin-screw reactive extrusion polycondensation, and the dispersion coefficient of reactive extrusion products is reduced and the uniformity is improved. Through the comparison of DSC curves, it was found that the crystallinity of polylactic acid prepared by reactive extrusion polycondensation decreased, which was beneficial to improve the brittleness of polylactic acid materials in the process of use.

玉米淀粉顆粒材料聚乳酸的使用相關(guān)內(nèi)容便是如此了，您可以關(guān)注我們的網(wǎng)站www.qylxschool.cn咨詢更為詳細(xì)的信息。

This is the case with the use of corn starch granule material polylactic acid. You can follow our website www.qiluxinke Com for more detailed information.