丰满少妇被猛烈进入无码,国产精品亚洲欧美在线播放操,无遮挡又黄又刺激又爽的视频,久久久久亚洲AV成人

Welcome to Shenzhen Zhongyuan Plastic Co., Ltd!

News



Tel:(0755)27151698
Fax:(0755)27150611
Mailbox:szzyzcl@163.com / szzy@szzy99.com
Add:Building A1 and A2, No.1 Industrial Zone, yuliu property company, Gongming town, Bao'an District, Shenzhen
Industry information

當(dāng)前位置:

首頁 News Industry information

Causes and effects of internal stress in plastic shell

Release time:2023-05-16

Plastic internal stress refers to a kind of internal stress produced by the plastic shell during the melting process due to the orientation of macromolecular chains, cooling shrinkage and other factors.


The essence of internal stress is the unbalanced conformation of macromolecular chain formed in the melting process. After cooling and curing, this unbalanced conformation cannot immediately return to the equilibrium conformation suitable for environmental conditions. The essence of this unbalanced conformation is a reversible high elastic deformation, and the frozen high elastic deformation is usually stored in plastic shell products in the form of potential energy. Under appropriate conditions, This forced unstable conformation will be transformed into a comfortable stable conformation, and the potential energy will be converted into kinetic energy and released.


When the force and entanglement force between macromolecular chains cannot bear this kinetic energy, the internal stress balance will be destroyed, and the plastic shell will produce stress cracking and warping deformation.


Plastic shellCauses of internal stress

1. Orientation internal stress

The orientation internal stress is the internal stress produced by the arrangement of macromolecular chains along the flow direction and the freezing of orientation conformation in the process of plastic melt flow filling and pressure maintaining feeding.

The detailed process of orientation stress is as follows: the melt near the channel wall cools fast, causing the viscosity of the outer melt to increase. From one point to another, the flow rate of the melt in the core layer of the cavity is much higher than that of the surface layer, causing shear stress between the inner layers of the melt and the orientation along the flow direction.

The thawing of the oriented macromolecular chain in the plastic shell also symbolizes the existence of unreleased reversible high elastic deformation, so the orientation stress is the internal force of the macromolecular chain from the oriented conformation force to the non oriented conformation. The orientation stress in the plastic shell can be reduced or eliminated by heat treatment.

The orientation internal stress distribution of the plastic shell becomes smaller and smaller from the surface to the inner layer of the product, showing a parabolic change.


2. Cooling internal stress

Cooling internal stress is a kind of internal stress caused by uneven shrinkage of plastic shell during cooling and shaping in the melting process. Especially for the thick wall plastic shell, the outer layer of the plastic shell is cooled, solidified and contracted first, and its inner layer may still be hot melt. The core layer will restrict the shrinkage of the surface layer, causing the core layer to be in a state of compressive stress and the surface layer to be in a state of tensile stress.

The distribution of internal stress in the cooling of plastic shell is getting larger and larger from the surface layer to the inner layer of plastic shell, which also changes in a parabola.

In addition, the plastic shell with metal inserts is easy to form uneven internal stress due to the large difference between the thermal expansion coefficients of metal and plastic.

In addition to the above two important internal stresses, there are also the following internal stresses: for crystalline plastic shell, when the crystalline structure and crystallinity of various parts inside the plastic shell are different, internal stress will be generated. In addition, there are configuration internal stress and demoulding internal stress, but the proportion of internal stress is very small.

圖片6-2.png


Factors affecting the internal stress of plastic shell

1. Rigidity of molecular chain

The higher the rigidity of the molecular chain, the higher the viscosity of the melt, and the worse the fluidity of the polymer molecular chain. Therefore, for the reversible high elastic deformation, the recovery is poor, and it is easy to produce residual internal stress. For example, some polymers with benzene rings on their molecular chains, such as PC, PPO, PPS, etc., have higher internal stress in their corresponding plastic shells.


2. Polarity of molecular chain

The greater the polarity of the molecular chain, the greater the mutual attraction force between molecules, which makes the mutual movement between molecules more difficult, reduces the degree of restoring reversible elastic deformation, and produces larger residual internal stress. For example, some kinds of plastics with polar groups such as carbonyl, ester and eyebase in the molecular chain will have relatively large internal stress in the corresponding plastic shell.


3. Steric hindrance effect of substituents

The larger the volume of the side group substituents of macromolecules, the greater the residual internal stress caused by hindering the free movement of macromolecular chains. For example, the volume of phenyl group of polystyrene substituent is large, so the internal stress of polystyrene plastic shell is large.

Copyright: Shenzhen Zhongyuan Plastic Co., Ltd. | mold processing customized manufacturer. If you want to know the processing price of the factory, how much is it, and which is good, please contact us Yue ICP Bei No. 17060480
99在线观看精品视频免费-国产极品一区二区三区四区| 久久影视av一区二区-人妻激情乱偷一区二区三区| 在线视频成人一区二区-亚洲另类中文字幕在线| 欧美视频在线观看国产专区-亚洲91精品在线观看| 美女把腿张开给帅哥桶-无码无套少妇18p在线直播| 中文字幕日韩精品不卡一区二区-成人av在线观看一区二区| 97香蕉久久国产在线观看-麻豆黄色广告免费看片| 国产一区二区无套内射-国内精品久久久久久久齐pp| 国产精品久久久精品一区-99久久免费精品国产男女性高好| mm在线精品视频在线观看-欧美国产日韩在线一区二区三区| 欧美日韩国产亚洲免费-肉体粗喘娇吟国产91| 中文不卡一区二区三区-老司机在线老司机在线一区| 中文不卡一区二区三区-老司机在线老司机在线一区| av噜噜国产在线观看-欧美视频亚洲视频一区二区三区| 亚洲国产精品一区二区av-日本一级黄色一区二区| 国模自慰一区二区三区-日韩一级黄色片天天看| 少妇人妻无码久久久久久-综合图片亚洲网友自拍| 免费av一区在线观看-国产精品视频高潮流白浆视频免费| 日韩毛片在线免费人视频-超碰中文字幕av在线| 看肥婆女人黄色儿逼视频-秋霞电影一区二区三区四区| 99在线观看精品视频免费-国产极品一区二区三区四区| 久久影视av一区二区-人妻激情乱偷一区二区三区| 精品少妇一区二区18-一区二区三区日韩在线播放| 久久网址一区二区精品视频-日产国产欧美视频一区精品| 亚洲综合av一区二区三区-高潮又爽又黄无遮挡激情视频| 亚洲国产精品日韩欧美-国产又粗又硬又大爽黄| 欧美字幕一区二区三区-好吊妞欧美一区二区在线观看| 日本少妇激情一区二区-亚洲自偷自拍熟女另类蜜臀| 7m视频7m精品视频网站-亚洲综合香蕉视频在线| 久久免费观看归女高潮特黄-黄色av一本二本在线观看| 青木玲高清中文字幕在线看-视频在线免费观看你懂的| 丝袜美腿人妻连续中出-在线观看日韩三级视频| 亚洲愉拍自拍欧美精品app-亚洲一区不卡在线视频| 欧美mv日韩mv视频-熟妇人妻ⅴa精品中文| 亚洲av日韩五月天久热精品-国产日韩欧美一区二区三区群战| 亚洲区欧美区在线视频-亚洲碰碰人人AV熟女天堂| 中文字幕精品一区二区日本99-青青国产成人久久91网| 午夜福利卫生纸福利院-一区二区三区久久亚洲| 天天干天天日天天射天天舔-精品香蕉视频官网在线观看| 久久蜜桃精品一区二区-麻豆视频啊啊啊好舒服| 国产精品美女在线网址-久草免费福利在线观看视频|