ME 8883 Paper Physical Property MeasurementsPaper Property MeasurementsPaper Physical Property MeasurementsGradingTappi test methodsAn example of the effect of moistureIR methods for moistureME 8883 # 1: intro, sampling, moisture, basis weight1ME 8883 Paper Physical Property MeasurementsInstructor:Dr. Roman E. Popil (Ph.D. 1984, Plasma Physics, UBC) office: 333, ph 404 894 9722, e-mail: [email protected] Research ScientistInstitute of Paper Science and TechnologyTuesdays and Thursdays, 1:35 to 2:55 pmME 8883 # 1: intro, sampling, moisture, basis weight2Paper Property Measurements• Principles of measurements, significance to paper quality issues• Hands-on demonstrations in the lab, pragmatics of instrument maintenance and calibration, emphasis will be on standard Tappi methods, some discussion of specialized methods• How to use physical property measurements to solve paper quality and manufacturing problemsME 8883 # 1: intro, sampling, moisture, basis weight3Paper is a complex orthotropic, anisototropic and hygroscopic mess– (no surprise) Recent laser confocal shot of a softwood lab handsheet 40X mag. A conglomeration of fibers, each fiber is different than the next What does that mean to you ? – Paper is lumpy, bumpy, fuzzy stuff !!•Be awarethat there is a lot of variability in all properties betweensamples and within a sample – all measurements must consist of at 6 or more repeats • there a 3 directions to machine made paper: MD (x, 1, 11) CD (y, 2, 22) ZD (z, 3, 33), mechanical properties in these three directions are all different• paper retains moisture and “remembers” its moisture history –mechanical properties are dependent on paper moisture in a non-linear fashion !ME 8883 # 1: intro, sampling, moisture, basis weight4Paper Physical Property MeasurementsTopics:1. basis weight, moisture density2. Caliper, hard and soft3. Tensile strength, stretch to break, TEA, Instron and L&W methods4. tear, burst, ZDT, fold, zero span tensile5. Ultrasonic stiffness, stiffness orientation plot6. Hygroexpansivity7. Roughness: air leak and profilometry, 3D shadow Moire, gloss8. Formation: optical transmission, electrography9. Opacity, brightness 10. Color11. Bending stiffness, 2 point L&W, Taber and L&W 4 point12. Linerboard: Ring crush and STFI13. Corrugated Board: ECT, BCT, creep, Concora crush14. Water absorption: water drop, contact angle , Cobb, WVTTR, size testerME 8883 # 1: intro, sampling, moisture, basis weight5Grading• 3 lab sessions are in the plan – using the techniques demonstrated and learned, produce a cohesive set of measurements on a sample set to produce a complete description of paper properties and their interrelationships• Final closed book exam – check of retention of recollection of the basicsME 8883 # 1: intro, sampling, moisture, basis weight6PAPER STUCTURE -OVERSIMPLIFIEDFibers: former wood cells, typically 1 – 3 mm log 50 microns wide ZDCDMDPaper consists of 50 to 30% air and a network of bonded fibers aligned predominantly along the MD – machine directionME 8883 # 1: intro, sampling, moisture, basis weight7Moisture Hysteresis Curve of PaperWink from IPST produced a curve of the moisture content of paper versus relative humidity quoted in textbooks, “going up the curve is not the same as going down”Paper once wet, is never the same again.If you put paper in a high humidity environment e.g. 90%RH it will absorb moisture to have a moisture content (i.e. wet – dry weight/wet weight) of 11% , take it back down to 50% it will have a moisture content of maybe 9%But, if you take paper to 20% RH, then up to 50% RH, it will likely have a moisture content of 7% RH repeatably- Do you know where your sample has been ? Your sample knows ! Tappi method 404 – condition paper samples at 20% RH for 24 hrs, then condition samples for 50% RH for 24 hours prior to any measurementsMoisture Control in 351 and 352• Adjoining 351 is room 352 – this is the dry room, maintained at 20% RH and 73 deg C. note the circular chart on the wall new samples to be tested stay here on the racks for 24 hours make sure air can get to the surfaces of your samples by hanging them up on the racks• after 24 hours in the dry room, hang your samples on the racks to condition in 351 lab maintained at 50%RH 73 deg C,-Make sure you have you samples labeled with name, phone number and date, the racks are for conditioning samples, not storage, samples left on the racks are periodically discarded withoutnotice !- After your samples have finished the conditioning sequence, store them in sealedplastic bags, the conditions in lab 351 are subject to fluctuation and upsets by outside weather !! - If your samples are ever subjected to humidity above 5% RH, they must re- conditioned: 24 hours at 20% RH followed by 24 hours at 50 %RHME 8883 # 1: intro, sampling, moisture, basis weight8ME 8883 # 1: intro, sampling, moisture, basis weight9Tappi test methods• most of the testing methods we will discuss are industry standardized methods decided and reviewed by Tappi committees that meet at regular Tappi conferences• this ensures universal quality standards that characterize paper as a commercial product• each method is designated as T- ### - letter suffix, 400 – 500 is Paper ands Paperboard testing, 800’s are Containerboard tests, - om designates an official method, - pm provisional method•Let’s look at the first one:ME 8883 # 1: intro, sampling, moisture, basis weight10ME 8883 # 1: intro, sampling, moisture, basis weight11Paper is highly variable, non-uniform, how many samples and measurements do you need to take to characterize a paper property ? Sample cut along the MDA sample is associated with a certain grade, process parameters, each sample will have several specimens or replicates MDPaper from mills usually supplied in roll formME 8883 # 1: intro, sampling, moisture, basis weight12Front or Tending SideBack or Drive SideMDPaper from a paper machine has a variation in the MD and the CD, CD variation arises from drying profiles, headbox edge flows, MD are high frequency variations, focs, wire marks, etc.ME 8883 # 1: intro, sampling, moisture, basis weight13Most measurements are made with several repeats (6 or more) on several specimens from a sample.ME 8883 # 1: intro, sampling, moisture, basis weight14ME 8883 # 1: intro, sampling, moisture, basis weight15Samples for mechanical property testing have to placed in a